Cryothermy has potential advantages over RF energy for catheter ablation, including reversibility of lesion formation, catheter stability, and less procedural discomfort. Cryoablation procedures were performed in 14 patients with atrioventricular reentrant tachycardias (AVNRTs), 13 patients with accessory pathway (AP)-mediated tachycardias, and 5 patients with atrial fibrillation. The numbers of energy applications, pain scores, procedural times, and outcomes were recorded and compared with age- and sex-matched patients undergoing similar RF procedures. Cryoablation was successful in 26 of 32 patients (11/14 AVNRT, 10/13 AP, 5/5 AF) compared with 30 of 32 undergoing RF procedures, with similar numbers of energy applications and procedural times. Cryothermy was painless in all patients, and the overall procedural discomfort was significantly less than in patients treated with RF (1.3 +/- 2.2 vs 6.1 +/- 3.5). In patients with anteroseptal pathways, cryomapping successfully identified safe sites to target the delivery of energy. Cryothermy is a painless and safe alternative to RF. It may be particularly useful for catheter ablation of patients with pathways close to the atrioventricular node.

Background: Ripple mapping (RM) is an alternative approach to activation mapping of atrial tachycardia (AT) that avoids electrogram annotation. We tested whether RM is superior to conventional annotation based local activation time (LAT) mapping for AT diagnosis in a randomized and multicenter study. Methods: Patients with AT were randomized to either RM or LAT mapping using the CARTO3v4 CONFIDENSE system. Operators determined the diagnosis using the assigned 3D mapping arm alone, before being permitted a single confirmatory entrainment manuever if needed. A planned ablation lesion set was defined. The primary end point was AT termination with delivery of the planned ablation lesion set. The inability to terminate AT with this first lesion set, the use of more than one entrainment manuever, or the need to crossover to the other mapping arm was defined as failure to achieve the primary end point. Results: One hundred five patients from 7 centers were recruited with 22 patients excluded due to premature AT termination, noninducibility or left atrial appendage thrombus. Eighty-three patients (pts; RM=42, LAT=41) completed mapping and ablation within the 2 groups of similar characteristics (RM versus LAT: prior ablation or cardiac surgery n=35 [83%] versus n=35 [85%], P =0.80). The primary end point occurred in 38/42 pts (90%) in the RM group and 29/41pts (71%) in the LAT group ( P =0.045). This was achieved without any entrainment in 31/42 pts (74%) with RM and 18/41 pts (44%) with LAT ( P =0.01). Of those patients who failed to achieve the primary end point, AT termination was achieved in 9/12 pts (75%) in the LAT group following crossover to RM with entrainment, but 0/4 pts (0%) in the RM group crossing over to LAT mapping with entrainment ( P =0.04). Conclusions: RM is superior to LAT mapping on the CARTO3v4 CONFIDENSE system in guiding ablation to terminate AT with the first lesion set and with reduced entrainment to assist diagnosis. Clinical Trials Registration: https://www.clinicaltrials.gov . Unique identifier: NCT02451995.

To determnine the effects of ventricular preexcitation via accessory atrioventricular connections (ACs) on the sequence of basal ventricular activation, electrophysiologic study records of 22 patients with AC were reviewed. In each, AC site was confirmed by mapping done at operation. Local ventricular preexcitation (VP) timing of local electrograms recorded from these two ventricular sites. In addition to the physiologic insight such information provides, the pattern of local ventricular preexcitation varies with the position of the responsible accessory atrioventricular connection and therefore helps to locate the site of the pathway. Since bundle branch block (BBB) alters the sequence of ventricular activation, we also assessed its confounding effects on indexes of local ventricular preexcitation.

In 1974 and 1975 Brechenmacher presented histological evidence for the existence of atrial fibres bypassing the human atrioventricular node and terminating directly in the His bundle.' 2 He found such direct atrio-His connections in only two of a series of 687 hearts studied histologically. He specifically differentiated the fibres from so-called 'James fibres', which pass from the atrium to the lower atrioventricular node or to the base of the tricuspid valve, and which both he and James consider to be present normally in most, if not all, human hearts.2 The purpose of this paper is to present unusual electrophysiological findings in a single patient which are best explained by an atrio-His fibre of Brechenmacher functioning retrogradely only. Case reportThe patient was a 53-year-old woman who complained of a recurrent sensation of rapid heart action since adolescence which had recently worsened despite medical treatment. Twenty-four hours of ambulatory monitoring showed only two brief runs of supraventricular tachycardia with rates around 170 beats per minute. The Electrophysiological study was undertaken to identify the mechanism of the arrhythmia and to identify an antiarrhythmic regimen which could prevent its recurrence. MethodsThe patient underwent intracardiac electrophysiological study. Quadripolar electrode catheters (interpolar distance = 1 cm) were advanced to the right atrium and the bundle of His position and a hexipolar electrode catheter was positioned at the right ventricular apex and later repositioned in the coronary sinus. Standard recording and stimulating studies were performed, including description of anterograde and retrograde conduction and refractoriness by atrial and ventricular rapid pacing and programmed extrastimulation. Extrastimuli were delivered singly and in pairs during sinus rhythm and at multiple drive rates to the right atrium, coronary sinus, and right ventricle to induce supraventricular tachycardia. Unfortunately, no induced episodes were sufficiently prolonged to permit assessment of the effect of premature atrial or ventricular stimulation upon the tachycardia. INTERPRETATION OF ELECTROPHYSIOLOGICAL RECORDINGSRecordings during spontaneous sinus rhythm were normal. The atrial and right ventricular effective 600