Electrocardiographic Parameters as Predictors of Response to Cardiac Resynchronization Therapy.

INTRODUCTION: Although strict selection criteria are used to select patients for cardiac resynchronisation therapy, up to 30% of patients do not have a positive clinical response. PATIENTS: A total of 102 consecutive patients who had biventricular pacemaker/defibrillator (CRT-P or CRT-D) implanted were enrolled in this prospective observational study. RESULTS: During the average follow-up period of 24.3 months 5 patients died and 17 (16.7%) patients were hospitalised with the symptoms of heart failure; 75 (73.5%) patients were responders based on the previously defined criteria. Responders in the group of LBBB patients kept the significant difference in a computed variable (S1 + R6) - (S6 + R1) and R6/S6 ratio. Responders in non-LBBB patients kept the significant difference only in the height of R waves in V6. The R6/S6 ratio tended to be higher, but it did not reach a statistical significance. CONCLUSION: None of the tested ECG parameters stands out as an independent predictor of response to cardiac resynchronisation therapy, but some of them were different in responder-compared to the non-responder group. The amplitude of R wave in V6, higher R/S ratio in V6 and higher computed variable (S1 + R6) - (S6 + R1) may predict the likelihood of response to CRT therapy in both LBBB-patients and non-LBBB patients.

Scoring System Assessment of Cephalic Vein Access for Device Implantation.

The purpose of this study was to explore the usability of the cephalic vein (CV) for cardiac implantable electronic device (CIED) lead access by applying a scoring system to assess the venous anatomy. This prospective, single-center study included 100 consecutive patients who underwent CIED implantation within a period of one year. Contrast-enhanced venography images were obtained for every patient, focused on the CV, "T-junction," and the subclavian/axillary veins (SV/AVs). Though careful examination of the images, an angle, valves, diameter, noncollateral (AVDnC) score was constructed and used to aid in choosing a CV or SV/AV access approach; in all cases, however, the preferred approach was CV independent of the AVDnC score result obtained. Upon use of the scoring system, the majority of patients (54%) had type A score result (≥ 3), indicating a favorable anatomy for CV access. In 48 of these patients, the CV was used for the implantation of at least one lead. The remaining 46 (46%) patients had type B score result (≤ 2). In 41 patients from this group, SV/AV access was used for lead implantation and, in five patients, CV access was used. The number of leads introduced through the CV was associated with larger score and the operator's experience. In conclusion, in more than 50% of patients, at least one lead could be introduced through the CV. The scoring system used herein can simplify the choice between CV and SV/AV access and could eventually increase the efficiency and safety of the procedure, especially when less experienced implanters are involved.

Anticoagulation Management in Patients with Pacemaker-Detected Atrial Fibrillation.

INTRODUCTION: In patients with an implanted pacemaker, asymptomatic atrial fibrillation (AF) is associated with an increased risk of thrombo-embolic complications. There is still no consensus which duration of episodes of atrial fibrillation should be taken as an indicator for inclusion of oral anticoagulation therapy (OAC). MATERIAL AND METHODS: A total of 104 patients who had no AF episodes in the past and have an indication for permanent pacing were included in the study. RESULTS: During an average follow-up of 18 months, 33 of the patients developed episodes of AF. Inclusion of OAC was performed in 17 patients, in whom AF was recorded, although in all patients CHA2DS2-VASc score was ≥ 1. The inclusion of OAC showed a statistically significant correlation with increasing duration of episodes of AF (r = 0.502, p = 0.003). During the follow-up period none of the patients developed thrombo-embolic complication. CONCLUSION: Considering that our group of patients had no thrombo-embolic events, we could conclude that dividing the AF episodes in less than 1% in 24 hours and longer than 1% within 24 hours could be an indicator for decision-making to include OAK if the CHA2DS2-VASc score is ≥ 1.

Pulse amplitude adjustment provides immediate pacemaker longevity gain.

OBJECTIVE: Adjusting pacemaker pulse amplitude influences the longevity of the pacemaker. Our aim was to establish the initial longevity gain. METHODS: Forty randomly selected patients with implanted pacemakers were analyzed. Mean age was 65.58+/-13.7 years. All pacemakers were working on factory settings of pulse amplitude 3.5 V and pulse width of 0.4 ms for average of 3 years before the adjustment. Initial mean longevity was projected to 68.61+/-18.86 months, mean battery voltage 2.78 V, and mean battery current 14.21+/-2.61 microA. RESULTS: Pulse amplitude threshold test was performed and average value of 0.632+/-0.22 V was obtained. Pulse amplitude was programmed to 2.5 V and pulse width was left unchanged. New readings of battery data were obtained. Battery voltage did not show immediate changes, and battery current decreased to 11.53+/-1.98 microA. New average longevity was projected to 81.03+/-19.82 months, which presents a 12.42 months of initial longevity gain with statistical significance at 95% confidence interval (p=0.003). Positive correlation was found between the new pulse amplitude and new values of battery current (p<0.01). CONCLUSION: Pulse amplitude decrease of only 1 V provides significant initial longevity gain of more than a year. If found correlations would have any impact on further longevity gains over longer period of time is yet to be established.

Induction of atrioventricular node reentry by simultaneous anterograde conduction over the fast and slow pathways.

Atrio-ventricular node reentry (AVNRT) is typically induced with an anterograde block over the fast pathway (FP) and conduction over the slow pathway (SP), with subsequent retrograde conduction over the FP. Rarely, a premature atrial complex (PAC) conducts simultaneously over the FP and SP to induce AVNRT. Previous publications have reported that conduction over the fast and slow pathway of the atrioventricular node can occur successively one after the other, thus leading to dual ventricular depolarization from what initially was a single atrial impulse. We report a case of an 18-year-old male patient referred for repeated bursts of ectopic activity. Evaluation of the patient's electrocardiographic recordings suggested the presence of dual ventricular activations for each atrial beat. The electrophysiological study revealed that the patient had simultaneous conduction over the fast and slow pathways of the atrioventricular node giving rise to a non-reentrant tachycardia, along with an absence of retrograde (ventriculoatrial) conduction, and a significant atrio-His bundle jump (A-H jump) through the slow pathway from the fast pathway during programmed electrical stimulation from the right atrium. Ablation of the slow pathway at the base of the Koch triangle yielded a cessation of the dual ventricular response, absence of the nonreentrant tachycardia and no A-H jump.