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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
PubMed1998

Aortic valve operations under deep hypothermic circulatory arrest for the porcelain aorta: "no-touch" technique.

BACKGROUND: Aortic valve replacement or repair becomes a high-risk procedure in patients in whom the ascending aorta cannot be clamped either because of extensive calcification and risk of cerebral embolus or because of extensive adhesions precluding safe dissection and clamping. METHODS: We report the results of aortic valve replacement or repair with deep hypothermic circulatory arrest in 3 patients. Techniques to improve results include routine use of epiaortic and transesophageal echocardiography, avoidance of manipulation of the ascending aorta until the circulation is arrested, avoidance of antegrade cardioplegia, routine use of retrograde cardioplegia and retrograde cerebral perfusion, when feasible, and minimal aortotomy (just enough to excise and replace or repair the valve). RESULTS: Operations were accomplished in approximately 1 hour each with minimal manipulation of the aorta, thus minimizing aortic trauma and subsequent risk of cerebral embolus. Each patient had an unremarkable recovery without neurologic complications. CONCLUSIONS: Aortic valve replacement or repair using the "no-touch" technique and deep hypothermic circulatory arrest is the preferred method when dealing with the porcelain or unclampable aorta.

Aged↗
PubMed1998

Complete reversal of ischemic wall motion abnormalities by combined use of gene therapy with transmyocardial laser revascularization.

INTRODUCTION: Transmyocardial laser revascularization is believed to induce an angiogenic response within ischemic myocardium. We evaluated transgene expression in the setting of transmyocardial laser revascularization and hypothesized that intramyocardial injection of plasmid DNA encoding the gene for vascular endothelial growth factor could enhance the revascularization achieved by transmyocardial laser revascularization, resulting in improved cardiac function. METHODS: Ten Yorkshire pigs had carbon dioxide-transmyocardial laser revascularization or acupuncture sites with injections of an expression plasmid encoding the gene for beta-galactosidase with or without HVJ-liposomes. Three days after transduction, transgene expression was determined by enzyme-linked immunosorbent assay. Six weeks after placement of a constrictor on the left circumflex artery, 29 pigs were randomized to ischemic controls (n = 5), transmyocardial laser revascularization (n = 4), transmyocardial laser revascularization with expression plasmid beta-galactosidase injections (n = 5), expression plasmid-vascular endothelial growth factor injections (n = 4), or transmyocardial laser revascularization with expression plasmid-vascular endothelial growth factor (n = 5) and harvested 6 weeks after therapy. Six transmyocardial laser revascularization pigs had either expression plasmid beta-galactosidase or expression plasmid-vascular endothelial growth factor injections and were harvested at 2 weeks. Normal pigs (n = 5) were included for comparison. Left ventricular free wall motion was assessed by a cardiologist in a blinded manner. RESULTS: Transgene expression did not vary significantly with or without HVJ-liposomes in transfected transmyocardial laser revascularization myocardium. However, expression was detected in 56 of 60 (93%) transmyocardial laser revascularization-transfected sites, but in only 10 of 20 (50%) non-transmyocardial laser revascularization sites (P < .001). All (5 of 5 hearts) of the transmyocardial laser revascularization-vascular endothelial growth factor treated hearts displayed no evidence of wall motion abnormalities. Only these hearts had a statistically significantly different rate of wall motion abnormality compared with ischemic controls (P = .004). CONCLUSION: Transfection efficiency was improved with the use of transmyocardial laser revascularization. Wall motion abnormalities were completely reversed within 6 weeks after transmyocardial laser revascularization with the direct injection of an expression plasmid encoding vascular endothelial growth factor.

Animals↗
PubMed1998

Techniques and results of direct-access minimally invasive mitral valve surgery: a paradigm for the future.

