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Biomedical subjects

L H Cohn

Publications and source records attributed to L H Cohn.

At least 163 records · Page 9Linked to original sources
PubMed1989

Automated control of postoperative hypertension: a prospective, randomized multicenter study.

Hypertension after a cardiac operation is a frequent phenomenon. Complications resulting from this include bleeding, disruption of vascular suture lines, subendocardial ischemia, and possible cerebrovascular accidents. Treatment with sodium nitroprusside has become accepted practice to prevent these complications. To improve control of arterial blood pressure, a closed-loop system for sodium nitroprusside administration was developed. A prospective, randomized multicenter study was carried out postoperatively in 180 cardiac surgical patients to evaluate the performance of this system compared with manual control of infusion. Adherence of mean arterial blood pressure to +/- 10% of the target blood pressure occurred 85% of the time with the automatic system and 61% of the time with manual regulation (p less than 0.0001). With the automatic system, there was less hypertension (9% versus 22%; p less than 0.0001) and hypotension (6% versus 22%; p less than 0.0001). The superior control of hypertension was achieved more rapidly with less requirement for nurse regulation of infusion rate. The superior control of blood pressure resulted in less chest tube drainage in the automatic mode (720 mL versus 840 mL; p less than 0.05).

Aged↗
PubMed1989

Right thoracotomy, femorofemoral bypass, and deep hypothermia for re-replacement of the mitral valve.

Ten patients underwent mitral valve re-replacement for the third to sixth time through a right thoracotomy using one-lung anesthesia, femorofemoral bypass, profound systemic hypothermia, and low-flow perfusion without aortic cross-clamping or cardioplegia. The indications for this approach were previous mediastinitis, severe right ventricular hypertension with multiple previous sternotomies, intact coronary artery bypass graft, or previous aortic valve replacement. There was 1 operative death, which was due to end-stage pulmonary hypertension and intractable right heart failure. Blood loss was minimal, and there was no major postoperative morbidity in the 9 surviving patients except for supraventricular arrhythmias.

Adult↗
PubMed1989

The Hancock modified-orifice porcine bioprosthetic valve: 1976-1988.

The Hancock modified-orifice porcine valve was fabricated as a result of documented obstruction of the Hancock standard porcine valve in small sizes related to the retained muscle bar of the right coronary cusp. We implanted the first clinical Hancock modified-orifice valve in 1976, and have used this valve for aortic valve replacement to the present time. This analysis compares and contrasts the clinical performance of 401 Hancock standard and 385 Hancock modified-orifice valves over a period of 10 years. Statistical significance in actuarial curves at 120 months was noted in long-term survival and thromboemboli. There was a slightly smaller amount of structural valve degeneration and incidence of reoperation with the modified-orifice valve compared with the standard valve. The Hancock modified-orifice valve has proven to be a satisfactory aortic valve replacement device, and its complex fabrication has withstood the test of time.

Aged↗
PubMed1989

Fifteen-year experience with 1678 Hancock porcine bioprosthetic heart valve replacements.

The Hancock porcine valve was the first commercially available biologic heart valve and has been in continuous use at the Brigham and Women's Hospital since January 1972. Through December 1987 we implanted 1678 valves in 1533 patients (885 male; 648 female; 17 to 95 years of age, with a mean of 60 years). There were 825 aortic valve replacements (AVR), 562 isolated mitral valve replacements (MVR), and 146 aortic mitral replacements (DVR). Ninety-four per cent of the patients were functional class III or IV. Associated coronary bypass was done in 25% of patients. Four per cent of patients were lost to follow up during a 1- to 16-year period with a mean of 6 years. Morbidity and mortality rates on a actuarial basis were calculated 10 and 15 years after operation for AVR, MVR, and DVR. The data indicates that the probability of reoperation for structural valve failure is quite reasonable as of 10 years, but from 10 to 15 years the numbers sharply fall off so that the probable effective life of the valve is 10 years. However in the elderly age group (equal to or greater than 70 years of age) the incidence of structural valve degeneration is markedly diminished, making this an ideal valve substitute for the elderly. It is also an ideal valve substitute in any patient who has a contraindication to long-term anticoagulation because of current medical or surgical problems.

Adolescent↗
PubMed1989

Valve replacement for infective endocarditis: an overview.

Infective endocarditis, both in the native and prosthetic valve, presents a tremendous challenge to the cardiologist and cardiovascular surgeon, as well as the infection specialist. The timing of surgery is critical but it would appear that aggressive surgical intervention is indicated when there is persistent sepsis, continuing congestive heart failure, signs of nonfatal emboli, or in association with certain organisms such as staphylococcus, pseudomonas, or fungal organisms. Cardiac catheterization would not appear to add greatly to the diagnosis except to document the presence of coronary artery disease. The risk of surgery in patients with no annular abscess is low but the recurrence rate tends to be highly dependent on the organism. Similarly, patients who have annular abscesses tend to provide the greatest challenge for the surgeon and despite the use of newer prosthetic and biological prostheses and an overall more aggressive approach, this pathological entity, particularly in conjunction with prosthetic valve endocarditis, has a high mortality and a high recurrence rate.

