Dobutamine Test Research Articles

Comparing a High-Dose Dipyridamole SPECT Imaging Protocol with Dobutamine and Exercise Stress Testing Protocols. Part II: Using High-Dose Dipyridamole to Determine Lung-to-Heart Ratios

Comparing a High-Dose Dipyridamole SPECT Imaging Protocol with Dobutamine and Exercise Stress Testing Protocols. Part II: Using High-Dose Dipyridamole to Determine Lung-to-Heart Ratios

Ventricular Arrhythmias During High-Dose Dobutamine Test in Patients With Dilated Cardiomyopathy and Heart Failure

Ventricular Arrhythmias During High-Dose Dobutamine Test in Patients With Dilated Cardiomyopathy and Heart Failure

Coronary Vasospasm as a Source of False Positive Results During Dobutamine Echocardiography

Several studies have demonstrated a consistently high sensitivity of dobutamine echocardiography whereas test specificity in these series has been variable. The aim of this study was to evaluate whether coronary vasospasm--elicited by alpha1 adrenoreceptor stimulation--may be a significant source of false positive responses during dobutamine stress.From the data bank of four institutions we selected 113 patients (75 males, 38 females, mean age 55 +/- 12 years) with dobutamine echocardiography performed (up to 40 micrograms/kg/min and atropine 1 mg if needed) before a coronary angiography showing normal or near normal (visually assessed stenosis severity < 50%) coronary arteries. The following variables--which were previously reported influencing dobutamine echo specificity--entered the multivariate statistical analysis: age, sex, heart rate at baseline and at peak stress, baseline echo, hypertension, site of asynergy, and spasm at coronary angiography.Twenty-five patients had a positive dobutamine test. The positivity occurred in the left coronary territory in 15 and in the right coronary territory in 10 cases. All the 6 patients with spontaneous spasm during angiography had a false positive stress test result. By multivariate analysis only coronary artery spasm during angiography (p = 0.0015) and history of hypertension (p = 0.0031) were significant predictors of false positive results of dobutamine stress echocardiography.Coronary artery spasm may be an important source of false positive results during dobutamine stress echocardiography.

Ventricular arrhythmias during high-dose dobutamine test in patients with dilated cardiomyopathy and heart failure

Ventricular arrhythmias during high-dose dobutamine test in patients with dilated cardiomyopathy and heart failure

Comparison of Dobutamine and Treadmill Exercise Echocardiography in Inducing Ischemia in Patients With Coronary Artery Disease

Objectives. We sought to compare the magnitude of ischemia precipitated by both treadmill exercise and dobutamine stress echocardiography.Background. Although it is alleged that dobutamine stress produces ischemia similar in degree and extent to that produced during treadmill exercise, a direct comparison with treadmill exercise, the most common form of exercise, has not been performed.Methods. Eighty-five consecutive patients with known coronary artery disease underwent both stress tests on the same day, in random order.Results. Sixty-two patients (73%) had positive results on exercise echocardiography compared with 53 (62%) who had positive results on dobutamine stress (p = NS). Of the 53 patients with positive dobutamine test results, wall motion abnormalities appeared after the addition of atropine in 35 patients (66%). During dobutamine infusion, 22 patients (26%) had a hypotensive response that was reversed in 16 by prompt administration of atropine. At peak dobutamine–atropine stress, heart rate was higher than that at peak exercise (p < 0.001), whereas systolic blood pressure and rate–pressure product were higher at peak exercise than at peak dobutamine–atropine stress (p = 0.0001). In the 53 patients with positive results on both tests, peak wall motion score index was greater with treadmill exercise than with dobutamine–atropine infusion ([mean ± SD] 1.73 ± 0.45 vs. 1.57 ± 0.44, p < 0.001).Conclusions. Echocardiography immediately after treadmill exercise induces a greater ischemic burden than dobutamine–atropine infusion. In the clinical setting, exercise echocardiography should therefore be chosen over dobutamine echocardiography for diagnosing ischemia, when possible. When dobutamine echocardiography is used as an alternative modality, maximal heart rate should always be achieved by the addition of atropine.

