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Biomedical subjects

T E David

Publications and source records attributed to T E David.

At least 37 records · Page 2Linked to original sources
PubMed2000

Dilation of the pulmonary autograft after the Ross procedure.

OBJECTIVE: Dilation of pulmonary autograft after the Ross procedure is being recognized with increasing frequency. This study was undertaken to examine the extent of this problem and factors that may be associated with it. METHODS: The clinical, operative, and echocardiographic data of 118 patients who underwent the Ross procedure were reviewed. The mean age of 79 men and 39 women was 34 +/- 9 years, range 17 to 57 years. Bicuspid or other congenital aortic valve disease was present in 81% of patients. The pulmonary autograft was sutured as a valve in the subcoronary position in 2 patients, as a root inside of the aortic root in 45, and was used for complete aortic root replacement in 71. Teflon felt was not used to buttress the proximal or the distal anastomosis of the pulmonary autograft. The diameters of the sinuses of Valsalva, aortic anulus, and sinotubular junction were measured early and late after the operation with echocardiography. The mean follow-up was 44 months. RESULTS: The diameter of the sinuses of Valsalva increased from 31.4 +/- 0.4 mm to 33.7 +/- 0.5 mm (P =.01). Analysis of covariance revealed a significant change over time in this diameter, as well as a difference between operative techniques, with replacement of the aortic root being associated with a higher risk of dilation (P =. 0006). In 13 patients the diameter ranged from 40 to 51 mm. The diameter of the aortic anulus decreased in most patients and increased in 15, but there was no interaction between these changes and the operative technique. The diameter of the sinotubular junction increased in patients who had aortic root replacement and decreased in patients who had aortic root inclusion (P =.007). Moderate aortic insufficiency developed in 7 patients, and 3 required replacement of the pulmonary autograft. All patients with moderate aortic insufficiency had dilation of the aortic anulus and/or sinotubular junction. CONCLUSIONS: Dilation of the pulmonary autograft after the Ross procedure may occur because of an intrinsic abnormality of the pulmonary root in patients with congenital aortic valve disease. The technique of aortic root replacement is associated with a higher risk of dilation of the sinuses of Valsalva and sinotubular junction than the technique of aortic root inclusion.

Adolescent↗
PubMed2000

Mitral valve repair and replacement for rheumatic disease.

OBJECTIVES: Mitral valve repair may be technically feasible in patients with suitable anatomy, but the appropriateness of repair for rheumatic disease remains controversial. We evaluated our late outcomes after mitral repair and replacement for rheumatic disease. METHODS: Five hundred seventy-three patients underwent mitral valve surgery for rheumatic disease at our institution from 1978-1995. Follow-up was 98% complete (mean, 68 +/- 46 months). Survival and morbidity were evaluated by Kaplan-Meier analysis and Cox regression, including propensity score analysis. RESULTS: Mean age was 54 +/- 14 years, 55% of patients had congestive heart failure, 22% were undergoing redo mitral valve surgery, and 9% also underwent coronary bypass. Mitral stenosis was present in 53%, regurgitation in 15%, and both in 32%. Valve repair was performed in 25%, bioprosthetic replacement was performed in 28%, and a mechanical valve was placed in 47%. Patients undergoing repair were younger and less likely to be undergoing reoperation or to have atrial fibrillation than those undergoing replacement (P =.001). The operative mortality rate was 4. 2%. Better late cardiac survival was independently predicted by valve repair rather than replacement (P =.04) after adjustment for baseline differences between patients. Freedom from reoperation was greatest (P =.005) but that from thromboembolic complications was worst (P <.0001) after mechanical valve replacement. Twenty-three patients underwent reoperation after initial repair, with no operative deaths. CONCLUSIONS: Mechanical valves minimize reoperation but limit survival and increase thromboembolic complications. Patients undergoing valve repair had improved late cardiac survival independent of their preoperative characteristics. Rheumatic mitral valves should be repaired when technically feasible, accepting a risk of reoperation, to maximize survival and reduce morbidity.

Adult↗
PubMed2000

Results of surgery for aortic root aneurysm in patients with the Marfan syndrome.

