Clinical implication of surface morphology of ventricular premature contractions

Radiofrequency catheter ablation for management of symptomatic ventricular ectopic activity

OBJECTIVES

This study assessed the useful role of intracardiac mapping and radiofrequency catheter ablation in eliminating drug-refractory monomorphic ventricular ectopic beats in severely symptomatic patients.

BACKGROUND

Ventricular ectopic activity is commonly encountered in clinical practice. Usually, it is not associated with life-threatening consequences in the absence of significant structural heart disease. However, frequent ventricular ectopic beats can be extremely symptomatic and even incapacitating in some patients. Currently, reassurance and pharmacologic therapy are the mainstays of treatment. There has been little information on the use of catheter ablation in such patients.

METHODS

Ten patients with frequent and severely symptomatic monomorphic ventricular ectopic beats were selected from three tertiary care centers. The mean frequency +/- SD of ventricular ectopic activity was 1,065 +/- 631 beats/h (range 280 to 2,094) as documented by baseline 24-h ambulatory electrocardiographic (ECG) monitoring. No other spontaneous arrhythmias were documented. These patients had previously been unable to tolerate or had been unsuccessfully treated with a mean of 5 +/- 3 antiarrhythmic drugs. The site of origin of ventricular ectopic activity was accurately mapped by using earliest endocardial activation time during ectopic activity or pace mapping, or both.

RESULTS

During electrophysiologic study, no patient had inducible ventricular tachycardia. The ectopic focus was located in the right ventricular outflow tract in nine patients and in the left ventricular posteroseptal region in one patient. Frequent ventricular ectopic beats were successfully eliminated by catheter-delivered radiofrequency energy in all 10 patients. The mean number of radiofrequency applications was 2.6 +/- 1.3 (range 1 to 5). No complications were encountered. During a mean follow-up period of 10 +/- 4 months, no patient had a recurrence of symptomatic ectopic activity, and 24-h ambulatory ECG monitoring showed that the frequency of ventricular ectopic activity was 0 beat/h in seven patients, 1 beat/h in two patients and 2 beats/h in one patient.

CONCLUSIONS

Radiofrequency catheter ablation can be successfully used to eliminate monomorphic ventricular ectopic activity. It may therefore be a reasonable alternative for the treatment of severely symptomatic, drug-resistant monomorphic ventricular ectopic activity in patients without significant structural heart disease.

The importance of derived 12-lead electrocardiography in the interpretation of arrhythmias detected by Holter recording

Holter monitoring has been used extensively for the detection, diagnosis, and evaluation of therapy for cardiac arrhythmias. The availability of three-channel monitors allows for the recording of vectorcardiographic leads X, Y, and Z. One method, which was recently described by Dower et al., (J Electrocardiol 1988;21:5182-7), uses modified vectorcardiographic leads and allows for the acquisition of a derived 12-lead ECG of selected rhythm strips during the recording. In the present study, we evaluated the usefulness of the derived 12-lead ECG in the detection of P-wave and ST-segment shifts, assessment of QRST changes, and distinction between ventricular ectopic and aberrant supraventricular complexes. Our preliminary findings indicate that careful analysis of the derived 12-lead ECG provides additional information for a more accurate diagnosis of arrhythmias that are detected by the Holter monitor. The clinical importance and cost-effectiveness of the derived 12-lead ECG needs further evaluation.

Sites of origin of ventricular premature beats in patients with and without cardiovascular disease evaluated by body surface mapping

The site of origin of ventricular premature beats (VPBs) was estimated by QRS maps and its distribution in two patient groups was studied. VPB origin was determined by comparing the body surface map of VPBs with that during electrical stimuli applied at various sites of the ventricle. Subjects were 100 patients without obvious underlying cardiovascular disease (Group N) and 289 patients with various heart diseases (Group D). Nine sites of origin of VPB were identified. In group N, VPBs of right ventricular origin were noted in 69%, those of left ventricular origin in 6%. There was a relatively high incidence of VPBs with foci estimated to be the divisions of the left bundle branch, and the age of patients with these VPBs was young. In Group D, VPBs of left ventricular origin showed a higher incidence (34.6%) and those of right ventricular origin a lower incidence (41.2%) than those in group N. The data suggest that VPBs originating from the apex and base of the ventricle strongly indicate the presence of basic heart disease and that VPBs originating in or near the divisions of the left bundle branch in younger subjects do not necessarily indicate cardiac disease.

Localization of the site of ventricular premature complexes by radionuclide angiographic phase imaging

To investigate whether gated radionuclide angiographic phase imaging is useful for visually displaying the origin of ventricular premature complexes (VPCs), 82 patients were studied by gating only VPCs. The VPC "origin" by the scintigraphic method was defined as the area of earliest phase and was compared with that predicted by 12-lead electrocardiographic criteria in all patients and to invasive electrophysiologic mapping in 10. Separating the right ventricle into 3 and the left ventricle into 4 segments, the phase imaging method and the electrocardiographic criteria agreed as to ventricle of VPC origin in 69 patients (84%) and segment of origin within each ventricle in 46 (56%). When baseline ventricular wall motion was analyzed, the 2 methods agreed to the ventricle of VPC origin in 31 of 33 patients (94%) with normal wall motion, 20 of 23 (87%) with segmental wall motion abnormalities and 19 of 26 (73%) with diffuse wall motion abnormalities. Agreement between the 2 methods as to specific segmental localization of the arrhythmia focus was noted in 21 of 33 patients (64%) with normal wall motion, 11 of 23 (48%) with segmental wall motion abnormalities and 12 of 26 (46%) with diffuse hypocontractility. In the 10 patients with endocardial mapping studies, the phase imaging technique confirmed the segment of VPC origin in all 10; the electrocardiographic method was accurate in 8. Thus, gated radionuclide angiographic phase imaging methods may be of value in noninvasively defining the origin of spontaneous VPCs. The visual format allows ready interpretation of the arrhythmia origin, and there may be an advantage to this approach over electrocardiographic morphometric criteria.