Gen Thorac Cardiovasc Surg (2014) 62:273–281 DOI 10.1007/s11748-014-0388-8
CURRENT TOPICS REVIEW ARTICLE
Bad Aorta Kazuyoshi Tajima
Received: 29 July 2013 / Published online: 18 March 2014 Ó The Japanese Association for Thoracic Surgery 2014
Abstract As its outcomes improve, cardiac surgery has been performed on more and more cases which were previously considered to be difficult to deal with. However, there are still a number of problems to be solved regarding surgery on patients with severe sclerotic lesions in the ascending aorta, which we collectively call ‘‘bad aorta’’. Concerning a preoperative assessment of the ascending aorta, our report revealed no relationship between the severity of calcification detected with a preoperative nonenhanced CT and the aortic lesion found during the surgery. Meanwhile, an intraoperative epiaortic ultrasound enables us to make high-quality evaluations of the aorta without imposing much burden on the patient. This modality may be essential for cardiac surgery. As for surgical management for bad aorta, quite a few methods have been reported to this point, but the overall operative mortality rate and cerebrovascular accident rate are relatively high, at a little \10 %, respectively. With the recent crossclamping method under short-term total circulatory arrest (TCA), however, the results are much better; these rates total around 5 %. Further improvement is expected in the outcome of cardiac surgery on bad aorta cases by establishing a modality to evaluate sclerotic lesions in the ascending aorta with epiaortic ultrasound and by selecting a proper procedure for each case. Keywords Porcelain aorta Shaggy aorta Circulatory arrest Aorta clamping Epiaortic ultrasound
This review was submitted at the invitation of the editorial committee. K. Tajima (&) Department of Cardiovascular Surgery, Nagoya Daini Red Cross Hospital, 2-9 Myoken-cho, Showa-ku, Nagoya 466-8650, Japan e-mail: [email protected]
Introduction Severe sclerosis in the ascending aorta has been increasingly encountered in cardiac surgery with the aging and the increase in hemodialysis cases among cardiac surgical patients in recent years. Since sclerotic lesions developed in the area from the ascending aorta to the aortic arch expectedly raise the risk of cerebral embolization and embolization to visceral vessels [1–4], special consideration should be given when establishing a cardiopulmonary bypass (CPB), achieving a cardiac arrest, and incising the aorta. In this article, some strategies to address such cases reported to date are reviewed, and the approach we are taking at our institution is shown. Cases discussed here are those which require the use of CPB and aortic clamping. Coronary artery bypass grafting (CABG) cases are not included because the risk stated above can be avoided using off-pump CABG which does not require CPB. Isolated mitral valve surgery is not included here either because it can be performed without an aortic incision and there is an alternative way of surgery with the heart beating. What is ‘‘bad aorta’’? Aortic sclerosis occurs as severe aortic wall calcification (Fig. 1), liquid-rich atheroma in the aorta (Fig. 2) or both. Such severe aortic sclerosis has been called by different names, e.g. ‘‘diseased aorta,’’ ‘‘shaggy aorta,’’ ‘‘porcelain aorta,’’ and ‘‘eggshell aorta’’ [5–8], and each of them has a slightly different meaning. However, since which expression is used does not make any difference in difficulty of surgery, we have collectively named any aorta with sclerotic lesions in the ascending aorta for which a standard surgical approach should be avoided ‘‘bad aorta’’ [9].
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Fig. 1 Porcelain aorta: unenhanced 3D CT shows severe calcification of the entire aorta
Fig. 2 Shaggy aorta: preoperative epiaortic ultrasound shows intimal thickening and protruding plaque inside the aorta
Assessment of the aorta A commonly used diagnostic modality to evaluate ‘‘bad aorta’’ is a preoperative unenhanced CT scanning, which
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enables us to evaluate the sclerotic type in the aorta. However, an unenhanced CT can only detect the degree of aortic wall calcification, not the presence of atheroma in the aorta. In order to detect protruding atherosclerotic plaque, contrast-enhanced CT may be useful. An enhanced dual-helical CT with thin sections has been reported to be effective, detecting 95 % of what transesophageal echocardiography (TEE) can find [10]. However, it may be unnecessarily generalized, therefore inappropriate, to use enhanced dual-helical CT as a screening for standard cardiac surgery which only focuses on the aortic root and proximal ascending aorta. TEE is said to be a relatively reliable modality which can provide accurate measurement of plaque thickness and detect mobile thrombi as well [11, 12]. The problem is that it may impose too much burden on heart disease patients if it is applied when they are awake [13]. During surgery, when patients are under anesthesia, on the other hand, epiaortic ultrasound excels TEE in providing images of the ascending aorta. The quality of images is very high and the detected location of plaques and/or calcium deposits is precise with an intraoperative epiaortic ultrasound because its transducer is placed directly on the aorta [14]. Aortic plaque detected by this technique has been reported to predict early and late complications of heart surgery, including stroke and renal insufficiency [15, 16]. After all of these considerations, an intraoperative epiaortic ultrasound is now conducted on all the cardiac surgical patients, regardless of the findings of a preoperative CT, at our institution. Now magnetic resonance imaging (MRI) is also used for the evaluation of aortic plaque in some cases. However, it is said that MR angiography tends to underestimate plaque thickness in the aortic arch because of difficulties in defining the aortic wall [17]. The advantage of MRI, according to some reports, is that it can reveal contrasts between different tissue types, identifying morphological components of the atherosclerotic plaque, such as calcification, fibrocellular tissue, lipid, and thrombus [18, 19]. Since plaque stability depends on the size of the lipid core, the thickness of the fibrous cap and inflammation within the cap, MRI can be helpful in evaluating these parameters [20]. Relationship between aortic calcification detected with preoperative CT and lesions found during surgery In order to examine whether it is possible to anticipate the presence of aortic atheroma from the aortic calcification detected with a CT, preoperative CT findings and aortic lesions (atherosclerotic plaque and/or protruding calcification) found during surgery were compared in 50 bad aorta cases at our institution. The degree of calcification in the
