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Biomedical subjects

T E David

Publications and source records attributed to T E David.

At least 91 records · Page 5Linked to original sources
PubMed1995

Is body size the cause for poor outcomes of coronary artery bypass operations in women?

Although small body size and coronary artery diameter are recognized as major contributors to the increased risk of coronary artery bypass grafting in women, few studies have established the independent influence of body size and gender on outcome. We studied 7025 consecutive patients (5694 men, 1331 women) undergoing isolated coronary artery bypass grafting between 1990 and 1994. Women were older, had higher preoperative prevalences of urgent operation because of unstable angina, diabetes, peripheral vascular disease, hypertension, and single-vessel coronary artery disease (p < 0.0001), and a lower prevalence of left ventricular ejection fraction 40% or less (p < 0.0001). The prevalences of operative mortality (men, 1.8%; women, 3.5%), low-output syndrome (men, 6.6%; women, 14.8%), and myocardial infarction (men, 2.8%; women, 5.5%) were higher in women (p < 0.0001). Patients were divided into quartiles for body surface area, weight, height, and body mass index. For both men and women, there was no difference in operative mortality between the highest and lowest quartiles of body size. Women, however, had a higher prevalence of operative mortality than men in the lower quartiles of body surface area, height, and weight and in the higher quartiles of body mass index. Among men, the prevalence of low-output syndrome increased (p < 0.0001) with decreasing body surface area, weight, and body mass index, suggesting that body size did influence the prevalence of low-output syndrome. However, women had a higher prevalence of low-output syndrome than men in every category and quartile of body size (p < 0.0001). Multivariable analysis identified gender as a significant determinant of operative mortality (odds ratio 1.83, 95% confidence interval 1.27 to 2.64) and low-output syndrome (odds ratio 2.52, 95% confidence interval 2.05 to 3.11). When multivariable adjustments were made for body size and preoperative risk factors, gender remained a predictor of both operative mortality and low-output syndrome. Multivariable assessment of risk for men and women separately identified that urgent operation was a predictor of operative mortality (odds ratio 2.52, 95% confidence interval 1.32 to 5.61) and low-output syndrome (odds ratio 1.57, 95% confidence interval 1.14 to 2.17) in women but not men. In conclusion, the increased risk of coronary artery bypass grafting in women may be explained in part by dramatic differences in preoperative risk factors between men and women. In both men and women, small body size did not increase the risk of operative mortality, but may have contributed to the risk of low-output syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1995

Repair of the aortic valve in patients with aortic insufficiency and aortic root aneurysm.

Patients with aneurysms of the ascending aorta or aortic root frequently have aortic insufficiency despite normal aortic leaflets. The aortic valve dysfunction is caused by dilatation of the sinotubular junction, distortion or dilatation of the sinuses of Valsalva, annuloaortic ectasia, or a combination of these problems. In the case of annuloaortic ectasia, reconstruction of the aortic root is performed by reimplanting the aortic valve in a tubular Dacron graft (reimplantation). In the case of mild or no annuloaortic ectasia, reconstruction of the aortic root is performed by correcting the dilated sinotubular junction and replacement of the aortic sinuses if they are also dilated with an appropriately tailored Dacron graft (remodeling). From July 1989 to March 1994, 45 patients have had either reimplantation of the aortic valve (19 patients) or remodeling of the aortic root (26 patients). Fourteen patients had Marfan's syndrome, 11 had acute and five had chronic type A aortic dissection, and nine also had transverse arch aneurysm. There were two operative deaths, both in the remodeling group. One patient who had reimplantation needed composite replacement of the aortic valve and ascending aorta because of persistent aortic insufficiency after the repair. A young patient with Marfan's syndrome had progressive aortic valve dysfunction during a growth spurt and had aortic valve replacement 2 years after the initial operation. No other valve-related complication has occurred. The remaining 41 patients have only mild or no aortic insufficiency, and the repair remains stable from 1 to 58 months, mean 18 months. These two types of aortic valve reconstruction have provided excellent clinical results in carefully selected adult patients.

Adult↗
PubMed1995

Follow up of patients after valvular surgery: mail vs. telephone.

