Biomedical subjects
Publications and source records attributed to G Merin.
Coarctation of the aorta is amenable to surgical correction or balloon dilatation. In a 6-month-old girl with multiple intracardiac anomalies, re-coarctation, which followed surgical repair at 16 days was successfully dilated.
Three hundred forty-eight consecutive patients were evaluated during 1985 and 1986 for the development of complete atrioventricular (AV) block after coronary artery bypass grafting. Cold (4 degrees) asanguineous potassium cardioplegia with temperature monitoring was used uniformly. AV block developed in 56 instances (16%). In 32 patients (group 1) the block was transient (less than 6 hours) and in 24 it was persistent (group 2). Left main coronary artery stenosis in conjunction with total obstruction of a dominant right coronary artery occurred more commonly in patients manifesting AV block (18 of 56, 32%) than in those without it (35 of 292, 12%) (p less than 0.05). Complete occlusion of a dominant right coronary artery was observed with equal frequency in patients with and without AV block. The presence of an ungraftable right coronary artery, however, was significantly more frequent in the AV block group: 16 of 37 (47%) vs 6 of 194 (3%) (p less than 0.01). Endarterectomy of the right coronary artery was performed in 8 of 24 patients (33%) with persistent AV block versus none in the patients with transient AV block (n = 32) or normal sinus rhythm postoperatively (n = 292) (p less than 0.0001). Persistent AV block (greater than 6 hours) was associated with myocardial infarction in 6 patients (25%) (p less than 0.05) and with low cardiac output in 18 patients (75%) (p less than 0.0001). In conclusion, AV block after myocardial revascularization was frequently associated with the presence of multivessel coronary disease and an ungraftable dominant right coronary artery. Persistent (greater than 6 hours) AV block was correlated with both perioperative myocardial infarction and low cardiac output.
We have developed a technique for autotransfusion of shed mediastinal blood collected in the cardiotomy reservoir. Results in the first 50 consecutive patients in whom the system was employed were studied prospectively (group A) and were compared with those of the last 50 consecutive patients operated on before application of the new method (group B). The mean preoperative hematocrit (about 42%) and the total postoperative bleeding (about 11) were similar in both groups. Only 24 patients (48%) in group A required homologous blood transfusion, versus 43 (86%) in group B (p = 0.0001). This resulted in a 57% saving of blood units in group A (mean, 1.16 +/- 1.49 units per patient versus 2.72 +/- 1.99 in group B, p less than 0.0001). Foreign blood transfusion was thus avoided in 21 of the last 25 patients (84%) of group A. 7 days after operation, the mean hematocrit in group A was 30.9 +/- 4.3, compared with 33.0 +/- 3.8 in group B (p less than 0.001). Hemolytic jaundice occurred in 7 group B patients (14%) but in none in group A (p less than 0.01). A trend towards reduction in other complications was also demonstrated. We conclude that the use of foreign blood transfusions in those undergoing open heart surgery can be reduced significantly by this method, thus avoiding immediate transfusion reactions and minimizing the risks of late complications.
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Positive end-expiratory pressure (PEEP) is used liberally whenever a ventilated patient shows signs of increased pulmonary venous shunting. Clinicians using PEEP to improve blood oxygenation may face the cardiovascular side effects which limit utilization of the desired respiratory effects of PEEP. We measured the pressure flow characteristics of the cardiovascular system and the coronary arterial system as a function of PEEP, using closed-chest surgically instrumented dogs, in order to assess its effects on myocardial blood flow with respect to the left ventricular energy demands. The aortic left ventricular blood pressure as well as the aortic blood flow decreased with increasing PEEP values. The coronary blood flow decreased by 5% for PEEP values of 4 cm H2O, and by 25% for 14 cm H2O of PEEP. PEEP values under 10 cm H2O reduced the left ventricular end-diastolic pressure (LVEDP), while higher PEEP values caused an increase in LVEDP. The relation between the alterations of coronary and aortic blood flows changed with PEEP values. Low PEEP values (less than 10 cm H2O) had a tendency for higher relative reduction of aortic blood flow, whereas higher PEEP values (higher than 10 cm H2O) reduced the coronary blood flow more than the reduction occurring in the aortic blood flow. Our results suggest that low PEEP values may have beneficial effects on the relation between aortic blood flow and coronary blood flow, therefore low PEEP application may minimize hypoxic myocardial alterations. Further studies that will measure left ventricular workload or another metabolic index for estimating myocardial perfusion relative to its metabolic demand are essential before clinical conclusions can be drawn from our results.
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High-dose fentanyl anesthesia is widely used in cardiac surgery. Its immediate side-effects are well known. However, its late adverse effect manifested by extreme truncal rigidity, decreased chest wall compliance, hypoventilation, respiratory acidosis and hemodynamic instability is not sufficiently appreciated. Of 380 patients who underwent aortocoronary artery bypass under high-dose (100 micrograms/kg) fentanyl anesthesia, 29 (7.6%) developed the sudden onset of extreme thoracic and abdominal rigidity, leading to respiratory depression 2 to 6 h postoperative, after an apparently normal recovery from the anesthesia. In 15 patients, a high plasma level of fentanyl (5.2 to 7.8 ng/ml) correlated with the clinical events. Administration of naloxone or a muscle relaxant rapidly reversed this late complication of fentanyl, thought to be due to re-entry of fentanyl into plasma from deposits in adipose tissue, muscle and the GI tract, leading to a secondary peak in plasma fentanyl. It is more likely to be encountered when hypothermia, rewarming, and acidosis occur in the postoperative period. Awareness of this life-threatening complication is critical in patients undergoing surgery with fentanyl anesthesia.
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Three hundred sixteen consecutive patients undergoing coronary artery bypass were studied for postoperative electrocardiographic conduction disturbances. Fifty-five of these 316 patients had postoperative bundle branch block (Group 1). This group had a higher incidence of left main coronary stenosis, together with previous inferior myocardial infarction, than patients without postoperative conduction disturbances (Group 2). Perioperative myocardial infarction, low cardiac output, and death were significantly more common in Group 1 than in Group 2: 7.3% versus 1.9% for perioperative myocardial infarction, 16.4% versus 2.7% for low cardiac output, and 5.5% versus 0.8% for death. Analysis of the type of conduction disturbances indicates that the presence of a new complete left bundle branch block postoperatively in a patient undergoing coronary artery bypass is a sign of intraoperative myocardial damage. This damage is potentially lethal, especially in a patient with left main coronary stenosis and previous inferior myocardial infarction.
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The value of oxygenated, aqueous, cold cardioplegic solutions is being evaluated at several centers. The theoretical advantages of such a solution are counterbalanced in part by the complexity and expense of the preparation and delivery systems that have been used. A simple method is described that effectively achieves satisfactory levels of oxygenation of the cardioplegic solution within its original vinyl container.
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Splenic abscess is an uncommon disease that has a high mortality rate if not treated surgically. With the aid of new diagnostic tools, such as ultrasonography, scanning and computerized axial tomography, it is possible to diagnose the entity antemortem. Even though it often has a nontypical clinical course, it may overlap other systemic diseases. We describe an unusual case of splenic abscess with rare complications, the operation and the outcome.
Early repair of acute rupture of the ventricular septum after myocardial infarction is now the procedure of choice accepted by most centers. Rupture of the right ventricular free wall is rare and usually is accompanied by tamponade. The finding of coincidental right ventricular free wall rupture and acute ventricular septal defect following myocardial infarction and their successful repair are discussed in the following report.
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