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Fig. 3 The degree of calcification in the ascending aortic wall detected with a preoperative CT was graded into five groups: grade 0 (no calcification, 2 cases), I (calcification in \25 % of the entire circumference, 23 cases), II (25–50 %, 14 cases), III ([50 %, 7 cases), IV (100 %, 4 cases). This indicates no relationship between the aortic calcification grade and the presence of mobile plaque and/or protruding lesions found during surgery
ascending aortic wall detected with a preoperative CT was graded into five groups, which are grade 0 (no calcification, 2 cases), grade 1 (calcification in \25 % of the entire circumference, 23 cases), grade 2 (25–50 %, 14 cases), grade 3 ([50 %, 7 cases) and grade 4 (100 %, 4 cases), and the number of the cases which actually had treatment of the aorta was counted. The percentage of the cases which needed treatment during surgery was 50 % for grade 0, 30 % for grade 1, 50 % for grade 2, 43 % for grade 3 and 50 % for grade 4, indicating no relationship between the aortic calcification grade detected preoperatively and the presence of mobile plaque and/or protruding lesions found during surgery (Fig. 3). This result shows that unenhanced CT is insufficient for the preoperative risk evaluation of aortic clamping, and accordingly, some argue that enhanced CT should be necessary [21]. However, the use of a contrast medium is not preferable since patients suffering from bad aorta are usually old. Furthermore, according to Bergman et al. [22], epiaortic ultrasound works better than CT scanning, enhanced or unenhanced, in diagnosing atherosclerosis in the ascending aorta. The author agrees with them there and believes that a preoperative enhanced CT is not essential. What should we have in mind? When the surgery requiring a cardiac arrest is performed on patients with bad aorta detected by a preoperative chest CT, the following three issues should be taken into account: first, selection of the cannulation site for a CPB; second, whether it is possible to clamp the ascending aorta safely; and third, whether incision and suture of the
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ascending aorta are possible. To make correct judgments on these issues, intraoperative epiaortic ultrasound is essential, and actually performed in all cases at our institution, regardless of the preoperative CT evaluation of the aorta. Even if a CT image shows mild or even no sclerosis, intraoperative epiaortic ultrasound detects mobile plaques inside the wall in some cases (Fig. 4). Moreover, preoperative identification of plaques and/or calcium deposits in the ascending aorta with an enhanced CT or TEE cannot really indicate their precise location, and thus whether to perform aortic cannulation or aortic clamping is often determined with intraoperative epiaortic ultrasound [22]. Use of a handheld probe provides definitive locality of aortic atheroma since the lesion is present immediately beneath the probe. In regard to epiaortic ultrasound, there have been many articles discussing the findings to be watched [3, 23–25]. The French aortic plaque in stroke (FAPS) group, for example, evaluated a large number of patients with different plaque thicknesses and found that in those with a plaque thickness [4 mm the odds ratio for stroke was significantly larger [26]. The odds ratio for a stroke in patients with 1 mm plaques was 1.0 (no increased risk); for 1–3.9 mm plaques it was 3.9; and for plaques [4 mm it was much higher, 13.8. The following findings around the proposed clamping site are the indications which we consider that urge us to take some careful approach in performing aortic cross-clamping. 1. 2. 3.
Intimal thickening of more than 3 mm. Protruding lesion. Severe calcification.
The plaque thickness has been determined based on the figures shown above, allowing some safety margin. When these findings are observed, solutions should be sought for the above-mentioned three issues.
Surgical management for bad aorta First issue If there is even the smallest doubt about finding a suitable cannulation site on the ascending aorta, an alternative site should be looked for on branches such as axillary arteries, subclavian arteries or femoral arteries without any hesitation. Since patients with bad aorta often have severe sclerosis in their femoral arteries as well and there is a danger of atheroemboli caused by retrograde perfusion through an atherosclerotic or aneurysmal descending aorta, it is better to select the right axillary artery as a cannulation site [27, 28]. An 8-mm graft sewn to the axillary artery in an end-to-side fashion ensures a sufficient perfusion flow [29].
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Fig. 4 The aorta seems to be normal in an unenhanced CT (left), but mobile plaque is observed inside the aorta in epiaortic ultrasound (right)
Second issue The following approaches have been reported to deal with the cases where an aortic clamping may cause an embolism (Table 1). Aortic valve surgery under deep hypothermic circulatory arrest (DHCA) This is an aortic valve replacement performed in a short limited time. After achieving deep hypothermia with a CPB, the circulation is arrested, followed by the incision in the ascending aorta without an aortic clamping. According to the reports by Gillinov et al., who have dealt with a large volume of such cases, the operative mortality rate was 12 % and the postoperative stroke rate was 4 %, which were relatively high. The recent report by Chung et al., however, shows excellent outcomes with no intraoperative deaths or cerebrovascular accidents. This may be because the improvement in technique has shortened the duration of the circulatory arrest. The disadvantage of this surgery under DHCA is that given time is limited. For this reason it is only applicable to isolated AVR and it is nearly impossible to perform complex surgery. Aortic endarterectomy under DHCA This is a surgical procedure which involves peeling the entire calcified area in the ascending aorta. The process up to the aortic incision is the same as in the aortic valve surgery under DHCA described above, and after peeling the calcified area, an aortic cross-clamping and standard cardiac surgery follow. Some reports on this procedure were seen until the early 2000s, but there have not been any these days. The reason for this may be the high incidence rate of stroke, which was 18.6 %. The average mortality rate obtained from all those reports, on the other hand, was not really high (3.5 %). This procedure is applicable to complex surgery because a standard procedure can be performed once the aorta is clamped.
