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Biomedical subjects

L H Cohn

Publications and source records attributed to L H Cohn.

At least 19 recordsLinked to original sources
PubMed1992

Surgical treatment of adult atrial septal defect: early and long-term results.

OBJECTIVES: The purpose of this study is to determine the early and late results of the surgical repair of atrial septal defect in adults. BACKGROUND: Progressively limiting, untreated atrial septal defect can lead to the early death of middle-aged adults. Recently it has been suggested that the closure of atrial septal defects might be accomplished with interventional cardiac techniques. Although the long-term results of the transcatheter closure are as yet unknown, the outcome of surgical therapy has been shown to be beneficial for almost 40 years. METHODS: Between 1971 and 1991, 166 consecutive patients underwent surgical repair of a secundum or sinus venosus atrial septal defect, or both, at the Brigham and Women's Hospital, Boston. There were 120 women and 46 men in this group; the mean age was 44 years and 58 (35%) of the patients were > or = 50 years old. The average pulmonary to systemic flow ratio was 3.0, and 57 patients had a peak systolic pulmonary artery pressure > 30 mm Hg. RESULTS: There were two operative deaths (early mortality rate 1.2%), and 13% of the patients had a perioperative complication. One hundred fifty-three of the 164 survivors were followed up for a mean of 90 months (range 2 to 247). There were eight late deaths (late mortality rate 4.9%) and a late morbidity rate of 12.4% (in most cases due to arrhythmias). The 5- and 10-year survival rates are 98% and 94%, respectively, and the probability of event-free survival (with no morbidity or mortality) at 5 years is 97% and at 10 years is 92%. CONCLUSIONS: The results indicate that the surgical correction of atrial septal defect in adults is safe and efficacious as confirmed by 20 years of follow-up.

Adult↗
PubMed1992

Long-term follow-up of patients undergoing myotomy/myectomy for obstructive hypertrophic cardiomyopathy.

The long-term results of patients undergoing myotomy/myectomy of the ventricular septum for obstructive hypertrophic cardiomyopathy are documented in 31 patients (15 women, 16 men, age range 21 to 80 years [mean 55]) with mean New York Heart Association functional class III to IV congestive heart failure, who underwent radical myotomy/myectomy at the Brigham and Women's Hospital from 1972 to 1991. Preoperative gradients by catheterization or echocardiography ranged from 26 to 240 mm Hg (average 96). There were no operative deaths. Two patients developed early postoperative complete heart block requiring a transvenous pacemaker. Clinical follow-up was 1 to 14 years (mean 6.5). All surviving patients were restudied by echocardiography and clinical examination. The mean postoperative functional class was II. Postoperative gradients ranged from 0 to 30 mm Hg (mean 4.5) (p less than 0.001 compared with preoperative values). There were 5 late deaths (low cardiac output in 2, stroke in 2, and acute respiratory failure in 1); 4 of 5 deaths occurred in patients with concomitant coronary artery disease. Survival at 10 years was 86 +/- 9%. There were no reoperations for subaortic obstruction.

Cardiomyopathy, Hypertrophic↗
PubMed1992

Combined carotid and coronary revascularization: the preferred approach to the severe vasculopath.

The timing of carotid endarterectomy (CEA) and coronary revascularization (CABG) for concomitant disease is controversial. Results of combined CEA/CABG in 127 patients (age range, 46 to 82 years; mean age, 65 years; 61% male) from 1978 to 1991 were reviewed. Ninety-five patients (75%) were in New York Heart Association functional class III or IV, 48 (38%) had left main coronary artery disease, and 32 (28%) had depressed ejection fraction ( < 0.50). Forty (32%) had asymptomatic bruits, 61 (48%) transient ischemic attacks, and 26 (20%) prior strokes. Seventy-five (59%) had bilateral carotid stenosis, including 20 (16%) with contralateral occlusions. Perioperative mortality was 7 of 127 (5.5%), and all deaths were cardiac related. Myocardial infarctions occurred in 6 of 127 patients (4.7%) and were nonfatal in 3 (2.3%). Permanent strokes occurred in 7 of 127 (5.5%) and were ipsilateral in 5 (3.9%). Perioperative stroke did not occur in the asymptomatic group, but the risk was higher in those with prior stroke (19%) or with contralateral carotid occlusion (15%). The stroke risk for our patients with carotid disease having CABG without CEA is not known, but the literature reports rates as high as 14%. For our patients without known concomitant disease, the risk of permanent stroke was 1.0% (31/3012) for isolated CABG and 1.5% (7/482) for isolated CEA. The late results after CEA/CABG revealed a 5-year survival of 70% +/- 5%, which correlated with ejection fraction ( > or = 0.50, 81% +/- 5%; < 0.50, 45% +/- 11%; p < 0.003). Freedom from late permanent ipsilateral stroke was 97% +/- 2% at 8 years. Freedom from stroke at 5 years was lower among patients with a previous stroke (71% +/- 10%) compared with transiently symptomatic (90% +/- 4%) and asymptomatic (96% +/- 4%) patients (p < 0.03). Combined CEA/CABG is a useful option in this high-risk group of patients with extensive atherosclerosis; avoids a subsequent hospitalization, anesthetic, and delay period; and provides long-term protection from ipsilateral stroke.

