Diastolic atrio-ventricular (AV) regurgitation is a well-known phenomenon in patients with high-degree AV-block. A negative AV pressure-gradient following atrial relaxation causes a late-diastolic AV regurgitation. For the first time, we were able to describe a similar phenomenon, notably, during mid-diastole, in a highly-trained 25-year-old triathlete (total amount of training 15-20 hours per week, divided up into approximately 10km swimming, 200km cycling and 50km running per week).
Observations: Diastolic tricuspid regurgitation (DTR) occurred between passive early diastolic (E-wave) and active late diastolic (A-wave) ventricular filling (Panel 1A-B). The extent of regurgitation was depending on intrathoracic pressure as it increased during expiration and Valsalva manoeuver. Diastolic regurgitation was only observed over tricuspid valve - in contrast to mitral valve (Panel 1D).
Pathophysiology: We postulate that there exist two crucial mechanisms. First, sinus bradycardia with prolonged duration of diastole with sufficient time in between E- and A-wave (Panel 1B). Second, an enlarged, highly compliant right ventricle allowing a transfer of intrathoracic respiratory pressure variations to the heart. Notably, DTR correlates to hepatic vein flow variation. Hepatic diastolic flow reversal is pronounced during expiration and decreased during inspiration (Panel 1C). The lack of a corresponding diastolic mitral regurgitation might be explained by the minimally higher pressure within the left atrium compared to the right atrium (approximately 8 vs. 3 mmHg) making it less prone to a negative AV-gradient due to respiratory pressure changes.
Conclusion: Diastolic tricuspid regurgitation seems to be a rather physiological than pathological phenomenon in highly-trained endurance athletes due to distinct sports adaptations of the heart and its surrounding structures.
Caption Figure 1:
Panel A. 3D-Color-Doppler-video still of tricuspid valve region (zoom); long arrow marks mid-diastolic regurgitation.
Panel B. Color M-mode over tricuspid valve; short arrow marks mid-diastolic tricuspid regurgitation.
Panel C. Hepatic vein flow. * Inspiration, ** expiration, *** diastolic flow reversal.
Panel D. Color M-mode over mitral valve. No diastolic regurgitation.
https://www.abstractserver.com/dgk2019/ht/abstracts//P322.htm