A study was undertaken to compare the results of patient follow up done by mail and by telephone. Using valve follow up questionnaires recently received by mail, 100 patients were randomly selected from this group for further follow up by telephone. Interviews were conducted while blinded to the mail response. Patients were questioned as to their functional status (NYHA), improvement as a result of surgery (IMP), incidence of reoperation (REOP) or bacterial endocarditis (SBE) and thromboembolic complications (TE). They were also asked whether they would prefer future follow up by mail or telephone. Analysis using the kappa coefficient and McNemar's test revealed a difference (p < 0.001) in NYHA when comparing mail and telephone responses but no difference in either IMP or TE. There was no incidence of REOP or SBE. Sixty-six percent of patients had no preference in type of future follow up and of the remaining 33%, two-thirds preferred to be contacted by phone. It appears that NYHA is significantly overestimated by the patient whereas the two methods of follow up are comparable when assessing IMP and TE. It should be noted, however, that patients seem to have difficulty in identifying the occurrence of TE and in differentiating between stroke and TIA.

Activities of Daily Living↗
PubMed1995

The surgical treatment of patients with prosthetic valve endocarditis.

Prosthetic valve endocarditis is associated with high mortality and morbidity. Although antibiotics alone may sterilize an infected prosthetic valve, adjunctive surgical therapy is often necessary. Depending on the virulence of the offending microorganism, the type of prosthetic valve and the site where it was implanted, the infection spreads into paravalvular structures, producing abscess. Systemic embolization of infected material may cause metastatic abscess. Thus, timing of surgery in these patients is crucial to optimize clinical results. An aggressive approach is justifiable in most patients with prosthetic valve endocarditis. It is believed that radical resection of all infected material and reconstruction of the heart and annuli with fresh autologous or glutaraldehyde-fixed bovine pericardium offer the best chance to eradicate the infection. Prolonged antibiotic therapy is also necessary in these patients. In the author's personal experience with 45 patients with prosthetic valve endocarditis, the infection was limited to the valve in 10 patients and had extended into the surrounding tissues in 35. The operative mortality rate was 13%. The actuarial survival at 5 years was 61% +/- 5%. These results support the premise that radical resection of all infected materials offers a good chance for curing prosthetic valve endocarditis.

Abscess↗
PubMed1995

Left ventricular function after mitral valve surgery.

This study examined the effects of various operative procedures on the mitral valve of patients with mitral regurgitation due to degenerative disease of the mitral valve. A randomized clinical trial on the type of annuloplasty ring used at surgery revealed that early postoperative left ventricular systolic function was better in patients who had a flexible ring than in patients who had a rigid ring. Two years after surgery there were no differences between these groups and most patients were found to have fairly normal left ventricular function. The long term results of mitral valve repair in 184 patients revealed a 10-year actuarial survival of 86% +/- 6%. A randomized trial on the effect of preservation of chordae tendineae during mitral valve replacement revealed that the beneficial effect of this procedure on left ventricular function is a lasting one; five years after surgery patients who had mitral valve replacement with preservation of the chordae tendineae have better exercise capacity, and better left ventricular systolic function and performance. The long term results of mitral valve replacement in 154 patients revealed a 10-year actuarial survival of 69% +/- 5%. Logistic regression analysis indicated that age greater than 65 years and complete excision of the native mitral valve were predictors of late mortality. Of those patients, 70 had had chordal preservation during surgery and 84 did not. These two subgroups were remarkably similar preoperatively, but the 10-year actuarial survival was 80% +/- 6% for patients who had chordal preservation and 63% +/- 6% for those who did not. The mitral valve should be repaired whenever possible; if replacement is necessary it should be performed with preservation of the chordae tendineae.

Actuarial Analysis↗
PubMed1995

Operative management of postinfarction ventricular septal defect.

Postinfarction ventricular septal defect (VSD) remains a surgical challenge because it is technically difficult to reconstruct the septum during the acute phase of a transmural myocardial infarction, and it is a relatively uncommon operative procedure. Conservative treatment is not advisable because most patients develop congestive heart failure and cardiogenic shock, and die. Surgery should be performed soon after the diagnosis in most patients. Hemodynamically compromised patients should have intra-aortic balloon pump, vasodilators, inotropes and, if necessary, assisted ventilation. Coronary angiography should be performed before surgery because approximately two-thirds of the patients have multivessel disease, and concomitant revascularization is important to improve surgical outcome. Classical operative techniques included infarctectomy and reconstruction of the ventricular septum and free walls of the heart with Dacron patches. Since 1987, we have used a novel operative technique, whereby the left ventricle is largely excluded from the infarcted muscle using a bovine pericardial patch sutured to its healthy endocardium. Because right ventricular dysfunction has been identified as an important determinant in the outcome of these patients, we believe that this newer procedure is preferable to previous ones because it leaves the right ventricle undisturbed. From 1980 to 1994, we treated 67 patients with postinfarction VSD using operative techniques that evolved from infarctectomy and reconstruction of the septum with Dacron patches to pericardial patch exclusion of the left ventricle. Thirty-eight patients were in cardiogenic shock when operated on. The overall operative mortality rate was 13.4% and the 10-year actuarial survival rate was 62% +/- 6%. We believe that repair of postinfarction septal rupture by the infarct exclusion technique has improved the outcome of these patients, particularly in those with posterior ventricular septal defect and cardiogenic shock.

