Prospective screening of 5,615 high school athletes for risk of sudden cardiac death.

Sudden cardiac death among high school athletes is a very infrequent though tragic occurrence. Despite widespread preparticipation screening for known causes of this event, the frequency has not changed. The ECG is an acknowledged sensitive screening tool for the common causes of sudden cardiac death in young athletes. The specificity of the ECG in this setting is believed to be relatively low in young athletes for which reason, in part, it is not used. We added an ECG to the usual preparticipation screening. An echocardiogram was performed when screening was abnormal. Outcome measures of serious or potentially serious cardiovascular abnormalities were defined by the 16th Bethesda Conference. These abnormalities either preclude sports participation or require further testing before approval for participation in sports can be considered. Over 3 yr, 5,615 male and female high school athletes were screened prospectively from 30 different high schools in northern Nevada. Outcome measures were detected in 22 athletes or one per 255. Cardiac history led to detection of outcome measures in 0 athletes, auscultation/inspection in 1/6,000 athletes, blood pressure measurement in 1/1,000 athletes, and the ECG in 1/350 athletes. Specificity was 97.8% for an abbreviated cardiac history and auscultation/inspection and 97.7% for ECG. Overall, the ECG was a much more effective screening tool than cardiac history and auscultation/inspection in detecting cardiovascular abnormalities requiring further tests before approval for participation in sports could be given. ECG and cardiovascular history/ausculation/inspection had similar specificity ECG was efficiently performed on large groups of high school athletes.

Atrial sensing performance of the single-lead VDD pacemaker during exercise.

OBJECTIVES: The purpose of this study was to examine the atrial sensing performance of the single-lead VDD pacing system during exercise and concomitant changes in the amplitude of the atrial electrogram. BACKGROUND: Studies of conventional dual-chamber pacing have demonstrated an overall reduction in the atrial signal amplitude and a variable incidence of atrial undersensing during vigorous exercise. METHODS: The telemetered atrial electrogram and simultaneous surface electrocardiogram (ECG) were continuously recorded in 12 patients (mean age 70.8 years) with an implanted single-lead VDD pacing system during treadmill stress testing. The atrial signal amplitude was measured at peak exercise, and the patients were monitored for maintained atrial synchronized ventricular pacing during the entire exercise and recovery period. RESULTS: The atrial electrographic voltage decreased an average of 19.5% (p < 0.05) during peak exercise, and the reduced P wave amplitude ranged from 6.9% to 59.4% of the preexercise values in 8 of 12 patients. Three patients showed a modest increase in atrial signal amplitude, and one patient had no change. The telemetered electrogram displayed persistent and intact atrial synchronous ventricular pacing throughout the study period. CONCLUSIONS: Despite relatively low atrial signal amplitudes at rest and further decreases during exercise, the single-lead VDD pacemaker maintains reliable atrial tracking and ventricular pacing during vigorous exercise.

Hemodynamic response to intravenous enalaprilat in patients with severe congestive heart failure and mitral regurgitation.

The hemodynamic response 1 hour after 1.25 mg of intravenous (IV) enalaprilat was examined in 20 patients (mean age 75 years) with severe congestive heart failure (CHF) and mitral regurgitation (MR), secondary to ischemic heart disease (NYHA Class IV). Patients were classified into two groups based upon the magnitude of MR as derived from Doppler color flow imaging: Group I (n = 13) had severe MR and Group II (n = 7) had moderate MR. Acute therapy significantly reduced systemic vascular resistance index in both groups and provided effective afterload reduction. Although cardiac and stroke volume indices increased in both groups, an improved forward flow was significant only for Group I (cardiac index 2.2 +/- 0.5 to 2.7 +/- 0.5 l/min/m2, p < 0.02). The magnitude of MR, acutely reduced in all patients, was similarly significant only for Group I (56 +/- 10% to 31 +/- 12%, p < 0.01). The reduction of both pulmonary capillary wedge pressure and mean arterial pressure was significant for both groups. This study supports the use of IV enalaprilat, a parenteral angiotensin-converting enzyme (ACE) inhibitor, as an effective and rapidly acting vasodilator in the management of selected patients with chronic heart failure and MR who require immediate hemodynamic improvement.

Multifocal atrial arrhythmia--a frequent misdiagnosis? A correlative study using the computerized ECG.

All computerized ECGs taken over a 17-week study period were reviewed for the detection of multifocal atrial arrhythmia (MAA)--tachycardia or rhythm--and correlated with the diagnostic statement of the ECG computer system. MAA was identified by the authors in 96 of 11,610 (0.8%) computerized ECGs. In all instances, this specific arrhythmia was misclassified by the computer system as atrial fibrillation. Moreover, during the over-read, only 27.1% of ECGs were correctly diagnosed by the assigned electrocardiographers blinded to this study. MAA is not an uncommon atrial arrhythmia since it was identified in 14% of computerized ECGs interpreted as atrial fibrillation. This study supports the inference that MAA is indeed frequently misdiagnosed by most physicians and the need for improved ECG computer analysis programs for reliable detection of MAA.

The RSR' complex not related to right bundle branch block: diagnostic value as a sign of myocardial infarction scar.

An abnormal electrocardiographic (ECG) wave pattern--the RSR' complex--associated with a wide QRS (greater than or equal to 110 msec), unrelated to right bundle branch block (RBBB) or left bundle branch block (LBBB) was identified in 26 patients with old myocardial infarction. Patients were assigned to three groups: in group I (n = 13) the RSR' was present in the precordial leads; in group II (n = 9) the RSR' was present in the inferior limb leads; and in group III (n = 4) the RSR' was present in both. For each patient a severe segmental wall motion abnormality (akinetic in 16 and dyskinetic in 10 patients) consistent with myocardial infarction scar tissue was detected using the equilibrium radionuclide angiocardiogram (n = 24) and the two-dimensional echocardiogram (n = 2). The abnormal RSR' complex arises from a terminal conduction delay (dissimilar to either RBBB or LBBB using the vectorcardiogram) of left ventricular (LV) depolarization within impaired tissue surrounding the infarct scar. This study suggests that the RSR' complex, a unique mural conduction defect, although poorly sensitive has specific diagnostic value and reliability as a sign of myocardial infarction scar.