Monophasic transmitral flow pattern with less increase in heart rate indicates left ventricular dysfunction.

When heart rate (HR) increases, mitral flow can become monophasic. Prolonged isovolumic contraction and relaxation time (ICT and IRT), directly related to left ventricular (LV) function, can potentially influence the HR with monophasic mitral flow. The present study investigated the relation between HR that causes monophasic flow and LV function. During diagnostic catheterization, HR was increased using right atrial pacing by 2 beats/min every 2 min in a stepwise manner until the development of monophasic mitral flow in 17 patients with normal sinus rhythm. ICT, IRT, end-diastolic and end-systolic LV volumes, LV ejection fraction, LV peak + and -dP/dt, peak (+dP/dt)/P, and the relaxation time constant (tau) were measured by Doppler echocardiography or catheterization when monophasic mitral flow developed. The monophasic HR varied from 74 to 106 beats/min. By univariate analysis, ICT (p<0.01, r2=0.73), LV peak +dP/dt (p<0.05, r2=0.37), peak (+dP/dt)/P (p<0.01, r2=0.71), peak -dP/dt (p<0.05, r2=0.25), and tau (p<0.05, r2=0.33) had a significant correlation with monophasic HR. By multivariate analysis, prolonged ICT and reduced LV peak -dP/dt independently contributed to monophasic mitral flow with less increase in HR. Monophasic mitral flow with less increase in HR indicates impaired LV systolic and diastolic function during isovolumic contraction and relaxation.