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His-Purkinje System (his-purkinje + system)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Identification and Ablation of Three Types of Ventricular Tachycardia Involving the His-Purkinje System in Patients with Heart Disease

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2004
GUSTAVO LOPERA M.D.
Introduction: Ventricular tachycardia (VT) with involvement of the His-Purkinje system (HPS) can be difficult to recognize in patients with heart disease, but it may be particularly susceptible to ablation targeting the HPS. This study defines the incidence and types of HPS involvement in VT. Methods and Results: Involvement of the HPS was sought during electrophysiologic study with catheter mapping in 234 consecutive patients referred for catheter ablation of recurrent VT associated with heart disease. HPS VT was observed in 20 (8.5%) patients (mean ejection fraction 29%± 17%); in 9 (11%) of 81 patients with nonischemic heart disease and 11 (7.1%) of 153 patients with coronary artery disease (P = NS). Three types of HPS VT were observed: 16 patients (group 1) had typical bundle branch reentry, 2 patients (group 2) had bundle branch reentry and interfascicular reentry, and 2 patients (group 3) had VT consistent with a focal origin in the distal HPS. In all three groups, the VT QRS had morphologic similarity to the sinus rhythm QRS. Ablation of HPS VT was successful in all patients in whom it was attempted but produced high-degree AV block in 6 (30%). In 12 patients (60%), other VTs due to reentry through scar also were inducible. Conclusion: Involvement of the HPS in VT associated with heart disease has three distinct clinical forms, all of which are susceptible to ablation. Ablation often is not sufficient as the sole therapy due to other induced VT's and conduction abnormalities, requiring pacemaker and/or defibrillator implantation. (J Cardiovasc Electrophysiol, Vol. 15, pp. 52-58, January 2004) [source]

Connexin40-Deficient Mice Exhibit Atrioventricular Nodal and Infra-Hisian Conduction Abnormalities

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2000
BRIAN A. VANDERBRINK B.S.
AV Nodal and Infra-Hisian Conduction in Cx40 Mice. Introduction: Previous electrophysiologic investigations have described AV conduction disturbances in connexin4(Cx40)-deficient mice. Because expression or(Cx40 occurs predominantly in the atria and His-Purkinje system of the mouse heart, the AV conduction disturbances were thought to be secondary to disruption in His-Pnrkinje function. However, the lack of a His-bundle electrogram recording in the mouse has limited further investigation of the importance of Cx40. Using a novel technique to record His-bundle recordings in Cx40-deficient mice, we define the physiologic importance of defciencies in Cx40. Methods and Results: Ten Cx40 -/- mice and 11 Cx40+/+ controls underwent a blinded, in vivo, closed chest electrophysiology study at 9 to 12 weeks of age. In the Cx40+/+ mice, the PR interval was significantly longer compared with Cx40+/+ mice (44.6 ± 6.4 msec vs 36.0 ± 4.1 msec, P = 0.002). Not only the HV interval (14.0 ± 3.0 msec vs 10.4 ± 1.2 msec, P = 0.003) but also the AH interval (33.2 ± 4.8 msec vs 27.1 ± 3.7 msec, P = 0.006), AV Wenckebach cycle lengths, and AV nodal effective and functional refractory periods were prolonged in Cx40 -/- compared with Cx40+/+ mice. Conclusion: Cx40-deficient mice exhibit significant delay not only in infra-Hisian conduction, as would be expected from the expression of Cx40 in the His-Purkinje system but also in the electrophysiologic parameters that reflect AV nodal conduction. Our data suggest a significant role of Cx40 in atrionodal conduction and/or in proximal His-bundle conduction, [source]

Correlation of Electrical and Mechanical Reverse Remodeling after Cardiac Resynchronization Therapy

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2009
Swapna Kamireddy M.D.
Background: Cardiac resynchronization therapy (CRT) improves clinical outcome in many patients with refractory heart failure (HF). This study examined whether CRT is associated with reverse electrical remodeling by surface electrocardiogram (ECG). Methods: Consecutive CRT recipients at the University of Pittsburgh Medical Center with >90 days of follow-up were included in this analysis. ECG data were abstracted from medical records. Subjects with a relative increase of ,15% in left ventricular ejection fraction (LVEF) after CRT were considered responders. Results: A total of 113 patients (age 69 ± 11 years, men 70%, white 92%) were followed for a mean duration of 407 ± 290 (92,1439) days. Overall, LVEF increased after CRT (29 ± 13% vs 24 ± 9%; P < 0.01) and 50% of patients were responders. The mean native QRS interval among responders was higher than in nonresponders (163 ± 32 ms vs 148 ± 29 ms; P < 0.01). More than 3 months after CRT, there was no change in the paced QRS duration compared to baseline. Paced QRS duration, however, decreased among responders and increased among nonresponders and was significantly different by response status (P < 0.001). There was a significant correlation between increase in LVEF and decrease in paced QRS width in the overall population (r =,0.3; P < 0.01). Conclusions: Among responders to CRT, the paced QRS width decreases significantly, whereas it increases among nonresponders. Given the paced nature of the QRS, the improved conduction probably reflects enhanced cell-to-cell coupling after CRT as opposed to improved conduction within the His-Purkinje system. These findings have significant implications as to the mechanisms of benefit from CRT. [source]