Valve Placement in the Ventricular Apex for Complicated Left Ventricular Outflow Obstruction Gordon F. Murray, M.D. ABSTRACT Successful correctionof severe valvular calcific aortic stenosis is described in which a stented porcine aortic heterograft was placed in the ventricular apex. Creation of a double outlet is a valid alternative approach to relieve left ventricular hypertension, and indication for such a procedure may be encountered unexpectedly. Intramyocardial placement of a durable tissue valve provides a simple and effective option for the cardiac surgeon.
Predictable relief of extreme obstruction to left ventricular outflow by interposition of a valvebearing conduit between the ventricular apex and the aorta has recently been demonstrated [2, 5, 6, 8, 93. A compelling indication for use of the procedure is congenital hypoplasia of the left ventricular outflow tract, which cannot be relieved by conventional techniques [5, 61. Acquired aortic stenosis with severe annular narrowing or aortic calcification, or both, or a difficult prosthetic valve replacement are additional indications for such an operative approach [8], and may be encountered unexpectedly. This report describes successful correction of severe calcific aortic stenosis by placement of a stented porcine aortic heterograft* in the ventricular apex. Intramyocardial placement of the heterograft with external support utilizes a durable tissue valve and eliminates the requirement for a specially designed rigid ventricular insert. A 65-year-old woman was admitted to North Carolina Memorial Hospital for the first time in October, 1965, for evaluation of a heart murmur and vague symptoms of easy fatigability and dyspnea. Cardiac catheterization demonstrated aortic stenosis with a valve area of 0.9 cm'. Operative correction was recommended, but reFrom the Division of Cardiothoracic Surgery, University of North Carolina School of Medicine, Clinical Sciences Building 229-H, Chapel Hill, NC 27514. Accepted for publication Sept 23, 1977. *Hancock Laboratories, Inc, Anaheim, CA. 368
fused by the patient. Her clinical status remained stable until November, 1976, when progressive symptoms of orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, and dyspnea on exertion confined her to bed and necessitated hospitalization elsewhere. Despite intractable congestive heart failure with severe dyspnea and swelling of the ankles and abdomen, the patient continued to refuse operation until February 16,1977, when consent for cardiac catheterization was obtained and the patient was transferred in extremis to North Carolina Memorial Hospital. Shortly after the patient's admission, right and left heart catheterization revealed severe calcific aortic stenosis and left ventricular dysfunction. Pulmonary artery pressure was 65/35mm Hg and capillary wedge pressure was 33 mm Hg. The left ventricular pressure was 20044 mm Hg with a low mean systemic pressure of 70 mm Hg. Aortic valve area was calculated to be 0.2 cmz. The left ventricular ejection fraction was 0.2 with a cardiac index of 1.2 liters per minute per square meter of body surface area. On March 18, exploration was carried out through a median sternotomy . Extensive calcification of the aortic root and ascending aorta was noted, and valve replacement in the subcoronary position was not considered feasible. Therefore, the midline incision was extended into the abdomen and a preclotted 25-mm woven Dacron graft was sewn end-to-side to the supraceliac abdominal aorta. Cardiopulmonary bypass was then instituted, and a measured core of ventricular muscle equal to a No. 23 porcine aortic valve sizer was removed at the apex. A No. 23 porcine aortic valve heterograft was then secured within the myocardium with interrupted mattress sutures reinforced with Teflon pledgets (Fig 1A). The Dacron graft was passed through a small aperture created in the diaphragm and was sutured over the tissue valve to establish ventriculoaortic continuity (Fig 1B). A running suture included the Dacron graft, the sewing ring of
0003-497517810025-0416$1.00 @ 1978 by Gordon F. Murray
369
Case Report: Murray: Valve Placement in the Apex Position
Fig I. (A)A durable porcine aortic valve heterograft is secured at the apex of the left ventricle. ( B ) Ventriculoaortic continuity is established with a Dacron graft. (C) Coronary revascularization may be accomplished with a reversed saphenous vein graft.
the valve, and the Teflon pledgets on the epicardial surface. There was no difficulty with hemostasis, and cardiopulmonary bypass was readily discontinued. Intraoperative left ventricular pressure was 100/8 mm Hg, and simultaneous systemic pressure measured at the radial artery was 110/70mm Hg. Hence there was no remaining pressure gradient across the aortic valve. The patient's immediate postoperative course was tenuous and complicated by her extreme debility. She required tracheal intubation on several occasions for removal of secretions. However, one month after the procedure she was considerably improved and able to return to the care of her family. Symptoms and signs of congestive heart failure were easily controlled with digoxin, 0.125 mg each day, and mild diuresis.
