Conventional Valve Replacement Research Articles

Unusual thrombus formation in the aorta after apicoaortic conduit for severe aortic stenosis

Conventional valve replacement for aortic valve stenosis has significant operative risks in patients with dense, circumferential calcification of the ascending aorta. The apicoaortic conduit (AAC) is one of the alternative methods to eliminate the aortic manipulation. Several reports have demonstrated that a newly constructed double-outlet left ventricle maintains normally distributed blood flow throughout the systemic circulation without any deleterious physiologic effects. 1,2 However, we encountered the case of a patient who had unanticipated thrombus formation in the aortic arch that might have resulted from fractionation of the cardiac output and stagnation of the blood flow after construction of the AAC. Clinical Summary A 72-year-old woman with a history of diabetes mellitus and chronic renal insufficiency requiring hemodialysis experienced progressive dyspnea on exertion. Echocardiography demonstrated severe aortic stenosis caused by a calcified valve. Cardiac catheterization demonstrated a pressure gradient of 58 mm Hg across the aortic valve, a cardiac index of 3.5 L · min 1 ·m 2 , and 90% stenosis of the proximal right coronary artery. Computed tomography showed severe circumferential aortic calcification of the whole aorta, including the aortic root. To preclude the aortic valve procedure through a median sternotomy, we inserted the AAC through the left thoracotomy. The thoracic cavity was entered through the sixth intercostal space, and cardiopulmonary bypass was initiated with distal descending aortic cannulation and right femoral venous drainage. The patient was kept normothermic, and a 20-mm Hemashield graft (Meadox, Hemashield; Boston Scientific, Boston, Mass) was sewn to the descending aorta during side clamping. Continuous infusion of -blocker was started, and the heart rate was decreased to around 30 beats/min. In a head-down position, the left ventricular apex was enucleated with a 20-mm coring knife. The valved conduit incorporating a 23-mm stentless valve (Edwards Prima Plus; Stentless Bioprosthesis, Inc, Irvine, Calif) and a 20-mm Hemashield graft was anastomosed with the apical hole. The 2 parts of the conduit were then anastomosed. A saphenous vein graft placed from the coronary orifice of the stentless valve was grafted to the right coronary artery concomitantly. The postoperative course was uncomplicated, and the patient had improvement of symptoms. Computed tomography at 1 month after the operation demonstrated unobstructed conduit (Figure 1) and unexpected thrombus formation, possibly caused by stagnation of blood flow in the aortic arch (Figure 2). Administration of sodium warfarin was initiated immediately, and no thromboembolic events have been observed. Discussion Recent modifications of the technique and innovation of the technology has made it more feasible to accomplish the AAC for various complex lesions of the left ventricular outflow tract not easily amenable to other techniques. 3,4 In our case creation of an AAC combined with coronary revascularization was successfully performed with a pharmacologically controlled beating heart, which is a new and lessinvasive procedure even with the support of cardiopulmonary bypass. Furthermore, the use of a stentless bioprosthesis enabled us to obtain a larger valve orifice and to avoid anticoagulation. The patient was freed from heart failure symptoms, and postoperative computed to

Echocardiographic and hemodynamic characteristics of reconstructed bicuspid aortic valves at rest and exercise