OBJECTIVES: Our objective was to determine whether direct-access minimally invasive mitral valve surgery can improve recovery and cost while maintaining the efficacy of conventional surgery. METHODS: Minimally invasive mitral valve operations were performed on 106 patients, 58% male, average age 58.1 years, with good ventricular function. Ninety underwent repair of a regurgitant, myxomatous valve, and 16 underwent mitral valvuloplasty for prematurely calcified mitral stenosis. The valve was approached with standard instruments through a 5- to 8-cm right parasternal incision. Eighty-five had open femoral artery-femoral vein cannulation, but this technique has recently been replaced by direct cannulation of the aorta and percutaneous cannulation of the femoral vein for most patients. RESULTS: There were no operative deaths. The mean mitral regurgitation score (0-4) decreased from 3.7 to 0.7 after the operation. Although ischemic and bypass times were increased, postoperative recovery was accelerated. Ventilatory support time, intensive care unit stay, hospital stay, need for rehabilitation, and return to "normal activities" all improved. Hospital charges, pain medications, and blood transfusions were also reduced. New atrial fibrillation contributed significantly to increased length of stay and charges. There were no deep wound infections. Other complications included re-exploration for bleeding (n = 1), transient ischemic attacks (n = 2), stroke (n = 1), femoral artery injury (n = 5), pseudoaneurysm (n = 2), and antegrade dissection of the ascending aorta (n = 1). Two patients died and 1 required reoperation during a mean follow-up of 8.8 months. CONCLUSIONS: Direct-access minimally invasive mitral valve surgery can accelerate recovery, decrease charges, and decrease pain, while maintaining overall surgical efficacy. It has become our standard approach for isolated primary mitral valve operations.

Adult↗
PubMed1997

Thoracoscopic transmyocardial laser revascularization.

BACKGROUND: Transmyocardial laser revascularization is a promising surgical technique used to treat nonreconstructable ischemic heart disease. Recent clinical data show that this technique improves the regional perfusion of ischemic myocardium and reduces angina. Presently, transmyocardial laser revascularization requires an open, lateral thoracotomy. We report here the use of thoracoscopic techniques to perform transmyocardial laser revascularization in a closed chest fashion. METHODS: Five Yorkshire farm pigs underwent left chest thoracoscopic exploration and pericardiotomy. A specialized laser handpiece then was introduced into the chest and thoracoscopic transmyocardial laser revascularization was performed (one channel per square centimeter) using an 800-W CO2 laser. RESULTS: Video analysis and gross pathology revealed that the anatomic area accessible to thoracoscopic transmyocardial laser revascularization included the entire left ventricular free wall distributions of the left anterior descending, left circumflex, and posterior descending arteries, from base to apex. Standard hematoxylin and eosin staining confirmed the creation of complete and patent 1-mm-diameter transmural channels throughout these distributions. CONCLUSION: We have shown that transmyocardial laser revascularization can be performed effectively and safely by thoracoscopy, and that this less invasive technique may reduce morbidity and provide a more cost-effective alternative therapy for nonreconstructable ischemic heart disease.

Animals↗
PubMed1997

Right latissimus dorsi cardiomyoplasty improves left ventricular energetics.

BACKGROUND: The mechanism by which cardiomyoplasty appears to enhance left ventricular (LV) function is not well understood. We applied the time-varying elastance model to study the effect of cardiomyoplasty on LV function, ventriculovascular coupling, and LV energetics in an acute canine model. METHODS: Right latissimus dorsi cardiomyoplasty was performed in 5 dogs. The end-systolic pressure-volume relation was generated by using brief caval occlusions. End-systolic elastance, effective arterial elastance, stroke work, internal work, total mechanical work, and stroke work efficiency (stroke work/total mechanical work) were calculated from these pressure-volume data. Myocardial oxygen consumption and overall mechanical efficiency (stroke work/myocardial oxygen consumption) were predicted using the myocardial oxygen consumption-total mechanical work relation. RESULTS: Skeletal muscle contraction significantly increased end-systolic elastance, an index of contractility. Although stroke work did not change significantly, the increase in end-systolic elastance led to a 29% decrease in total mechanical work, a 50% decrease in internal work, and an increase in stroke work efficiency from 53% to 66%. This was consistent with the observed 29% decrease in effective arterial elastance/end-systolic elastance, an indicator of ventriculovascular coupling that is related inversely to stroke work efficiency. Predicted myocardial oxygen consumption decreased by at least 22%, and predicted overall mechanical efficiency increased at a minimum from 16.1% to 18.4%. CONCLUSIONS: These results support the theory that cardiomyoplasty unloads the LV by decreasing LV volumes and increasing contractility. These effects appear to improve LV energetics by decreasing total mechanical work without significantly affecting stroke work, resulting in improved stroke work efficiency. The decrease in total mechanical work strongly suggests a decrease in myocardial oxygen consumption and an increase in overall mechanical efficiency.

