Direct His Bundle Pacing Post AVN Ablation

Atrioventricular nodal (AVN) ablation with concomitant pacemaker implantation is one of the strategies that reduce symptoms in patients with atrial fibrillation (AF). However, the long-term adverse effects of right ventricular (RV) apical pacing have led to the search for alternating sites of pacing. Biventricular pacing produces a significant improvement in functional capacity over RV pacing in patients undergoing AVN ablation. Another alternative site for pacing is direct His bundle to reduce the adverse outcome of RV pacing. Here, we present a case of direct His bundle pacing using steerable lead delivery system in a patient with symptomatic paroxysmal AF with concurrent AVN ablation.     

Utilization of Permanent His‐Bundle Pacing for Management of Proarrhythmia Related to Biventricular Pacing

Biventricular pacing has occasionally been associated with ventricular proarrhythmia, which at times can be refractory to conventional antiarrhythmic drug therapy and ablative intervention. Recently, permanent His‐bundle pacing has emerged as a reasonable alternative to right ventricular and biventricular pacing. In addition, by maintaining the physiologic pattern of ventricular electrical activation, it is less likely to be arrhythmogenic. We report the use of permanent His‐bundle pacing to manage ventricular proarrhythmia that developed after initiation of biventricular pacing and was unresponsive to antiarrhythmic and ablative therapy.     

Utility of High‐Output His Pacing during Difficult AV Node Ablation. An Underutilized Strategy

Atrioventricular (AV) node ablation is a commonly performed procedure for patients with chronic drug refractory atrial fibrillation (AF) with episodes of rapid ventricular response. We report on a 72‐year‐old man who had difficulty managing chronic drug refractory AFs with frequent hospitalizations for rapid ventricular rate. The patient was taken to the electrophysiology laboratory for AV node ablation. Extensive mapping and localization techniques of the compact AV node and ablation in the region were unsuccessful. Subsequently, high‐output His bundle pacing using 20 mA at 2 ms of output energy was performed in an attempt to localize the His bundle in areas where high‐output pacing resulted in a narrower QRS complex. Further ablations in the areas where pacing produced a narrower QRS complex resulted in complete heart block. This case highlights the importance of using this simple pacing maneuver to achieve complete heart block in patients in whom standard strategies to localize and ablate the compact AV node are unsuccessful.     

Radiofrequency Catheter Atrioventricular Node Ablation in Patients with Permanent Cardiac Pacing Systems

Following successful BF ablation of the atrioventricular node (AVN), temporary pacing is necessary prior to insertion of a permanent pacemaker. The risks and inconvenience of temporary pacing could be avoided if a permanent pacemaker is already in place. This study reports the feasibility of RF ablation of the AVN in 27 patients (age 55 ± 17 years, 15 males) with hypertrophic cardiomyopathy and pacemakers, Indications for AVN ablation were drug refractory atrial fibrillation in 24 patients, and rapid AVN conduction preventing septal pre-excitation by DDD pacemaker, inserted for relief of left ventricular outflow obstruction, in three cases. Sixteen patients had DDD devices and 11 patients had VVI devices. During RF ablation, each pacemaker was programmed to VVI at 50 beats/min. The ablation catheter was manipulated with fluoroscopic control to avoid close contact with or disturbance of the pacing leads. In 16 patients, RF ablation was performed immediately following pacemaker implantation but in the remaining patients, the AVN was ablated 6–32 months after pacemaker implantation. The power applied was 25–50 watts for a duration of 15–60 seconds. AV block was achieved in all cases but required 34 ± 36 applications for 16.5 ± 17.8 min/case. RF ablation consistently caused reversion to magnet rate in one patient and temporarily inhibited appropriate pacemaker discharge in another. However, no other pacemaker or lead malfunction was detected so that temporary pacing was not required in any case. At 6 ± 3 months follow-up, all pacemakers were functioning normally without alteration in pacing parameters from baseline. Thus. RF ablation of the AVN can be performed safely in the presence of a recently implanted permanent pacemaker, without temporary pacing.     

