Gen Thorac Cardiovasc Surg DOI 10.1007/s11748-014-0396-8
ORIGINAL ARTICLE
The calcified ascending aorta in aortic valve replacement: surgical strategies and results Hiroshi Baba • Yoshihiro Goto • Shinji Ogawa Yutaka Koyama • Yasuhide Okawa
•
Received: 19 September 2013 / Accepted: 18 March 2014 Ó The Japanese Association for Thoracic Surgery 2014
Abstract Purpose Calcification in the ascending aorta may constitute a major problem during aortic valve replacement (AVR). We examined the distributions of calcification and the associated operative strategies. Materials and methods Between 1999 and 2012, 207 consecutive, elderly patients underwent isolated AVR at our center. Computed tomographic scan data were available for all patients, and 105 were found to have at least one segment of calcification. Aortic calcifications were based on the section of the aorta that was calcified: distal, middle, and proximal of the ascending aorta. Results Forty-six patients had calcification in the distal zone. In these patients, conventional cannulation was performed in 26 patients, with an associated in-hospital mortality of 7.7 %. Arterial cannulation site was changed from the ascending aorta to somewhere in 20 patients (including other aortic sites in 9 patients, femoral artery in 7 patients, and both femoral and innominate arteries in 4 patients), without any patient deaths. Middle zone calcifications were observed in 70 patients: 63 underwent conventional crossclamping with particular care (7.9 % mortality), 5 underwent cross-clamping under direct vision during hypothermic circulatory arrest, and 2 underwent balloon occlusion. None of the patients undergoing substitute cross-clamping died. Proximal calcifications were observed in 66 patients;
47 patients underwent conventional transverse aortotomy, with an associated mortality of 8.5 %. Conclusion Although the 8.3 % mortality rate in patients undergoing conventional procedures was not negligible, it was lower than the expected 25.9 % estimated by the patient EuroSCOREs. The conventional procedure results are reasonable, but may require a substitute procedure in some cases. Keywords Calcified aorta Distribution of calcification Aortic valve replacement Hypothermic circulatory arrest Endarterectomy
Introduction Atherosclerotic changes in the ascending aorta constitute a major problem during aortic valve replacement (AVR). Because of the diffuse, circumferential, plate-like calcification of the ascending aorta, conventional cannulation, cross-clamping, and aortotomy need to be modified to reduce morbidity and mortality [1, 2]. The optimal approach for AVR in such patients is controversial [3, 4]. The purpose of this study was to examine the distribution of calcification, operative strategies, and results of AVR in elderly patients with calcified ascending aortas.
Patients and methods Presented at The 65th Annual Scientific Meeting of The Japanese Association for Thoracic Surgery. H. Baba (&) Y. Goto S. Ogawa Y. Koyama Y. Okawa Department of Cardio Vascular Surgery, Toyohashi Heart Center, 21-1 Gobudori, Oyamacho, Toyohashi, Aichi, Japan e-mail: [email protected]
From May 1999 through April 2012, 207 consecutive elderly patients (C70 years) underwent isolated AVR at Toyohashi (Japan) Heart Center. The aorta of each patient was evaluated by non-contrast computed tomography (CT) in order to evaluate possible cannulation or cross-clamping sites in the ascending aorta or aortic arch. About 105
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(50.7 %) patients were identified with mild to severe calcification in the aorta by non-contrast CT (calcification group). Patients having small and/or scattered calcification were included in calcification group. About 102 (49.3 %) patients were not identified with any calcification. The ascending aorta was divided into 3 zones: distal (cannulation site, vicinity of the brachiocephalic artery divergence, 3 cm), middle (cross-clamping site, between the distal and proximal zones), and proximal (aortotomy site, from 3 cm distal to the sinotubular junction to the sinus of Valsalva). Operative procedures After standard anesthetic preparation, a median sternotomy exposed the ascending aorta, aortic arch, and heart. Preoperative CT scans, digital palpitations, and epiaortic ultrasound evaluations confirmed the diagnosis of calcified aorta. Aortic cannulation was the preferred method if a plaque-free and soft area was identified. Alternatively, femoral arteries were used. During the operative procedures, axillary cannulation was not necessary in any patient. The right atrium was cannulated directly for venous drainage, whereas bicaval cannulations were utilized to facilitate the administration of retrograde cerebral perfusion during hypothermic circulatory arrest (HCA). Patients were then placed on cardiopulmonary bypass, and a right superior pulmonary vein vent was placed. In each case, the surgeon chose the most suitable and safe strategy. The following strategies were used at the site of the cross-clamping. Conventional cross-clamp A soft cross-clamp was placed on the ascending aorta with particular care to orientate the clamp parallel to the calcification. The ascending aorta was opened, and AVR was performed. Balloon occlusion The patient was cooled to an esophageal temperature of approximately 28 °C. Selective cerebral perfusion was added via the innominate and left carotid arteries. Once the appropriate temperature was reached, circulatory arrest was initiated with the patient in a steep Trendelenburg position. During HCA, the ascending aorta was opened and the aorta was balloon occluded (Fig. 1). Thereafter, cardiopulmonary bypass was resumed, and the AVR was performed during rewarming. Cross-clamping under direct vision Patients were cooled to an esophageal temperature of approximately 25 °C. Once the appropriate temperature
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Fig. 1 Balloon occlusion: Patient was cooled to an esophageal temperature of approximately 28 °C. Selective cerebral perfusion was added via the innominate and left carotid arteries. Once the appropriate temperature was reached, circulatory arrest was initiated with the patient in a steep Trendelenburg position. During HCA, the ascending aorta was opened and the aorta was balloon occluded
was reached, circulatory arrest was initiated with the patient in a steep Trendelenburg position. During hypothermic circulatory arrest, the ascending aorta was opened and retrograde cerebral perfusion was started. When the ascending aorta was inspected from inside and a suitable site for cross-clamping was identified, the aorta was carefully cross-clamped. In patients with a protruding or mobile atheroma, debridement or endarterectomy was performed at the subsequent cross-clamp site. After circulation was slowly restarted and any debris was washed out, the aorta was cross-clamped. Cardiopulmonary bypass was resumed, and AVR was performed during the rewarming. Finally, the aorta was closed with double sutures. Data analysis Continuous variables are expressed as means ± standard deviations. Categorical data are given as proportions.
