Feasibility of pulsed-Doppler tissue imaging of the interventricular septum during exercise echocardiography

A limitation of exercise echocardiography (EE) is its semiquantitative approach in analyzing wall-motion abnormalities. However, pulsed-Doppler tissue imaging is capable of a systolic and diastolic regional quantitative assessment.

To investigate the feasibility of performing pulsed-Doppler tissue imaging sampling of the basal left ventricular (LV) septum during EE, we studied 105 consecutive patients (71 men, 34 women, aged 61 +/- 11 years). Harmonic two-dimensional (2-D) echocardiography was performed at rest and peak EE, whereas pulsed-Doppler tissue imaging was performed at rest and immediately after EE. Adequate recordings for peak systolic velocity (Vs) were possible in all patients, but peak early diastolic (Ve) and peak late diastolic (Va) velocities were possible in 78 (74%) patients. Positive 2-D echocardiography was considered as infarction or an ischemic response.

Forty-five (43%) patients (Group 1) had wall-motion abnormalities involving the left anterior descending artery (LAD) territory (29 with ischemia, 11 with ischemia and necrosis, and 5 with necrosis), 21 (20%) (Group 2a) had wall-motion abnormalities involving the left circumflex (LCX) and/or the right coronary artery (RCA) territories, and 39 (37%) (Group 2b) had normal EE. Heart rate increased from 72 +/- 17 beats/min to 143 +/- 18 beats/min (P < 0.0001) and systolic blood pressure from 129 +/- 19 mmHg to 174 +/- 26 mmHg (P < 0.001). Coronary angiography was performed in 30 (29%) patients, 29 of whom had positive findings on EE. LAD or diagonal branch coronary artery disease (CAD) (> or = 50% luminal narrowing) was present in 22 patients, 10 of whom had proximal severe stenosis (> or = 70% luminal narrowing). Vs increase was significatively lower in Group 1 (40 +/- 35%, from 6.0 +/- 1.5 cm/sec to 8.1 +/- 2.2 cm/sec) than Group 2a (75 +/- 35%, from 6.3 +/- 1.4 cm/sec to 10.8 +/- 2.1 cm/sec, P < 0.0001) and Group 2b (64 +/- 27%, from 6.7 +/- 1.3 cm/sec to 10.9 +/- 2.0 cm/sec, P < 0.001). Ve was not different at rest and at postexercise between groups. Va was similar at rest but higher at postexercise in Group 2b than Group 1 (11.8 +/- 2.3 cm/sec vs 10.3 +/- 3.0 cm/sec, P < 0.05). Failure to achieve Vs > or = 9.5 cm/sec after exercise was found to be the more accurate limit to detect necrosis or ischemia in the LAD territory according to EE criteria (sensitivity 76%, specificity 78%). When analysis was limited to the 30 patients who underwent angiography, we found that the 10 patients with proximal severe LAD or diagonal branch stenosis showed blunted increases in Vs (increase 9.4 +/- 19%, from 6.5 +/- 1.2 cm/sec at rest to 7.4 +/- 1.7 cm/sec at post-EE; P = 0.17) in contrast to the 20 patients having moderate or nonsignificant stenosis (increase 31 +/- 20%, from 6.2 +/- 1.5 cm/sec at rest to 9.3 +/- 1.8 cm/sec at post-EE, P < 0.0001). A failure to increase Vs > or = 30% had a sensitivity of 90% and a specificity of 80% in detecting proximal severe stenosis.

Pulsed-Doppler tissue imaging sampling of the LV septum is feasible technically during EE and allows quantification of the regional response. This method may be accurate for detecting proximal severe stenosis in vessels supplying the LAD territory.