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Ascending aorta grafting under DHCA In this procedure, a graft is anastomosed to the distal ascending aorta first, and after this anastomosed graft is clamped, standard surgery is performed. Although this has been the most popular approach, the overall mortality rate is not sufficiently low, being around 10 %. This procedure is applicable to any cardiac surgery. The approach where selective cerebral perfusion is used combined with DHCA has also been reported as a modified method [45, 49]. Surgery under balloon occlusions This procedure is performed under the aortic occlusion which is achieved by placing an occlusion balloon catheter in the ascending aorta. A balloon catheter can be inserted either antegradely or retrogradely, but it is difficult to hold the balloon in proper position. Zingone et al. [46], who have reported the largest number of these cases, mentioned that the mortality rate for isolated valve surgery was extremely high (38.5 %) and that the approach using balloon occlusion was frequently ineffective and had a higher risk of in-hospital death as well as a higher risk of stroke. We have also observed that it is very difficult to position the catheter correctly, and that it should always be made sure that the proximal brachiocephalic artery is not being occluded. This approach has been devised to deal with porcelain aorta, and is rather dangerous for the cases with mobile plaques. Other approaches Apico-aortic valved conduit (AAVC) This procedure was presented by Cooley et al. [50] in 1975. It was first devised to deal with the left ventricular outflow tract obstruction (LVOTO), and the early performances by
Gen Thorac Cardiovasc Surg (2014) 62:273–281 Table 1 Operative management of bad aorta in relevant literature and main outcomes
Method
‘Simple’ AVR under DHCA
277
Author
Year
Aortic tube grafting under DHCA
a
CVA
n
n
%
71
NA
0
0
Coselli [31]
1986
2
NA
NA
0
0
Byrne [32] Silberman [33]
1998 2002
3 8
68 72
58 38
0 0
0 0
Gillinov [34]
2000
24
72
54
3
4
17
Aranki [35]
2005
13
77
44
0
2
15
Chung [36]
2012
11
68
30
0
0
62
3
12
%
4.8
6
9.7
Culliford [37]
1986
13
66
3.5–12
0
1
7.7
Svensson [38]
1996
6
74
NA
0
1
16.7
Stern [39]
1999
43
NA
NA
0
15
34.9
Vogt [40]
1999
22
68
21
1
4.5
1
4.5
Gillinov [34]
2000
16
72
13
3
19
2
12
Aranki [35] Subtotal
2005
13 113
79
9
0 4
3.5
1 21
Wareing [41]
1993
27
NA
29
1
3.7
0
King [42]
1998
17
NA
NA
4
23.5
3
Gillinov [34]
2000
12
72
13
3
25
0
Kouchoukos [43]
2000
83
NA
NA
7
8
3
7.6 18.6 17.6 3.6
Aranki [35]
2005
44
79
27
3
6.8
6
13.5
Girardi [44]
2005
25
75
19
2
8
1
4
Zingone [45]
2010
64
72
34a
272
7
10.9
4
6.3
27
9.9
17
6.3
Gillinov [34]
2000
4
72
5
0
Zingone [46] Kim [47]
2006 2013
52b 1
75 79
0 0
13 0
25
2 0
3.8
13
22.8
2
3.5
57
0
Others Inspect and cross-clamp
Gillinov [34]
2000
6
NA
NA
0
TCA-Clamp
Tajima [48]
2013
96
70
3.6
3
3.2
2
2.1 2
Under antegrade and/or retrograde brain perfusion
b
Operative mortality
1
Subtotal HCA hypothermic circulatory arrest, CVA cerebrovascular accident, NA not available
HCA (min)
1984
Subtotal Balloon occlusion
Age
Jacobowitz [30]
Subtotal Aortic endarterectomy under DHCA
Patients (n)
Including isolated CABG
Cooley [51] himself on 23 cases resulted in three early deaths (13 %). Cooley’s approach has been largely replaced with the Ross or Ross–Konno procedure since the 1990s because late complications caused primarily by conduit tissue valve dysfunction were frequent in children [52]. It has not been recognized as a standard procedure for about 25 years. However, as the number of cardiac surgical cases with severe sclerosis increases, this procedure has been spotlighted again [53], which Cooley himself described as ‘‘revisited’’. The improvement in prosthetic valves and
0
Subtotal
102
3
2.9
2
Total
606
50
8.3
48
7.9
conduit suturing, which contributed to the solution to the long-term problems, such as left ventricular pseudoaneurysm and prosthetic valve dysfunction, also seems to be behind the revaluation of Cooley’s work. Now AAVC often appears in reports on porcelain aorta cases although it was first devised to deal with LVOTO [54, 55]. The advantage of this procedure is that it can be performed without touching the ascending aorta and that it does not require a cardiac arrest. It also can be done without a CPB [56]. Takemura et al. [57] performed AAVC surgery on 7 elderly patients, who were all around 80 years old, between
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278
Fig. 5 Procedures performed in TCA-clamp method
2001 and 2005. No operative deaths were reported, but there was one case of descending aortic dissection, which consequently raised the following issues: the condition of the descending aorta should be closely watched; there is a risk of cerebral embolism caused by retrograde perfusion through the sclerotic descending aorta; and there is a possibility of an incidence of mitral regurgitation coming from a displacement of the mitral valve papillary muscle as a long-term outcome. This procedure is limited to aortic valve stenosis cases and not applicable to complex surgery. Cross-clamping under short-time total circulatory arrest (TCA-Clamp) In 2000, Gillinov et al. reported that there were no operative deaths or strokes in 6 patients for whom the aorta was cross-clamped at a safe spot revealed in the inspection of the aorta during HCA. The TCA-Clamp method is an improved version of Gillinov’s. First, the circulation is arrested temporarily under mild hypothermia (31–33 °C), followed by a close internal inspection of the ascending aorta from the partial transverse incision for AVR. After mobile plaques or protruding lesions which may cause an embolism are quickly cleared by a device such as a cavitron ultrasonic surgical aspirator (CUSA), the circulation is restarted, and then the aorta is clamped expelling the remaining debris and air [9] (Fig. 5). The target temperature for hypothermic state depends on the epiaortic ultrasound findings. When aortic clamping is assumed to be possible without any treatment to prepare a safe clamping site, the temperature with mild hypothermia is low enough. If the time needed for the treatment of the aortic lesions is estimated to be long, moderate hypothermia (25–30 °C) will be adopted. When the brain
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temperature drops as low as 28 °C, the cerebral metabolic rate for oxygen (CMRO2) decreases to a half, which allows us to totally arrest the circulation for about 10 min [58]. The longest time needed for intra-aortic treatment under TCA was 7 min in our cases. We performed this procedure on 96 patients, the average age of whom was 70 years old. The results were satisfactory. The average duration of the circulatory arrest was 3.6 min. There were 3 cases of hospital death (3.2 %) and 2 cases of stroke (2.1 %), but one of them was only transient and the patient fully recovered [48]. This procedure can be applied to not only porcelain aorta but also any case involving bad aorta. Since the cardiac procedure can be performed in a conventional manner once the aorta is safely clamped, it is also applicable to operations other than AVR. The problem with this method is that the positive predictive value is low despite the high sensitivity. Of the 50 cases which were found positive with epiaortic ultrasound, as many as 30 cases had only light intimal lesions and the aorta was safe to crossclamp. In those cases, an inspection was made but the procedure to prepare a clamping site was determined to be unnecessary. Meanwhile, Nishi et al. successfully cross-clamped the artery by placing the clamp parallel to the calcified lesion. Eleven patients who had calcification in \75 % of the entire circumference of the ascending aorta underwent surgery in that manner. None of them had a postoperative neurological complication, according to them [59]. We also cross-clamp the aorta parallel to the calcified lesion in many of the cases for which the preparation of a safe clamping site has been determined to be unnecessary. However, with the TCA-clamp method, this technique is performed much more safely because the aorta is clamped under a direct internal observation and with a clamp simulation. Third issue When there is severe calcification along the incision line, aortotomy and suture of the aorta become difficult to perform. Many reports were published in the past on techniques in suturing calcified vessels. Ascer et al. [60] described the techniques of crushing the arterial wall to fragment the calcification. Others have suggested endarterectomy before suturing because the calcification is confined to the intima and media [61]. Carpenter et al. [62], Hutson et al. [63] and others made holes for suturing using a 23-gauge hypodermic needle as drill bits. According to Kudo et al., debris was not released inside the aorta if an oscillating saw was used in making an incision. They first performed a 1-cm-wide endarterectomy of the calcified intima, and sutured the incision with a bovine pericardial strip as a reinforcement. They reported one successful case where progress was satisfactory with no brain complication [64].
