High Dose Dobutamine Infusion Research Articles

Childhood Cancer Survivors Have Impaired Strain-Derived Myocardial Contractile Reserve by Dobutamine Stress Echocardiography.

Abnormal left ventricular contractile reserve (LVCR) is associated with adverse cardiac outcomes in different patient cohorts and might be useful in the detection of cardiomyopathy in childhood cancer survivors (CCS) after cardiotoxic treatment. The aim of this study was to evaluate LVCR by dobutamine stress echocardiography (DSE) combined with measures of myocardial strain in CCS previously treated with anthracyclines (AC). Fifty-three CCS (age 25.34 ± 2.44 years, 35 male) and 53 healthy controls (age 24.40 ± 2.40 years, 32 male) were included. Subjects were examined with echocardiography at rest, at low-dose (5 micrograms/kg/min), and at high-dose (40 micrograms/kg/min) dobutamine infusion. Left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS), strain rate (GSR), and early diastolic strain rate (GEDSR) at different DSE phases were used as measures of LVCR. The mean follow-up time among CCS was 15.8 ± 5.8 years. GLS, GSR, and LVEF were lower at rest in CCS compared to controls (p ≤ 0.03). LVEF was within the normal range in CCS. ΔGLS, ΔGSR, and ΔGEDSR but not ΔLVEF were lower in CCS compared to controls after both low- (p ≤ 0.048) and high-dose dobutamine infusion (p ≤ 0.023). We conclude that strain measures during low-dose DSE detect impaired myocardial contractile reserve in young CCS treated with AC at 15-year follow-up. Thus, DSE may help identify asymptomatic CCS at risk for heart failure and allows for tailored follow-up accordingly.

Global Myocardial Contractile Reserve Assessed by High‐Dose Dobutamine Stress Echocardiography Predicts Response to the Cardiac Resynchronization Therapy

Myocardial contractile reserve (CR) is a strong prognostic factor in patients with heart failure. The presence of significant myocardial fibrosis can lead to a reduced response to cardiac resynchronization therapy (CRT). We assumed that myocardial CR assessed by high-dose dobutamine stress echocardiography (DSE) would predict response to CRT. Fifty-two consecutive symptomatic patients with heart failure (New York Heart Association [NYHA] class III), with depressed ejection fraction (EF) of the left ventricle (26.3 ± 6.9%) and dyssynchronous contractions (QRS duration 149.8 ± 23.8 msec) underwent DSE before CRT implantation. The difference in EF at rest and at peak (40 μg/kg per minute) DSE indicated global CR. Responders to CRT were defined by a decrease in left ventricular end-systolic volume of ≥15% and/or an increase in EF of ≥5% after 6 months of CRT. During high-dose dobutamine infusion, responders (28 patients, 54%) showed a greater increase in EF compared with nonresponders (Δ 11 ± 7% vs. Δ 2 ± 9%, P = 0.007). CR correlated moderately with an improvement in EF after 6 months of CRT (r = 0.50, P = 0.0009). Furthermore, responders showed significant improvement in clinical status, evaluated by a reduction in NYHA functional class (-0.8 ± 0.6 vs. 0.1 ± 0.4, P = 0.02), compared with nonresponders. A 7% exercise-induced increase in EF yielded sensitivity of 79% and specificity of 87% in predicting the response to CRT after 6 months. Myocardial CR assessed by high-dose DSE can play a potentially important role in identifying responders to CRT.

073 Right Ventricle Contractile Reserve as a Pre-operative Tool for Assessing RV failure after Continuous Flow LVAD Implantation

