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Biomedical subjects

W W Angell

Publications and source records attributed to W W Angell.

At least 19 recordsLinked to original sources
PubMed1992

Universal method for insertion of unstented aortic autografts, homografts, and xenografts.

Since the advent of homograft aortic valve replacement surgery in the early 1960s, this procedure has been plagued by early aortic insufficiency. This problem has not been observed with total aortic root replacement. From September 1985 to April 1991, a modified method was used in 25 of 39 consecutive patients having aortic root replacement--seven having autografts, 30 having homografts, and two having xenografts. This technique is a new approach for implanting unstented valves in the aortic position. It decreases the probability of early failure resulting from technical malalignment of the valve during implantation. Further, it avoids the need to destroy the recipient aortic root. Whether the valve being used is an autograft, homograft, or xenograft, this method standardizes the insertion technique regardless of the anatomy or disease. Salient features of the method include the following: a longitudinal aortotomy to the aortic anulus in the midportion of the noncoronary sinus; a proximal interrupted suture line with the valve oriented in the anatomic position; and circumferential running monofilament side-to-side approximation of the donor coronary ostia to the recipient coronary ostia. The two anterior commissures are left untethered by nonclosure of the recipient aortotomy. Preliminary results have been impressive, with follow-up ranging from 1 to 3 years in 30 of these patients. Postoperative aortic insufficiency was significant in only two cases. There has been no progression of aortic insufficiency detectable by diastolic murmur or echocardiogram. Late complications have been minimal, and the overall clinical results have been excellent.

Adolescent↗
PubMed1991

Bioprosthetic valve durability in the elderly: the second decade.

With an increasing number of elderly patients requiring cardiac valve surgery, the topic of bioprosthetic durability becomes critically important. Previous reports have shown expected survival of bioprosthetic valves to be in excess of 95% at 9 years. However, primary tissue failure appears to accelerate at the end of the first decade and there is limited data into the second decade. With this in mind, we proceeded to analyze all bioprosthetic valves implanted in patients 70 years of age and older. From September 1974 to December 1990, 781 patients underwent valve replacement using a bioprosthesis. Ages ranged from 70 to 88 years with a mean of 75.1. There were 423 males (54.2%) and 358 females (45.8%). Preoperatively, 99.0% of the patients were in either New York Heart Association functional Class III or IV. Fifty-nine patients (7.6%) were done as emergencies. Six hundred ninety-four patients left the hospital (30-day overall mortality 11.1%). In this cohort, there were 733 valves at risk. Follow-up extended from 1 to 186.0 months with a mean of 52.9, which resulted in 3,059.9 patient-years of cumulative follow-up. Bioprosthetic Survival: A total of 23 valves failed in the series; 15 primary tissue failures, seven from endocarditis, and one perivalvular leak. Actuarial survival at 7 years was 94.5% +/- 1.4% standard error of the mean (SEM; 168 valves at risk) and at 13 years, 83.7% +/- 4.8% SEM (11 valves at risk). This analysis provides further documentation of the long-term favorable durability of the bioprosthesis when utilized in patients 70 years of age and over.

Actuarial Analysis↗
PubMed1991

Effect of stent mounting on tissue valves for aortic valve replacement.

Stent mounting of homograft valves was first reported by our group in 1968. Since then, there has been question as to whether or not stent mounting of bioprostheses adversely affects the incidence of structural deterioration in aortic valve replacement. Between November 1967 and July 1988, 571 consecutive patients underwent valve replacement with a stented or unstented homograft. There were 351 men (61.5%) and 220 women (38.5%). The mean age of the group was 49.2 years (range 18 to 79 years). Five hundred thirty-four patients left the hospital (30-day overall mortality 6.5%). Follow-up extends from 6 months to 22 years with a mean of 7.6 years. The cumulative follow-up for the series was 4,095.9 patient-years. Hospital mortality, early technical failure, and prosthetic valve endocarditis were considered censoring events and excluded from this study. Actuarial analysis revealed a significant difference (p less than 0.02) in the freedom from structural valve deterioration for unstented and stended isolated aortic valve replacement. Age (50 and under, and over 50) does not appear to be a factor in structural deterioration in unstented homografts but does influence the rate of failure in stented homografts (p less than 0.05). These results clearly indicate that stent mounting adversely affects tissue valve durability with aortic valve replacement. Moreover, age correlates with structural deterioration if valves are stented and does not if they are unstented. Based on these results, the use of unstented bioprostheses should be reevaluated, along with the design of porcine valve stents.