Long-Term Follow-Up of Patients Treated By Radiofrequency Ablation of the Atrioventricular Junction

JENSEN, S.M., et al .: Long-Term Follow-Up of Patients Treated By Radiofrequency Ablation of the Atrioventricular Junction . Radiofrequency ablation of the AV conduction tissue (His-bundle ablation) is an accepted treatment for therapy resistant atrial fibrillation/flutter. However, data on the long-term effects of the procedure are limited. We followed 50 patients for a mean of 17 months after AV junction ablation. The indication was treatment resistant atrial fibrillation or flutter. The patients underwent a standardized interview performed by two nurses. Health care was studied via the in-patient register. Subjective improvement was reported by 88% and the number of days in hospital per year was reduced from 17 to 7. The use of antiarrhythmic drugs was reduced by 75%. If the reduction in costs of drugs and days in hospital is compared with the cost of the ablation and the pacemaker implantation, breaking even is achieved after 2.6 years. We could not confirm that patients with paroxysmal atrial fibrillation note less improvement than those with chronic fibrillation. Conclusion: Ablation of the AV junction is a cost effective treatment with good long-term results and relatively few complications. Recommendations: Chronic atrial fibrillation: If sinus rhythm cannot be established and in cases in which heart rate regulating drugs have been ineffective, ablation of the AV junction with implantation of a VVIR pacemaker is recommended. Paroxysmal atrial fibrillation: If the patient despite treatment with antiarrhythmic drugs continues to have symptomatic episodes of atrial fibrillation, then AV junction ablation with implantation of a permanent pacemaker is recommended. Patients who have self-limiting episodes of atrial fibrillation should be given a DDDR pacemaker with an automatic mode switch. Patients who do not have self-limiting attacks and require DC conversion, should receive a VVIR pacemaker     

Physiology of the Escape Rhythm After Radiofrequency Atrioventricular Junctional Ablation

The physiology of the escape rhythm (ER) and its response to pharmacological modulation under varying autonomic conditions were studied in 48 patients undergoing radiofrequency ablation of the atrioventricular junction (AVJ) for refractory atrial fibrillation. The QRS morphology and cycle length (CL) of the baseline ER were measured 15 minutes postablation. The CL of the ER was measured in response to doses of isoproterenol, atropine, adenosine, lidocaine, and verapamil. The ER QRS was narrow (QRS < 120 ms) in 20 patients and wide (QRS > 120 ms) in 28 patients. Of the 28 patients with wide QRS ER, 11 patients had a new bundle branch block (8 patients new right bundle branch block [RBBB] and 2 patients new left bundle branch block [LBBB]). The ERCL was similar in both narrow and wide ERs (1,593 ± 376 ms and 1,516 ± 296 ms, P = 0.44). In 23 patients receiving isoproterenol infusion, the ER CL decreased with increasing doses from 1 mcg/min to 2 mcg/min (1,378 ± 200 to 1,240 ± 229 ms, P < 0.001), but did not decrease further at 3 mcg/min [1,201 ±192 ms, P = 0.48 vs 2 mg/min). Seven patients received 0.02 mg/kg of atropine, and ER decreased significantly (1,572 ± 408 ms to 1,319 ± 333 ms, P = 0.028). In 30 patients who received intravenous boluses of adenosine (6–18 mg), the ER did not change significantly. In 28 patients who received 150 mg of lidocaine, the ER increased from 1,462 ± 286 ms to 1,715 ± 467 ms (P < 0.001), and one patient developed transient asystole. Nineteen patients received 7.5 mg of verapamil, and the ER did not change (1,488 ± 313 ms to 1,513 ± 666 ms, P = 0.80). There was no significant difference in response to isoproterenol, adenosine, lidocaine, or verapamil between the patients with wide and narrow QRS ERs. We conclude that patients may have stable ERs immediately following AVJ ablation even when a wide complex ER results. The ER is responsive to sympathetic stimulation and vagal blockade. The ER is prolonged after lidocaine but not after verapamil, suggesting response to sodium but not to calcium channel blockade. These data are consistent with an ER originating in the distal compact AV node or proximal His bundle.     

Ablating the Imperceptible: A Novel Application of Para‐Hisian Pacing

In some elderly patients with atrial fibrillation, especially in combination with heart failure, a rate control strategy may be preferred. When pharmacological therapy is ineffective or not tolerated, it is reasonable to perform atrioventricular (AV) node ablation with ventricular pacing. We describe a case in which this approach was necessary for management. However, the presence of periprocedural, drug‐induced AV block just before ablation provided a unique and challenging circumstance. We discuss the steps taken to ensure a successful procedure.     

Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single Site and Biatrial Pacing

It has been reported that a trial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS-d), or biatrial (simultaneous BAA and CS-d) pacing. In the AF group, AF inducibility was significantly higher with BAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS-d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS-d paced drive. The atrial recovery time (ART) at RAA and CS-d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS-d was calculated as the ART difference (ARTD). The ARTD was significantly longer during BAA pacing in the AF group than in control group (155.0 +/- 32.8 vs 128.8 +/- 32.9 ms, P < 0.05). In the AFgroup, ARTDs during biatrial (52.0 +/- 24.2 ms) and CS-d pacing (51.7 +/- 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS-d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS-d and biatrial pacing significantly reduced ARTD compared with RAA pacing.     

