Lee A. Biblo

Right ventricular outflow tract ventriculartachycardia: Detection of previously unrecognized anatomic abnormalities using cine magnetic resonance imaging☆

Abstract Objectives. This study attempted to determine whether cine magnetic resonance imaging (MRI), because of its unique ability to image the right ventricle, detects abnormalities in patients with right ventricular outflow tract ventricular tachycardia. Background. Right ventricular outflow tract ventricular tachycardia occurs in the absence of apparent structural heart disease. Methods. We compared cine MRI scans in 22 patients with right ventricular outflow tract ventricular tachycardia, 16 subjects without structural heart disease and 44 patients with other cardiovascular diseases. Echocardiography was performed in 21 patients with ventricular tachycardia. Results. All 22 patients with ventricular tachycardia had normal left ventricular function and no evidence of coronary artery disease. Cine MRI revealed right ventricular structural and wall motion abnormalities more often in patients with ventricular tachycardia (21 [95%] of 22) than in normal subjects (2 [12.5%] of 16, p

Tachycardia‐Induced Cardiomyopathy Secondary to Right Ventricular Outflow Tract Ventricular Tachycardia: Improvement of Left Ventricular Systolic Function After Radiofrequency Catheter Ablation of the Arrhythmia

Cardiomyopathy Secondary to RVOT VT. Introduction: Several reports describe development of cardiomyopathics secondary to supraventricular tachycardia. Few reports have described cardiomyopathies secondary to ventricular tachycardia.

Transcatheter Radiofrequency Ablation of Ventricular Tachycardia Following Surgical Correction of Tetralogy of Fallot

Ventricular arrhythmias occur in up to 13.5% of patients after tetralogy of Fallot repair. We describe a patient with a 30‐year history of recurrent ventricular tachycardia, which followed the surgical repair of tetralogy of Fallot. Findings at electrophysiological study were consistent with reentry involving an area of slow conduction in the right ventricular outflow tract. Following the transcatheter application of radiofrequency energy in the right ventricular outflow tract, ventricular tachycardia could no longer be induced and has not occurred spontaneously during follow‐up (28 months). Thus, transcatheter radiofrequency ablation is an acceptable therapeutic option in some patients with ventricular tachycardia after the surgical repair of tetralogy of Fallot.

Characterization of sinoatrial parasympathetic innervation in humans.

Sinoatrial Parasympathetic Innervation. Introduction: The response to sinoatrial parasympathetic nerve stimulation (shortened atrial refractoriness) was used to determine the atrial distribution of these nerve fibers in humans. We hypothesized that, in humans, parasympathetic nerves that innervate the sinoatrial node also innervate the right atrium and that the greatest density of innervation is near the sinoatrial nodal fat pad.

Endocardial Potential Mapping from a Noncontact Nonexpandable Catheter: A Feasibility Study

AbstractIn previous studies, we established methodology for reconstructing endocardial potentials, electrograms and isochrones from a non-contact intracavitary probe during a single beat. The probe was too large to be introduced percutaneously. Here we examine the possibility of similar mapping with a small multielectrode catheter that could be introduced percutaneously and does not expand inside the cavity. Cavity geometry and endocardial potentials were recorded in an isolated canine left ventricle. Simulated catheter probes were introduced into the cavity. Probe potentials were computed from the measured endocardial potentials and perturbed to include measurement noise, geometrical errors, and limited electrode density. Endocardial potentials were then reconstructed from the perturbed probe potentials and compared to the actual measured potentials. Of all probes simulated, a 3.0 mm (9F) catheter that assumes a curved geometry (e.g., a J shape) inside the cavity performed best (better than a larger 7.6 mm cylinder simulating an inflatable probe). Without bending, a straight cylindrical probe of the same size (9F, 3.0 mm) did not perform well. Sixty probe electrodes were needed for accurate reconstruction. The J-probe reconstruction was very robust in the presence of noise (10%) and of geometry errors (3 mm shift, 10° rotation). The results demonstrate the feasibility of accurate single-beat endocardial mapping using a 9F percutaneous multielectrode catheter that assumes a J shape in the cavity without the need for expansion (e.g., into a balloon or a “basket”). The robustness of the procedure to noise and geometrical errors suggests its applicability in the clinical EP laboratory and the possibility of determining probe position in vivo using current imaging modalities.

Salvage of Infected ICDs: Management Without Removal

During the 7‐year period from August 1986 to December 1993, 242 patients with malignant ventricular arrhythmias underwent 242 ICD implantations and 50 subcutaneous generator changes. Wound infections developed in 5 patients (1.7%): in 3 cases, after primary implantation (3/242 [1,2%]); and in 2 following a generator change (2/50 [4.0%]). This difference was not statistically significant. Infection developed at the generator pocket and became clinically manifest between 6 weeks and 40 months, postoperatively. Our treatment approach with the first patient consisted of simple debridement of the pocket and reimplantation of the existing generator. This led to recurrence, and the generator was safely explanted. In the remaining four patients, our approach has been that of local treatment, with wide debridement of the pocket, and placement of a closed irrigation system with continuous irrigation with a bacitracin, polymyxin, neomycin solution, and culture‐specific antibiotic therapy. We have successfully controlled the infection and salvaged the generator with this approach in all four patients, who are all alive and well at a mean follow‐up of 25.0 ± 17.3 months with no recurrence. The good results obtained in these patients suggest that the concept of total explantation of the infected ICD should be reassessed.

