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Biomedical subjects

D N Ross

Publications and source records attributed to D N Ross.

At least 19 recordsLinked to original sources
PubMed1996

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.

Aortic Valve↗
PubMed1996

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.

Aneurysm, False↗
PubMed1994

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)

Actuarial Analysis↗
PubMed1993

Balloon dilatation of a bioprosthetic pulmonary valve.

A 37-year-old man with stenosis of a bioprosthetic pulmonary valve underwent percutaneous balloon valvoplasty. After the procedure the patient had moderate pulmonary regurgitation which has been well tolerated. The patient remains well with good functional capacity on follow-up at 2 years. Percutaneous balloon dilatation may be effective as a palliative procedure in the management of stenosis of a bioprosthetic valve in the pulmonary position.

Adult↗
PubMed1993

Primary repair and autotransplantation of cardiac valves.

The aortic valve is a beautifully designed and balanced structure with precise opening and closing mechanisms. Its design probably cannot be improved upon by man-made mechanical devices, no matter how ingenious. It is logical to use human valves as replacements because of their superior structural configuration. Their chief difficulties are in the troubles of the learning curve of the surgeon to achieve a competent mechanism and the hazard of infection. The pulmonary autograft or translocation of the pulmonary valve to the aortic position offers many advantages, and the long-term results are good. Conservative repair and reconstruction of the aortic valve are increasing in popularity but have a relatively limited application. The mitral valve has a less precise and more adjustable type of mechanism and generous leaflet coaptation. These features make it more amenable to repair, as demonstrated in the clinical series of the technique. Repair is clearly preferable to replacement at present. The tricuspid valve is eminently suitable for reconstruction, but late results are not very good. The disappointing outcome, however, reflects more the severity of underlying cardiac pathology than the effectiveness of the repair.

Heart Valves↗
PubMed1991

Replacement of the aortic valve or root with a pulmonary autograft in children.

Between January 1967 and December 1988, 34 patients ranging in age from 3 to 18 years (mean, 14 +/- 3.6 years) underwent replacement of the aortic valve or root with their own pulmonary valve. The indication for operation was left ventricular outflow obstruction in 16 patients (47%), aortic regurgitation in 14 (41%), mixed aortic valve disease in 3 (9%), and failure of a previously implanted aortic homograft in 1 (3%). There were four early deaths, all before 1971, giving a hospital mortality of 11.8% (70% confidence interval, 6% to 20%). Surviving patients have been followed up a cumulative total of 214 patient-years, the longest period of observation being 16 years 8 months. Late mortality was 13.3% (70% confidence interval, 7% to 23%), and 4 other patients required removal of the pulmonary autograft for endocarditis. Actuarial rates at 16 years were 74% +/- 11% for freedom from reoperation on the left ventricular outflow tract, 80% +/- 10% for freedom from reoperation on the right ventricular outflow tract, and 77% +/- 10% for late survival. There was no instance of primary structural degeneration in the pulmonary autograft, and all surviving patients were in New York Heart Association functional class I without medication. This experience demonstrates that the pulmonary autograft can achieve good early and medium-term results in young patients. Should growth potential be realized, it might constitute the ideal biological valve for the left ventricular outflow in children.

Adolescent↗
PubMed1991

Treatment of complicated prosthetic aortic valve endocarditis with annular abscess formation by homograft aortic root replacement.

The outcome of 30 consecutive patients with active aortic prosthetic valve endocarditis and root abscesses treated by the technique of homograft aortic root replacement with reimplantation of the coronary arteries is detailed. The principles of this technique are the removal of all abscesses and infected areas likely to drain into the infected mediastinum, excision of infected tissues down to healthy noninfected tissue and replacement with an antibiotic-impregnated homograft aortic root. All patients had evidence of progressive cardiac failure and ongoing sepsis. Mean patient age (+/- SD) at the time of operation was 42 +/- 18 years. The mean number of previous aortic valve replacements per patient was 1.6 +/- 0.7; 14 patients (47%) had undergone greater than or equal to 2 previous replacements. At operation, aortic root abscesses were found in all patients; abscess extension to adjacent structures and partial valve dehiscence had occurred in 23. In-hospital death occurred in 9 (30%) of the 30 patients. The 21 hospital survivors have been followed up for a mean of 66 +/- 42 months (range 9 to 144). Overall, 17 (81%) of the 21 hospital survivors have remained free of major adverse events (recurrence of endocarditis, need for reoperation or death). The results of our study suggest that homograft aortic root replacement should be considered favorably in the treatment of patients with aortic prosthetic valve endocarditis and root abscesses.