Results Patients’ demographic data are described in Table 1. Significantly, more patients had diabetes in the calcified group than in the group without calcifications (16.2 vs. 3.9 %, p = 0.007); the average EuroSCORE was also higher in the calcified group as compared to the non-calcified group (27.7 ± 20.3 vs. 21.0 ± 16.8, p = 0.01). The operative results are shown in Table 2. The mean operative time was longer for the patients in the calcified group than for those in the non-calcified group (247.4 ± 54.2
Gen Thorac Cardiovasc Surg
vs. 230.5 ± 45.5 min, p = 0.04). The rates of in-hospital deaths were significantly higher in the calcified group than in the non-calcified group (6.7 vs. 0 %, p = 0.02). In the calcified group, 7 in-hospital deaths occurred; the causes of death were stroke (2 patients), aortic dissection (1 patient), infection (1 patient), arrhythmia (1 patient), non-occlusive mesenteric ischemia (1 patient), and prosthetic valve dysfunction (1 patient), as shown in Table 3. In one case, one of
the two cerebral infarctions observed was extensive, whereas in another case, an infarction was noted in the left temporal lobe. The extensive cerebral infarction might be associated with multiple emboli due to cross-clamping or cannulation, and the temporal lobe cerebral infarction might be caused by cannulation. In the case with aortic dissection, rupture of the aortic dissection occurred at the site of aortic closure and the influence of cross-clamping or cannulation was not important.
Table 1 Patients characteristics Calc. n = 105
Non-calc. n = 102
p value 0.07
Age (years)
76.5 ± 4.4
77.0 ± 4.2
76.0 ± 4.5
Male (%/n)
39.1/81
40.0/42
38.2/39
0.9
Creatinine (mg/dl)
1.2 ± 1.4
1.3 ± 1.7
1.0 ± 0.9
0.2
Hypertension (%/n)
47.8/99
51.4/54
44.1/45
0.4
Diabetes (%/n)
10.1/21
16.2/17
3.9/4
0.007
Hemodialysis (%/n)
3.4/7
4.7/5
2.0/2
0.4
PAD (%/n)
10.1/21
16.2/17
3.9/4
0.007
Stroke (%/n)
5.3/11
6.7 %/7
3.9/4
0.5
IHD (%/n)
27.1/56
33.3/35
20.6/21
0.06
Maximum Ao PG (mmHg)
72.7 ± 26.0
71.3 ± 23.1
74.5 ± 29.7
0.5
Ao area (cm2)
0.6 ± 0.2
0.59 ± 0.20
0.58 ± 0.17
0.9
PAWP (mmHg)
14.2 ± 8.1
13.6 ± 8.2
14.9 ± 7.9
0.4
EF (%)
55.2 ± 13.0
56.4 ± 13.1
53.9 ± 12.7
0.2
NYHA class
2.0 ± 0.7
2.1 ± 0.7
2.0 ± 0.7
0.9
EuroSCORE (%)
24.4 ± 18.9
27.7 ± 20.3
21.0 ± 16.8
0.011
PAD peripheral arterial disease, IHD ischemic heart disease, PAWP pulmonary artery wedge pressure, EF ejection fraction
Distribution of calcification CT scan data were available for 207 patients who had isolated AVR; 105 had at least one segment of calcification. As shown in Table 4, 46 of the 105 patients with calcifications demonstrated calcifications in the distal portion of their aortas, 70 patients had calcification in the middle portions, 66 patients had calcification in the proximal portions, and 30 patients had calcification of their entire ascending aortas. Calcification in the distal zone (cannulation management) Distal aortic calcification was observed in 46 patients (Table 5). Of the 46 patients, conventional cannulations were performed in 26 patients; the cannulation site was moved to another favorable aortic site (9 patients), the femoral artery (7 patients), or to both the femoral and innominate arteries (4 patients). Axillary cannulation was not necessary in any of the patients. Of the 26 patients undergoing conventional cannulation, 2 died prior to hospital discharge (Table 3). None of the patients undergoing substitute cannulation died during hospitalization or suffered a stroke.