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Our view toward the safe suture is the same as Carpenter et al.’s. At our institution the aorta is sutured after achieving endarterial decalcification only along the suture line using CUSA, which has been successful.
Problem at issue The TCA-clamp method is considered to be an excellent procedure which is technically easy to perform and involves very little risk. However, the positive predictive value obtained from epiaortic ultrasound is so low that in many cases inspections are not followed by a treatment of the aorta. Improving the positive predictive value is one issue to be addressed. Although a combination of some preoperative enhanced CT scans may help us make better judgments, it has the risk of imposing too much burden on patients. This does not make any sense because the TCAclamp itself is a minimally invasive procedure. Accuracy in judgment should be improved with better analysis of intraoperative findings. Strength of the aortic wall after the treatment such as decalcification by CUSA is also an issue to be studied. Of the 41 cases of aortic wall treatment done with the TCAclamp method, no incidence of pseudoaneurysm at the treatment site has been encountered at our institution to this point during the follow-up period, which is 12 years at the longest. However, the follow-up period is still short, and thus it is necessary to continue to watch the progress closely. The recent introduction of transcatheter aortic valve replacement (TAVR) seems to bring quite a few successful outcomes regarding the treatment of porcelain aorta in isolated AVR surgery [65–67]. However, it is assumed to be rather risky when dealing with shaggy aorta. Therefore, it may not be applicable to all types of bad aorta. The TCA-clamp method, on the other hand, is applicable to any case, no matter how severe its calcification is. As more outcomes of TAVR surgery including the long-term ones add up, application criteria for TAVR and conventional AVR in isolated aortic valve surgery will be established.
Conclusion In this article, preoperative assessment and surgical management for bad aorta are reviewed. As seen in the case with the recent introduction of TAVR, improvement in preoperative assessment modalities and selection of a proper procedure for each case are expected to bring further progress in the outcome of cardiac surgery.
279 Conflict of interest The author has no conflict of interest to disclose with respect to this paper.
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Gen Thorac Cardiovasc Surg (2014) 62:273–281 34. Gillinov AM, Lytle BW, Hoang V, Cosgrove DM, Banbury MK, McCarthy PM, Sabik JF, Petterson GB, Smedira NG, Blackstone EH. The atherosclerotic aorta at aortic valve replacement: surgical strategies. J Thorac Cardiovasc Surg. 2000;120:957–65. 35. Aranki SF, Nathan M, Shekar P, Couper G, Rizzo R, Cohn LH. Hypothermic circulatory arrest enable aortic valve replacement in patients with unclampable aorta. Ann Thorac Surg. 2005;80: 1679–87. 36. Chung S, Park PW, Choi MS, Cho SH, Sung KI, Lee YT, Jeong JH. Surgical experience of ascending aorta and aortic valve replacement in patient with calcified aorta. Korean J Thorac Cardiovasc Surg. 2012;45:24–9. 37. Culliford AT, Colvin SB, Rohrer K, Baumann FG, Spencer FC. The atherosclerotic ascending aorta and transverse arch: a new technique to pre-vent cerebral injury during bypass: experience with 13 patients. Ann Thorac Surg. 1986;41:27–34. 38. Svensson LG, Sun J, Cruz HA, Shahian DM. Endarterectomy for calcified porcelain aorta associated with aortic valve stenosis. Ann Thorac Surg. 1996;61:149–52. 39. Stern A, Tunick PA, Culliford AT, Lachmann J, Baumann FG, Kanchuger MS, Marschall K, Shah A, Grossi E, Kronzon I. Protruding aortic arch atheromas: risk of stroke during heart surgery with and without aortic arch endarterectomy. Am Heart J. 1999;138:746–52. 40. Vogt PR, Hauser M, Schwarz U, Jenni R, Lachat ML, Zu¨nd G, Schu¨pbach RW, Schmidlin D, Turina MI. Complete thromboendarterectomy of the calcified ascending aorta and aortic arch. Ann Thorac Surg. 1999;67:457–61. 41. Wareing TH, Davila-Roman VG, Daily BB, Murphy SF, Schechtman KB, Barzilai B, Kouchoukos NT. Strategy for the reduction of stroke incidence in cardiac surgical patients. Ann Thorac Surg. 1993;55:1400–8. 42. King RC, Kanithanon C, Shockey KS, Spotnitz WD, Tribble CG, Kron IL. Replacing the atherosclerotic ascending aorta is a highrisk procedure. Ann Thorac Surg. 1998;66:396–401. 43. Kouchoukos NT, in discussion of: Gillinov AM, Lytle BW, Hoang V, Cosgrove DM, Banbury MK, McCarthy PM, Sabik JF, Petterson GB, Smedira NG, Blackstone EH. The atherosclerotic aorta at aortic valve replacement: surgical strategies. J Thorac Cardiovasc Surg 2000;120:963–964. 44. Girardi LN, Krieger KH, Mack CA, Isom OW. No-clamp technique for valve repair or replacement in patients with a porcelain aorta. Ann Thorac Surg. 2005;80:1688–92. 45. Zingone B, Gatti G, Spina A, Rauber E, Dreas L, Forti G, Pappalardo A. Current role and outcomes of ascending aortic replacement for severe nonaneurysmal aortic atherosclerosis. Ann Thorac Surg. 2010;89:429–34. 46. Zingone B, Gatti G, Rauber E, Pappalardo A, Benussi B, Dreas L. Surgical management of the atherosclerotic ascending aorta: is endoaortic balloon occlusion safe? Ann Thorac Surg. 2006;82: 1709–14. 47. Kim IS, Byun JH, Yoo BH, Kim HY, Hwang SW, Song YG. Aortic valve replacement using balloon catheter for thoracic endovascular aortic repair to patient with calcified aorta. Korean J Thorac Cardiovasc Surg. 2013;46:212–5. 48. Tajima K. How to deal with severe aortic calcification in performing aortic valve surgery. The 6th AATS/ASCVTS postgraduate course text book. 2013. p. 16–18. 49. Hatakeyama M, Ono Y, Munakata M, Itaya H. Aortic valve replacement for severely calcified aorta with SCP and deep hypotheramic circulatory arrest. Jpn J Cardiovasc Surg. 2012;41: 80–4 (Japanese). 50. Cooley DA, Norman JC, Mullins CE, Grace RR. Left ventricle to abdominal aorta conduit for relief of aortic stenosis. Cardiovasc Dis. 1975;2:376–83.
