Biomedical subjects
Publications and source records attributed to U Althaus.
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In a comparative study the effect of the new calcium antagonist Ro 11-1781 on experimental infarct size and left ventricular function in the pig has been investigated. The calcium antagonist was administered 30 min prior to ligation of the left anterior descending coronary artery and twice daily on the following 4 days. For morphometric assessment of infarct size the ventricular myocardium was cut into slices and stained with nitro-benztoluene. There was a significant reduction in infarct size of about 25% in the calcium antagonist-treated group in comparison with the control group. After coronary occlusion left ventricular function is equally depressed in both groups, as is myocardial lactate extraction, which becomes negative.
A study was designed to examine ventricular arrhythmias in the acute phase of experimental myocardial infarction in the pig and to evaluate possible antiarrhythmogenic influence of the beta-adrenergic blocking drug pindolol (Visken) and the calcium antagonist Ro 11-1781. Ventricular fibrillation (VF) occurred in 17 of 18 animals, in 4 almost immediately after coronary occlusion and in 12 with a delay of about 17 min. VF was almost always induced by episodes of ventricular tachycardia (VT) which were started by single ventricular premature beats (VPBs). VPBs occurred in 3 phases, whereas VT and VF coincided only with phase 1 and phase 3. The prematurity index QR/QT of single VPBs decreased significantly with time after coronary occlusion. The beta-adrenergic blocking drug pindolol and the calcium antagonist Ro 11-1781 did not prevent VT or VF.
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A short period of myocardial ischemia induced by temporary ligation of 2 min duration prior to occlusion of the left anterior descending branch of the left coronary artery (LAD) in the pig does not have a beneficial effect on epicardial ST-segment alterations or on the incidence of ventricular fibrillation. One-stage ligation therefore seems to be the procedure of choice in occluding the porcine LAD. In 14 of 24 animals an isolated alternans of the ST-T segment was observed during the first few minutes of occlusion. Reperfusion after 60 min caused temporary increase of the ST-segment alterations, in contrast to the findings in the dog, where revascularization causes prompt return of the ST-segment to the pre-occlusion level. In addition, ectopic rhythms were frequently observed after removal of ligation.
The initiation and termination of ventricular tachycardia by means of programmed orthorhythmic endocardial stimulation has been studied in pigs with subacute experimental myocardial infarction. Successful stimulation implied limited variation of the number, interval, prematurity and intensity of electrical impulses.
In a comparative study the effect of pindolol (Visken, Sandoz) on experimental infarct size and left ventricular function in the pig has been investigated. Pindolol was given 30 min prior to the ligation of the left anterior descending coronary artery and on the following 5 days twice daily in a dosage of 0.05 mg/kg body weight. For morphometric assessment of infarct size the ventricular myocardium was cut into slices and stained with nitro-benztoluene. There is a significant reduction of infarct size (by one third) in the pindolol-treated group as compared to the controls. In addition, deterioration of left ventricular function is less marked in the pindolol-treated group.
The effects of myocardial reperfusion have been examined following a 1 h coronary occlusion and compared to a permanent coronary ligation in pigs. Haemodynamic investigations were carried out throughout the surgical intervention and repeated after 7 days. Cellular injury was estimated by serial serum enzyme determinations (creatin phosphokinase, alpha-hydroxybutyric dehydrogenase, aspartate aminotransferase, lactic dehydrogenase) during the first 5 postoperative days; infarct size was assessed morphometrically by a histochemical staining procedure 1 week after the temporary or permanent coronary occlusion. A linear correlation was found between the logarithmically plotted peak serum activity of AST, HBDH, CPK and the morphometrically determined infarct size. Based upon enzyme and morphometrical studies no significant difference could be detected between the two experimental groups. In the animals subjected to transient coronary occlusion, however, the development of a ventricular aneurysm had been prevented to early and sustained reperfusion. Early re-establishment of coronary circulation appears to accelerate the proliferation of a more resistant granulation tissue into the infarcted area. Cardiac performance was not improved by myocardial reperfusion.