Abscess↗
PubMed1991

Comparison of the aortic homograft and the pulmonary autograft for aortic valve or root replacement in children.

To assess late results of aortic homograft and pulmonary autograft valves implanted into the left ventricular outflow tract of children, we reviewed the case histories of 146 patients 18 years of age or younger who underwent aortic valve or root replacement between November 1964 and April 1990. One hundred three patients (mean, 12 +/- 3.9 years) received an aortic homograft and 43 (mean, 14 +/- 4.1 years) had their own pulmonary valve transferred to the aortic position. There were 54 valve and 49 root replacements with homografts and 36 valve and seven root replacements with autografts. Hospital mortality rate was 15.5% (16 patients) in the homograft group and 11.6% (five patients) in the autograft group. Survivors were followed up for a total of 867 (homograft) and 297 (autograft) patient-years. The late mortality rate was 16.7% (1.9% per patient-year) for patients with homografts and 13.2% (4.4% per patient-year) for patients with autografts, whereas the incidence for reoperation per patient-year was 2.9% and 2.0%, respectively. At 15 years actuarial rates for homografts and autografts for freedom from reoperation were 54% +/- 8.1% and 68% +/- 11.1%; freedom from endocarditis, 97% +/- 2.4% and 75% +/- 10.2%; and freedom from any complication, 41% +/- 6.5% and 50% +/- 10.3%. Valve degeneration occurred in 19 homografts (2.2% per patient-year), whereas there was no definite instance of primary tissue failure among the pulmonary autografts. This experience would indicate that either the homograft or the autograft valve can be used with acceptable results in children. However, the pulmonary autograft gives better long-term performance and, if growth potential is realized, may be the ideal valve substitute in children.

Adolescent↗
PubMed1989

Viable and nonviable aortic homografts in the subcoronary position: a comparative study.

One hundred fifty-five freeze-dried, 63 frozen, and 337 Hanks'-antibiotic solution preserved or nutrient-antibiotic solution preserved homografts used for isolated aortic valve replacement have been followed for 1 to 20 years (mean, 5.3 years), a total of 2,931 patient-years of follow-up information. Overall survival, valve-related death, primary tissue failure, failure due to surgical technical error, infective endocarditis, and overall event-free survival have been assessed and compared. Overall survival 20 years after operation was 51.6% +/- 8.1% with a low incidence of sudden death. The method and length of preservation did not have any effect on the long-term performance or the mode of failure of the homografts. The rate of primary tissue failure was apparently higher with valves preserved in a solution containing calf serum, but the difference was not significant. It is concluded that long-term patient survival and quality of life after aortic valve replacement with a homograft are excellent. The current study, however, could not verify the existence of a significant difference between the three assessed methods of homograft preservation. Furthermore, it could not prove the importance of cellular viability or the existence of clinically significant immunological factors other than the calf serum content of the nutrient medium.

Adult↗
PubMed1989

Use of an intraaortic balloon pump as a pneumatic ventricular assist device controller.

Using a circulatory analogue, we investigated sequentially the performance of a dedicated ventricular assist device driver and an intraaortic balloon pump when driving a pneumatic ventricular assist device. Each drive device was compared under identical pumping conditions at rates of 40 to 120 cycles/min against two resistances. Our preliminary study showed that a modified intraaortic balloon pump could drive a pneumatic ventricular assist device as effectively as its dedicated driver. The necessary modifications to and possible further development of the intraaortic balloon in this role are discussed.

Assisted Circulation↗
PubMed1988

Heterologous antigenicity induced in human aortic homografts during preservation.

A series of rabbit experiments has been carried out to investigate the potential antigenicity of the heat-treated foetal calf serum which is commonly used to enhance viability of preserved aortic homograft valves. In all presensitised animals, the calf serum content of the nutrient medium which infiltrated the aortic wall during preservation provoked a heavy second-set reaction. It is concluded that heat-treated foetal calf serum is a potent heterologous antigen and should not be used for preserving human tissue selected for transplantation.

Animals↗