Diagnostic and Prognostic Value of Dipyridamole and Dobutamine Stress Echocardiography in Patients With Q-Wave Acute Myocardial Infarction

The aim of this study was to compare dipyridamole and dobutamine stress echocardiography, performed early in patients with acute myocardial infarction (AMI) to evaluate residual ischemia, viability, and prognosis. Fifty patients (mean age 55 ± 9 years, 47 men, 3 women) with AMI, all treated with thrombolytic therapy, underwent standard dipyridamole and dobutamine tests, within the fifth day of the event. Wall motion score index and the 16 segments model were used to evaluate contractility. Forty-seven patients underwent coronary angiography within the tenth day of the event. The mean follow-up was 24 ± 12 months. No side effects occurred during both tests. Both dipyridamole and dobutamine tests were positive for ischemia, in 32 and 33 of 47 patients, respectively (sensitivity 73% and 75%; specificity 67% and 67%); these tests induced an improvement of contractility in 23 and 38 of 139 abnormal segments at baseline, respectively (sensitivity 52% and 86%; specificity 100% and 100%). Cardiac events occurred in 26 of 50 patients, 22 with a positive dipyridamole test and 21 with positive dobutamine test. Thus, both tests were feasible, safe, and useful to evaluate residual ischemia, viability, and prognosis. No significant differences were found in sensitivity and specificity between tests.

Comparison of dobutamine ECG stress test with predischarge exercise test after acute myocardial infarction

Exercise testing after acute myocardial infarction is commonly used, but in recent years alternative methods have been proposed. Standard exercise testing was compared with dobutamine electrocardiographic (ECG) stress testing in 100 patients after an acute initial myocardial infarction. Dobutamine ECG stress testing was performed in a standard manner at 5 ± 1 days after the infarction and exercise testing was performed a mean of 10 ± 2 days following the event. Agreement between both tests was observed in 91 cases (91%), P < .001, Fisher test kappa value, 0.79). The dobutamine test predicted the result of the exercise test with a sensitivity of 100% (95% confidence interval, 87–100) and a specificity of 88% (95% confidence interval 77–93) for a positive predictive value of 75% (95% confidence interval, 62–97) and a negative predictive value of 100% (95% confidence interval, 91–100). Dobutamine ECG stress testing is concluded to be an objective and reliable procedure, which accurately predicts the results of standard exercise testing. It is inexpensive, easy to perform, and although not yet confirmed, could be particularly useful in patients who cannot perform exercise.

Long-Term Prognostic Significance of Dobutamine Echocardiography in Patients With Suspected Coronary Artery Disease: Results of a 5-Year Follow-Up Study

Objectives. This study sought to assess the long-term prognostic utility of dobutamine stress echocardiography in predicting fatal and nonfatal cardiac events.Background. Although dobutamine stress echocardiography has improved sensitivity and specificity for detection of coronary artery disease, little is known of its predictive value for long-term cardiac events. Therefore, we followed up 120 consecutive patients who underwent dobutamine echocardiography for suspected coronary disease from March 1989 to August 1991.Methods. All patients presenting for coronary angiography for chest pain were eligible for recruitment. Follow-up was 100% complete at 5 years (range 3.0 to 6.1). Cardiac events were defined as cardiac death or nonfatal myocardial infarction or the need for coronary revascularization (coronary angioplasty or bypass surgery).Results. Positive (n = 78) and negative (n = 42) dobutamine test groups differed in their rates of coronary artery bypass graft surgery (37.2% vs. 9.5%, p < 0.001, respectively) and mortality. Of 26 total deaths, 22 occurred in the group with positive dobutamine test results (28% vs. 9.5%, p < 0.018); all 7 cardiac deaths occurred in this group as well (9% vs. 0%, p < 0.045). By multivariate regression analysis, positive results on dobutamine echocardiography remained independently predictive of future cardiac death after left ventricular ejection fraction and other clinical variables were accounted for.Conclusions. A positive finding on dobutamine echocardiography is an independent predictor of long-term cardiac mortality, whereas a negative finding confers a significantly reduced likelihood of cardiac death as much as 5 years from initial testing. We conclude that dobutamine stress echocardiography can be used to predict which patients with suspected coronary artery disease are at low risk for cardiac death and do not require concurrent nuclear or invasive testing.(J Am Coll Cardiol 1997;29:969–73)© 1997 by the American College of Cardiology

Predictive value of dobutamine radionuclide ventriculography in detection of functional improvement after acute anterior wall infarction and thrombolytic therapy.

