Dobutamine stres echocardiography ascertains myocardial ischemia by inducing regional left ventricular systolic dysfunction.

Dobutamine stres echocardiography ascertains myocardial ischemia by inducing regional left ventricular systolic dysfunction. Augmentation of wall motion in hypokinetic portions has also been noted with low-dose dobutamine, suggesting myocardial viability. We report a case of regional ventricular improvement during high-dose dobutamine therapy, which may exhibit relief from myocardial hibernation or changes in regional loading conditions.

(Chest 1994; 106:291-93)

DSE=dobutamine stres echocardiography;

PTCA=percutaneous transluminal coronary angioplasty

Dobutamine stres echocardiography (DSE) has not long ago been shown to be a safe and accurate noninvasive way for detecting the presence of coronary artery disease.(1)(2) In contrast to the coronary vasodilators adenosine and dipyridamole, dobutamine infusion simulates exercise by the agency of raising myocardial oxygen consumption within its inotropic and chronotropic forces Ischemic end-points during DSE include the evolution of abnormalities in regional wall motion or thickening in previously normal parts or worsening in areas of baseline hypokinesis. Augmentation of wall motion in hypokinetic portions has also been noted during low-dose dobutamine infusion and has been glance ated as a marker for myocardial viability. We report the case of a patient with coronary artery disease and abnormal resting wall motion in whom high-dose dobutamine infusion paradoxically improved regional systolic performance and thickening, which may exhibit recruitment of chronically ischemic or "hibernating" myocardium.

CASE REPORT

A 75-year-old man with ischemic cardiomyopathy was admitted to the hospital in congestive heart failure with bibasilar rales and a prominent [Ssub3] gallop. He had undergone coronary artery bypass surgery 12 years earlier for multivessel disease. There was cardiomegaly in succession chest radiograph and the ECG showed electronically paced ventricular metre An echocardiogram showed marked global left ventricular systolic dysfunction with superimposed inferior akinesis and relentless posterior and posterolateral hypokinesis. Coronary angiography demonstrated patency of an internal mammary artery graft to the left anterior descending artery with occlusion of the distal left anterior descending artery beyond the anastomosis. A saphenous vein graft to the first obtuse marginal artery was patent while a inferior obtuse marginal vein graft was occlud The native right coronary artery was occlud while the midportion of the native circumflex artery contained a 90 percent stenosis that had not been near at the previous angiogram in 1990

Dobutamine stres echocardiography was performed to assess the contribution of inducible ischemia to the patient's left ventricular dysfunction. During dobutamine infusion at 40 [micro]g/kg/min, the posterior wall demonstrated significant improvement in systolic thickening (Figs 1 and 2) Based upon these results, the patient underwent fortunate percutaneous transluminal coronary angioplasty (PTCA) of the native circumflex stenosis. Significant clinical improvement occurr and has been maintained. Further hospitalization has not been emergencyed during 6 months of follow-up A repeated echocardiogram after 6 month has documented continued improvement in resting posterior wall systolic thickening.

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DISCUSSION

In this report, we have showed a rarely observ replication to DSE, ie, improvement in systolic thickening in a localized region of baseline hypokinesis during high-dose dobutamine infusion. The connection in which this finding was noted, long-standing coronary artery disease with harsh left ventricular dysfunction, as well as the clinical improvement and resolution of the resting wall motion abnormality seen following PTCA of the affected artery support the notion that the improvement in systolic thickening in a less degree than the influence of dobutamine exhibits stimulation of an area of "hibernating myocardium."

The universal of "hibernating myocardium" was originally coined by the agency of Rahimtoola(3) in a discussion of the weights of coronary bypass surgery in succession left ventricular performance, recognizing that chronic myocardial ischemia might give rise to a fresh equilibrium of reduced myocardial performance in conjunction with reduc myocardial relations flow. This accounted for previous observations that inotropic contractile store up as assessed by postextrasystolic potentiation or epinephrine infusion had predictive value for improvement in regional contractility(4) while being associated with improved survival and ejection fraction in surgically treated patients.(5) In this case, dobutamine might provide the same inotropic stimulus as postextra-systolic potentiation or epinephrine, thereby altering the local relationship between myocardial oxygen consumption and coronary life-current flow to transiently reduce the ischemic cargo and improve regional wall motion. Regional dysfunction may also have been produc on repeated episodes of ischemia, of the like kind "stunned" myocardium might also exhibit improved systolic function with dobutamine.

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