Hans H. Scheld

Revascularization of the right coronary artery: Influence thermodilution right ventricular ejection fraction

This study was designed in order to evaluate the influence of right coronary artery (RCA) disease and its revascularization on right heart performance monitored by measuring thermodilution right ventricular ejection fraction (RVEF). Forty patients undergoing elective aortocoronary bypass surgery were divided into two groups: group 1, with RCA revascularization, n=20; and group 2, without RCA disease or revascularization, n=20. RVEF was measured using a pulmonary arterial catheter mounted with a fast-response thermistor and a bedside microprocessor ejection fraction computer. The major finding of the study was that myocardial revascularization with extracorporeal circulation was followed by a decrease in RVEF which was significantly more pronounced in group 1 (-13.1%) in comparison to group 2 (-5.0%). RVEF gradually increased after bypass, but did not reach baseline values. By the first postoperative day, RVEF had reached baseline values again in group 1 and had increased beyond baseline values in group 2. Traditionally measured hemodynamic parameters could not be correlated with the course of RVEF, except for cardiac index. The present study further suggests that right-sided events may have clinical effects on left-sided function. Inadequate protection of the right heart, especially in patients with RCA stenosis, may result in depression of right ventricular myocardial performance, which can be monitored serially by measuring RVEF.

Pediatric heart transplantation for congenital heart disease and cardiomyopathy

Orthotopic heart transplantation has become an accepted therapy for adult patients with end-stage heart disease. In newborns and infants, this procedure is still controversial because of the unknown long-term results and the lack of donor organs. Since March 1988, we have performed orthotopic heart transplantation in 11 infants and children with hypoplastic left heart syndrome (n = 6), cardiomyopathy (n = 4), or congenital endocardial fibroelastosis (n = 1). The smallest infant was 3 days old and weighed 2,650 g. Four of 15 potential donors had to be refused for various medical reasons, and 4 were transferred to our hospital for organ retrieval. Seven hearts were procured remotely. We accepted weight mismatches up to 105% between donor and recipient. There were three perioperative deaths, two in patients 5 and 17 days old with hypoplastic left heart syndrome and 1 in a 2-year-old patient with a dilated cardiomyopathy. All 3 patients had drug-resistant right heart failure. A 2-year-old girl with a dilated cardiomyopathy died 2 months after transplantation owing to severe pulmonary embolism originating from the superior vena cava. The remaining 7 patients are alive and well between 1 month and 31 months after transplantation. Angiographic follow-up has not revealed signs of graft atherosclerosis at 2 years.

Influence of cardiac output on thermal-dye extravascular lung water (EVLW) in cardiac patients

The influence of varying cardiac output (CO) on thermal-dye extravascular lung water (EVLW) was investigated in a total of 40 cardiac surgery patients before the onset of the operation. EVLW was measured by means of the double indicator dilution technique with indocyanine green as the non-diffusible inducator and a microprocessed lung water computer 15 min and 30 min after change of CO. CO was varied from -45% to +70% of the baseline value by nifedipine infusion (CO↑, n=20) or halothane application (CO↓, n=20), respectively. CO was measured from the femoral artery instream thermistor tipped lung water catheter and, simultaneously, from the pulmonary artery. In spite of a highly significant decrease (-45%) and increase (+70%) in CO no change in EVLW could be observed. CO estimation was comparable for both methods used. Regression analysis revealed no relationship between CO and EVLW as well as between EVLW and various hemodynamic parameters. We conclude that thermal-dye technique for estimation of EVLW may be accurate in spite of changing cardiac output over a wide range.

Ultrastructure of the Human Myocardium after Intermittent Ischemia Compared to Cardioplegia

A lot of reports informed about the detrimental effects of intermittent ischemia nevertheless this method is still used during coronary surgery. We investigated the myocardial protection due to cardioplegic arrest compared to intermittent ischemia in 120 patients undergoing coronary surgery. In all patients we took myocardial biopsies from the left ventricle before and after ischemia. Electron microscopic studies of all biopsies were performed and the degree of ultrastructural alteration was determined. The ischemic period in the cardioplegic group was 61 +/- 15 minutes and in the group with intermittent ischemia the total ischemic time was 45 +/- 21 minutes. After ischemia the myocardium showed most time only damage of moderate or light degree, while after intermittent ischemia the most biopsies showed severe ultrastructural damage. From our results we conclude, that intermittent ischemia is unable to protect the myocardium in a sufficient amount and should therefore no longer be used as a method of myocardial protection.