Adolescent↗
PubMed1991

Unstented and partial stented bioprostheses for aortic valve replacement--up to 6 years of follow-up.

Since January 8, 1985, three different designs of unstented (type A, n = 9) and partial stented (type B, n = 4; and type C, n = 3) glutaraldehyde preserved porcine aortic valves were used for aortic valve replacement in 16 patients with acquired aortic valve lesions. Type A and type B prostheses were implanted using a two suture row technique. In type C prostheses, only a single suture row was necessary for implantation, facilitating surgery considerably. In all patients, the fully flexible commissures of the bioprostheses were secured to the aortic wall of the recipient. There was no hospital mortality. Two patients with type A bioprostheses died due to noncardiac causes, 4 and 24 months postoperatively. One bioprosthesis in this group had to be replaced after 3 months because of insufficiency. Serial Doppler echocardiographic studies were performed up to 6 years after implantation. No significant leaflet calcification was observed. In three type A bioprostheses, a mild insufficiency without progression was recorded. The latest mean/peak transprosthetic pressure gradients were: type A: 6 +/- 4 mmHg/12 +/- 6 mmHg; type B: 6 +/- 3 mmHg/14 +/- 5 mmHg; and type C: 11 +/- 5 mmHg/18 +/- 8 mmHg. The functional results of the type A and type B bioprostheses have proven to be satisfactory. The slightly higher pressure gradients in patients with a type C bioprosthesis give rise to further refinements of its design. These results confirm the usefulness of imitating normal anatomy by using unstented or partial stented bioprostheses.

Adult↗
PubMed1989

Twenty-year comparison of the human allograft and porcine xenograft.

This study compares a retrospective consecutive series of human allografts and concurrent porcine xenografts implanted over a 10-year interval. There were 571 allograft valves and 1,351 xenograft valves implanted in the aortic and mitral position with mean follow-up of 12.8 years for the allografts and 6.2 years for the xenografts. This study compares the incidence of structural deterioration over long-term follow-up. We found that there was no significant difference between four manufacturers of porcine xenografts, in spite of substantial differences in processing techniques. We found that there was a significant difference in allografts that were premounted on stents as compared with allografts that were not premounted on stents for aortic valve replacement. We found that there was no significant difference between allografts for aortic valve replacement that were not premounted on stents and porcine xenografts implanted in the aortic position. These findings are in marked contrast to those of other reported series with the use of allograft valves.

Animals↗
PubMed1989

Durability of the viable aortic allograft.

Of 581 aortic allografts implanted since 1967, 421 were analyzed for structural deterioration. This series is unique in that it includes patients from the early allograft experience. All allografts were cleanly procured, antibiotic sterilized, and either stored at 4 degrees C for up to 8 weeks or frozen to liquid nitrogen temperatures with cryopreservation to preserve the viable cusp fibroblasts. There were 25 frozen mounted aortic valves with a median time to valve failure of 12.1 years, which was not significantly different from the 12.5-year period for 114 fresh free-sewn aortic valves. The median time to valve failure was 6.6 years for 90 fresh-mounted aortic valves and 8.6 years for 192 fresh-mounted mitral valves (p = 0.05). The difference between all mounted and unmounted grafts was significant (p = 0.0001). In all groups, viable fibroblasts were present in specimens explanted up to 5 years after the operation. All specimens returned after more than 10 years were almost totally acellular. Evidence of increased collagen, suggesting that the fibroblasts survive implantation and then gradually die, was present in all specimens. This series suggests that durability of the unmounted viable allograft for aortic valve replacement is greater than for other types of tissue valves. Pre-mounted allografts for aortic or mitral valve replacement have a median survival of 8 years and are not more durable than other tissue valves.

