Myocardial viability on echocardiography predicts long-term survival after revascularization in patients with ischemic congestive heart failure.
(17/1123)
OBJECTIVES: This study was conducted to evaluate the effect of revascularization on survival in patients with congestive heart failure (CHF) due to ischemic left ventricular (LV) systolic dysfunction based on the presence of myocardial viability (MV). BACKGROUND: There are insufficient data regarding the survival benefit of revascularization in patients with CHF due to ischemic LV systolic dysfunction. METHODS: Follow-up was obtained in 87 consecutive patients with CHF due to ischemic LV systolic dysfunction (New York Heart Association [NYHA] class II-IV; LV ejection fraction <0.35) who underwent low-dose dobutamine echocardiography (DE). MV within each of 12 myocardial segments representing the LV was defined as having either: 1) normal function or mild dyssynergy at rest; 2) severe resting dyssynergy that improved on DE, or 3) worsening of function on DE except in the case of akinesia. RESULTS: At a mean follow-up of 40+/-17 months, 37 patients had received revascularization on the basis of clinical grounds, and there were 22 (25%) cardiac-related deaths. Multivariate Cox regression analysis revealed that when patients with at least five segments showing MV underwent revascularization, mortality was reduced by an average of 93% (confidence interval of 22% to 99%), which was associated with improvement in NYHA class as well as LV ejection fraction. Patients with less than five segments showing MV who underwent revascularization (and thus, showing mostly scar), and those with at least 5 segments demonstrating MV who were treated medically, had a much higher mortality. CONCLUSIONS: Revascularization produces a clear survival benefit in patients with CHF due to ischemic LV systolic dysfunction who have a significant region of the LV demonstrating MV. These data may have wide-ranging implications in the management of patients with coronary artery disease whose main clinical presentation is CHF. (+info)
The significance of stress-induced ST segment depression in patients with inferior Q wave myocardial infarction.
(18/1123)
OBJECTIVES: This study was conducted to evaluate the relationship between ST segment depression (STD) during dobutamine stress tests in different electrocardiogram (ECG) leads and myocardial ischemia assessed by simultaneous single photon emission computed tomography (SPECT) imaging in patients with inferior Q wave myocardial infarction. BACKGROUND: STD is a standard electrocardiographic sign of myocardial ischemia. Although STD may represent reciprocal changes in patients with previous myocardial infarction, studies of reciprocal changes during stress tests are scarce. METHODS: Dobutamine (up to 40 microg/kg/min) stress and rest myocardial perfusion scintigraphy using technetium SPECT imaging was performed in 125 patients >3 months after Q wave inferior myocardial infarction. The location of STD at the ECG was defined as anterior (V1-4), high lateral (I, aVL) and lateral (V5,6). Ischemia was defined as reversible perfusion abnormalities. RESULTS: STD occurred in the high lateral leads in 20 patients, in the anterior leads in 12 patients and in the lateral leads in 2 patients. ST segment elevation occurred in 25 patients in the inferior leads. High lateral STD was associated with inferior ST elevation in 16 patients (80%). There was a significant inverse linear correlation between the magnitude of ST segment shift from rest to peak stress in the inferior and the high lateral leads (r = -0.8, p < 0.0005), whereas no significant correlation was found between ST segment shift in the inferior and the anterior leads (r = -0.1, p = NS) or between the inferior and the lateral leads (r = 0.15, p = NS). Ischemia was detected in 45% of patients with and in 42% of patients without high lateral STD (p = NS). Patients with high lateral STD had a higher prevalence of fixed perfusion defects in the inferior wall (100% vs. 70%) and in the posterolateral wall (55% vs. 29%) compared with other patients (both p < 0.05). Ischemia was more prevalent in patients with anterior STD than without (75% vs. 39%, p < 0.05). CONCLUSIONS: In patients with inferior Q wave myocardial infarction, stress-induced STD in high lateral leads should be recognized as a reciprocal change for ST elevation in the inferior leads, and therefore, should be interpreted with the consideration of the significance of ST elevation if present, rather than being indicative of myocardial ischemia on its own. The STD found in the anterior leads appears to be a sign of myocardial ischemia. These findings should be considered in the definition of a positive ECG stress test and in establishing the criteria for the termination of stress test. (+info)
The relation between transaortic pressure difference and flow during dobutamine stress echocardiography in patients with aortic stenosis.
(19/1123)
OBJECTIVE: To investigate the relation between transaortic pressure difference and flow in patients with aortic stenosis. METHODS: 50 asymptomatic patients with all grades of aortic stenosis were studied using dobutamine stress echocardiography. Individual plots of mean pressure drop against flow were drawn. Comparisons were made between grades of aortic stenosis as defined by the continuity equation. RESULTS: A significant linear relation between pressure difference and flow was found in 34 patients (68%). There was a significant curvilinear relation in four (8%), while no significant regression line could be fitted in 12 (24%). In the 34 patients with linear fits, the slopes (mean (SD)) were 0.08 (0.07) in mild, 0.10 (0.04) in moderate, and 0.22 (0.16) in severe aortic stenosis (p = 0. 0055). CONCLUSIONS: Transaortic pressure difference can be related directly to flow in many patients with all grades of aortic stenosis. However, there are individual differences in slope and intercept suggesting that resistance calculated at rest may not always be representative. Raw pressure drop/flow plots may be an alternative method of describing valve function. (+info)
Combined assessment of reflow and collateral blood flow by myocardial contrast echocardiography after acute reperfused myocardial infarction.