Dual Chamber Pacing in Hypertrophic Obstructive Cardiomyopathy: Beneficial Effect of Atrioventricular Junction Ablation for Optimal Left Ventricular Capture and Filling

Clinical improvement with dual chamber pacing bas largely been reported in patients suffering from hypertrophic obstructive cardiomyopathy and mainly attributed to the reduction of the subaortic pressure gradient. To be effective, pacing must induce a permanent and complete capture of the LV. In two patients of our collective, symptoms (angina and dyspnea NYHA Class III and/or syncopes) persisted or relapsed despite pacing. This was related to the inability to obtain full LV capture due to a too-short native PR interval. RF ablation of the AV junction was therefore performed in botb patients, resulting in permanent AV block in one and prolonged PR interval up to 310 ms in the second. Pacing was thereafter associated with an immediate and significant clinical improvement related to permanent LV capture, whatever the patient's activity. After RF ablation, the AV delay was set up to induce the best LV filling, as assessed by Doppler analysis of mitral flow. Our observations suggest that RF ablation or modification of the AV junction can be a successful procedure in some patients with residual or recurrent symptoms, when the latter result from a loss of capture or from the inability to program an AV delay tbat does not compromise the active component to LV filling. Doppler echocardiography is a simple and effective mean to assess the hemodynamic effect of AV interval modulation in this setting.     

A Strategy to Achieve CRT Response in Permanent Atrial Fibrillation without Obligatory Atrioventricular Node Ablation

Background: Cardiac resynchronization therapy (CRT) is an established method in patients with severe heart failure and wide QRS configuration, particularly during sinus rhythm (SR). In CRT patients with permanent atrial fibrillation (AF), there is no general consensus regarding the need for atrioventricular node (AVN) ablation. The aim of this study was to evaluate the benefit of CRT in permanent AF with and without AVN ablation. Methods: New York Heart Association classification, QRS duration, and echocardiographic parameters were assessed before and after CRT with a follow-up of 12 ± 3 months. Two hundred thirty patients in SR and 46 patients with permanent AF of 2.1 ± 0.5 years duration were studied. AVN ablation was performed only in AF patients with insufficient pharmacological rate control evidenced by ≤80 % ventricular stimulation. Results: Fifteen AF patients underwent AVN ablation. Biventricular pacing comparably improved functional status, left ventricular ejection fraction, and left ventricular end-diastolic dimensions in all treated groups. Biventricular stimulation percentage was 10% lower in pharmacologically treated AF patients over 1 year as compared to patients in SR and to AF patients undergoing AVN ablation, which did not affect outcome in this patient population. Conclusion: In patients with permanent AF and CRT, an AVN ablation strategy might not be strictly required in all patients. (PACE 2012; 35:943-947).     

Determination of the Left Bundle Branch Refractoriness by Distal His Bundle Pacing in Patients with Left Bundle Branch Block

Electrophysiological studies were carried out in two patients with an idiopathic leff bundle branch block. Consisfenl distal His bundle pacing resulted in the normalization of the QRS complex in both pa lien ts. Extrastimulation during basic distal His pacing at several cycle lengths was carried out successfully. Using this technique, the refractory periods of the left bundle branches were measured and found to be within the normal range. In addition, they decreased with the shortening of the basic cycle length. These results demonstrated the possibility of determining the refractoriness of the left bundle branch by His bundle pacing in patients with left bundle branch block. Hypotheses are postulated about the presumed location of the lesion responsible for the left bundle branch block.     

Identifying Patients for Rate Responsive Atrial Pacing: A New Method for Patient Selection and Pacemaker Programming

In patients with sinus node disease (SND) and chronotropic incompetence, atrial rate adaptive stimulation (AAI, R pacing) is regarded as the most appropriate pacing mode. Since coronary artery disease is the most common etiology in these patients, we evaluated a new technique combining two-dimensional transesophageal echocardiography and atrial transesophageal pacing to detect pacing induced wall motion abnormalities and assess safe upper rate limits. Thirty-five patients were studied; 26 with and 9 without angiographic coronary artery disease. Stable atrial capture was achieved in all patients using 12 ± 3 msec pulse width and 12 ± 4 mA current strength. Sensitivity and specificity for the detection of coronary artery disease was highest for transesophageal echocardiography during pacing (sensitivity 81%, specificity 100%). Simultaneous 12-lead ECG during pacing had lower values (sensitivity 57%, specificity 75%). Pacing induced wall motion abnormalities preceded ST segment changes in all patients. Exercise stress testing showed similar values (sensitivity 62%, specificity 89%), It is concluded that simultaneous transesophageal echocardiography and transesophageal pacing is a safe and useful technique in selecting patients for AAI, R pacing and for the detection of safe upper rate limits, particularly when coronary artery disease is suspected.