New non-invasive imaging techniques to quantify ventricular function: reappraisal of dobutamine stress echocardiography

This thesis is an insight investigation in some recently developed noninvasive imaging advances to quantitatively assess left or right ventricular function. The focus is on dobutamine stress echocardiography, with some reference to a recently developed nuclear imaging technique: Technetium-tetrofosmin-fluorodeoxyglucose- single photon emission computcd tomography (FDGSPECT). Among many attempts to pass from a subjective and qualitative to an objective and quantitative evaluation of ventricular function we analyzed Doppler tissue imaging. Left vcntricular ftmction, as stimulated by dobutaminc, was studied by applying Doppler tissue imaging as a test on myocardial ischemia and contractile reserve, the latter being even more subjected to interobserver variability, than the assessment of myocardial ischemia

Quantification of regional left ventricular function in Q wave and non-Q wave dysfunctional regions by tissue Doppler imaging in patients with ischaemic cardiomyopathy

OBJECTIVE: To quantify regional left ventricular (LV) function and contractile reserve in Q wave and non-Q wave regions in patients with previous myocardial infarction. DESIGN: An observational study. SETTING: Tertiary care centre. PATIENTS: 81 patients with previous myocardial infarction and depressed LV function. INTERVENTIONS: All patients underwent surface ECG at rest and pulsed wave tissue Doppler imaging at rest and during low dose dobutamine infusion. The left ventricle was divided into four major regions (anterior, inferoposterior, septal, and lateral). Severely hypokinetic, akinetic, and dyskinetic regions on two dimensional echocardiography at rest were considered dysfunctional. MAIN OUTCOME MEASURES: Regional myocardial systolic velocity (Vs) at rest and the change in Vs during low dose dobutamine infusion (DeltaVs) in dysfunctional regions with and without Q waves on surface ECG. RESULTS: 220 (69%) regions were dysfunctional; 60 of these regions corresponded to Q waves and 160 were not related to Q waves. Vs and DeltaVs were lower in dysfunctional than in non-dysfunctional regions (mean (SD) Vs 6.2 (1.9) cm/s v 7.1 (1.7) cm/s (p < 0.001), and DeltaVs 1.9 (1.9) cm/s v 2.6 (2.5) cm/s (p = 0.009), respectively). There were no significant differences in Vs and DeltaVs among dysfunctional regions with and without Q waves (Q wave regions: Vs 6.2 (1.8) cm/s, DeltaVs 1.6 (2.2) cm/s; non-Q wave regions: Vs 6.3 (1.9) cm/s, DeltaVs 2.0 (2.0) cm/s). CONCLUSIONS: Quantitative pulsed wave tissue Doppler demonstrated that, among dysfunctional regions, Q waves on the ECG do not indicate more severe dysfunction, and myocardial contractile reserve is comparable in Q wave and non-Q wave dysfunctional myocardium