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Biomedical subjects

L H Cohn

Publications and source records attributed to L H Cohn.

At least 199 records · Page 11Linked to original sources
PubMed1986

Long-term survival of more than 2,000 patients after coronary artery bypass grafting.

Among 2,004 patients who underwent their first coronary artery bypass graft operation between January 1970 and December 1980 without concomitant valve replacement or aneurysmectomy, life-table survival was 89% at 5 years and 80% at 8 years after surgery. In a multivariate Cox model analysis, the independent correlates of long-term survival were emergent operation with cardiogenic shock (multivariate mortality rate ratio [RR] = 14.0), use of a postoperative intraaortic balloon pump (RR = 3.9), ejection fraction less than 50% (RR = 2.4), preoperative history of congestive heart failure (RR = 2.2), cardiopulmonary bypass time (RR = 1.4 for each 30-minute increment), uncorrected mitral regurgitation (RR = 1.5 for each increment of angiographic gradation), left main coronary artery narrowing (RR = 1.7) and diabetes (RR = 1.6). After controlling for these factors, age, sex and the percentage of narrowings that were bypassed were not independent correlates of long-term survival.

Adult↗
PubMed1986

Comparison of dopamine and dobutamine in patients requiring postoperative circulatory support.

We compared dopamine and dobutamine following cardiac surgery in a sequential cross-over study of 9 patients who required inotropic support after volume replenishment. Seven patients had mitral valve replacement, 2 with simultaneous coronary revascularization (CABG), and 1 each with simultaneous tricuspid annuloplasty and aortic valve replacement; 1 had isolated CABG and 1 had repair of a postinfarction ventricular septal defect. Heart rate, right and left atrial pressures, pulmonary and mean arterial pressure, systemic and pulmonary vascular resistance, and cardiac index were measured and calculated. Inotropic support with dopamine or dobutamine was begun for treatment of low cardiac index within 12 hours postoperatively. Measurements were made after 20 minutes on either agent at 5-10 micrograms/kg per min when cardiac output and general clinical state were stable. Each patient was then switched to the other agent at approximately the same dose rate, titrating the dosage to the same cardiac output, and repeat measurements were made at 20 minutes when again stable. Similar dosages of dopamine (6.2 +/- 1.7 micrograms/kg/min) and dobutamine (6.7 +/- 2.5 micrograms/kg/min) produced equivalent heart rate (103 +/- 19 vs. 102 +/- 13 beats/min, p = NS), cardiac index (2.8 +/- 1.1 vs. 2.9 +/- 1.2 l/min/m2, p = NS), and pulmonary arterial pressure and vascular resistance. Mean systemic arterial pressure was significantly lower with dobutamine (59 +/- 5 vs. 67 +/- 7 mmHg, p less than 0.05) as were mean left (14 +/- 5 vs. 18 +/- 6 mmHg, p less than 0.0001) and right (9 +/- 2 vs. 11 +/- 2 mmHg, p less than 0.05) arterial pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Hemodynamic, metabolic, and morphological effects of cardiopulmonary bypass with a fluorocarbon priming solution.

Systemic perfusion, myocardial contractility, and morphological changes during and after cardiopulmonary bypass (CPB) were investigated in 22 greyhounds; Fluosol-DA 20% (FDA) and normal saline (NaCl) were compared as priming solutions for hypothermic (25 degrees C) CPB. Hemodynamic and oxygenation indices were similar in all groups. Animals with fluorocarbon primes had higher serum lactate concentrations (mean +/- standard error of the mean [SEM]) during CPB (NaCl 1.64 +/- 0.2, FDA 2.39 +/- 0.3, p less than 0.01), representing an increase over the control of 12% and 319% in the NaCl and FDA groups, respectively. After CPB, serum lactate concentration remained elevated in the FDA group, but it returned to the level of the control in the NaCl group (NaCl 1.49 +/- 0.5, FDA 2.29 +/- 1.1, p less than 0.01); increases over the control level were 7% and 302% in the NaCl and FDA groups, respectively. Myocardial contractility after CPB, expressed as dP/dt[40], was similar in the two experimental groups. Three weeks after CPB, a histological examination by light microscopy of multiple organs obtained from a separate group of 12 animals treated similarly was performed, demonstrating no significant morphological differences between animals primed with fluorocarbon or with saline. The results suggest that FDA is a satisfactory priming agent for hypothermic CPB. It adequately preserves myocardial function and causes no adverse morphological changes, but a persistent, as yet unexplained, elevation in serum lactate concentration occurs.

Acid-Base Equilibrium↗
PubMed1986

Operative management of the calcified patent ductus arteriosus.

