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To investigate the relationship between clot formation and thromboembolism, canine blood was withdrawn into catheter-syringe or catheter-steerable wire systems containing either contrast medium or normal saline as used in debubbling techniques. The contrast media used were iohexol, iopamidol, ioxaglate, and diatrizoate. Without the use of heparin, after a 30-minute incubation, blood clots were harvested from all catheter-syringe systems except those with diatrizoate and from all catheter-steerable wire systems. Significantly more blood clot was harvested from the catheter-steerable wire system. With use of heparinized blood, no clot was found in any system. Twelve dogs that underwent coronary angiography were divided into two groups; one received heparin (5,000 IU) and the other did not. Thromboembolism occurred in all nonheparinized dogs that underwent angiography with iohexol or iopamidol but not in any other group. The authors found that in a dog model nonionic contrast media are more thrombogenic than ionic contrast media, especially in the catheter-steerable wire system. The blood clot in the catheters is associated with thromboembolism during angiography. The authors maintain that in this setting, blood clotting and thromboembolism with nonionic agents can be eliminated with heparin.

Over an 11-year period, 28 instances of acute myocardial infarction and bilateral bundle-branch block were encountered. Twenty-two of these patients had right bundle-branch block and left axis deviation, and six had right bundle-branch block and block of the inferior radiation of the left bundle. The overall incidence of complete heart block in these 28 cases was 21%. In-hospital mortality for the whole group was 36%, whereas it was 33% for those patients who developed complete heart block. From these results it is concluded that for the patient with bilateral bundle-branch block and acute myocardial infarction the prophylactic insertion of a temporary transvenous pacemaker is not only warranted, but is probably indicated.

Subspeciation of penicillin susceptible alpha-hemolytic streptococci is not routinely performed. However, Streptococcus MG-intermedius is an extremely virulent organism in this strep subgroup and is associated with abscess formation. Our patient, who had endocarditis due to this organism, remained chronically ill despite appropriate antibiotic therapy, and had a perforated aneurysm of the sinus of Valsalva with a myocardial abscess that required extensive surgical debridement. Persistent fever in patients with S MG-intermedius endocarditis should warrant further work-up for metastatic or myocardial abscess formation.

In an 11-year period 209 cases of partial bilateral bundle-branch block were seen. These included patients with right bundle-branch block and either left superior or left inferior intraventricular block. The majority of patients had evidence of coronary artery disease or hypertension, though a significant number had no clinical evidence of heart disease. The majority of patients had follow-up ECG tracings, with an average follow-up for the whole group of about 2 years. The incidence of complete heart block was 14.4% (30 of 209). Complete heart block developed more than 10 years after the discovery of bilateral bundle-branch block in several patients. It is anticipated that with more complete and longer follow-up the incidence of complete heart block will be even higher.