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Biomedical subjects

T E David

Publications and source records attributed to T E David.

At least 145 records · Page 8Linked to original sources
PubMed1986

Toward a better understanding of the etiology of left ventricular dysfunction after mitral valve replacement: an experimental study with possible clinical implications.

The relatively high morbidity and mortality of mitral valve replacement (MVR) appears to be related to an impairment in left ventricular (LV) function. This two-part investigation was designed to assess the effect of MVR on global LV function in an isolated heart preparation and to evaluate whether a mitral prosthesis with a flexible annulus would be of benefit. In Part I (14 pigs), the effects of each step in MVR were studied. Division of the chordae tendineae caused a severe deterioration in LV function (systolic pressure, 180 +/- 13 versus 120 +/- 10 mm Hg; p less than 0.05; developed pressure, 167 +/- 13 versus 108 +/- 11 mm Hg; p less than 0.05; first derivative of LV pressure [dP/dt], 2,630 +/- 300 versus 1,610 +/- 180 mm Hg/sec; p less than 0.05; balloon volume, 30 ml). Fixation of the mitral annulus prior to division of the chordae tendineae resulted in a small decrease (not significant) in LV function but had no effect after the chordae tendineae were divided. In Part II (10 pigs), two mitral annular prostheses were studied: a standard rigid prosthesis and a prosthesis of identical size but with a flexible annulus. LV function was better with the flexible than the rigid prosthesis (systolic pressure, 118 +/- 10 versus 89 +/- 5% control, p less than 0.02; developed pressure, 120 +/- 11 versus 87 +/- 5% control; p less than 0.02; dP/dt, 119 +/- 10 versus 85 +/- 4% control; p less than 0.02; balloon volume, 30 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Pheochromocytoma of the heart.

A patient with a pheochromocytoma involving the posterior wall of the left ventricle and the coronary sinus is reported. Complete surgical removal of the tumor was possible, although it caused a perioperative myocardial infarction. The literature regarding cardiac pheochromocytoma is reviewed.

Adult↗
PubMed1986

The effect of preservation of chordae tendineae on mitral valve replacement for postinfarction mitral regurgitation.

Fifty-one consecutive patients underwent mitral valve replacement for mitral regurgitation secondary to myocardial infarction. Fifteen patients were in cardiogenic shock when operated on, 22 were in NYHA functional class IV, and 14 were in class III. Mitral valve replacement with preservation of the chordae tendineae and papillary muscles was performed in 10 patients in cardiogenic shock and 22 patients who had elective surgery. Concomitant procedures included repair of left ventricular aneurysm in nine, tricuspid valve repair in three, aortic valve repair or replacement in four, and aortocoronary bypass in 44 patients. Twenty-six clinical, hemodynamic, angiographic, and operative variables were analyzed for statistical significance (univariate analysis) and then entered into a logistic regression analysis with operative and late mortality as end points. There were four operative deaths (8%). Only preoperative cardiogenic shock and mitral valve replacement with complete excision of the native valve were predictive of operative mortality. Actuarial survival at 4 years was 89 +/- 9% for patients with preserved chordae tendineae and 59 +/- 11% for patients with completely excised mitral valves. Only complete excision of the mitral valve and ejection fraction lower than 35% were predictive of late mortality. These data suggest that, although the papillary muscles are diseased in patients with mitral regurgitation secondary to myocardial infarction, it is important to preserve them and their chordae tendineae during mitral valve replacement.

Adult↗
PubMed1985

Thromboembolism in patients with aortic porcine bioprostheses.

Thromboembolism was prospectively studied in 215 patients who survived aortic valve replacement with porcine bioprostheses. All patients were anticoagulated with warfarin sodium during the first 3 postoperative months. Thereafter, 80 patients received aspirin (325 or 650 mg per day) and 135 received no antiplatelet or anticoagulant drugs. The two groups of patients were similar. Thromboembolic complications were carefully searched for during the follow-up interviews. Patients were removed from the study after a thromboembolic event unless there was no change in their management. The follow-up ranged from 6 to 80 months (mean, 36 months). The linearized thromboembolic rate in patients on a regimen of aspirin was 1.3% per patient-year and in patients not taking aspirin, 5.2% per patient-year (p less than 0.02). Replacement of the ascending aorta and patch enlargement of the aortic annulus with a Teflon graft were identified as significant risk factors for thromboembolism in patients with aortic porcine bioprostheses. These findings indicate that patients with aortic porcine bioprostheses should receive aspirin, especially if they also had replacement of the ascending aorta or patch enlargement of the aortic annulus with a Teflon graft.

