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Biomedical subjects

R K Brawley

Publications and source records attributed to R K Brawley.

At least 37 records · Page 2Linked to original sources
PubMed1978

Autotransfusion of shed mediastinal blood after cardiac surgery: a prospective study.

In a randomized prospective study of patients having cardiac surgery, autologous blood collected from mediastinal tubes was autotransfused preferentially in 63 patients (ATS), whereas 51 patients received bank blood for transfusion (control). Comparison of the two groups showed no significant difference in regard to age, sex, operations performed, or total postoperative bleeding (ATS 813 +/- 121 ml. per square meter versus control 711 +/- 93 ml. per square meter; N.S.) Although mean postoperative blood replacement was similar in the two groups (ATS 4.3 +/- 0.6 units per patient versus control 4.8 +/- 0.6 units per patient), requirements for transfusion of stored bank blood were reduced by 50 percent in the ATS group (ATS 2.4 +/- 0.3 units per patient versus control 4.8 +/- 0.6 units per patient; p less than 0.005). Coagulation studies demonstrated that this blood was defibrinogenated; yet it contains significantly more platelets and clotting factors than does bank blood. In this study, autotransfusion of shed mediastinal blood was safe and simple. It significantly reduced bank blood requirements and resulted in substantial financial savings for the patients and the hospital.

Blood Cell Count↗
PubMed1977

The heparin-coated vascular shunt for thoracic aortic and great vessel procedures: a ten-year experience.

From 1966 to 1976 a flexible, heparin-coated shunt was used for operative procedures on the thoracic aorta and great vessels in 25 patients aged 15 to 78 years. Twenty patients had resection of aneurysms of the descending thoracic aorta. There was 1 death in 15 patients undergoing elective resection and 2 deaths (both from rupturing aneurysms) in 5 patients having emergency resection. The shunt was used in 5 patients who had procedures involving involving the great vessels. There have been no complications attributable to the shunt in either group. The advantages of this shunt include elimination of the need for systemic heparin, avoidance of hypertension during cross-clamping, and adequate perfusion of the distal cirulation without an interposed pump. Because of the ease of handling, low risk, and versatility, we consider the use of this shunt the preferred method for support in elective procedures of the thoracic aorta and great vessels.

Adolescent↗
PubMed1977

Effects of atrial pacing on regional myocardial gas tensions with critical coronary stenosis.

Changes in myocardial carbon dioxide (PmCO2) and oxygen tension (PmO2) measured by mass spectrometry have been shown to reflect quantitatively progressive degrees of regional myocardial ischemia associated with stepwise reduction in coronary blood flow. The present study utilized mass spectrometry to assess the severity of regional myocardial ischemia developing during atrial pacing in the presence of a flow-limiting proximal critical coronary artend subendocardial layers was measured by the radioactive microsphere technique. Application of a "critical stenosis" resulted in a 6-mmHg decrease in PmO2 and a 17-mmHg increase in PmCO2 in the region of the myocardium supplied by the stenosed vessel. The addition of atrial pacing resulted in a 3-mmHg further decrease in Pmo2 and a 40-mmHg further increase in PmCO2. In the region of myocardium supplied by the critically stenosed vessel MBF increased in the subepicardial layer, but decreased or remained unchanged in the subendocardial layer. The failure of myocardial blood flow to increase in deeper myocardial layers in response to the increased myocardial oxygen demand of atrial pacing would provide a mechanism for the development of subendocardial ischemia in the presence of a critical coronary stenosis.

Animals↗
PubMed1977

Occlusive changes at the coronary artery--bypass graft anastomosis. Morphologic study of 95 grafts.

Ninety-five bypass graft anastomoses in 52 patients dying up to 4 years after direct coronary revascularization were studied at autopsy by angiograms and serial histologic sectioning of the graft-artery anastomosis. When new coronary occlusions and narrowings occurred, they were adjacent to either the proximal or distal ends of the anastomosis and were due to compression or loss of circumference of the arterial lumen (40 per cent), thrombus formation (40 per cent), mural dissection of the coronary wall (8 per cent) or the combination of compression and thrombosis (12 per cent). Small coronary artery diameter, local atheromas, and extension of the arteriotomy into a branch vessel were significant factors predisposing to occlusive changes. The findings emphasize the importance of careful artery selection for bypass, the need to avoid local vascular disease and branch-points, and the technical difficulties encountered in the presence of local vascular lesions or small coronary arteries.

Adult↗
PubMed1977

Influence of coronary artery anatomy on survival following resection of left ventricular aneurysms and chronic infarcts.