Aged↗
PubMed1994

Infective endocarditis in patients who had replacement of the aortic root.

In 12 patients who had had composite replacement of the aortic valve and ascending aorta, infective endocarditis developed 2 months to 17 years after operation. Six patients had mechanical valves and 6 had biological ones (four homograft and two porcine valves). All patients needed operation because of shock, heart failure, persistent sepsis in spite of adequate antibiotic therapy, or the development of a paravalvular false aneurysm. The predominant microorganism was Staphylococcus. All 6 patients who had mechanical valves were found to have an abscess in the junction between the aortic annulus and the prosthesis; in patients who had biological valves the infection was limited to the leaflets in 3 (one homograft and two porcine valves) and leaflets and annulus abscess in 3 (three homograft valves). Operation consisted of radical resection of tissues suspected of being infected and reconstruction of the left ventricular outflow tract and of the surrounding structures with glutaraldehyde-fixed bovine pericardium. The aortic valve and ascending aorta were replaced with a new valved conduit. An aortic homograft was used in only 1 patient. There was only one operative death due to right ventricular infarction but most patients experienced serious postoperative complications. Operative survivors were followed up from 3 to 156 months (mean, 42 months). One patient died 35 months postoperatively due to bleeding complications of anticoagulation; 1 patient suffered a cardiac arrest at home 2 months after operation, sustained permanent cerebral damage, and died 4 months later. The remaining patients are asymptomatic from the cardiovascular viewpoint.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Aortic valve repair in patients with Marfan syndrome and ascending aorta aneurysms due to degenerative disease.

Patients with Marfan syndrome may require aortic surgery because of aortic insufficiency, aortic root aneurysm, ascending aortic aneurysm, or acute type A aortic dissection. The aortic valve leaflets are often overstretched and the fibrosa layer is damaged in many patients, particularly in those with all the stigmata of Marfan syndrome. However, in some patients the leaflets are normal or only minimally stretched in spite of aortic insufficiency. In these patients the aortic valve can be satisfactorily repaired. When significant annuloaortic ectasia is present, the reconstructive procedure consists of excising all three aortic sinuses and reimplanting the aortic valve inside a Dacron graft. If the annuloaortic ectasia is mild and the principal problem is loss of the sinotubular junction because of aneurysmal dilatation of the sinuses of Valsalva, aortic valve repair is accomplished by replacing one, two, or all three aortic sinuses with a properly tailored Dacron graft. The first type of aortic valve repair has been performed in 18 patients with one early and one late failure. The other 16 patients remained well from 3 to 50 months. The second type of aortic valve repair has been performed in 15 patients during the past 3 years without any failure and all patients remain well. Therefore, in selected patients with aortic insufficiency due to aortic root and/or ascending aorta aneurysm secondary to degenerative disease, the aortic valve can be repaired with satisfactory results.

Adolescent↗
PubMed1994

Papillary muscle-annular continuity: is it important?

The interactions between the mitral valve and left ventricle are complex and not yet completely understood. However, continuity between the papillary muscles and the mitral annulus is probably the most important factor in this relationship because severance of the chordae tendineae in experimental animals causes a significant drop in left ventricular systolic function as assessed by load independent parameters. This deterioration in ventricular function is even more marked in dilated hearts due to chronic mitral regurgitation. There is strong clinical evidence that maintenance of papillary muscle-annular continuity during mitral valve surgery is beneficial to left ventricular function and clinical outcome. That is one of the reasons why the mitral valve should be repaired rather than replaced in patients who need mitral valve surgery. If replacement is necessary, the chordae tendineae should be preserved. If preservation of chordae tendineae is difficult because of calcification, fibrosis, or for other reasons it is possible to resuspend the papillary muscle with expanded tetrafluoroethylene sutures. Preservation of chordae tendineae during mitral valve replacement is also important because it prevents spontaneous rupture of the posterior wall of the left ventricle, a rare but dreaded complication of this type of surgery.

Animals↗
PubMed1994

Techniques and results of mitral valve repair for ischemic mitral regurgitation.