Evolving patterns in the surgical treatment of malignant ventricular tachyarrhythmias

The advent of the automatic implantable cardioverter defibrillator (AICD), generally viewed as a safe and effective intervention, has in some measure discouraged the use of electrophysiologically directed endocardial resection for intractable ventricular arrhythmias. We reviewed the records of 127 patients undergoing either AICD procedures or resection over a 6-year period. Thirty-day mortality was 5.6% (5/89 patients) for all AICD procedures, 10.7% (3/28) for AICD placement plus coronary artery bypass grafting, and 11.8% (4/34) for resection. These mortality figures are not significantly different. Patients undergoing resection were less likely to require antiarrhythmic agents than patients given an AICD (33% versus 61%). Survival at 2 years was 78% in the resection group and 72% in the AICD group. Survival at 4 years was still 78% in the resection group. Only 1 late sudden death occurred in the AICD group and none in the resection group. We conclude that resection continues to be a valuable alternative, offering a greater overall benefit at only slightly increased risk.

Endocardial stimulation of efferent parasympathetic nerves to the atrioventricular node in humans: Optimal stimulation sites and the effects of digoxin

AbstractThe purposes of this study were to identify optimal sites of stimulation of efferent parasympathetic nerve fibers to the human atrioventricular node via an endocardial catheter and to investigate the interaction between digoxin and vagal activation at the end organ. Methods: The ventricular rate was measured during atrial fibrillation, prior to and during parasympathetic nerve stimulation, in 8 patients taking digoxin and in 10 controls. High frequency electrical stimuli were delivered via an hexapolar or quadripolar electrode catheter, placed at the posteroseptal right atrium near the atrioventricular node (n=18 patients) or in the coronary sinus (n=12 of 18 patients). In 4 patients, stimulation was repeated after intravenous administration of 1 to 2[emsp4 ]mg of atropine. Results: Nerve stimulation prolonged the R-R interval in all patients. Stimulation close to the posteroseptal right atrium led to maximal atrioventricular nodal slowing. The mean R-R intervals at baseline and during parasympathetic nerve stimulation (60[emsp4 ]mA) from the posteroseptal right atrium and the proximal coronary sinus were 581±79[emsp4 ]ms, 2440±466, and 900±228[emsp4 ]ms respectively (p=0.0001). The response to nerve stimulation was greater in patients taking digoxin than in patients not taking the drug (p=0.02). Junctional rhythm occurred during nerve stimulation in 8/8 patients taking digoxin and 0/10 not taking the drug (p=0.0001). The response to stimulation was eliminated after atropine (p=0.01). Conclusions: Parasympathetic nerves to the atrioventricular node were stimulated from the proximal coronary sinus as well as the posteroseptal right atrium. Stimulation at the posteroseptal right atrium resulted in the greatest response, and digoxin enhanced this response. The augmented response suggests that an interaction may exist between parasympathetic stimulation and digoxin at the end organ.

New evidence that AV node slow pathway conduction directly influences fast pathway function.

Interaction Between the Slow and Fast Pathway. Introduction: Shortening of the AV node fast pathway effective refractory period (ERP) following successful slow pathway ablation may be a nonspecific effect of energy application at the AV junction or may be due to elimination of a direct effect of slow pathway conduction on the fast pathway.

Strategies in the surgical treatment of malignant ventricular arrhythmias: An 8-year experience

Introduction of the automatic implantable cardioverter defibrillator (AICD) has dramatically affected the surgical treatment of malignant ventricular tachyarrhythmias. The authors continue to perform electrophysiologically directed subendocardial resection (SER) of left ventricular (LV) scars in selected patients, and we revascularize (CABG) those patients undergoing AICD implantation who have significant myocardial ischemia. In an attempt to define the optimal role of each procedure, this report analyzes our 8-year experience with 348 consecutive patients treated surgically for these arrhythmias (SER since 1983 and AICD since 1986). All patients undergoing SER had organized ventricular tachycardia (VT) as a result of myocardial infarction, and most had LV aneurysms; of those undergoing AICD or AICD/CABG, 60% had VT, 15% had ventricular fibrillation, and 25% had both or were noninducible. The thirty-day mortality rate was 1.5% (3/197) for AICD, 5.4% (5/93) for AICD/CABG, and 8.6% (5/58) for SER; these mortality figures are not significant different. Late deaths in all groups were predominantly due to congestive heart failure, and actuarial survival as well as freedom from sudden death was similar between the groups at 4 years. Recurrent VT occurred in 167 of 282 (59%) of long-term survivors of AICD or AICD/CABG during follow-up and in nine of 53 (17%) of those with SER. Forty-eight per cent of survivors of AICD or AICD/CABG required antiarrhythmic medications, whereas only 11% of those with SER required antiarrhythmics. Long-term survival in each group is much higher than that reported for comparable patients with severe LV dysfunction treated medically. In those patients with organized VT and LV aneurysm who are judged able to survive the procedure, SER offers a high likelihood of cure rather than simple prevention of sudden death.