Latest generation continuous flow left ventricular assist devices (LVADs) have been proposed as an alternative to heart transplantation for end-stage heart failure. However, postoperative right ventricle (RV) dysfunction remains common and has a negative impact on prognosis. Purpose of our study was to identify echocardiographic or hemodynamic parameters that could predict early RV failure after LVAD implantation in patients with biventricular dysfunction. Fourteen patients with biventricular dysfunction who have been evaluated for LVAD implantation were included. Right and left ventricular dysfunction were respectively defined as: tricuspid annular plane excursion < 16 mm (TAPSE) and LV ejection fraction < 35%. In all patients, preoperative measurements were obtained at rest. In 7 patients, right heart catheterization was performed simultaneously with increasing doses of dobutamine (15γ/Kg/min). Primary endpoint was death caused by right ventricle systolic dysfunction or need for right ventricle mechanical support within 30 days after surgery (RVSD+). Mean recipient age was 58±7 years. Primary end-point (RVSD+) was noted in five patients. Preoperative demographic, echocardiographic and hemodynamic data were similar between RVSD+ and RVSD- patients (Table). Percent increase of TAPSE and systolic PAP between basal and high dobutamine dose was significantly lower in RVSD+ than in RVSD- patients. Percent increase of TAPSE and systolic PAP induced by high dose dobutamine infusion might be two interesting criteria to assess RV contractile reserve and predict RV outcome after LVAD implantation in patient with biventricular dysfunction. Baseline Measurement (n=14) Change after Dobutamine infusion,% (n=7) RVSD- RVSD+ p RVSD- RVSD+ p N 9 5 TAPSE, mm 14 ± 2 14 ± 2 0.9 55 ± 5 26 ± 2 0.03 Systolic PAP, mmHg 51 ± 7 53 ± 6 0.8 42 ± 8 4 ± 7 0.05 Cardiac Output, l/min 3.3 ± 0.5 3.5 ± 0.5 0.9 87 ± 10 93 ± 47 0.7 Pulm Vasc Res, Wood 3.9 ± 1 4.3 ± 1 0.6 2 ± 41 -36 ± 7 0.8

Evaluation of the anti-ischemic effects of D-ribose during dobutamine stress echocardiography: a pilot study

D-Ribose, a pentose sugar, has shown to improve myocardial high-energy phosphate stores depleted by ischemia. This study investigated the ability of D-Ribose with low dose dobutamine to improve the contractile response of viable myocardium to dobutamine and to assess the efficacy of D-ribose in reducing stress-induced ischemia. Twenty-six patients with ischemic cardiomyopathy completed a two-day, randomized, double blind crossover trial comparing the effects of D-Ribose and placebo on regional wall motion. On the first study day, either D-Ribose or placebo was infused for 4.5 hours. Low (5 and 10 μ/kg/min) and subsequently, high (up to 50 μ/kg/min) dose dobutamine echocardiography was then performed. On the second study day, patients crossed over to the alternative article for a similar 4.5 hours infusion time period and underwent a similar evaluation. The wall motion response during low dose dobutamine was the same with D-Ribose and placebo in 77% of segments (203/263, Kappa = 0.37). In segments with discordant responses, more segments improved with D-Ribose than with placebo (41 vs. 19 segments, p = 0.006). With high dose dobutamine infusion, the wall motion response (ischemia vs. no ischemia) was the same with D-Ribose and placebo in 83% of interpretable segments (301/363, kappa = 0.244). In segments with discordant responses, there were more ischemic segments with placebo compared to D-Ribose (36 vs. 26, p = 0.253). Nineteen patients developed ischemia during the dobutamine and placebo infusion and 13 patients had ischemia during dobutamine and D-ribose infusion (p = 0.109). D-Ribose improved contractile responses to dobutamine in viable myocardium with resting dysfunction but had no significant effect in reducing the frequency of stress-induced wall motion abnormalities.

Imaging the Physiology of the Ischemic Cascade

Stress cine function and vasodilating stress perfusion are commonly used approaches for the evaluation of ischemic heart disease. Both imaging approaches, using either stress echocardiography or stress nuclear scintigraphy, have stood the test of time as highly accurate in diagnosing coronary artery stenosis and as prognostic tools in patients with symptoms suspicious of myocardial ischemia.1,2 When epicardial coronary flow is interrupted and leads to an imbalance between myocardial oxygen supply and demand, reduced myocardial perfusion, regional ventricular dysfunction, and ECG change occur in quick succession; hence, the term “ischemic cascade” has been described.3 This phenomenon has been well described after acute balloon inflation during percutaneous coronary intervention and also during demand ischemia induced by dobutamine stress. Consequently, capturing abnormalities of both perfusion and function, in an attempt to improve the diagnostic performance of noninvasive tests, has been the focus of investigation using echocardiography and nuclear scintigraphy, with encouraging results.4–6 Article p 122 In this issue of Circulation: Cardiovascular Imaging , Gebker et al7 described the diagnostic utility of cardiac MRI (CMR) for evaluation of coronary artery disease using both myocardial perfusion (DSMRP) and function (DSMR) assessments during high-dose dobutamine stress testing. As shown in their work, CMR has technical features that are well suited for imaging both perfusion and regional function during a single, high-dose dobutamine infusion. With advances in imaging speed and algorithms of accelerated data reconstruction, gated cine steady-state free precession imaging can capture regional left ventricular dysfunction from ischemia at high temporal resolution and contrast-to-noise ratio. At target heart rates during peak stress, first-pass perfusion can sample myocardial …