Prolonged postischemic ventricular dysfunction (stunned myocardium) may prevent the assessment of myocardial salvage early after thrombolysis. Dobutamine in conjunction with radionuclide ventriculography has been proposed for the early assessment of myocardial viability and prediction of functional recovery. This study was designed to investigate the effects of low-dose dobutamine infusion on early global and regional function of reperfused myocardium after acute anterior wall myocardial infarction (MI). In particular, our purpose was to examine whether this response can predict late recovery of left ventricular function and correlate with the reperfused status (patency of infarct-related artery). In all, 29 consecutive patients with first uncomplicated anterior wall MI, and who had received thrombolytic therapy, underwent radionuclide ventriculography at rest and 2 min after each dose increment of dobutamine infusion (5-15 micrograms/kg/min) on the third day after the infarction, at discharge, and at 3 months' follow-up. Global and regional ejection fraction were calculated at each stage. Four patients with complications were dropped from the study. A significant response to dobutamine was defined as an increase of at least > or = 7% in global or regional ejection fraction at the infarct zones. Of the 25 patients, 18 (72%) fulfilled these criteria. Of these, 10 patients (56%) had a significant improvement in global or regional ejection fraction at discharge and 13 patients (72%) at 3-month follow-up. The overall sensitivity of the dobutamine test in predicting left ventricular improvement was 100% at discharge and 93% at 3-month follow-up. However, the positive and negative predictive values were 56 and 100% at discharge and 72 and 86%, respectively, at 3-month follow-up. Low-dose dobutamine radionuclide ventriculography is a safe and useful test for assessing myocardial viability and may predict late functional improvement in patients with anterior wall MI.

Normal values of SvO2 as therapeutic goal in patients with multiple injuries.

To determine whether maintaining normal levels of mixed venous oxygen saturation (SvO2) in patients with multiple injuries is more relevant to survival than maintaining above-normal levels of oxygen transport. Non-randomised, retrospective control study over a 38-month period. Multidisciplinary intensive care unit in a university hospital. 40 patients with multiple injuries divided in to group A (23 patients) and group B (17 patients). In group A patients, we maintained normal SvO2 by manipulation of oxygen transport variables: oxygen delivery (DO2) was increased only if SvO2 decreased or the dobutamine test was positive. In group B patients, DO2 was routinely maintained at above-normal levels by aggressive use of fluids and dobutamine. In group A we measured SvO2 continuously and performed the dobutamine test. Oxygen transport-related variables were recorded every 12 h in the first 5 days after injury in both groups, as well as lactate concentrations. Survival was significantly greater in group A than in group B (p < 0.01). Multiple organ failure was less frequent in group A than in group B (p < 0.01). The average DO2 in group A was significantly lower than in group B from day 2 onwards (p < 0.05-0.01). Average values of DO2 of 605-688 ml/ min per m2 were required to maintain normal SvO2 and aerobic metabolism in group A; 10 patients required dobutamine 2.5-5 micrograms/kg per min. The average DO2 in group B was 622 ml/ min per m2 on day 1 and then it increased to 835 ml/min per m2 on day 5 after trauma. Our results indicate that for patients with multiple injuries maintaining normal SvO2 values and increasing DO2 only if required are more relevant for survival than routine maintenance of above-normal oxygen transport values.

Signos predictores de enfermedad coronaria multivaso en la ecocardiografía con dobutamina

To assess the ability of dobutamine echocardiography to detect multivessel coronary artery disease and to determine predictive factors for multivessel disease with or without beta-blockers. A total of 101 patients underwent dobutamine stress echocardiography and coronary angiography (evaluation of chest pain 76, extent of coronary disease after myocardial infarction 19, other indications 6). Ten patients in whom the test was prematurely terminated were excluded. Out of 91 patients who underwent dobutamine echocardiography, 54 patients had multivessel disease (sensitivity of dobutamine test 93%, specificity 46%). Heart rate at the maximum dose of dobutamine or atropine was 88 +/- 21 beats/min for multivessel diseases and 104 +/- 21 beats/min without multivessel disease (p < 0.001). A cut-off value < 94 beats/min discriminated patients at risk for multivessel disease. After adjusting for treatment with beta-blockers, heart rate < 94 beats/min, ECG signs of ischemia, and abnormalities on baseline echocardiogram with remote asynergies during dobutamine testing were independent predictors of multivessel disease in the multivariate analysis (probability > 90% when at least two factors were present). A heart rate < 94 beats/min at peak dose of dobutamine or after atropine, ECG signs of ischemia, and the presence of abnormalities on echocardiogram at rest with remote asynergies during dobutamine stress testing were independent predictive factors of multivessel coronary artery disease.

