Aortic Leaflet Perforation During Radiofrequency Ablation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73537/1/j.1540-8159.1991.tb02732.x.pd

Management of Nonsustained Ventricular Tachycardia Guided By Electrophysiological Testing

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73206/1/j.1540-8159.1993.tb04578.x.pd

Comparison of Fixed Burst Versus Decremental Burst Pacing for Termination of Ventricular Tachycardia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72440/1/j.1540-8159.1993.tb01531.x.pd

Effects of quinidine and amiodarone on blood pressure during rapid ventricular pacing in coronary artery disease

The hemodynamic response to ventricular tachycardia is an important determinant of prognosis.1 Many factors determine the hemodynamic response to ventricular tachycardia, including (1) the rate of the ventricular tachycardia,2,3 (2) systolic and diastolic ventricular function,4,5 and (3) the neurohumoral response to the arrhythmia.6,7 Antiarrhythmic drugs such as quinidine and amiodarone may either improve hemodynamics during ventricular tachycardia by slowing the rate of the tachycardia, or may impair the hemodynamic response to ventricular tachycardia by decreasing ventricular contractility, blunting the neurohumoral response to the tachycardia, or by causing vasodilation.8-14 No prior studies have evaluated the effect of antiarrhythmic drugs on the hemodynamic response to ventricular tachycardia independent of their effects on the rate of the tachycardia. The objective of this study was to determine the relative effects of quinidine and amiodarone on the blood pressure (BP) response to rapid ventricular pacing in humans. Previous studies have demonstrated that the BP response during ventricular tachycardia and during ventricular pacing are similar.2 Therefore, in this study ventricular pacing was used to assess the effects of antiarrhythmic drugs on the BP response independent of heart rate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29774/1/0000113.pd

Comparison of responses to isoproterenol and epinephrine during head-up tilt in suspected vasodepressor syncope

Head-up tilt is known to play an important role in establishing the diagnosis of vasodepressor syncope in patients with syncope of unknown etiology.1-5 Although passive head-up tilt alone may trigger a vasodepressor response, recent studies show that an infusion of isoproterenol significantly increases the sensitivity of head-up tilt in reproducing vasodepressor syncope.1-5 However, isoproterenol is not endogenously produced and the role of endogenous catecholamines, such as epinephrine, in provoking vasodepressor syncope is unknown. Therefore, we compared the responses to isoproterenol and epinephrine during head-up tilt in patients suspected of having vasodepressor syncope.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29504/1/0000590.pd

Effect of verapamil on infranodal conduction in patients with baseline His-Purkinje conduction delay

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29672/1/0000761.pd

Noncapturing stimuli during the basic drive shorten ventricular refractoriness

Studies of ventricular programmed stimulation in animals1 and a recent study in humans1 showed that increasing the stimulation intensity of the basic drive train (S1) shortened the effective refractory period (ERP). This effect was independent of the intensity of the extrastimulus (S2). The mechanism of this shortening of refractoriness by high-current intensity is unknown. The effect disappears when the sites of pacing and extrastimulation are separated by >2 cm,1 suggesting that high-current stimulation shortens refractoriness through changes in the sequence of local activation. Local sympathetic activation may also play a role, because autonomic blockade significantly attenuates the shortening in refractoriness that occurs with an increase in the strength of the current of the basic drive train.2 This study better defines the mechanism by which intense stimulation shortens refractoriness. High-current intensity stimuli were applied during the absolute refractory period of the basic drive train during measurement of ERP. This allowed evaluation of the effect of stimulation intensity on ventricular refractoriness independent of changes in local activation sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29090/1/0000125.pd

Relation between efficacy of radiofrequency catheter ablation and site of origin of idiopathic ventricular tachycardia

The results of radiofrequency catheter ablation of ventricular tachycardia (VT) in patients without structural heart disease are reported. Particular attention was focused on the relation between efficacy and the site of origin of the VT. Eighteen consecutive patients (5 women and 13 men; mean age 41 +/- 13 years) with idiopathic VT underwent catheter ablation using radiofrequency energy. Sites for radiofrequency energy delivery were selected on the basis of pace mapping. A follow-up electrophysiologic test was performed 1 to 3 months after the ablation procedure. Twenty VTs were induced. Radiofrequency catheter ablation was successful in eliminating all 10 VTs originating from the right ventricular outflow tract, and 5 of 10 from other sites in the left or right ventricle. There were no complications. The duration of ablation sessions was shorter, the frequency of identifying a site resulting in an identical pace map was higher, and the efficacy of catheter ablation was greater for VTs originating from the right ventricular outflow tract than for those from other locations. The results of this study demonstrate that radiofrequency catheter ablation of idiopathic VT is safe and effective. The efficacy of the procedure is dependent on the site of origin of the VT, with the efficacy being greater for VTs originating from the outflow tract of the right ventricle than for those from other locations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30894/1/0000563.pd

Outcome of endocardial resection in 33 patients with coronary artery disease: Correlation with ventricular tachycardia morphology

The results in 33 patients with ventricular tachycardia (VT) treated by endocardial resection were reviewed, with special emphasis on the presence of single or multiple morphologies preoperatively and intraoperatively. Multiple VT morphologies were induced in 16 patients and a single VT morphology was induced in the remaining 17. Intraoperative programmed stimulation failed to induce VT in eight patients and visually-directed endocardial resection was performed. The remaining patients underwent map-guided resection. The surgical success rate did not correlate with any morphologic characteristics of the VT, such as bundle branch block pattern or axis. In addition, concordance of VT morphologies preoperatively and intraoperatively before resection did not correlate with the surgical success rate. However, patients in whom multiple morphologies of VT were induced intraoperatively had a significantly higher success rate (100%) compared with those patients in whom only a single morphology was induced intraoperatively (50%, p < 0.05). Long-term follow-up was maintained in 26 patients. Ventricular tachycardia recurred in two patients and VF recurred in two others who did not have inducible VT 1 week after endocardial resection. In conclusion, neither the preoperative morphologic characteristics of VT nor discordance between the morphologies of VT induced preoperatively and in the operating room influenced the outcome of endocardial resection. However, the surgical success rate is higher when multiple morphologies of VT are inducible in the operating room than when only one VT morphology is inducible.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29715/1/0000049.pd