On June 3,1977, the patient returned to the clinic free from edema and pleural effusions and without orthopnea or dyspnea on exertion (Fig 2). Auscultation revealed a soft apical ejection murmur and a clear sound of prosthetic valve closure. No diastolic murmur was heard at the apex. Four months after operation the patient was able to do housework without symptoms and had an excellent appetite. Comment The pioneering clinical efforts of Templeton [ll] and Bernhard and associates [21 demonstrated technical application of a valve-bearing conduit interposed between the apex of the left ventricle and the aorta to relieve left ventricular hypertension. Of late, the group at the Texas Heart Institute [8]has established that effective, reproducible relief of extreme left ventricular outflow tract obstruction may be achieved by this approach. Apicoaortic valved conduits were initially inserted for relief of obstruction at the annular and
370 The Annals of Thoracic Surgery Vol 25 No 4 April 1978
A
B
Fig2. (A) Postoperativechest roentgenogram on June3, 1977, shows heterograft valve in place at the apex of the left ventricle. ( B ) Extensive calcification of the aortic root is seen on lateral projection.
cogent with valve placement at the apex in the adult with acquired life-threatening aortic obstruction. Extensive experience has shown the stented porcine aortic heterograft to be a remarkably durable tissue valve. Stinson and coworkers [lo] reported that 98% of 167 patients who underwent aortic valve replacement were free of porcine aortic heterograft valve dysfunction at an interval of three years, and no intrinsic pathological involvement of the heterograft tissue was documented. In contrast, the unstented porcine valve in a Dacron graft is not well supported, and the commercially available Hancock prosthesis was designed for use in the lowpressure pulmonary circulation. Bernhard [l] reported the development of insufficiency in a heterograft conduit valve 18 months after operation in his first patient, and has suggested the possibility of improving external support of the valve commissures. Direct placement in the ventricular apex of a tissue valve with recognized durability, as described here, would seem a simple and readily available alternative. Optimal diversion of left ventricular flow with a valve-bearing conduit is thought to require a specially designed rigid left ventricular insert [5, 8, 91. In their initial experience with 4 patients,
supravalvular areas [2, 81. Subsequently, Dembitsky and Weldon [5] and Reder and associates [91 constructed double-outlet left ventricles for diffuse muscular subaortic stenosis. The application of left ventricular and biventricular extracardiac conduits in four types of complex congenital anomalies has recently been discussed by McGoon [6]. The advantage of an extracardiac valved conduit is immediately apparent when relief of complicated left ventricular obstruction is required in the child and young adult. It is reasonable to assume that all available prosthetic or tissue valves will eventually require replacement; with this in mind, Norman and associates [8] have stressed the importance of placing the valve beneath the diaphragm to avoid thoracic reentry. Whereas an extracardiac conduit has advantages over plastic reconstruction of the aortic root because it allows valve replacement in the subcoronary position in children, this concept is less
371
Case Report: Murray: Valve Placement in the Apex Position
Cooley and associates [4, 81 sutured the deformable Dacron conduit directly to the left ventricle. Although satisfactory management was achieved, postoperative angiograms showed compression of the grafts by the myocardium during midsystole, and a special rigid insert was subsequently developed. The desirability of a rigid inlet tube for the ventricle is also suggested by the laboratory work of Brown and co-workers [3], who demonstrated eventual muscular occlusion of an apical prosthesis that did not reach the endocardial surface. To date, left ventricular apical insert prostheses of methyl methacrylate [ll], stainless steel [2,5], carbon [8], and polyurethane [9] have been reported in clinical use. As demonstrated in this report, when severe aortic calcification or other extreme difficulty is encountered unexpectedly, a stented porcine aortic heterograft also may serve as the ventricular insert (see Fig 1A). The stellite ring-reinforced annulus of the stent is secured at the level of the ventricular endocardial surface to provide a smooth inflow orifice. The flexible polypropylene Dacroncovered stent is encompassed by the Dacron graft to discourage muscular encroachment on the central-flow prosthesis (see Fig 1B). Thus, intramyocardial placement of the valve eliminates the need for a specially designed apical insert and provides a simple and effective option for the surgeon. A concurrent indication for coronary revascularization can be anticipated in the adult patient selected for a left ventricle-aorta conduit. Norman and associates [8] have, in fact, performed double reversed saphenous vein coronary bypass grafts from a composite conduit in a patient with calcific aortic stenosis and extensive calcification of the ascending aorta. The autologous saphenous vein grafts were anastomosed to the conduit distal to the porcine valve in the abdomen and passed retrograde through the diaphragm. Performing the distal conduit aortic anastomosis in the left chest [9] would also re-
quire a long and tortuous route for vein grafts to the appropriate coronary arteries. The current technique of intramyocardial placement of the valve would allow origin of a vein graft at the apex within the pericardium (see Fig 1C). The short, protected course of the saphenous graft should simplify the revascularization procedure and lessen the opportunity for kinking o r compression of the vessel.
