STUDIES OF THE CIRCULATION IN THE PRESENCE OF ABNORMAL CARDIAC RHYTHMS. OBSERVATIONS RELATING TO (PART I) RHYTHMS ASSOCIATED WITH RAPID VEN-TRICULAR RATE AND TO (PART II) RHYTHMS ASSOCIATED WITH SLOW VENTRICULAR RATE 11

Abstract

Measurements were made of cardiac output, cardiac size, arm to tongue circulation time, venous blood pressure, vital capacity, heart rate, and arterial blood pressure in patients exhibiting irregularities of the heart most frequently encountered. Electrocardiograms were taken to record the prevailing rhythm. In the case of 7 patients, the cardiac output in all except one was less during auricular fibrillation than after the reversion to normal sinus rhythm, whether the patient was or was not under the influence of digitalis at the time reversion to normal sinus rhythm occurred. In certain ones, the heart dilated during the irregularity. In those instances in which the arm to tongue cir. time was measured, it was prolonged during auricular fibrillation. The ven. pres. was elevated in those instances in which it was measured and restoration of normal sinus rhythm witnessed a fall to normal levels. In auricular flutter with rapid ventricular rate there is marked decrease in cardiac output per min. (c. o. p. m.) and very marked decrease per beat, with prolongation of cir. time and dilatation of the heart. With restoration of normal sinus rhythm changes in all these functions in the reverse direction toward a normal level occur. In 3 patients exhibiting paroxysmal tachycardia of supra-ventricular origin, this rhythm was associated with decrease in c. o. p. m. and per beat and prolongation of the c. o. time. Rise in ven. pres. did not occur. In ventricular paroxysmal tachycardia, the c. o. was decreased, the cir. time prolonged and the heart became dilated during this rhythm. With complete heart block the c. o. p. m. was decreased in 3 and normal in one patient, and the output per beat was increased or only slightly decreased. The B.M.R. was decreased in 3 subjects. The total c.o.p.m. was decreased in the presence of 2:1 heart block, as a consequence of which the cir. time was prolonged. The output per beat, due to the slow cardiac rate, was within normal limits. Coupled rhythm due to auricular premature contractions in the presence of idio-ventricular rhythm was associated with decrease in c. o. p. m., but with marked increase in the output per beat. In heart rhythms associated with rapid ventricular rate, the work of the heart per beat was not commensurate with its size while in those rhythms associated with slow ventricular rate the work per beat was within normal limits.