Table 2 Operative results
Operation (min)
239.0 ± 50.6
Calc. n = 105
Non-calc. n = 102
247.4 ± 54.2
230.5 ± 45.5
p value 0.04
CPB (min)
125.9 ± 30.5
130.5 ± 32.0
121.3 ± 28.3
0.06
Cross-clamping (min)
85.3 ± 24.8
89.1 ± 27.1
81.4 ± 21.3
0.06
Stroke (%/n)
2.4/5
1.9/2
2.9/3
0.40
DWI
1.4/3
2.9/3
0
Renal failure
4.3/9
4.8/5
3.9/4
[0.99
LOS Arrhythmia
5.8/12 2.9/6
5.7/6 2.9/3
5.9/6 2.9/3
[0.99 [0.99
Hospital death (%/n)
3.4/7
6.7/7
0
0.25
0.02
DWI deep wound infection, renal failure aggravation of the renal function (creatinine [2 mg/dl), LOS low output syndrome, arrhythmia ventricular fibrillation, ventricular flutter
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Gen Thorac Cardiovasc Surg Table 3 Hospital death Euro SCORE
Distribution
Cannulation
Cross-clamp
Incision
Cause of death
Case 1
53
Proximal ? middle ? distal
Conventional
Conventional
Substitute
Stroke
Case 2
53
Proximal
Conventional
Conventional
Conventional
Infection
Case 3
5
Proximal
Conventional
Conventional
Conventional
Vf
Case 4
18
Proximal ? middle ? distal
Conventional
Conventional
Conventional
NOMI
Case 5
20
Proximal ? middle
Conventional
Conventional
Conventional
stroke
Case 6
40
Middle
Conventional
Conventional
Conventional
Valve disfunction
Case 7
45
Middle
Conventional
Conventional
Conventional
DA
Vf ventricular fibrillation, NOMI non-occlusive mesenteric ischemia, DA aortic dissection
Table 4 Distribution of calcification n
Stroke (%/n)
Complication (%/n)
Mortality (%/n)
EuroSCORE
Distal
5
0/0
0/0
0/0
15.2
Middle
30
0/0
10.0/3
6.7/2
26.4
Proximal
23
0/0
13.0/3
8.7/2
29.1
Distal ? middle
4
0/0
0/0
0/0
33.4
Distal ? proximal
7
0/0
0/0
0/0
16.4
Middle ? proximal
6
16.7/1
16.7/1
16.7/1
11.9
30
3.3/1
3.3/6
6.6/2
34.9
Entire
Table 5 Strategy in the site of cannulation (n = 46) n Conventional substitute
26
Table 7 Strategy in the site of aortotomy (n = 66)
Stroke (%/n)
Mortality
n
3.8/1
7.7/2
Conventional site
Femoral artery
7
0
0
Conventional site ? EA
Femoral artery ? innominate artery
4
0
0
Substitute site
Right site of ascending aorta
4
0
0
Substitute site ? EA
Aortic arch
3
0
0
Proximal site of ascending aorta
2
0
0
Table 6 Strategy in the site of cross-clamping (n = 70)
Conventional
n
Stroke (%/n)
Mortality
63
3.2/2
7.9/5
Under direct vision with/without EA
5
0
0
Balloon
2
0
0
EA endarterectomy
Calcification in the middle zone (cross-clamping management) Mid-aorta calcification was present in 70 patients (Table 6). The majority of these patients underwent conventional cross-clamping. Cross-clamping was performed in the ascending aorta, taking particular care to orientate the clamp parallel to the calcification (63 patients). In 5
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Stroke (%/n)
Mortality (%/n)
45
0
8.9/4
2
0
0
18 1
11.1/2
5.6/1
0
0
EA endarterectomy
patients, cross-clamping was performed under direct vision during HCA. This strategy included endarterectomy (2 patients). Balloon occlusion was performed in another 2 patients. Of the 63 patients undergoing conventional crossclamping, 5 died in-hospital (Table 3) and 2 suffered an early stroke. None of the patients undergoing substitute cross-clamping died in-hospital or suffered a stroke. Calcification in the proximal zone (aortotomy management) Table 7 describes the 66 patients with calcification at the aortotomy site. Conventional transverse aortotomy was performed in 47 patients (4 died in-hospital), with additional endarterectomy being performed in 2 patients. Substitute aortotomy was performed in 19 patients. Of the 19 patients, one patient died in-hospital and another survived an early stroke.
Gen Thorac Cardiovasc Surg
Discussion Intraoperative epiaortic ultrasound is a useful test for detecting atherosclerotic changes in the ascending aorta, intraoperatively [5]. However, surgeons are able to recognize this difficult situation only following the sternotomy. On the other hand, non-contrast CT scans identifies areas of aortic calcification. Computed tomographic scans can be performed before an elective sternotomy, and potential alterations of operative approach and any revised risk can then discussed with patients in the preoperative setting [6]. Computed tomographic scans provide reproducible and more accurate information regarding both the circumferential severity of the calcification and the proximal and distal extent of the calcification [5, 7]. Computed tomographic scans also help to determine the appropriate operative strategy, facilitating a more aggressive strategy for avoiding calcified areas and reducing the risk of stroke [8]. The presence of a calcified ascending aorta in AVR patients poses a serious dilemma for the surgeon because it may preclude safe cannulation and cross-clamping and create difficulties for aortotomy and suturing. Furthermore, the increased risks of cerebral embolization, aortic dissection, and mural laceration are serious problems [1, 2]. Therefore, several alternative methods, including apicoaortic conduit, deep HCA, aortic replacement, endoaortic balloon occlusion, and cross-clamping under direct vision, have been described for dealing with the calcified aorta. Nishi et al. described cross-clamping wherein particular attention is paid to orienting the clamp parallel to the calcification, based on the preoperative CT scan. They were able to routinely perform this procedure without increasing the risk of stroke or mortality [9]. In our experience, 2 patients who underwent conventional crossclamping, ensuring that the clamp was parallel to the calcification, suffered from cerebral infarction, suggesting that additional, meticulous studies may be necessary. Occluding the ascending aorta with a balloon catheter has also been proposed as a substitute for cross-clamping, on the assumption that it would be less traumatic and less prone to causing systemic emboli [10]. However, Bartolo et al. found that balloon occlusion was frequently ineffective; in 19.2 % of patients, the balloon had to be replaced by an ordinary cross-clamp because of incomplete occlusion, hindered exposure, or balloon rupture [11]. We have used this technique on a few cases but have found that the balloon can migrate, causing bleeding. Deep HCA, without cross-clamping, is possibly the simplest approach and can be performed with an acceptable mortality [12–14]. However, the associated time constraints may negatively affect the surgeon’s accuracy, increasing the risk of cerebral events in elderly patients [7]. Takami et al. reported a technique of cross-clamping during short-term, moderate
HCA after internal inspection or endarterectomy. In their study, they did not report any mortality or morbidity [15]. Similarly, in the current study, we did not observe associated strokes or mortality. Aortic replacement, before AVR, is a more radical approach. This technique avoids any aortic manipulation prior to deep HCA, cross-clamping the graft occurs following distal anastomosis; the AVR was carried out during the rewarming phase. The replacement of the diseased aorta eliminates the risk of aneurysmal formation and embolization. However, elderly patients requiring extensive procedures and prolonged periods on bypass have a substantially increased risk of mortality and morbidity [7, 16], but the results are acceptable [3, 7, 16, 17]. Aortic cannulation, when feasible, remains the preferred cannulation route. Moving the cannulation site away from the calcified sites may become a choice when the disease is well localized. These patients often have severe atherosclerosis of the descending aorta and peripheral vasculature and are at a high risk of retrograde embolism [7, 16]. If the femoral arteries are not suitable for cannulation because severe peripheral vascular disease or a major disease in the descending thoracic aorta preclude safe retrograde perfusion, the axillary artery is easily approached through a subclavian incision, if free from substantial disease [12, 18]. Aortic endarterectomy is useful in this setting. However, the potential for aneurysmal degeneration of the endarterectomized aorta remains unknown. In the present study, as well as in others described here, the mortality rates were low in patients undergoing the substitute techniques, supporting the safety of these techniques. Although the 8.3 % mortality rate observed in patients undergoing the conventional procedure was not negligible, it was lower than the expected 25.9 % estimated by the patient EuroSCOREs. Considering that the conventional procedure involves a less invasive approach, the conventional procedure appears to be sufficient for highrisk patients. Limitation This study was an observational clinical study. Although epiaortic echocardiography is now used routinely in the evaluation of patients having calcified aortas, in the current series such, patients were in the minority. In addition, the surgeon chose the operative techniques in a non-randomized fashion.