A technique in which the calcified adult patent ductus arteriosus can be safely divided using a left-sided thoracotomy approach without the need for transient aortic cross-clamping or cardiopulmonary bypass is described. Concentric, nested vascular clamps are placed on the noncalcified pulmonary artery side of the ductus, so that dissection and clamping of the heavily calcified ductus-aortic junction are unnecessary. The pulmonary artery rim surrounding the insertion of the ductus can be divided between the two clamps and oversewn.

Adult↗
PubMed1986

Inotropic response of the salvaged myocardium after acute coronary occlusion.

We determined the response of the reperfused myocardium to inotropic stimulation with dobutamine hydrochloride. The middle part of the left anterior descending coronary artery (LAD) was occluded in 15 greyhounds for 3 hours. Group 1 (N = 8) was reperfused for 3 hours in the beating, working heart. Group 2 (N = 7) was put on cardiopulmonary bypass (CPB) for 1 hour, received 500 ml of potassium cardioplegia in the aortic root and in the area of ischemia through an internal mammary-LAD graft, and the LAD was reperfused off CPB for 3 hours. After 3 hours of reperfusion, dobutamine was given at 10 micrograms/kg/min for 20 minutes. Regional myocardial function was determined with subendocardial ultrasonic crystals in the area of ischemia and in the base of the heart; segmental contractility was determined from the ratio of peak left ventricular pressure to end-systolic segment length; and global contractility was determined by the slope of the ventricular pressure wave at a developed pressure of 40 mm Hg. Measurements were made prior to LAD occlusion (control), at the end of 3 hours of reperfusion (6 hours from the beginning of occlusion), and after 20 minutes of dobutamine infusion. Dobutamine infusion improved segmental function in all animals compared with 3 hours of reperfusion. The study shows that the reperfused myocardium responds favorably to inotropic stimulation after 3 hours of occlusion and 3 hours of reperfusion, and that the contractile response both to reperfusion and to inotropic stimulation is greatly affected by the method of reperfusion.

Animals↗
PubMed1986

Clinical response to coronary artery reoperations.

Repeat coronary artery bypass operations were performed on 112 patients at a university hospital between 1971 and 1981. When compared with patients who did poorly after a first operation but did not have repeat surgery, patients undergoing repeat surgery tended to be younger, to have a higher smoking rate and to have fewer prior myocardial infarctions, fewer diseased vessels and fewer lesions in distal vessels. At least 1 graft was occluded in 83% of patients undergoing reoperation, and a mean of 1.7 grafts were placed at reoperation. The operative mortality rate was 4%, with a follow-up mortality rate of 6% at a mean of 3.8 years. After reoperation, patients initially showed improvement to a mean specific activity scale class of 1.6, compared with 2.4 before the first operation and 2.7 before the second operation. The principal correlate of a better long-term symptomatic response compared with that in the period before the first operation was a lower serum cholesterol level, whereas the principal correlate of a better symptomatic response compared with that in the period just before the reoperation was the left ventricular ejection fraction. As recurrent symptoms after a first coronary artery operation become more prevalent, consideration of the selection factors and prognostic correlates of reoperation will become increasingly important.

Coronary Angiography↗
PubMed1986

Augmentation of venous return by adrenergic agonists during spinal anesthesia.

To test the effectiveness of adrenergic agonists in correcting the vascular sequelae of spinal anesthesia, we used venous reservoir volume (RV) and mean arterial pressure (MAP) as indices of the changes in venous capacitance and arterial resistance produced by adrenergic agonists in dogs anesthetized with pentobarbital and undergoing cardiopulmonary bypass (CPB). A CPB-based technique was chosen both to prevent drug and reflex effects on the heart from influencing the results and to provide a convenient means by which to monitor venous capacitance. Total spinal anesthesia significantly decreased both RV and MAP relative to steady-state CPB values. Return of these hemodynamic alterations to baseline was attempted using pure alpha- and beta-adrenergic agonists, and a mixed adrenergic agonist (phenylephrine, isoproterenol, and ephedrine, respectively). Isoproterenol increased RV, but further decreased MAP. Phenylephrine increased MAP but not RV. Ephedrine increased both MAP and RV. We conclude that a mixed adrenergic agonist such as ephedrine more ideally corrects the noncardiac circulatory sequelae of spinal anesthesia than does either a pure alpha- or beta-adrenergic agonist.

Adrenergic alpha-Agonists↗
PubMed1986

Femorofemoral bypass to relieve acute leg ischemia during intra-aortic balloon pump cardiac support.