Effects of Beta-Blockade and Atropine on Ischemic Responses in Left Ventricular Regions Subtending Coronary Stenosis During Dobutamine Stress Echocardiography

This study was designed to examine the effects of a beta-adrenergic blocking agent on the ischemic response to dobutamine stress and to determine the degree to which these effects can be abolished by the addition of atropine. Whether beta-blockade affects the sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease has been controversial. In nine pigs, a left anterior descending coronary artery stenosis was created to reduce flow reserve (maximal/rest flow) to 1.1 to 1.9 without baseline regional wall motion abnormalities. This corresponded to a 50% to 90% diameter stenosis. Wall thickening was measured using epicardial echocardiography. Regional lactate production and coronary venous pH were monitored from an adjacent cardiac vein. A standard protocol of dobutamine stress echocardiography was first performed. After normalization of the ischemic abnormalities elicited with this infusion, esmolol was infused at 50 micrograms/kg body weight per min and the dobutamine test was repeated, with 1.0 mg of atropine added at the maximal dobutamine dose. Without esmolol, dobutamine stress induced myocardial ischemia with a reduction in regional wall thickening and lactate production in all nine pigs. Multiple regression analysis revealed that coronary flow per heartbeat (p < 0.01) and lactate production (p < 0.05) independently correlated with regional wall thickening during dobutamine stress. The beta-blocker significantly reduced heart rate and regional oxygen consumption and altered the relation between coronary flow per heartbeat and regional wall thickening (p < 0.05) during dobutamine stress. Esmolol prevented dobutamine-induced ischemia (lactate production and wall motion abnormalities) in seven of nine pigs. The addition of atropine induced lactate production and a reduction in wall thickening in five of seven pigs in which ischemia had been prevented by beta-blockade. However, lactate production was higher and regional venous pH was lower with the baseline dobutamine infusion than with that performed after esmolol with atropine added at the maximal dobutamine dose (p < 0.05). A correlation between regional wall thickening and coronary flow per heartbeat was demonstrated during baseline dobutamine stress. Beta-blockade shifted this relation so that dobutamine stress-induced myocardial ischemia was attenuated. The mechanisms by which beta-blockade prevents dobutamine-induced ischemia appeared to be mainly through decreases in heart rate and rate of rise in left ventricular pressure, improvement of regional coronary flow per heartbeat and attenuation of regional ischemic lactate production. Adding atropine in conventional doses enhanced the ability of dobutamine stress to induce myocardial ischemia but did not completely abolish the effects of beta-blockade on either the severity of dobutamine-induced wall thickening abnormalities or regional metabolic disturbances.

Impact of Beta Blockers on Dobutamine-Atropine Stress Echocardiography.

