Recovery of contractility of viable myocardium during inotropic stimulation is not dependent on an increase of myocardial blood flow in the absence of collateral filling.
(17/9635)
OBJECTIVES: The purpose of this study was to determine whether contractile recovery induced by dobutamine in dysfunctioning viable myocardium supplied by nearly occluded vessels is related to an increase in blood flow in the absence of collaterals. BACKGROUND: Dobutamine is used to improve contractility in ventricular dysfunction during acute myocardial infarction. However, it is unclear whether a significant increase in regional blood flow may be involved in dobutamine effect. METHODS: Twenty patients with 5- to 10-day old anterior infarction and > or =90% left anterior descending coronary artery stenosis underwent 99mTc-Sestamibi tomography (to assess myocardial perfusion) at rest and during low dose (5 to 10 microg/kg/min) dobutamine echocardiography. Rest echocardiography and scintigraphy were repeated >1 month after revascularization. Nine patients had collaterals to the infarcted territory (group A), and 11 did not (group B). RESULTS: Baseline wall motion score was similar in both groups (score 15.9+/-1.3 vs. 17.4+/-2.0, p = NS), whereas significant changes at dobutamine and postrevascularization studies were detected (F[2,30] = 409.79, p < 0.0001). Wall motion score improved significantly (p < 0.001) in group A both at dobutamine (-5.3+/-2.2) and at postrevascularization study (-5.5+/-1.9), as well as in group B (-3.9+/-2.8 and -4.5+/-2.4, respectively). Baseline 99mTc-Sestamibi uptake was similar in both groups (62.9+/-9.7% vs. 60.3+/-10.4%, p = NS), whereas at dobutamine and postrevascularization studies a significant change (F[2,30] = 65.17, p < 0.0001) and interaction between the two groups (F[2,30] = 33.14, p < 0.0001) were present. Tracer uptake increased significantly in group A both at dobutamine (+ 10.9+/-7.9%, p < 0.001) and at postrevascularization study (12.1+/-8.7%, p < 0.001). Conversely, group B patients showed no change in tracer uptake after dobutamine test (-0.4+/-5.8, p = NS), but only after revascularization (+8.8+/-7.2%, p < 0.001). CONCLUSIONS: The increase in contractility induced by low dose dobutamine infusion in dysfunctional viable myocardium supplied by nearly occluded vessels occurs even in the absence of a significant increase in blood flow. (+info)
Prognostic value of dobutamine stress echocardiography in predicting cardiac events in patients with known or suspected coronary artery disease.
(18/9635)
OBJECTIVES: The study sought to determine the utility of dobutamine stress echocardiography (DSE) in predicting cardiac events in the year after testing. BACKGROUND: Increasingly, DSE has been applied to risk stratification of patients. METHODS: Medical records of 1,183 consecutive patients who underwent DSE were reviewed. The cardiac events that occurred during the 12 months after DSE were tabulated: myocardial infarction (MI), cardiac death, percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass surgery (CABG). Patient exclusions included organ transplant receipt or evaluation, recent PTCA, noncardiac death, and lack of follow-up. A positive stress echocardiogram (SE) was defined as new or worsened wall-motion abnormalities (WMAs) consistent with ischemia during DSE. Classification and regression tree (CART) analysis identified variables that best predicted future cardiac events. RESULTS: The average age was 68+/-12 years, with 338 women and 220 men. The overall cardiac event rate was 34% if SE was positive, and 10% if it was negative. The event rates for MI and death were 10% and 8%, respectively, if SE was positive, and 3% and 3%, respectively, if SE was negative. If an ischemic electrocardiogram (ECG) and a positive SE were present, the overall event rate was 42%, versus a 7% rate when ECG and SE were negative for ischemia. Rest WMA was the most useful variable in predicting future cardiac events using CART: 25% of patients with and 6% without a rest WMA had an event. Other important variables were a dobutamine EF <52.5%, a positive SE, an ischemic ECG response, history of hypertension and age. CONCLUSIONS: A positive SE provides useful prognostic information that is enhanced by also considering rest-wall motion, stress ECG response, and dobutamine EF. (+info)
Integrated evaluation of relation between coronary lesion features and stress echocardiography results: the importance of coronary lesion morphology.