Conclusion Aortic valve replacement in patients with calcified ascending aortas is associated with increased operative
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morbidity and mortality. Although the conventional procedures provide reasonable results, according to the situation, the alternative techniques should be used properly. Conflict of interest interest.
All of the authors do not have the conflicts of
References 1. Buz S, Pasic M, Unbehaun A, Unbehaun A, Drews T, Dreysse S, Kukucka M, et al. Trans-apical aortic valve implantation in patients with severe calcification of the ascending aorta. Eur J Cardiothorac Surg. 2011;40:463–8. 2. Blauth CI, Cosgrove DM, Webb BW, Ratliff NB, Boylan M, Piedmonte MR, et al. Atheroembolism from the ascending aorta. An emerging problem in cardiac surgery. J Thorac Cardiovasc Surg. 1992;103:1104–11. 3. Gillinov AM, Lytle BW, Hoang V, Cosgrove DM, Banbury MK, McCarthy PM, et al. The atherosclerotic aorta at aortic valve replacement: surgical strategies and results. J Thorac Cardiovasc Surg. 2000;120:957–65. 4. Zingone B, Rauber E, Gatti G, Pappalardo A, Benussi B, Forti G, et al. Diagnosis and management of severe atherosclerosis of the ascending aorta and aortic arch during cardiac surgery; focus on aortic replacement. Eur J Cardiothorac Surg. 2007;31:990–7. 5. Zingone B, Rauber E, Gatti G, Pappalardo A, Benussi B, Dreas L, et al. The impact of epiaortic ultrasonographic scanning on the risk of perioperative stroke. Eur J Cardiothorac Surg. 2006; 29:720–8. 6. Nishi H, Mitsuno M, Tanaka H, Ryomoto M, Fukui S, Miyamoto Y. Who needs preoperative routine chest computed tomography for prevention of stroke in cardiac surgery? Interact Cardiovasc Thorac Surg. 2010;11:30–3. 7. Aranki SF, Nathan M, Shekar P, Couper G, Rizzo R, Cohn LH. Hypothermic circulatory arrest enables aortic valve replacement in patients with unclampable aorta. Ann Thorac Surg. 2005; 80:1679–87.
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8. Lee R, Matsutani N, Polimenakos AC, Levers LC, Lee ML, Johnson RG. Preoperative noncontrast chest computed tomography identifies potential aortic emboli. Ann Thorac Surg. 2007;84:38–42. 9. 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. 10. Erath HG, Stoney WS. Balloon catheter occlusion of the ascending aorta. Ann Torac Surg. 1983;35:560–1. 11. Kayatta MO, Ahmed S, Hammel JA, Femandez F, Pickens A, Miller D, et al. Surgical biopsy of suspected interstitial lung disease is superior to radiographic diagnosis. Ann Thorac Surg. 2013;96:399–401. 12. Byrne JG, Aranki SF, Cohn LH. Aortic valve operations under deep hypothermic circulatory arrest for the porcelain aorta: ‘‘NoTouch’’ technique. Ann Thorac Surg. 1998;65:1313–5. 13. Jacobowitz IJ, Rose DM, Shevede K, Cunningham JN. Use of profound hypothermia and circulatory arrest for the calcified aorta. Chest. 1984;85:288–9. 14. Coselli JS, Crowford ES. Aortic valve replacement in the patient with extensive calcification of the ascending aorta (the porcelain aorta). J Thorac Cardiovasc Surg. 1986;91:184–7. 15. Takami Y, Tajima K, Terazawa S, Okada N, Fujii K, Sakai Y. Safer aortic crossclamping during short-term moderate hypothermic circulatory arrest for cardiac surgery in patients with a bad ascending aorta. J Thorac Cardiovasc Surg. 2009;137:875–80. 16. 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. 17. Zingone B, Gatti G, Spina A, Rauber E, Dreas L, Forti G, et al. Current role and outcomes of ascending aortic replacement for severe nonaneurysmal aortic atherosclerosis. Ann Thorac Surg. 2010;89:429–34. 18. Svensson LG, Blackstone EH, Rajeswaran J, Sabik JF, Lytle BW, McCarthy PM, et al. Does the arterial cannulation site for circulatory arrest influence stroke risk? Ann Thorac Surg. 2004;78: 1274–84.