Dobutamine increases oxygen demand in the myocardium and is used in conjunction with echocardiography to detect coronary artery disease. Beta blockers (BB) are partial antagonists of dobutamine and, therefore, offset dobutamine effects. Still, the impact of BB therapy on dobutamine stress echocardiography is not clear. One hundred forty-one dobutamine-atropine echocardiographic studies have retrospectively been analyzed: 27 patients were on BB (19%; group I); and 114 off BB (81%; group II). Coronary angiography was performed in a similar percentage of patients (97% and 85%, respectively; P = NS). No differences in clinical and angiographic profile were found between the groups. Sensitivity (83% vs 71%; P = NS) and specificity (100% vs 95%; P = NS) for coronary artery disease were similar in both groups. Atropine was infused more frequently to patients from group I (67% vs 46%; P = 0.04). Limiting side effects and prolonged ischemia presented with the same frequency in both groups. When the dobutamine test was positive, severe extent of ischemia appeared more often in patients from group I than in patients from group II (66% vs 33%; P = 0.03). The majority of patients from group I (55%) with severe extent of ischemia and only 12% from group II received atropine (P = 0.02). No differences were found in dobutamine time and extent of ischemia in patients from group I who had a positive response to dobutamine. On the contrary, patients from group II with one vessel disease had a dobutamine time longer (10.5 +/- 3.8 vs 7.8 +/- 3.7 min; P < 0.05) and extent of ischemia smaller (1.8 +/- 0.4 vs 2.6 +/- 0.5 segments; P < 0.05) than patients from group II with multivessel disease. We conclude that: 1) sensitivity of dobutamine-atropine echocardiography for diagnosis of coronary artery disease remains even if patients are on BB; 2) patients with significant coronary artery disease who are taking BB often develop severe myocardial ischemia during dobutamine-atropine stress echocardiography; and 3) BB therapy precludes stratification of a positive echocardiographic response. These conclusions should be confirmed in a prospective study to be considered as definitive. (ECHOCARDIOGRAPHY, Volume 13, July 1996)

Stress echocardiography in elderly patients with coronary artery disease Applicability, safety and prognostic value of dobutamine and adenosine echocardiography in elderly patients

Objectives. Our aim was to determine the applicability, safety and prognostic value of adenosine and dobutamine stress echocardiography in patients ≥70 years old.Background. These tests are sometimes mandatory because of difficulties and inaccuracies in interpreting traditional electrocardiographic stress tests. Furthermore, if these tests could be used to avoid coronary arteriography and cardiac catheterization, they would become essential in the care of the elderly, whose numbers are increasing.Methods. We performed coronary arteriography and dobutamine and adenosine stress echocardiographic tests in 120 patients (72 men) ≥70 years old who entered the hospital because of chest pain and had known or suspected coronary artery disease. The stress tests were performed on separate days, within 2 weeks of coronary arteriography. Both the arteriograms and the echocardiograms were analyzed by two experts who had no knowledge of the patients' other data or the other interpreter's report. Tests were judged to have positive or negative results, and the patients were followed up for the development of cardiac events. Univariate and multivariate analyses and other statistical modalities were applied for comparisons.Results. Documented coronary artery disease was found in 89 patients. During the 14 ± 7 months of follow-up, cardiac events developed in 50 patients, including 3 (7.9%) of 38 patients with negative dobutamine and 12 (20.7%) of 58 patients with negative adenosine test results. Demonstration of any abnormality on stress echocardiography was an independent factor for cardiac events, both for dobutamine (relative risk 7.3) and for adenosine (relative risk 3.0). Both cessation of dobutamine or adenosine tests and diagnosis of disease in two or more coronary vessels were also independent predictors. ST segment depression ≥1 mm was related to future events only with the dobutamine test.Conclusions. These echocardiographic stress tests proved safe and well tolerated. They successfully stratified this cohort of elderly patients with coronary artery disease to low or high risk subgroups for subsequent cardiac events.

Combined low dose dipyridamole-dobutamine stress echocardiography to identify myocardial viability

Objectives. We sought to evaluate the effects of combined administration of infra-low dose dipyridamole and low dose dobutamine on assessment of myocardial viability.Background. Low dose pharmacologic stress echocardiography with either dobutamine or dipyridamolc infusion has been proposed for the recognition of myocardial viability.Methods. Thirty-four patients with rest wall motion dyssynergy by two-dimensional echocardiography and with angiographically proved coronary artery disease underwent in combination with two-dimensional echocardiographic monitoring: 1) low dose (5 to 10 μg/kg per min over 3 min) dobutamine infusion; 2) infra-low dose (0.28 mg/kg over 4 min) dipyridamole infusion; 3) combination of infra-low dose dipyridamole infusion immediately followed by low dose dobutamine infusion (combined dipyridamole-dobutamine).Results. Follow-up rest echocardiography was available in 30 patients. After revascularization, 82 segments showed a contractile improvement of ≥1 grade, whereas 63 segments remained unchanged. The sensitivity of dobutamine, dipyridamole and combined dipyridamole-dobutamine for predicting recovery was 72% (95% confidence interval [CI] 60.9% to 81.3%), 67% (CI 55.8% to 77%) and 94% (CI 86.3% to 97.9%), respectively. The specificity of dipyridamole, dobutamine and combined dipyridamole-dobutamine was 95% (CI 86.7% to 99%), 92% (CI 82.4% to 97.3%) and 89% (CI 78.4% to 95.4%), respectively. The accuracy of the dobutamine, dipyridamole and combined dipyridamole-dobutamine test was 80%, 79% and 92%, respectively (combined dipyridamole-dobutamine vs. dobutamine, p < 0.05; combined dipyridamole-dobutamine vs. dipyridamole, p < 0.01).Conclusions. Infra-low dose dipyridamole added to low dose dobutamine recruits an inotropic reserve in asynergic segments that were nonresponders after either dobutamine or dipyridamole alone and destined to recover after revascularization.