Adolescent↗
PubMed1985

Combined cardiac and abdominal aortic surgery.

Patients with associated cardiac and abdominal aortic disease can undergo one or two separate operations for correction of both problems. The results of one (group A) and two separate operations (group B) were compared in 26 consecutive patients. There were 12 patients in group A and 14 patients in group B. Each patient underwent aortocoronary and aortofemoral bypass. In addition, three patients from group A and two patients from group B underwent cardiac valve surgery; three patients from group A and two patients from group B also had aortorenal bypass. There were no operative deaths and the complications were similar in both groups. The total amount of blood transfused in hospital, the length of stay in the operating room and intensive care unit, and the length of hospital stay were significantly shorter in group A. The average cost per patient in group A was approximately one-half of the average cost in group B. This combined approach for cardiac and abdominal aortic surgery is probably safe and is certainly cost effective.

Adult↗
PubMed1984

Mitral valve replacement for mitral regurgitation with and without preservation of chordae tendineae.

Left ventricular function was compared in 15 patients who had conventional mitral valve replacement (Group 1) and 12 patients who had replacement with preservation of chordae tendineae and papillary muscles (Group 2) for isolated chronic mitral regurgitation. Function was assessed by radionuclide ventriculography. The two groups were similar in terms of age, preoperative functional class, valve pathology, and preoperative left ventricular function. There was uniform intraoperative and postoperative management by a single surgeon. All patients received porcine bioprostheses. Left ventricular function was assessed 1 day before and 3 to 6 months after the operation. Left ventricular ejection fraction decreased from 0.55 +/- 0.09 to 0.48 +/- 0.14 in Group 1 (p less than 0.01) and did not change significantly in Group 2 (from 0.53 +/- 0.14 to 0.52 +/- 0.16). Left ventricular end-diastolic volume, end-systolic volume, and stroke volume indices decreased significantly in both groups. During maximal postoperative bicycle exercise with the patient supine, left ventricular ejection fraction and stroke volume index increased significantly in Group 2 only. Cardiac output increased in both groups during exercise, but this increase was due to increased heart rate in Group 1 and to increased heart rate and stroke volume in Group 2. These findings suggest that preservation of chordae tendineae and papillary muscles during mitral valve replacement for chronic mitral regurgitation has a beneficial effect on postoperative left ventricular function.

Adult↗
PubMed1983

Aortic valve replacement in adult patients with small aortic annuli.

Fifty-five patients with small aortic annuli underwent valve replacement either isolated or combined with other procedures. Patch enlargement of the aortic annulus in the area of the noncoronary sinus was used in 32 patients. The width of the patch was calculated by multiplying the desired increase in diameter by pi and adding 8 mm for suturing. The remaining 23 patients had aortic valve replacement with a prosthesis larger than the aortic annulus. The prosthesis was sutured in a supraannular position in the area corresponding to the noncoronary sinus. This slightly tilted position does not compromise function of Carpentier-Edwards or Björk-Shiley prostheses. Prosthetic gradients ranged from 0 to 18 mm Hg (9.2 +/- 3.9 mm Hg) in patients with patch enlargement of the aortic annulus and from 0 to 22 mm Hg (7.2 +/- 5.8 mm Hg) in patients with supraannular aortic prostheses. Although these techniques allow for insertion of prosthetic valves only one and two sizes larger than the aortic annulus, they appear to be satisfactory in most adult patients with a small aortic annulus.

Adult↗
PubMed1983

Cardiac valve surgery in patients with poor left ventricular function.

Of 316 patients who underwent operation for valvular heart disease at the Toronto Western Hospital, between January 1978 and December 1981, 41 (31 men, 10 women), ranging in age from 24 to 74 years, had severely impaired left ventricular function (ejection fraction less than 40% and left ventricular end-diastolic pressure more than 18 mm Hg). All 41 patients were in New York Heart Association (NYHA) class III or IV. Fourteen patients had disease of the aortic valve, 13 of the mitral valve and 14 of both aortic and mitral valves. Twenty-two patients also had serious coronary artery disease. The valve dysfunction was corrected in all patients by replacement or repair and all severe coronary artery stenoses were bypassed with saphenous vein grafts. There were three hospital deaths and five late deaths during a mean follow-up of 26 months (range from 6 to 48 months). All patients improved symptomatically by a least one functional NYHA class. The actuarial survival including operative deaths was 79%.

