Martin Brandfonbrener

Asynchronous Ventricular Pacing: A Rare Cause of Ventricular Tachycardia

Asynchronous cardiac pacing may induce ventricuiar tachycardia and fibrillation, particularly in patients with ischemic heart disease and possibly other types of myocardial abnormalities. All patients with implanted asynchronous pacemakers, and those whose demand pacemakers operate in asynchronous mode for any reason, are to he considered at risk from this complication. In patients with serious myocardial abnormalities consistent demand pacing should be assured, even if it requires early pacemaker replacement. Anti‐arrhythmic agents may prove useful for temporary suppression of pacemaker‐induced arrhythmias. (PACE, Vol. 5, July‐August, 1982)

Coronary pressure-blood flow relations: The effect of norepinephrine☆

Abstract Coronary pressure-blood flow relations were studied in anesthetized dogs by changing blood flow in the left main coronary artery and measuring coronary pressure before, during and after intracoronary norepinephrine infusion. Norepinephrine produced an increase in coronary vascular resistance in 10 of 28 experiments, usually in experimental preparations with a low initial coronary resistance. This increase in resistance occurred at different blood flow rates and was therefore not dependent on the rate of blood flow. Prior to norepinephrine infusion, coronary pressure-blood flow curves were curvilinear, convex to the pressure axis, showing a decrease in resistance with increasing blood flow except in those preparations with a low resistance in the control period. In these, resistance did not fall as flow increased from the low to the mid-flow range, but did fall as blood flow increased further.

The effect of lanatoside C on coronary vascular resistance

Abstract The effect of lanatoside C was studied in a preparation in which the flow of blood in the left main coronary artery could be accurately measured and varied. Lanatoside C produced an increase in left main coronary artery resistance at all rates of blood flow. The diluent of the drug did not affect coronary resistance. The increase in resistance persisted for the duration of the experiment. Some evidence is presented for a greater increase in resistance with larger doses.

The effect of digitalization on quinidine toxicity

Abstract The effect of quinidine on digitalized but not digitalis-intoxicated dogs was studied. One group was digitalized with a full-digitalizing dose of Cedilanid-D prior to an infusion of quinidine gluconate. Another group was given quinidine without prior digitalization. The mean blood pressure, heart rate, QRS duration, and serum potassium levels after Cedilanid-D but prior to quinidine infusion were not significantly different for the two groups. Six digitalized dogs and two undigitalized animals died before lengthening of the QRS duration to twice control values. This was not a statistically significant difference. The time of death, and thus the amount of quinidine infused, the serum potassium, and quinidine levels at death were not statistically different in the two groups. It was concluded that prior digitalization with a rapid-acting digitalis preparation has no significant effect on quinidine toxicity.