Transient left ventricular apical ballooning during dobutamine myocardial perfusion imaging

The transient left ventricular apical ballooning is characterized by wall motion abnormalities involving the apex in the absence of obstructive coronary disease. It is precipitated by acute emotional or physical stress and is most often reported in post-menopausal women. We report a case of transient left ventricular “apical ballooning” without significant coronary artery disease precipitated by high dose dobutamine infusion during pharmacological stress myocardial perfusion imaging. The unique feature of our case was precipitation by chemical stress rather than emotional/physical stress.

211 Dobutamine stress echo: concordance between wall motion assessment and non-invasively evaluated coronary flow reserve

Aim: To assess consistency between left ventricular (LV) wall motion modification and coronary flow reserve in the left anterior descending coronary artery (LAD) territory during dobutamine stress-echo (DSE). Methods: 173 patients underwent DSE, according to the standard protocol, for evaluation of known or suspected coronary artery disease and, during the test, LAD flow velocity was measured at baseline and at peak stress. Segmental kinesis was evaluated both for all LV segments then limited to LAD territory (aWMSI). Coronary flow reserve (CFR) was calculated as the ratio between peak stress and baseline maximal diastolic velocity in the distal LAD. In a subgroup of 48 patients, without anterior myocardial infarction (MI), accuracy of non-invasively evaluated RFC was verified with coronary angiography data. Results: Patients were predominantly males (122.71%), mean age was 68±11 years; 69% were hypertensive, 37% diabetics, 46% presented dyslipidemia and 53% were smokers. Fifty-two patients had a recent or previous anterior MI, in 30 treated with primary PCI. Baseline echocardiography showed normal LV internal dimensions (end-diastolic volume index 63±20 ml/m 2 ; endsystolic volume index 34±18 ml/mq), with slightly reduced LV global systolic function (ejection fraction 47±27%). During ESD, both global WMSI then aWMSI resulted significantly and negatively correlated with RFC at baseline, after low dose and high dose dobutamine infusion; a similar correlation was also present between RFC and WMSI changes during high dose infusion, indicating extension of inducible ischemia. After exclusion of patients with anterior MI, these correlations remained significant; in the group with anterior MI, CFR was significantly and negatively correlated only with aWMSI after high dose infusion. Considering the final results of DSE and dividing patients in no or mild ischemia and extensive inducible ischemia (more than three LV segments), there was a significant difference in CFR value between the two groups (1.82 vs 2.26, p<0.001); otherwise presence or absence of viability didn’t influence CFR value. In absence of anterior MI, there was a good agreement between coronary angiography and noninvasively evaluated CFR (1.6 in patients with critical LAD stenosis vs 2.2 in patients with non critical lesions, p<0.05). Conclusion: LAD CFR evaluated during DSE demonstrates a good agreement with both LV segmental kinesis and coronary angiographic data, thus offering an adjunctive tool to improve DSE diagnostic accuracy.

Prognostic significance of sinus deceleration during dobutamine stress echocardiography test following acute myocardial infarction