References 1. Bernhard WF: Discussion of Dembitsky and Wel-
don [5] 2. Bernhard WF, Poirier V, LaFarge CG: Relief of congenital obstruction to left ventricular outflow with a ventricular-aortic prosthesis. J Thorac Cardiovasc Surg 69:223, 1975 3. Brown JW,Myerowitz PD, Cann MS, et al: Apical-aortic anastomosis: a method for relief of diffuse left ventricular outflow obstruction. Surg Forum 25:147, 1974 4. Cooley DA, Norman JC, Mullins CE, et al: Left ventricle to abdominal aorta conduits for relief of aortic stenosis. Bull Texas Heart Inst 2:376, 1975 5. Dembitsky WP, Weldon CS: Clinical experience with a valve-bearing conduit to construct a second left ventricular outflow tract in cases of unresectable intraventricular obstruction. Ann Surg 184:317, 1976 6. McGoon DC: Left ventricular and biventricular extra-cardiac conduits. J Thorac Cardiovasc Surg 72:7, 1976 7. Norman JC: Discussion of Dembitsky and Weldon [51 8. Norman JC, Nihill MR, Cooley DA: Creation of double-outlet left ventricles for left ventricular outflow obstructions: initial clinical results in six patients. Trans Am SOC Artif Intern Organs 22:332, 1976 9. Reder RF, Dimich I, Steinfeld L, et al: Left ventricle to aorta valved conduit for relief of diffuse left ventricular outflow tract obstruction. Am J Cardiol 39:1068, 1977 10. Stinson EB, Griepp RB, Oyer PE, et al: Long-term experience with porcine aortic valve xenografts. J Thorac Cardiovasc Surg 73:54, 1977 11. Templeton JY 111: Cited by Reder et a1 [9]
Predictable relief of extreme obstruction to left ventricular outflow by interposition of a valvebearing conduit between the ventricular apex and the aorta has recently been demonstrated [2, 5, 6, 8, 93. A compelling indication for use of the procedure is congenital hypoplasia of the left ventricular outflow tract, which cannot be relieved by conventional techniques [5, 61. Acquired aortic stenosis with severe annular narrowing or aortic calcification, or both, or a difficult prosthetic valve replacement are additional indications for such an operative approach [8], and may be encountered unexpectedly. This report describes successful correction of severe calcific aortic stenosis by placement of a stented porcine aortic heterograft* in the ventricular apex. Intramyocardial placement of the heterograft with external support utilizes a durable tissue valve and eliminates the requirement for a specially designed rigid ventricular insert. A 65-year-old woman was admitted to North Carolina Memorial Hospital for the first time in October, 1965, for evaluation of a heart murmur and vague symptoms of easy fatigability and dyspnea. Cardiac catheterization demonstrated aortic stenosis with a valve area of 0.9 cm'. Operative correction was recommended, but reFrom the Division of Cardiothoracic Surgery, University of North Carolina School of Medicine, Clinical Sciences Building 229-H, Chapel Hill, NC 27514. Accepted for publication Sept 23, 1977. *Hancock Laboratories, Inc, Anaheim, CA. 368
fused by the patient. Her clinical status remained stable until November, 1976, when progressive symptoms of orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, and dyspnea on exertion confined her to bed and necessitated hospitalization elsewhere. Despite intractable congestive heart failure with severe dyspnea and swelling of the ankles and abdomen, the patient continued to refuse operation until February 16,1977, when consent for cardiac catheterization was obtained and the patient was transferred in extremis to North Carolina Memorial Hospital. Shortly after the patient's admission, right and left heart catheterization revealed severe calcific aortic stenosis and