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Biomedical subjects

R M Rossen

Publications and source records attributed to R M Rossen.

14 recordsLinked to original sources
PubMed1978

Electrophysiologic findings in patients with idiopathic hypertrophic subaortic stenosis.

Thirteen patients with catheterization-proved idiopathic hypertrophic subaortic stenosis underwent intracardiac electrophysiologic study. There was a large incidence of arrhythmias and a strikingly large incidence of conduction system abnormalities among these patients. The P-A and A-H intervals were normal in all patients. Atrial pacing resulted in Mobitz type 1 block proximal to the His bundle at an abnormal rate (less than 140/min) in 2 of 12 patients (17 percent). H-V intervals were prolonged (greater than 50 msec) in 10 of 12 patients (83 percent) and were greater than 60 msec in 7 patients (58 percent). The atrial effective refractory period was prolonged in 3 of 12 patients and was markedly prolonged in 1 of them. Effective refractory period of the atrioventricular (A-V) node, determined in five patients, was prolonged in three. Dual responses of the A-V node to atrial extrastimuli were found in seven patients. Dual A-V nodal repsonses were evoked with propranolol in three patients and persisted in the other four patients with dual responses despite propranolol administration.

Adult↗
PubMed1976

The effect of cycle length on cardiac refractory periods in the denervated human heart.

We have previously demonstrated that the transplanted human heart is functionally denervated. With the use of the extra stimulus technique during His bundle electrocardiography, refractory periods of the arterioventricular (A-V) conduction system were determined at several heart rates after pacing-induced changes in cycle length in eight patients who had previously undergone cardiac transplantation. Shortening of the cycle length was accompanied by a decrease in both the effective and functional refractory periods of the atrium. No consistent change in A-V nodal effective refractory period or functional refractory period could be demonstrated. Because A-V conduction was limited at shorter cycle lengths by the functional refractory periods of the atrium and A-V node, bundle branch refractory periods could be determined in three patients only at the longest cycle length studied. In four of the eight patients, atrial arrhythmias were produced at short cycle lengths with the introduction of early atrial extra stimuli. This may be due to a lack of vagal innervation of the atrium. These results contribute to our understanding of atrial arrhythmias.

Adult↗
PubMed1976

Circulatory response to vasodilator therapy in congestive cardiomyopathy.

Vasodilator therapy has been shown to have beneficial effects in heart failure. In order to evaluate the haemodynamic actions of vasodilator administration in primary congestive cardiomyopathy, sodium nitroprusside was infused intravenously at a rate of 15 to 100 mug/min to 12 patients. Mean arterial pressure fell 15 per cent from 86+/-3-0 to 72+/-2-4 mmHg (11-40 +/- -4 to 9-6 +/- 0-3 kPa), and there was a small but significant decrease in mean heart rate from 96 +/- 4-8 to 90 +/- 4-4 beats/min. These changes were accompanied by a significant decrease in mean pulmonary artery pressure from 40 +/- 2-2 to 26 +/- 2-8 mmHg (5-3 +/- 0-3 kPa to 3-5 +/- 0-4 kPa), mean pulmonary capillary wedge pressure from 25 +/ -2-2 to 16 +/- 2-1 mmHg (3-3 +/- 0-3 to 2-1 +/- 0-3 kPa), and left ventricular end-diastolic pressure from 27 +/- 1-8 to 17 +/- 1-5 mmHg (3-6 +/- 0-3 to 2-3 +/- 0-2 kPa). Cardiac index increased by an average of 48 per cent from 2-1 to 3-1 l/min per m2, and left ventricular stroke work index increased from 18-4 +/- 1-6 to 21-3 +/- 1-9 g m/m2. These results show that pronounced left ventricular dysfunction in patients with congestive cardiomyopathy is improved during vasodilator therapy.

Adult↗
PubMed1976

Bacterial endocarditis after cardiac catheterization.

Bacterial endocarditis is a rare complication of cardiac catheterization. We present the history of a patient who developed fatal, acute bacterial endocarditis following diagnostic cardiac catheterization. The implications regarding antibiotic prophylaxis and catheterization technique are discussed.

Cardiac Catheterization↗
PubMed1975

A-V conduction disturbances in Reiter's syndrome.