Gen Thorac Cardiovasc Surg (2014) 62:273–281 51. Cooley DA, Norman JC. Apical left ventricular-abdominal aortic composite conduits for left ventricular outflow obstructions. Cardiovasc Dis. 1978;5:112–27. 52. Brown JW, Ruzmetov M, Fiore AC, Rodefeld MD, Girod DA, Turrentine MW. Long-term results of apical aortic conduits in children with complex left ventricular outflow tract obstruction. Ann Thorac Surg. 2005;80:2301–8. 53. Cooley DA, Lopez RM, Absi TS. Apicoaortic conduit for left ventricular outflow tract obstruction: revisited. Ann Thorac Surg. 2000;69:1511–4. 54. Hirota M, Oi M, Omoto T, Tedoriya T. Apico-aortic conduit for aortic stenosis with a porcelain aorta; technical modification for apical outflow. Interact CardioVasc Thorac Surg. 2009;9:703–5. 55. Matsuyama K, Narita Y, Ueda Y. Apicoaortic valved conduit without an apical connector. Gen Thorac Cardiovas Surg. 2007;55:370–1. 56. Vassiliades TA. Off-pump apicoaortic conduit insertion for highrisk patients with aortic stenosis. Euro J Cardio-thorac Surg. 2003;23:156–8. 57. Takemura T, Tsuda Y. Apicoaortic conduit insertion for elderly patients with acquired aortic stenosis and small aortic annulus. Kyobu Geka. 2006;59:294–300 (Japanese). 58. Steen PA, Newberg L, Milde JH, Michenfelder JD. Hypothermia and barbiturates: individual and combined effects on canine cerebral oxygen consumption. Anesthesiology. 1983;58:527–32. 59. Nishi H, Mitsuno M, Ryomoto M, Miyamoto Y. Comprehensive approach for clamping severely calcified ascending aorta using computed tomography. Interact Cardiovasc Thorac Surg. 2010;10:18–20.
281 60. Ascer E, Veith FJ, Flores SA. Infrapopliteal bypasses to heavily calcified rock-like arteries: management and results. Am J Surg. 1986;152:220–3. 61. Brewster DC. Direct reconstruction for aortoiliac occlusive disease. In: Rutherford RB, editors. Vascular surgery. 3rd ed. Philadelphia: Saunders; 1989; Chap 55. 62. Carpenter JP, Berkowitz HD. A technique for suturing anastomoses involving calcified vessels. J Vasc Surg. 1992;16:494–6. 63. Hutson DG, Ginzburg E, Tabbara M, Nun˜ez AA, Zalewski M. Suturing the calcified aorta. J Vasc Surg. 1994;19(6):1098–9. 64. Kudo M, Misumi T, Koizumi K. Aortotomy and endarterectomy of the ascending aorta for aortic valve replacement in a patient with porcelain aorta. Surg Today. 2005;35:1000–3. 65. Walther T, Simon P, Dewey T, Wimmer-Greinecker G, Falk V, Kasimir MT, Doss M, Borger MA, Schuler G, Glogar D, Fehske W, Wolner E, Mohr FW, Mack M. Transapical minimally invasive aortic valve implantation: multicenter experience. Circulation. 2007;116(Suppl I):I240–5. 66. Zahn R, Schiele R, Gerckens U, Linke A, Sievert H, Kahlert P, Hambrecht R, Sack S, Abdel-Wahab M, Hoffmann E, Senges J. German transcatheter aortic valve interventions registry investigators. transcatheter aortic valve implantation in patients with ‘‘Porcelain’’ aorta (from a multicenter real world registry). Am J Cardiol. 2013;111:602–8. 67. Urbanski PP, Raad M, Wagner M, Heinz N, Reents W, Diegeler A. Cardiac surgery in patients with a porcelain aorta in the era of transcatheter valve implantation. Eur J Cardiothorac Surg. 2013;44:48–53.
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CURRENT TOPICS REVIEW ARTICLE
Bad Aorta Kazuyoshi Tajima
Received: 29 July 2013 / Published online: 18 March 2014 Ó The Japanese Association for Thoracic Surgery 2014
Abstract As its outcomes improve, cardiac surgery has been performed on more and more cases which were previously considered to be difficult to deal with. However, there are still a number of problems to be solved regarding surgery on patients with severe sclerotic lesions in the ascending aorta, which we collectively call ‘‘bad aorta’’. Concerning a preoperative assessment of the ascending aorta, our report revealed no relationship between the severity of calcification detected with a preoperative nonenhanced CT and the aortic lesion found during the surgery. Meanwhile, an intraoperative epiaortic ultrasound enables us to make high-quality evaluations of the aorta without imposing much burden on the patient. This modality may be essential for cardiac surgery. As for surgical management for bad aorta, quite a few methods have been reported to this point, but the overall operative mortality rate and cerebrovascular accident rate are relatively high, at a little \10 %, respectively. With the recent crossclamping method under short-term total circulatory arrest (TCA), however, the results are much better; these rates total around 5 %. Further improvement is expected in the outcome of cardiac surgery on bad aorta cases by establishing a modality to evaluate sclerotic lesions in the ascending aorta with epiaortic ultrasound and by selecting a proper procedure for each case. Keywords Porcelain aorta Shaggy aorta Circulatory arrest Aorta clamping Epiaortic ultrasound
This review was submitted at the invitation of the editorial committee. K. Tajima (&) Department of Cardiovascular Surgery, Nagoya Daini Red Cross Hospital, 2-9 Myoken-cho, Showa-ku, Nagoya 466-8650, Japan e-mail: [email protected]
Introduction Severe sclerosis in the ascending aorta has been increasingly encountered in cardiac surgery with the aging and the increase in hemodialysis cases among cardiac surgical patients in recent years. Since sclerotic lesions developed in the area from the ascending aorta to the aortic arch expectedly raise the risk of cerebral embolization and embolization to visceral vessels [1–4], special consideration should be given when establishing a cardiopulmonary bypass (CPB), achieving a cardiac arrest, and incising the aorta. In this article, some strategies to address such cases reported to date are reviewed, and the approach we are taking at our institution is shown. Cases discussed here are those which require the use of CPB and aortic clamping. Coronary artery bypass grafting (CABG) cases are not included because the risk stated above can be avoided using off-pump CABG which does not require CPB. Isolated mitral valve surgery is not included here either because it can be performed without an aortic incision and there is an alternative way of surgery with the heart beating. What is ‘‘bad aorta’’? Aortic sclerosis occurs as severe aortic wall calcification (Fig. 1), liquid-rich atheroma in the aorta (Fig. 2) or both. Such severe aortic sclerosis has been called by different names, e.g. ‘‘diseased aorta,’’ ‘‘shaggy aorta,’’ ‘‘porcelain aorta,’’ and ‘‘eggshell aorta’’ [5–8], and each of them has a slightly different meaning. However, since which expression is used does not make any difference in difficulty of surgery, we have collectively named any aorta with sclerotic lesions in the ascending aorta for which a standard surgical approach should be avoided ‘‘bad aorta’’ [9].