left ventricular dysfunction. Pulmonary artery pressure was 65/35mm Hg and capillary wedge pressure was 33 mm Hg. The left ventricular pressure was 20044 mm Hg with a low mean systemic pressure of 70 mm Hg. Aortic valve area was calculated to be 0.2 cmz. The left ventricular ejection fraction was 0.2 with a cardiac index of 1.2 liters per minute per square meter of body surface area. On March 18, exploration was carried out through a median sternotomy . Extensive calcification of the aortic root and ascending aorta was noted, and valve replacement in the subcoronary position was not considered feasible. Therefore, the midline incision was extended into the abdomen and a preclotted 25-mm woven Dacron graft was sewn end-to-side to the supraceliac abdominal aorta. Cardiopulmonary bypass was then instituted, and a measured core of ventricular muscle equal to a No. 23 porcine aortic valve sizer was removed at the apex. A No. 23 porcine aortic valve heterograft was then secured within the myocardium with interrupted mattress sutures reinforced with Teflon pledgets (Fig 1A). The Dacron graft was passed through a small aperture created in the diaphragm and was sutured over the tissue valve to establish ventriculoaortic continuity (Fig 1B). A running suture included the Dacron graft, the sewing ring of
0003-497517810025-0416$1.00 @ 1978 by Gordon F. Murray
369
Case Report: Murray: Valve Placement in the Apex Position
Fig I. (A)A durable porcine aortic valve heterograft is secured at the apex of the left ventricle. ( B ) Ventriculoaortic continuity is established with a Dacron graft. (C) Coronary revascularization may be accomplished with a reversed saphenous vein graft.
the valve, and the Teflon pledgets on the epicardial surface. There was no difficulty with hemostasis, and cardiopulmonary bypass was readily discontinued. Intraoperative left ventricular pressure was 100/8 mm Hg, and simultaneous systemic pressure measured at the radial artery was 110/70mm Hg. Hence there was no remaining pressure gradient across the aortic valve. The patient's immediate postoperative course was tenuous and complicated by her extreme debility. She required tracheal intubation on several occasions for removal of secretions. However, one month after the procedure she was considerably improved and able to return to the care of her family. Symptoms and signs of congestive heart failure were easily controlled with digoxin, 0.125 mg each day, and mild diuresis.
On June 3,1977, the patient returned to the clinic free from edema and pleural effusions and without orthopnea or dyspnea on exertion (Fig 2). Auscultation revealed a soft apical ejection murmur and a clear sound of prosthetic valve closure. No diastolic murmur was heard at the apex. Four months after operation the patient was able to do housework without symptoms and had an excellent appetite. Comment The pioneering clinical efforts of Templeton [ll] and Bernhard and associates [21 demonstrated technical application of a valve-bearing conduit interposed between the apex of the left ventricle and the aorta to relieve left ventricular hypertension. Of late, the group at the Texas Heart Institute [8]has established that effective, reproducible relief of extreme left ventricular outflow tract obstruction may be achieved by this approach. Apicoaortic valved conduits were initially inserted for relief of obstruction at the annular and
370 The Annals of Thoracic Surgery Vol 25 No 4 April 1978
A
B
Fig2. (A) Postoperativechest roentgenogram on June3, 1977, shows heterograft valve in place at the apex of the left ventricle. ( B ) Extensive calcification of the aortic root is seen on lateral projection.