ORIGINAL ARTICLE
The calcified ascending aorta in aortic valve replacement: surgical strategies and results Hiroshi Baba • Yoshihiro Goto • Shinji Ogawa Yutaka Koyama • Yasuhide Okawa
•
Received: 19 September 2013 / Accepted: 18 March 2014 Ó The Japanese Association for Thoracic Surgery 2014
Abstract Purpose Calcification in the ascending aorta may constitute a major problem during aortic valve replacement (AVR). We examined the distributions of calcification and the associated operative strategies. Materials and methods Between 1999 and 2012, 207 consecutive, elderly patients underwent isolated AVR at our center. Computed tomographic scan data were available for all patients, and 105 were found to have at least one segment of calcification. Aortic calcifications were based on the section of the aorta that was calcified: distal, middle, and proximal of the ascending aorta. Results Forty-six patients had calcification in the distal zone. In these patients, conventional cannulation was performed in 26 patients, with an associated in-hospital mortality of 7.7 %. Arterial cannulation site was changed from the ascending aorta to somewhere in 20 patients (including other aortic sites in 9 patients, femoral artery in 7 patients, and both femoral and innominate arteries in 4 patients), without any patient deaths. Middle zone calcifications were observed in 70 patients: 63 underwent conventional crossclamping with particular care (7.9 % mortality), 5 underwent cross-clamping under direct vision during hypothermic circulatory arrest, and 2 underwent balloon occlusion. None of the patients undergoing substitute cross-clamping died. Proximal calcifications were observed in 66 patients;
47 patients underwent conventional transverse aortotomy, with an associated mortality of 8.5 %. Conclusion Although the 8.3 % mortality rate in patients undergoing conventional procedures was not negligible, it was lower than the expected 25.9 % estimated by the patient EuroSCOREs. The conventional procedure results are reasonable, but may require a substitute procedure in some cases. Keywords Calcified aorta Distribution of calcification Aortic valve replacement Hypothermic circulatory arrest Endarterectomy
Introduction Atherosclerotic changes in the ascending aorta constitute a major problem during aortic valve replacement (AVR). Because of the diffuse, circumferential, plate-like calcification of the ascending aorta, conventional cannulation, cross-clamping, and aortotomy need to be modified to reduce morbidity and mortality [1, 2]. The optimal approach for AVR in such patients is controversial [3, 4]. The purpose of this study was to examine the distribution of calcification, operative strategies, and results of AVR in elderly patients with calcified ascending aortas.
Patients and methods Presented at The 65th Annual Scientific Meeting of The Japanese Association for Thoracic Surgery. H. Baba (&) Y. Goto S. Ogawa Y. Koyama Y. Okawa Department of Cardio Vascular Surgery, Toyohashi Heart Center, 21-1 Gobudori, Oyamacho, Toyohashi, Aichi, Japan e-mail: [email protected]
From May 1999 through April 2012, 207 consecutive elderly patients (C70 years) underwent isolated AVR at Toyohashi (Japan) Heart Center. The aorta of each patient was evaluated by non-contrast computed tomography (CT) in order to evaluate possible cannulation or cross-clamping sites in the ascending aorta or aortic arch. About 105
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(50.7 %) patients were identified with mild to severe calcification in the aorta by non-contrast CT (calcification group). Patients having small and/or scattered calcification were included in calcification group. About 102 (49.3 %) patients were not identified with any calcification. The ascending aorta was divided into 3 zones: distal (cannulation site, vicinity of the brachiocephalic artery divergence, 3 cm), middle (cross-clamping site, between the distal and proximal zones), and proximal (aortotomy site, from 3 cm distal to the sinotubular junction to the sinus of Valsalva). Operative procedures After standard anesthetic preparation, a median sternotomy exposed the ascending aorta, aortic arch, and heart. Preoperative CT scans, digital palpitations, and epiaortic ultrasound evaluations confirmed the diagnosis of calcified aorta. Aortic cannulation was the preferred method if a plaque-free and soft area was identified. Alternatively, femoral arteries were used. During the operative procedures, axillary cannulation was not necessary in any patient. The right atrium was cannulated directly for venous drainage, whereas bicaval cannulations were utilized to facilitate the administration of retrograde cerebral perfusion during hypothermic circulatory arrest (HCA). Patients were then placed on cardiopulmonary bypass, and a right superior pulmonary vein vent was placed. In each case, the surgeon chose the most suitable and safe strategy. The following strategies were used at the site of the cross-clamping. Conventional cross-clamp A soft cross-clamp was placed on the ascending aorta with particular care to orientate the clamp parallel to the calcification. The ascending aorta was opened, and AVR was performed. Balloon occlusion The patient was cooled to an esophageal temperature of approximately 28 °C. Selective cerebral perfusion was added via the innominate and left carotid arteries. Once the appropriate temperature was reached, circulatory arrest was initiated with the patient in a steep Trendelenburg position. During HCA, the ascending aorta was opened and the aorta was balloon occluded (Fig. 1). Thereafter, cardiopulmonary bypass was resumed, and the AVR was performed during rewarming. Cross-clamping under direct vision Patients were cooled to an esophageal temperature of approximately 25 °C. Once the appropriate temperature
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Fig. 1 Balloon occlusion: Patient was cooled to an esophageal temperature of approximately 28 °C. Selective cerebral perfusion was added via the innominate and left carotid arteries. Once the appropriate temperature was reached, circulatory arrest was initiated with the patient in a steep Trendelenburg position. During HCA, the ascending aorta was opened and the aorta was balloon occluded
was reached, circulatory arrest was initiated with the patient in a steep Trendelenburg position. During hypothermic circulatory arrest, the ascending aorta was opened and retrograde cerebral perfusion was started. When the ascending aorta was inspected from inside and a suitable site for cross-clamping was identified, the aorta was carefully cross-clamped. In patients with a protruding or mobile atheroma, debridement or endarterectomy was performed at the subsequent cross-clamp site. After circulation was slowly restarted and any debris was washed out, the aorta was cross-clamped. Cardiopulmonary bypass was resumed, and AVR was performed during the rewarming. Finally, the aorta was closed with double sutures. Data analysis Continuous variables are expressed as means ± standard deviations. Categorical data are given as proportions.
