Intermittent parasystole with concealed bigeminy

A case is reported of ventricular extrasystolic rhythm showing the features of concealed ventricular bigeminy, and intermittent ventricular parasystolic rhythm, both arising from the same ectopic ventricular focus.     

Analysis of human atrial fibrillatory waves using monophasic action potential technique.

In 29 patients with atrial fibrillation, using the monophasic action potential technique, the fibrillatory waves were recorded and analyzed by statistical methods. Concerning the characteristics of the fibrillatory waves there are no differences between patients with rheumatic heart disease and with coronary heart disease. The patients with paroxysmal forms and those without heart failure and with normal heart size, have similar statistical data with regard to their fibrillatory waves. From the data presented, it could be possible to predict the efficacy of conversion to sinus rhythm and also the sinus rhythm stability after conversion.     

Sinoventricular conduction in atrial standstill.

Sinoventricular rhythm implies preserved sinus node function with conduction of impulses to the A-V junction without generalized atrial excitation. Impulse propagation in such cases is presumably via specialized internodal tracts. In this present case, synchronized but localized activation from an area of the right atrium preceded each QRS, without generalized atrial depolarization. These recordings are offered as further evidence for the clinical occurrence of sinoventricular rhythm in humans.     

Intermittent parasystole with concealed extrasystolic bigeminy during myocardial infarction.

A 72-year-old man demonstrated persistent intermittent ventricular parasystole for 6 days during an acute inferior wall myocardial infarction. Entrance block failure occurred at a critical interval of 1.24 sec. after parasystolic beats with resetting of the parasystolic cycle length. The first ectopic beat in each parasystolic series showed coupling to its second preceding conducted beat, and successive cycle lengths in each series usually showed gradual shortening. Concealed extrasystolic bigeminy was also demonstrated between parasystolic series with the number of intervening conducted beats conforming to the formula 2n + 2. After interpolated parasystolic beats, this formula became 2n + 3.     

Organized left atrial mural thrombus demonstrated by coronary angiography

Small coronary artery fistulas terminating at the site of adherent, organized mural thrombi in the left atrial appendage were observed during selective coronary angiography in patients with mitral stenosis. The angiographic features of this abnormality can be distinguished from those of cardiac tumors, vascular malformations, and coronary artery fistulas that are not associated with organized thrombus. This coronary angiographic abnormality may indicate the presence of left atrial thrombus that is not revealed by echocardiography and is not manifest clinically by systemic emboli. The size of the collection of radiographic contrast material in the left atrium is not proportional to the size of the thrombus.     

Prolonged atrial conduction

We describe a patient, in whom electrophysiologic study revealed a "negative" P-A interval in the His bundle electrogram, a prolonged intraatrial conduction time and a prolonged spike to the P wave interval during atrial pacing. The abnormalities were due to extensive sinuatrial disease.     

Right atrium monophasic action potentials during atrial flutter and fibrillation in man.

Monophasic action potentials recorded in two patients with atrial flutter and one patient with atrial fibrillation showed a nonuniform depolarization of the right atrial wall. In each of the two patients with atrial flutter, there was a site where two separate action potential deflections were recorded for each flutter wave. It was supposed that this was the site of re-entry for a cycling wavelet subsidiary to the main flutter wave. In the patient with atrial fibrillation, three types of electric atrial activity were found: regular activity at 180 per minute similar to that found in flutter, small irregular activity at a rate of 400 per minute, and a mixed type of the former two. The significance of these findings for the mechanism of atrial flutter and fibrillation is discussed.     

The supernormal phase of intraventricular conduction: normalization of intraventricular conduction of premature atrial beats

This report presents the analysis of a case in which numerous atrial extrasystoles, associated with normal intraventricular conduction, occurred during sinus rhythm conducted with right bundle branch block. The wide overlap of coupling intervals of normally conducted extrasystoles and other extrasystoles with right bundle branch block seemed prima facie to negate the possibility of supernormality. Rearrangement of these intervals, however, to allow for the timing of right bundle branch depolarization with respect to the ensuing QRS complex, resulted in a clear cut separation of all normalized complexes from those with right bundle branch block. All normalized extrasystoles were localized in a zone very early in the cycle. This finding, in the presence of atrial extrasystoles with normal P-R intervals, strongly supports the mechanism of supernormality in this case. Alternate explanations do not appear to be tenable.     

Effects of dobutamine on atrioventricular conduction.

Dobutamine, a new beta-stimulating catecholamine, has been investigated in terms of its effect upon atrioventricular conduction. Bundle of His recordings were obtained on six patients in basal conditions and with right atrial pacing at rates of 100, 120, and 140 per minute. Recordings were repeated following intravenous administration of Dobutamine in doses of 5, 10, and 15 mug per kilogram per minute. Dose-response curves were thus obtained for A-H and H-V intervals. Heart rate increased only moderately with progressive concentrations of the drug. Very significant facilitation of A-H conduction was demonstrated with doses of 10 and 15 mug per kilogram per minute, with no effect upon H-V times. Dobutamine may be a clinically useful inotropic agent in conditions associated with A-V conduction disturbances.     

Sinus node echoes and concealed concealed conduction: additional sinus node phenomena confirmed in man by direct sinus node electrography

Direct sinus node electrography has been previously used to assess several aspects of sinus node physiology: sinus node pauses, overdrive suppression, sinoatrial entrance block. This report presents data in which sinus node electrograms confirm two additional physiologic phenomena in man: concealed conduction in the sinoatrial junction and sinus node reentry. These findings verify the presence of previously suspected phenomena by careful deductive analysis of electrocardiographic and electrographic tracings.     

Complex atrial arrhythmias studied by suction electrode technique.

Two elderly patients with coronary heart disease, chronic pulmonary disease, and complex atrial arrhythmias are presented. The suction electrode technique for right atrium monophasic action potential recording was used. This recording allows better analysis of the atrial arrhythmias and estimates the stability of focal activity.