[Long-term clinical assessment of single-lead VDD electric stimulation]. / Valutazione clinica a lungo termine dell'elettrostimolazione VDD monocatetere.

BACKGROUND: During the last decade single lead VDD pacing has been progressively affirmed as an electrotherapy of choice in patients with advanced atrioventricular block without alterations of the sinus function. It combines the benefits of P-synchronous ventricular pacing with an easy implant procedure when compared to the conventional DDD approach. The aim of this study was to evaluate the validity of such an approach in a large population of patients, all implanted in a single center. METHODS: From 1987 up to now, 317 patients, all affected by advanced atrioventricular block and without sinus node dysfunction, were implanted in our center with a single lead VDD pacemaker. During follow-up the persistence of a proper atrioventricular synchronization was assessed and evaluated. RESULTS: The mean follow-up was 3.9 +/- 2.7 years/patient (range 6-138 months). The 94.6% of implanted systems maintained the normal VDD pacing function. Permanent reprogramming in VVI mode was necessary in 17 patients (5.36%); in 12 (3.78%) because of chronic atrial fibrillation and in 5 (1.63%) for loss of atrial sensing. The percentage of atrial synchronization was optimal (> 98%) and acceptable (> 95%) in 81% and 19% of patients, respectively. Episodes of paroxysmal atrial fibrillation occurred in 3 patients. Neither inhibition by myopotentials nor occurrence of sinus node disease was observed during follow-up. These results are in accordance with those reported by previous studies, performed on a smaller population or on a multicenter basis, and are comparable with the results reported for conventional DDD pacemaker. CONCLUSIONS: Our results confirm the high reliability of the single lead VDD pacing system concerning the long-term persistence of a proper atrioventricular synchronization. Data showed above enforce our opinion that this pacing approach should be considered the treatment of choice in patients with advanced atrioventricular block and preserved sinus node function.

Doppler echocardiographic assessment of left ventricular isovolemic relaxation flow.

BACKGROUND: It is not infrequent to observe a peculiar intraventricular relaxation flow (IRF) pattern during the isovolumic relaxation time (IRT), especially in patients (pts) with left ventricular hypertrophy (LVH). This is even more likely in pts with hypertrophic obstructive cardiomyopathy and in VVI-paced pts. Despite these observations, the prevalence and clinical relevance of this finding have not been evaluated thoroughly and systematically in a consecutive series of patients. METHODS: Ninety-two consecutive pts underwent a conventional Doppler echo study for the evaluation of systolic and diastolic function (fractional shortening, EF, E and A wave velocity, duration and ratio, and IRT). of these, 42 pts had LVH, 14 had mitral regurgitation (MR) with depressed EF, 8 had CAD with depressed EF and 28 were normal subjects. IF was searched for during the evaluation of IRT and its duration, velocity and integral were measured when noted. RESULTS: Fifty-six patients (61%) showed an IRF at Doppler examination. Of these, fifteen were normal subjects (53%) and 34 (81%, p = 0.03 vs normal) were hypertensive pts. Among pts with depressed EF, only two of 14 with MR and 5 of 8 with no MR showed an IRF (14 vs 62%; p = 0.032). When evaluating LV function, we observed that pts with an IRF had a larger atrial filling fraction, a longer isovolumic relaxation time and a higher ejection fraction with respect to pts with no IRF (respectively, 40 +/- 13% vs 30 +/- 13%, p = 0.005; 108 +/- 23 ms vs 77 +/- 22 ms, p = 0.0001; 70 +/- 14% vs 61 +/- 16%, p = 0.01). CONCLUSIONS: Our data confirm that IRF may be observed in healthy subjects and may be due to an asynchronous relaxation of the LV during IRT, in consideration of a higher prevalence of a greater atrial filling fraction in pts with IF as compared to those in whom this Doppler signal is absent. Moreover, IRF is more frequent in pts with LVH and is rare in pts with MR (predominantly due to a very short isovolumic relaxation time).