Mitral regurgitation (MR) may start during the acute phase of myocardial infarction and it may increase, decrease, or remain unchanged as the necrotic muscle is replaced by fibrous tissue and remodeling of the ventricle takes place. Acute infarction can cause MR because of rupture of papillary muscle (PM) head or dysfunction of the PM and underlying ventricular wall. When MR is due to rupture of a single PM head and the surrounding muscle is not extensively infarcted, it is possible to suture the PM head in place with pledget sutures or to use other techniques of repair of flair leaflets such as chordal transfer or chordal replacement. When MR is due to extensive necrosis of the PM and the ventricular wall, it is safer to replace the mitral valve with preservation of the chordae tendineae. Correction of MR by means of valve repair in patients with healed myocardial infarction is frequently possible when the cause of MR is determined by Doppler echocardiography. The most common cause of MR is incomplete closure of the mitral valve due to apical displacement of the PM. Prolapse of the leaflets is rare in patients with healed myocardial infarction. Mitral annuloplasty decreases or abolishes MR in most cases when lack of coaptation of the leaflets is the problem. Transient ischemia can also cause MR. Successful myocardial revascularization either by angioplasty or coronary artery bypass often cures episodic ischemic MR.

Coronary Disease↗
PubMed1994

Stentless porcine bioprosthesis for aortic valve replacement.

We report herein our experience with the Toronto Stentless Porcine Valve (Toronto SPV, manufactured by St. Jude Medical Inc., Minneapolis, MN, USA) for aortic valve replacement (AVR). To date 146 SPV valves have been implanted, 29 in an initial clinical trial (from October 1987 to April 1987) and 117 in the current FDA trial (September 1991 to January 1994). In the current trial the majority of patients were male (76%), aortic stenosis was the dominant lesion (73%) and 68% of the patients received a valve size 27 mm or greater. The mean age was 61.3 +/- 12.0 years. For the entire group there has been no hospital death and no patient has required a pacemaker. Perioperative complications were myocardial infarction in three patients and suspect subacute bacterial endocarditis (medically treated) in three patients. There have been two late deaths (2%), two patients have had transient ischemic attacks (2%), and one patient suffered stroke with complete neurological recovery (1%). To date there has been no case of primary valve failure. Echocardiographic assessment of the SPV valve has demonstrated excellent effective valve orifice areas with very low transvalvular gradients and 95% of the patients had either 0 or 1+ insufficiency. These results are encouraging and justify the continued use of this valve in clinical trials. Further follow-up is required to determine its durability.

Adult↗
PubMed1994

Late hemodynamic effects of the preserved papillary muscles during mitral valve replacement.

BACKGROUND: The late hemodynamic effects of preserving the papillary muscles during mitral valve replacement have not been evaluated. METHODS AND RESULTS: Sixteen patients who had chronic mitral regurgitation due to myxomatous degeneration were randomized to preservation (Pres group, n = 8) or no preservation (No Pres group, n = 8) of the chordae tendineae and papillary muscles during mitral valve replacement. Rest and exercise nuclear ventriculograms were performed early (3 months) and late (5 years) after surgery. Early after surgery, the No Pres group had lower ejection fractions and stroke work indexes (P < .05 by repeated-measures [rm] ANOVA) than the Pres group did at similar end-diastolic volume indexes. The No Pres group had similar cardiac indexes after exercise because heart rate increased (P < .005 by rm ANOVA). Late after surgery, ejection fraction was greater at similar end-diastolic volume indexes (P < .005 by rm ANCOVA), and preload recruitable stroke work indexes (P < .001 by rm ANCOVA) were better in the Pres group. CONCLUSIONS: Preserving chordal attachments enhanced the late hemodynamic recovery after mitral valve replacement for mitral regurgitation.

Chordae Tendineae↗
PubMed1994

Aortic valve replacement with a stentless porcine aortic valve. A six-year experience.