Animals↗
PubMed1997

Axilloaxillary cardiopulmonary bypass: a practical alternative to femorofemoral bypass.

BACKGROUND: Peripheral arterial and venous cannulation for cardiopulmonary bypass is used increasingly for patients undergoing minimally invasive cardiac operations, complex reoperations, or repair of aortic dissection or aneurysm, and for patients with extensive arteriosclerotic aortic disease in whom aortic cannulation is a prohibitive embolic risk. The common femoral artery and vein are most commonly used for peripheral cannulation, but these sites may be predisposed to complications, primarily because the femoral vessels are commonly involved with arteriosclerotic disease. We have recently begun to use the axillary artery and axillary vein as alternative cannulation sites, achieving full cardiopulmonary bypass, providing antegrade aortic flow, and avoiding many of the complications associated with other sites. METHODS: Seven patients with peripheral vascular or aortic disease, or both, prohibiting safe aortic or femoral cannulation underwent cardiopulmonary bypass through axillary artery and axillary vein cannulation, approached through a small single subclavicular incision. RESULTS: All patients were successfully cannulated and axilloaxillary cardiopulmonary bypass was possible without the need for additional cannulas. All axillary vessels were closed primarily without complication. CONCLUSION: For an expanding population of patients with peripheral vascular and aortic disease, axilloaxillary bypass is a safe and practical alternative to aortic or femoral cannulation.

Aged↗
PubMed1997

Reducing costs and length of stay and improving efficiency and quality of care in cardiac surgery.

BACKGROUND: The present era of health care places major emphasis on significantly reducing cost and resource utilization while maintaining quality of care and patient satisfaction. Clinicians are being challenged to achieve this within the framework of a patient subset that is increasing in severity of disease and risk-adjusted mortality. The Brigham and Women's Cardiac Surgical Services Management Group was formed in 1987 to help accomplish these goals. METHODS: The principles we have followed involve protocols and people. The multidisciplinary group includes the chiefs of cardiac surgery and anesthesia, chief residents, physician assistants, perfusionists, intensive care unit nursing personnel, and case managers. Weekly meetings address every aspect of problems arising in the cardiac surgical service; separate weekly morbidity and mortality conferences are held. The Care Coordination Team establishes and monitors clinical pathways and recommends ways of improving all aspects of the service through a process of daily review on an individual patient basis. RESULTS: The volume of cardiac surgery at Brigham and Women's Hospital has increased steadily. The length of stay overall has decreased about 15%, and similarly, cost and total charges have also decreased. In addition, patient satisfaction has increased to a level of about 95%. CONCLUSIONS: The goals of cost-containment with improved patient care and outcome are possible through the collaborative efforts of representatives of all the personnel involved in cardiac care, as well as leadership by the surgical faculty.

Administrative Personnel↗
PubMed1997

Transmyocardial laser revascularization: results of a multicenter trial with transmyocardial laser revascularization used as sole therapy for end-stage coronary artery disease.

BACKGROUND: Transmyocardial laser revascularization was used as the sole therapy for patients with ischemic heart disease not amenable to percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. This technique uses a carbon dioxide laser to create transmyocardial channels for direct perfusion of the ischemic heart. METHODS: Since 1992, 200 patients, at eight hospitals in the United States, have undergone transmyocardial laser revascularization. The patients have a combined 1560 months of follow-up for an average of 10 +/- 3 months per patient. Their age was 63 +/- 10 years and their ejection fraction was 47% +/- 12%. Eighty-two percent had at least one previous bypass graft operation and 38% had a prior angioplasty. Preoperatively, the patients underwent nuclear single photon emission computed tomography perfusion scans to identify the extent and severity of their ischemia. These scans were repeated at 3, 6, and 12 months. Angina class, admissions for angina, and medications were recorded. RESULTS: The perioperative mortality was 9%. Angina class decreased significantly from before treatment to 3, 6, and 12 months (p < 0.001). Likewise, there was a significant decrease in the number of perfusion defects in the treated left ventricular free wall. Concomitantly, there was a significant decrease in the number of admissions for angina in the year after the procedure when compared with the year before treatment (2.5 vs 0.5 admissions per patient-year). CONCLUSION: These combined results indicate that transmyocardial laser revascularization provides angina relief, decreases hospital admissions, and improves perfusion in patients with severe coronary artery disease.