OBJECTIVE: To evaluate the results of two operations, aortic valve-sparing and aortic root replacement, in patients with aortic root aneurysm and the Marfan syndrome. METHODS: A retrospective review of 78 consecutive patients with aortic root aneurysm and the Marfan syndrome according to the Gent criteria indicated that 42 patients with normal aortic cusps had an aortic valve-sparing operation, and 36 patients had aortic root replacement (mechanical valve in 25 patients and biological valve in 11). The mean age was similar in both groups, but patients who had aortic root replacement had larger aneurysms, higher grade aortic insufficiency, worse left ventricular function and more cardiac co-morbidity than patients who had aortic valve-sparing operations. The mean follow-up was 41+/-35 months for patients who had aortic valve-sparing, and 65+/-50 months for those who had aortic root replacement. RESULTS: Kaplan-Meyer estimates of survival at 5 years was 100% for patients who had aortic valve-sparing, and 88+/-6% for those who had aortic root replacement (P=0.04). Five patients who had aortic root replacement required seven aortic root re-replacements: three for endocarditis and four for valve failure (biological valves). There have been no reoperations in patients who had aortic valve-sparing operations and annual Doppler echocardiography revealed mild or no aortic insufficiency in 39 patients and moderate aortic insufficiency in three. CONCLUSIONS: These data suggest that aortic valve-sparing operations are safe in patients with the Marfan syndrome and may provide better clinical outcomes than aortic root replacement. Since the size of the aneurysm often determines the feasibility of a valve-sparing procedure, we now recommend surgery when the diameter of the aortic root reaches 50 mm in patients with the Marfan syndrome who have echocardiographically normal aortic valve cusps.

Adolescent↗
PubMed2000

Intracardiac extension of intravenous leiomyomatosis in a pregnant woman: A case report and review of the literature.

Intravenous leiomyomatosis is an uncommon clinical entity characterized by the growth of a benign, smooth muscle tumour within the venous system. Intracardiac extension of this tumour is rare, and approximately 35 cases have been reported in the literature. The second case of massive intracardiac extension of intravenous leiomyomatosis is reported in a pregnant patient diagnosed after the unusual presentation of seizure activity. Tumours were successfully removed from the right internal iliac vein, inferior vena cava, and right atrium and ventricle in a single-stage operation using cardiopulmonary bypass and circulatory arrest. Concomitant total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed. Nine months after diagnosis, the patient was evaluated for recurrent disease. A review of the literature from 1994 to 1998 is presented.

Adult↗
PubMed1999

Should the pericardium be closed routinely after heart operations?

BACKGROUND: Repeat coronary artery bypass grafting is more difficult if the right ventricle is firmly attached to the inner table of the sternum. Closure of the pericardium at the time of the initial procedure may prevent attachment of the right ventricle to the sternum. This study attempts to identify the geometric effects of pericardial closure early after isolated coronary artery bypass grafting. METHODS: Forty-two patients undergoing elective, isolated coronary artery bypass grafting were randomized into two groups: 20 patients underwent closure of the pericardium (Closure group) and the pericardium was left open in 22 patients (Open group). Radiopaque markers were attached to the anterior aspect of the right ventricular epicardium in both groups. RESULTS: Postoperative chest roentgenograms revealed that the distance between the epicardial surface and the posterior table of the sternum was larger in the Closure group compared to the Open group at 1 week and 3 months postoperatively (p < 0.001). Cardiac index and stroke work index in the early postoperative period was lower in the Closure group compared to the Open group (p < 0.001) despite similar filling pressures. CONCLUSIONS: Pericardial closure may reduce the risk of myocardial injury during sternotomy for repeat coronary artery bypass grafting by preventing right ventricular adhesions. However, adverse hemodynamic effects in the early postoperative period may preclude pericardial closure in patients with impaired ventricular function.

Aged↗
PubMed1999

Surgery for acute type A aortic dissection.

