Use of the pulmonary autograft for mitral replacement: short- and medium-term experience.

OBJECTIVES: In an effort to find a suitable mitral substitute for our young rheumatic patients who cannot follow a proper anticoagulation regimen for life, we resorted to an old concept reported by one of the authors (D.N.R.) in 1967. This report summarizes our experience with the Ross-mitral operation to date. METHODS: Between 19 June 1997 and 27 June 2000, 43 patients with rheumatic valve disease underwent the Ross-mitral operation. Two patients were excluded because of graft stenosis detected at the end of the procedure for which the autograft had to be sacrificed. Of the remaining 41 patients 29 were female, and the age range was 12--57 years (median 39 years). The autograft was incorporated within a Dacron tubing, with a pericardial collar attached to its proximal end. The conduit was sutured distally to the excised mitral annulus; the pericardium was attached proximally to the atrial wall in 36 patients, and was used simply to cover the Dacron tubing in five patients. The pulmonary artery was replaced with a pulmonary or aortic homograft, or with a pulmonary xenograft. RESULTS: There were two hospital fatalities from a cerebrovascular accident and a lung injury, and two postoperative myocardial infarctions. There were five late deaths, two due to bacterial endocarditis, one due to excessive bleeding at reoperation for a paravalvular leak, and two not related to the procedure. A phenomenon of 'autograft stenosis' occurred intraoperatively in four recent consecutive patients that probably resulted from our use, for the first time, of softer Dacron tubing material. This was repaired in two of the four patients. Echocardiography confirmed excellent functioning of all 34 autografts of surviving patients up to 36 months postoperatively (mean follow-up 18.2 months). Two patients remain in functional Class III status, one due to left heart failure following myocardial infarction, and the other due to recurrent tricuspid insufficiency. CONCLUSIONS: We believe that the mitral pulmonary autograft is a worthwhile alternative to mechanical prostheses in developing countries.

Mitral valve replacement with a pulmonary autograft: initial experience.

BACKGROUND AND AIM OF THE STUDY: For long-term substitution of the mitral valve, mechanical prostheses require life-long anticoagulation which is impractical in developing countries, xenografts degenerate early in our young population, and mitral homografts have not yet been established as being suitable. We therefore returned to an original concept first reported by one of the authors (D.N.R.) in 1967. METHODS: Between July 1997 and November 1998, 22 patients (mean age 40.3 years; range: 28 to 57 years) with rheumatic mitral valve disease unsuitable for reconstruction were subjected to excision of their pulmonary valve in the standard fashion of the Ross procedure. The inverted autograft was incorporated in a 2.5 cm-long Dacron conduit, with a pericardial collar attached to its proximal end. The distal end of the autograft-conduit was sutured to the annulus of the excised mitral valve, and the proximal end incorporating the pericardial collar was attached to the adjacent atrial wall. In this way all prosthetic material was covered. The right ventricular outflow was reconstructed with a pulmonary homograft in 17 patients, with an aortic homograft in two, and with a porcine pulmonary xenograft in three. RESULTS: One patient developed a fatal cerebrovascular accident, probably related to an incorrectly placed pericardial collar with rough surface exposed to the blood flow. In a second patient the autograft had to be replaced six weeks after operation due to bacterial endocarditis contracted in the operating room. Echocardiography confirmed excellent function of the remaining autografts up to 16 months postoperatively (mean follow up 8.3 months). CONCLUSIONS: We believe the pulmonary autograft to be a valid option for mitral valve replacement in our patients.

[Aortic valve replacement with a pulmonary autograft (the Ross operation) in adult and pediatric patients. A preliminary study]. / Reemplazamiento valvular aórtico con autoinjerto pulmonar (operación de Ross), en pacientes adultos y pediátricos. Estudio preliminar.

