A comparison of dobutamine infusion and exercise during radionuclide ventriculography in the evaluation of coronary arterial disease

Dobutamine stress surface mapping of myocardial ischemia in Kawasaki disease

BACKGROUND

To detect and localize myocardial ischemia, a method that does not require physical exertion is sometimes needed in children with Kawasaki disease.

METHODS

Dobutamine stress body surface mapping was performed in 115 children with a history of Kawasaki disease (58 without coronary artery lesions, 40 who had coronary lesions without myocardial ischemia and 17 with myocardial ischemia). The maximum infusion rate of dobutamine was 30 microg/kg per min. Myocardial ischemia was diagnosed by the presence of an area of hypoperfusion on scintigraphy at rest and/or an increase in hypoperfusion during a dobutamine stress test compared with resting scintigraphy. We studied the number of leads that showed significant ST depression on the isopotential map (nST), the number of the row containing the lead with the smallest negative value on the isointegral map (I(min)), and the localization of myocardial ischemia on the isointegral map. Based on findings in patients without coronary artery lesions, we defined the criteria for detecting myocardial ischemia as nST > or = 1 and I(min) < or = 4.

RESULTS

The sensitivity of detecting myocardial ischemia was 94.1% using nST and 41.7% using I(min), while the specificity of these methods was 98.9 and 96.9%, respectively. The localization of myocardial ischemia on stress body surface mapping was 100% concordant with that determined by stress myocardial scintigraphy.

CONCLUSIONS

Dobutamine stress body surface mapping for the detection of myocardial ischemia is a non-invasive, more convenient and repeatable test compared with exercise myocardial scintigraphy and it is a more objective test compared with exercise echocardiography. Dobutamine stress body surface mapping is useful for the identification and localization of silent myocardial ischemia in pediatric patients with Kawasaki disease, especially those who cannot perform tests involving physical exercise.

Changes in endothelium-derived vascular regulatory factors during dobutamine-stress-induced silent myocardial ischemia in patients with Kawasaki disease

The changes in endothelium-derived vascular regulatory factors during dobutamine (DOB)-induced myocardial ischemia (MI) were investigated in 21 patients with Kawasaki disease aged from 11 months to 18 years. They were classified into an ischemia group (8 patients) and a non-ischemia group (13 patients) based on the results of 99mTc myocardial scintigraphy and DOB stress 99mTc myocardial scintigraphy. In the ischemia group, MI was relatively mild, because there were ischemic changes on the electrocardiogram and no significant symptoms during DOB stress. Catheters were positioned near the orifice of the coronary artery (Ao) and at the coronary sinus (CS). Hemodynamics and the blood concentrations of lactic acid and endothelin-1, as well as NO3-, 6-keto-prostaglandin F1alpha, and thromboxane B2, (which are inactive metabolites of nitric oxide, prostaglandin I2 and thromboxane A2, respectively), were measured at rest and after DOB stress (maximum dose: 30 microg x kg(-1) x min(-1)). The CS/Ao ratio was determined for all parameters. The rate-pressure product, an index of work load, and the cardiac index were significantly increased by DOB stress in both groups. Coronary angiography showed no vasospasm of the epicardial coronary arteries before or after DOB stress in either group. The plasma concentrations of endothelin-1 and 6-keto-prostaglandin F1alpha were significantly increased after DOB stress in the ischemia group, but the serum concentration of NO did not increase. The lack of an increase in NO production during DOB stress may have contributed to the worsening of MI in patients with Kawasaki disease.

Evaluation of myocardial ischemia in Kawasaki disease by dobutamine stress signal-averaged ventricular late potentials

OBJECTIVE

To determine the possibility of diagnosing myocardial ischemia from signal-averaged electrocardiographic late potentials (LPs) in patients with Kawasaki disease.

METHODS

Dobutamine stress LPs were obtained in 85 children with a history of Kawasaki disease (48 without coronary artery lesions, 19 with coronary artery lesions without myocardial ischemia, and 18 with myocardial ischemia). The infusion of dobutamine was started at 5 micrograms/kg/min, increased to 30 micrograms/kg/min. The presence of LPs was determined by the filtered QRS duration, the root mean square voltage during the last 40 ms, and the duration of the signal under 40 microV.

