Biomedical subjects
Publications and source records attributed to G Merin.
This is a report of successful management of a traumatic rupture of the thoracic aorta in pregnancy. Both mother and daughter are alive and well 24 months after the injury. The various aspects of the surgical and supportive treatment are discussed.
Severe hypertension non-responsive to medical therapy was discovered in a 27-year-old woman in the third trimester of pregnancy. Renal arteriography after delivery revealed bilateral renal artery stenosis. The right kidney was smaller than the left one. The differential renal function studies, rather than the renal vein renin measurements, identified which side was causing the hypertension. An attempt at primary repair of the right renal artery failed. Orthotopic renal autotransplantation, using saphenous vein grafts that were interposed between the renal veins and the inferior vena cava, and between the segmental renal arteries and the abdominal aorta, reduced the blood pressure to normal values.
Thirteen patients who had mitral valve surgery were studied within 3 hours after operation. The patients were divided into 2 groups: group A with initial low cardiac index (1.70 +/- 0.25), elevated left atrial pressure (16.5 +/- 6.7) and high peripheral vascular resistance (2623 +/- 789); group B with initial normal cardiac index (3.71 +/- 0.54), normal left atrial pressure (13 +/- 3.5) and normal peripheral vascular resistance (1223 +/- 303). In both groups the mean arterial pressure was elevated (98 +/- 8.8, 96 +/0 15.8). An infusion of nitroprusside to reduce the mean arterial pressure to either 80 mmHg or 10% below the initial value had different effects in each group. In group A, cardiac index (CI) increased by 23%, left atrial pressure (LAP) decreased by 20%, pulmonary artery pressure (PAP) by 35%, and peripheral vascular resistance (PRV) by 32%. In group B, CI decreased by 8%, LAP by 32%, PAP by 30% and PVR by 13%. When LAP returned to initial values after an infusion of blood with continued infusion of nitroprusside, CI increased in both groups (27%, 11%) and the PVR remained lower (40%, 29%). The study demonstrates the favorable effect on cardiac output of vasodilator therapy on patients with elevated blood pressure, impaired by left ventricular function and high LAP, after surgery on mitral valve. The optimal effect is achieved by keeping the LAP within normal limits.
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The effects of direct intracoronary injection of meglumine diatrizoate (RENOGRAFIN) on regional myocardial contractility were studied in 11 open-chested dogs. The left anterior descending or circumflex artery was cannulated selectively from the ascending aorta and the changes in myocardial contractile force and its first derivative were measured by an epicardial strain gauge sutured to the myocardium supplied by the cannulated artery. The myocardium perfused by the non-cannulated artery served as the control area. Direct intracoronary injection of meglumine diatrizoate, 1 ml, caused regional depression of myocardial function, with a significant decrease in contractile force and its first derivative in the study area; there was no change in the control area, nor were there changes in the first derivative of left ventricular pressure, heart rate or systemic blood pressure. There was no additive depressant effect after multiple injections. Local pretreatment with hydrocortisone (4 mg/kg, by slow intracoronary infusion) ameliorated the myocardial depressant effect of meglumine diatrizoate so that there was a smaller decrease in contractile force and its first derivative. The results may have clinical significance in patients undergoing coronary arteriography.
The echocardiographic features of pulmonary valvar atresia with intact ventricular septum are described. The pulmonary valve fails to open during systole: there is a large pre-systolic 'a' wave dip, but the pulmonary valve membrane then returns to its closed diastolic position where it remains for the remainder of the cardiac cycle. The echocardiogram also provides valuable information about right ventricular size, the tricuspid valve, and aorta-mitral and aorta-septal relations.
A new method is described for stabilizing dehiscence or instability of median sternotomy incisions using stainless steel retention sutures. The method has been used successfully in patients who had disruption of the sternum following open-heart surgery and resulted in no complications. It is recommended also as a preventive measure for closure of the sternum in elderly, debilitated patients with a fragile sternum and with prolonged low cardiac output after operation.
A 41-year-old man underwent an uneventful aorta-coronary bypass for unstable angina pectoris. Four hours later, a massive anterior wall myocardial infarction resulted in cardiac arrest. Conventional resuscitative means were not effective. A left ventricular assist device (LVAD) was successfully employed for 94 hours. The patient is alive and well 8 months postoperatively.
