The cardiointegram: detection of coronary artery disease in males with chest pain and a normal resting electrocardiogram.

The cardiointegram is a non-invasive technique for the analysis of the electrical signals of the heart obtained by a transformation of the voltage vs. time format by a series of integrations. This multicenter study compares the results of the cardiointegram with coronary arteriography in 140 male patients with chest pain and a normal resting electrocardiogram. The cardiointegram was determined on two resting complexes of Leads I, II, V4, V5 and V6 and called abnormal if greater than or equal to four of ten complexes were abnormal, i.e., fell outside of a previously determined template of normality. The sensitivity was 73% and specificity was 78% for the diagnosis of occlusive coronary artery disease. When greater than or equal to five of ten abnormal complexes were used as the cut-off for an abnormal test and "equivocal" results (four of ten abnormal, n = 18) were excluded from analysis there was a sensitivity of 69% and specificity of 88%. Thirty-seven of 38 patients (97%) with an abnormal cardiointegram and a positive exercise stress test had coronary artery disease. Thus, the cardiointegram appears to be a useful non-invasive test for the detection of coronary artery disease in males with chest pain and a normal resting electrocardiogram in whom the diagnosis of coronary artery disease is being considered.

Myopotential interference with DDD pacemakers: endocardial electrographic telemetry in the diagnosis of pacemaker-related arrhythmias.

Skeletal myopotentials may inhibit the output of unipolar demand ventricular pacemakers, resulting in protracted episodes of asystole in susceptible patients. The new DDD-mode pacemakers have, in addition to a unipolar ventricular lead, a unipolar atrial lead to enable atrioventricular sequential or atrial synchronous function. During clinical investigation of a new dual-unipolar cardiac pacing system programmed to operate in the DDD mode (Pacesetter AFP models 281 and 283), 6 patients were noted (5 men and 1 woman, aged 22 to 68 years) who manifested paroxysmal acceleration of ventricular pacing rate approaching the maximal tracking rate. Two patients also had abrupt slowing or cessation of ventricular output. With the use of atrial electrographic recordings (obtained with telemetry), the following mechanisms of rate change were found: myopotential tracking, myopotential inhibition, interference-mode asynchronous operation, sudden increases in sinus rate, and pacemaker-mediated reentrant tachycardia. In all patients, reprogramming of the implanted devices, based on telemetered atrial electrography, resulted in disappearance of the arrhythmias and loss of symptoms while maintaining the DDD pacing mode. Thus, several mechanisms of rhythm disturbances are peculiar to dual-chamber cardiac pacing systems that use unipolar electrodes. Endocardial telemetry combined with extensive programming capability offers the best opportunity for proper diagnosis and management of these problems.

Microbubbles have intracardiac velocities similar to those of red blood cells.

The slope of an individual contrast trajectory on M-mode echocardiography represents the projection of the intracardiac velocity vector of a microbubble in the direction of the sound beam. Doppler echocardiography measures this projection of red blood cell velocity. To ascertain whether microbubbles have similar intracardiac velocities to those of red blood cells, 11 subjects were studied during intravenous injections of 5% dextrose solution. The flow across the tricuspid and pulmonary valves was examined. Microbubble velocity was measured by M-mode contrast slope analysis and simultaneously by Doppler technique. Results from both methods were correlated with red blood cell velocity measured by Doppler recording at the same time in the cardiac cycle, shortly before appearance of contrast medium (3 to 8 beats before the corresponding contrast velocity measurements). In all subjects, 10 sets of three velocities each (M-mode slope and Doppler data before and during contrast injection) were obtained for each valve. Visual inspection of the Doppler tracings showed similar velocity profiles before and during contrast appearance; the signal intensity was greater with contrast. Quantitatively, microbubble velocity assessed by M-mode trajectory slopes correlated well with the Doppler-derived velocity of red blood cells (r = 0.98, p less than 0.001, slope of the regression line = 0.99, standard error of the estimate = 7 cm/s). Doppler velocities measured with and without contrast medium showed a similar correlation (r = 0.99, p less than 0.001, slope of regression = 1.01, standard error of the estimate = 6 cm/s). In individual subjects, the correlation coefficient between microbubble and red blood cell velocities ranged form 0.978 to 0.998.(ABSTRACT TRUNCATED AT 250 WORDS)