Aortic Valve↗
PubMed1988

The cryopreserved homograft valve in the pulmonary position: early results and technical considerations.

Since September, 1985, 20 patients have undergone implantation of a homograft valve in the pulmonary position (16 pulmonary, 4 aortic). There were 11 primary operations and 9 reoperations. In 7 of 11 primary operations the homograft valve was utilized as a composite conduit with a short Dacron extension. In four of five reoperations for a failed porcine valved conduit, a composite homograft conduit was used. Four patients underwent implantation of a free homograft in a previously repaired right ventricular outflow tract (RVOT). Age ranged from 15 days to 22 years. There was one operative death (5%), a seven-week-old infant with truncus arteriosus. Long-term follow-up ranges from 1 to 30 months. Clinical performance has been satisfactory in 18 of 19 patients. One patient undergoing free implantation of a pulmonary valve in the RVOT required replacement at 18 months with a porcine valve. In this patient, pulmonary insufficiency was caused by distortion of the annulus secondary to dilatation and pulmonary hypertension. Nine of 18 survivors do not require medication. Eleven of 18 have trivial to mild pulmonary insufficiency murmurs without symptomatology. The homograft valve is extremely useful in reconstruction of the right heart, however, early insufficiency murmurs have been noted. Distortion of the valve annulus may contribute to the early onset of a benign insufficiency murmur. Residual distal obstruction or pulmonary hypertension may be a contraindication to the use of a free homograft in the orthotopic position.

Adolescent↗
PubMed1988

Long-term fate of valve cusp patches for right ventricular outflow tract reconstruction.

Six patients with tetralogy of Fallot, pulmonary atresia, or absent pulmonary valve syndrome were operated with a RVOT patch containing a single aortic allograft cusp from an adult donor. The method was based on animal work with similar patches implanted in growing puppies and proved that the single cusp functioned as an effective RV outflow valve for several weeks after surgery. Postoperative angiograms in the animals confirmed nearly completely competent valves. Sacrifice of animals at 3 months documented that the allograft tissue was flexible without early deterioration or calcification. Clinical application of this method raised several questions regarding the procedure, its efficacy, and subsequent fate of the allograft valve in children requiring RVOT reconstruction. There were six children age 19 months to 10 years who required division of the pulmonary valve annulus to relieve pulmonary outflow obstruction or with absent pulmonary valve syndrome and compromised airways from pulmonary insufficiency. One patient had a positive culture from the valve and required immediate removal of the infected allograft. Patients had clinically competent pulmonary valves immediately after surgery with decreased right ventricular systolic and end-diastolic pressures when compared with patients in whom nonvalve patches were inserted. All patients had some degree of pulmonary insufficiency, but no symptoms. Follow-up up of five patients available 4 to 6 years after surgery revealed no patients with stenosis of the valve cusps, although two patients have severe, one moderate, and two mild pulmonary insufficiency. We conclude that a patch containing a single adult allograft valve cusp should be considered for all patients requiring reconstruction of the RVOT, particularly if RV overload is expected to compromise the immediate postoperative result.

Animals↗
PubMed1988

Comparison of Hancock I and Hancock II bioprostheses.

