Acute effects of right ventricular pacing on cardiac haemodynamics and transvalvular impedance

Abstract

Aims.To assess the acute side-effects of right ventricular (RV) stimulation applied in apex and mid-septum, in order to establish the optimal lead location in clinical practice. Methods. During pacemaker implantation, the ventricular lead was temporarily fixed in the apex and then moved to mid-septum. In both positions, surface and endocardial electrograms and transvalvular impedance (32 cases), left ventricular (LV) pressure (23), and transthoracic echocardiography (10) were acquired with intrinsic activity and VDD pacing. Results. A larger increase in QRS duration was noticed with apical than septal pacing (65 ± 25 vs. 45 ± 29 ms; P<10 -4 ). The proportion of cases where RV stimulation affected the transvalvular impedance waveform was higher with apical lead location (56% vs. 20%; P<0.02). VDD pacing at either site reduced the maximum dP/dt by 6% with respect to intrinsic AV conduction (IAVC; P<0.005). The maximum pressure drop taking place in 100 ms was reduced by 6 and 8%, respectively, with apical and septal pacing (P<0.01 vs. IAVC). Apical VDD decreased mitral annulus velocity in early diastole (E') from 7.5 ± 1.4 to 5.9 ± 0.9 cm/s (P<0.02) and prolonged the E-wave deceleration time (DT) from 156 ± 33 to 199 ± 54 ms (P<0.02), while septal pacing induced non-significant modifications in E' and DT. Conclusion. Ventricular stimulation acutely impairs LV systolic and diastolic performance, independent of the pacing site. Septal lead location preserves RV contraction mechanics and reduces the electrical interventricular delay.

Hemodynamic Surveillance of Ventricular Pacing Effectiveness with the Transvalvular Impedance Sensor

“…With this pacing mode, the TVI waveform recorded with the tip ventricular electrode often showed an early and steep rise, which made difficult the measurement of the minimum presystolic value. Since TVI is modulated by cross-section changes occurring in the ventricular region where the recording electrode is placed [ 17 , 18 ], which was the right apex in the present experience, we could speculate that the movement of the stimulated ventricular myocardium is delayed by the active blood inflow, especially if the AV delay is short, or by passive stretching of the ventricular wall which might be caused by the atrial contraction. For all these reasons, the use of TVI for capture verification during VVI pacing was possible in 85% of the cases.…”

“…In conditions of ventricular pacing as well, TVI looks best suited to a function of ejection confirmation aimed at increasing the reliability of the pacing system, rather than to the continuous measurement of the pacing threshold required for the fine regulation of pulse energy [ 4 , 12 ]. Indeed, the TVI fluctuation follows the time-course of ventricular contraction and relaxation and is therefore a slow signal, which must be sampled for some hundreds of milliseconds to state whether the ejection is taking place or not [ 15 , 17 , 18 ]. In case of a negative result, the diagnosis is available too late to deliver a high energy back-up pulse within the current cardiac cycle.…”

“…In this aim, the measurement of cardiac impedance in transvalvular configuration (TVI) has been proposed as a tool for timely ejection recognition after either ventricular sensing or pacing [ 14 ]. TVI is derived throughout the cardiac cycle and increases when ejection occurs, decreasing back to the diastolic value as a result of ventricular filling [ 15 – 18 ]. Thanks to a very high signal to noise ratio, the systolic TVI rise can be used as a sensitive ejection marker.…”

Rate-Responsive Cardiac Pacing: Technological Solutions and Their Applications

“…Changes in the TVI waveform correspond to echocardiographic recordings of filling parameters used in the evaluation of myocardial contractility under the influence of right ventricular stimulation. This allows for an indirect assessment of changes in ventricular contractility with stimulation from the septal region compared to the apical region of the right ventricle [ 119 ]. Diagnostic information on trends in TVI, due to reliable correlation with hemodynamic parameters in preclinical studies, may prove valuable in cardiac disease therapy in patients with an implanted device [ 120 ].…”