Endocardial mapping in humans in sinus rhythm with normal left ventricles: activation patterns and characteristics of electrograms.

Abstract

Endocardial catheter mapping was performed in 15 patients in sinus rhythm who had no evidence of structural heart disease and normal left ventricles. Mapping was performed with the use of 10 mm interelectrode distance from various left ventricular endocardial sites. In 10 patients a quantitative analysis of electrographic amplitude, duration, and amplitude/duration ratio was performed. The normal left ventricular bipolar electrograms had an amplitude of greater than 3 mV, a duration of less than 70 msec, and an amplitude/duration ratio of greater than 0.045. Local activation times were also assessed in the 15 patients. This analysis revealed two endocardial breakthrough sites, one on the midinferior septum and a second on the anterior wall near the insertion of the anterior papillary ittuscle. We therefore have defined normal quantitative characteristics of left ventricular bipolar electrograms and the normal left ventricular activation sequence in the intact normal human left ventricle. Circulation 70, No. 1, 37-42, 1984. NORMAL left ventricular endocardial activation and electrographic characteristics in man have not previously been described in vivo. It is imperative to establish normal guidelines if this technique is to be used to evaluate conduction defects, infarction, or arrhythmias. Our study was designed to characterize the electrograms and sequence of ventricular activation obtained during sinus rhythm by catheter endocardial mapping of the normal human left ventricle. MethodsPatient population. Fifteen patients referred to the Hospital of the University of Pennsylvania for electrophysiologic evaluation underwent sinus rhythm endocardial mapping during the course of their examinations. There were eight male and seven female subjects with a mean age of 30 years (range 17 to 64).In no patient was there evidence of structural heart disease. All had normal M mode and two-dimensional echocardiograms. Ten of the 15 patients had normal left ventricular radionuclidegated blood pool scans and in 10 (including five who did not undergo radionuclide-gated blood pool scanning) of the 15 patients results of left heart catheterization and coronary angiographic examination were normal. All patients had normal PR and QRS intervals and normal electrical axes. In two patients intermittent long QT intervals were documented (one drug-related and the other idiopathic). Electrocardiograms of both patients were normal at the time of endocardial mapping. There was no evidence of a preexcitation syndrome in any patient, as determined clinically and by laboratory testing. Electrophysiologic studies were performed to determine the presence or absence of a variety of arrhythmias. Three patients had sustained ventricular tachycardia in the absence of structural heart disease.Electrophysiologic study. Studies were performed in patients in the nonsedated, postabsorptive state after informed written consent had been obtained. Antiarrhythmic drug therapy was discontinued at least five half-lives before endocardial mapping. ...

Ventricular Unipolar Potential in Radiofrequency Catheter Ablation of Idiopathic Non-Reentrant Ventricular Outflow Tachycardia

“…The mean amplitudes of the local unipolar and bipolar electrograms were 4.5 ± 0.5 mV and 2.6 ± 0.6 mV, respectively. 12,13) The mean ∆V/∆t of the unipolar electrograms during the initial 10 ms was 1.2 ± 0.3 V/s, and the mean amplitude of the elevated ST segment of the unipolar electrograms 1.7 ± 0.3 mV. Sensitivity and specificity of electrophysiologic parameters: The sensitivity and specificity of the QS-pattern unipolar potential, pacemapping score and V o -QRS o interval for successful ablation are shown in Table III.…”

Mark E Josephson: A Tribute to His Work on Ventricular Arrhythmias

“…Abnormal, late, split and fractionated electrograms, diastolic activation and continuous electrical activity would become part of the electrophysiology lexicon in describing the VT substrate and circuit. [1][2][3] This early work also revealed the subendocardium to be a critical component of most post-MI VTs. This would lead to the surgical 'peeling' of the subendocardial layer of infarcted myocardium extending from the edge of the more densely scarred aneurysm to eliminate VT. 4,5 The 'Pennsylvania Peel' was established as the surgical technique to cure infarct-related VT.…”

“…Abnormal, late, split and fractionated electrograms, diastolic activation and continuous electrical activity would become part of the electrophysiology lexicon in describing the VT substrate and circuit. [1][2][3] This early work also revealed the subendocardium to be a critical …”

Effects of lidocaine and procainamide on normal and abnormal intraventricular electrograms during sinus rhythm.

“…The duration of the low-amplitude activity of the abnormal left ventricular sites was measured from the fixed gain, as described previously. 5 The maximum duration of the QRS complex was measured from lead I, aVF, or V1. Electrograms were recorded during sinus rhythm and after 15 beats of pacing at a cycle length of 600 msec.…”