PubMed · 8753595
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K Yamamoto, T Iga. 1995. [Digitoxin].. https://pubmed.ncbi.nlm.nih.gov/8753595/
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Contractile reserve, during low-dose dobutamine echocardiography, is frequently used for the assessment of myocardial viability in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction. Whether contractile reserve is affected by the severity of the underlying CAD is presently unknown. Accordingly, we studied 58 patients with stable CAD and LV dysfunction who underwent coronary angiography and low-dose dobutamine echocardiography. In each vascular region the worst stenosis was identified and quantitated as percent diameter stenosis. Segmental wall motion during echocardiography was scored visually and rest and dobutamine wall motion score indexes were calculated. Contractile reserve was defined as > or = 1 grade improvement in wall motion score of > or = 2 contiguous segments along with > or = 20% reduction in global wall motion score index with dobutamine. There was no difference between patients with (n = 26) and without (n = 32) contractile reserve in percent coronary stenosis (89 +/- 17% vs 87 +/- 17%, p = 0.6), number of coronary arteries with > 50% diameter stenosis (2.0 +/- 0.8 vs 2.2 +/- 0.7, p = 0.4), number of occluded coronary arteries (1.2 +/- 0.9 vs 1.1 +/- 0.9, p = 0.6), or the prevalence of collaterals demonstrated angiographically (61% vs 56%, p = 0.5). Our data demonstrates that in patients with CAD and LV dysfunction, the prevalence of contractile reserve during low-dose dobutamine echocardiography is independent of the angiographic extent and severity of CAD.
This study compares side-by-side exercise electrocardiography and dobutamine echocardiography with an invasively assessed index of myocardial flow (pressure-derived myocardial fractional flow reserve). The data show that ST-segment depression > or = 0.1 mV and the occurrence of new wall motion abnormalities during dobutamine infusion reflect a similar impairment of myocardial blood flow.
Qualitatively, dobutamine stress echocardiography has become an established procedure. Quantitative results are in great demand but this is still difficult due to limited endo- and epicardial border definition. Transmitral Doppler variables are strictly quantitative and less subjective. Furthermore, ischemic alterations precede systolic ones (ischemic cascade). There are preliminary reports of the utility of dobutamine stress Doppler echocardiography, but proof of reproducibility and left ventricular filling patterns are still lacking. Fourteen healthy volunteers (10 men, 4 women, median age 25.9 years, range 21-32 years) were investigated according to the usual dobutamine stress echocardiographic protocol (5, 10, 15, 20, 30, 40 and 40 micrograms/kg/min + 0.5 mg atropine). At each titration step a standardized transmitral PW-Doppler recording with the sample volume positioned at the opened mitral leaflet tips was analyzed three times by two independent, experienced investigators. Of the early, late, and mean velocities (VmaxE, VmaxA, Vmean), time integrals (VTI-E, VTI-A, VTI), their ratios (E/A, E/A VTI), and various time intervals (Tacc, Tdec, E- and A-duration, FillT), VmaxE (0.82 to 1.09 m/s; P < 0.0001), VTI-E (16.17 to 17.19 cm; P < 0.0001) and Vmean (0.29 to 0.82 m/s; P < 0.0001) were found to have the greatest discriminatory power, commencing already at a dose of 10-15 micrograms/kg/min dobutamine. VmaxE and VTI-E demonstrated the smallest intra- and interobserver variation without any increase in variability during incremental dose titration. Assessment of the early diastolic filling pattern by Doppler echocardiography is a valuable quantitative and reproducible adjunct to conventional dobutamine stress echocardiography. Further controlled studies in coronary artery disease patients have to confirm, whether lower dobutamine doses could be used in the test and sensitivity increased due to better data acquisition in cases of limited echogenicity, less subjectivity, and earlier onset of ischemic alterations.