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Biomedical subjects

R H Breyer

Publications and source records attributed to R H Breyer.

At least 55 records · Page 3Linked to original sources
PubMed1983

Is a left ventricular vent necessary for coronary artery bypass operations performed with cardioplegic arrest?

The need for ventricular venting with hypothermic cardioplegic arrest is controversial. We report an evaluation of the need for left ventricular venting in a canine model that closely simulates conditions during routine coronary artery bypass grafting (CABG). Thirty-five dogs were placed on cardiopulmonary bypass for 60 minutes of hypothermic cardioplegic arrest (18 vented, 17 nonvented) and then reperfused for 30 minutes. Myocardial temperature and left atrial pressure (LAP) were recorded continuously. Before and 30 minutes after hypothermic cardioplegic arrest, left ventricular function curves were generated (six vented, six nonvented), and biopsy specimens of the left ventricle were taken for adenosine triphosphate (ATP) determinations (11 vented, 10 nonvented) and semiquantitative grading of mitochondrial ultrastructure (six vented, six nonvented). LAP in nonvented dogs was 7.4 mm Hg during hypothermic cardioplegic arrest and 5.0 mm Hg during reperfusion. Temperature during hypothermic cardioplegic arrest was 12.3 degrees C in vented dogs and 11.3 degrees C in nonvented dogs (p = 0.5). There were no differences in left ventricular function or preservation of mitochondrial ultrastructure between vented and nonvented dogs. ATP after hypothermic cardioplegic arrest was 96.6% of control (4.30 microM/gm) in vented dogs and 94.6% (4.37 microM/gm) in nonvented dogs (p = 0.7). The absence of left ventricular venting did not lead to ventricular distention or more rapid rewarming. These data in vented dogs and nonvented dogs strongly support the belief that left ventricular venting is not necessary during routine CABG.

Adenosine Triphosphate↗
PubMed1982

Delayed left ventricular rupture secondary to transatrial left ventricular vent.

The cases of 2 patients with delayed ventricular rupture secondary to ventricular venting through the left atrium during myocardial revascularization are reported. Both patients were weaned from cardiopulmonary bypass without difficulty and were transported to the intensive care unit in good condition. Rupture occurred in one patient two hours later and in the other, approximately twelve hours postoperatively; both patients died. Both patients were short in stature, and it is possible that advancing the catheter to the first guide mark left the tip unusually close to the ventricular apex. As the catheter cooled and hardened and as the heart was retracted, the catheter may have been pushed against the apical endocardium, thereby producing undetectable subendocardial damage. Our experience with these 2 patients has led us to become more selective in venting for coronary bypass operations. When venting is necessary, we insert the catheter so that its tip barely enters the ventricle.

Aged↗
PubMed1982

Malignant fibrous histiocytoma of the mediastinum and lung: a report of three cases.

One case of primary malignant fibrous histiocytoma of the lung and two cases of that tumor in the mediastinum are reported. Primary malignant fibrous histiocytoma is rare in those areas, appearing more commonly in deep fascia and skeletal muscles of the extremities and torso and in the retroperitoneum. Most of the tumors contain both fibroblast-like and histiocyte-like cells; some contain pleomorphic giant cells and inflammatory cells. They are often confused with other sarcomas, and their true biologic potential is not clearly defined. Radiation appears to be a very useful adjunct to surgical therapy and was used in the cases reported here.

Female↗
PubMed1982

Clinical spectrum of blunt tracheobronchial disruption illustrated by seven cases.

Tracheobronchial disruption resulting from blunt trauma is unusual, but when it does occur it can have serious immediate and delayed consequences. A high index of suspicion for this injury and an awareness of the variety of clinical, radiographic, and bronchoscopic presentations are the key elements in diagnosis. Our experience with seven patients with blunt tracheobronchial trauma seen from 1972 through 1980 is reviewed. Emphasis is placed on the importance of early diagnosis to avoid the complications associated with delayed repair.

Accidents, Traffic↗
PubMed1981

Thoracotomy in patients over age seventy years: ten-year experience.

