Effects of radiofrequency catheter ablation on regional myocardial blood flow. Possible mechanism for late electrophysiological outcome.

BACKGROUND We postulated that the late electrophysiological effects of radiofrequency (RF) ablation may be related to microvascular injury extending beyond the region of acute coagulation necrosis. METHODS AND RESULTS Eighteen RF lesions created in the left anterior descending coronary artery (LAD) perfusion bed of seven open chest anesthetized dogs were studied. The ablation electrode and surrounding myocardium were imaged using high-resolution two-dimensional echocardiography at x 4 magnification. After 60 seconds of RF delivery, sonicated albumin microbubbles (mean size, 4.3 microns) were injected into the LAD to measure regional myocardial perfusion, and time-intensity plots were generated from simultaneously acquired two-dimensional echocardiography images. The regions with persistent contrast effect on two-dimensional echocardiography were larger than the pathological lesions (mean cross-sectional area, 48.3 +/- 6.3 versus 19.3 +/- 4.7 mm2, respectively; P < .0001). The mean contrast transit rate in the area corresponding to the pathological lesion was 25 +/- 12% of that in the normal myocardium, but it was also reduced beyond the lesion, being 48 +/- 27% and 82 +/- 28% of normal, respectively, in the 3-mm and 3- to 6-mm circumferential rims surrounding the pathological lesion (P < .05). Electron microscopy performed in two additional dogs with similar lesions demonstrated the presence of ultrastructural damage to the microvascular endothelium well beyond the pathological lesion edge. CONCLUSIONS RF catheter ablation not only results in a marked reduction in blood flow within the acute pathological lesion but also causes reduced flow beyond the borders of the acute lesion because of microvascular endothelial cell injury. The progression or resolution of tissue injury within the region beyond the border of the pathological lesion may explain the late electrophysiological effects of RF ablation.

[1]  D. Haines,et al.  Adenosine and Verapamil‐Sensitive Ventricular Tachycardia Originating From the Left Ventricle: Radiofrequency Catheter Ablation , 1992, Pacing and clinical electrophysiology : PACE.

[2]  R K Jain,et al.  Differential response of normal and tumor microcirculation to hyperthermia. , 1984, Cancer research.

[3]  D D Watson,et al.  Tissue Heating During Radiofrequency Catheter Ablation: A Thermodynamic Model and Observations in Isolated Perfused and Superfused Canine Right Ventricular Free Wall , 1989, Pacing and clinical electrophysiology : PACE.

[4]  S S Segal,et al.  The behavior of sonicated albumin microbubbles within the microcirculation: a basis for their use during myocardial contrast echocardiography. , 1989, Circulation research.

[5]  R. Replogle,et al.  Leukocyte adherence in venules of rat skeletal muscle following thermal injury. , 1982, Microvascular research.

[6]  J I Hoffman,et al.  Blood flow measurements with radionuclide-labeled particles. , 1977, Progress in cardiovascular diseases.

[7]  B. Lerman,et al.  Delayed Success Following Radiofrequency Catheter Ablation , 1993, Pacing and clinical electrophysiology : PACE.

[8]  S. Kaul,et al.  Assessment of Risk Area During Coronary Occlusion and Infarct Size After Reperfusion With Myocardial Contrast Echocardiography Using Left and Right Atrial Injections of Contrast , 1993, Circulation.

[9]  R. Lazzara,et al.  Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current. , 1991, The New England journal of medicine.

[10]  J. Langberg,et al.  Diagnosis and cure of the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardias during a single electrophysiologic test. , 1991, The New England journal of medicine.

[11]  J. Langberg,et al.  Recurrence of conduction in accessory atrioventricular connections after initially successful radiofrequency catheter ablation. , 1992, Journal of the American College of Cardiology.

[12]  D. Krum,et al.  Selective Transcatheter Ablation of the Fast and Slow Pathways Using Radiofrequency Energy in Patients With Atrioventricular Nodal Reentrant Tachycardia , 1992, Circulation.

[13]  D D Watson,et al.  Assessment of Regional Myocardial Blood Flow with Myocardial Contrast Two-dimensional Echocardiography , 1989, Journal of the American College of Cardiology.

[14]  S. Badylak,et al.  Hyperthermia‐induced vascular injury in normal and neoplastic tissue , 1985, Cancer.

[15]  A R Jayaweera,et al.  Method for the quantitation of myocardial perfusion during myocardial contrast two-dimensional echocardiography. , 1990, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[16]  J. Langberg,et al.  Delayed Effects of Radiofrequency Energy on Accessory Atrioventricular Connections , 1993, Pacing and clinical electrophysiology : PACE.