Adult↗
PubMed1983

The importance of the mitral apparatus in left ventricular function after correction of mitral regurgitation.

This study evaluates the possible role of the mitral apparatus in left ventricular function after correction of chronic mitral regurgitation. Seventeen patients underwent complete preoperative and early postoperative heart catheterization. Six patients underwent conventional mitral valve replacement (group 1), six mitral valve replacement with preservation of chordae tendineae and papillary muscles (group 2), and five mitral valvuloplasty (group 3). There was no statistically significant difference among the three groups for any hemodynamic parameter as compared before surgery by analysis of variance. After correction of mitral regurgitation the increase in cardiac index was similar for all three groups. Left ventricular end-diastolic volume did not decrease significantly in group 1 (p = NS), but it did in groups 2 and 3 (p less than .005 for both). Left ventricular end-systolic volume increased in group 1 (p less than .025) and decreased in groups 2 and 3 (p less than .01 and .005, respectively). Ejection fraction decreased in group 1 (p less than .005) and did not change in groups 2 or 3 (p = NS). Left ventricular end-diastolic pressure increased in group 1 (p less than .005) and decreased in groups 2 and 3 (p less than .01 for both). These findings suggest that continuity between mitral anulus and left ventricular wall through leaflets, chordae tendineae, and papillary muscles plays a role in left ventricular function after correction of the chronic mitral regurgitation.

Adult↗
PubMed1982

Rapidly progressive vegetative endocarditis.

Echocardiography has become a valuable tool in visualizing and localizing vegetations in patients with bacterial endocarditis. Since the natural course of vegetative lesions remains poorly understood, we report a case of a rapidly progressive vegetative lesion in a patient with staphylococcal endocarditis. Although the significance of this observation will require a larger experience, it may represent an accelerated form of disease necessitating surgical management.

Adult↗
PubMed1981

Excessive requirement for heparin during cardiac surgery.

A case of excessive heparin requirement during cardiopulmonary bypass is reported. A patient with sepsis secondary to a myocardial abscess require 13.5 mg x kg-1 of heparin to increase his activated coagulation time to a therapeutic level. This phenomenon might be due to individual variability, lupus vasculitis, septicaemia, repeated thromboembolic phenomenon with hypercoagulable state, or chronic disseminated intravascular coagulation with partial antithrombin deficiency.

Aged↗
PubMed1981

Long-term results following coronary bypass operation. Importance of preoperative actors and complete revascularization.

The initial 102 patients who underwent aorta-coronary bypass grafting between 1969 and 1971 were followed for a mean of 96 months (minimum follow-up 7 years). Preoperative variables predictive of survival at 5 years were stability of angina, previous heart failure, and left ventricular function. Stability of angina, previous heart failure, previous myocardial infarction, and smoking were important predictors of symptomatic status at 5 years. At operation, 62 patients had anatomic or technically complete revascularization, whereas 40 had incomplete revascularization. There was a significantly improved survival rate in those patients who were completely revascularized. The 5 year survival rate was 84% for completely revascularized patients compared to 96% for incompletely revascularized patient (p less than 0.02). This improvement in survival was continued to 9 years. There was also a significant improvement in asymptomatic status of the completely revascularized patients compared to the incompletely revascularized patients. At 2 years, 75% of the completely revascularized subjects were asymptomatic compared to 45% of the incompletely revascularized patients. However, this difference disappeared after 5 years. Thus complete myocardial revascularization is superior to incomplete revascularization in terms of survival and asymptomatic state. Preoperative variables may be useful in predicting postoperative results.

Actuarial Analysis↗
PubMed1981

Is it important to preserve the chordae tendinae and papillary muscles during mitral valve replacement?

To evaluate the importance of preserving chordae tendinae and papillary muscles to left ventricular function after mitral valve replacement, 12 dogs had Carpentier-Edwards or Björk-Shiley mitral valves inserted. Cardiopulmonary bypass, systemic hypothermia at 25 degrees C and cold cardioplegia were used. The period of anoxic arrest was 30 minutes. In six dogs, mitral valve replacement was performed after complete excision of the mitral valve. In the other six dogs the anterior leaflet was partially excised but all chordae tendinae and papillary muscles were left intact. Hemodynamic measurements, including left ventricular function following volume loading, were made preoperatively and postoperatively. Left ventricular angiograms were obtained postoperatively in all dogs. Preoperatively there was no significant difference in the left ventricular function curves in the two groups, but postoperatively the curves showed significant differences. In the group with preserved chordae tendinae, left ventricular function improved with volume loading to a left ventricular end-diastolic pressure of 20 mm Hg while in the group with divided chordae tendinae, function improved more slowly and ceased to improve after loading to an end-diastolic pressure of 15 mm Hg. The mean left ventricular ejection fraction following mitral valve replacement with preserved papillary muscles was 0.62 +/- 0.01 and with divided papillary muscles was 0.45 +/- 0.05 (P less than 0.05). The authors conclude that it is important to preserve chordae tendinae and papillary muscles when carrying out mitral valve replacement.