High grade atrioventricular (A-V) block is a rarely described complication of Reiter's syndrome. This 65 year old man had recurrent episodes of arthritis, conjunctivitis and urethritis beginning at age 16. A prolonged P-R interval was first noted at age 32. The conduction distrubance progressed to intermittent episodes of high grade and complete heart block by age 65. His bundle electrograms located the site of block above the level of the bundle of His. Atrial pacing to rates of 150/min produced 5:1 A-V block, whereas exercise and atropine administration resulted in 1:1 A-V conduction. In view of these results, artificial pacemaker therapy is not indicated. The association of conduction disorders and Reiter's syndrome is reviewed.

Aged↗
PubMed1975

Sinus node function in the denervated human heart. Effect of digitalis.

Evaluation of sinus node function was performed in 5 patients with an intact cardiac autonomic nervous system (group I), and in 8 patients with a transplantated, denervated heart (group 2). After baseline data were recorded, the electrophysiological studies were repeated in all group I patients and in 6 of the 8 group 2 patients, 45 to 60 minutes after the administration of digoxin 1.25 mg intravenously. Baseline cycle length, sinus node recovery time, and sinoatrial conduction time were significantly shorter in the transplanted heart than in those with intact autonomic innervation, but correction of the sinus node recovery time and sinoatrial conduction time for heart rate abolished these differences. Digoxin produced a small increase in cycle length, sinus node recovery time, and sinoatrial conduction time which did not reach statistical significance in this small study group of patients with innervated hearts. In the denervated, transplanted patients, no change in cycle length occurred after digoxin in any patient. The sinus node recovery time was unaffected by glycoside administration in 3 of 6 patients, while the sinoatrial conduction time was unchanged in 4 of 6. In one group 2 patient, digoxin produced first degree sinoatrial node exit block, and in a second patient, 2:1 sinoatrial nodal exit block developed. The mechanisms responsible for these effects in the denervated heart are not clear.

Adult↗
PubMed1975

Effect of digoxin on atioventricular conduction. Studies in patients with and without cardiac autonomic innervation.

The effect of digoxin on atrioventricular (a-v) conduction was compared in five patients with an intact cardiac autonomic nervous system (Group I) and seven patients who had undergone cardiac transplantation (Group II), in whom we have previously shown the transplanted heart to be completely denervated. Small decreases in the atrial effective refractory period (ERP) (from 262 plus or minus 12 to 254 plus or minus 11 msec) and atrial functional refractory period (FRP) (from 304 plus or minus 12 msec) were observed in Group I patients after digoxin, but these changes were not significant. However, significant increases in the A-V nodal ERP (from 315 plus or minus 18 msec to 351 plus or minus 17 msec, P less than 0.05), and A-V nodal FRP (from 426 plus or minus 42 to 460 plus or minus 46 msec, P less than 0.01) were produced by digoxin and were unrelated to changes in cycle length. In Group II patients with denervated hearts, changes in atrial ERP (from 246 plus or minus 4 to 243 plus or minus 6 during spontaneous sinus rhythm; from 204 plus or minus 10 to 216 plus or minus 8 msec during atrial pacing) and atrial FRP (from 311 plus or minus 12 to 316 plus or minus 11 msec during spontaneous sinus rhythm; from 254 plus or minus 12 to 260 plus or minus 10 msec during atrial pacing) were not significant. However, in contrast to the Group I patients, the digoxin-induced changes in A-V nodal ERP (from 280 plus or minus 22 to 297 plus or minus 18 msec during atrial pacing) and FRP (from 368 plus or minus 18 to 377 plus or minus 18 msec during spontaneous sinus rhythm; from 334 plus or minus 13 to 346 plus or minus 16 msec during atrial pacing) were also statistically insignificant. Our results demonstrate that the electrophysiologic effects of digoxin on atrioventricular conduction in man are most marked in the atrioventricular node and are dependent on cardiac innervation

Adult↗
PubMed1975

Treadmill arrhythmias in patients with idiopathic hypertrophic subaortic stenosis.

Treadmill tests were performed in 19 patients with previously documented idiopathic hypertrophic subaortic stenosis (IHSS). Arrhythmias occurred in 79 percent (15) of the patients, and new arrhythmias not previously documented occurred in over 50 percent (10) of the patients. Paroxysmal supraventricular tachycardia (PSVT), ventricular premature beats (VPBs) (two or more per minute) or atrial premature beats (APBs) (three or more per minute) occurred in 10 of 19 patients. There was no association between treadmill arrhythmias and clinical symptoms, hemodynamic data, or electrocardiographic features. Propranolol administration resulted in failure of exercise to induce PSVT in one patient and had no effect on PSVT in two others, nor any effect on maximum frequency of APBs or VPBs. Treadmill testing is more productive than retrospective analysis of ECGs for characterizing arrhythmias in IHSS.

Adult↗