BACKGROUND: Several innovative approaches have been introduced in the surgical treatment of acute type A aortic dissection. This study examines the effects of these new techniques on the early and late outcomes of patients with this disease. METHODS: The records of patients who had surgery for acute type A aortic dissection during an 18 year interval were reviewed. There were 109 patients: 81 men and 28 women, with a mean age of 57 years, range 23 to 80. Most patients were acutely ill and 15 were in shock at the time of surgery. Operations were performed under cardiopulmonary bypass with femoral artery and right atrial cannulation. In 55 patients, the aorta was clamped and retrograde femoral perfusion was used throughout the procedure (group I). In 54 patients, no clamp was used; under circulatory arrest the primary tear was resected whether in the ascending aorta or transverse arch, and antegrade cardiopulmonary bypass was started after completion of the distal anastomosis (group II). Postoperative computed tomographic or magnetic resonance scans were completed annually. RESULTS: There were 16 operative deaths (15%): 11 (20%) in group I, and 5 (9.2%) in group II (p = 0.10). There were 10 strokes: 8 (14.5%) in group I and 2 (3.7%) in group II (p = 0.05). After a mean follow-up time of 59 +/- 45 months for group I, 31 (56%) patients were alive, and after a mean follow-up time of 45 +/- 26 months for group II, 44 (81%) patients were alive. The actuarial survival of group II was higher than group I, but the difference was not significant (p = 0.09). Postoperatively, a patent false lumen was found in 91% of group I patients and in 59% of group II (p = 0.01). CONCLUSIONS: This study suggests that avoidance of aortic clamping, resection of the primary tear in the ascending aorta or transverse arch, and antegrade perfusion after completion of the distal anastomosis improve the early and late outcomes of surgery for acute type A aortic dissection.

Acute Disease↗
PubMed1999

Aortic valve sparing operations: an update.

BACKGROUND: Aortic valve sparing operations in patients with ascending aorta and/or aortic root aneurysms have been performed for a decade in our institution. Initially only patients with normal aortic valve leaflets had these operations, but more recently we utilized them in patients with prolapse of a single leaflet and in those with a bicuspid aortic valve. This article is an update on the clinical results of these operations. METHODS: From May 1988 to December 1997, 126 patients with ascending aorta and/or aortic root aneurysms and aortic insufficiency underwent replacement of the ascending aorta with reconstruction of the aortic root and preservation of the native aortic valve. There were 85 men and 41 women, with a mean age of 54 years (range, 14 to 84). Thirty-two patients had the Marfan syndrome; 17 patients had acute and 10 had chronic type A aortic dissection; 23 had a transverse arch aneurysm; 26 had coronary artery disease, and 8 had mitral regurgitation. The aortic valve sparing operation consisted of simple adjustment of the sinotubular junction in 33 patients, adjustment of the sinotubular junction and replacement of one or more aortic sinuses in 60, and reimplantation of the aortic valve in a tubular Dacron (C.R. Bard, Haverhill, PA) graft in 33. Fifteen patients also had repair of aortic leaflet prolapse. Only 4 patients had a bicuspid aortic valve. RESULTS: There were 3 operative deaths due to cardiac failure. Patients were followed from 2 to 117 months, with a mean of 31. There were 11 late deaths: 7 cardiovascular and 4 from unrelated causes. The actuarial survival was 72 +/- 8% at 7 years. Two patients required aortic valve replacement; the freedom from aortic valve replacement was 97 +/- 2% at 7 years. Doppler echocardiography revealed absent, trivial or mild aortic insufficiency in most patients; only 9 patients had moderate aortic insufficiency. CONCLUSIONS: Aortic valve sparing operations are feasible in most patients with ascending aorta and/or aortic root aneurysms who have normal or near normal aortic leaflets. The functional results of the repaired aortic valve are excellent, and the repair appears to be durable.

Adolescent↗
PubMed1999

The Toronto SPV bioprosthesis: clinical and hemodynamic results at 6 years.