(20/1123)
OBJECTIVE: To evaluate the combined assessment of reflow and collateral blood flow by myocardial contrast echocardiography after myocardial infarction. DESIGN: Myocardial contrast echocardiography was performed in patients with acute myocardial infarction shortly after successful coronary reperfusion (TIMI 3 patency) by direct angioplasty. Collateral flow was assessed before coronary angioplasty, and contrast reflow was evaluated 15 minutes after reperfusion. The presence of contractile reserve was assessed by low dose dobutamine echocardiography (5 to 15 micrograms/kg/min) at (mean (SD)) 3 (2) days after myocardial infarction. Recovery of segmental function (myocardial viability) was evaluated by resting echocardiography at a two month follow up. The study was prospective. PATIENTS: 35 consecutive patients referred for acute transmural myocardial infarction. RESULTS: Contrast reflow was observed in 20 patients (57%) and collateral flow in 14 (40%). Contrast reflow and collateral contrast flow were both correlated with reversible dysfunction on initial dobutamine echocardiography and at follow up (p < 0.05). The presence of reflow or collateral flow on myocardial contrast echocardiography was a highly sensitive (100%) but weakly specific (60%) indicator of segmental dysfunction recovery. Simultaneous presence of contrast reflow and collateral flow was more specific of reversible dysfunction than reflow alone (90% v 60%). CONCLUSIONS: Combined assessment of reflow and collateral blood flow enhanced the sensitivity of myocardial contrast echocardiography in predicting myocardial viability after acute, reperfused myocardial infarction. The simultaneous presence of reflow and collateral blood flow was highly specific of recovery of segmental dysfunction. (+info)
Negative chronotropic effects of fentanyl attenuate beneficial effects of dobutamine on oxygen metabolism: hemodynamic and pharmacokinetic interactions.
(21/1123)
Opioids are well known to cause cardiovascular depression. The aim of the present investigation was to determine whether an interaction of opioid derivatives with catecholamines might be involved in these hemodynamic alterations. Six comatose patients were enrolled into a prospective, nonrandomized pilot trial. All patients first received a continuous i.v. infusion of dobutamine (10 microgram. kg-1. min-1) paralleled by continuous administration of midazolam (0.4 mg. kg-1. h-1); thereafter, fentanyl was added i.v. (4 microgram. kg-1. h-1). Hemodynamic parameters as well as dobutamine and endogenous catecholamines plasma levels were determined. The mean arterial blood pressure did not change significantly during the whole study period. The continuous administration of dobutamine (steady-state plasma concentrations: 217 +/- 118 ng. ml-1) increased the beta1-adrenergic receptor-mediated hemodynamic parameters such as heart rate, stroke volume index, cardiac index, and oxygen delivery index (p <.05). The concomitant administration of fentanyl decreased the heart rate-dependent hemodynamic parameters (p <.05), suggesting that fentanyl antagonizes the chronotropic effects of dobutamine. In parallel, dobutamine plasma levels increased significantly (275 +/- 165 ng. ml-1; p <.05). Noteworthy, after administration of fentanyl, oxygen delivery and consumption index returned to baseline values. Radioligand binding experiments on rat cardiac ventricular microsomes ruled out a direct interaction of fentanyl with beta-adrenergic receptors and, more importantly, a fentanyl-induced inhibition of beta-adrenergic receptor G protein coupling. Our observations suggest that fentanyl inhibits the frequency-related hemodynamic changes induced by dobutamine. The underlying mechanism is independent of beta-adrenergic receptors, but is powerful enough to abolish the salutary effect of dobutamine on oxygen delivery and consumption. (+info)
Improvement of left ventricular ejection fraction, heart failure symptoms and prognosis after revascularization in patients with chronic coronary artery disease and viable myocardium detected by dobutamine stress echocardiography.
