In vivo validation of the origin of the esophageal electrocardiogram.

Esophageal electrocardiography is a clinical and investigational technique that is useful for determining atrial conduction intervals, analyzing atrial rhythms and mapping conduction pathways. Although the left atrial origin of the esophageal electrocardiogram has long been implied, recently that origin has been questioned. In the present study, the origin of the esophageal deflection is defined by direct right and left atrial mapping studies performed with simultaneous esophageal electrograms obtained from three positions (high, mid and low). Seven patients with normal left atrial dimensions (group I) and five patients with left atrial enlargement (group II) underwent transseptal catheterization during the course of electrophysiologic study. In group I (normal left atrial dimensions), conduction time from the high right atrium to each of the three esophageal positions corresponded to conduction times to left atrial sites ranging from 1 to 3 cm lateral to the left interatrial septum. The mid- and low esophageal conduction times were all significantly longer than conduction time to the left side of the septum (p less than 0.05). In group II (enlarged left atrium), conduction times to each of the esophageal sites corresponded to conduction times to left atrial sites lying between the mid-left atrium and a point 1 cm lateral to the left side of the septum. A significant trend toward longer conduction time to the mid-esophageal position than to the left septum was noted (p less than 0.1). In both groups, conduction times measured with the esophageal catheter were significantly longer than conduction time to the right interatrial septum (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The multicenter study of enhanced external counterpulsation (MUST-EECP): effect of EECP on exercise-induced myocardial ischemia and anginal episodes.

OBJECTIVES: The purpose of this study was to assess safety and efficacy of enhanced external counterpulsation (EECP). BACKGROUND: Case series have shown that EECP can improve exercise tolerance, symptoms and myocardial perfusion in stable angina pectoris. METHODS: A multicenter, prospective, randomized, blinded, controlled trial was conducted in seven university hospitals in 139 outpatients with angina, documented coronary artery disease (CAD) and positive exercise treadmill test. Patients were given 35 h of active counterpulsation (active CP) or inactive counterpulsation (inactive CP) over a four- to seven-week period. Outcome measures were exercise duration and time to > or =1-mm ST-segment depression, average daily anginal attack count and nitroglycerin usage. RESULTS: Exercise duration increased in both groups, but the between-group difference was not significant (p > 0.3). Time to > or =1-mm ST-segment depression increased significantly from baseline in active CP compared with inactive CP (p = 0.01). More active-CP patients saw a decrease and fewer experienced an increase in angina episodes as compared with inactive-CP patients (p < 0.05). Nitroglycerin usage decreased in active CP but did not change in the inactive-CP group. The between-group difference was not significant (p > 0.7). CONCLUSIONS: Enhanced external counterpulsation reduces angina and extends time to exercise-induced ischemia in patients with symptomatic CAD. Treatment was relatively well tolerated and free of limiting side effects in most patients.

Exercise capability and myocardial perfusion in chronic angina patients treated with enhanced external counterpulsation.

BACKGROUND: Enhanced external counterpulsation (EECP) has been shown to improve treadmill times and myocardial perfusion. However, improvement in perfusion defects has been demonstrated only in patients exercised to the same cardiac workload on the post-EECP as the pre-EECP stress test. HYPOTHESIS: This study was to determine the effect of EECP on exercise capacity and myocardial perfusion by comparing results of maximal exercise radionuclide testing pre- and post-EECP treatment. METHODS: This prospective study included 25 patients with angina who had performed maximal symptom-limited exercise tolerance tests (ETT) with Bruce protocol and radionuclide perfusion single-photon emission computed tomography (SPECT) study prior to and at completion of EECP treatment. RESULTS: After 35 h of EECP, 23 patients (93%) improved by at least one functional angina class. There is a significant improvement in their total treadmill times (357 +/- 93 to 449 +/- 97 s, p < 0.001). There was a significant change in their peak double products, from 18,891 +/- 3,939 pre-EECP to 20,464 +/- 4,305 post-EECP ETT (p < 0.03). Pre EECP, 16 patients had ST-segment depression on their initial ETT. After EECP, 13 of these patients (80%) either no longer had ST depression or had a significant increase in their time to ST depression (229 +/- 52 to 315 +/- 60 s, p < 0.001). The radionuclide perfusion scores also showed a significant reduction in ischemic segments (16.36 +/- 10.52 to 14 +/- 10.9, p < 0.05). CONCLUSIONS: Patients treated with EECP demonstrated a reduction in angina symptoms, improvement in exercise capacity, increase in time to ST-segment depression, and decrease in perfusion defects despite performing at a higher workload.