BACKGROUND: The Toronto SPV (stentless porcine valve) bioprosthesis has been in use for aortic valve replacement since July 1991. Before its approval by the Food and Drug Administration, 635 patients were enrolled in a prospective observational clinical trial in eight centers. This report is an update on that trial. METHODS: There were 419 men and 216 women whose mean age was 66 years, range 33 to 93 years. In addition to aortic valve replacement, 264 patients also had coronary artery bypass, 9 had mitral valve repair, and 7 had replacement of the ascending aorta. The external diameter of most valves implanted was 25 mm or greater. Echocardiography has been done annually. The follow-up for this report was closed in September 1998 and mean follow-up was 2.7 years, range 0 to 6.3 years. RESULTS: There were 17 operative and 38 late deaths. Actuarial survival was 82.6% at 6 years. Freedom from morbid events at 6 years was 90% for cardiac-related deaths, 93.6% for all thromboembolic events, 98.6% for endocarditis, 98.2% for repeat aortic valve replacement, and 100% for primary tissue failure. Approximately 85% of patients have no aortic insufficiency, with no change in this proportion during the first 6 years of observation. The mean systolic gradient decreased during the first 6 months and remained unchanged over the years. It was approximately 5 mm Hg for all patients. Most patients (81%) are free from cardiac symptoms. CONCLUSIONS: This porcine bioprosthetic valve has provided excellent clinical and hemodynamic results after aortic valve replacement. Longer follow-up is needed to determine its durability and the potential benefits of its hemodynamic features.

Adult↗
PubMed1999

Histologic abnormalities of the ascending aorta and pulmonary trunk in patients with bicuspid aortic valve disease: clinical relevance to the ross procedure.

OBJECTIVE: Bicuspid aortic valve disease is often associated with dilation of the aortic root and ascending aorta. This study examines the histologic features of the ascending aorta and main pulmonary artery of patients with and without aortic valve disease. METHODS: Samples from ascending aorta and main pulmonary artery were obtained at the time of the operation from 20 patients with bicuspid aortic valve and 11 patients with tricuspid aortic valve disease. In addition, samples were also obtained from autopsy cases with normal aortic valve. The histologic changes were graded from 1 to 3 according to severity of degenerative changes. RESULTS: In the ascending aorta, the severity of cystic medial necrosis (P =.001), elastic fragmentation (P =.002), and changes in the smooth muscle cell orientation (P =.002) were significantly more severe in patients with bicuspid than in those with tricuspid aortic valve disease. In the pulmonary trunk specimens, those 3 histologic features were also significantly more severe in patients with bicuspid than those with tricuspid valves (P =.001, P =.01, and P =.04, respectively). Seventy-five percent of patients with bicuspid aortic valve disease had grade 3 degenerative changes, whereas only 14% of those patients with tricuspid aortic valve disease had similar degrees of degenerative changes. CONCLUSION: Patients with bicuspid aortic valve disease have more severe degenerative changes in the media of the ascending aorta and main pulmonary artery than patients with tricuspid aortic valve disease. These findings may explain root and ascending aortic dilation in patients with bicuspid aortic valve disease and pulmonary autograft dilation in certain patients after the Ross procedure.

Adult↗
PubMed1999

Structural valve deterioration in mitral replacement surgery: comparison of Carpentier-Edwards supra-annular porcine and perimount pericardial bioprostheses.

BACKGROUND: Bioprostheses preserved with glutaraldehyde, both porcine and pericardial, have been available as second-generation prostheses for valve replacement surgery. The performance with regard to structural valve deterioration with the Carpentier-Edwards supra-annular (CE-SAV) porcine bioprosthesis and the Carpentier-Edwards Perimount (CE-P) pericardial bioprosthesis (Baxter Healthcare Corp, Edwards Division, Santa Ana, Calif) was evaluated to determine whether there was a difference in mitral valve replacement. METHODS: The CE-SAV bioprosthesis was implanted in 1266 overall mitral valve replacements (isolated mitral, 1066; mitral in multiple, 200) and the CE-P bioprosthesis in 429 overall mitral valve replacements (isolated mitral, 328; mitral in multiple, 101). The mean age of the CE-SAV population was 64.2 +/- 12.2 years and that of the CE-P population, 60.7 +/- 11.7 years (P =.0001). For the study, structural valve deterioration was diagnosed at reoperation for explantation. RESULTS: The freedom from structural valve deterioration was evaluated to 10 years, and the freedom rates reported are at 10 years. For the overall mitral valve replacement groups, the actuarial freedom from deterioration was significant (P =.0001): CE-P > CE-SAV for 40 years or younger, 80% versus 60%; 41 to 50 years, 91% versus 61%; 51 to 60 years, 84% versus 69%; 61 to 70 years, 95% versus 75%. The older than 70-year group was 100% versus 92% (no significant difference). The actual freedom from structural valve deterioration also demonstrated the same pattern at 10 years: 40 years or younger, CE-P 82% versus CE-SAV 68%; 41 to 50 years, 92% versus 70%; 51 to 60 years, 90% versus 80%; 61 to 70 years, 97% versus 88%; and older than 70 years, 100% versus 97%. The independent risk factors of structural valve deterioration for the overall mitral valve replacement group were age and age groups and prosthesis type (CE-SAV > CE-P). The prosthesis type either in isolated replacement or in multiple replacement was not predictive of structural valve deterioration. The pathology of structural valve deterioration was different: 70% of CE-P failures were due to calcification and 57% of CE-SAV failures were due to combined calcification and leaflet tear. CONCLUSION: The actuarial and actual freedom from structural valve deterioration, diagnosed at reoperation, is greater at 10 years for CE-P than for CE-SAV bioprostheses. The mode of failure is different, and the cause remains obscure. Long-term evaluation is recommended, because the different modes of failure may alter the clinical performance by 15 and 20 years.