Results Patients’ demographic data are described in Table 1. Significantly, more patients had diabetes in the calcified group than in the group without calcifications (16.2 vs. 3.9 %, p = 0.007); the average EuroSCORE was also higher in the calcified group as compared to the non-calcified group (27.7 ± 20.3 vs. 21.0 ± 16.8, p = 0.01). The operative results are shown in Table 2. The mean operative time was longer for the patients in the calcified group than for those in the non-calcified group (247.4 ± 54.2
Gen Thorac Cardiovasc Surg
vs. 230.5 ± 45.5 min, p = 0.04). The rates of in-hospital deaths were significantly higher in the calcified group than in the non-calcified group (6.7 vs. 0 %, p = 0.02). In the calcified group, 7 in-hospital deaths occurred; the causes of death were stroke (2 patients), aortic dissection (1 patient), infection (1 patient), arrhythmia (1 patient), non-occlusive mesenteric ischemia (1 patient), and prosthetic valve dysfunction (1 patient), as shown in Table 3. In one case, one of
the two cerebral infarctions observed was extensive, whereas in another case, an infarction was noted in the left temporal lobe. The extensive cerebral infarction might be associated with multiple emboli due to cross-clamping or cannulation, and the temporal lobe cerebral infarction might be caused by cannulation. In the case with aortic dissection, rupture of the aortic dissection occurred at the site of aortic closure and the influence of cross-clamping or cannulation was not important.
Table 1 Patients characteristics Calc. n = 105
Non-calc. n = 102
p value 0.07
Age (years)
76.5 ± 4.4
77.0 ± 4.2
76.0 ± 4.5
Male (%/n)
39.1/81
40.0/42
38.2/39
0.9
Creatinine (mg/dl)
1.2 ± 1.4
1.3 ± 1.7
1.0 ± 0.9
0.2
Hypertension (%/n)
47.8/99
51.4/54
44.1/45
0.4
Diabetes (%/n)
10.1/21
16.2/17
3.9/4
0.007
Hemodialysis (%/n)
3.4/7
4.7/5
2.0/2
0.4
PAD (%/n)
10.1/21
16.2/17
3.9/4
0.007
Stroke (%/n)
5.3/11
6.7 %/7
3.9/4
0.5
IHD (%/n)
27.1/56
33.3/35
20.6/21
0.06
Maximum Ao PG (mmHg)
72.7 ± 26.0
71.3 ± 23.1
74.5 ± 29.7
0.5
Ao area (cm2)
0.6 ± 0.2
0.59 ± 0.20
0.58 ± 0.17
0.9
PAWP (mmHg)
14.2 ± 8.1
13.6 ± 8.2
14.9 ± 7.9
0.4
EF (%)
55.2 ± 13.0
56.4 ± 13.1
53.9 ± 12.7
0.2
NYHA class
2.0 ± 0.7
2.1 ± 0.7
2.0 ± 0.7
0.9
EuroSCORE (%)
24.4 ± 18.9
27.7 ± 20.3
21.0 ± 16.8
0.011
PAD peripheral arterial disease, IHD ischemic heart disease, PAWP pulmonary artery wedge pressure, EF ejection fraction
Distribution of calcification CT scan data were available for 207 patients who had isolated AVR; 105 had at least one segment of calcification. As shown in Table 4, 46 of the 105 patients with calcifications demonstrated calcifications in the distal portion of their aortas, 70 patients had calcification in the middle portions, 66 patients had calcification in the proximal portions, and 30 patients had calcification of their entire ascending aortas. Calcification in the distal zone (cannulation management) Distal aortic calcification was observed in 46 patients (Table 5). Of the 46 patients, conventional cannulations were performed in 26 patients; the cannulation site was moved to another favorable aortic site (9 patients), the femoral artery (7 patients), or to both the femoral and innominate arteries (4 patients). Axillary cannulation was not necessary in any of the patients. Of the 26 patients undergoing conventional cannulation, 2 died prior to hospital discharge (Table 3). None of the patients undergoing substitute cannulation died during hospitalization or suffered a stroke.
