Alan D. Waggoner

Cardiac resynchronization therapy (CRT) is beneficial for a majority of patients with medically refractory heart failure due to severe left ventricular (LV) systolic dysfunction and prolonged interventricular conduction to improve symptoms and LV performance. An optimally programmed atrioventricular delay (AVD) during CRT can be also important to maximize the response in left ventricular function. Several Doppler echocardiographic methods have been reported to be useful for determination of the optimal AVD. This review will discuss the various Doppler‐based approaches to program the AVD in patients that receive CRT.

The standard noninvasive method to assess left ventricular diastolic function has been pulsed Doppler echocardiographic recordings of mitral inflow early diastolic (E) and atrial (A) filling velocities and the ratio of E to A, in combination with isovolumic relaxation and deceleration times. Pulmonary venous inflow velocities (systolic, diastolic, and atrial reversal) are used to assess left atrial and left ventricular end-diastolic pressures. These measurements are influenced by changes in preload, including left ventricular end-diastolic pressure, left atrial or pulmonary capillary wedge pressure, and left ventricular volumes. Newer methods such as tissue Doppler imaging (TDI) of the mitral annulus and color M-mode recording of left ventricular diastolic flow propagation (FP) have now evolved as additional techniques for detecting abnormalities in left ventricular diastolic function that can complement the standard pulsed Doppler echocardiography methods. Both TDI and color M-mode flow FP appear to offer distinct advantages as relatively load-independent measures of diastolic function. TDI can be used for measurement of regional diastolic myocardial velocities at the mitral annulus, and it is particularly useful in identifying abnormalities of left ventricular diastolic relaxation or estimation of left ventricular filling pressures. Color M-mode FP can be used for quantification of abnormalities of left ventricular relaxation and diastolic filling characteristics of the left ventricle.