This study reports our experience with 10 patients who underwent the emergent construction of a femorofemoral bypass graft to salvage an acutely ischemic lower extremity following the insertion of a transfemoral intra-aortic balloon pump catheter. All patients had excellent resolution of the ischemia and salvage of the extremity. Half of the procedures were done at the bedside with the remainder performed in the operating room. No long-term infections or ischemic sequelae resulted from the procedures in the nine patients available for long-term follow-up. The use of femorofemoral bypass grafting is, therefore, recommended in patients with severe ipsilateral limb ischemia who are dependent on an intra-aortic balloon pump to prevent extremity tissue loss as well as the systemic metabolic manifestations of ongoing tissue ischemia and necrosis. Patient selection, technical considerations, and postoperative management are discussed.

Adult↗
PubMed1985

Quantitative anatomic analysis of "stent creep" of explanted Hancock standard porcine bioprostheses used for cardiac valve replacement.

The degree of progressive inward deflection of the stent posts ("stent creep") during function of Hancock standard orifice porcine aortic valve bioprostheses is unknown. The present investigation determines, using a quantitative geometric analysis of clinically removed bioprostheses, the contribution of stent creep to progressive reduction in the outflow orifice area of these valves. Fifty-four Hancock standard orifice porcine aortic valve bioprostheses obtained at reoperation or at autopsy of 50 patients were studied; 47 of these were removed more than 21 months postoperatively. The projected geometric outflow orifice area of each prosthesis was planimetrically measured. To compare prostheses through the entire range of available sizes, this measured area was divided by that of an unimplanted valve of the same size to calculate a ratio designated the "normalized outflow area ratio" (NOAR). Thus, by definition, for all unimplanted standards, NOAR was 1.00. In 7 prostheses in place for less than 1 month, the NOAR was 1.00 +/- 0.03 (mean +/- standard deviation). In 47 prostheses removed 21 to 126 months postoperative, the NOAR was 0.91 +/- 0.08. The relation between NOAR and duration of function determined by linear regression was NOAR = 0.955 - 4.560 X 10(-4) X Duration (in months). The minimum NOAR found was 0.74; the NOAR was less than 0.80 in 4 prostheses (8% of long-term valves). Thus, stent creep is usually not prominent after long-term function of Hancock standard orifice procine bioprostheses and suggests that clinically important progressive reduction of the geometric outflow orifice is infrequent.

Adult↗
PubMed1985

Long-term results of open mitral valve reconstruction for mitral stenosis.

Open mitral reconstruction for rheumatic mitral stenosis (MS) was performed in 120 patients, 101 women and 19 men, aged 22 to 75 years (mean 49). Nine patients were functional class II, 106 class III, 5 class IV; 13 only underwent noninvasive studies, including echocardiography, before surgery, while 107 had preoperative cardiac catheterization studies. The latter showed a mean valve area of 1.09 cm2 and a pulmonary artery wedge to left ventricular mean diastolic gradient of 14 mm Hg. Cardiopulmonary bypass was used in all patients for open reconstruction under direct vision. Superior commissurotomy was done in 115 patients, inferior in 114, papillary muscles were incised and chordae lengthened in 39 and calcium was excised from valve leaflets in 23. Suture or ring anuloplasty was not required in any patient. The series was begun January 1972 and terminated in January 1984. Personal follow up was conducted in July 1984. There were no operative deaths in the 120 patients. There were 5 late deaths, all from noncardiac causes. The mean follow-up time was 53 months. The actuarial probability of survival at 10 years was 95 +/- 2%. Thromboemboli occurred in 9 patients; the probability of freedom from thromboemboli at 10 years was 91 +/- 3% and the linearized rate was 1.8%/patient-year of follow-up. Reoperation was required in 9 patients, an absolute incidence of 7.5% and an annual incidence of 1.7%/patient year. At 10 years the probability of freedom from reoperation was 84 +/- 5%.

Actuarial Analysis↗
PubMed1985

Aggressive surgical management of post-infarction angina: results of myocardial revascularization early after transmural infarction.