Table 2 Operative results
Operation (min)
239.0 ± 50.6
Calc. n = 105
Non-calc. n = 102
247.4 ± 54.2
230.5 ± 45.5
p value 0.04
CPB (min)
125.9 ± 30.5
130.5 ± 32.0
121.3 ± 28.3
0.06
Cross-clamping (min)
85.3 ± 24.8
89.1 ± 27.1
81.4 ± 21.3
0.06
Stroke (%/n)
2.4/5
1.9/2
2.9/3
0.40
DWI
1.4/3
2.9/3
0
Renal failure
4.3/9
4.8/5
3.9/4
[0.99
LOS Arrhythmia
5.8/12 2.9/6
5.7/6 2.9/3
5.9/6 2.9/3
[0.99 [0.99
Hospital death (%/n)
3.4/7
6.7/7
0
0.25
0.02
DWI deep wound infection, renal failure aggravation of the renal function (creatinine [2 mg/dl), LOS low output syndrome, arrhythmia ventricular fibrillation, ventricular flutter
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Gen Thorac Cardiovasc Surg Table 3 Hospital death Euro SCORE
Distribution
Cannulation
Cross-clamp
Incision
Cause of death
Case 1
53
Proximal ? middle ? distal
Conventional
Conventional
Substitute
Stroke
Case 2
53
Proximal
Conventional
Conventional
Conventional
Infection
Case 3
5
Proximal
Conventional
Conventional
Conventional
Vf
Case 4
18
Proximal ? middle ? distal
Conventional
Conventional
Conventional
NOMI
Case 5
20
Proximal ? middle
Conventional
Conventional
Conventional
stroke
Case 6
40
Middle
Conventional
Conventional
Conventional
Valve disfunction
Case 7
45
Middle
Conventional
Conventional
Conventional
DA
Vf ventricular fibrillation, NOMI non-occlusive mesenteric ischemia, DA aortic dissection
Table 4 Distribution of calcification n
Stroke (%/n)
Complication (%/n)
Mortality (%/n)
EuroSCORE
Distal
5
0/0
0/0
0/0
15.2
Middle
30
0/0
10.0/3
6.7/2
26.4
Proximal
23
0/0
13.0/3
8.7/2
29.1
Distal ? middle
4
0/0
0/0
0/0
33.4
Distal ? proximal
7
0/0
0/0
0/0
16.4
Middle ? proximal
6
16.7/1
16.7/1
16.7/1
11.9
30
3.3/1
3.3/6
6.6/2
34.9
Entire
Table 5 Strategy in the site of cannulation (n = 46) n Conventional substitute
26
Table 7 Strategy in the site of aortotomy (n = 66)
Stroke (%/n)
Mortality
n
3.8/1
7.7/2
Conventional site
Femoral artery
7
0
0
Conventional site ? EA
Femoral artery ? innominate artery
4
0
0
Substitute site
Right site of ascending aorta
4
0
0
Substitute site ? EA
Aortic arch
3
0
0
Proximal site of ascending aorta
2
0
0
Table 6 Strategy in the site of cross-clamping (n = 70)
Conventional
n
Stroke (%/n)
Mortality
63
3.2/2
7.9/5
Under direct vision with/without EA
5
0
0
Balloon
2
0
0
EA endarterectomy
Calcification in the middle zone (cross-clamping management) Mid-aorta calcification was present in 70 patients (Table 6). The majority of these patients underwent conventional cross-clamping. Cross-clamping was performed in the ascending aorta, taking particular care to orientate the clamp parallel to the calcification (63 patients). In 5
123
Stroke (%/n)
Mortality (%/n)
45
0
8.9/4
2
0
0
18 1
11.1/2
5.6/1
0
0
EA endarterectomy
patients, cross-clamping was performed under direct vision during HCA. This strategy included endarterectomy (2 patients). Balloon occlusion was performed in another 2 patients. Of the 63 patients undergoing conventional crossclamping, 5 died in-hospital (Table 3) and 2 suffered an early stroke. None of the patients undergoing substitute cross-clamping died in-hospital or suffered a stroke. Calcification in the proximal zone (aortotomy management) Table 7 describes the 66 patients with calcification at the aortotomy site. Conventional transverse aortotomy was performed in 47 patients (4 died in-hospital), with additional endarterectomy being performed in 2 patients. Substitute aortotomy was performed in 19 patients. Of the 19 patients, one patient died in-hospital and another survived an early stroke.
Gen Thorac Cardiovasc Surg
Discussion Intraoperative epiaortic ultrasound is a useful test for detecting atherosclerotic changes in the ascending aorta, intraoperatively [5]. However, surgeons are able to recognize this difficult situation only following the sternotomy. On the other hand, non-contrast CT scans identifies areas of aortic calcification. Computed tomographic scans can be performed before an elective sternotomy, and potential alterations of operative approach and any revised risk can then discussed with patients in the preoperative setting [6]. Computed tomographic scans provide reproducible and more accurate information regarding both the circumferential severity of the calcification and the proximal and distal extent of the calcification [5, 7]. Computed tomographic scans also help to determine the appropriate operative strategy, facilitating a more aggressive strategy for avoiding calcified areas and reducing the risk of stroke [8]. The presence of a calcified ascending aorta in AVR patients poses a serious dilemma for the surgeon because it may preclude safe cannulation and cross-clamping and create difficulties for aortotomy and suturing. Furthermore, the increased risks of cerebral embolization, aortic dissection, and mural laceration are serious problems [1, 2]. Therefore, several alternative methods, including apicoaortic conduit, deep HCA, aortic replacement, endoaortic balloon occlusion, and cross-clamping under direct vision, have been described for dealing with the calcified aorta. Nishi et al. described cross-clamping wherein particular attention is paid to orienting the clamp parallel to the calcification, based on the preoperative CT scan. They were able to routinely perform this procedure without increasing the risk of stroke or mortality [9]. In our experience, 2 patients who underwent conventional crossclamping, ensuring that the clamp was parallel to the calcification, suffered from cerebral infarction, suggesting that additional, meticulous studies may be necessary. Occluding the ascending aorta with a balloon catheter has also been proposed as a substitute for cross-clamping, on the assumption that it would be less traumatic and less prone to causing systemic emboli [10]. However, Bartolo et al. found that balloon occlusion was frequently ineffective; in 19.2 % of patients, the balloon had to be replaced by an ordinary cross-clamp because of incomplete occlusion, hindered exposure, or balloon rupture [11]. We have used this technique on a few cases but have found that the balloon can migrate, causing bleeding. Deep HCA, without cross-clamping, is possibly the simplest approach and can be performed with an acceptable mortality [12–14]. However, the associated time constraints may negatively affect the surgeon’s accuracy, increasing the risk of cerebral events in elderly patients [7]. Takami et al. reported a technique of cross-clamping during short-term, moderate
HCA after internal inspection or endarterectomy. In their study, they did not report any mortality or morbidity [15]. Similarly, in the current study, we did not observe associated strokes or mortality. Aortic replacement, before AVR, is a more radical approach. This technique avoids any aortic manipulation prior to deep HCA, cross-clamping the graft occurs following distal anastomosis; the AVR was carried out during the rewarming phase. The replacement of the diseased aorta eliminates the risk of aneurysmal formation and embolization. However, elderly patients requiring extensive procedures and prolonged periods on bypass have a substantially increased risk of mortality and morbidity [7, 16], but the results are acceptable [3, 7, 16, 17]. Aortic cannulation, when feasible, remains the preferred cannulation route. Moving the cannulation site away from the calcified sites may become a choice when the disease is well localized. These patients often have severe atherosclerosis of the descending aorta and peripheral vasculature and are at a high risk of retrograde embolism [7, 16]. If the femoral arteries are not suitable for cannulation because severe peripheral vascular disease or a major disease in the descending thoracic aorta preclude safe retrograde perfusion, the axillary artery is easily approached through a subclavian incision, if free from substantial disease [12, 18]. Aortic endarterectomy is useful in this setting. However, the potential for aneurysmal degeneration of the endarterectomized aorta remains unknown. In the present study, as well as in others described here, the mortality rates were low in patients undergoing the substitute techniques, supporting the safety of these techniques. Although the 8.3 % mortality rate observed in patients undergoing the conventional procedure was not negligible, it was lower than the expected 25.9 % estimated by the patient EuroSCOREs. Considering that the conventional procedure involves a less invasive approach, the conventional procedure appears to be sufficient for highrisk patients. Limitation This study was an observational clinical study. Although epiaortic echocardiography is now used routinely in the evaluation of patients having calcified aortas, in the current series such, patients were in the minority. In addition, the surgeon chose the operative techniques in a non-randomized fashion.
