Title: The effectiveness of atrio-ventricular synchronization in single pass lead VDDR pacing over 12-months prospective observation period


INTRODUCTION: VDD/R stimulation is accepted as alternative mode of cardiac pacing to DDD/R in patients with atrio-ventricular conduction block (AVB) and preserved sinus node function. The use of VDD/R pacemakers is rare compared with DDD/R, despite many patients meeting the necessary criteria. The main reason for this is the possibility of inadequate preservation of AV synchronization, which requires effective detection of the atrial signal. So far what determines stable AV synchronization has not been unambigously established, nor has it been determined in which groups of patients this form of treatment should be avoided. THE AIM OF THE STUDY: The aim of the study was to estimate the variability of the detection parameters of the endocavitary atrial signal, and the related effectiveness of AV synchronization over a 12-month prospective observation period. In addition, an attempt has been made to determine the relationship between parameters obtained during assessment the patient for the implantation procedure, using electrocardiographic (ECG) and echocardiographic data, and the effectiveness of AV synchronization. MATERIAL AND METHODS: The study involved a group of 65 patients (43 male - M, 22 female - F), aged 66.6±12.7 with clinically significant disturbances of AV conduction, who did not reveal symptoms of concommitant disturbance in SA node automaticity. Selected ECG and echo parameters were studied prior to the implantation procedure. During the implantation procedure of the VDD/R pacemaker the amplitude (assumed minimum Aav > 1 mV) and stability of atrial potential detection were estimated in relation to breathing condition. The position of the atrial dipole was also determined. Atrial potential parameters were monitored (Aav, Amin, detection threshold) in relation to respiration manoeuvers and body position, over a 12-month follow-up. Follow-up was carried out 3-4 days and 1, 3, 6 and 12 months after the procedure. The effectivenes of AV synchronization (PAS) was estimated by event counter read-out, treadmill exercise and ECG Holter monitoring. RESULTS: The variability of Aav in relation to breathing condition during the procedure was insignificant, except for the Valsalva manoeuvre. In the majority of cases the atrial dipole was localized in the upper part of the right atrium, as shown by optimally stable detection of the A wave potential. The differences in the value of the potential amplitude during respiratory manoeuvres with respect to normal breathing or according to body position were generally statistically insignificant during the whole observation period. Over the 12-month follow-up, the average value of the PAS coefficient was ca. 95% for the entire group of patients. In 74% (group A) synchronization was highly effective (PAS > 95%); in the remaining 26% (group B) PAS occasionally fell below 95%. No statistically significant differences in the atrial potential parameters were found during intra-operative measurements for both groups. A statistically significant correlation between the width of the P wave of the surface ECG and the effectiveness of PAS was clearly demonstrated. In group B, P wave was longer than in group A (105±16 ms vs group A: 94±14 ms; p < 0,005). Similar correlations were found for the echo parameters. The dimensions of the right heart chambers were greater for group B (RVEDD- B: 28.9±5.3 mm vs A: 24.5±4.4 mm; RVESD- B: 22.8±5.4 mm vs A: 19.9±3.8 mm; WGD RA- B: 56.5±6.8 mm vs A: 52.4±5.5 mm; WBP RA- B: 46.4±5.3 mm vs A: 42.7±6.2 mm; RAarea in B: 21.8±3.5 cm2, in A: 18.4±3.3 cm2; RAvol - B: 71.0±21.3 ml, A: 55.5±16 ml), as were those for the left ventricle (LVEDD in B: 59.1±7.4 mm, in A: 54.9±6.0 mm; LVESD w B: 39.9±11.0 mm, A: 35.9±7.9 mm) and the left atrium (WPT LA: in B:46.4±6.2 mm, in A: 42.2±7.7 mm; WGD LA in B: 60.3±9.7 mm, in A: 51.6±9.9 mm; WBP LA for B: 49.0±6.6 mm, and for A: 43.7±12.1 mm). Patients in group B had a lower ejection fraction (49.4±13.7% in B vs 58.2±11. ; 3% in A) and showed symptoms of heart failure. CONCLUSIONS: 1. VDD/R stimulation with a single-pass lead is reliable in achieving effective AV synchronization over a 12-month follow-up. 2. The parameters of the atrial electrogram are stable over a 12-month follow-up and comparable with those obtained during the VDD/R implantation procedure. 3. Detection of the signal from an atrial dipole placed in the upper part of the right atrium is the most stable. 4. The values of atrial amplitude obtained during the procedure, with an established acceptable detection threshold (Aav > 1.0 mV) and maintained stability of detection, are not crucial for atrioventricular synchronization. 5. Selected parameters obtained from ECG and echo examinations are correlated with effective AV synchronization. 6. Enlargement of the right and left heart chambers, reduction of the ejection fraction and congestive heart failure are not conducive to effective AV synchronization in VDD/R pacemakers.

Level of degree:

2 - studia doktoranckie

Degree discipline:

choroby układu krążenia

Degree grantor:

Wydział Lekarski


Jacek Lelakowski

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Biblioteka Medyczna Uniwersytetu Jagiellońskiego - Collegium Medicum

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Last modified:

Feb 12, 2020

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Nov 21, 2012

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Edition name Date
ZB-106441 Feb 12, 2020


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