(19/9635)
OBJECTIVES: The aim of this study was to analyze, in the same group of patients, the relationship between multiple variables of coronary lesion and results of exercise, dobutamine and dipyridamole stress echocardiography tests. BACKGROUND: Integrated evaluation of the relation between stress echocardiography results and angiographic variables should include not only the assessment of stenosis severity but also evaluation of other quantitative and qualitative features of coronary stenosis. METHODS: Study population consisted of 168 (138 male, 30 female, mean age 51+/-9 years) patients, on whom exercise (Bruce treadmill protocol), dobutamine (up to 40 mcg/kg/min) and dipyridamole (0.84 mg/kg over 10 min) stress echocardiography tests were performed. Stress echocardiography test was considered positive for myocardial ischemia when a new wall motion abnormality was observed. One-vessel coronary stenosis ranging from mild stenosis to complete obstruction of the vessel was present in 153 patients, and 15 patients had normal coronary arteries. The observed angiographic variables included particular coronary vessel, stenosis location, the presence of collaterals, plaque morphology according to Ambrose classification, percent diameter stenosis and obstruction diameter as assessed by quantitative coronary arteriography. RESULTS: Covariates significantly associated with the results of physical and pharmacological stress tests included for all three stress modalities presence of collateral circulation, percent diameter stenosis and obstruction diameter, as well as lesion morphology (p < 0.05 for all, except collaterals for dobutamine stress test, p = 0.06). By stepwise multiple logistic regression analysis, the strongest predictor of the outcome of exercise echocardiography test was only percent diameter stenosis (p = 0.0002). However, both dobutamine and particularly dipyridamole stress echocardiography results were associated not only with stenosis severity - percent diameter stenosis (dobutamine, p = 0.04; dipyridamole, p = 0.003) - but also, and even more strongly, with lesion morphology (dobutamine, p = 0.006; dipyridamole, p = 0.0009). As all of stress echocardiography results were significantly associated with percent diameter stenosis, the best angiographic cutoff in relation to the results of stress echocardiography test was: exercise, 54%; dobutamine, 58% and dipyridamole, 60% (p < 0.05 vs. exercise). CONCLUSIONS: Integrated evaluation of angiographic variables have shown that the results of dobutamine and dipyridamole stress echocardiography are not only influenced by stenosis severity but also, and even more importantly, by plaque morphology. The results of exercise stress echocardiography, although separately influenced by plaque morphology, are predominantly influenced by stenosis severity, due to a stronger exercise capacity in provoking myocardial ischemia in milder forms of coronary stenosis. (+info)
Functional status and quality of life in patients with heart failure undergoing coronary bypass surgery after assessment of myocardial viability.
(20/9635)
OBJECTIVES: The aim of this study was to evaluate whether preoperative clinical and test data could be used to predict the effects of myocardial revascularization on functional status and quality of life in patients with heart failure and ischemic LV dysfunction. BACKGROUND: Revascularization of viable myocardial segments has been shown to improve regional and global LV function. The effects of revascularization on exercise capacity and quality of life (QOL) are not well defined. METHODS: Sixty three patients (51 men, age 66+/-9 years) with moderate or worse LV dysfunction (LVEF 0.28+/-0.07) and symptomatic heart failure were studied before and after coronary artery bypass surgery. All patients underwent preoperative positron emission tomography (PET) using FDG and Rb-82 before and after dipyridamole stress; the extent of viable myocardium by PET was defined by the number of segments with metabolism-perfusion mismatch or ischemia. Dobutamine echocardiography (DbE) was performed in 47 patients; viability was defined by augmentation at low dose or the development of new or worsening wall motion abnormalities. Functional class, exercise testing and a QOL score (Nottingham Health Profile) were obtained at baseline and follow-up. RESULTS: Patients had wall motion abnormalities in 83+/-18% of LV segments. A mismatch pattern was identified in 12+/-15% of LV segments, and PET evidence of viability was detected in 30+/-21% of the LV. Viability was reported in 43+/-18% of the LV by DbE. The difference between pre- and postoperative exercise capacity ranged from a reduction of 2.8 to an augmentation of 5.2 METS. The degree of improvement of exercise capacity correlated with the extent of viability by PET (r = 0.54, p = 0.0001) but not the extent of viable myocardium by DbE (r = 0.02, p = 0.92). The area under the ROC curve for PET (0.76) exceeded that for DbE (0.66). In a multiple linear regression, the extent of viability by PET and nitrate use were the only independent predictors of improvement of exercise capacity (model r = 0.63, p = 0.0001). Change in Functional Class correlated weakly with the change in exercise capacity (r = 0.25), extent of viable myocardium by PET (r = 0.23) and extent of viability by DbE (r = 0.31). Four components of the quality of life score (energy, pain, emotion and mobility status) significantly improved over follow-up, but no correlations could be identified between quality of life scores and the results of preoperative testing or changes in exercise capacity. CONCLUSIONS: In patients with LV dysfunction, improvement of exercise capacity correlates with the extent of viable myocardium. Quality of life improves in most patients undergoing revascularization. However, its measurement by this index does not correlate with changes in other parameters nor is it readily predictable. (+info)
Biventricular repair approach in ducto-dependent neonates with hypoplastic but morphologically normal left ventricle.