Recent reports have demonstrated satisfactory long-term survival following pulmonary resection in the elderly. However, the high operative risk commonly cited in patients over 70 years of age has led some authors to conclude that advanced age is a contraindication to pulmonary resection. During 1969 to 1978, 218 thoracotomies were performed in patients over the age of 70 years. Operations performed include 175 pulmonary resections and 43 miscellaneous thoracic surgical procedures. Primary or metastatic cancer was the indication for 174 operations (pulmonary resection, 150 cases; exploration and biopsy, 16 cases; pleurectomy, eight cases). One hundred thirty-seven patients (63%) had a benign course, whereas 74 patients experienced a total of 83 complications. Minor complications of atrial fibrillation, air leaks persisting for 7 to 14 days, and successfully managed retention of secretions were seen in 34 patients (16%). Nonfatal major complications were predominantly cardiac and respiratory in nature and occurred in 40 patients (18%). The overall hospital mortality was 3% (seven patients). Lung-sparing procedures were utilized whenever possible among the 150 patients undergoing pulmonary resection for carcinoma (sleeve lobectomy, 13 cases; segmental resection, 52 cases; wedge resection, 12 cases). The hospital mortality of 4% among these 150 patients was significantly lower (p < 0.001) than the 17% mortality among 308 elderly patients compiled from five series reported by other centers between 1973 and 1978. Long-term follow-up was obtained in 129 of the 139 (93%) available patients surviving pulmonary resection for cancer. The overall 5 year survival rate is 27%, ranging from 13% for patients having pneumonectomy to 42% for those having segmental resection.

Age Factors↗
PubMed1980

Mucoepidermoid carcinoma of the trachea and bronchus: the case for conservative resection.

We report our experience with 5 patients with mucoepidermoid carcinoma treated by conservative resection, and review the literature on the 62 patients previously reported. A visual bronchoscopic diagnosis of adenoma was made in all 5 current patients. Bronchoscopic biopsy was performed in 4 and provided an accurate histological diagnosis in each. Conservative resection was accomplished with bronchoplastic techniques in 4 patients: sleeve lobectomy, 2; lobectomy with plastic bronchial closure, 1; and segmental tracheal resection, 1. The other patient underwent conventional lobectomy. All 5 patients are alive and free from disease 4 to 15 years following operation. The recently demonstrated correlation between histological grading and clinical behavior allows relatively benign variants of mucoepidermoid tumors to be accurately identified by bronchoscopic biopsy prior to thoracotomy. Because these tumors have a propensity to originate centrally in the tracheobronchial tree, bronchoplastic procedures frequently are required in order to accomplish tumor extirpation with limited pulmonary resection.

Adenoma↗
PubMed1978

Prosthetic-valve endocarditis due to Listeria monocytogenes.

Clinical and necropsy observations in the case of a patient with prosthetic-valve endocarditis due to Listeria monocytogenes are presented. Although rare cases of L. monocytogenes infection of natural cardiac valves have been reported, this represents the first known case of infection of a prosthetic cardiac valve by this organism.

Aortic Valve↗
PubMed1977

The effects of isoproterenol and dopamine on regional myocardial blood flow after stenosis of circumflex coronary artery.

The effects of isoproterenol and dopamine on regional myocardial blood flow were studied in 10 open-chest dogs after acute stenosis of the proximal circumflex coronary artery. Blood flow was determined by the radioactive microsphere technique. Isoproterenol led to a homogenous increase in blood flow in the normal myocardium. In the myocardium with compromised coronary blood flow, isoproterenol led to a relative subendocardial ischemia. This occurred despite increased aortic flow and peak left ventricular dp/dt. Dopamine also increased aortic flow and peak left ventricular dp/dt, but it did not cause regional myocardial ischemia. The findings suggest that dopamine is the preferable inotropic agent in managing low cardiac output in patients with significant coronary artery disease.

Animals↗
PubMed1976

Tricuspid regurgitation. A comparison of nonoperative management, tricuspid annuloplasty, and tricuspid valve replacement.

The best means of managing tricuspid regurgitation associated with mitral or mitral and aortic valve disease is still to be determined. During the period 1972 to 1974, we treated 76 patients who had tricuspid regurgitation along with associated valvular dysfunction. Patients with mold regurgitation were treated conservatively, those with moderate regurgation underwent annuloplasty, and those with severe regurgitation had tricuspid valve replacement. We found the results to be less satisfactory in the group treated by annuloplasty than in the other two groups. We still manage conservatively those patients with mild regurgitation, but we believe it appropriate to replace the valve in an increasing number of subjects who have tricuspid regurgitation of moderate severity.

Animals↗
PubMed1976

Histologic changes in saphenous vein aorta-coronary bypass grafts. The effect of the angle of the aortic anastomosis.