INTRODUCTION AND OBJECTIVES: Aortic valve replacement with the patients own pulmonary autograft (the Ross procedure) is by now, the best surgical method for the replacement of the diseased aortic valve in certain groups of patients, this is particularly true for young adults and children or neonates with complex left ventricular outflow tract obstructions. The procedure was described by Donald Ross in 1967, and many years have passed. So in view of the accumulated experience the indications have extended to a wide group of patients which include children, neonates and young adults with formal contraindications for anticoagulation. In this publication we present our experience and our preliminary results in a group of fifteen patients which include adult and pediatric. MATERIAL AND METHODS: In six patients the etiology of lesion was congenital and in the remainder nine the valve had an acquired lesion. Two patients had an open heart procedure before this operation both of them to relieve an obstruction to the left ventricular outflow tract. In this group of patients the Ross procedure was carried out inserting the pulmonary autograft in the aortic position as a total root which was always reconstructed with cryopreserved pulmonary homograft, the mean homograft diameter was 26.1 +/- 4 mm (19-35). RESULTS: In all patients a transesophageal echocardiogram was performed in the operating room and postoperative, 1 or 2 months later. Only in one patient a mild aortic regurgitation was detected, no significant transaortic or transpulmonary gradients were detected postoperative. One patient was reoperated for bleeding in the postoperative course, there was no hospital mortality in our group and all the patients had an uneventful postoperative period. In the short term follow-up (41-155 days). All the patients are free of anticoagulant therapy, all them are in New York Heart Association Functional Class I. CONCLUSIONS: The patients presented in this publication which include adult and pediatric, are the first group of patients operated in our country with some excellent preliminary results. We hope that this procedure will become popular and that other surgical groups will adopt it as another surgical tool to replace a diseased aortic valve.

Options for right ventricular outflow tract reconstruction.

The popularity of the Ross operation has drawn attention to the need for a satisfactory replacement of the excised pulmonary valve and artery. Although living autogenous tissue is desirable, it has not been possible to manufacture a satisfactory living conduit, and pulmonary homografts have provided a satisfactory long-term solution. Now, with the increasing shortage of homografts, a number of alternative options have to be considered. The most useful and readily acceptable replacement is a porcine pulmonary xenograft, which is now commercially available. Other prospects for future consideration relate to the use of transgenic pig tissue and developing techniques of tissue engineering. In emergency conditions where a valve conduit is unavailable, a temporary solution is to use a simple tube of autogenous pericardium.

Mitral valve replacement with a pulmonary autograft: the mitral top hat.

Despite previous unsatisfactory results with inverted pulmonary homografts in mitral valve replacement, we have rekindled our interest in this technique by the use of a pulmonary autograft with the fully flexible 'top hat' type of mounting. The surgical technique and the clinical feasibility of the operation are presented.

Pulmonary autograft procedure for aortic valve disease: long-term results of the pioneer series.

BACKGROUND: Pulmonary autograft replacement of the diseased aortic valve has not been widely practiced due to concerns regarding late autograft competence and the consequences of creating pulmonary valve disease. To investigate this, the fate of the pioneering series of patients has been determined. METHODS AND RESULTS: The 131 hospital survivors of the pulmonary autograft operation at the National Heart Hospital from 1967 to 1984 were identified and their outcomes determined to 1994. Age at operation was 11 to 52 years, and 109 patients were male. Autograft implantation was orthotopic subcoronary (107), free-standing root (20), or Dacron mounted (2). In 113 patients, homografts replaced the native pulmonary valve. Ten and 20 years after operation, survival was 85% and 61%, freedom from autograft replacement was 88% and 75%, and freedom from replacement of pulmonary position homografts was 89% and 80%, respectively. Causes of deaths (53) included chronic heart failure (13), complications of reoperation (12), and endocarditis (7). Autograft regurgitation, the most common indication for reoperation, appeared primarily technical in nature, usually due to cusp prolapse. Degeneration was found in only 3 of 30 explanted autografts, and the young patients showed no increase in late valve failure. Homografts outperformed other valve replacements in the pulmonary position, but patients with orthotopic subcoronary and root autografts survived similarly. CONCLUSIONS: The pulmonary autograft offers low rates of degeneration, endocarditis, and thromboembolism for a period lasting >20 years, particularly in the young, with reoperation mainly required for malpositioning of the autograft cusps. The capacity of the autograft to maintain viability with minimal degeneration is not matched by any other biological valve replacement.

Anatomic and physiologic bases for the Ross procedure.