Adult↗
PubMed1997

Minimally invasive cardiac valve surgery improves patient satisfaction while reducing costs of cardiac valve replacement and repair.

OBJECTIVE: This study compares the quality of valve replacement and repair performed through minimally invasive incisions as compared to the standard operation for aortic and mitral valve replacement. SUMMARY BACKGROUND DATA: With the advent of minimally invasive laparoscopic approaches to orthopedic surgery, urology, general surgery, and thoracic surgery, it now is apparent that standard cardiac valve operations can be performed through very small incisions with similar approaches. METHODS: Eighty-four patients underwent minimally invasive aortic (n = 41) and minimally invasive mitral valve repair and replacement (n = 43) between July 1996 and April 1997. Demographics, procedures, operative techniques, and postoperative morbidity and mortality were calculated, and a subset of the first 50 patients was compared to a 50-patient cohort who underwent the same operation through a conventional median sternotomy. Demographics, postoperative morbidity and mortality, patient satisfaction, and charges were compared. RESULTS: Of the 84 patients, there were 2 operative mortalities both in class IV aortic patients from multisystem organ failure. There was no operative mortality in the patients undergoing mitral valve replacement or repair. The operations were carried out with the same accuracy and attention to detail as with the conventional operation. There was minimal postoperative bleeding, cerebral vascular accidents, or other major morbidity. Groin cannulation complications primarily were related to atherosclerotic femoral arteries. A comparison of the minimally invasive to the conventional group, although operative time and ischemia time was higher in minimally invasive group, the requirement for erythrocytes was significantly less, patient satisfaction was significantly greater, and charges were approximately 20% less than those in the conventional group. CONCLUSIONS: Minimally invasive aortic and mitral valve surgery in patients without coronary disease can be done safely and accurately through small incisions. Patient satisfaction is up, return to normality is higher, and requirement for postrehabilitation services is less. In addition, the charges are approximately 20% less. These results serve as a paradigm for the future in terms of valve surgery in the managed care environment.

Adult↗
PubMed1997

Minimally invasive aortic valve replacement.

Aortic valve replacement has proven reliable, relieves life-threatening symptoms, and improves long-term survival of patients with aortic stenosis and aortic regurgitation. Minimally invasive aortic valve replacement uses small incisions; reduces exposure of the patient to surgical trauma, blood utilization, and operative dissection; although still using cardiopulmonary bypass and achieving the same general quality as with the open operation. Early and medium term results for minimally invasive aortic valve replacement approaches show a reduction in pain, improved patient satisfaction, and improved mobility and return to full-time activity. Concomitantly, there should be decreased cost and a decreased reliance on post-hospital rehabilitation.

Adult↗
PubMed1996

Decreased myocardial oxygen consumption indices in dynamic cardiomyoplasty.

BACKGROUND: To investigate the theory of decreased myocardial oxygen consumption (MVo2) in dynamic cardiomyoplasty (DCM), previous studies have calculated indices of MVo2 in DCM. These previous studies, however, used left ventricular pressure in formulas that assumed the assumed the heart to be in its native state, with the reference pressure at the epicardium assumed to be atmospheric. In DCM, however, the reference pressure at the epicardium is no longer atmospheric but rather is the compressive pressure generated by the latissimus dorsi (LD). We therefore used the transmural myocardial pressure, Pt, to calculate indices of MVo2 in DCM. METHODS AND RESULTS: A half-ellipsoidal, fluid-filled balloon was interposed between the LD and myocardium in a balloon-mediated cardiomyoplasty procedure in five goats. With commonly used LD stimulation parameters, Pt was calculated as left ventricular pressure minus balloon luminal pressure. Using Pt, the transmural tension time index (TtTI) and transmural pressure volume area (PtVA) were calculated. In another series of four goats, LD stimulation parameters were optimized and the TtTI and PtVA recalculated. With standard LD stimulation parameters, the TtTI decreased by 48%, from 15.8 to 8.2 mm Hg.s, and the PtVA by 21%, from 775 to 612 mm Hg.mL, as the LD was stimulated to contract. When the optimized parameters were used, the TtTI decreased by 45%, from 11.2 to 6.2 mm Hg.s, and the PtVA by 33%, from 1984 to 1371 mm Hg.mL. CONCLUSIONS: Our results suggest that DCM with a fluid-filled balloon decreases MVo2 as the LD contracts and that LD stimulation parameters have a determining effect on this benefit.

