Idiopathic Ventricular Arrhythmia Originating From the Cardiac Crux or Inferior Septum

Abstract

Background-Idiopathic ventricular arrhythmia (VA) can arise from the epicardium near the posteroseptal region (cardiac crux). There are only 2 prior reports describing idiopathic VA from the cardiac crux. The purpose of this study was to characterize the clinical and the electrocardiographic features of idiopathic crux VA. Methods and Results-Crux VA was identified in 18 patients undergoing catheter ablation. We divided patients into 2 groups, those with VA originating from the apical crux (n=9) and the basal crux (n=9). We described the clinical and electrocardiographic characteristics of crux VA as well as the ablation results. Furthermore, we compared clinical features of crux VA with other sites of idiopathic VA. Fifteen crux VA patients (83%) had sustained ventricular tachycardia and 3 patients required implantable cardioverter defibrillator implantation because of syncope. All patients had a left superior axis and 16 patients had R>S wave in V2. In apical crux VA, all patients had a deep S wave in V6 and 8 patients (89%) had R>S wave in aVR. All apical crux patients underwent attempted ablation in the middle cardiac vein without success. In 4 of these patients, epicardial ablation with subxiphoid approach was performed successfully. All basal crux VA patients had either negative or isoelectric pattern in V1 and had R>S in V6. Patients had successful ablation within the middle cardiac vein. Conclusions-Apical versus basal crux VA is identified as a new category of idiopathic VA with distinctive electrocardiographic characteristics; ablation via the middle cardiac vein is effective for eliminating basal crux VA, whereas apical crux VA often requires a subxiphoid epicardial approach. (Circ Arrhythm Electrophysiol. 2014;7:1152-1158.)

Mechanism, diagnosis, and treatment of outflow tract tachycardia

“…62 The basal crux is accessed through the proximal middle cardiac vein from the coronary sinus. Ablation can be successfully performed from either the proximal coronary sinus or middle cardiac vein (≤2 cm from its ostium).…”

“…Arrhythmias originating from the cardiac crux account for approximately 2% of idiopathic VT referred for ablation. 62 VT is distributed evenly between the basal and apical sites, but basal VT is more often associated with syncope than apical VT. Characteristic electrocardiographic findings for basal crux VT include a superior axis with a QS pattern in lead III and a left bundle branch block morphology with an early transition in lead V 2 (Figure 6b).…”

“…Characteristic electrocardiographic findings for basal crux VT include a superior axis with a QS pattern in lead III and a left bundle branch block morphology with an early transition in lead V 2 (Figure 6b). 62,63 Apical crux VT also has a superior frontal plane axis, but can present with a right bundle branch or left bundle branch block pattern. The presence of an R:S ratio <1 in lead V 6 has 100% sensitivity and specificity for apical VT, as well as a 100% positive and negative predictive value.…”

Idiopathic basal crux ventricular arrhythmias with left bundle branch block and superior axis: A comparison with inferior‐septal valvular arrhythmias

“…VA originating from the basal location was recognized by a superior axis with LBBB pattern compared to those with an apical location, which shows right bundle branch block (RBBB) or/and LBBB pattern …”

Electrocardiographic landmarks of idiopathic ventricular arrhythmia origins

“…It has been divided schematically to basal and apical crux. The basal crux lies within the proximal 2 cm of the middle cardiac vein and is accessible endocardially via the ostium of the middle cardiac vein 38. The apical crux is located more distally within the middle cardiac vein and epicardially compared with the basal crux and the access can be attempted via a percutaneous subxiphoid approach.…”