Search

Using a randomized crossover design, 1-g intravenous doses of cephalothin and cefoxitin, a cephalosporinase-resistant cephamycin, were infused into 12 normal adult males over periods of 120, 30, and 3 min, the last with and without prior intravenous infusions of probenecid (1 g). Mean peak serum concentrations of antibiotic activity after cephalothin infusions were 23, 56, 103, and 102 mug/ml, respectively, and after cefoxitin infusions they were 27, 74, 115, and 125 mug/ml, respectively. Probenecid treatment prolonged the terminal serum half-life of cephalothin-like activity from 0.52 to 1.0 h, and of cefoxitin from 0.68 to 1.4 h. In contrast to cephalothin, which was found to be metabolized about 25% to the less active desacetyl form, cefoxitin was metabolized less than 2% to the virtually inactive descarbamyl form, as judged from urinary recoveries. Neither antibiotic displayed detectable organ toxicity. Of 300 recent clinical isolates of gram-negative bacilli other than Pseudomonas spp., 83% were susceptible to cephalothin but 95% were susceptible to cefoxitin. Organisms resistant to cephalothin but susceptible to cefoxitin included strains of Escherichia coli, Proteus vulgaris, Klebsiella spp., Serratia marcescens, Enterobacter spp., and Bacteroides spp.

Myocardial blood flow was measured by the 133Xe clearance technique in 21 patients 6 to 31 months after saphenous vein grafting for coronary arterial disease. Preoperative measurements were made in 16. All patients had improved symptomatically, and 20 had returned to work. Thirty of 39 grafts were entered and selective injections of 133Xe performed. Flow in the left coronary artery (LCA) was unchanged postoperatively in 9, increased in 5, and decreased in 1 (preoperative mean = 54 ml/100 g/min, SD +/- 16; postoperative mean = 65 ml/100 g/min, SD +/- 20). Flow in the right coronary artery (RCA) was unchanged postoperatively in 3, decreased in 9, and increased in 2 (preoperative mean = 46 ml/100 g/min, SD +/- 18; postoperative mean = 33 ml/100 g/min, SD +/- 12). Nine of 14 grafts to the left anterior descending coronary artery showed flow rates significantly greater than those in the corresponding LCA. Two of the 3 circumflex grafts showed flow rates significantly lower than those in the LCA. Four of 8 right grafts showed significantly higher flow rates than those in the corresponding RCA. These findings correlated well with the angiographic appearances. We conclude that saphenous vein grafting increases total myocardial blood flow. The data suggest that the coronary arteries and the grafts are supplying different regions of the myocardium, and that the graft regions were previously underperfused. There would appear to be little mixing of blood between artery and graft regions.

Continuous electrocardiographic (ECG) records were made over 24 hours in 130 ambulant outpatients complaining of syncope, dizzy turns, or palpitation. In all these patients resting ECGs had failed to show significant dysrhythmias. Exercise testing was performed on 64 patients and also failed to reveal any dysrhythmias. Analysis of the tape recordings, however, showed appreciable dysrhythmias in 74% of the group. In most cases the dysrhythmias were complex mixtures of rapid supraventricular and ventricular rhythms. bouts of ventricular tachycardia were seen in seven patients, all of whom were women. Episodic complete heart block was seen in only two patients, but prolonged ventricular gaps (greater than 1-5 s), not associated with ectopic beats, were found in 26. No episodes of ventricular fibrillation were recorded. We conclude that many patients with vague symptoms suggestive of transient cerebral ischaemia or irregular heart action have significant and often dangerous dysrhythmias which can be diagnosed only by long-term recording of the ECG under fully ambulant conditions.