Chronotropic incompetence during exercise stress testing after acute myocardial infarction is an indicator of ischemia or impaired left ventricular function. On the other side, infusion of dobutamine leads to a typical dose-dependent increase in heart rate. The aim of this study was to evaluate of paradoxical sinus deceleration during dobutamine stress echocardiography (DSE), as the sign of ischemia and impaired left ventricular function, or the consequence of infarction localization, and the estimation of prognostic significance after acute myocardial infarction. Our investigation comprised 81 patients hospitalized because of the acute myocardial infarction, and all of them had uncomplicated infarction. Fifty five patients were treated with thrombolytic therapy (67.9%); 53 patients (65.4%) had anterior myocardial infarction, and 28 patients (34.6%) had inferoposterior localization of myocardial infarction. After 10-12 days all of them underwent dobutamine stress echocardiography examination. During the next 3-6 months, the patients underwent coronary angiography. The average follow-up period was 36 +/- 22 months. A decrease in heart rate occurred at the dobutamine doses increasing from 15-40mcg/kg/min in 9 (11.1%) of the patients, in 1 patient with an anterior localization and in 8 patients with an inferoposterior localization. The decrease was sudden in 4 (44.4%), and gradual in 5 (55.6%) of the patients. In 3 patients (33.3%) junction rhythm was developed, and in 2 patients (22.2%) AV block II-III. Only in 2 of them, there was a worsening of regional function during a high dose dobutamine infusion, but 7 of them showed an improvement during a low dose. In 7 (77.8%) of the patients there was a simultaneous decrease in blood pressure. Coronary angiographic examination showed that in 4 (44.4%) of the patients there was a significant coronary artery disease and they underwent the revascularisation procedure. During the follow up period, there was not any significant arrhythmic disorder in that group of the patients or repeated hospitalization because of postinfarction angina, re-infarction, or heart failure. We could conclude that paradoxical sinus deceleration is not only an indicator of a significant coronary artery disease and "bad left ventricle". It also may occur as a consequence of vasodepressor reflex (Bezold-Jarisch), even after acute myocardial infarction, withont influencing a long-term prognosis.

Relationship between dobutamine response of dyssynergic myocardium and angiographically documented blood supply

Objective Because hibernation is considered a down-regulation of contractile function in response to reduced regional myocardial perfusion, hibernating myocardium is expected to be supplied by a critically stenosed or even occluded coronary artery. Thus, high-dose dobutamine has been postulated to cause ischemia and reworsening of myocardial function (biphasic response), whereas myocardium that demonstrates sustained improvement with high-dose dobutamine should not be supplied by a significantly stenosed vessel. This study evaluates the type of dobutamine response–biphasic versus sustained improvement–of dyssynergic myocardium in relation to its angiographically documented blood supply. Methods In 38 patients (5 women; mean age 60 ± 9 years) with chronic coronary artery disease and impaired left ventricular ejection fraction (≤35%), dobutamine echocardiography and quantitative coronary angiography were performed within 4 weeks. Wall-motion response of dyssynergic myocardium to dobutamine, classified as no improvement, biphasic response, or sustained improvement, was comparedwith the angiographically documented blood supply (presence of coronary stenosis in the corresponding artery, collaterals, and stenoses of the collateral supplying artery) in a segment-by-segment analysis. Results Of the 465 segments with abnormal wall motion at rest, 201 (47%) showed improvement during dobutamine infusion at low dose. Of these, 145 (72%) were supplied by significantly stenosed epicardial vessels. Only 27 (19%) of these 145 segments showed a biphasic response whereas in the remaining 118 segments wall-motion improvement persisted during high-dose dobutamine infusion. Although mean stenosis severity in the supplying vessel was significantly greater for segments presenting with biphasic response as compared with sustained improvement (95 ± 7% and 86 ± 12% luminal diameter reduction, respectively; P < .0001), 69% of segments with sustained improvement were supplied by a critically stenosed artery. Only 7 of 27 segments with biphasic response and 22 of 118 segments with sustained improvement had visible collaterals supplied by a vessel without significant stenosis. The percentage of segments viable by thallium-single photon emission computed tomography imaging was similar for those with sustained and biphasic response (96% and 83%, respectively). Conclusions In this group of patients with coronary artery disease and impaired left ventricular function, the great majority of dyssynergic segments that exhibited a sustained, rather than biphasic, dobutamine response were supplied by a critically stenosed artery. Furthermore, the percentage of segments viable by thallium-single photon emission computed tomography did not appear to be different for segments with sustained improvement and those with biphasic response. These findings challenge the hypothesis that biphasic response is the best criterion to identify viable myocardium.