Repair of diseased bicuspid aortic valves has gained increasing interest as an alternative to conventional valve replacement. Hemodynamic data at exercise have not been reported before. The aim of this study was to investigate the clinical and echocardiographic status of patients after bicuspid aortic valve repair at rest and exercise. Between 03/94 and 09/02 a reconstruction of an incompetent bicuspid aortic valve was performed in 25 patients (mean age 35+/-12.1 years, group A, mean insufficiency 2.8 preoperatively). Patients were investigated clinically and echocardiographically after 2.1+/-2.4 (0.1-8.9) years at rest and exercise and compared to 20 controls (group B). Clinical followup was complete. There were no deaths, reoperations, thromboembolic or bleeding complications. At last examination 21 patients were in NYHA class I, n=4 in NYHA class II and mean aortic valve insufficiency (AI) was 1.0 with one patient having an AI>II degrees. Maximum and mean pressure gradient (dPmax/mean) across the aortic valve at rest were 14+/-5.5/7+/-2.6 mmHg for patients of group A and 7+/-2.5/3.6+/-1.1 mmHg in group B. Mean AVA at rest was 2.6+/-0.8 (group A) vs 2.9+/-0.6 cm(2) (group B, p=0.025), valvular resistance 13.4+/-4.8 (group A) vs 13.6+/-2.9 dyn x s x cm(-5) (group B, p>0.05). All individuals were stressed up to 100 W (dPmax/mean 21+/-6.8/11+/-3.6, group A vs 11+/-2.9/6+/-1.3 mmHg, group B). 56% of group A and 85% of group B could be stressed up to 175 W with dPmax/mean 24.5+/-8.3/12+/-4.2 and 16+/-3.6/8+/-1.4 mmHg, respectively (p<0. 01). Heart rate and blood pressure behavior were comparable. Left ventricular mass regression (preoperatively 369.3+/-76.4 vs 277.3+/-80.7 g at last examination, p<0.01) was significant in group A but did not reach normal values (group B, 227.8+/-71.1; p<0.01). Bicuspid aortic valve reconstruction reduces left ventricular volume load significantly. Although residual mild subclinical obstruction and incompetence were observed, the behavior of hemodynamics at exercise was comparable to controls. The clinical relevance of these findings in long term follow-up has to be evaluated.

A novel repair for patients with atrioventricular septal defect requiring reoperation for left atrioventricular valve regurgitation.

Left atrioventricular valve regurgitation (LAVVR) is the most frequent indication for reoperation following atrioventricular septal defect (AVSD) repair. We estimate from our experience that within 10 years of initial repair, 14% of patients undergoing repair of atrioventricular septal defect (AVSD) require reoperation for this complication. We have developed a novel leaflet augmentation technique for LAVVR which may avoid failure of conventional repair and/or the need for valve replacement. The novel technique consists of insertion of a glutaraldehyde-treated autologous pericardial patch to augment the bridging leaflets of the atrioventricular valve. We describe the outcome of eight patients in whom this technique was used and compared them to 68 other patients with AVSD undergoing reoperation for LAVVR by either conventional repair (n=54) or valve replacement (n=14). There were no early deaths or major complications following patch repair. The mean follow-up is 2.3 years (range 1-8.5 years) during which there were no late deaths. Two patients underwent reintervention at 3.5 and 5 years after patch repair for LAVVR and were successfully rerepaired. Mild residual LAVVR was seen at last echocardiography in six patients and mild to moderate in two. These results compare favorably with the 68 patients who underwent conventional surgery. The 3-year freedom from reoperation was 86% for both repair groups. Dysplastic valve tissue appears to be a major risk factor for failure of conventional repair or for valve replacement. Failure of conventional valve repair led to valve replacement in six of seven patients. For patients with late LAVVR after AVSD repair, pericardial leaflet augmentation is durable and may avoid failure of conventional repair or valve replacement in patients with dysplastic valves.

Early Clinical Results After Stentless Mitral Valve Implantation and Comparison With Conventional Valve Repair or Replacement

Background —A new quadricusp stentless mitral bioprosthetic valve (QMV) is evaluated and compared with current standards. Methods and Results —Since August 1997, 67 patients were prospectively evaluated: 23 patients received a QMV, 23 had mitral valve repair (MVR), and 21 received conventional mitral valve replacement (MVP). Patient age was 69±8, 64±10, and 62±9 years for QMV, MVR, and MVP treatment, respectively. The underlying pathology was mitral stenosis, incompetence, and mixed disease in a corresponding 8, 9, and 6 patients for QMV, 1, 22, and 0 patients for MVR, and 2, 12, and 7 patients for MVP. The papillary muscles were sufficient in all QMV cases to suspend the valve. Cross-clamp time was 59±19 minutes for QMV implantation. In-hospital mortality for QMV, MVR, and MVP was 1, 0, and 0 patients, respectively, and thoracotomy had to be performed again in 1, 1, and 2 patients, respectively (these outcomes were not valve related). At baseline transthoracic echocardiography, respective maximum flow velocities were 1.6, 1.4, and 1.7 m/s, and valve orifice area was 2.6, 3.5, and 3.4 cm 2 . Mild transvalvular reflux was seen in 8, 7, and 2 patients; moderate reflux, in 1, 1, and 1 patients. Left ventricular ejection fraction was 52%, 54%, and 51% in the respective treatment groups. At follow-up, hemodynamic parameters had further improved in all groups. Conclusions —One year after clinical implantation, the QMV appears to function well and has no additional risks compared with MVR or MVP. The subvalvular apparatus is preserved by suspending the QMV at the papillary muscles; this arrangement is hemodynamically advantageous. Echocardiography reveals an excellent valve performance that resembles native mitral valve morphology and hemodynamic function. The QMV is a promising alternative for biological mitral valve replacement.