RESULTS

Among the children without coronary lesions, LPs were detected in 4.2% at rest and in 2.1% with dobutamine stress. Among the group with coronary lesions but without ischemia, LPs were found in 5.3% at rest and in 5.3% with stress. In the group with ischemia, LPs were present in 44.4% at rest and in 77.8% with stress. The sensitivity for myocardial ischemia was 72.7% at rest and 87.5% with stress (p < 0.05), and the specificity was 86.5% at rest and 94.2% with stress.

CONCLUSION

LPs associated with dobutamine stress testing are useful for identifying myocardial ischemia in children with Kawasaki disease, especially in those who cannot tolerate testing involving physical exercise.

Comparison of dobutamine infusion and exercise during radionuclide ventriculography in the risk stratification after acute myocardial infarction

Forty-eight patients with acute myocardial infarction were subjected to radionuclide ventriculography during exercise and dobutamine infusion after a mean duration of 25 +/- 18 days following acute myocardial infarction. The results were compared and correlated with coronary angiography. Two patterns of abnormal response of radionuclide ventriculography were identified: (1) a worsening of the baseline wall motion abnormality confined to the infarcted area, and (2) fresh regional wall motion abnormalities in areas with normal motion at rest. Of 44 patients with significant coronary artery lesions (> or = 70% diameter stenosis), 18 had single vessel disease and 26 had multivessel disease. Dobutamine and exercise radionuclide ventriculography identified 23 and 21, respectively, of 26 multivessel disease patients yielding sensitivities of 88% and 80%. Seven of 18 single vessel disease patients showed a worsening of baseline wall motion abnormality of infarct area on dobutamine infusion radionuclide ventriculography. Subgroup analysis of coronary angiograms of single vessel disease revealed that 10 of 18 patients had subtotal occlusion of infarct-related artery supplying a hypokinetic area and the rest had a totally occluded coronary artery supplying an akinetic area. Dobutamine infusion and exercise radionuclide ventriculography detected 7 and 6 of these 10 patients implying the presence of jeopardized myocardium in infarcted/peri-infarct area. Dobutamine stress radionuclide ventriculography is an acceptable alternative to exercise testing to stratify risk following acute myocardial infarction.

The dobutamine stress test with thallium-201 single-photon emission computed tomography and radionuclide angiography: postinfarction study

OBJECTIVES

The purpose of this study was to investigate left ventricular wall motion changes during dobutamine-induced myocardial ischemia.

BACKGROUND

Dobutamine is increasingly used as a stress test. It has been assumed that high doses of the drug induce the same changes in contractility as physical exercise. However, some data suggest that ischemic myocardium can respond to dobutamine with an increase in contractility.

METHODS

Sixty-three postinfarction patients twice underwent the dobutamine test (up to 40 micrograms/kg per min) within 1 to 2 days. Thallium-201 single-photon emission computed tomography (SPECT) and gated equilibrium radionuclide ventriculography were performed on each patient at rest and with dobutamine. Both global and regional ejection fractions were quantified. Sixty patients underwent coronary cineangiography within 1 week. The presence of redistribution was correlated with global and regional ejection fraction changes and with coronary lesions.

RESULTS

Redistribution was present in 45 patients, and no change or a decrease in global or regional ejection fraction was detected in 22. In the entire group of patients global ejection fraction increased from 46 +/- 12% to 56 +/- 14%. The six patients with triple-vessel disease had a flat (-0.2 +/- 5%) ejection fraction response to dobutamine, whereas the remaining patients had an increase of 11 +/- 7% (p = 0.003). The regional ejection fraction of the hypokinetic area increased from 27 +/- 10% to 41 +/- 19%, showing no change or a decrease in 13 patients. The 44 patients with peri-infarct redistribution had a significantly higher increase in regional ejection fraction than those without redistribution (16.4 +/- 10% vs. 4.7 +/- 17%, p = 0.003). In the patients with peri-infarct redistribution, an inverse linear correlation was found between redistribution score and dobutamine-induced regional ejection fraction change (r = -0.44, p = 0.004).

CONCLUSIONS

Mild to moderate dobutamine-induced peri-infarct ischemia is compatible with an increase in contractility, whereas severe ischemia induces worsening of wall motion.