The Hancock II bioprosthesis was developed in order to provide the advantageous low pressure fixation, improved delrin stent design, and anticalcification treatment. These changes were made 6 years ago after 10 years of experience with the high pressure fixed rigid implantation ring and polypropylene stent used in the Hancock I valve. In 1983, based on our own experience with low pressure fixed valves in 76 patients, we began early clinical trials with the Hancock II valve. All valves were studied postoperatively by intraoperative catheterization and followed up with postoperative echocardiograms for measurement of valve gradients and areas. This series of 104 patients with Hancock II valves was then compared retrospectively with 119 patients receiving Hancock I valves from 1975 to 1983. A comparison of mortality, thromboembolism, and hemorrhage rates was not significantly different between groups and the valve failure incidence of Hancock I valves was an anticipated 2.34% per patient-year. There has been one primary tissue failure in the Hancock II series. This patient had fibrinous excrescences on the outflow surface of the valve in the aortic position. These nodules were compatible with an old thrombotic process of ill-defined nature. Further investigation resulted in reports of this phenomenon, which had resulted in early valve stenosis, from other centers implanting the Hancock II valve. In conclusion, the Hancock II bioprosthesis has theoretical advantages over the Hancock I in stent design, fixation pressure, and anticalcification potential. There is an unusual thrombotic process in aortic valve replacements that we have not observed in the Hancock I group or in our experience with other porcine xenografts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Experience with Damus procedure.

Sixteen patients with complex cyanotic congenital heart disease underwent an operation involving the use of the aorta and the main pulmonary artery as the egress for systemic arterial blood flow (the Damus-Kaye-Stansell operation, modified as discussed). The indication for this approach was either preoperative aortic outlet obstruction or likelihood that the repair would produce such obstruction. A modification of the original technique is introduced that involves transection of both great arteries, anastomosis of the contiguous aortic and pulmonic walls, and connection of the distal aorta to the perimeter of the new (bivalved) great artery. Eleven of the 16 patients survived operation: six of six who underwent a concurrent Fontan operation, four of six who underwent a concurrent right-ventricle-to-pulmonary-artery-conduit procedure, and one of four who underwent a concurrent systemic-pulmonary shunt procedure. Postoperative status in the 11 survivors is good: one patient has a gradient from the left ventricle to the aorta, 10 of 11 have little or no aortic regurgitation, and the remaining patients have a normal physiological status. We conclude that the Damus procedure is a useful addition to the surgical armamentarium for treatment of certain types of cyanotic congenital heart disease.

Angiography↗
PubMed1987

A comparison of replacement and reconstruction in patients with mitral regurgitation.

The factors that make mitral reconstruction an attractive alternative to valve replacement are increased anatomical valve orifice, preservation of the valvular apparatus, improved longevity over porcine xenografts, and no requirement for long-term anticoagulation. In our experience the majority of patients with mitral regurgitation have degenerative valve disease. This comparative series of patients operated on over a 10 year interval includes 72 with replacement and 112 with reconstruction. The average cross-clamp times were 69 minutes for reconstruction and 44 minutes for replacement. The hospital mortalities were 3.6% and 18.1%, respectively. Postoperative valve areas as determined by Doppler echocardiography were 2.69 cm2 for replacement and 2.67 cm2 for reconstruction (p = 0.9). The valve failure rate was 2.0% per patient-year for reconstruction and there were no failures in the replacement group. The reoperation incidence for reconstruction was 20% at 10 years. The remaining patients, although clinically well, had varying degrees of stable, nonprogressive mitral regurgitation. Forty-five percent had mild to trivial regurgitation detectable by echocardiographic studies. The decision between mitral valve reconstruction and mitral valve replacement remains a highly controversial issue. The failure of our data to demonstrate superior valve function for patients with mitral regurgitation undergoing valve reconstruction suggests a need for careful analysis of reconstruction with respect to effective valve orifice and incidence of regurgitation.

Bioprosthesis↗
PubMed1987

Long-term follow-up of viable frozen aortic homografts. A viable homograft valve bank.