cogent with valve placement at the apex in the adult with acquired life-threatening aortic obstruction. Extensive experience has shown the stented porcine aortic heterograft to be a remarkably durable tissue valve. Stinson and coworkers [lo] reported that 98% of 167 patients who underwent aortic valve replacement were free of porcine aortic heterograft valve dysfunction at an interval of three years, and no intrinsic pathological involvement of the heterograft tissue was documented. In contrast, the unstented porcine valve in a Dacron graft is not well supported, and the commercially available Hancock prosthesis was designed for use in the lowpressure pulmonary circulation. Bernhard [l] reported the development of insufficiency in a heterograft conduit valve 18 months after operation in his first patient, and has suggested the possibility of improving external support of the valve commissures. Direct placement in the ventricular apex of a tissue valve with recognized durability, as described here, would seem a simple and readily available alternative. Optimal diversion of left ventricular flow with a valve-bearing conduit is thought to require a specially designed rigid left ventricular insert [5, 8, 91. In their initial experience with 4 patients,
supravalvular areas [2, 81. Subsequently, Dembitsky and Weldon [5] and Reder and associates [91 constructed double-outlet left ventricles for diffuse muscular subaortic stenosis. The application of left ventricular and biventricular extracardiac conduits in four types of complex congenital anomalies has recently been discussed by McGoon [6]. The advantage of an extracardiac valved conduit is immediately apparent when relief of complicated left ventricular obstruction is required in the child and young adult. It is reasonable to assume that all available prosthetic or tissue valves will eventually require replacement; with this in mind, Norman and associates [8] have stressed the importance of placing the valve beneath the diaphragm to avoid thoracic reentry. Whereas an extracardiac conduit has advantages over plastic reconstruction of the aortic root because it allows valve replacement in the subcoronary position in children, this concept is less
371
Case Report: Murray: Valve Placement in the Apex Position
Cooley and associates [4, 81 sutured the deformable Dacron conduit directly to the left ventricle. Although satisfactory management was achieved, postoperative angiograms showed compression of the grafts by the myocardium during midsystole, and a special rigid insert was subsequently developed. The desirability of a rigid inlet tube for the ventricle is also suggested by the laboratory work of Brown and co-workers [3], who demonstrated eventual muscular occlusion of an apical prosthesis that did not reach the endocardial surface. To date, left ventricular apical insert prostheses of methyl methacrylate [ll], stainless steel [2,5], carbon [8], and polyurethane [9] have been reported in clinical use. As demonstrated in this report, when severe aortic calcification or other extreme difficulty is encountered unexpectedly, a stented porcine aortic heterograft also may serve as the ventricular insert (see Fig 1A). The stellite ring-reinforced annulus of the stent is secured at the level of the ventricular endocardial surface to provide a smooth inflow orifice. The flexible polypropylene Dacroncovered stent is encompassed by the Dacron graft to discourage muscular encroachment on the central-flow prosthesis (see Fig 1B). Thus, intramyocardial placement of the valve eliminates the need for a specially designed apical insert and provides a simple and effective option for the surgeon. A concurrent indication for coronary revascularization can be anticipated in the adult patient selected for a left ventricle-aorta conduit. Norman and associates [8] have, in fact, performed double reversed saphenous vein coronary bypass grafts from a composite conduit in a patient with calcific aortic stenosis and extensive calcification of the ascending aorta. The autologous saphenous vein grafts were anastomosed to the conduit distal to the porcine valve in the abdomen and passed retrograde through the diaphragm. Performing the distal conduit aortic anastomosis in the left chest [9] would also re-
quire a long and tortuous route for vein grafts to the appropriate coronary arteries. The current technique of intramyocardial placement of the valve would allow origin of a vein graft at the apex within the pericardium (see Fig 1C). The short, protected course of the saphenous graft should simplify the revascularization procedure and lessen the opportunity for kinking o r compression of the vessel.
References 1. Bernhard WF: Discussion of Dembitsky and Wel-
don [5] 2. Bernhard WF, Poirier V, LaFarge CG: Relief of congenital obstruction to left ventricular outflow with a ventricular-aortic prosthesis. J Thorac Cardiovasc Surg 69:223, 1975 3. Brown JW,Myerowitz PD, Cann MS, et al: Apical-aortic anastomosis: a method for relief of diffuse left ventricular outflow obstruction. Surg Forum 25:147, 1974 4. Cooley DA, Norman JC, Mullins CE, et al: Left ventricle to abdominal aorta conduits for relief of aortic stenosis. Bull Texas Heart Inst 2:376, 1975 5. Dembitsky WP, Weldon CS: Clinical experience with a valve-bearing conduit to construct a second left ventricular outflow tract in cases of unresectable intraventricular obstruction. Ann Surg 184:317, 1976 6. McGoon DC: Left ventricular and biventricular extra-cardiac conduits. J Thorac Cardiovasc Surg 72:7, 1976 7. Norman JC: Discussion of Dembitsky and Weldon [51 8. Norman JC, Nihill MR, Cooley DA: Creation of double-outlet left ventricles for left ventricular outflow obstructions: initial clinical results in six patients. Trans Am SOC Artif Intern Organs 22:332, 1976 9. Reder RF, Dimich I, Steinfeld L, et al: Left ventricle to aorta valved conduit for relief of diffuse left ventricular outflow tract obstruction. Am J Cardiol 39:1068, 1977 10. Stinson EB, Griepp RB, Oyer PE, et al: Long-term experience with porcine aortic valve xenografts. J Thorac Cardiovasc Surg 73:54, 1977 11. Templeton JY 111: Cited by Reder et a1 [9]