Left ventricular (LV) aneurysms were resected in 27 patients for treatment of congestive heart failure and in five patients for treatment of ventricular arrhythmia. There were eight early (25 per cent) and five late (15 per cent) deaths. Preoperative hemodynamics including analysis of left ventriculograms in the right anterior oblique position did not consistently predict survival. In contrast, coronary artery anatomy appeared to influence the mortality rate strikingly in patients with congestive heart failure. The hospital mortality rate was 6 per cent and the late mortality rate was 13 per cent for 16 patients with one-or two-vessel coronary artery disease, but with unobstructed LV lateral wall blood supply. All but one of the survivors obtained a good late result. In nine patients with two-and three-vessel coronary artery disease and obstructed LV lateral wall blood supply there were six hospital deaths and two late deaths. It is concluded that the presence or absence of occlusive disease in the arteries supplying the LV lateral wall is an important determinant of the mortality rate associated with resection of anterior apical LV aneurysms in patients with severe congestive heart failure.

Animals↗
PubMed1977

Operative management of penetrating vascular injuries of the thoracic outlet.

A five year experience with 20 patients who had penetrating vascular injuries of the thoracic outlet was reviewed. A median sternotomy with extension into the right neck was used to explore six patients with right subclavian vascular injuries. With injuries to the origin of the left common carotid artery, repair was accomplished through a median sternotomy combined with a left anterior thoracotomy in one patient and through a left posterolateral thoracotomy in the other. Injury to the left subclavian vessels occurred in five patients and was exposed through a left anterolateral thoracotomy combined with a supraclavicular incision in four patients and through a supraclavicular incision with clavicular resection in one patient. Axillary vessel trauma generally was managed with an extrathoracic incision only. The two deaths in this series were due to postoperative respiratory complications (mortality rate of 10%). Twenty arteries were repaired and all were patent on follow-up examination. Associated neural and venous injury caused significant morbidity in 28% and 10% of patients, respectively. As a result of this experience we continue to recommend an extended median sternotomy for repair of right-sided cervicothoracic vascular injury. Anterior or posterolateral thoracotomy combined with a supraclavicular incision is advocated for trauma to left-sided vessels of the thoracic outlet. When possible, injured veins should be repaired rather than ligated.

Adolescent↗
PubMed1977

Regional ischemia distal to a critical coronary stenosis during prolonged fibrillation--improvement with pulsatile perfusion.

In a previous study from this laboratory, regional myocardial ischemia developed distal to a critical coronary stenosis in the fibrillating heart on cardiopulmonary bypass when myocardial perfusion was non-pulsatile. To assess the effect of pulsatile perfusion on the development of the fibrillation-induced ischemia, 10 dogs were placed on total cardiopulmonary bypass with the heart in the vented fibrillating state. A critical stenosis was applied to the left anterior descending artery (LAD). Pulsatile perfusion with a pulse pressure of 35 mm Hg and a pulse rate of 100/min was produced by a new method developed in this laboratory. During the 2 hours of bypass, ischemia in the LAD-supplied myocardium was assessed by changes in intramyocardial oxygen (PmO2) and carbon dioxide (PmCO2) tensions and by regional arterial-coronary venous lactate difference. With linear perfusion, regional ischemia in the LAD myocardium had been evidenced by a low PmO2 (8 +/- 3 mm Hg), a high PmCO2 (170 +/- 25 mm Hg) and regional lactate production (9.2 +/- 4.2 mg/100 ml). In contrast with pulsatile perfusion intramyocardial gas tensions remained stable during the 2 hours on bypass (PmO2 = 21 +/- 3 mm Hg, PmCO2 = 65 +/- 5 mm Hg, P less than 0.05 vs linear flow study) and lactate consumption was demonstrated (+17.7 +/- 2.9 mg/100 ml, P less than 0.001 vs linear flow group). With linear perfusion, myocardial blood flow to the LAD area had decreased 56 +/- 8% in the subendocardial layer and 46 +/- 7% in the subepicardial layer. In the dogs receiving pulsatile flow during bypass, regional LAD blood flow remained unchanged over the 2-hour bypass period and was significantly higher than the flow with linear flow (P less than 0.05). These data indicate that fibrillation-induced regional myocardial ischemia distal to a critical stenosis can be prevented by maintaining pulsatile perfusion during cardiopulmonary bypass.

Animals↗
PubMed1976

Permanent cardiac pacemakers in children: technical considerations.