In our Division of Cardiothoracic Surgery between 1970 and 1982, 110 patients (88 males and 22 females) had coronary artery bypass grafts (CABG) performed for unstable angina pectoris after acute transmural myocardial infarction. Fifty-one patients (mean age 59 years) had CABG within 2 weeks of myocardial infarction (Group 1); and 59 patients (mean age 56 years) (p = NS) within 6 weeks of myocardial infarction (Group 2). The incidence of preoperative arrhythmias, left ventricular ejection fraction, end-diastolic pressure, and the number of vessels diseased were similar in Groups 1 and 2. The incidence of cardiogenic shock was higher in Group 1 (16/51, 31% vs 2/59, 3% [p < 0.001]). This was also the case with the use of the intraaortic balloon (32/51, 63% vs 12/59, 20% [p < 0.001]), and the need for emergency operation (29/51, 57% vs 4/59, 7% [p < 0.001]). The mean number of grafts was 2.8 in Group 1 and 3.0 in Group 2 (p = NS). Operative mortality was 20% (10/51) in Group 1 and 7% (4/59) in Group 2 (p < 0.01). Excluding patients in cardiogenic shock, operative mortality was 0% (0/35) in Group 1 and 5% (3/57) in Group 2 (p = NS). Incidences of late death, recurrent angina, and permanent disability were similar during mean follow-up times of 3.2 years in Group 1 and 4.1 years in Group 2. Actuarial probability of survival was 96% at 1 year and 83% at 5 years. Myocardial revascularization early after transmural myocardial infarction has a low risk, especially in the absence of cardiogenic shock. These results justify an aggressive approach to unstable angina, including patients within 2 weeks of transmural infarction.

Journal Article↗
PubMed1985

Early and late risk of mitral valve replacement. A 12 year concomitant comparison of the porcine bioprosthetic and prosthetic disc mitral valves.

A consecutive series of 706 mitral valve replacements was performed from January, 1972, to January, 1984. The follow-up ranged from 6 to 150 months with a mean of 50 and a median of 43 months. Seven percent (50) of the patient were lost to follow-up. There were 243 men and 463 women, whose ages ranged from 17 to 86 years (mean 58). A porcine bioprosthetic valve was implanted in 528 patients (514 Hancock and 14 Carpentier-Edwards valves) and a prosthetic disc valve in 178 patients (102 standard disc Björk-Shiley, 34 Beall, and 42 Harken disc valves). Seven patients were in Functional Class II, 325 in Class III, and 374 in Class IV. A concomitant operative procedure was performed in 253 of the 706 patients (36%). Mitral regurgitation was the primary hemodynamic lesion in 363 and mitral stenosis in 343. Operative mortality figures were as follows: 77 of 706 (11%) for the overall group, 34 of 453 (7.5%) for isolated mitral valve replacement, 30 of 169 (17.5%, p = 0.001) for mitral replacement plus coronary bypass, 49 of 528 (9%) for the bioprosthetic valve group, and 28 of 178 (16%) for the prosthetic disc valve group (p = 0.01). After the operation, 262 patients were in Functional Class I, 99 in Class II, and 18 in Class III. The long-term survival rate was significantly lower in patients who had an associated procedure (45% +/- 6%), who had mitral regurgitation rather than mitral stenosis (53% +/- 5% versus 67% +/- 4%) (p = 0.002), who were in Functional Class IV rather than Classes I to III (51% +/- 4% versus 70% +/- 4%) (p = 0.001), and who received a prosthetic disc valve rather than a bioprosthesis (40% +/- 6% versus 67% +/- 4%) (p = 0.001). Thromboembolic rates were significantly higher with prosthetic valves than with bioprosthetic valves (4.6% +/- 0.22% versus 2.4% +/- 0.5% per patient-year of follow-up), and the incidence of anticoagulant-related hemorrhage was significantly higher in the prosthetic valve group (1.65% versus 0.43% per patient-year). Primary valve dysfunction was significantly more common in the bioprostheses (1.23% versus 0.40% per patient-year).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1985

Mitral valve surgery: reconstruction versus replacement.

The debate between reconstructive versus replacement operations for the diseased mitral valve has taken on new importance as the late results for survival, thromboembolic phenomena and incidence of reoperation from a variety of prosthetic and bioprosthetic cardiac valves have now become available. Three series of patients at the Brigham and Women's Hospital from 1972-84, representing 120 patients undergoing open mitral valve reconstruction for mitral stenosis, 348 patients undergoing mitral valve replacement for mitral stenosis, and 363 patients undergoing mitral valve replacement for mitral valve regurgitation are presented. The operative mortality in the reconstruction group was 0, there were 5 late deaths, all non-cardiac, 9 patients had a thromboembolism (1.8%/pt year), and 9 patients required reoperation (1.7%/pt year). For those who had mitral valve replacement for mitral stenosis the operative mortality was 10%, 6% for isolated replacement, 20% if this included a coronary artery bypass. At 9 years the long-term survival was 68 +/- 4%, freedom from thromboembolism 80 +/- 4%, and freedom from valve dysfunction 87 +/- 4%. In the replacement group for mitral regurgitation operative mortality was 11%, 20% with coronary artery bypass. Operative survival was 53 +/- 5% at 9 years, freedom from thromboembolism was 87 +/- 3%, and freedom from valve dysfunction was 91 +/- 4%.

Adult↗