Doppler indices of diastolic transmitral flow velocity are invalid indicators of myocardial ischaemia during high-dose dobutamine infusion in anaesthetized patients

Background and objective: Doppler echocardiography of diastolic transmitral flow velocity is more sensitive for the detection of myocardial ischaemia in awake patients than echocardiographic analysis of systolic wall motion. However, its diagnostic value in anaesthetized patients is unknown. Methods: Doppler indices of diastolic transmitral flow velocity previously found to be highly sensitive for detecting ischaemia in awake patients were studied in 72 anaesthetized patients with documented coronary artery disease undergoing dobutamine stress echocardiography. These Doppler indices were compared with standard echocardiographic and electrocardiographic criteria for ischaemia. Results: Sixty-five patients showed evidence of ischaemia by standard echocardiographic and/or electrocardiographic criteria, and seven patients did not. Regardless of evidence of ischaemia by standard criteria, the Doppler indices changed similarly in both groups. Accordingly, only a minority of anaesthetized patients displayed the changes in Doppler indices of diastolic transmitral flow previously suggested to be sensitive for detecting ischaemia. Conclusions: The results do not confirm the diagnostic value of Doppler echocardiography of diastolic transmitral flow velocity for detecting ischaemia in anaesthetized patients undergoing dobutamine stress echocardiography during positive-pressure ventilation of the lungs.

Doppler indices of diastolic transmitral flow velocity are invalid indicators of myocardial ischaemia during high-dose dobutamine infusion in anaesthetized patients.

Doppler echocardiography of diastolic transmitral flow velocity is more sensitive for the detection of myocardial ischaemia in awake patients than echocardiographic analysis of systolic wall motion. However, its diagnostic value in anaesthetized patients is unknown. Doppler indices of diastolic transmitral flow velocity previously found to be highly sensitive for detecting ischaemia in awake patients were studied in 72 anaesthetized patients with documented coronary artery disease undergoing dobutamine stress echocardiography. These Doppler indices were compared with standard echocardiographic and electrocardiographic criteria for ischaemia. Sixty-five patients showed evidence of ischaemia by standard echocardiographic and/or electrocardiographic criteria, and seven patients did not. Regardless of evidence of ischaemia by standard criteria, the Doppler indices changed similarly in both groups. Accordingly, only a minority of anaesthetized patients displayed the changes in Doppler indices of diastolic transmitral flow previously suggested to be sensitive for detecting ischaemia. The results do not confirm the diagnostic value of Doppler echocardiography of diastolic transmitral flow velocity for detecting ischaemia in anaesthetized patients undergoing dobutamine stress echocardiography during positive-pressure ventilation of the lungs.

Usefulness of rest and low-dose dobutamine wall motion scores in predicting survival and benefit from revascularization in patients with ischemic cardiomyopathy

This study examined the value of wall motion scores at rest and with low- and high-dose dobutamine infusion for prediction of outcome and benefit from revascularization in patients with ischemic cardiomyopathy. Follow-up was obtained in 139 patients with ischemic cardiomyopathy who had echocardiography at rest, and during low- (10 μg/kg/min) and high-dose dobutamine (maximal dose 50 μg/kg/min) infusion. Both rest and low-dose wall motion scores were multivariate predictors of cardiac death, but ischemia and peak dose scores were not predictors. Rest scores risk stratified patients into 3 groups: score (1.00 to 1.99) with 11% cardiac death; score (2.00 to 2.49) with 30% death; and score ≥2.50 with 47% death. One third of patients with rest scores ≥2.50 had improvement in scores to <2.50 with low-dose dobutamine. Their frequency of cardiac death was reduced to 23% compared with 60% (p = 0.04) in those who remained with low-dose scores ≥2.50. Low-dose scores also identified those who benefited from revascularization. In patients with low-dose scores (1.00 to 1.99), the frequency of cardiac death was marginally lower in revascularized than nonrevascularized patients (10% vs 21%, p = 0.28). In patients with scores (2.00 to 2.49), revascularized patients had a significantly lower frequency of cardiac death than nonrevascularized patients (15% vs 41%, p <0.05). The frequency of death in those with low-dose scores ≥2.50 was very high in both revascularized (75%) and nonrevascularized (56%, p = 0.42) patients. Thus, rest and low-dose wall motion scores enable risk stratification of patients with ischemic cardiomyopathy and identify those who do and do not benefit from revascularization.