Placement of permanent cardiac pacemakers in children presents technical problems that are not encountered in the adult. Problems unique to pacemaker implantation in children are related to the patient's size, the relative bulkiness of pulse generators, the lack of subcutaneous tissue, and the child's growth and long life expectancy. Based on our experience with implantation of 27 permanent cardiac pacemakers in 13 children, we have found that the use of small pulse generators, placement of epicardial leads, insertion of properitoneal pulse generators, and use of recharabeable pacemakers are satisfactory methods in children.

Adolescent↗
PubMed1976

Late cardiac tamponade: a potentially lethal complication of open-heart surgery.

Cardiac tamponade occurring late after open-heart surgery is a frequently fatal complication. Of the 13 cases previously reported in the literature, there were seven deaths. In this report, three additional patients with late cardiac tamponade successfully treated are presented. Postoperative anticoagulation with Coumadin appeared to contribute to this complication. Increased awareness of late cardiac tamponade allowing prompt recognition and immediate decompression of the pericardial sac should lower the high mortality rate previously associated with the condition.

Adult↗
PubMed1976

The influence of ventricular function on the results of aortic valve replacement for aortic stenosis.

Thirty-three patients who had aortic valve replacement (AVR) for isolated aortic stenosis (AS) were retrospectively evaluated to determine the influence of preoperative ventricular function on the results of operation. Patients were arbitrarily divided by ejection fraction (EF) into Group I having EF 0.46 or above and Group II having EF 0.45 or below. Group II had significantly lower mean EF and cardiac index and higher left ventricular end-diastolic volume index and end-diastolic pressure. There were two early and no late deaths in 21 Group I patients. There were no early and five late deaths in 12 Group II patients. All Group I survivors and six of 12 Group II patients were New York Heart Association (NYHA) functional Class I or II at follow-up evaluation. No preoperative hemodynamic index was predictive of which Group II patients would do well. Mortality was substantially higher in patients with severe preoperative disability. Early or late death occurred in five of 12 patients who were NYHA functional Class IV before operation but in only two of 21 patients who were functional Class II or III preoperatively. We conclude that patients with isolated AS and poor left ventricular function have a low hospital mortality but an increased risk of late death or poor functional result following AVR. Excellent functional results can be obtained after AVR in most patients with AS and good left ventricular function and approximately half of the patients with AS and poor left ventricular function.

Adult↗
PubMed1975

Current status of the Beall, Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter cardiac valve prostheses.

The Starr-Edwards ball valve prosthesis is generally the standard by which other cardiac valve substitutes are compared. This report reviews information pertaining to several prostheses--the Beall mitral valve and the Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter aortic and mitral valves--considered by some to have specific advantages over the Starr-Edwards valves. Hospital and late mortality rates after valve replacement are comparable for the four aortic valve prostheses reviewed and depend more on patient selection than on the specific prosthesis utilized. Extensive clinical experience with the Bjork-Shiley aortic valve indicates that this prosthesis offers hemodynamic advantages over ball valve prostheses, especially in patients with a small aortic root. Clinical experience with the Lillehei-Kaster pivoting disc prosthesis has been less extensive, but this model provides theoretical hemodynamic advantages similar to those of the Bjork-Shiley aortic valve prosthesis. Problems associated with cloth wear and the unexpectedly slow rate, in man, of tissue ingrowth into the fabric of the Braunwald-Cutter aortic valve prosthesis have been discouraging, although this prosthesis has been associated with a very low thromboembolic rate in patients receiving anticoagulant therapy. The Smeloff-Cutter aortic prosthesis is hemodynamically similar to the Starr-Edwards prosthesis and has been proved to be a reliable and durable aortic valve substitute over the past several years. Mortality after mitral valve replacement is also largely influenced by factors other than prosthetic valve design. On the basis of postoperative data, the five mitral valve prostheses reviewed do not appear to have substantial hemodynamic differences. For patients with a small left ventricular cavity the low profile prostheses, such as the Beall, Bjork-Shiley and Lillehei-Kaster, may be advantageous. Most available evidence indicates that patients receiving aortic or mitral valve prostheses should be given anticoagulant therapy postoperatively.

Anticoagulants↗
PubMed1975

The "angina-producing" myocardial segment: An approach to the interpretation of results of coronary bypass surgery.

