Electrophysiologic drug testing in prophylaxis of sporadic paroxysmal atrial fibrillation: technique, application, and efficacy in severely symptomatic preexcitation patients.

Electrophysiologic drug testing was performed in nine patients with severely symptomatic sporadic (2 to 13 [mean 4.2] attacks/24 months) paroxysmal atrial fibrillation (PAF). All patients had control inductions of sustained (greater than 30 seconds) AF by high right atrial stimulation, and attempted inductions following serial administration of drugs. Drugs tested were intravenous procainamide (1.0 to 1.5 gm) (five patients), intravenous propranolol (0.1 mg/kg) (three patients), oral quinidine (1.6 to 2.4 gm/day) six patients), oral disopyramide (1.2 to 1.6 gm/day) (four patients), and oral aprindine (100 to 250 mg/day) (four patients). In all patients, one or more drugs prevented induction of sustained AF: procainamide (one patient), quinidine (five patients), disopyramide (four patients), and aprindine (four patients). All patients were treated with drugs which prevented induction of sustained AF and followed for 8 to 40 (mean 24) months. Seven patients tolerated their drugs: six had no AF and one had several short nonsustained attacks. Two patients did not tolerate their drugs: one had paroxysmal palpitation (on decreased aprindine dosage), and one had AF (while off of aprindine). In conclusion, electrophysiologic drug testing is feasible in patients with sporadic PAF. Inability to induce sustained AF following drug administration suggests successful prophylaxis of spontaneous PAF with the same drug.

Chronic nonparoxysmal junctional tachycardia.

We describe an adult with chronic (three years' duration) acquired nonparoxysmal junctional tachycardia, a previously undescribed rhythm. Ambulatory monitoring revealed junctional rates ranging from 75 to 110 beats/min. Electrophysiologic studies demonstrated intact atrioventricular and ventriculoatrial conduction with a normal H-V interval (43 msec) and narrow QRS. Underlying sinus node function appeared to be normal (recovery time of 900 msec). Junctional rate increased with administration of atropine and isoproterenol, suggesting that the junctional pacemaker was located in the proximal His bundle. Electrocardiographic and electrophysiologic observations suggested that this case of chronic nonparoxysmal junctional tachycardia was benign, not necessitating therapy.

Paroxysmal atrial fibrillation in the Wolff-Parkinson-White syndrome.

Eighty-eight patients with preexcitation were studied to determine how 30 patients with documented spontaneous paroxysmal atrial fibrillation differed from 58 patients without this arrhythmia. Inducible reentrant tachycardia was present in 23 (77 percent) of the 30 patients with, versus 28 (48 percent) of the 58 patients without, atrial fibrillation (p less than 0.025). Heart disease was present in 13 (43 percent) of the 30 patients with, versus 15 (26 percent) of the 58 patients without, atrial fibrillation (not significant). Inducible reentrant tachycardia or heart disease, or both, were significant). Inducible reentrant tachycardia or heart disease, or both, were present in 29 (97 percent) of the 30 patients with, versus 34 (59 percent) of the 58 patients without, atrial fibrillation (p less than 0.0005). Of 51 patients with inducible reentrant tachycardia, 23 patients with atrial fibrillation did not differ from 28 patients without this arrhythmia with respect to clinical features and atrial, sinus nodal, or anomalous pathway properties, or cycle length of induced reentrant tachycardia. Spontaneous degeneration of induced reentrant tachycardia to atrial fibrillation was observed in 6 (26 percent) of 23 patients with, versus none of 28 patients without, atrial fibrillation (p less than 0.025). In summary, patients with preexcitation and documented spontaneous paroxysmal atrial fibrillation almost always have inducible reentrant tachycardia or heart disease, or both. It is likely that in many patients with inducible reentrant tachycardia, spontaneously occurring reentrant tachycardia relates to induction of atrial fibrillation. However, it is unclear why some patients with inducible reentrant tachycardia have atrial fibrillation and others do not. In many patients with organic heart disease, atrial fibrillation could relate to hemodynamic changes.

Visualization of atrial myocardium with Tl-201: case report.

A case of right atrial visualization on Tl-201 imaging in a patient with marked right atrial enlargement secondary to atrial septal defect is described. The misinterpretation of Tl-201 an gated cardiac studies on initial inspection, due to this unusual finding, and the importance of obtaining special lateral and oblique view for correct identification of cardiac chambers are discussed.

Serial electrophysiologic testing of multiple drugs in patients with atrioventricular nodal reentrant paroxysmal tachycardia.

Serial electrophysiologic testing of multiple drugs was performed in 21 patients with recurrent atrioventricular (AV) nodal reentrant paroxysmal supraventricular tachycardia (PSVT). All patients had reproducible sustained PSVT induced before drug administration. Serial daily PSVT induction was attempted after administration of i.v. ouabain (0.01 mg/kg) (16 patients), i.v. propranolol (0.1 mg/kg (17 patients), i.v. ouabain + propranolol (same dosages) (12 patients), i.v. procainamide (600-1000 mg) (17 patients) and oral quinidine (1600-2400 mg/day) (nine patients). In two of 21 patients (10%), no tested drug prevented induction of sustained PSVT. In 19 of 21 patients (90%), one or more drugs prevented induction of sustained PSVT: ouabain--seven patients, propranolol--seven patients, ouabain + propranolol--seven patients, procainamide--11 patients, quinidine--seven patients. The site of action of ouabain and/or propranolol was either the antegrade limb or the retrograde limb (RL) of the circus movement. The site of action of procainamide or quinidine was always the RL. These 19 patients were treated with oral drugs, based on results of serial testing. Eighteen patients were successfully followed for 6-50 months. In 13 of these 18 patients PSVT did not recur. Two patients (11%) had > 95% reduction in frequency of PSVT recurrences, and three (17%) did not respond to chosen oral drugs. Serial electrophysiologic testing of multiple drugs is feasible in patients with AV nodal reentrant paroxysmal tachycardia. Drug responses are variable. In most but not all patients, serial electrophysiologic testing defines effective prophylactic drug therapy. This method of defining prophylactic drug therapy appears most suitable for patients with poorly tolerated tachycardias that occur only sporadically.

Cycle length in atrioventricular nodal reentrant paroxysmal tachycardia with observations on the Lown-Ganong-Levine syndrome.

Sixty-five patients with dual pathway atrioventricular (A-V) nodal reentrant paroxysmal tachycardia were studied. Of these 65 patients, 11 (17 percent) had a short P-R interval (0.12 second or less) and 3 (5 percent) had a short A-H interval (53 ms or less) during sinus rhythm, suggesting the Lown-Ganong-Levine syndrome. Frequency distribution analyses of P-R and A-H intervals in the 65 patients demonstrated continuous unimodal functions, suggesting a continuum of A-V nodal properties. Regression analyses of P-R and A-H (fast pathway) intervals versus cycle length of paroxysmal tachycardia revealed an r value of 0.11 and 0.10, respectively (not significant). The cycle length of paroxysmal tachycardia did not differ between the 11 patients with a short P-R interval (370 +/- 20 ms) and the 54 patients without a short P-R interval (382 +/- 11 ms). Regression analysis of the slow pathway A-H interval versus cycle length of paroxysmal tachycardia revealed an r value of 0.68 (p less than 0.001). The cycle length of dual pathway A-V nodal reentrant paroxysmal tachycardia is a function of the slow pathway A-H interval and not the P-R or A-H interval during sinus rhythm. Identification of short P-R intervals in patients with A-V nodal reentrant paroxysmal tachycardia has little significance.