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Biomedical subjects

A S Geha

Publications and source records attributed to A S Geha.

At least 73 records · Page 4Linked to original sources
PubMed1982

Factors affecting performance and thromboembolism after porcine xenograft cardiac valve replacement.

Long-term durability and the need for anticoagulation in conjunction with the use of porcine valves remain questionable. We analyzed valve dysfunction and thromboembolism in 325 adult (older than 20 years) and 31 pediatric survivors who received 407 porcine xenograft valves from June, 1974, to September, 1980 (46% of all valve replacements). Valves at risk in the adults were 216 aortic, 138 mitral, and 22 tricuspid; in children, 14 aortic, eight mitral, seven pulmonary, and two tricuspid. Mean follow-up was 38 (9 to 85) months. Twenty-seven valved conduits also were followed up for 9 to 85 (mean 52) months. Two late deaths in children resulted from dysfunction and another from endocarditis. One late death in an adult was caused by embolism. The other 36 deaths in the entire group were not valve related. Dysfunction requiring reoperation at 12 to 37 months occurred in eight of 325 adults (six mitral, one aortic, and one tricuspid). Dysfunction was due to recurrent endocarditis in six and to primary tissue failure in two (both older than 35 years of age); all survived reoperation. However, in children, severe dysfunction due to primary tissue failure occurred in seven (23%) cardiac valves, necessitating replacement at 21 to 48 months, and three of 27 conduits had to be replaced at 39 to 70 months. Thromboembolism occurred in six adults with mitral xenografts but none with aortic or tricuspid valve. Four of the patients with thromboemboli (one of whom died) were among 16 who had atrial fibrillation and no warfarin, but aspirin and persantine (11.7%/patient-year) and two were among 14 with sinus rhythm on no medication. No thromboembolism occurred in patients with mitral xenografts who were in sinus rhythm and receiving antiplatelet agents or in those with atrial fibrillation receiving warfarin. This experience indicates a high incidence of relatively early failure of porcine xenograft cardiac valves in children and young adults but excellent medium and long-term performance in older adults, in whom severe dysfunction occurred mainly with recurrent endocarditis. Thromboembolism occurred primarily in patients with mitral replacement especially with atrial fibrillation and no anticoagulants.

Adult↗
PubMed1982

The role of mediastinoscopy and mediastinotomy in lung cancer.

Mediastinoscopy and mediastinotomy have a major role in patients with bronchogenic carcinoma. In some instances, they lead to a histologic diagnosis of a tumor of unknown cell type seen by chest roentgenogram, when other diagnostic methods have failed to do so. By far the most important role of these procedures is to stage the mediastinum for better selection of patients for surgery. Thoracotomy has a low morbidity and mortality; nevertheless, it is a formidable operation. If thoracotomy is used indiscriminately in patients with bronchogenic carcinoma who are referred for surgical treatment, many of these patients "lose, just through the operation, one or two of the best months they have left to live." In the five categories of patients described, mediastinoscopy and mediastinotomy are the most effective and economic methods for predicting who will benefit from thoracotomy and resection.

Biopsy↗
PubMed1981

Catheter-induced pulmonary artery perforation. Mechanisms, management, and modifications.

Six cases of pulmonary artery perforation associated with the use of Swan-Ganz catheters are reviewed. Risk factors included pulmonary hypertension, anticoagulation, and hypothermia. The mechanisms leading to perforation were clarified by the use of postmortem studies employing isolated whole lung preparations. These studies revealed that perforation results from (1) tip perforation of vasculature, (2) eccentric balloon configuration propelling the balloon through the vessel wall, and (3) balloon inflation disrupting the pulmonary artery (mean intraballoon pressure 250 mm Hg). Early clinical symptoms include hemoptysis of bright red blood and/or hypotension. Immediate evaluation may necessitate examination with a fiberoptic bronchoscope and "wedge" angiogram. If massive hemoptysis occurs, isolation of the unaffected lung by endobronchial intubation is mandatory. Pneumonectomy or lobectomy may be required. Revised guidelines for catheter insertion and pulmonary capillary wedge pressure (PCWP) measurements are presented. Finally, consideration is given to redesigning the pulmonary artery flow-guided catheter, particularly for use in patients undergoing cardiac operations with systemic anticoagulation. Modifications should be directed at (1) softer catheter tip with temperature-insensitive body, (2) low-pressure balloon, and (3) balloon pressure relief valve.

Aged↗
PubMed1981

Use of silicone rubber as a pericardial substitute to facilitate reoperation in cardiac surgery.

Reoperations following cardiac procedures have an increased risk because of the danger of damaging the heart, great vessels, or grafts because of adhesions to the sternum and anterior chest wall. We report our experience with the use of silicone rubber as a pericardial substitute in 102 patients--58 children undergoing palliative and corrective operations and 44 adults undergoing porcine valve insertion or coronary revascularization. The pericardial substitute was used only in cases in which reoperation was considered likely. There were no mediastinal infections. One adult had signs of cardiac constriction which improved markedly on administration of anti-inflammatory agents. Seven patients required reoperation for bleeding. Two patients who underwent Fontan procedures developed pericardial effusions necessitating a pericardial window. Reoperation was undertaken 1 to 12 months postoperatively in seven patients, all of whom were children. The silicon rubber greatly facilitated opening of the chest bone but did not affect the formation of adhesions within the pericardium. Postmortem examinations have been obtained in two cases 5 and 9 months postoperatively, and showed a thin layer of dense fibrous tissue adjacent to the silicone rubber. We conclude that silicone rubber may be used as a pericardial substitute and that it facilitates reoperation following cardiac operations. Particular caution should be used in patients undergoing Fontan procedures, as there appears to be a tendency for pericardial effusions and tamponade to develop.