Comparison of the diagnostic potential of four echocardiographic stress tests shortly after acute myocardial infarction: submaximal exercise, transesophageal atrial pacing, dipyridamole, and dobutamine-atropine

This study assessed and compared the diagnostic potential of submaximal exercise, transesophageal atrial pacing, dipyridamole, and dobutamine-atropine stress echocardiography tests shortly after acute myocardial infarction. In 121 study patients, 325 digital echocardiographic stress tests were attempted 10 to 11 days after acute myocardial infarction: 83 submaximal exercise tests, 121 high-dose dipyridamole echocardiography tests (DET), 69 transesophageal atrial pacing tests (< 150 beats/min), and 52 dobutamine tests, starting at 10 μg/kg per minute, increasing stepwise to 40 μg/ kg/min, and coadministering atropine in 12 patients (dobutamine-atropine stress echocardiography [DASE]). Results were correlated to a coronary artery diameter stenosis ≥50% as determined by quantitative angiography. Feasibility to perform submaximal exercise echocardiography, atrial pacing echocardiography, DET, and DASE was 89%, 52%, 98%, and 88%, respectively. Atrial pacing was not tolerated by 18 patients and refused by 6 (9%). Severe but not life-threatening side effects were hypotension in DET (2%) and tachyarrhythmias in DASE (6%). Test positivity in multivessel disease with submaximal exercise, DET, and DASE was 55%, 93%, and 90%, respectively, and in 1 -vessel disease 47%, 65%, 71%, and for atrial pacing, 82%, respectively. We conclude that submaximal exercise has limited sensitivity and atrial pacing limited feasibility. The pharmacologic stressors provide a useful, safe diagnostic approach: DET with slightly lower sensitivity in 1-vessel disease and DASE with insignificantly less feasibility.

Significance of transient ST-T segment changes during dobutamine testing in Q wave myocardial infarction

Objective. We evaluated dobutamine stress electrocardiography for detecting potentially reversible contractile dysfunction or residual ischemia in the infarct-related area.Background. ST-T segment changes in pathologic Q wave leads during stress testing may reflect contractile reserve, inducible ischemia or passive mechanical stretching. Dobutamine echocardiography allows detection of contractile reserve at low doses and inducible ischemia at high doses.Methods. We used low (5 to 10 μg/kg body weight per min) and high doses (20 to 40 μg/kg per min) of dobutamine in 49 patients with a previous Q wave myocardial infarction and analyzed the relation between ST-T segment changes in pathologic Q wave leads and regional contraction.Results. At low dose dobutamine, regional contraction improved in the infarct-related area in 23 patients. New or further ST segment elevation and pseudonormalization of negative T waves developed at low doses more frequently in patients with than without contractile reserve (both p < 0.001), giving a sensitivity of 43.5% and 60.9% and a specificity of 100% and 96.2%, respectively. At high dose dobutamine (43 patients), new or further ST segment elevation and pseudonormalization of negative T waves, occurring beyond those observed at low doses, lead a low predictive accuracy for contractile reserve (sensitivity of 9.5% and 14.3% and specificity of 68.2% and 81.8%, respectively). Pseudonormalization of negative T waves at high dose dobutamine was 100% specific (but only 25% sensitive) for homozonal ischemia.Conclusions. ST segment elevation or pseudonormalization of negative T waves, or both, is indicative of contractile reserve in the infarct-related area when either develops at low dose dobutamine, but may be associated with worsening or no change in contractile function at high doses.