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Up to October 1975 a total of 206 mitral commissurotomies were performed in Berne. 170 patients underwent closed commissurotomy (CMC). In the period from 1973, 36 patients underwent open commissurotomy (OMC). To compare results and operative risk as between OMC and CMC, the last 36 consecutive patients of the CMC group were selected for critical evaluation. Though not coinciding chronologically the 2 groups turned out to be essentially comparable with regard to preoperative clinical and hemodynamic findings. In neither group was there a hospital death. Frequency and severity of postoperative complications did not prove to be greater following OMC. Cerebral embolism was observed in 3 cases after CMC, whereas this complication occurred only once following OMC. On the basis of clinical, radiological and electrocardiographic data, OMC must be considered superior to CMC. The incidence of significant residual stenosis and the risk of causing mitral regurgitation appear to be lower. Without involving a higher operative risk, the open approach to mitral commissurotomy offers the following main advantages: safe removal of intraatrial thrombi, precise and complete incision of the fused commissures under direct vision, avoidance of leaflet tears, separation of fused chordae tendineae and incision of papillary muscles in order to remove subvalvular stenosis, debridement of calcium from leaflets, and repair of concomitant mitral regurgitation by valvuloplasty.
In a comparative study in pigs the extent of myocardial infarction has been estimated following a temporary three hour coronary occlusion and following a permanent coronary ligation. For evaluation of the cellular injury the infarct size has been determined by a histochemical staining procedure and correlated with serum enzyme studies (creatine phosphokinase, alpha-hydroxybutyric dehydrogenase) in the surviving animal. No significant difference could be detected between the two experimental groups and the extent of cellular damage was similar. A strict linear correlation was found between the serum enzyme activity plotted logarithmically and the morphological infarct size. Likewise the incidence of ventricular fibrillation depended on the extent of cellular injury. Myocardial revascularization does not appear to benefit a pig heart subjected to an acute coronary occlusion lasting three hours or more. Revascularization may even be harmful by creating a haemorrhagic infarct, as found in all the animals submitted to a transient coronary occlusion.
A total of 4063 surgical interventions for arterial occlusions of the lower limbs have been reviewed in a retrospective study. As compared to patients without specific diagnosis of preexisting coronary heart disease, the incidence of postoperative myocardial infarction is 10 times greater in the presence of clinical and electrocardiographic evidence of previous infarction; for patients suffering from typical angina pectoris the risk is 5 times higher and for patients with suspected preoperative infarction the incidence of postoperative infarction is 3 times that in surgical patients without such a history. The mortality rate from myocardial infarction occurring postoperatively in patients with no previous history of coronary heart disease is 26% as compared to 100% for patients who had sustained preoperative infarction. The rate of recurrence is significantly greater when the time interval between previous myocardial infarction and operation is less than three months. Comparison between elective and emergency cases shows that in the group undergoing emergency surgery the incidence of post-operative infarction is twice that under elective surgery, whereas mortality from myocardial infarction is 3 times higher following acute interventions. The problem of critical establishment of surgical indication, the need for accurate prior investigations and the requirement of adequate preoperative treatment are discussed.
36 children operated upon with the diagnosis coarctation of the aorta have been controlled in a follow-up examination. We payed special attention to the surgical technique and brought the results in connection with the method of operation. One group had the stenosis corrected by resection and end-to-end-anastomosis, the second group with plastic operation, either by a longitudinal incision, resection of a diaphragm and transverse closure, or by improving the dilatation using a dacron patch. The results in both groups are satisfactory. Actually we prefer to carry out the resection with end-to-end anastomosis. Plastic correction remains reserved for selected cases. We believe that the high mortality rate in infants can be reduced by operation in hypothermy and by removing the stenosis as completely as possible.
In a comparative study the degree of myocardial damage has been estimated following one hour coronary occlusion and following a permanent coronary ligation in pigs. With regard to infarct size, no significant difference could be detected between the two experimental groups; the extent of cellular injury as determined by a histochemical staining procedure and by serial serum enzyme studies in the surviving animal is of equivalent degree. Nevertheless, the development of a ventricular aneurysm can be prevented by early reperfusion. Reestablishment of coronary circulation appears to accelerate the proliferation of a more resistant granulation tissue into the infarcted myocardial area. Our hemodynamic findings suggest that the effect of reperfusion is unfavourable in the immediate phase; later on, however, coronary reperfusion appears to be beneficial to cardiac function.
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