Significance of dobutamine-induced changes in QT dispersion early after acute myocardial infarction

This study sought to examine the effects of graded dobutamine infusion on QT dispersion early after acute myocardial infarction (AMI) and to investigate the relation of dobutamine-induced changes in QT dispersion to wall motion responses. Seventy-eight patients with a first AMI underwent dobutamine-atropine stress echocardiography 5 ± 2 days after admission. Contractile reserve was identified in 45 patients and ischemic myocardium in 40. Sixteen patients had persistent akinesia. The best cut-off value of QT dispersion on the baseline electrocardiogram for predicting myocardial viability was 65 ms (sensitivity and specificity of 68%). Dobutamine infusion increased QT dispersion only in patients with viable myocardium (61 ± 18 to 83 ± 19 ms, p = 0.003) and/or ischemia (72 ± 16 to 112 ± 25 ms, p <0.0001). No change was observed in patients with persistent akinesia (84 ± 10 to 87 ± 15 ms, p = NS). QT dispersion increased by 22 ± 12 ms with administration of low-dose dobutamine in patients who had viable myocardium and by 47 ± 21 ms with administration of low- to high-dose dobutamine in patients with ischemic myocardium. An increase in QT dispersion of ≥20 ms from at rest to low-dose dobutamine infusion was associated with myocardial viability with a sensitivity of 78% and a specificity of 79%, whereas an increase in QT dispersion of ≥10 ms from low- to high-dose dobutamine infusion predicted ischemic myocardium with a sensitivity of 85% and a specificity of 82%. In conclusion, (1) low QT dispersion on the baseline electrocardiogram is determined by the presence of viable myocardium, (2) a dobutamine-induced increase in QT dispersion is associated with viable and jeopardized myocardium, and (3) unchanged QT dispersion during dobutamine stress is a simple marker of extensive necrosis.

Ultrasonic tissue characterization with integrated backscatter during inotropic stimulation

Ultrasonic tissue characterization with integrated backscatter is an objective method to quantitatively define the physical state of the myocardium. To determine if backscatter imaging during inotropic stimulation could be used objectively to determine the myocardial viability and ischemia in patients with ischemic heart disease, the backscatter changes were examined in 23 patients with myocardial infarction during dobutamine stress two-dimensional (2-D) echocardiography. Coronary angiography was performed within 1 to 2 days after the stress test. The results of this study demonstrated that changes in backscatter variability correlated significantly with the wall motion changes in stress echocardiography during dobutamine infusion ( p < 0.0001). In addition, it was shown that the backscatter changes were significantly different in various types of myocardial tissue. In 23 healthy control segments, the ultrasonic backscatter variability was preserved and unchanged during inotropic stimulation ( p = NS). In 15 viable infarct zones, restoration or an increase in backscatter variability during low-dose dobutamine infusion was noted, this being lost when ischemia developing during high-dose dobutamine infusion ( p < 0.01). In 9 nonviable infarct zones, the phase-weighted variation was usually ≤ 0 and did not change significantly during inotropic stimulation, regardless of the patency of the infarct-related arteries. In 15 remote ischemic myocardial zones, the backscatter variability was preserved at the baseline level, did not change during low-dose dobutamine infusion, but decreased significantly during high-dose dobutamine stress ( p < 0.01). In conclusion, dobutamine stress tissue characterization could offer an objective approach for the detection of myocardial viability and ischemia, and might be a useful adjunct to the conventional stress echocardiography.

Myocardial Perfusion and Angiographic Findings in Patients with Paradoxical Sinus Deceleration during Dobutamine Technetium-99m Sestamibi-Gated SPECT Imaging

Aims: Dobutamine-gated SPECT imaging allows simultaneous perfusion and function assessment and is an alternative stress method for evaluating coronary artery disease in patients unable to perform treadmill exercise. In some patients, a paradoxical decrease in heart rate has been observed during high dose dobutamine infusion. The purpose of this study was to describe the paradoxical decrease in heart rate observed during dobutamine perfusion scintigraphy and determine its relation to inducible ischemia and angiographic coronary artery disease. Methods and Results: We studied 52 patients who underwent dobutamine-gated ^99mTc sestamibi SPECT imaging and coronary angiography within 30 days. Paradoxical deceleration was defined as a decrease in heart rate ≥5 beats/min lasting at least 3 min during dobutamine infusion. Perfusion was graded on a five-point scale (0 = normal; 4 = absent uptake) and wall motion on a four-point scale (0 = akinesia/dyskinesia; 3 = normal) using the 20-segment model. Significant coronary artery disease was defined as ≥50% narrowing of lumen diameter of a major epicardial artery. Paradoxical deceleration occurred in 10 patients (19%, 95% CI 8–30%). A decrease in systolic blood pressure [8 patients (80%), 95% CI 56–92%] with angina [5 patients (50%), 95% CI 23–71%] often accompanied the decrease in heart rate. All 10 patients with sinus deceleration had an inferior wall perfusion defect and 8 of them had a corresponding wall motion abnormality on gated images. Significant coronary artery disease was present in all 10 patients with sinus deceleration, with an increased incidence of right coronary artery stenosis (p = 0.007). Conclusions: Paradoxical deceleration observed during dobutamine perfusion scintigraphy is associated with inducible ischemia and angiographic coronary artery disease and the underlying mechanism for this phenomenon may be the activation of the Bezold-Jarisch reflex.

