Left coronary artery-left ventricle fistula with right coronary artery spasm.

A 72-year-old woman was admitted to our hospital for evaluation of chest pain. Coronary angiography showed a left coronary artery-left ventricle fistula. An acetylcholine provocation test induced vasoconstriction of the right but not the left coronary artery. Her chest pain was not relieved by combined therapy with isosorbide dinitrate, diltiazem and nicorandil. Because of the coronary spasm, beta-blockers could not be used. However, her chest pain was relieved after the administration of a minor tranquilizer. Thus, the patient's chest pain was unlikely to be associated with either the fistula or the coronary spasm.

Ventricular tachycardia with narrow QRS duration, a right bundle branch block pattern, and right axis deviation abolished by catheter manipulation.

A 25-year-old women underwent electrophysiologic evaluation for sustained normal QRS complex tachycardia with a pattern of right bundle branch block and right axis deviation. Ventricular tachycardia was diagnosed by demonstrating fusion beats, atrioventricular dissociation, and bundle of His potential activation, which began before the onset of each QRS complex. A single ventricular extrastimulus was capable of easily provoking the tachycardia. There was an inverse relationship between the coupling interval of the first extrastimulus and the interval of the first tachycardia beat, suggesting reentry as the mechanism. The tachycardia was unexpectedly abolished during catheter manipulation in the left ventricle and has never recurred during 1 year of follow-up evaluation. The tachycardia was thought to be an unusual form of interfascicular tachycardia or microreentrant fascicular tachycardia.

Splitting of high right atrial potentials in atrial flutter with rapid pacing.

Rapid pacing from the high right atrium was performed in 7 patients with atrial flutter in whom potentials with multicomponent high-frequency deflections were recorded at the high right atrium to examine the origin of these potentials during transient entrainment in atrial flutter. In all of the patients with relatively slow rapid pacing, the potentials were captured orthodromically through the atrial flutter reentry circuit with a long conduction time. With more rapid pacing, the potentials were split into 2 associated components: P1 and P2. P1 was captured antidromically with a short conduction time whereas P2 was captured persistently in an orthodromic direction through the reentry circuit with a progressively long conduction time. In 3 of the 7 patients, atrial flutter was converted into another atrial flutter by rapid pacing. During this other atrial flutter, the potentials at the high right atrium were split from the beginning to form double potentials: D1 and D2. During rapid pacing, D1 and D2 were fused, and D1 was captured antidromically whereas D2 was captured orthodromically through the reentry circuit. In sinus rhythm, the potentials at the high right atrium formed fractionated potentials. These findings suggest that 1) fractionated potentials may represent 2 atrial regions with different conductivity properties, 2) fractionated potentials may be able to change into double potentials, and 3) double potentials may be attributable to their conductivity properties rather than refractoriness.

Radiofrequency catheter ablation for ventricular tachycardia with a right bundle branch block pattern and left axis deviation.

Ventricular tachycardia (VT) with right bundle branch block QRS morphology and left axis deviation originating in the inferolateral apical segment of the left ventricle was found in a 24-year-old man without overt structural heart disease. Intracardiac recordings during VT showed atrioventricular dissociation with the earliest activation at an apical inferolateral site in the left ventricle, where Purkinje fiber potentials were recorded fusing in the ventricular electrogram. Ventricular pacing was performed at this site, and yielded a QRS morphology identical to the VT. Radiofrequency current was applied and resulted in the complete elimination of VT.

Patterns of interruption of atrial flutter induced by rapid atrial pacing.

We evaluated the patterns of interruption of atrial flutter (AFl) induced by rapid atrial pacing in 10 patients using standard electrophysiologic techniques. We observed 3 patterns of interruption of AFl: 1) interruption resulting from block of an orthodromic wavefront within the reentry loop in 5 patients; 2) interruption when pacing impulses no longer captured all of the recording sites in the atrium during rapid atrial pacing in 2 patients, and 3) interruption with 1 echo wave after the cessation of pacing in 3 patients. These findings suggest that there are patterns of interruption of AFl other than that resulting from a simple block of an orthodromic wavefront within the reentry loop.

Study on the genesis of the double potential recorded in the high right atrium in atrial flutter and its role in the reentry circuit of atrial flutter.

To investigate the genesis of the double potential (DP), which is two separate waves, and its role in the reentry circuit of atrial flutter (AF), we performed overdrive pacing (ODP) from the high right atrium (HRA) in six cases of spontaneous AF in which the DP was recorded in the HRA. In four of the six cases, when the DP was arbitrarily designated D1 and D2, D1 and D2 showed progressive fusion during ODP. In addition, the D1 return cycle, immediately after the termination of ODP, corresponded to the AF cycle, and the D2 return cycle corresponded to the pacing cycle. This may indicate that the DP is caused by the collision of two directional waves. Furthermore, it is suggested that the HRA plays an important role in preventing a possible shortcutting of reentry waves and in stabilizing the reentry circuit of AF.