Decreasing the risk of aortic arch replacement

Eight patients underwent surgical therapy because of acute dissection of the aortic arch. In all cases surgery was performed using hypothermic circulatory arrest. Seven patients survived without neurologic defi ciency. Postoperative angiography confirmed the complete resection of the diseased part of the aorta. This method of operative treatment allows inspection of the operative field with out disturbance by blood flow and es tablishes adequate cerebral protec tion. By using presealed prostheses, application of fibrin glue, and auto- transfusion, the authors were able to limit the risk of bleeding, which is the leading cause of death in surgery of acute aortic dissection.

Coronary Endarterectomy in Patients with Diffuse Coronary Disease

Diffuse multivessel disease can limit a complete revascularization in patients undergoing coronary bypass surgery. It is considered that coro nary endarterectomy (CEA) offers a reasonable chance for this special group of patients. Among 2415 patients undergoing coronary bypass surgery, a CEA of the right and/or left coronary system had to be performed in 397 patients with diffuse multivessel disease. Completeness of the procedure was controlled intraoperatively by dye perfusion and angioscopy. One hun dred one patients gave informed con sent to be reinvestigated clinically and by angiography at an average of forty-three months after surgery. The thirty days mortality after additional CEA was slightly in creased at 3.8%. Also the periopera tive infarction rate increased at 9.3 % . The long-term analysis re vealed a late mortality of 5.5%. Cor onary angiography showed a patency rate of the endarterectomized vessels of 81.2 %; 91% of the patients being reinvestigated showed an improved or asymptomatic clinical status. Despite a slightly increased risk, CEA proved to be a feasible therapy in this strictly limited group of pa tients, in whom conventional bypass surgery offers poor chances and who otherwise would even be candidates for transplantation.

Cardiac transplantation in infants

Indications and timing of cardiac transplantation for children are more complex, because problems of rejection, graft atherosclerosis, and growth have been noted. On the basis of animal studies and of improvements in surgical techniques and neonatal cardiopulmonary bypass, we established an infant cardiac transplantation program

Blood Conservation in Cardiac Operations. Cell Separation Versus Hemofiltration

The effects of hemoconcentration performed during and after extracorporeal circulation by either centrifugation (cell separation group, n = 20) or hemofiltration (n = 20) were investigated in 40 patients undergoing elective aorta-coronary bypass grafting. Interest was focused on the quality of the blood concentrated from the blood remaining in the extracorporeal circuit and on the reaction of the patients after retransfusion of the concentrated products. Hemofiltration was easy to perform and produced whole blood quicker than the cell separation technique. Coagulation studies revealed no significant differences in heparin concentration, levels of fibrinogen and antithrombin III, or platelet counts. Various coagulation parameters tended to normalize completely and more quickly after hemofiltration than after centrifugation. None of the patients had severe bleeding postoperatively. Free hemoglobin levels were not affected by hemofiltration; elastase concentration was higher only immediately after retransfusion of the concentrated blood, with no effect on organ function. We conclude that both methods were effective means of hemoconcentration during extracorporeal circulation and in salvaging the diluted pump blood after extracorporeal circulation. Loss of plasma fraction is an important disadvantage in the centrifugation technique, which can be avoided by hemofiltration; derangement in colloid osmotic pressure and coagulation parameters was less pronounced after hemofiltration. Costs were lower, as well. Therefore, when a high volume of cardioplegic solution and two-stage cannulation are used, hemofiltration seems to be the method of choice for blood conservation during cardiac operations.

Aortenbogenersatz bei der akuten Aortendissektion

Bei der akuten Aortendissektion handelt es sich um ein katastrophales Ereignis, welches die Wandung des Aortenbogens zerstoren kann. Unbehandelt versterben etwa 50% der Patienten mit Lokalisation der Dissektion im Aszendens- und Aortenbogenbereich innerhalb von 24 Stunden (1,11,17). Einigkeit besteht derzeit in der Literatur, das Dissektionen dieser Lokalisation einer sofortigen Operation bedurfen.

Restoration of Venous Patency in Thrombosis of the Caval Veins

This paper describes the results of treatment of 15 patients with inferior vena cava thrombosis. Thrombolysis using urokinase was the method of choice (12 patients) unless there were contraindications when thrombectomy (three patients) was performed. Thrombolytic therapy produced complete clearance of the inferior vena cava in eight of the 12 patients and partial clearance in the remaining four. Thrombolysis was terminated because of minor bleeding complications in four. Thrombectomy was done in three patients in whom there were contraindications to thrombolytic therapy. We believe that thrombolysis is a feasible method of treatment and possibly the method of choice when the thrombus is older than 3 days and the patients general state is poor.