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The left anterior descending or left circumflex coronary artery was cannulated selectively in 10 dogs. Methylprednisolone, 1 mg per kilogram of body weight, was injected into the artery and the cannula was withdrawn. The animals were then subjected to hemorrhagic shock for 90 minutes. Retransfusion to prestudy blood pressure was then accomplished. The electrocardiogram, arterial blood pressure, contractile force, and first derivative of contractile force were recorded continously both from the areas that were pretreated and those that were not, the controls. Contractile force in the control area was reduced to 32 +/- 3.2% of the preshock period after 90 minutes of shock, whereas in the pretreated area it was twice as high at the same time. Ten minutes after transfusion, the contractile force of the pretreated area exceeded the preshock level, whereas the recovery of contractile force in the control area reached only 70% of the preshock level. This study shows that intracoronary infusion of methylpredisolone can afford myocardial protection in hemorrhagic shock to a significant degree.
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An experiment was designed to measure accurately the primary effect of verapamil on myocardial contractility by infusion of the drug directly into the coronary artery of open-chested anesthetized dogs. A marked myocardial depressant effect, which was dose and time dependent, was noted during verapamil infusion at the infused area only. The percent decrease in contractile force ranged from 8.8 at an infusion rate (mg/min) of 0.55 X 10(-2) to 36.8 at 5.5 X 10(-2). Similar changes were observed in the first derivative of the contractile force. No changes were observed in the left ventricular systolic or end-diastolic pressure and only a mild increase in contractile force was noted in the control (noninfused) area. The depressant effect of verapamil was sustained. Recovery time after 5 min of verapamil infusion was dose dependent, ranging from 10 to 45 min. During the recovery period, an overshoot of the contractile force was observed in dogs on the higher doses only. We concluded that verapamil in clinically relevant doses has a marked negative inotropic effect of long duration and therefore should be used with caution in patients with depressed left ventricular function. Cessation of the verapamil treatment may cause a transient increase in myocardial contractility, which might be hazardous in patients with angina pectoris who have compromised coronary blood flow.
The hemodynamic effects of dopamine were studied in 19 patients following intracardiac operation or myocardial revascularization using extracorporeal circulation. The heart rate, mean blood pressure, central venous pressure, left atrial and pulmonary artery pressures, cardiac output, and urine output were recorded before and at the end of one-hour infusions of dopamine at 5, 10, and 15 mug/kg/min. Infusion of 5 mug/kg/min of dopamine resulted in the highest gain in cardiac output and stroke work without an increase in myocardial oxygen consumption, as evidenced by lack of significant rise in heart rate. In addition, this dosage was not accompanied by an increase in pulmonary or systemic vascular resistance, nor were other untoward effects observed after administration of 5 mug/kg/min of dopamine.
A case is presented in which shock developed suddenly during implantation of a permanent pacemaker. The cause proved to be pericardial tamponade secondary to catheter perforation. Analysis of this case and the 6 similar cases reported in the literature reveals that although perforation occurs not infrequently from immediately to many months after implantation, tamponade is quite rare and is invariably closely related temporally to catheter manipulation. Tamponade has occurred with different catheter sizes and makes. It is more likely related to local myocardial factors than to faulty technique. Closed pericardiocentesis is generally unsuccessful in relieving the tamponade, and prompt open drainage through the subxiphoid approach is recommended.
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A 46-year-old male patient with atypical angina pectoris appeared to have an important elongated stenosis of the left main coronary artery on coronary arteriography, and slight irregularities in the left anterior descending, circumflex, and right coronary arteries. A saphenous vein bypass graft to the left anterior descending artery was performed, and this relieved the patient's symptoms. Postoperative coronary arteriography demonstrated a widely patent left main coronary artery and graft. The original narrowing of the left main coronary artery was probably caused by spasm and the source of the patient's anginal symptom.
The repair of ventricular septal defect (VSD) in corrected transposition of the great arteries has presented many technical problems and was associated with a high mortality. Transatrial closure of the VSD in this malformation obviates many of the hazards and offers good exposure. The operative procedure in such a case is described in detail, and its merits are discussed.
A case of diffuse supravalvular aortic stenosis including the ascending aorta, the aortic arch, and its branches is presented. The operative procedure employed for correction is presented in detail and discussed. This is the first report of the successful surgical treatment of this type of malformation.