Actuarial Analysis↗
PubMed1992

Optimal approach to the mitral valve: dissection of the interatrial groove.

Surgical exposure of the mitral valve has challenged surgeons for more than 30 years. Many ingenious, but often complex approaches have been devised during this time. Using the dissection of the interatrial groove to bring the left atrial incision more anterior and medial, we have achieved excellent exposure in more than 300 mitral valve procedures. This simple technique does not lengthen the procedure and is not associated with an increased risk of either early or late morbidity.

Boston↗
PubMed1992

Improved distribution of antegrade cardioplegic solution with simultaneous coronary sinus occlusion following acute coronary artery occlusion.

This study was designed to evaluate the distribution of cardioplegic solution infused antegradely with simultaneous coronary sinus occlusion. After 1 hr LAD occlusion, sheep were placed on cardiopulmonary bypass. Hearts were arrested with 300 ml of cold cardioplegia and replenished with two additional doses. In group I (n = 10), antegrade cardioplegia (ACP) was given alone; in group II (n = 9), ACP was given in combination with simultaneous coronary sinus occlusion. Microspheres were infused into the cardioplegic line to determine the antegrade distribution of the solution, while a different microsphere was injected into the anterior interventricular vein to detect the venous backflow of the solution. The data showed that myocardium distal to LAD occlusion in group II received more antegrade (0.17 +/- 0.02 versus 0.06 +/- 0.02 ml/g/min, P less than 0.01, in subendocardium; and 0.15 +/- 0.03 versus 0.09 +/- 0.02 ml/g/min, P = NS, in subepicardium) and retrograde (2181 +/- 455 versus 0 counts/g/min, P less than 0.01, in subendocardium; and 2,146 +/- 527 versus 0 counts/g/min, P less than 0.01, in subepicardium) distribution of cardioplegic solution in comparison to group I. We therefore conclude that simultaneous coronary sinus occlusion significantly improves the distribution of antegrade cardioplegic solution to the regionally occluded myocardium by increasing collateral flow as well as venous backflow.

Animals↗
PubMed1992

Improved surgical approach to left atrial appendage aneurysm.

Left atrial appendage aneurysm is a rare anomaly, which usually presents with arrhythmia or cerebral embolism. Diagnostic evaluation traditionally required cardiac catheterization, and surgical resection required cardiopulmonary bypass. Utilizing intraoperative transesophageal echocardiography and surgical stapling devices, we have streamlined our operative technique, allowing resection of a left atrial appendage aneurysm without cardiopulmonary bypass. This report of two cases treated over the past decade demonstrates the evolution of our surgical technique.

Adult↗
PubMed1992

Complete prevention of myocardial stunning, contracture, low-reflow, and edema after heart transplantation by blocking neutrophil adhesion molecules during reperfusion.

