Purpose .– To analyse the relationship between changes in the transvalvular impedance signal (TVI) and echocardiographic markers of cardiac hemodynamics, during physical stress.

Methods .– A semi-supine self-limited exercise echocardiography was performed in eight consecutive patients (mean age: 72 ± 8 years, three males) implanted for standard indications with a dual-chamber pacemaker equipped with the TVI sensor (Sophòs 155). Left ventricular (LV) volumes were measured using the biplane Simpson method. Pulsed-wave Doppler and Tissue Doppler Imaging were used to quantify mitral E wave and mitral annulus Ea wave respectively. At rest and exercise, E/Ea ratio was used to assess the LV filling pressure. Concomitantly, the TVI waveform was derived and processed by the implanted pacemaker. TVI increases in systole and decreases in diastole, suggesting an inverse relationship with the ventricular volume.

Results .– At peak exercise, sinus rate and aortic VTI were increased, respectively, by 31 ± 13 bpm and 16 ± 12% versus the resting levels. The enhanced LV stroke volume was mainly the result of an increased LV end-diastolic volume (EDV: +17 ± 13 ml), while the LV end-systolic volume showed not significant changes (+2 ± 10 mL). The preload increase under stress was further confirmed by the increased peak velocity of mitral E-wave (+50 ± 55%). During stress, E/Ea ratio decreased in five patients and increased in the remaining. Physical exercise induced an increase in the peak-peak amplitude of the TVI waveform, concomitantly to a decrease in E/Ea ratio. In contrast, the TVI signal amplitude was decreased in patients with increased E/Ea. The stress-induced changes in TVI wave and E/Ea ratio were well correlated (R2 = 0.76). The end-diastolic TVI was reduced during exercise in all patients, and its relative modification was inversely correlated with the relative change in LVEDV (R2 = 0.73).

Conclusion .– The TVI waveform is sensitive to LV diastolic volume and filling pressure, as assessed by transthoracic echocardiography.