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Fig. 1 Porcelain aorta: unenhanced 3D CT shows severe calcification of the entire aorta
Fig. 2 Shaggy aorta: preoperative epiaortic ultrasound shows intimal thickening and protruding plaque inside the aorta
Assessment of the aorta A commonly used diagnostic modality to evaluate ‘‘bad aorta’’ is a preoperative unenhanced CT scanning, which
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enables us to evaluate the sclerotic type in the aorta. However, an unenhanced CT can only detect the degree of aortic wall calcification, not the presence of atheroma in the aorta. In order to detect protruding atherosclerotic plaque, contrast-enhanced CT may be useful. An enhanced dual-helical CT with thin sections has been reported to be effective, detecting 95 % of what transesophageal echocardiography (TEE) can find [10]. However, it may be unnecessarily generalized, therefore inappropriate, to use enhanced dual-helical CT as a screening for standard cardiac surgery which only focuses on the aortic root and proximal ascending aorta. TEE is said to be a relatively reliable modality which can provide accurate measurement of plaque thickness and detect mobile thrombi as well [11, 12]. The problem is that it may impose too much burden on heart disease patients if it is applied when they are awake [13]. During surgery, when patients are under anesthesia, on the other hand, epiaortic ultrasound excels TEE in providing images of the ascending aorta. The quality of images is very high and the detected location of plaques and/or calcium deposits is precise with an intraoperative epiaortic ultrasound because its transducer is placed directly on the aorta [14]. Aortic plaque detected by this technique has been reported to predict early and late complications of heart surgery, including stroke and renal insufficiency [15, 16]. After all of these considerations, an intraoperative epiaortic ultrasound is now conducted on all the cardiac surgical patients, regardless of the findings of a preoperative CT, at our institution. Now magnetic resonance imaging (MRI) is also used for the evaluation of aortic plaque in some cases. However, it is said that MR angiography tends to underestimate plaque thickness in the aortic arch because of difficulties in defining the aortic wall [17]. The advantage of MRI, according to some reports, is that it can reveal contrasts between different tissue types, identifying morphological components of the atherosclerotic plaque, such as calcification, fibrocellular tissue, lipid, and thrombus [18, 19]. Since plaque stability depends on the size of the lipid core, the thickness of the fibrous cap and inflammation within the cap, MRI can be helpful in evaluating these parameters [20]. Relationship between aortic calcification detected with preoperative CT and lesions found during surgery In order to examine whether it is possible to anticipate the presence of aortic atheroma from the aortic calcification detected with a CT, preoperative CT findings and aortic lesions (atherosclerotic plaque and/or protruding calcification) found during surgery were compared in 50 bad aorta cases at our institution. The degree of calcification in the
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Fig. 3 The degree of calcification in the ascending aortic wall detected with a preoperative CT was graded into five groups: grade 0 (no calcification, 2 cases), I (calcification in \25 % of the entire circumference, 23 cases), II (25–50 %, 14 cases), III ([50 %, 7 cases), IV (100 %, 4 cases). This indicates no relationship between the aortic calcification grade and the presence of mobile plaque and/or protruding lesions found during surgery
ascending aortic wall detected with a preoperative CT was graded into five groups, which are grade 0 (no calcification, 2 cases), grade 1 (calcification in \25 % of the entire circumference, 23 cases), grade 2 (25–50 %, 14 cases), grade 3 ([50 %, 7 cases) and grade 4 (100 %, 4 cases), and the number of the cases which actually had treatment of the aorta was counted. The percentage of the cases which needed treatment during surgery was 50 % for grade 0, 30 % for grade 1, 50 % for grade 2, 43 % for grade 3 and 50 % for grade 4, indicating no relationship between the aortic calcification grade detected preoperatively and the presence of mobile plaque and/or protruding lesions found during surgery (Fig. 3). This result shows that unenhanced CT is insufficient for the preoperative risk evaluation of aortic clamping, and accordingly, some argue that enhanced CT should be necessary [21]. However, the use of a contrast medium is not preferable since patients suffering from bad aorta are usually old. Furthermore, according to Bergman et al. [22], epiaortic ultrasound works better than CT scanning, enhanced or unenhanced, in diagnosing atherosclerosis in the ascending aorta. The author agrees with them there and believes that a preoperative enhanced CT is not essential. What should we have in mind? When the surgery requiring a cardiac arrest is performed on patients with bad aorta detected by a preoperative chest CT, the following three issues should be taken into account: first, selection of the cannulation site for a CPB; second, whether it is possible to clamp the ascending aorta safely; and third, whether incision and suture of the
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ascending aorta are possible. To make correct judgments on these issues, intraoperative epiaortic ultrasound is essential, and actually performed in all cases at our institution, regardless of the preoperative CT evaluation of the aorta. Even if a CT image shows mild or even no sclerosis, intraoperative epiaortic ultrasound detects mobile plaques inside the wall in some cases (Fig. 4). Moreover, preoperative identification of plaques and/or calcium deposits in the ascending aorta with an enhanced CT or TEE cannot really indicate their precise location, and thus whether to perform aortic cannulation or aortic clamping is often determined with intraoperative epiaortic ultrasound [22]. Use of a handheld probe provides definitive locality of aortic atheroma since the lesion is present immediately beneath the probe. In regard to epiaortic ultrasound, there have been many articles discussing the findings to be watched [3, 23–25]. The French aortic plaque in stroke (FAPS) group, for example, evaluated a large number of patients with different plaque thicknesses and found that in those with a plaque thickness [4 mm the odds ratio for stroke was significantly larger [26]. The odds ratio for a stroke in patients with 1 mm plaques was 1.0 (no increased risk); for 1–3.9 mm plaques it was 3.9; and for plaques [4 mm it was much higher, 13.8. The following findings around the proposed clamping site are the indications which we consider that urge us to take some careful approach in performing aortic cross-clamping. 1. 2. 3.