There is currently a renewed interest in the use of both fresh and commercially available frozen homograft valves for children and young adults. This has prompted us to review a series of 32 patients who received frozen homograft valves for aortic replacement between 1973 and 1975. The cryogenic technique evolved to include the use of selected antibiotics and equilibrated dimethyl sulfoxide solution to freeze homografts at a rate of 1 degrees C per minute to liquid nitrogen temperatures of -196 degrees C. Histologic sections of experimental frozen valves explanted 6 months postoperatively revealed the presence of viable donor cells, and tissue culture demonstrated the reproductive capacity of cusp fibroblasts. Of the 32 frozen viable homografts implanted in this series, 23 were inserted as free-sewn aortic replacements and nine were premounted on stents before implantation in the aortic position. There were two operative deaths, and three valves failed as a result of the technical problems of mounting in one patient and surgical insertion of a free graft in two patients. Of the 22 patients who remained at long-term risk, 13% with free-sewn grafts and 57% with premounted valves underwent reoperation for valve failure. After 10 years of follow-up, 15 (68%) of these patients, 12 (80%) with free-sewn and three (43%) with premounted valves, are alive with their original valve in place. Actuarial analysis shows that 58% of the 32 valves implanted are functional at the beginning of the eleventh year. There have been six late deaths resulting in an overall actuarial patient survival rate of 79% at 10 years and 69% after 13 years. These clinical results are believed to add support to our current application of the frozen homograft in selected patients.

Adult↗
PubMed1982

Twelve-year experience with glutaraldehyde-preserved porcine xenografts.

Three hundred fifty-two patients underwent aortic (AVR) or mitral (MVR) valve replacement with a glutaraldehyde-preserved porcine xenograft from 1970 to 1980. Analysis of this series revealed the following information: hospital mortality, 11.6% (41/352); late mortality, 5.5% per patient-year (60/1,090.7); actuarial 5 year survival rate, 70%; incidence of thromboembolism and hemorrhage, 1.4% per patient-year (15/1,090.7); incidence of spontaneous degeneration, 1.1% per patient-year (12/1,090.7); and transvalvular gradient. AVR 16 mm Hg and MVR 4.6 mm Hg. These results compare favorably with results from other porcine xenograft series and with those reported for prosthetic valves. There is no apparent difference in the type of xenograft used with the exception that spontaneous degeneration occurred less frequently in mitral valves that had not undergone pressure fixation than in those that had. The use of flexible stents improved the ease of valve implantation but did not affect leaflet durability as anticipated. Calcification occurred randomly with no relationship to time of implantation. Reoperation was for spontaneous valve deterioration by calcification or collagen degeneration in 11 cases, paravalvular leak in 13 cases, and implantation of an undersized valve in four cases; there was one reoperation for infection. Results support the continued use of porcine xenografts and suggest that improved manufacturing techniques will reduce the incidence of spontaneous, sterile deterioration, which is the only serious drawback to routine use of the porcine xenograft.

Aged↗
PubMed1979

The Angell-Shiley porcine xenograft.

A 4-year clinical experience with fresh allograft tissue valves prompted a trial of 0.5% buffered glutaraldehyde as a valve fixative and sterilant. Tanned allograft and porcine xenograft valves were inserted into experimental animals, and, beginning in 1970, similar valves were implanted in a series of patients now totaling 312. The clinical results are excellent. The 5-year valve-related mortality is 6% for patients who had mitral valve replacement and 16% for those with aortic valve replacement. To date, the incidence of thromboembolism is 1.3% per patient-year, and valve-related morbidity and mortality for the combined groups is 27.4%. Valve stent design has evolved from symmetrically configured metal to anatomically molded plastic. The maintenance of natural valve configuration has optimized leaflet coaptation and support, decreased tissue stress, and eliminated valve-stent dehiscence and tissue rupture seen in valves deformed to fit symmetrical stents. Stent design, controlled glutaraldehyde solutions, and fixation techniques have improved leaflet flexibility and reduced valve orifice to annulus diameter ratios, thus producing transvalvular gradients comparable to both mechanical and modified orifice tissue valves. To date, tissue failure, observed in only 1.0% (3 of 287) of patients, is the result of calcification (2 patients) and cusp rupture due to incomplete fixation (1 patient).

Adult↗