Conclusion Aortic valve replacement in patients with calcified ascending aortas is associated with increased operative
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Gen Thorac Cardiovasc Surg
morbidity and mortality. Although the conventional procedures provide reasonable results, according to the situation, the alternative techniques should be used properly. Conflict of interest interest.
All of the authors do not have the conflicts of
References 1. Buz S, Pasic M, Unbehaun A, Unbehaun A, Drews T, Dreysse S, Kukucka M, et al. Trans-apical aortic valve implantation in patients with severe calcification of the ascending aorta. Eur J Cardiothorac Surg. 2011;40:463–8. 2. Blauth CI, Cosgrove DM, Webb BW, Ratliff NB, Boylan M, Piedmonte MR, et al. Atheroembolism from the ascending aorta. An emerging problem in cardiac surgery. J Thorac Cardiovasc Surg. 1992;103:1104–11. 3. Gillinov AM, Lytle BW, Hoang V, Cosgrove DM, Banbury MK, McCarthy PM, et al. The atherosclerotic aorta at aortic valve replacement: surgical strategies and results. J Thorac Cardiovasc Surg. 2000;120:957–65. 4. Zingone B, Rauber E, Gatti G, Pappalardo A, Benussi B, Forti G, et al. Diagnosis and management of severe atherosclerosis of the ascending aorta and aortic arch during cardiac surgery; focus on aortic replacement. Eur J Cardiothorac Surg. 2007;31:990–7. 5. Zingone B, Rauber E, Gatti G, Pappalardo A, Benussi B, Dreas L, et al. The impact of epiaortic ultrasonographic scanning on the risk of perioperative stroke. Eur J Cardiothorac Surg. 2006; 29:720–8. 6. Nishi H, Mitsuno M, Tanaka H, Ryomoto M, Fukui S, Miyamoto Y. Who needs preoperative routine chest computed tomography for prevention of stroke in cardiac surgery? Interact Cardiovasc Thorac Surg. 2010;11:30–3. 7. Aranki SF, Nathan M, Shekar P, Couper G, Rizzo R, Cohn LH. Hypothermic circulatory arrest enables aortic valve replacement in patients with unclampable aorta. Ann Thorac Surg. 2005; 80:1679–87.
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8. Lee R, Matsutani N, Polimenakos AC, Levers LC, Lee ML, Johnson RG. Preoperative noncontrast chest computed tomography identifies potential aortic emboli. Ann Thorac Surg. 2007;84:38–42. 9. 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. 10. Erath HG, Stoney WS. Balloon catheter occlusion of the ascending aorta. Ann Torac Surg. 1983;35:560–1. 11. Kayatta MO, Ahmed S, Hammel JA, Femandez F, Pickens A, Miller D, et al. Surgical biopsy of suspected interstitial lung disease is superior to radiographic diagnosis. Ann Thorac Surg. 2013;96:399–401. 12. Byrne JG, Aranki SF, Cohn LH. Aortic valve operations under deep hypothermic circulatory arrest for the porcelain aorta: ‘‘NoTouch’’ technique. Ann Thorac Surg. 1998;65:1313–5. 13. Jacobowitz IJ, Rose DM, Shevede K, Cunningham JN. Use of profound hypothermia and circulatory arrest for the calcified aorta. Chest. 1984;85:288–9. 14. Coselli JS, Crowford ES. Aortic valve replacement in the patient with extensive calcification of the ascending aorta (the porcelain aorta). J Thorac Cardiovasc Surg. 1986;91:184–7. 15. Takami Y, Tajima K, Terazawa S, Okada N, Fujii K, Sakai Y. Safer aortic crossclamping during short-term moderate hypothermic circulatory arrest for cardiac surgery in patients with a bad ascending aorta. J Thorac Cardiovasc Surg. 2009;137:875–80. 16. 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. 17. Zingone B, Gatti G, Spina A, Rauber E, Dreas L, Forti G, et al. Current role and outcomes of ascending aortic replacement for severe nonaneurysmal aortic atherosclerosis. Ann Thorac Surg. 2010;89:429–34. 18. Svensson LG, Blackstone EH, Rajeswaran J, Sabik JF, Lytle BW, McCarthy PM, et al. Does the arterial cannulation site for circulatory arrest influence stroke risk? Ann Thorac Surg. 2004;78: 1274–84.