Adolescent↗
PubMed1999

The impact of age, coronary artery disease, and cardiac comorbidity on late survival after bioprosthetic aortic valve replacement.

OBJECTIVES: This study was designed to determine the effects of age, coronary artery disease and other cardiac comorbidities on late outcome following bioprosthetic aortic valve replacement. METHODS: Data were prospectively collected on 670 patients undergoing aortic valve replacement with the Hancock II bioprosthesis (Medtronic, Inc, Minneapolis, Minn) between 1982 and 1994. Mean patient age was 65 +/- 12 years (median, 68 years; range, 18-86 years). Follow-up was 99.7% complete at 69 +/- 40 months (median, 66 months; range, 0. 1-168 months). Survival and freedom from reoperation were evaluated univariately by Kaplan-Meier analysis and multivariably by Cox regression. RESULTS: After adjustment for gender, Cox regression analysis revealed that age of 65 years or older, left ventricular dysfunction, the presence of coronary artery disease, and advanced New York Heart Association functional classification were associated with a higher risk of late death. At 12 years, survival was significantly different by Kaplan-Meier analysis for both age younger than 65 years (71% +/- 4%) versus age 65 years or older (36% +/- 7%; P <.0001), left ventricular function grades 3 and 4 (26% +/- 13%) versus grades 1 and 2 (59% +/- 4%; P <.0001), no coronary artery disease (65% +/- 4%) versus coronary artery disease (35% +/- 8%; P <.0001), and functional class IV (33% +/- 9%) versus classes I to III (62% +/- 4%; P <.0001). Only 9 patients experienced primary tissue failure, all of whom were younger than 65 years of age. At 12 years, the freedom from primary tissue failure was 84% +/- 4% for those patients younger than 65 years of age, and 100% for those 65 years of age or older (P =.006). CONCLUSIONS: Long-term survival after aortic valve replacement is highly dependent on age, coronary artery disease, functional class, and left ventricular function, although bioprosthetic durability is dependent almost solely on age. Due to increased valve durability in patients who are 65 years of age or older, the Hancock II bioprosthesis may be an ideal aortic valve substitute in this age group. In patients who are younger than 65 years of age with advanced functional class, impaired left ventricular function, and coronary artery disease, this valve may also be used with a low probability of primary tissue failure. Patients without additional cardiac comorbidity may outlive their bioprosthetic valve, leading to reoperation.

Adult↗
PubMed1999

Stentless xenograft aortic valves.

Replacement of the diseased aortic valve represents one of the triumphs of cardiac surgery; however, the perfect valve substitute continues to elude surgeons after almost four decades of clinical experience. The characteristics of the ideal valve substitute include the following: central flow capacity, low transvalvular gradient, low thrombogenicity, durability, easy availability, resistance to infection, non-immunogenicity, and easy implantability. The pulmonary autograft first performed by Ross (Lancet 1967, 2:956-958) came closest to achieving these goals, but creates a double valve procedure for single valve disease. Aortic valve replacement (AVR) with homograft aortic valve was introduced by Ross in 1962 (Lancet 1962, 2:487) and Barratt-Boyes in 1964 (Thorax 1964, 19:131-150). Like the pulmonary autograft, homograft AVR results in an excellent hemodynamic outcome but suffers from limitations of graft availability, lack of durability, and difficulty with implantation. Mechanical valves and stented tissue valves allow "off the shelf" easy availability as well as easy implantability. These valves are unfortunately intrinsically obstructed to some extent because of the space occupied by the stent and sewing ring. Stent mounted tissue valves also continue to exhibit limited durability. Stentless xenograft aortic valves have been developed as a compromise between these ends of the valve spectrum to allow excellent hemodynamics and hopefully improved durability while allowing "off the shelf" availability in a variety of standard sizes. We examine the rationale for use of the stentless xenograft aortic valve, the clinical development of this valve, and the surgical techniques of implantation.

