Vassil Borislavov Traykov

Ablation of Posteroseptal and Left Posterior Accessory Pathways Guided by Left Atrium–Coronary Sinus Musculature Activation Sequence

Introduction: While some posteroseptal and left posterior accessory pathways (APs) can be ablated on the tricuspid annulus or within the coronary venous system, others require a left‐sided approach. “Fragmented” or double potentials are frequently recorded in the coronary sinus (CS), with a smaller, blunt component from left atrial (LA) myocardium, and a larger, sharp signal from the CS musculature.

Randomized Trial of Intracardiac Echocardiography During Cavotricuspid Isthmus Ablation

Randomized Trial of ICE During CTI Ablation. Introduction: Despite a high success rate, radio‐frequency ablation (RFA) of the cavotricuspid isthmus (CTI) can be unusually challenging in some cases. We postulated that visualization of the CTI with intracardiac echocardiography (ICE) could maximize the succes rate, decrease the procedure and ablation time, and minimize the radiation exposure.

Ventricular location of a part of the right atrial isthmus after tricuspid valve replacement for Ebstein’s anomaly: a challenge for atrial flutter ablation

We report the case of a patient with atrial flutter late after tricuspid valve replacement for Ebstein’s anomaly. Computed tomographic angiography revealed that coronary sinus ostium and part of the right atrial isthmus were located on the ventricular side of the valve ring due to the specific surgical approach in this condition. Based on the results of electroanatomic mapping and entrainment, the arrhythmia was found to be cavotricuspid isthmus dependent clockwise atrial flutter. Completion of the isthmus line required ablation lesions across the artificial valve. When these were delivered the arrhythmia terminated and isthmus block was achieved. Due to arrhythmia recurrence a redo procedure was performed which demonstrated conduction recovery in the ventricular part of the cavotricuspid isthmus. Intracardiac ultrasound-guided ablation successfully eliminated conduction across the isthmus with subsequent freedom from arrhythmia on follow up.

Electrogram analysis at the His bundle region and the proximal coronary sinus as a tool to predict left atrial origin of focal atrial tachycardias

AIMS Early activation at the His bundle (HB) region or proximal coronary sinus (CS) during focal atrial tachycardias (FATs) often necessitates biatrial mapping. Analysis of CS electrograms (EGMs) consisting of a near-field (N) component from CS musculature and a far-field (F) component from left atrial (LA) myocardium can uncover LA activation preceding right atrial (RA) activation. A similar pattern might be observed at the HB. METHODS AND RESULTS Eight patients underwent RA and LA pacing testing the hypothesis that N and F components originating from the RA and LA septum are present in the HB atrial EGM (Pacing group). In this group N preceded F (N-F sequence) in all, while F preceded N (F-N sequence) in seven of eight patients during RA and LA pacing, respectively. Twenty-seven patients with FAT demonstrating earliest activation at the HB or proximal CS during limited RA mapping were also studied (FAT group). Two observers analysed the EGMs at the earliest site during FAT. They found an N-F sequence in 17 (94%) and 16 (89%) of 18 RA FAT and an F-N sequence in seven (78%) and eight (89%) of nine LA FAT, respectively. The F-N sequence predicted the need for LA access with a sensitivity of 78 and 89% and a specificity of 94 and 89%. CONCLUSION Near-field and F components from RA and LA activation can be identified in the HB atrial EGM. Earliest atrial EGM analysis at the HB or CS can predict the need for LA access during FAT ablation.

Converging methods in the assessment of sympathetic baroreflex sensitivity

AIMS Abnormalities of the sympathetic baroreflex regulation are documented in various diseases. The recording of sympathetic nerve activity allows for the calculation of baroreflex gain but this is not available in practice. A non-invasive method based on blood pressure during the late phases of Valsalva manoeuvre (VM) was proposed. Sympathetic gain could be calculated from the pressure fluctuations following ventricular extrasystole or non-sustained ventricular tachycardia (NSVT). METHODS AND RESULTS We assessed both indices in 25 subjects with no significant cardiovascular disease. VM was performed at 40 mmHg for 12 s. Paced NSVT consisted of five to six cycles. The sympathetic gains were determined based on the recovery of mean arterial pressure (MAP, mmHg/s). The maximum slope of five consecutive MAP elevations occurring within a 15-cycle period after NSVT was calculated. This MAP turbulence slope (MAP(TS)) was expressed in mmHg/cycle. Five patients were excluded because of unacceptable VM. VM-derived sympathetic gain (SBRS(vals)) and the NSVT-derived gain (SBRS(NSVT)) correlated closely (R = 0.86, P < 0.001). Their mean difference was 3.2 +/- 4.8 mmHg. Both SBRS(vals) and SBRS(NSVT) correlated closely with MAP(TS) (R = 0.77, P < 0.001 and R = 0.86, P < 0.001, respectively). CONCLUSION The sympathetically mediated arterial pressure recovery is an analogous process following both VM and NSVT. SBRS(NSVT) or MAP(TS) may be useful in the assessment of patients with implanted antiarrhythmic devices.

Tachycardia Triggering Frequent ICD Therapy in a Patient with Dilated Cardiomyopathy—What Is the Mechanism?

