ABSTRACT
BACKGROUND AND AIM OF THE STUDY: The results of previous studies have suggested that an increase in heart rate (HR) may have a beneficial effect on the hemodynamic condition of patients with aortic regurgitation (AR), and reduce AR severity. An increase in HR was shown to cause a significant increase in regurgitant slope and to significantly shorten the pressure half-time (PHT), both of which are considered to be signs of worsening regurgitation. Color M-mode Doppler flow propagation velocity (FPV) was used to assess AR severity, but no data were available regarding the effects of HR on FPV measurement of AR. The study aim was to evaluate the effect of HR on FPV, and to compare FPV and continuous-wave (CW) Doppler parameter (PHT and slope) variations resulting from an increase in HR. METHODS: Sixty-eight patients (28 males, 40 females; mean age 52 +/- 15 years) with AR of various severity were included. Color M-mode Doppler was used in FPV, while CW Doppler was used in PHT and slope measurements. Atropine sulfate was titrated in all patients to achieve at least a 20% increase in HR. The FPV, PHT, slope and regurgitant fraction (RF) of AR were measured before and after the increase in HR. RESULTS: An increase in HR (77.8 +/- 8.9 versus 103 +/- 9.9 bpm; p < 0.001) caused a decrease in color M-mode Doppler FPV (51 +/- 21 versus 44 +/- 19 cm/s), in the PHT of the regurgitant velocity curve (468 +/- 154 versus 411 +/- 128 ms), and in the RF of the AR (30.2 +/- 16.3 versus 26.1 +/- 14%). The slope of the regurgitant velocity was increased (291 +/- 136 versus 358 +/- 122 cm/s2). All of these variations were statistically significant. CONCLUSION: An increase in HR caused a decrease in the FPV and RF of the aortic regurgitation, and both changes were signs of improved regurgitation. FPV appears to be a more valuable parameter than CW Doppler parameters in determining improvements in AR resulting from an increase in HR.