Intimal thickening of more than 3 mm. Protruding lesion. Severe calcification.
The plaque thickness has been determined based on the figures shown above, allowing some safety margin. When these findings are observed, solutions should be sought for the above-mentioned three issues.
Surgical management for bad aorta First issue If there is even the smallest doubt about finding a suitable cannulation site on the ascending aorta, an alternative site should be looked for on branches such as axillary arteries, subclavian arteries or femoral arteries without any hesitation. Since patients with bad aorta often have severe sclerosis in their femoral arteries as well and there is a danger of atheroemboli caused by retrograde perfusion through an atherosclerotic or aneurysmal descending aorta, it is better to select the right axillary artery as a cannulation site [27, 28]. An 8-mm graft sewn to the axillary artery in an end-to-side fashion ensures a sufficient perfusion flow [29].
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Fig. 4 The aorta seems to be normal in an unenhanced CT (left), but mobile plaque is observed inside the aorta in epiaortic ultrasound (right)
Second issue The following approaches have been reported to deal with the cases where an aortic clamping may cause an embolism (Table 1). Aortic valve surgery under deep hypothermic circulatory arrest (DHCA) This is an aortic valve replacement performed in a short limited time. After achieving deep hypothermia with a CPB, the circulation is arrested, followed by the incision in the ascending aorta without an aortic clamping. According to the reports by Gillinov et al., who have dealt with a large volume of such cases, the operative mortality rate was 12 % and the postoperative stroke rate was 4 %, which were relatively high. The recent report by Chung et al., however, shows excellent outcomes with no intraoperative deaths or cerebrovascular accidents. This may be because the improvement in technique has shortened the duration of the circulatory arrest. The disadvantage of this surgery under DHCA is that given time is limited. For this reason it is only applicable to isolated AVR and it is nearly impossible to perform complex surgery. Aortic endarterectomy under DHCA This is a surgical procedure which involves peeling the entire calcified area in the ascending aorta. The process up to the aortic incision is the same as in the aortic valve surgery under DHCA described above, and after peeling the calcified area, an aortic cross-clamping and standard cardiac surgery follow. Some reports on this procedure were seen until the early 2000s, but there have not been any these days. The reason for this may be the high incidence rate of stroke, which was 18.6 %. The average mortality rate obtained from all those reports, on the other hand, was not really high (3.5 %). This procedure is applicable to complex surgery because a standard procedure can be performed once the aorta is clamped.
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Ascending aorta grafting under DHCA In this procedure, a graft is anastomosed to the distal ascending aorta first, and after this anastomosed graft is clamped, standard surgery is performed. Although this has been the most popular approach, the overall mortality rate is not sufficiently low, being around 10 %. This procedure is applicable to any cardiac surgery. The approach where selective cerebral perfusion is used combined with DHCA has also been reported as a modified method [45, 49]. Surgery under balloon occlusions This procedure is performed under the aortic occlusion which is achieved by placing an occlusion balloon catheter in the ascending aorta. A balloon catheter can be inserted either antegradely or retrogradely, but it is difficult to hold the balloon in proper position. Zingone et al. [46], who have reported the largest number of these cases, mentioned that the mortality rate for isolated valve surgery was extremely high (38.5 %) and that the approach using balloon occlusion was frequently ineffective and had a higher risk of in-hospital death as well as a higher risk of stroke. We have also observed that it is very difficult to position the catheter correctly, and that it should always be made sure that the proximal brachiocephalic artery is not being occluded. This approach has been devised to deal with porcelain aorta, and is rather dangerous for the cases with mobile plaques. Other approaches Apico-aortic valved conduit (AAVC) This procedure was presented by Cooley et al. [50] in 1975. It was first devised to deal with the left ventricular outflow tract obstruction (LVOTO), and the early performances by
Gen Thorac Cardiovasc Surg (2014) 62:273–281 Table 1 Operative management of bad aorta in relevant literature and main outcomes
Method
‘Simple’ AVR under DHCA
277
Author
Year
Aortic tube grafting under DHCA
a
CVA
n
n
%
71
NA
0
0
Coselli [31]
1986
2
NA
NA
0
0
Byrne [32] Silberman [33]
1998 2002
3 8
68 72
58 38
0 0
0 0
Gillinov [34]
2000
24
72
54
3
4
17
Aranki [35]
2005
13
77
44
0
2
15
Chung [36]
2012
11
68
30
0
0
62
3
12
%
4.8
6
9.7
Culliford [37]
1986
13
66
3.5–12
0
1
7.7
Svensson [38]
1996
6
74
NA
0
1
16.7
Stern [39]
1999
43
NA
NA
0
15
34.9
Vogt [40]
1999
22
68
21
1
4.5
1
4.5
Gillinov [34]
2000
16
72
13
3
19
2
12
Aranki [35] Subtotal
2005
13 113
79
9
0 4
3.5
1 21
Wareing [41]
1993
27
NA
29
1
3.7
0
King [42]
1998
17
NA
NA
4
23.5
3
Gillinov [34]
2000
12
72
13
3
25
0
Kouchoukos [43]
2000
83
NA
NA
7
8
3
7.6 18.6 17.6 3.6
Aranki [35]
2005
44
79
27
3
6.8
6
13.5
Girardi [44]
2005
25
75
19
2
8
1
4
Zingone [45]
2010
64
72
34a
272
7
10.9
4
6.3
27
9.9
17
6.3
Gillinov [34]
2000
4
72
5
0
Zingone [46] Kim [47]
2006 2013
52b 1
75 79
0 0
13 0
25
2 0
3.8
13
22.8
2
3.5
57
0
Others Inspect and cross-clamp
Gillinov [34]
2000
6
NA
NA
0
TCA-Clamp
Tajima [48]
2013
96
70
3.6
3
3.2
2
2.1 2
Under antegrade and/or retrograde brain perfusion
b
Operative mortality
1
Subtotal HCA hypothermic circulatory arrest, CVA cerebrovascular accident, NA not available
HCA (min)
1984
Subtotal Balloon occlusion
Age
Jacobowitz [30]
Subtotal Aortic endarterectomy under DHCA
Patients (n)
Including isolated CABG
Cooley [51] himself on 23 cases resulted in three early deaths (13 %). Cooley’s approach has been largely replaced with the Ross or Ross–Konno procedure since the 1990s because late complications caused primarily by conduit tissue valve dysfunction were frequent in children [52]. It has not been recognized as a standard procedure for about 25 years. However, as the number of cardiac surgical cases with severe sclerosis increases, this procedure has been spotlighted again [53], which Cooley himself described as ‘‘revisited’’. The improvement in prosthetic valves and
0
Subtotal
102
3
2.9
2
Total
606
50
8.3
48
7.9
conduit suturing, which contributed to the solution to the long-term problems, such as left ventricular pseudoaneurysm and prosthetic valve dysfunction, also seems to be behind the revaluation of Cooley’s work. Now AAVC often appears in reports on porcelain aorta cases although it was first devised to deal with LVOTO [54, 55]. The advantage of this procedure is that it can be performed without touching the ascending aorta and that it does not require a cardiac arrest. It also can be done without a CPB [56]. Takemura et al. [57] performed AAVC surgery on 7 elderly patients, who were all around 80 years old, between