Animals↗
PubMed1999

Mitral valve replacement with preservation of the subvalvular apparatus.

The introduction of the Starr-Edwards valve allowed complete replacement of diseased left-sided heart valves. With improved cardiopulmonary bypass, myocardial protection, and surgical techniques the mortality rate from aortic valve replacement decreased substantially, whereas the mortality rate from mitral valve replacement remained high, largely because of low cardiac output syndrome. Increasing use of mitral valve repair techniques resulted in a marked decrease in short-term and long-term morbidity and mortality when treating patients with mitral regurgitation. Some believed that this resulted from maintenance of the mitral annular papillary muscle continuity during mitral valve repair. Subsequent experimental and clinical studies have validated the positive short-term and long-term effects of maintaining the integrity of the mitral valve subvalvular apparatus. This article considers the history of the clinical use of preservation of the subvalvular apparatus, the physiologic studies examining this concept, and the clinical data available on its use. It also examines the following: 1) mitral stenosis versus mitral regurgitation and the preservation of the subvalvular apparatus; 2) whether the anterior, posterior, or both areas of the subvalvular apparatus should be preserved; and 3) the surgical techniques for the preservation of the subvalvular apparatus and valve implantation.

Animals↗
PubMed1999

Morphologic findings in explanted Hancock II porcine bioprostheses.

BACKGROUND AND AIM OF THE STUDY: Heart valve substitutes have been in use for over 30 years. Bioprosthetic heart valves have many advantages, but unfortunately suffer tissue degeneration and calcification. Many approaches, such as antimineralization treatment to prevent or delay these changes, have been tried. We present the morphologic findings from a series of Hancock II (antimineralization-treated) porcine bioprostheses. METHODS: Forty-five Hancock II porcine valve bioprostheses (16 mitral, 29 aortic) surgically explanted between March 1991 and December 1995 at the Toronto Hospital were analyzed for morphologic findings and causes of failure. The prostheses were implanted in 36 adults (mean age 55+/-14.7 years, range: 27 to 75 years) and had been in place between one month and 11 years (mean 5.1+/-3.3 years). RESULTS: Structural valve deterioration (SVD) characterized by tissue degeneration, calcification, cusp tears and increased stiffness, was the single most significant finding and cause of failure, affecting 56% of valves. Some degree of calcification was seen in 55% of prostheses, with severe calcification (grade 3 or 4) in 18%. Aortic bioprostheses showed more severe and earlier calcification than mitral ones (p = 0.03). Compared with the standard Hancock valve, the low incidence of significant calcification suggests a beneficial protective effect of antimineralization treatment. Severe pannus (grade 3 or 4) was seen in 60% of these prostheses. The pattern of pannus growth differs between mitral and aortic sites; mitral prostheses showed pannus on the flow and non-flow surfaces, often associated with cusp tears, mitral regurgitation and mitral leaflet preservation. A similar degree of pannus on aortic prostheses was invariably present on the flow surface and extended onto the valve cusps, leading to changes in the orifice which may cause clinical aortic stenosis. Infective endocarditis was seen in 15 prostheses (five mitral, 10 aortic) from 11 patients, and comprised the second most important cause of prosthesis failure. The risk of recurrent endocarditis was particularly high in patients who had infective endocarditis before valve replacement, even at five and six years post implantation. CONCLUSIONS: SVD is the major finding in explanted Hancock II bioprostheses and is associated with cusp tears and calcification. The incidence of tissue calcification appears lower at the mitral site. These findings suggest that the antimineralization treatment had some beneficial effect. Pannus associated with prosthesis dysfunction at the mitral sites is a prominent finding and on the non-flow surface may be related to the native mitral valve-conserving procedure.

Adult↗