The first 153 cases of saphenous vein aortocoronary bypass surgery performed at The Johns Hopkins Hospital were reviewed. Eighty-eight percent of the 140 late survivors reported significant symptomatic improvement. Seventy-one unselected patients consented to complete reevaluation at a mean interval of 6.1 months postoperatively. Vein bypass patency in this group was 66 percent. Eighty-two percent of these 71 patients had improved performance on electrocardiographic stress testing. There were no significant differences between hemodynamic status on pre- and postoperative studies regardless of the status of vein bypass patency. Repeat coronary angiography revealed a 30 percent incidence of new total occlusions of the intrinsic coronary circulation. Segmental wall motion on ventriculography was improved in 12 percent, unchanged in 50 percent and decreased in 38 percent of the segments analyzed. Localized electrocardiographic changes compatible with myocardial damage developed in the immediate postoperative period in 45 of these patients (63 percent); in 38 of the 45, these changes corresponded to new angiographic abnormalities. Physiologic mechanisms underlying symptomatic improvement were sought by identification of an "angina-producing" myocardial segment. In most instances, alleviation of angina could be related to either: (1) a patent bypass graft into an unchanged intrinsic coronary artery with presumed increased blood flow to the distal coronary segment, or (2) occlusion of the bypass graft and the corresponding coronary artery with probable infarction of previously ischemic myocardium. Current criteria for the selection of patients undergoing coronary bypass surgery are reviewed in the light of these findings. It is concluded that relief of disabling angina is the major indication for surgery. Prevention of myocardial infarction and improvement in left ventricular function are at present less reliable objectives.

Angina Pectoris↗
PubMed1975

Factors influencing survival following postinfarction ventricular septal defects.

Postinfarction ventricular septal defect (VSD) carries a grave prognosis. Surgical closure appears to improve survival. Eighteen patients with postinfarction VSD are reviewed. Nine died before operation could be performed and 9 underwent closure of the VSD; 4 patients are late survivors. Factors which appear to influence survival are: (1) time of surgical intervention after appearance of VSD, (2) presence or absence of cardiogenic shock, (3) location of the infarct, and (4) operative approach to the VSD. Based on these factors, a method of management for postinfarction VSD is outlined.

Aged↗
PubMed1975

The effect of cardiopulmonary bypass perfusion pressure on myocardial gas tensions in the presence of coronary stenosis.

Mass spectrometry was utilized to determine myocardial gas tensions in dogs subjected to cardiopulmonary bypass. Myocardial ischemia occurred in animals with normal coronary arteries when cardiopulmonary bypass perfusion pressure fell 40 to 60 mm Hg below the mean aortic pressure measured prior to bypass. Myocardial ischemia did not occur, or could be eliminated when present, if cardiopulmonary bypass perfusion pressure was maintained near prebypass mean aortic pressure. In animals with constricted circumflex coronary arteries, the adverse effect of low perfusion pressure on myocardial metabolism during cardiopulmonary bypass was found to be more severe in areas of myocardium supplied by the stenotic coronary artery. It is concluded that maintenance of cardiopulmonary bypass perfusion pressure near the level of preoperative mean aortic pressure will help prevent myocardial ischemia during operation; particularly in patients with coronary artery disease.

Animals↗
PubMed1975

Changes in intramyocardial ST segment voltage and gas tensions with regional myocardial ischemia in the dog.

This study was designed to evaluate the sensitivity of changes in myocardial carbon dioxide and oxygen tensions as indicators of regional myocardial ischemia and also to determine to what extent these changes can be related to changes in intramyocardial ST segment voltage. Changes in ST segment voltage recorded in unipolar epicardial electrodes proved to be a less-sensitive indicator of underlying myocardial ischemia than were changes in ST segment voltage recorded in unipolar intramyocardial electrodes. In 9 dogs, regional ischemia was produced by placing a variable constrictor on the left circumflex coronary artery; circumflex flow was monitored. Myocardial carbon dioxide and oxygen tensions were measured using a mass spectrometer. Unipolar electrograms were recorded using a multicontact plunge electrode. With progressive degrees of proximal stenosis, ranging from a critical stenosis, which is associated with a decrease in mean flow of less than 15%, to a severe stenosis associated with and 80% decrease, ST voltage increased 21 mv and carbon dioxide tension increased 84 mm Hg, but oxygen tension decreased only 7 mm Hg. The study suggests that increases in intramyocardial ST segment voltage, an index of myocardial ischemia, are associated with parallel increases in myocardial carbon dioxide tension, each providing a more sensitive quantitative correlate of regional myocardial ischemia than do decreases in oxygen tension. The local accumulation of carbon dioxide may be an important pathophysiological mechanism in myocardial ischemia.

Animals↗