Device interrogation during regular follow-up of a 68-year-old male with a single-chamber implantable cardioverter-defibrillator (ICD) and nonischemic dilated cardiomyopathy revealed multiple episodes of sudden onset tachycardia detected in the ventricular tachycardia (VT) zone, always terminated by a single burst of antitachycardia pacing. During these episodes, the near-field and far-field electrograms recorded by the device had a morphology identical to those during sinus rhythm (Fig. 1A). The patient was scheduled for an electrophysiological study, which demonstrated a His-ventricular (HV) interval of 103 ms during sinus rhythm (Fig. 1B). A right bundle branch block (RBBB)like wide QRS tachycardia was reproducibly inducible with atrial programmed stimulation and atrial burst pacing but not with ventricular pacing (Fig. 2A). The QRS morphology during tachycardia was strikingly similar to the one during sinus rhythm and the HV interval was slightly longer. The right bundle was activated retrogradely during tachycardia in contrast to sinus rhythm during which His-bundle activation preceded right-bundle activation (Fig. 2B and C). During spontaneously occurring fluctuations in the tachycardia cycle length changes in His-to-His intervals preceded similar changes in the V-to-V interval (Fig. 3A). Attempts at entraining the tachycardia from the right ventricle repeatedly resulted in its termination. Atrial entrainment is shown in Figure 3B. What can be the mechanism of the tachycardia in this patient?

Supraventricular Tachycardia Inducible Only with Para‐Hisian Pacing—What Is the Mechanism?

A 31-year-old woman with mildly symptomatic, uncorrected Ebstein’s anomaly presenting with ventricular preexcitation and palpitations underwent an electrophysiological study. Nondecremental retrograde ventriculoatrial conduction was demonstrated, and the earliest-retrograde atrial activation was mapped to the posterior tricuspid annulus. Antegradely, there was evidence of progressive, nondecremental ventricular preexcitation with accessory pathway (AP) effective refractory period (ERP) that was shorter than the atrioventricular (AV) node ERP. No tachycardia was inducible with burst pacing and programmed electrical stimulation from the atrium and right ventricular apex. No change in the pattern and timing of retrograde atrial activation upon loss of His bundle (HB) capture was demonstrated by para-Hisian (PHis) pacing, suggesting the presence of retrograde AP conduction (Fig. 1). However, with HB capture, a tachycardia with a cycle length of 420 ms and a right bundle branch, left posterior fascicular block (RBBB + LPFB) pattern and a His-ventricular interval of 56 ms was reproducibly inducible (Fig. 1A). Upon loss of HB capture, no induction occurred (Fig. 1B). During tachycardia, the HB was found to be activated antegradely, confirming supraventricular tachycardia. Ventricular extrastimuli delivered when the HB was refractory reproducibly terminated the tachycardia without being conducted to the atria (Fig. 2). What can be the mechanism explaining the exclusive inducibility by PHis pacing?

A Regular Tachycardia after AV Node Ablation

Figure 1. Regular tachycardia detected as ventricular high rate episode (VHR) by the pacemaker (A). Surface electrocardiogram and intracardiac recordings from the His bundle region (His) and right ventricular apex (RVA) during junctional escape rhythm (B) and induced tachycardia (C). Also shown are H-H and V-V intervals in milliseconds during tachycardia. A 64-year-old woman with idiopathic dilated cardiomyopathy, permanent atrial fibrillation, left bundle branch block (LBBB), and an implanted biventricular pacemaker underwent atrioventricular (AV) node ablation for high ventricular rate and a low percentage of biventricular pacing. A month later, persistent total AV block with an escape rhythm of 45 beats/min was noted during pacemaker interrogation. Several short and one episode

Transition of narrow into wide complex tachycardia with left bundle branch block morphology and varying QRS duration : What is the mechanism?

A 40-year-old male, with preexcitation pattern on the resting electrocardiogram (ECG), paroxysmal palpitations with documented wide complex tachycardia, and no structural heart disease, underwent an electrophysiological study including multipolar recordings from the high right atrium (HRA), coronary sinus (CS), right ventricular apex (RVA), and His bundle (HB) region. The baseline study showed nondecremental ventriculoatrial (VA) conduction. With the above catheter setting, the earliest atrial electrograms during RVA pacing were recorded at the posterior septum with almost simultaneous activation of CS ostium and HRA and later activation at the HB catheter. Mapping of retrograde atrial activation by a roving catheter recorded the earliest atrial signal at the posterolateral tricuspid annulus. Atrial pacing demonstrated progressive antegrade preexcitation with a left bundle branch block (LBBB) pattern. The local electrogram at the right ventricular apex was recorded early with relation to delta wave onset and the right bundle (RB) potential, recorded by the proximal electrode pair of the RVA catheter, preceded the HB activation during maximal preexcitation. The antegrade conduction over the accessory pathway (AP) was decremental with progressive prolongation of stimulus to delta wave interval during programmed atrial stimulation. Upon loss of antegrade AP conduction a narrow QRS tachycardia was induced by programmed atrial stimulation. This was sustained only on isoproterenol infusion. It showed cycle length (CL) alternation between 260 and 290 ms due to alternating atrio-Hissian (AH) interval. The presence of dual atrioventricular (AV) nodal pathways, however, could not be demonstrated throughout the study. The His-ventricular (HV) interval during tachycardia was 53 ms and the atrial activa-