Adult↗
PubMed1981

Dysfunction and thromboembolism associated with cardiac valve xenografts in adults.

Cardiac valve xenografts often fail relatively early in children. We analyzed the incidence of valve dysfunction and thromboembolism in 253 consecutive adult survivors who received 294 porcine xenograft valves (150 aortic, 125 mitral and 19 tricuspid) from June 1974 to December 1979 (41% of all adult valve replacements). Mean follow-up was 25.6 months (range 9-75 months). Valve dysfunction occurred in four of 294 xenografts (three in mitral position and one in tricuspid position), all four caused by recurrent endocarditis; these four patients survived reoperation and are doing well. Thromboembolism occurred in six of 294 xenografts, none in aortic or tricuspid positions of rhythm or anticoagulation. Four of the six mitral xenografts associated with thromboembolism were in the 16 patients who had atrial fibrillation and received aspirin and dipyridamole but no warfarin (12% per patient-year), and two were in the 14 patients who were in sinus rhythm and were not taking medication, one of whom had recurrent Candida endocarditis. No thromboembolism occurred in mitral xenografts with sinus rhythm and antiplatelet agents. Thromboembolism did not occur in patients who were in atrial fibrillation and receiving warfarin anticoagulation. Late death (30 of 253) was unrelated to valve dysfunction, and only one death resulted from thromboembolism. This study showed excellent xenograft performance for as long as 75 months. Valve dysfunction occurred only with recurrent endocarditis, and thromboembolism occurred after mitral replacement, especially in patients who were in atrial fibrillation and were not receiving anticoagulants.

Adult↗
PubMed1981

Randomized comparison of the modified wire-guided and standard intra-aortic balloon catheters.

We have designed a modified intra-aortic balloon (IAB) catheter to facilitate balloon insertion and minimize the complications of vascular dissection, perforation, and thrombosis. The modified balloon catheter is fabricated of a new polyurethane, Avcomat-100; it has a central lumen which allows for pressure monitoring, contrast injection, and introduction of a guide-wire under fluoroscopic control. In a randomized study, we compared the modified balloon with the standard Avco balloon catheter. Eighteen patients were randomized, 10 to receive a standard balloon catheter (control group) and eight to receive a modified balloon catheter. In two of the 10 patients assigned to the control group, introduction of the standard catheter failed but a central-lumen balloon was successfully introduced using the guide wire. A guide wire was needed for introduction of the modified balloon in three of the eight patients assigned to the central-lumen catheter group. The Avcomat-100 catheter material was less thrombogenic, with a lower rate of femoral thrombosis--20% in the control group and 0% in the central-lumen group. Scanning electron miroscopy also showed a reduced area of catheter surface covered with fibrin and clot. This study demonstrates the safety, decreased thrombogenicity, and increased facility of insertion of this new balloon catheter.

Adult↗
PubMed1980

Acute renal failure in cardiovascular and other surgical patients.

The acute onset of oliguria and azotemia in the postoperative setting may be caused by prerenal or postrenal causes or intrinsic renal damage. The first step in arriving at a diagnosis is to review the history in order to elicit the extrarenal factors. Certain simple laboratory tests are of tremendous value in differentiating these conditions. The development of acute renal failure with renal parenchymal damage usually occurs in the setting of hypotension, sepsis, dehydration, and with exposure to nephrotoxins. Most patients will be excreting scant amounts of isotonic urine containing more than 20 to 30 mEq per liter of sodium. Their urine:plasma creatinine ratio is less than or equal to 20:1 and their urinary sediment reveals many epithelial cells and casts. The condition is usually reversible and the treatment is expectant. However, it is still associated with a high mortality, although the survival of patients with acute renal failure may be substantially higher than previously reported. Early dialysis and nutritional support may play an important role in the improved survival. Patients with nonoliguric acute renal failure have urine outputs that may exceed 2 liters per day. Despite this output they demonstrate a stepwise increase in serum urea and creatinine. Urine sodium and osmolality are not very helpful. Many such patients do have low (less than 20 mEq per liter) urine sodium concentration and excrete isotonic urine.

Acute Kidney Injury↗
PubMed1980

Bypass surgery for left main coronary artery disease. Reduced perioperative myocardial infarction with preoperative intra-aortic balloon counterpulsation.

From July 1975 to December 1977, 91 consecutive patients with left main coronary artery disease defined by cardiac catheterisation as greater than or equal to 50 per cent luminal narrowing underwent coronary bypass surgery. Prospective examination of the preoperative and postoperative clinical course of these patients was performed to determine the incidence of perioperative myocardial infarction. Intra-aortic balloon counterpulsation was instituted preoperatively in 35 patients, and these patients were classed as group A. Fifty-six patients did not receive the intra-aortic balloon pump and were classed as group B. Of 26 demographic, clinical, haemodynamic, and operative descriptors, only two were found to be significantly different between the two groups: the severity and the pattern of angina. Group A had a higher percentage of patients with class IV angina (80% vs 45%) and a greater proportion with unstable angina (37% vs 7%). Despite these differences group A patients had only a 3 per cent incidence of perioperative myocardial infraction while group B had a 23 per cent perioperative infarction rate. It is suggested that perioperative intra-aortic balloon counterpulsation can reduce the risk of perioperative myocardial infraction in patients with left main coronary artery stenosis.

Assisted Circulation↗