ABSTRACT
In a preliminary study comparing 7 sets of bipolar leads with standard modified V1 and V5 leads, a vertical sternal lead system with the negative lead just below the suprasternal notch, and the positive lead over the xiphoid had the greatest P-wave area. In the current study, the vertical sternal and modified V1 leads were obtained simultaneously using 2-channel ambulatory electrocardiographic recorders in 50 consecutive patients undergoing diagnostic ambulatory electrocardiography for suspected arrhythmias. The vertical sternal lead provided tracings with a larger P-wave area compared with that of the modified V1 (0.58 +/- 0.44 vs 1.23 +/- 0.69 mm2; p less than 0.0001), and a greater QRS complex (9.23 +/- 4.16 vs 11.78 +/- 4.90 mm; p = 0.006). During premature atrial contractions and supraventricular tachycardia, P-wave visibility was significantly better in the sternal lead than in V1 (p less than 0.001). Furthermore, sternal lead tracings were superior with regard to overall quality and noise level. It is suggested that the vertical sternal lead replace the currently used modified V1 during ambulatory electrocardiographic monitoring. This lead system in conjunction with the standard modified V5 lead should be useful in the differential diagnosis of atrial arrhythmias.
Subject(s)
Arrhythmias, Cardiac/diagnosis , Electrocardiography, Ambulatory/methods , Adolescent , Adult , Aged , Aged, 80 and over , Chi-Square Distribution , Child , Child, Preschool , Diagnosis, Differential , Female , Humans , Infant , Male , Middle Aged , PrevalenceABSTRACT
The usual lead systems for ambulatory ECG monitoring (AECG) used in the evaluation of arrhythmias is a modified bipolar V-1 and V-5. A comparison of various lead systems to enhance the detection of atrial activity (p waves) has not been reported. We evaluated various surface lead systems in 12 subjects comparing p waves recorded at 20 mm/mV and 50 mm/sec. We compared p wave area, amplitude, and duration from modified bipolar V1 and V5 as well as seven nonstandard leads recorded on a AECG monitor. Of the seven nonstandard leads, a vertical sternal lead, with the negative pole just below the suprasternal notch and the positive pole at the xiphoid process, had the largest area (1.46 +/- 0.65 mm2), and also had a greater area than the standard V1 (0.88 +/- 0.45 mm) and V5 (1.06 +/- 0.49 mm2) lead system (P less than 0.01). We conclude that the bipolar vertical sternal lead system provides a larger p wave area than seven nonstandard bipolar lead systems and the two standard lead systems currently used in AECG monitoring. Replacement of the modified bipolar V1 lead with a vertical sternal lead should improve the recognition of atrial activity and, therefore, enhance the diagnosis of cardiac arrhythmias.
Subject(s)
Atrial Function/physiology , Electrocardiography, Ambulatory/methods , Adult , Arrhythmias, Cardiac/diagnosis , Electrodes , Evaluation Studies as Topic , Female , Humans , Male , Pilot ProjectsSubject(s)
Arrhythmias, Cardiac , Cardiomyopathies , Tachycardia , Arrhythmias, Cardiac/diagnosis , Arrhythmias, Cardiac/epidemiology , Arrhythmias, Cardiac/therapy , Biopsy , Cardiomyopathies/diagnosis , Cardiomyopathies/epidemiology , Cardiomyopathies/therapy , Echocardiography , Electrocardiography , Electrocoagulation , Electrophysiology , Humans , Prevalence , Prognosis , Radionuclide Angiography , Tachycardia/diagnosis , Tachycardia/epidemiology , Tachycardia/therapyABSTRACT
Differentiation between primary and secondary (caused by acute myocardial infarction) ventricular fibrillation has important therapeutic and prognostic implications. The diagnosis of myocardial infarction is based on clinical, ECG, and creatine kinase MB isoenzyme (MBCK) activity. Enzymatic criteria might not be able to confirm the diagnosis of myocardial infarction after recent cardioversion. The routine use of electrophysiologic studies involving the induction and termination of ventricular dysrhythmias provides a setting in which enzyme release as a result of cardioversion alone can be examined. Therefore a systematic investigation of the magnitude and time course of creatine kinase (CK) and MBCK release was performed after termination of ventricular dysrhythmias in 57 patients undergoing electrophysiologic studies. Of patients requiring external cardioversion, only 50% had an elevation in CK and MBCK activity. Elevation when present corrected with the number of shocks and cumulative energy delivered. The magnitude of MBCK release exceeded 10% of the total CK activity in 9% of observations. Pace-termination of ventricular tachycardia did not result in enzyme release. Arrhythmia characteristics, coronary artery disease, and left ventricular function did not affect the magnitude of the time course of enzyme release. These data suggest that cardioversion with multiple shocks may result in a component of MBCK release, and thus a false positive diagnosis of primary acute myocardial infarction may be made by relying exclusively on the enzyme release pattern.
