Sinus arrest during radiofrequency ablation from the inferoseptal process of the left ventricle: Proposed mechanisms of an uncommon finding

Figures

• 

  Figure 1. A: A 12-lead electrocardiogram with morphology of premature ventricular contraction (PVC) targeted for ablation. PVC had a left bundle branch block pattern with early precordial transition and an initial isoelectric component in the inferior leads. B: A 6.5-second sinus arrest occurring about 5 seconds after onset of radiofrequency (RF) energy delivery, preceded by an accelerated idioventricular rhythm with a different morphology than that of targeted PVC. C: Prolongation of sinus rate during another RF lesion; atrial pacing immediately upon cessation of ablation showed intact atrioventricular conduction. Vertical bars mark initiation and cessation of RF energy.

• 

  Figure 2. A: Selective left coronary angiography, showing supply of the sinoatrial nodal artery from the proximal left circumflex artery as well left coronary artery to distal right coronary artery collateral flow. B: The heart sectioned and viewed from the right anterior oblique direction. The inferoseptal process is the basal inferomedial part of the left ventricular free wall facing to the septal isthmus anterior to the coronary sinus orifice. Note that the epicardial adipose tissue wedges between the inferoseptal process and coronary sinus orifice. This epicardial adipose tissue potentially contains the efferent/afferent autonomic nerve fibers, ganglionated plexi, and atrioventricular nodal artery. C: Electroanatomic maps showing sites of radiofrequency ablation in the vicinity of the inferoseptal process of the left ventricle.

• 

  Figure 3. Model of control of the heart by cardiac autonomic nervous system. The intrinsic cardiac ganglia system contains sympathetic and parasympathetic efferents, local circuit neurons, and local afferent neurons. Both the intrinsic cardiac ganglia (cardiac ganglionated plexi) and extracardiac intrathoracic ganglia are modulated by the central nervous system. Bezold-Jarisch reflex (BJR) mechanism involves activation of vagal afferent fibers (neurites) whose cell bodies are contained within the nodose ganglia. The central fibers of these neurons ascend in the vagus nerve and enter the brain stem through the solitary tract, and synapse in the medulla. Red arrows show efferent outputs and blue arrows show afferent inputs. Neurite indicates local afferent neurites embedded in the cardiac walls. β1AR = beta 1 adrenergic receptor; DRG = dorsal root ganglion; GP = ganglionated plexi; M2 = muscarinic acetylcholine receptor type 2; Figure adapted from Fedele and Brand.9