Exercise Echocardiography in Patients with Chronic Aortic Regurgitation: A Serial Echocardiographic and Clinical Follow-up Study

In patients with chronic aortic regurgitation, irreversible left ventricular dysfunction, which is associated poor longterm prognosis, often develops before onset of severe symtoms. To determine whether evidence of left ventricular dysfunction could be detected before it appeared at rest, 48 patients with chronic aortic regurgition were studied using exercise echocardiography, and 25 patients were followed-up for 16.1 months in average by serial echocardiographical and clinical examination to evaluate the prognostic value of exercise-echocardiographic data. Among 41 patients with normal resting ejection fraction, left ventricular ejection fraction increased more than 5% with exercise(big up tri, DeltaEF> or =5%) in 14 patients (Group I), while in 27 patients ejection fraction change with exercise was less than normal (big up tri, DeltaEF <5%) (Group II). In the remaining 7 patients with subnormal resting ejection fraction, the exercise response was also subnormal (big up tri, DeltaEF<5%)(Group III). 1) There was no significant difference in radius-thickness ratio, ejection fraction at rest, work capacity, exercise duration and NYHA functional class between group I, II and III. But left ventricular internal dimension and wall stress were greater in group II than in group I. Group III had the largest left ventricualr internal dimension and stress. 2) Among the 15 patients with left vnetricular end-systolic dimension(LVESD) greater than 55mm, only one patient belong to group I. The other 14 patients belonged to group II(7 patients) and group III(7 patients). In contrast, in 22 patients with LVESD less than 50mm, 13 patients were group I, 9 patients were group II. In 26 patients with LVESD greater than 50 mm, only one patient showed normal exercise response, but the remaining 25 patients showed subnormal response. 3) Serial echocardiographic and clinical follow-up study for average 16.1 months showed group I the best, group II better than group III, group III the poorest clinical course and prognosis. Left ventricular functional status of group II patients seemed to be intermediate stage between group I and group III. 4) Total work duration and work capacity were more reduced in NYHA functional class II and III than in class I. But, using NYHA functional classification there were no differences in left ventricular internal dimension, ejection fraction at rest, exercise change in ejection fraction(big up tri, DeltaEF), wall stress and radius-thickness ratio between class I, II and III. According to the above results the classification based on the resting ejection fraction and big up tri, DeltaE.F., seemed to be useful for identification of patients with different clinical course and prognosis, especially in asymptomatic cases. The consideration of indices obtained by exercise-echocardiography, such as, LVESD, resting ejection fraction, big up tri, DeltaE.F. and wall stress, as well as the clinical status of patient, would be a useful guideline for follow-up and determining the optimal time for surgical intervention in patients with chronic aortic regurgitation.

Antitachycardia Pacemaker PASAR 4172 for Termination of Paroxysmal Tachycardias

Reentrant tachycardias can often be terminated by discrete pacing stimuli that penetrate the reentrant circuit. Antitachycardia pacemaker PASAR 4172 (Programmable Automatic Scanning Arrhythmia Reversion, Model 4172, Telectronics) is designed to detect tachycardia automatically and subsequently to deliver programmed one or two extrastimuli to revert to sinus rhythm. We experienced two patients, one paroxysmal supraventricular tachycardia and one paroxysmal ventricular tachycardia, who had had frequent and often prolonged episodes of tachycardia that responded poorly to pharmacologic antiarrhythmic therapy. Each patient underwent a detailed preimplantation clinical electrophysiological study in order to determine the number of stimuli required for termination of tachycardia, the most satisfactory site for electrode placement, and the tachycardia termination zone. During the follow-up period of 7 to 11 months after implantation of PASAR 4172, no patient complained of an episode of sustained tachycardia although they experienced symptoms of an impending attack. We conclude that antitachycardia pacemaker PASAR 4172 is a safe, effective, and well tolerated method for the therapy of drug resistant paroxysmal supraventricular tachycardia and paroxysmal ventricular tachycardia.