Thirteen dogs were subjected to bypass grafting from the aorta to the left circumflex coronary artery with the saphenous vein to determine whether the angle of insertion of the saphenous vein into the aorta influences the functional and histologic fate of the grafts. The angle of the aortic anastomosis was obtuse in 6 dogs, acute in 5, and perpendicular in 2. Histologic examination of all 13 grafts 6 to 19 months (mean 9.4) postoperatively showed fibrous intimal proliferative lesions of variable severity along the entire length of the grafts, occasionally with extension into the native coronary arteries. Loss of medical smooth muscle and adventitial fibrosis also occurred in all 13 grafts. The extent and severity of these changes, however, were not related to the angle aortic anastomosis.

Animals↗
PubMedDate not supplied

Enhanced myocardial preservation by nicotinic acid, an antilipolytic compound: mechanism of action.

The cardioprotective effects of an antilipolytic compound, nicotinic acid, on arrested-reperfused myocardium were investigated in the isolated in situ pig heart preparation. Hearts were preperfused for 15 min in the presence of (5-3H)-glucose and (U-14C)-palmitic acid. Half of the hearts were then perfused with 0.08 mM nicotinic acid for an additional 15-min period, while the remaining control hearts received unmodified perfusion. Arrest was then induced in all animals for 2 h using hypothermic K+ cardioplegia, followed by 60 min of normothermic reperfusion. In control hearts, there were significantly greater levels of long-chain acyl Co-A and acyl carnitine and lower levels of membrane phospholipids than in the nicotinic acid group. While nicotinic acid inhibited beta-oxidation during pre-ischemia and reperfusion, it also prevented the degradation of membrane phospholipids. The net result was a reduction of free fatty acid accumulation during arrest and reperfusion in the nicotinic acid group. Glycolysis, as reflected in 3H2O production, was significantly increased by nicotinic acid administration. In the control heart as compared to the nicotinic acid group, the incorporation of 14C-label from palmitate into triglyceride and cholesterol during arrest was enhanced, while incorporation into phospholipids was depressed. The cardioprotective effects of nicotinic acid were demonstrated by decreased release of creatine kinase and improved coronary blood flow, and cardiac contractility in the reperfused myocardium supplemented with nicotinic acid compared to the control group. These results suggest that nicotinic acid significantly protects the arrested-reperfused myocardium by a) preventing elevation of myocardial fatty acid levels, b) stimulating glycolysis by limiting fatty acid oxidation, c) inhibiting degradation of membrane phospholipids, and d) preventing accumulation of fatty acid metabolites with harmful detergent properties.

Animals↗
PubMedDate not supplied

Role of a nonsteroidal anti-inflammatory agent, ibuprofen, in coronary revascularization after acute myocardial infarction.

The efficacy of using a nonsteroidal anti-inflammatory agent such as ibuprofen for the salvage of ischemic and reperfused myocardium was investigated by examining its ability to improve global and regional functions as well as to preserve high-energy phosphate compounds and inhibit creatine kinase release from an isolated in-situ pig heart subjected to 1 h of normothermic regional ischemia followed by 1 h of global hypothermic arrest and 1 h of normothermic reperfusion. Preperfusion of the heart for 15 min prior to ischemic insult with 50 microM ibuprofen failed to mitigate the myocardial reperfusion injury. Ibuprofen, however, functioned as an anti-inflammatory agent, as judged by its ability to inhibit the influx of indium-111-labeled polymorphonuclear leukocytes and chromium-51 (51Cr)-labeled platelets into the ischemic and reperfused heart. It also blocked the cyclooxygenase pathway, as evidenced by the significant reduction of 6-keto-prostaglandin F1 alpha and thromboxane B2 concentrations in the perfusate. Inhibition of cyclooxygenase resulted in increased accumulation of nonesterified fatty acids, particularly arachidonic acid, in the heart. These results suggest that although ibuprofen can inhibit polymorphonuclear leukocyte and platelet influx into the ischemic and reperfused heart, it causes further damage to the already ischemic heart by reducing prostacyclin concentration and increasing free fatty acids in the heart.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Developmental profiles of protective mechanisms of heart against peroxidative injury.