This study tested the hypothesis that preventing neutrophil adhesion during reperfusion, by blocking either the neutrophil membrane CD18 integrin complex or its endothelial and myocyte ligand, intercellular adhesion molecule-1 (ICAM-1), would reduce myocardial inflammation and edema and improve reflow and ventricular function after heart preservation and transplantation. After cardioplegia and insertion of a left ventricular balloon, rabbit hearts were heterotopically transplanted into recipient rabbits either immediately (immediate, n = 12) or after preservation in 4 degrees C saline (3 hours of ischemia, n = 33). Forty-five minutes before reperfusion, recipients of preserved hearts received intravenous infusions of either saline (vehicle, n = 13), anti-CD18 monoclonal antibody (Mab) R15.7 (2 mg/kg) (anti-CD18, n = 10), or anti-ICAM-1 Mab R1.1 (2 mg/kg) (anti-ICAM, n = 10). During 3 hours of reperfusion the slope of the peak-systolic pressure-volume relation and its volume-axis intercept, the exponential elastic coefficient of the end-diastolic pressure-volume relation, the unstressed ventricular volume, and the time constant of the exponential left ventricular pressure decay after dP/dtmin were serially measured. Myocardial blood flow was measured with microspheres from which coronary vascular resistance was calculated. After explanation, the degree of myocardial inflammation, estimated by tissue neutrophil sequestration (myeloperoxidase assay) and myocardial water content were determined. Within each group no significant differences in measurements made at 1, 2, and 3 hours of reperfusion were noted. Compared with the immediate transplantation group, the vehicle group demonstrated a significant increase in myeloperoxidase activity (3380 +/- 456 versus 1712 +/- 552 microU/gm, p < 0.05), coronary vascular resistance (115.5 +/- 13.4 versus 70.5 +/- 10.6 U/gm, p < 0.05), and myocardial water content (79.8% +/- 0.4% versus 75.6% +/- 1.3%, p < 0.05), a significant decrease in unstressed ventricular volume (a leftward shift in the end-diastolic pressure-volume relation) (-0.49 +/- 0.24 versus 0.28 +/- 0.21 ml, p < 0.05), and a marked prolongation in exponential left ventricular pressure delay after dP/dtmin (156.64 +/- 3.81 versus 37.25 +/- 3.34 msec, p < 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Abdomen↗
PubMed1992

Acute bacterial endocarditis. Optimizing surgical results.

BACKGROUND: Acute bacterial endocarditis continues to be a condition with high morbidity. Although the majority of patients are treated by high-dose antibiotics, a high-risk patient group requires surgical intervention, which is the subject of this article. METHODS AND RESULTS: From 1972 to 1991, 3,820 patients underwent heart valve replacement at the Brigham and Women's Hospital, Boston. Of this group, 158 patients underwent surgery for acute bacterial endocarditis: 109 had native valve endocarditis (NVE), and 49 had prosthetic valve endocarditis (PVE). There were 108 men and 50 women with a mean age of 49 years (range, 16-79 years); 64% were New York Heart Association functional class IV before surgery, and 12% of the group had a history of intravenous drug abuse. In both NVE and PVE groups, Streptococcus was the predominant infecting agent. Uncontrolled sepsis, progressive congestive failure, peripheral emboli, and echocardiographically demonstrated vegetations were the most common indications for surgery. Eighty-five percent of patients had a single-valve procedure, 15% had a multivalve procedure, and 34 patients had other associated major cardiac procedures. The operative mortality was 6% in NVE and 22% in PVE. Long-term survival at 10 years was 66% for NVE and 29% for PVE. Freedom from recurrent endocarditis at 10 years was 85% for NVE and 82% for PVE. The main factors associated with decreased survival overall were PVE and nonstreptococcal infection. CONCLUSIONS: The morbidity and mortality after surgical treatment of acute endocarditis depend on the site, the severity, and the subject infected. Early aggressive surgical intervention is indicated to optimize surgical results, especially in patients with nonstreptococcal infection or PVE.

Aortic Valve↗
PubMed1992

Improved recovery of heart transplants by combined use of oxygen-derived free radical scavengers and energy enhancement.