Diagnostic criteria for detection of postinfarction ischemia by quantitative analysis of stepwise dobutamine radionuclide ventriculography

Background: Application of the traditional diagnostic criteria validated for exercise testing may be inappropriate when dobutamine infusion is associated with radionuclide ventriculography (RNV). The objective of this study was to establish appropriate diagnostic criteria for evaluation of dobutamine stress testing with RNV for the detection of early postinfarction ischemia. Methods: RNV was performed at baseline and during dobutamine infusion in 10 control subjects and in 30 patients who were studied within 1 week after uncomplicated myocardial infarction. Several quantitative parameters including left ventricular ejection fraction (EF), regional EF, and absolute change in global and regional EF were tested. In addition, regional wall-motion changes were scored by visual analysis. The limit of normal response for each quantitative parameter was defined as the 95th percentile of the distribution observed in control subjects. On the basis of predischarge clinical evaluation and exercise stress testing, patients were grouped as having evidence of residual ischemia (group 1, 15 patients) or no evidence of ischemia (group 2, 15 patients). Sensitivity, specificity, and accuracy in the detection of postinfarction ischemia were calculated for each parameter, and empiric receiver-operating characteristic curves were generated. Results: The limits of the normal response to dobutamine infusion in the control subjects were found to be a 7.5% and a 12.5% increase in global EF at low and high dose, respectively. Median baseline EF was significantly lower in patients than in control subjects (Mann-Whitney U test: P < .001). There were no differences in resting EF between group 1 and group 2 patients. However, median high-dose EF and increase in EF were significantly lower in group 1 as compared with group 2 patients (56% vs 72% and 5% vs 17%, respectively; Mann-Whitney U test: P < .0001 for both). A biphasic (up-and-down) response with initial increase at low dose followed by decrease or no change in EF at high dose was observed in 66% of group 1 patients and only in 13% of group 2 subjects. The best criterion for detection of postinfarction ischemia was a change of <12.5% in global EF at high-dose dobutamine infusion, with 80% predictive accuracy. The traditional criterion, a change of <5% or a decrease in EF, yielded an accuracy of only 63%. The association of a change of <12.5% with a biphasic response increased accuracy to 87%, with a sensitivity of 93% and a specificity of 80%. Quantitative regional wall motion analysis showed greater diagnostic accuracy than visual wall motion scoring (83% vs 70%). Conclusions: Application of appropriate criteria and stepwise quantitative analysis of RNV during dobutamine infusion may increase accuracy in the detection of early postinfarction ischemia.

Paradoxical Sinus Deceleration During Dobutamine Stress Echocardiography: Description and Angiographic Correlation

