Effect of nitroglycerin on vulnerability to ventricular fibrillation during myocardial ischemia and reperfusion.

The effect of nitroglycerin on vulnerability to ventricular fibrillation was examined in 44 chloralose-anesthetized dogs. In 19 animals ventricular fibrillation threshold was measured before and during a 10 minute period of occlusion of the left anterior descending coronary artery followed by abrupt release of occlusion. Fibrillation threshold was determined using the single stimulus and train of stimuli methods.

Cerium tissue/organ distribution and alterations in open field and exploratory behavior following acute exposure of the mouse to cerium (citrate).

Cerium chloride (1:3 complex with sodium citrate) was administered to male Swiss mice (6 to 8 weeks old) either intragastrically or subcutaneously at the 7 day LD5 or LD25 level. Open field behavior (ambulations, rearings) was quantified and tissue/organ Ce levels determined at 4 hr., 1, 3 or 7 days post administration.

Semiautomated data reduction of ventricular ectopic activity: methodology and clinical application.

A semiautomated ventricular premature beat (VPB) detector was developed which detects VPBs based upon a logical combination of prematurity, amplitude, and width. This system utilizes technicians to define sensitivity and criteria of VPB detection and to monitor the system's performance using a unique feedback system. Technician-assisted semiautomated scanning was found superior both to the system using preselected criteria and sensitivity of the detectors, and to traditional Holter scanning for the detection of single and repetitive VPBs.

Precordial mechanical stimulation for exposing electrical instability in the ischemic heart.

Sequenital mechanical pulsing of the chest wall with three stimuli failed to induce arrhythmias in normal dogs. After coronary arterial occlusion, this technique evoked in 11 of 12 animals repetitive ventricular tachycardia in 2. These responses corresponded closely to those elicited by electrical testing.

Roles of psychologic stress and autonomic nervous system changes in provocation of ventricular premature complexes.

Neural and psychologic factors have been implicated as risk factors for ventricular arrhythmias and sudden death in man. However, the relation between these factors and arrhythmia has hitherto not been systematically explored. We examined the effect of psychologic stress testing in 19 patients with advanced grades of ventricular arrhythmias.

Energy requirement for defibrillation of a markedly overweight patient.

Recommendations have been made recently that the energy output of present-day defibrillators be increased above the 400 wsec limit. These recommendations are based largely on experimental studies in animals. We report a case of a man weighing 190.

Protective effect of the vagotonic action of morphine sulphate on ventricular vulnerability.

Administration of morphine sulphate to 16 anaesthetised dogs resulted in significant reduction in ventricular vulnerability to fibrillation. The repetitive extrasystole threshold was used as an index of vulnerability to ventricular fibrillation. In 14 dogs, atropine or vagotomy abolished this response.

Central neurochemical factors related to serotonin metabolism and cardiac ventricular vulnerability for repetitive electrical activity.

Sympathetic neural activity modifies cardiac excitability and lowers the threshold of the vulnerable period for ventricular fibrillation. Sympathetic neural traffic to the heart can be diminished by administering serotonin precursors that localize in the central nervous system. In this study anesthetized dogs were injected with either of the serotonin precursors L-tryptophan or 5-hydroxy-L-tryptophan in conjunction with the monoamine oxidase inhibitor pheneizine and the selective peripheral L-amino acid decarboxylase inhibitor carbidopa.

The effects of psychological stress and vagal stimulation with morphine on vulnerability to ventricular fibrillation (VF) in the conscious dog.

Ventricular vulnerability to fibrillation was assessed in 12 conscious dogs in aversive and nonaversive environments using the repetitive extrasystole (RE) threshold method. In the average environment, RE threshold was 45 per cent lower than in the nonaversive setting and heart rate and blood pressure were significantly elevated. This decrease in RE threshold occurred within 10 minutes of exposing the animals to stress.

Effects of clonidine on vulnerability to fibrillation in the normal and ischemic canine ventricle.

Clonidine infusion (10 microgram/kg, i.v.) elicited a 30% increase in repetitive extrasystole (RE) threshold in 6 chloralose-anesthetized dogs.