Oxygen free radical injury during reperfusion of ischemically stored heart transplants may further impair the ability of the transplanted heart to reuse substrate for recovery. We compared the effects of oxygen free radical scavengers, superoxide dismutase and catalase, either alone or combined with glucose-insulin-potassium, in an improved model of the heterotopically transplanted rat heart. Group 1 hearts (n = 8) received no preservation before transplantation and were transplanted immediately. Hearts in four other groups (n = 8 for each group) underwent cold storage (4 degrees to 6 degrees C) for 3 1/2 hours before transplantation. Five minutes before reperfusion of the transplanted hearts, recipient rats received one of the following intravenous treatments: saline (group 2), glucose-insulin-potassium (group 3), superoxide dismutase/catalase (group 4), and superoxide dismutase/catalase plus glucose-insulin-potassium (group 5). Left ventricular end-diastolic pressure, rate of rise of left ventricular pressure, myocardial blood flow, coronary resistance, and tissue adenosine triphosphate content of the heart transplants were assessed during or at the end of 2 hours of reperfusion. Hearts treated with superoxide dismutase/catalase alone showed improvement of end-diastolic pressure and myocardial blood flow. The use of glucose-insulin-potassium alone did not facilitate the recovery of transplanted hearts. In contrast, the combined use of superoxide dismutase/catalase plus glucose-insulin-potassium resulted in a superior recovery of all functional and hemodynamic parameters. These results indicate that free radical scavengers in the presence of glucose-insulin-potassium significantly improve functional recovery in the setting of heart transplantation.

Animals↗
PubMed1992

Controlled reperfusion of the regionally ischemic myocardium with leukocyte-depleted blood reduces stunning, the no-reflow phenomenon, and infarct size.

Open-chest sheep underwent 90 minutes' occlusion of the diagonal branch of the left anterior descending coronary artery, followed by vented cardiopulmonary bypass. After 30 minutes of cardioplegic arrest, simulating distal anastomoses, the occlusion on the coronary artery branch was released. Controlled reperfusion (40 to 50 mm Hg, 135 to 150 ml/min) for the first 20 minutes was delivered at the aortic root with either unmodified whole blood (control, n = 7) or blood passed through leukocyte filters (filters, n = 7). Serial measurements were made during 3 additional hours reperfusion off cardiopulmonary bypass. During ischemia, the major determinants of infarct size, which include area at risk, collateral myocardial blood flow, and rate-pressure product were not significantly different between groups. Overall, during reperfusion, mean left ventricular stroke work index in the filter group was greater than in the control group (28.7 +/- 5.8 versus 12.6 +/- 6.4 x 10(3) erg/gm, p less than 0.05), as was mean rate of rise of left ventricular pressure (1900 +/- 260 versus 1348 +/- 279 mm Hg/sec, p less than 0.05). Myocardial blood flow to the area at risk at 3 1/2 hours of reperfusion in the filter group was also significantly better than in the control group (0.57 +/- 0.15 versus 0.27 +/- 0.05 ml/min/gm, p less than 0.05), as was necrotic area as a percentage of area at risk (40% +/- 6% versus 70% +/- 5%, p less than 0.05). These results demonstrate amelioration of myocardial stunning and the no-reflow phenomenon, as well as decreased infarct size. We conclude that controlled reperfusion with leukocyte-depleted blood is superior to whole-blood reperfusion for the surgical treatment of acute regional ischemia.

Animals↗
PubMed1991

Mitral valve surgery: replacement vs reconstruction.

In comparative series, valve repair has been effective, with few of the problems--notably, thromboemboli--associated with replacement procedures. Although many patients are elderly and have coronary artery disease, reparative surgery not only is low-risk but also allows earlier intervention, before irreversible left ventricular damage occurs.

Echocardiography↗
PubMed1991

Doppler echocardiographic study of porcine bioprosthetic heart valves in the aortic valve position in patients without evidence of cardiac dysfunction.

To study the natural history of the hemodynamic performance of bioprosthetic heart valves, Doppler echocardiograms were recorded in a group of clinically stable patients at 2 and 5 years after replacement of native aortic valves with bioprosthetic valves. Eighteen patients completed a 2-year and 26 patients a 5-year follow-up examination. The effective orifice areas of identical models of bioprosthetic valves (Hancock II) were determined in vitro in a left-sided heart pulse duplicator system. In vivo Doppler-derived effective orifice areas were compared with the in vitro measurements for the same valve size. At both the 2- and 5-year follow-up examinations, the Doppler-derived effective orifice area was significantly less than the in vitro area (p less than 0.0001 at each interval). Ten of 16 valves evaluated serially decreased greater than 0.20 cm2 in the Doppler-derived effective orifice area between studies. The mean decrease in effective orifice area in valves evaluated serially was 0.25 +/- 0.29 cm2 (p less than 0.005). The peak transaortic gradient increased from 21 +/- 6 to 27 +/- 8 mm Hg (p less than 0.01). The mean transaortic gradient increased from 12 +/- 4 to 15 +/- 7 mm Hg (p less than 0.05). It is concluded that serial Doppler echocardiographic studies demonstrate a deterioration in the hemodynamic performance of bioprosthetic valves over time in patients with no symptoms or signs of valvular dysfunction and that Doppler echocardiography may be useful for identifying subclinical bioprosthetic valvular dysfunction.