(22/1123)
OBJECTIVES: This study was designed to address, in patients with severe ischemic left ventricular dysfunction, whether dobutamine stress echocardiography (DSE) can predict improvement of left ventricular ejection fraction (LVEF), functional status and long-term prognosis after revascularization. BACKGROUND: Dobutamine stress echocardiography can predict improvement of wall motion after revascularization. The relation between viability, improvement of function, improvement of heart failure symptoms and long-term prognosis has not been studied. METHODS: We studied 68 patients with DSE before revascularization; 62 patients underwent resting echocardiography/radionuclide ventriculography before and three months after revascularization. Long-term follow-up data (New York Heart Association [NYHA] functional class, Canadian Cardiovascular Society [CCS] classification and events) were acquired up to two years. RESULTS: Patients with > or =4 viable segments on DSE (group A, n = 22) improved in LVEF at three months (from 27+/-6% to 33+/-7%, p < 0.01), in NYHA functional class (from 3.2+/-0.7 to 1.6+/-0.5, p < 0.01) and in CCS classification (from 2.9+/-0.3 to 1.2+/-0.4, p < 0.01); in patients with <4 viable segments (group B, n = 40) LVEF and NYHA functional class did not improve, whereas CCS classification improved significantly (from 3.0+/-0.8 to 1.3+/-0.5, p < 0.01). A higher event rate was observed at long-term follow-up in group B versus group A (47% vs. 17%, p < 0.05). CONCLUSIONS: Patients with substantial viability on DSE demonstrated improvement in LVEF and NYHA functional class after revascularization; viability was also associated with a favorable prognosis after revascularization. (+info)
Levosimendan: effects of a calcium sensitizer on function and arrhythmias and cyclic nucleotide levels during ischemia/reperfusion in the Langendorff-perfused guinea pig heart.
(23/1123)
The majority of clinically used inotropes act by increasing cytosolic calcium levels, which may hypothetically worsen reperfusion stunning and provoke arrhythmias. We tested the hypothesis that the calcium sensitizer levosimendan (levo) given during ischemia alone or ischemia and reperfusion would improve reperfusion function without promoting arrhythmias. The Langendorff-perfused guinea pig heart, subjected to 40-min low-flow ischemia (0.4 ml/min) with or without levo (10-300 nM) given during ischemia or ischemia/reperfusion was used. Left ventricular developed pressure (LVDP) was used as an index of mechanical function. The effect of levo (300 nM) or dobutamine (0.1 microM) on the incidence of ischemia/reperfusion arrhythmias was also investigated. Control hearts (vehicle-perfused) had LVDPs of 69.4 +/- 2.1 mm Hg whereas hearts treated with levo during ischemia and reperfusion (300 nM) had LVDPs of 104.5 +/- 2.7 mm Hg (p <.05). Hearts treated with levo during ischemia alone (10 nM) had reperfusion LVDPs of 95.8 +/- 4.2 mm Hg (p <.05) after 30-min reperfusion. Hearts treated with both levo and 10 microM glibenclamide (K(ATP) channel blocker) during ischemia had reperfusion LVDPs of 73.4 +/- 4.3 mm Hg after 30-min reperfusion. Of control hearts, 25% developed reperfusion ventricular tachycardia but not ventricular fibrillation. Levo-treated hearts had no ischemia/reperfusion arrhythmias whereas 83% (p <.05 versus control) of dobutamine-treated hearts developed ventricular tachycardia and 33% (p <.05 versus levo) developed reperfusion ventricular fibrillation. Levo improved reperfusion function without promoting arrhythmias in this model. This was possibly achieved by opening the K(ATP) channels during ischemia and sensitizing myocardial contractile apparatus instead of elevating cytosolic calcium levels in reperfused hearts. (+info)
Effects of dobutamine on coronary stenosis physiology and morphology: comparison with intracoronary adenosine.
(24/1123)
BACKGROUND: The mechanisms leading to dobutamine-induced ischemia are not fully understood. In the present study, we investigated the effects of high-dose intravenous dobutamine on morphological and physiological indexes of coronary stenoses. METHODS AND RESULTS: Twenty-two patients with normal left ventricular function and isolated coronary stenoses were studied. At catheterization, mean aortic pressure (P(a)), mean distal coronary pressure (P(d)), and P(d)/P(a) as an index of myocardial resistance were recorded at rest, after intracoronary adenosine, and during intravenous infusion of dobutamine (10 to 40 micrograms . kg(-1). min(-1)). Reference vessel diameter and minimal luminal diameter, as assessed by coronary angiography, did not change during dobutamine infusion compared with baseline (2.84+/-0.49 versus 2.77+/-0.41 mm and 1.35+/-0.38 versus 1. 27+/-0.31 mm, respectively; both P=NS). During peak dobutamine infusion, P(d) and P(d)/P(a) reached similar levels as during adenosine infusion (60+/-18 versus 59+/-18 mm Hg and 0.68+/-0.18 versus 0.68+/-0.17, respectively; all P=NS). In 9 patients, an additional bolus of intracoronary adenosine given at the peak dose of dobutamine failed to further decrease P(d)/P(a). Furthermore, in patients with dobutamine-induced wall motion abnormalities, the maximal decrease in P(d)/P(a) was similar during dobutamine and adenosine infusions. CONCLUSIONS: High-dose intravenous infusion of dobutamine does not modify the dimensions of the epicardial coronary stenosis. However, much like the direct coronary vasodilator adenosine, dobutamine fully exhausts myocardial resistance regardless of the presence of mechanical dysfunction. (+info)