Now that the Ross procedure (RP) has been established as the best method of aortic valve replacement (AVR) in several cohorts of patients, it is appropriate to analyze the evolution, as well as the anatomic and physiologic bases for it. Reviewing the evolution of this operation, one may understand the time lapse between its inception and the universal performance of this procedure. Experimental work began as early as 1927 by Hochrein. He was followed by the Stanford group, Lower in 1960 and 1961, and Pillsbury and Shumway in 1966. Successful clinical application by Donald Ross in 14 patients, two in the mitral and 12 in the aortic positions, was accomplished in 1967. Several important developments followed, including Marcel Geens' study of the blood supply to the ventricular septum in 1971 together with the improvement in surgical results following the initial experience of Gonzalez-Lavin and Ross. Further developments included assessment of the tensile strength of the pulmonary valve (PV) by Gorczynski (1982), ability to grow by Murata (1984), a finding of low Ca++ content of the PV by Livi in 1987 and of excellent hydraulic function by Wareesena in 1994. Finally there was universal acceptance by Elkins, Duran, and others, culminating with the Ross Registry and the establishment of the Ross Colloquium by Oury et al. A review of the anatomical features of the PV are compared with those of the aortic valve (AV), including gross anatomy and relationship to the sinotubular junction, scan microscopy and anisotropic properties of both AV and PV. The blood supply to the ventricular septum will be outlined by reviewing Marcel Geens work. The hemodynamics as reported by several investigators are reviewed. The clinical evidence of growth by Elkins et al. is outlined. Based on this increasing knowledge, indications and contraindications for AVR by the RP are discussed.

False aneurysm: a rare and potentially severe complication after pulmonary autograft operation.

A case of a false aneurysm arising at the proximal suture of an aortic root replacement with a pulmonary autograft is presented. This complication did not occur in the first postoperative month but was discovered late, and the female eight-year-old patient was in an extremely serious condition. She was reoperated on an emergency basis but died of acute pulmonary artery hypertension. The mechanism of the occurrence of such a case is discussed. In the absence of infection, structural weakness of the right ventricular muscle with progressive tearing is suggested. Strict and prolonged echocardiographic surveillance after the Ross procedure and early reoperation are mandatory.

A continuous suture technique for mechanical or bioprosthetic aortic valve replacement.

A continuous suture technique for aortic valve replacement was developed early in our experience. This technique has proved to be simple, quick, effective, and to have several advantages over alternative techniques.

Aortic valve replacement with pulmonary homografts. Early experience.

The increasing use of the aortic homograft as aortic valve substitute and the limited availability of donor valves prompted us to consider the pulmonary homograft as an alternative substitute for aortic valve replacement. The aim of our study is to compare the ultrastructural and biomechanical properties of pulmonary homograft leaflets with those of their aortic counterpart and to present the early results of using the pulmonary homograft for aortic valve replacement. Light and transmission electron microscopy have shown that pulmonary homograft leaflets are thinner than the aortic with a lesser content of elastic tissue in the ventricularis layer. However there were no substantial differences in the ultrastructure. Uniaxial tensile tests were done on 69 cusps from human pulmonary and aortic valves using an Instron testing machine. The strain at 200 KPa was found to be similar for both pulmonary and aortic leaflets (8.20% +/- 2.87% versus 8.98% +/- 1.90%) cut circumferentially. Radial strips appear to be more extensible in pulmonary leaflets than in aortic (32.6% +/- 7.5% and 28.6% +/- 11.1%, respectively). The ultimate tensile strength for circumferential strips was found to be similar for both aortic and pulmonary valves (1460 +/- 857 kPa versus 1450 +/- 689 kPa), but there was relatively little difference between the radial strips (295 +/- 95 kPa versus 252 +/- 104 kPa). A total of 123 patients whose ages ranged between 13 and 78 years received either fresh antibiotic sterilized or cryopreserved pulmonary homografts for aortic valve replacement. The pulmonary homograft was inserted in place of the patient's diseased aortic valve by using one of two different techniques: freehand in the subcoronary position or as a "short cylinder" inside the aortic root. There was three hospital deaths (2.43%; 70% confidence limits = 1.08% to 4.83%). Cumulative follow-up was 184 patient-years (range 1 to 39 months). All surviving patients have been followed up with serial color flow Doppler echocardiography. There were no late deaths. Actuarial late survival was 97.5% (70% confidence limits = 95.7% to 98.6%) at 3 years. Four patients (2.2%/pt-yr) underwent reoperation because of severe aortic regurgitation (1, 4, 12, and 15 months after the operation) because of technical problems (mismatch in size between the pulmonary homograft and aortic anulus) in three patients and probably because of graft rejection in one patient. At 3 years the actuarial rate of freedom from reoperation was 95.5% (70% confidence limits = 92.7% to 97.3%). Mild aortic regurgitation has been detected in three patients (2.6%). No patients incurred thromboembolic episodes or infective endocarditis.(ABSTRACT TRUNCATED AT 400 WORDS)