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278
Fig. 5 Procedures performed in TCA-clamp method
2001 and 2005. No operative deaths were reported, but there was one case of descending aortic dissection, which consequently raised the following issues: the condition of the descending aorta should be closely watched; there is a risk of cerebral embolism caused by retrograde perfusion through the sclerotic descending aorta; and there is a possibility of an incidence of mitral regurgitation coming from a displacement of the mitral valve papillary muscle as a long-term outcome. This procedure is limited to aortic valve stenosis cases and not applicable to complex surgery. Cross-clamping under short-time total circulatory arrest (TCA-Clamp) In 2000, Gillinov et al. reported that there were no operative deaths or strokes in 6 patients for whom the aorta was cross-clamped at a safe spot revealed in the inspection of the aorta during HCA. The TCA-Clamp method is an improved version of Gillinov’s. First, the circulation is arrested temporarily under mild hypothermia (31–33 °C), followed by a close internal inspection of the ascending aorta from the partial transverse incision for AVR. After mobile plaques or protruding lesions which may cause an embolism are quickly cleared by a device such as a cavitron ultrasonic surgical aspirator (CUSA), the circulation is restarted, and then the aorta is clamped expelling the remaining debris and air [9] (Fig. 5). The target temperature for hypothermic state depends on the epiaortic ultrasound findings. When aortic clamping is assumed to be possible without any treatment to prepare a safe clamping site, the temperature with mild hypothermia is low enough. If the time needed for the treatment of the aortic lesions is estimated to be long, moderate hypothermia (25–30 °C) will be adopted. When the brain
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temperature drops as low as 28 °C, the cerebral metabolic rate for oxygen (CMRO2) decreases to a half, which allows us to totally arrest the circulation for about 10 min [58]. The longest time needed for intra-aortic treatment under TCA was 7 min in our cases. We performed this procedure on 96 patients, the average age of whom was 70 years old. The results were satisfactory. The average duration of the circulatory arrest was 3.6 min. There were 3 cases of hospital death (3.2 %) and 2 cases of stroke (2.1 %), but one of them was only transient and the patient fully recovered [48]. This procedure can be applied to not only porcelain aorta but also any case involving bad aorta. Since the cardiac procedure can be performed in a conventional manner once the aorta is safely clamped, it is also applicable to operations other than AVR. The problem with this method is that the positive predictive value is low despite the high sensitivity. Of the 50 cases which were found positive with epiaortic ultrasound, as many as 30 cases had only light intimal lesions and the aorta was safe to crossclamp. In those cases, an inspection was made but the procedure to prepare a clamping site was determined to be unnecessary. Meanwhile, Nishi et al. successfully cross-clamped the artery by placing the clamp parallel to the calcified lesion. Eleven patients who had calcification in \75 % of the entire circumference of the ascending aorta underwent surgery in that manner. None of them had a postoperative neurological complication, according to them [59]. We also cross-clamp the aorta parallel to the calcified lesion in many of the cases for which the preparation of a safe clamping site has been determined to be unnecessary. However, with the TCA-clamp method, this technique is performed much more safely because the aorta is clamped under a direct internal observation and with a clamp simulation. Third issue When there is severe calcification along the incision line, aortotomy and suture of the aorta become difficult to perform. Many reports were published in the past on techniques in suturing calcified vessels. Ascer et al. [60] described the techniques of crushing the arterial wall to fragment the calcification. Others have suggested endarterectomy before suturing because the calcification is confined to the intima and media [61]. Carpenter et al. [62], Hutson et al. [63] and others made holes for suturing using a 23-gauge hypodermic needle as drill bits. According to Kudo et al., debris was not released inside the aorta if an oscillating saw was used in making an incision. They first performed a 1-cm-wide endarterectomy of the calcified intima, and sutured the incision with a bovine pericardial strip as a reinforcement. They reported one successful case where progress was satisfactory with no brain complication [64].
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Our view toward the safe suture is the same as Carpenter et al.’s. At our institution the aorta is sutured after achieving endarterial decalcification only along the suture line using CUSA, which has been successful.
Problem at issue The TCA-clamp method is considered to be an excellent procedure which is technically easy to perform and involves very little risk. However, the positive predictive value obtained from epiaortic ultrasound is so low that in many cases inspections are not followed by a treatment of the aorta. Improving the positive predictive value is one issue to be addressed. Although a combination of some preoperative enhanced CT scans may help us make better judgments, it has the risk of imposing too much burden on patients. This does not make any sense because the TCAclamp itself is a minimally invasive procedure. Accuracy in judgment should be improved with better analysis of intraoperative findings. Strength of the aortic wall after the treatment such as decalcification by CUSA is also an issue to be studied. Of the 41 cases of aortic wall treatment done with the TCAclamp method, no incidence of pseudoaneurysm at the treatment site has been encountered at our institution to this point during the follow-up period, which is 12 years at the longest. However, the follow-up period is still short, and thus it is necessary to continue to watch the progress closely. The recent introduction of transcatheter aortic valve replacement (TAVR) seems to bring quite a few successful outcomes regarding the treatment of porcelain aorta in isolated AVR surgery [65–67]. However, it is assumed to be rather risky when dealing with shaggy aorta. Therefore, it may not be applicable to all types of bad aorta. The TCA-clamp method, on the other hand, is applicable to any case, no matter how severe its calcification is. As more outcomes of TAVR surgery including the long-term ones add up, application criteria for TAVR and conventional AVR in isolated aortic valve surgery will be established.
Conclusion In this article, preoperative assessment and surgical management for bad aorta are reviewed. As seen in the case with the recent introduction of TAVR, improvement in preoperative assessment modalities and selection of a proper procedure for each case are expected to bring further progress in the outcome of cardiac surgery.
279 Conflict of interest The author has no conflict of interest to disclose with respect to this paper.
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