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Biomedical subjects

J J Rozanski

Publications and source records attributed to J J Rozanski.

50 records · Page 3Linked to original sources
PubMed1979

Mode of operation induced by rapid external chest wall stimulation in patients with normally functioning QRS-inhibited (VVI) pacemakers.

The effects of rapid external chest wall stimulation were evaluated in 10 patients with normally-operating unipolar, lithium-powered, QRS-inhibited pacemakers functioning in their control VVI (QRS-inhibited) mode. Stimuli delivered at slow rates resulted in the expected pacemaker inhibition. On the other hand, during rapid (greater than 900/min) external chest wall stimulation, 8 pacemakers reverted to a VOO mode, 1 to a VVI mode and 1 to either a VVI or VOO mode. No pacemaker was totally inhibited by rapid chest wall stimulation. In accordance with the manufacturer's specifications, the rate to which the implanted pacemakers reverted during the VOO modes produced by the fast external stimuli were the same as those of the VOO modes induced by proper application of an external magnet. Although rapid external chest wall stimulation proved to be a safe procedure, more studies are necessary to determine its usefulness in the follow-up of patients with implanted QRS-inhibited (VVI) pacemakers. At present, conclusions cannot be drawn regarding whether these pacemakers will revert to a mode of operation similar to that induced by rapid external chest wall stimulation when subjected to extrinsic sources of strong electromagnetic interference.

Cardiac Pacing, Artificial↗
PubMed1977

Alternans of the ST segment in Prinzmetal's angina.

Alternans of the elevated ST segment (STEA) was found in 8 of 21 patients (38%) with Prinzmetal's variant angina. In addition to STEA, all eight patients had varying cardiac arrhythmias: multiple premature ventricular depolarizations in eight, ventricular tachycardia in five, and ventricular fibrillation in three. There was no consistent temporal relationship between the occurrence of STEA and the cardiac arrhythmias. Alternans occurred during periods when no arrhythmias were present. All eight patients underwent coronary angiography. Spontaneous coronary artery spasm was documented angiographically in three patients including two who had minimal or no coronary atherosclerotic disease. Six patients had severe, fixed, occlusive coronary artery disease. Possible mechanisms for STEA include: 1) failure of regions of myocardium to depolarize on alternate beats due to variation in conduction and refractoriness between ischemic and nonischemic zones of myocardium, and 2) electrical alternans of the transmembrane action potential during phase 2 and 3 (repolarization) caused by changes in the rate and extent of electrolyte transfer across cell membranes during ischemia. It is postulated that STEA is an electrocardiographic sign in the surface ECG of a dysequilibrium of refractory periods during ischemia and reflects an unstable electrical state of the myocardium.

Adult↗
PubMed1976

Cardiac motion in total electrical alternans.

Gross pendular motion of the heart at half the heart rate was observed during cardiac catheterization and pericardiotomy in a patient with massive pericardial effusion and electrical alternans in the electrocardiogram. These observations support the hypothesis that total electrical alternans in pericardial effusion is a result of alternate change in cardiac position.

Adult↗
PubMed1976

Situs inversus, subaortic and subpulmonic stenosis, ventricular septal defect, and single coronary artery.

The unusual occurrence of situs inversus totalis, ventricular septal defect, hypertrophic subaortic and subpulmonic stenosis, and single coronary artery in a 38-year-old man is presented. The clinical course was remarkably mild, as documented by data from 23 years of study including four cardiac catheterizations. At age 35 years, however, syncope, chest pain, and marked elevation of right ventricular pressure prompted complete surgical repair of the left and right ventricular outflow tract obstructions and closure of the septal defect. Three years after surgery the patient continues to lead an active life without symptoms. The unusually mild course can be attributed to the natural banding effects of the subpulmonic stenosis which prevented irreversible pulmonary hypertension.

Adolescent↗