Considering longitudinal LV dynamics from the apical view on routine ECG examination, movement towards the transducer occurs during systole and movement away from the transducer in diastole. This is opposite of mitral inflow where movement is towards the transducer in diastole. Figure 1 shows color-coded mitral annular velocity from an apical four-chamber view.

The contractile process is illustrated in Figure 2. Interaction of the actin and myosin filaments consumes ATP in systole causing a shortening of the myofibril and in early diastole causing myofibril lengthening. Energy is consumed throughout the contractile process, so the early diastolic "E" wave is an active process that contributes to LV suction and is affected by myocardial diseases, such as ischemia, infiltrative processes (cardiac amyloidosis), or transplant rejection. TD and the longitudinal expansion velocities have clinical relevance and application because of these physiologic processes.

Mitral annular motion and myocardial velocity gradient on TD may be useful for detecting abnormalities in ventricular function, and could potentially reduce the number of biopsies (minimum 10/yr) that heart transplant patients must undergo to predict rejection. Preliminary data are promising and give hope that the number of biopsies at least could be reduced; more work is needed before biopsies can be eliminated.

In a patient with moderate rejection, diminished systolic velocity gradient and early diastolic gradient is seen. The mitral annular velocity is affected in systole and in particular in diastole, showing a markedly diminished E wave amplitude. In another patient who underwent sequential TD studies during moderate rejection and then TD studies 6 months later, no rejection was seen as evidenced by the increases in systolic and diastolic velocity gradients and a more normal pattern of mitral annular velocity.

In 84 patients who underwent TD studies at the time of biopsy it was shown that mitral annular velocity (combined systolic and diastolic peak velocities) was the most predictive of transplant rejection. The data had a 93% sensitivity, 71% specificity, and a 98% negative predictive value.

This is an exciting area now being applied in Gorscan's lab, although these are rare diseases. Constrictive pericarditis adversely affects ventricular filling. Cardiac amyloidosis, an infiltrative disease, has profound effects on diastolic function. Constrictive pericarditis is treatable and can possibly be cured with surgery, whereas cardiac amyloidosis has a poor prognosis. In constrictive pericarditis there is a peculiar filling abnormality with a rapid increase in diastolic pressures followed by a plateau, as shown by simultaneous hemodynamic tracings from the right atrium, pulmonary artery, right ventricle, and left ventricle. A similar pattern can be seen with restrictive disease, making differentiation difficult.

In constrictive pericarditis, the E wave is preserved on color TD, whereas the E wave velocity is diminished in restrictive cardiomyopathy, as shown in Figure 3. Pulse TD also shows the very diminished E wave velocity in early diastole in restrictive cardiomyopathy. Supportive data from the Cleveland Clinic shows that mitral inflow and mitral annular velocity can be used to differentiate restriction from constriction.

Gorscan recommends these general guidelines to differentiate these two diseases: In restrictive disease, the peak E wave is usually less than 10 cm/sec with pulsed TD and is usually less than 7 cm/sec with color TD. Pulsed and color TD can be applied as complementary techniques to mitral inflow and other data.

TD is used to assess LV filling pressures in routine clinical practice at the University of Pittsburgh, and is an exciting advance. Color-coded TD represents mean velocities throughout the cardiac cycle, so the peak systolic or diastolic velocity will be much less compared with pulsed TD.

The ratio of mitral inflow velocity is compared to the mitral annular velocity to predict LV filling pressure. The inflow-to-annular (E/Ea) ratio has been shown to correlate with mean pulmonary capillary wedge pressure (PCWP) in a series of patients with both normal and abnormal LV ejection fractions. In patients with an E/Ea > 10, there is a 92% sensitivity and an 80% specificity for having an elevated filling pressure greater than 15 mm Hg. In 180 patients with normal sinus rhythm or sinus tachycardia TD was also shown to be useful (R=0.87), representing another novel opportunity to assess filling pressures.