Animals↗
PubMed1996

Predictors of atrial fibrillation after coronary artery surgery. Current trends and impact on hospital resources.

BACKGROUND: Atrial fibrillation (AF) after coronary artery bypass surgery (CABG) is the most common sustained arrhythmia. Its pathophysiology is unclear, and its prevention and management remain suboptimal. The aim of this prospective study was to determine the current incidence of AF, identify its clinical predictors, and examine its impact on resource utilization. METHODS AND RESULTS: Over a 12-month period ending July 31, 1994, a CABG procedure was performed on 570 consecutive patients (age range, 32 to 87 years; median age, 67 years; 232 [41%] were > or = 70 years; 175 [31%] were women; 173 [30%] were diabetics; 364 [65%] required nonelective surgery; 86 [15%] had had a prior CABG; and 86 [15%] had had prior percutaneous transluminal coronary angioplasty). AF occurred in 189 patients (33%). The median age for patients with AF was 71 years compared with 66 for patients without (P = .0001). Multivariate logistic regression analysis (odds ratio, +/- 95% CI, P value) was used to identify the following independent predictors of postoperative AF: increasing age (age 70 to 80 years [OR = 2; CI, 1.3 to 3; P = .002], age > 80 years [OR = 3; CI, 1.6 to 5.8; P = .0007]), male gender (OR = 1.7; CI, 1.1 to 2.7; P = .01), hypertension (OR = 1.6; CI, 1.0 to 2.3; P = .03), need for an intraoperative intraaortic balloon pump (OR = 3.5; CI, 1.2 to 10.9; P = .03), postoperative pneumonia (OR = 3.9; CI, 1.3 to 11.5; P = .01), ventilation for > 24 hours (OR = 2; CI, 1.3 to 3.2; P = .003), and return to the intensive care unit (OR = 3.2; CI, 1.1 to 8.8; P = .03). The mean length of hospital stay after surgery was 15.3 +/- 28.6 days for patients with AF compared with 9.3 +/- 19.6 days for patients without AF (P = .001). The adjusted length of hospital stay attributable to AF was 4.9 days, corresponding to > or = $10 055 in hospital charges. CONCLUSIONS: AF remains the most common complication after CABG and consequently is a drain on hospital resources. Concerted efforts to reduce the incidence of AF and the associated increased length of stay would result in substantial cost saving and decrease patient morbidity.

Adult↗
PubMed1996

Long-term follow-up after surgical repair of ostium primum atrial septal defects in adults.

OBJECTIVES: We sought to determine the long-term survival rates and defect-related morbidity of adult patients who undergo surgical repair of an ostium primum atrial septal defect. BACKGROUND: The natural history of patients undergoing such surgical repair in adulthood remains unclear. METHODS: We followed up 33 patients who underwent surgical correction of an ostium primum atrial septal defect at our institution at a mean age of 42 years (range 20 to 73); 12 of these patients were > 50 years old at the time of operation. Four patients had moderate preoperative exercise incapacity (New York Heart Association functional class > II) and six had atrial fibrillation. Nine and four patients, respectively, had a preoperative mean pulmonary artery pressure > 25 mm Hg or pulmonary vascular resistance > 4 Wood U. Autologous pericardium was used to patch the defect in 30 patients (91%). Mitral valvuloplasty, consisting of cleft repair (n = 10), and mitral valve replacement (n = 2) were performed selectively. RESULTS: There were no operative deaths. At a mean follow-up interval of 5.3 years (range 1 to 18.2), all 28 surviving patients are free of exercise limitation (functional class 1). Late postoperative deaths occurred in five patients (15%) and were related to myocardial infarction, stroke, hepatic failure, renal failure or sepsis. Reoperation within the 1st postoperative year was required in two patients (6%) because of a residual ostium primum defect in one and severe mitral regurgitation in the other. The presence of advanced age at operation, symptoms, atrial arrhythmias, mitral regurgitation or moderately increased pulmonary vascular resistance did not predict late postoperative mortality, complications or functional capacity. CONCLUSIONS: An ostium primum defect can be repaired in adult patients with the expectation of excellent long-term results, independent of age at operation and preoperative mitral valve function and despite the presence of atrial fibrillation or moderately elevated pulmonary vascular resistance.

Adult↗