Animals↗
PubMed1980

Detection of entrapped intracardiac air with intraoperative echocardiography.

Embolization of entrapped intracardiac air represents a significant risk to the patient undergoing open heart surgery. To date, there have been no menas available to ensure that the heart is free of air prior to restoration of the circulation. To assess whether M mode echocardiography can accurately detect intracardiac air, we studied 10 dogs during cardiopulmonary bypass. Randomly, air was or was not injected into the left ventricular cavity of the fibrillating heart. Intracardiac air could be recognized by the presence of a stippled granular pattern, or a loss of the discrete linear echoes or decreased far field echoes, or any combination of these three. In all, 131 random observations were made. When 1.0 cc of air was injected, sensitivity and specificity were both 100 percent, but when 0.2 cc was injected, sensitivity and specificity decreased to 86 and 58 percent, respectively. thus, M mode echocardiography appears to provide a sensitive and specific tool for detecting intracardiac air.

Animals↗
PubMed1980

Surgical procedures involving cardiopulmonary bypass in patients aged 70 or older.

Cardiac surgery was performed in 27 patients whose ages ranged from 70 to 78 years (mean, 72). In 17 of these patients, the operation was coronary artery bypass grafting without other procedures. There were 3 operative deaths (17.6 percent) but no late deaths during a mean follow-up period of 14 months, and all the 14 surviving patients were improved symptomatically. In the other 10 of the 27 patients, the operation was valve replacement. There was no operative mortality among the 6 aortic valve patients and 1 operative death among the 4 mitral valve patients; the corresponding late deaths were 2 and 1, respectively, during a mean follow-up period of 41.3 months. Improvements in operative management and improved criteria for the selection of patients should afford benefits and risks for elderly cardiac patients similar to those for younger cardiac patients.

Aged↗
PubMed1980

Surgical treatment of annuloaortic ectasia.

Twenty-two patients with annuloaortic ectasia (an aneurysm of the ascending aorta and aortic valve incompetence) due to cystic medionecrosis underwent surgical repair between 1967 and 1979. Twelve patients had Marfan's syndrome and 4 had a forme fruste. The use of a valved conduit and improved techniques of myocardial protection have reduced the perioperative risks and may improve the survival of these patients. Between July 1, 1967 and June 30, 1978, 12 patients had supracoronary repair of the aneurysm and replacement of the aortic valve (group 1); the mortality was 17% (2 of 12). Between July 1, 1978 and Aug. 31, 1979, 10 patients underwent insertion of a valved conduit with implantation of the coronary arteries (modified Bentall procedure, group 2); the operative mortality was 10%. In five group 1 patients (42%) and two group 2 patients (20%) technical problems resulted in bleeding in the early postoperative period. Evidence of a recurrent aneurysm in the diseased segment of the proximal aorta developed in 2 of the 10 group 1 survivors, at 2 and 4 years after operation, respectively. Use of the modified Bentall procedure and cold potassium cardioplegia reduced operative complications from 58% (7 of 12 in group 1) to 20% (2 of 10 in group 2). Because of the low risk of the current procedure and the high risk associated with its natural history, operative intervention should be considered for asymptomatic patients with annuloaortic ectasia.

Adolescent↗
PubMed1978

Profundoplasty for limb salvage.

Profundoplasty was performed in 26 legs because of rest pain or gangrene; previous arterial reconstruction had been done in 12 of them. In 16 limbs the popliteotibial segment was patent; profundoplasty was successful in each case. In 10 limbs the popliteotibial segment was occluded, and profundoplasty failed in one instance. One patient died. The authors believe that re-establishing blood flow and pressure to the deep femoral artery, especially to the descending branch of the lateral circumflex artery and the distal part of the deep femoral artery can effectively improve the condition of ischemic legs.

Adult↗