Bioprosthesis↗
PubMed1989

Surgical treatment of acute myocardial infarction.

In 1989 the following indications for surgical treatment of acute myocardial infarction are: (1) acute evolving myocardial infarction less than 6 h from onset, in patients in whom percutaneous transluminal coronary angioplasty (PTCA) or streptokinase (SK), depending on the coronary anatomy, has been unsuccessful; if single vessel disease, coronary artery bypass grafting (CABG) is unlikely; if multiple vessel disease, CABG is preferable to SK/PTCA unless a very major 'culprit' lesion can be identified with certainty; (2) postinfarction angina hours to days after a transmural myocardial infarction unyielding to maximal medical therapy and in patients with a coronary artery obstruction not amenable to PTCA; (3) occlusion of a coronary artery during cardiac catheterization that cannot be fixed by PTCA and/or SK; (4) occlusion of a coronary artery during PTCA causing hemodynamic obstruction and a threatened myocardium subtended by the obstructed coronary artery; (5) balloon-dependent patients in cardiogenic shock without mechanical defects who have adequate residual left ventricular function as determined by regional wall motion studies; (6) ventricular septal defect secondary to myocardial infarction unless there is terminal organ damage; (7) mitral valve replacement with coronary bypass for acute papillary muscle rupture; (8) semi-emergency cardiac transplantation, either with or without a mechanical bridge to transplant in young individuals (less than 50 years) who have suffered massive destruction of left ventricular myocardium by an acute coronary occlusion with or without recurring ventricular tachyarrhythmias. Ejection fraction in this clinical category is always under 0.20 and usually under 0.15.

Angina Pectoris↗
PubMed1989

Sequentially paced heterotopic heart transplant in the left chest provides improved circulatory support for the failed left ventricle. A potential biologic bridge to orthotopic transplantation.

Acute experimental transplantation of an allograft heart in a heterotopic position was performed in 14 sheep. The donor heart was implanted in the left side of the chest with left atrial, aortic, and pulmonary artery anastomoses. Hemodynamic studies were performed to evaluate the physiologic effects of the procedure, particularly when recipient left ventricular failure was produced by inflow and outflow obstruction. Pacing techniques were developed and tested to coordinate the rhythm of the two hearts either synchronously or sequentially with variable intervals between depolarization of the two hearts. Hemodynamic studies were performed to evaluate the rhythm that would most optimize the physiology. The cardiac index remained essentially unchanged when the dominant circulatory support was shifted from recipient left ventricle to donor left ventricle by producing recipient left ventricular failure (3.79 +/- 0.6 to 3.30 +/- 0.8, p = no significant difference). Consistent and reliable paced rhythms were achieved in each case. The cardiac index was significantly higher when the hearts were paced sequentially rather than synchronously (3.76 +/- 0.5 versus 3.29 +/- 0.5, p less than 0.04). Allograft donor hearts small in size or slightly inadequate otherwise, which may be unsuitable for orthotopic heart transplantation, may still be used heterotopically for short-term support. Their use would maximize the use of all donor organs and the survival of patients awaiting a suitable organ. Further, it may also be possible to use sequentially paced xenografts heterotopically for short-term left ventricular assistance as a bridge to orthotopic heart transplantation.

Animals↗
PubMed1989

Mitral valve repair for myxomatous degeneration and prolapse of the mitral valve.

From 1984 to 1988, 129 mitral valve reconstructions were done for primary pure mitral regurgitation. Sixty-two (48%) were done for myxomatous degeneration and prolapse of the mitral valve. Anterior leaflet resection was performed in seven patients, posterior leaflet resection in 46, anteroposterior resection in four; five patients received only a ring annuloplasty. Eight patients had coronary bypass grafts. Twenty-four patients received a Carpentier-Edwards annuloplasty ring, 24 a Duran ring, and 14 patients had no ring. Follow-up was 1 to 50 months (mean, 13 months). No patient was lost to follow-up. There was one operative death from gastrointestinal bleeding and two late deaths (one from suicide and one from a myocardial infarction), and the probability of survival at 48 months was 84% +/- 15%. There were no thromboembolic episodes or episodes of endocarditis. However, there were five reoperations (9%) with freedom from reoperation at 48 months of 85% +/- 5%. There was one major anticoagulant hemorrhage. Freedom from all morbidity at 48 months was 81% +/- 8%. Postoperative echocardiographic data in the three different groups of patients undergoing repair on the basis of annuloplasty treatment showed that the peak gradient was less and the valve area was slightly greater with no annuloplasty ring.

Adult↗
PubMed1988

Surgery for mitral regurgitation.