The developmental profiles of the protective mechanisms of heart against peroxidative injury during neonatal growth was examined in the pigs of three different age groups. Lipid peroxidation expressed in terms of malonaldehyde formation was considerably higher in the pig hearts of the 8-10 day age group compared to that either by newborn or adult age groups. The four principal antioxidative enzymes, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase (G6PD), were enhanced during early neonatal growth and, with the exception of G6PD, all other enzymes were further enhanced during further growth to adulthood. G6PD activity dropped significantly in adult heart. The phospholipid contents of myocardial membrane between newborn and week-old pigs did not vary significantly. Total phospholipids and phosphatidylcholine contents were significantly higher in adult heart compared to those in neonatal heart. The enzymes of phospholipid synthesis and degradation, fatty acyl CoA synthetase (FACS), phospholipase A2 (PLA2), lysophospholipase (LPL), and lysophophatidylcholine acyltransferase (LPCAT) increased during early neonatal growth. During further growth to adulthood, FACS decreased, PLA2 did not change, whereas both LPL and LPCAT increased significantly. Analysis of free fatty acids showed that palmitic and stearic acids decreased during the first week of growth, but increased during further growth to adulthood. Oleic acid did not change with aging, but arachidonic acid dropped in adult heart compared to that in neonatal heart. Linoleic, palmitoleic and free fatty acids increased dramatically during the first week of neonatal growth, but dropped thereafter. These results suggest that the unusual peroxidative status of the week-old pig heart is related to the presence of high concentrations of polyunsaturated fatty acids in the membrane phospholipids and not with the antioxidative defense system.

Aging↗
PubMedDate not supplied

Pathophysiology of superoxide radical as potential mediator of reperfusion injury in pig heart.

The role of oxygen-derived free radicals in myocardial reperfusion injury was studied using the isolated in situ pig heart model. The free radical scavengers, superoxide dismutase (SOD) and catalase, protected the ischemic pig heart subjected to one hour of normothermic regional ischemia followed by one hour of global hypothermic arrest and one hour normothermic reperfusion. A significant increase in thiobarbituric acid reactive material and oxidized glutathione appeared in the perfusate demonstrating free radical-mediated lipid peroxidation during reperfusion, and this was prevented by the addition of SOD plus catalase. The values of three important antioxidative enzymes, SOD, catalase, and glutathione peroxidase, showed reduced activities after 2 hours of ischemia. These values did not change significantly after 60 minutes of reperfusion following the 2 hours ischemic insult. The concentrations of high-energy phosphate compounds including creatine phosphate (CP), adenosine triphosphate (ATP), and total adenine nucleotide were reduced significantly during ischemia and reperfusion in hearts which were not protected by SOD and catalase. The plasma creatine phosphokinase levels were lowered appreciably as a result of SOD and catalase treatment. It may be concluded from these experiments that oxygen-derived free radicals are present during reperfusion and SOD and catalase play a significant role in the protection of ischemic myocardium from reperfusion injury.

Adenine Nucleotides↗
PubMedDate not supplied

Open mitral commissurotomy: long-term results with echocardiographic correlation.

Over 11 years, 91 patients with isolated mitral stenosis underwent open mitral commissurotomy. Twenty-nine were 50 or more years old; 15 had had prior commissurotomies. Four (4.4%) died perioperatively; 87 were followed for one to nine years (average: five years). Overall actuarial survival was 94% at 5 years. Sixty-nine patients (79%) were NYHA Functional Class (FC) I or II at latest follow-up. Arterial embolism occurred in five patients; 14 patients (16%) had a second valve operation. Patients who remain in FC I or II and who are free of embolism and reoperation are classified as complication-free. Actuarial analysis demonstrated 76% to be so classified at five years after operation. Actuarial curves show that age older than 40 years, sex, previous commissurotomy, and "radical" versus simple open mitral commissurotomy did not influence survival or the incidence of good results. Follow-up M-mode and 2D echocardiograms were obtained in 42 patients. The estimated mitral orifice accurately separated FC I patients (orifice equal to or larger than 2 cm2) from FC II and FC III patients (orifice smaller than 2 cm2), and showed that echocardiographic evidence of a 2 cm2 or larger mitral orifice correlates with a good result.

Adult↗
PubMedDate not supplied

Atrial septal defect: repair in patients over thirty-five years of age.

Fifty-eight patients over age 35 underwent repair of atrial septal defect. The operative mortality was zero for the seven N.Y.H.A. class I and 26 N.Y.H.A. class II patients. One of 16 class III patients and two of nine class IV patients died; consequently, overall hospital mortality was five percent. The operative mortality was not related to age or level of pulmonary hypertension. Long-term clinical improvement was documented in 75 percent of patients who had been symptomatic preoperatively. The suggestion in early reports that pulmonary hypertension, or age per se, many contraindicate repair of an ASD cannot be supported by our results.

Adult↗