Endocardial mapping of ventricular tachycardia in the intact human ventricle. III. Evidence of multiuse reentry with spontaneous and induced block in portions of reentrant path complex

Abstract

These observations enlarge and extend our knowledge of the functional repertoire of complex reentrant tracts that occur in infarct-related ventricular tachycardia. The use of common portions of a reentrant tract by several tachycardias is confirmed. Utilization of alternate pathways can account for changes in configuration and cycle length. Spontaneous and induced block can occur at points of entry and exit in a reentrant tract and may identify optimal targets for ablation attempts. Further advances will require greater emphasis on diastolic activation mapping.

Onset of Reentrant Ventricular Tachycardia Modulated by Variable Impulse Propagation through the Zone of Slow Conduction

“…Our findings may support their hypothesis. In contrast, it is well known that the termination of the reentrant VT is responsible for conduction block within the ZSC, as shown in the present case when the PVC were not repetitive (11)(12)(13). Alternation in autonomic activity might contribute to spontaneous changes in the conductivity of the ZSC, leading to initiation of the PVC and VT (14).…”

Localization of the Slow Conduction Zone During Reentrant Ventricular Tachycardia

“…However, ablation will fail if lesions are too small or too far away from the reentry pathway to completely interrupt the circuit. 7 Reentrant tract geometry can be complex and extensive with multiple entrances and exits, 8 so it is sometimes difficult and time consuming, and occasionally impossible, to locate all arrhythmogenic sites. 3,7,8 Entrainment with concealed fusion also occurs by pacing from bystander pathways.…”

“…7 Reentrant tract geometry can be complex and extensive with multiple entrances and exits, 8 so it is sometimes difficult and time consuming, and occasionally impossible, to locate all arrhythmogenic sites. 3,7,8 Entrainment with concealed fusion also occurs by pacing from bystander pathways. 3 At a bystander pathway, activation proceeds from the main circuit loop but is constrained by block lines having the shape of a cul-de-sac; ablation there does not terminate reentry.…”

Sudden Death Prevention With Implantable Devices

“…Prior MI may result in both reduced ejection fraction and abnormalities of conduction and refractoriness that serve as the substrate for ventricular tachyarrhythmias. 24,25 It had been estimated that half of the deaths in the post-MI population are due to VT and VF. 26,27 The relationship between left ventricular systolic dysfunction and deaths due to progressive heart failure and ventricular arrhythmias in patients who have had an MI is well established.…”