Prognostic significance of low-dose dobutamine test in patients with advanced congestive heart failure due to dilated cardiomyopathy

Prognostic significance of low-dose dobutamine test in patients with advanced congestive heart failure due to dilated cardiomyopathy

986-77 Does Atropine Completely Abolish the Influence of β-blockade on the Ischemic Response During Dobutamine Stress Echocardiography?

To examine the effect of a β -blocker on the ischemic response to dobutamine stress and the degree to which this effect can be abolished by atropine, we produced in 7 pigs, using an hydraulic occluder, an LAD stenosis that reduced coronary flow (CF) reserve to 1.1 to 1.8 (maximal/resting flow), corresponding to a 50–80% diameter stenosis. Wall thickening was measured with epicardial echocardiography and sonomicrometers. Regional lactate production and coronary venous pH were monitored from the cardiac vein parallel to the LAD. A dobutamine infusion from 5 to 40 μ g/kg/min was given, with measurements made at each stage. After normalization of ischemic abnormalities, esmolol was infused at 50 μ g/kg/min, and the dobutamine test was repeated, with 1.0 mg of atropine added at the maximal dose. The β -blocker significantly altered the relationship between rate pressure product (RRP)/CF (an index of O 2 consumption and supply) and regional wall thickening (Figure). Esmolol prevented lactate production in 4/7 pigs and wall motion abnormalities in 3/7 pigs. Adding atropine induced lactate production and a reduction in wall thickening in all pigs. But lactate and regional venous pH were lower than without the β -blocker (p &lt; 0.05). In the presence of a β -blocker, adding atropine to dobutamine enhances the inducibility of myocardial ischemia, but does not completely reverse the effect of β -blockade.

Comparative ability of dobutamine and exercise stress in inducing myocardial ischaemia in active patients.

To compare the ability of dobutamine and exercise stress to induce myocardial ischaemia and perfusion heterogeneity under routine clinical circumstances. 86 active patients without previous myocardial infarction were studied by dobutamine and exercise stress protocols and coronary angiography. During both tests patients underwent electrocardiography, digitised echocardiography, and perfusion scintigraphy using Tc-99m methoxybutylisonitrile (MIBI) single photon emission computed tomography. Coronary disease defined as an ST segment depression of > or = 0.1 mV, a resting or stress induced perfusion defect, or a resting or stress induced wall motion abnormality on exercise and dobutamine stress testing. Dobutamine stress was submaximal in 51 patients because of ingestion of beta adrenoceptor blocking agents on the day of the test (n = 25) or failure to attain the peak dose owing to side effects (n = 28). Exercise was limited in 23 patients by non-cardiac symptoms. The peak heart rate with dobutamine was less than that attained with exercise (105 (25) v 132 (24) beats/min, P < 0.0001); the response to maximal dobutamine stress significantly exceeded that to submaximal stress. Peak blood pressure was greatest with exercise (206 (27) v 173 (25) mm Hg, P < 0.001), values at maximal and submaximal dobutamine stress being comparable. Electrocardiographic evidence of ischaemia was induced less frequently by dobutamine than exercise (32% v 77% of the 56 patients with significant coronary disease, P < 0.01), as was abnormal wall motion (54% v 88%, P < 0.001). Ischaemia was induced more readily with maximal stress of either type; thus the sensitivities of dobutamine and exercise echocardiography were comparable only in patients undergoing a maximal dobutamine testing (73% v 77%, NS). Perfusion heterogeneity was induced in 58% of patients with coronary disease at submaximal dobutamine stress, 73% at maximal dobutamine stress, and 73% at exercise stress (NS). Among 30 patients without coronary stenoses, normal function was obtained in 83% of echocardiography studies with dobutamine and in 80% with exercise (NS). Normal perfusion was identified in 70% of these patients at exercise MIBI, and 68% at dobutamine stress (NS). In a group of patients studied under normal clinical circumstances antianginal treatment and inability to complete the stress protocol are frequent and compromise the capacity of dobutamine stress to induce ischaemia. In contrast, the induction of perfusion heterogeneity is less susceptible to submaximal stress.