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ABSTRACT: Although radiofrequency catheter ablation has undergone explosive growth as the treatment for a variety of arrhythmias, a limiting factor with the existing catheter delivery system has been the relatively small size of the lesions, which appears to be in part due to coagulum formation around the catheter tip, producing a rise in impedance and limiting energy delivery. In order to test the hypothesis that infusion of saline during radiofrequency current application can increase the lesion size and decrease the incidence of impedance rise, ten dogs were each given two radiofrequency ablation lesions to the left ventricular endocardium. One of these lesions was delivered with a standard 7 French quadripolar catheter with a 2-mm tip, and the second was done with a 7 French luminal electrode catheter (also with a 2-mm tip) for the infusion of normal saline during the delivery of radiofrequency energy. Energy was delivered for 60 seconds at either 10 or 20 watts at two distinct sites in the left ventricle for each animal. Four to 7 days following ablation, the animals were sacrificed for pathological examination. The lesions created with the saline infusion catheter were significantly bigger than those produced with a standard catheter (7.3 x 7.0 x 5.1 vs 5.2 x 4.9 x 3.5 mm, respectively, P < 0.001). At the lower energy level (10 W), none of the animals with the saline infusion catheter experienced an impedance rise versus 3 of 5 of the animals in whom the standard catheter was used.(ABSTRACT TRUNCATED AT 250 WORDS)
Pacing and Clinical Electrophysiology 05/1995; 18(5 Pt 1):1022-7. · 1.35 Impact Factor
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ABSTRACT: We examined the clinical and echocardiographic characteristics of patients undergoing aortic valve replacement for aortic stenosis whose continuous wave Doppler studies showed abnormal intracavitary flow acceleration.
The clinical and Doppler echocardiographic records of 53 consecutive patients undergoing aortic valve replacement for aortic stenosis were reviewed. Doppler echocardiography was performed at a mean of 6.6 days (range, 0-22 days) after surgery. Thirteen patients (group 1) had a dagger-shaped high-velocity systolic flow signal indicative of abnormal intracavitary flow acceleration on their postoperative Doppler study; group 2 comprised 40 aortic stenosis patients who underwent aortic valve replacement but had no postoperative evidence of abnormal intracavitary flow acceleration. Group 1 postoperative abnormal intracavitary flow velocities ranged from 1.8 to 6.8 m/sec (mean, 4.9 +/- 0.9 m/sec): Resulting dynamic gradients ranged from 10 to 184 mm Hg (mean, 104.6 +/- 32 mm Hg). Compared with group 2, group 1 patients had a distinctive ventricular geometry with more-pronounced hypertrophy, smaller cavities, and higher ejection fraction. Systolic anterior motion of the mitral valve did not accompany abnormal intracavitary flow acceleration in any patient. Six of 13 group 1 patients suffered postoperative hemodynamic compromise characterized by severe hypotension despite adequate pulmonary capillary wedge pressures; group 1 postoperative mortality was significantly greater than that seen in group 2 patients (38% versus 12%, p less than 0.05).
Abnormal intracavitary flow acceleration after aortic valve replacement for severe aortic stenosis is associated with a distinctive ventricular geometry and supernormal systolic function but not systolic anterior motion of the mitral valve. Such flow acceleration appears to be a marker for increased postoperative morbidity and mortality. Preoperative and postoperative Doppler echocardiography may be useful in risk stratification and guiding therapy.
Circulation 10/1992; 86(3):926-36. · 14.74 Impact Factor
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ABSTRACT: In this report we describe a patient who died during programmed ventricular stimulation due to a rupture of the left ventricular free wall at the site of a recent myocardial infarction. The patient was a 75-year-old male who presented with an extensive anterior wall myocardial infarction complicated by sustained ventricular tachycardia occurring 8 days after admission. Cardiac catheterization revealed total occlusion of left anterior descending coronary artery and an anteroapical aneurysm. The patient died due to electromechanical dissociation during electrophysiological testing 11 days after myocardial infarction. Postmortem examination showed a rupture of the left ventricular free wall at the site of the myocardial infarction and distant from the site of catheter placement. It is suggested that caution be taken in choosing patients for electrophysiological studies who have had recent large myocardial infarctions with ventricular aneurysm.
Pacing and Clinical Electrophysiology 06/1992; 15(5):722-5. · 1.35 Impact Factor