A stentless porcine aortic valve was used for aortic valve replacement in 123 patients from 1987 to 1993. The mean age of 86 men and 37 women was 61 +/- 12 years. Most patients had aortic stenosis; one-third had coronary artery disease and six had mitral valve disease. The stentless valve was secured in the subcoronary position by the same technique used for a freehand aortic valve homograft. The size of valve was based largely on the diameter of the sinotubular junction of the aortic root. The mean valve size was 26.5 mm (range 19 to 29 mm) and 87% were 25 mm or larger. Two operative deaths occurred, one the result of myocardial infarction and the other the result of infective endocarditis. Patients have been followed up from 3 to 77 months, mean 22 months. Three late deaths, none related to the valve, have occurred. The actuarial survival at 6 years was 91% +/- 4%. Four transient cerebral ischemic events have occurred, but two patients had extracranial cerebrovascular disease. One patient had endocarditis late in the postoperative period and required reoperation. All patients had Doppler echocardiographic studies before discharge from the hospital, 3 to 6 months later and annually. Only 15 patients have aortic insufficiency, trivial in 6 and mild in 9. The peak and mean systolic gradients decreased significantly during the first 3 to 6 months after implantation (p < 0.001), and the effective valve areas increased significantly during this time interval (p < 0.001). This improvement in valve hemodynamics is believed to be due to remodeling of the aortic root and regression of left ventricular hypertrophy. The results of aortic valve replacement with this stentless bioprosthesis have been excellent and justify its continued use in older patients.

Adult↗
PubMed1994

Aortic root and valve relationships. Impact on surgical repair.

A surgical procedure has recently been described for patients with aortic incompetence caused by annular dilation, but with normal aortic leaflets. The dilated aortic root is replaced with a Dacron graft, and the native aortic valve is resuspended within the graft. Matching the size and shape of the graft to the size of the leaflets may have significant effects on valve closure and leaflet stress and thus on the longevity of the repair. To define the relationship of native aortic root structure to leaflet size, we morphologically examined normal human aortic roots (n = 10) and valve leaflets and applied mathematic analyses to the results. Our data show that the root has a consistent shape with varying size and that there is a definable mathematic relationship between root diameter and clinically measurable leaflet dimensions. We derived an equation that allows calculation of the appropriate diameter of the root at the sinus of Valsalva level from leaflet heights and perimeters. The diameter of the graft at the sinotubular junction and base should follow the relationship of the normalized root dimensions, either by tailoring of the graft or by new graft design. The current data imply that the graft should incorporate sinuses for proper valve closure and for sharing stress with the leaflets. Application of these results will allow prosthetic graft design to more closely resemble the native aorta. These new grafts should improve physiologic function of the valve, reduce leaflet stress, and increase the durability of the repair.

Adolescent↗
PubMed1993

Late results of mitral valve repair for mitral regurgitation due to degenerative disease.

From June 1981 to August 1992, 184 patients with mitral regurgitation due to degenerative disease underwent mitral valve repair. The mean age was 57 years, and 74% were men. One-third of the patients were in atrial fibrillation, and 71% were in New York Heart Association classes III and IV. The mitral regurgitation was due to prolapse of the posterior leaflet in 97 patients (53%), prolapse of the anterior leaflet in 42 (23%), and prolapse of both leaflets in 45 (24%). The degree of myxomatous changes was assessed intraoperatively as mild in 125 patients (68%), moderate in 27 (15%), and severe in 32 (17%). Mitral valve repair was accomplished largely by techniques described by Carpentier. Ring annuloplasty was performed in 160 patients (66 with Carpentier ring and 94 with Duran ring). There was one operative death, and 5 patients experienced life-threatening complications. Patients were followed up from 5 to 132 months (mean, 41 months). The actuarial survival at 8 years was 88% +/- 4%. The freedom from stroke at 8 years was 94% +/- 2%, and the freedom from transient ischemic attacks was 86% +/- 6%. Age greater than 60 years was the only factor associated with higher risk of thromboembolic complications by logistic regression analysis. The actuarial freedom from reoperation at 8 years was 95% +/- 2%. Advanced myxomatous changes in the leaflets of the mitral valve was the only significant factor associated with a higher risk of reoperation. Most patients were in New York Heart Association class I at the last follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Heart valve surgery.

Progress in valve repair and replacement continued over the past year. Aortic valve repair for aortic insufficiency appears promising, and aortic decalcification may still be a useful alternative in certain cases of aortic stenosis. Mitral valve repair, well accepted for myxomatous valves, presents a challenge in ischemic disease. Balloon mitral valvotomy offers significant short-term hemodynamic improvement, but needs to be properly compared with surgical treatment of mitral stenosis. Although aortic valve replacement with homografts and pulmonary autografts yields excellent results, enthusiasm for the stentless porcine xenograft is increasing. Clinical results reported for the Carpentier-Edwards pericardial valve (Baxter Healthcare Corp., Edwards Div., Santa Ana, CA) and the Bjork-Shiley monostrut valve (Shiley Inc., Irvine, CA) are excellent. Acute endocarditis continues to be a challenging problem but early aggressive debridement appears to offer patients the best chance of cure, regardless of what valve replacement is used.

Aortic Valve↗