Aortic root replacement with a pulmonary autograft in young adults: medium-term results in 70 patients

Background. Pulmonary autograft aortic valve replacement has been introduced in our institution in selected adult patients in light of the known disadvantages and limitations of conventional prosthetic valves. Methods. We prospectively evaluated the use of the pulmonary autograft in a series of 70 young adults (31.2 ± 8.7 years, range 16 to 49 years) operated on from March 1992 to April 1997 with aortic root replacement only. Results. There were no in-hospital deaths and two noncardiac-related late deaths during follow-up of up to 62 months (mean 33 months). Thromboembolic complications were not observed. One patient required reoperation for infective endocarditis 4.3 years after surgery. Discharge echo-Doppler studies showed normal autograft and allograft valve function. Serial echo-Doppler studies showed no significant progression of aortic insufficiency and no dilatation of the autograft. A severe stenosis of the pulmonary allograft developed in 1 patient. Conclusion. Aortic root replacement with a pulmonary autograft, although more complex than conventional prosthetic valve replacement, is a safe, effective, and reproducible procedure in properly selected adult patients. Long-term results remain to be evaluated.

Left ventricular dimension changes after chordal preservation in mitral valve replacement

Clinical and experimental evidence regarding the benefits of preserving the subvalvular apparatus during mitral valve replacement has been debated. Reductions in the left ventricular end-diastolic dimensions have been shown, by echocardiography, to correlate well with the levels of clinical improvement following successful valve surgery. Seventynine patients underwent mitral valve replacement for mitral stenosis, regurgitation or both. In 42 patients, a conventional valve replacement was performed, excising both leaflets along with their chordae. In the remaining 37, a modified technique was used preserving the posterior leaflet and chordae. The two groups did not differ significantly in their demographic profiles, clinical classes and pathology. Echocardiographic assessment of left atrial and left ventricular dimensions was done preoperatively and prior to discharge. Median left atrial dimensions decreased in both groups. Postoperatively, the left ventricular end-diastolic and end-systolic parameters remained either the same or showed an increase in the conventional group. Patients in the modified group, however registered a decrease in left ventricular dimensions. Such changes further supported the clinical evidence suggesting benefits of preserving the chordae tendinae in mitral valve replacement.

Surgical bypass of the systemic atrioventricular valve in children by means of a valved conduit

The surgical approach to relief of mitral stenosis in children is still a controversial problem. We describe our experience with four severely symptomatic children in whom a valved conduit from the left atrium to the left ventricle was successfully used to bypass a hypoplastic systemic atrioventricular valve. A left atrial-left ventricular extracardiac conduit was implanted in these patients with a hypoplastic mitral anulus and an adequate left ventricular chamber. There were no early or late deaths. Postoperative cardiac catheterization performed in all patients 1 month after the operation showed reduced size of the left atrium, a reduction of the left atrial-left ventricular gradient from a mean of 14 mm Hg to a mean of 5 mm Hg, and an increase of the left atrial outlet from a mean diameter of 10.7 mm to 28.7 mm (including the diameter of the native mitral valve plus the internal diameter of the valved conduit). The application of this unconventional operation in children with congenital or acquired stenosis of the systemic atrioventricular valve should be considered when the mitral valve obstruction cannot be relieved by conventional valve repair or replacement. Furthermore, the left atrial-left ventricular conduit does not preclude future alternative surgical options.