Adult↗
PubMed1991

Doppler echocardiographic comparison of the Carpentier and Duran anuloplasty rings versus no ring after mitral valve repair for mitral regurgitation.

To compare the hemodynamic results of different anuloplasty techniques of primary valve repair for mitral regurgitation, 122 patients were prospectively studied with Doppler echocardiograms 5 to 10 days after operation. Seventy-seven patients had mitral valve prolapse, 27 had coronary artery disease, 13 patients had rheumatic mitral valve lesions and 5 patients had infective endocarditis. Forty-eight patients received the flexible Duran ring, 46 received the more rigid Carpentier ring and 28 patients received no ring. Doppler echocardiography demonstrated a significant decrease in mitral valve area estimated by the pressure half-time method in patients who received either a Carpentier (2.6 +/- 0.8 cm2) or Duran ring (2.8 +/- 0.8 cm2) when compared with patients who received no ring (3.2 +/- 0.7 cm2) (p = 0.01). No significant differences were observed for peak transmitral diastolic velocity, peak transmitral diastolic gradient, or the grade of mitral regurgitation by color flow Doppler mapping between patients with and without rings. The etiology of mitral disease and concomitant surgical procedures accompanying mitral valve repair did not significantly influence mitral valve area, peak velocity or peak gradient. These data suggest that Carpentier and Duran rings decrease the hemodynamic mitral valve area; however, the decrease in valve area is small and not associated with a clinically important increase in transvalvular gradient.

Echocardiography, Doppler↗
PubMed1991

Frequency of deep venous thrombosis in asymptomatic patients with coronary artery bypass grafts.

The frequency of deep vein thrombosis (DVT) in patients undergoing coronary artery bypass graft (CABG) surgery has not been established. Therefore to estimate the frequency of clinically silent DVT, we performed ultrasound examinations of the leg veins in 29 asymptomatic CABG patients before hospital discharge. We used high-resolution B-mode ultrasonography with color Doppler imaging. Fourteen (48.3%, 95% confidence interval 30.1 to 66.4%) had 20 documented leg vein thromboses, and all but one patient had DVT limited to the calf veins. Of the 20 thrombi 10 (50.0%) were present in the leg ipsilateral and 10 (50.0%) in the leg contralateral to the saphenous vein harvest site. None of the DVTs were suspected clinically. DVT was not associated with any local sign attributed to saphenous vein harvest such as pitting edema, incisional drainage, or local tenderness or with any putative risk factor for DVT such as cigarette use, distant history of malignancy, or varicose veins. Follow-up of these patients 5 to 11 months after CABG surgery showed no clinical evidence of DVT or pulmonary embolism. Our findings indicate that asymptomatic DVT of the calf occurs with surprisingly high frequency, 44.8% after CABG surgery. Future studies in patients undergoing CABG surgery should address the natural history of asymptomatic DVT, determine its clinical importance, and develop optimal strategies for prophylaxis and treatment.

Aged↗
PubMed1991

Pulmonary artery balloon counterpulsation for intraoperative right ventricular failure.

Two cases of severe low cardiac output and right ventricular failure after coronary artery bypass grafting necessitated pulmonary artery balloon counterpulsation after intraaortic balloon pumping and maximal inotropic/pressor support were unsuccessful in maintaining a satisfactory cardiac output. Hemodynamic improvement was sufficient to allow removal of the device 2 and 3 days postoperatively, with survival in 1 patient. Pulmonary artery counterpulsation is less morbid in comparison with other mechanical methods of right ventricular support and is applicable in right ventricular failure of intermediate severity.

Aged↗