Objectives. This report characterizes the paradoxical sinus deceleration occasionally observed during dobutamine stress testing and determines its relation to myocardial ischemia.Background. Dobutamine stress echocardiography is widely accepted as a noninvasive tool for evaluating coronary artery disease. With infusion of dobutamine, there is typically a dose-dependent increase in heart rate. However, in some patients, a paradoxical decrease in heart rate has been observed during high dose dobutamine infusion.Methods. In 181 consecutive patients undergoing both dobutamine stress echocardiography and coronary angiography, electrocardiographic (ECG) data collected during dobutamine infusion were reviewed to identify patients with a decrease in heart rate. The clinical, stress echocardiographic, hemodynamic and angiographic correlates of patients with a decrease in heart rate were reviewed.Results. A decrease in heart rate ranging from 7 to 64 beats/min occurred during high dose dobutamine infusion in 14 patients (8%, 95% confidence interval [CI] 6% to 10%), including 3 in whom a junctional rhythm developed. The decrease was sudden in five patients (36%, 95% CI 13% to 65%) and gradual in nine (64%, 95% CI 35% to 87%). A decrease in blood pressure (12 patients [86%], 95% CI 57% to 98%) with simultaneous chest pain (7 patients [50%], 95% CI 23% to 77%) and nausea (5 patients [36%], 95% CI 13% to 65%) was common. Significant coronary artery disease (≥50% diameter stenosis) was present in 8 (57%) of 14 patients (95% CI 29% to 82%). Two patients (14%, 95% CI 2% to 43%) had no clinical, ECG or echocardiographic evidence of ischemia and no significant coronary artery disease by angiography. There was no increased incidence of right coronary artery stenosis in patients with paradoxical sinus deceleration.Conclusions. Paradoxical sinus deceleration occurs in 8% of patients during dobutamine stress testing. Although most often observed in patients with coronary artery disease, it can occur in the absence of ischemia and coronary artery disease, and in some patients may be due to a vasodepressor reflex.(J Am Coll Cardiol 1997;29:994–9)© 1997 by the American College of Cardiology

Enhanced detection of myocardial ischemia by stress dobutamine echocardiography utilizing the “biphasic” response of wall thickening during low and high dose dobutamine infusion: R. Senior, A. Lahiri. Department of Cardiology, Northwick Park Hospital, Harrow, Middlesex, Great Britain. J Am Coll Cardiol 1995:26:26–32

Enhanced detection of myocardial ischemia by stress dobutamine echocardiography utilizing the “biphasic” response of wall thickening during low and high dose dobutamine infusion: R. Senior, A. Lahiri. Department of Cardiology, Northwick Park Hospital, Harrow, Middlesex, Great Britain. J Am Coll Cardiol 1995:26:26–32

Enhanced detection of myocardial ischemia by stress dobutamine echocardiography utilizing the “biphasic” response of wall thickening during low and high dose dobutamine infusion

We sought to assess the ability of the "biphasic" response (i.e., initial improvement in wall thickening followed by reduced wall thickening) during serial dobutamine stress echocardiography to detect ischemia in patients with a wall motion abnormality. Furthermore, we compared the power of the biphasic echocardiographic response with that of myocardial perfusion imaging for the detection of myocardial ischemia. Stress echocardiography has been shown to be less sensitive than radionuclide perfusion imaging for detecting ischemia in patients with a wall motion abnormality. Peak stress wall thickening in such areas may not give a full account of the intermediate changes, whereas initial improvement (the biphasic response) may enhance diagnosis. Patients with a wall motion abnormality and documented coronary artery disease underwent simultaneous graded dobutamine (5 to 40 micrograms/kg body weight per min) stress echocardiography and radionuclide perfusion imaging with single-photon emission computed tomography using either technetium-99m sestamibi or technetium-99m tetrofosmin. Semiquantitative analyses of image groups were performed in blinded manner by two separate groups of observers. Myocardial ischemia was detected by perfusion imaging in 45 of the 54 patients. High dose dobutamine echocardiography detected ischemia in only 25 (56%) of these patients. However, when the biphasic response was taken into account, ischemia was detected in 44 (98%) of the 45 patients (p < 0.001). Agreement between radionuclide imaging and echocardiographic findings for the detection of ischemia was significantly enhanced (p = 0.03) when the biphasic response was used (89%, kappa = 0.51) instead of high dose stress dobutamine echocardiography (56%, kappa = 0.10). The detection of myocardial ischemia may be significantly enhanced by utilizing the biphasic response during serial stress dobutamine echocardiography in patients with a wall motion abnormality.

Normal changes in left ventricular filling and hemodynamics during dobutamine stress echocardiography

During high-dose dobutamine infusion, there is a dose-dependent increase in cardiac output, a reduction in systemic vascular resistance, a reduction in left ventricular size, an increase in the mitral A wave velocity, a reduction in the E/A velocity ratio, and a reduction in the isovolumic relaxation time, with little change in the rate-corrected isovolumic relaxation time. Left ventricular cavity obliteration is common. This information may be useful in defining the mechanism of hypotension commonly seen during dobutamine stress echocardiography. It is speculated that the diastolic behavior of the left ventricle during dobutamine stress echocardiography, especially the isovolumic relaxation time, may provide an additional indicator of early myocardial ischemia, but this needs to be confirmed by larger independent studies.