Mitral regurgitation is a valvular heart lesion that is difficult to diagnose accurately; thus, it is difficult to determine the appropriate timing for surgical correction. With increasing use of reparative techniques, including local resection of valve pathology and placement of an annuloplasty ring, and the realization that chronic atrial fibrillation leads to decreased long-term survival, the timing of surgery has changed. In addition, serial noninvasive studies have indicated that despite the absence of symptoms, patients may progress to a myopathic condition if the regurgitation progresses over a long period and surgery is not performed when signs of left ventricular dysfunction are evident. Preservation of the papillary muscle is also extremely important for late postoperative function in patients with mitral regurgitation, and reparative surgery that preserves both anterior and posterior papillary muscle complexes and continuity with the anulus appears to satisfy this assumption. Worldwide experience is reviewed and I present conclusions related to the appropriate indications for mitral valve repair or replacement in patients with mitral regurgitation.

Atrial Fibrillation↗
PubMed1988

Thromboxane synthetase inhibition reduces ventricular irritability after coronary occlusion and reperfusion.

Reperfusion of ischemic tissue is responsible for production of metabolites with deleterious local vascular effects. Thromboxane A2, a potent vasoconstrictor and platelet aggregator, has been implicated as a mediator of the "reperfusion injury." We studied the effect of an experimental thromboxane synthetase inhibitor, OKY-046, on coronary sinus thromboxane levels, ventricular irritability, myocardial contractility, infarct salvage, and histologic features of reperfusion. Sixteen sheep were randomized to OKY-046, 3 mg/kg, or saline vehicle before 3-hour occlusion and subsequent reperfusion of the left anterior descending artery. The OKY group demonstrated less ventricular irritability as measured by incidence of ventricular fibrillation and necessity for countershock to reverse tachyarrhythmias. Coronary sinus thromboxane levels were significantly lower in the OKY group compared with the control group. There is additional evidence to suggest that OKY increases infarct salvage and attenuates histologic features of microcirculatory damage.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Comparative morbidity of mitral valve repair versus replacement for mitral regurgitation with and without coronary artery disease.

Mitral valve repair has been increasingly used at our hospital for mitral regurgitation with and without coronary disease. From January, 1984, to June, 1987, of 338 patients undergoing all forms of mitral valve surgery, 140 had first-time surgery for pure mitral regurgitation: 75 had valve repair, and 65 had valve replacement. Thirty-three of 75 (44%) had concomitant coronary bypass in the repair group, while 21 of 65 (32%) had coronary bypass in the replacement group. The mean functional class (3.4 versus 3.5), age (60 versus 61 years), and preoperative hemodynamics were similar in both groups. The cause of mitral regurgitation in the repair group was myxomatous change in 32 patients, ischemia in 27, rheumatic valve disease in 12, and endocarditis in 4. A Carpentier ring was used in 46, a Duran ring was used in 11, and none was used in 18. The operative mortality was 3 of 75 patients (4%) in the repair group, all with coronary artery bypass grafting, versus 2 of 65 patients (3%) in the replacement group, 1 of whom had undergone coronary artery bypass grafting. The mean postoperative functional class 15 months postoperatively was 1.12 in the repair group versus 1.15 in the replacement group. There were 7 late deaths in the replacement group and only 3 late deaths in the repair group. Actuarial survival at 30 months was 85 +/- 6% for the replacement group and 94 +/- 4% for the repair group. There were 5 late emboli (1 fatal, 4 nonfatal) after valve replacement and none after valve repair (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Ligation of the left atrial appendage using an automatic surgical stapler.

We investigated the use of an automatic surgical stapler for ligation of the atrial appendage in sheep, and then applied this technique in patients. Fourteen adult sheep underwent ligation of the left atrial appendage using a surgical stapler with a rotating head and either absorbable or stainless steel staples. In 4 sheep, killed after two hours, no hemorrhage or intraatrial thrombus was observed acutely. Ten sheep were allowed to recover for 90 to 100 days, twice the expected absorption time of absorbable staples. There was complete obliteration of the left atrial appendage without evidence of intraatrial thrombus or staple migration. The absorbable staples were completely reabsorbed. We subsequently used this technique in 5 patients undergoing mitral valve procedures. There were no complications, and adequate obliteration of the atrial appendage was achieved.

Animals↗
PubMed1988

Considerations in the surgical management of left atrial myxoma.

Myxomas are the most common tumors of the heart. They are frequently located in the left atrium and produce symptoms when they fragment and cause systemic emboli or when they interfere with cardiac valvular function and cause pulmonary congestion. Careful surgical management of these lesions should be curative with minimum early and late morbidity and mortality. Optimal operative technique emphasizes minimal manipulation of the heart before institution of cardiopulmonary bypass and aortic cross-clamping and careful examination of intracardiac chambers with meticulous removal of myxomatous debris. Using these techniques, 17 patients have been treated successfully at the Brigham and Women's Hospital. There were no operative deaths and no significant perioperative morbidity. Fifteen patients are asymptomatic, and one patient has minimal shortness of breath an average of 57 months after surgery. One patient died of leukemia 15 months postoperatively. No recurrent myxomas have been identified, and no patients have symptoms of other cardiac disease.

Adult↗