(21/9635)
OBJECTIVES: Increased afterload and multilevel LV obstruction is constant. We assumed that restoration of normal loading conditions by relief of LV obstructions promotes its growth, provided that part of the cardiac output was preoperatively supported by the LV, whatever the echocardiographic indexes. BACKGROUND: Whether to perform uni- or biventricular repair in ducto dependent neonates with hypoplastic but morphologically normal LV (hypoplastic left heart syndrome classes II & III) remains unanswered. Echocardiographic criteria have been proposed for surgical decision. METHODS: Twenty ducto dependent neonates presented with this anomaly. All had aortic coarctation associated to multilevel LV obstruction. Preoperative echocardiographic assessment showed: mean EDLW of 12.4 +/- 3.03 ml/m2 and mean Rhodes score of -1.73 +/-0.8. Surgery consisted in relief of LV outflow tract obstruction by coarctation repair in all associated to aortic commissurotomy in one and ASD closure in 2. RESULTS: There were 3 early and 2 late deaths. Failure of biventricular repair and LV growth was obvious in patients with severe anatomic mitral stenosis. The other demonstrated growth of the left heart. At hospital discharge the EDLVV was 19.4+/-3.12 ml/m2 (p = 0.0001) and the Rhodes score was -0.38+/-1.01 (p = 0.0003). Actuarial survival and freedom from reoperation rates at 5 years were 72.5% and 46%, respectively. CONCLUSIONS: Biventricular repair can be proposed to ducto dependent neonates with hypoplastic but morphologically normal LV provided that all anatomical causes of LV obstruction can be relieved. Secondary growth of the left heart then occurs; however, the reoperation rate is high. (+info)
Chordal force distribution determines systolic mitral leaflet configuration and severity of functional mitral regurgitation.
(22/9635)
OBJECTIVES: The purpose of this study was to investigate the impact of the chordae tendineae force distribution on systolic mitral leaflet geometry and mitral valve competence in vitro. BACKGROUND: Functional mitral regurgitation is caused by changes in several elements of the valve apparatus. Interaction among these have to comply with the chordal force distribution defined by the chordal coapting forces (F(c)) created by the transmitral pressure difference, which close the leaflets and the chordal tethering forces (FT) pulling the leaflets apart. METHODS: Porcine mitral valves (n = 5) were mounted in a left ventricular model where leading edge chordal forces measured by dedicated miniature force transducers were controlled by changing left ventricular pressure and papillary muscle position. Chordae geometry and occlusional leaflet area (OLA) needed to cover the leaflet orifice for a given leaflet configuration were determined by two-dimensional echo and reconstructed three-dimensionally. Occlusional leaflet area was used as expression for incomplete leaflet coaptation. Regurgitant fraction (RF) was measured with an electromagnetic flowmeter. RESULTS: Mixed procedure statistics revealed a linear correlation between the sum of the chordal net forces, sigma[Fc - FT]S, and OLA with regression coefficient (minimum - maximum) beta = -115 to -65 [mm2/N]; p < 0.001 and RF (beta = -0.06 to -0.01 [%/N]; p < 0.001). Increasing FT by papillary muscle malalignment restricted leaflet mobility, resulting in a tented leaflet configuration due to an apical and posterior shift of the coaptation line. Anterior leaflet coapting forces increased due to mitral leaflet remodeling, which generated a nonuniform regurgitant orifice area. CONCLUSIONS: Altered chordal force distribution caused functional mitral regurgitation based on tented leaflet configuration as observed clinically. (+info)
Cardiac function and morphology studied by two-dimensional Doppler echocardiography in unsedated newborn pigs.
(23/9635)
The newborn pig is currently the most used species in animal neonatal research. Valid non-invasive monitoring is important in particular for long-term survival of unsedated animals. In the unsedated newborn pig (n = 35, median age 24 h, range 7-48 h) we standardized two-dimensional Doppler echocardiography and determined the normal ranges for cardiac function. Probe positioning had to be adjusted to the V-shaped thorax and the mid-line position of the heart. Six out of the sixteen animals < 20 h had a patent ductus arteriosus compared with one of the twenty animals > 20 h old. One atrial septal defect (5 mm) and one small ventricular septal defect were diagnosed. The average heart size was 0.7-0.9% of body weight which is similar to human infants of the same size. The mean aortic diameter was 6.0 +/- 0.5 mm (mean +/- S.D.) and cardiac output was 0.38 +/- 0.08 l min-1; both correlate with body weight (r = 0.80 and 0.73, respectively). Tricuspid regurgitation velocity was 3.0 +/- 0.4 m s-1 (mean +/- S.D.), giving an estimated pressure gradient across the tricuspid valve of 37 +/- 9.7 mmHg. The aortic diameter and the heart weight per kg body weight are comparable to those reported for preterm neonates. The cardiac output and velocities across the four valves are more comparable with term neonates. (+info)
Perivalvular abscesses associated with endocarditis; clinical features and prognostic factors of overall survival in a series of 233 cases. Perivalvular Abscesses French Multicentre Study.
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AIMS: The purposes of this study were to determine the clinical features and to identify prognostic factors of abscesses associated with infective endocarditis. METHODS AND RESULTS: During a 5-year period from January 1989, 233 patients with perivalvular abscesses associated with infective endocarditis were enrolled in a retrospective multicentre study. Of the patients, 213 received medical surgical therapy and 20 medical therapy alone. No causative microorganism could be identified in 31% of cases. Sensitivity for the detection of abscesses was 36 and 80%, respectively using transthoracic and transoesophageal echocardiography. Surgical treatment consisted of primary suture of the abscess (38%), insertion of a felt aortic or mitral ring using Teflon or pericardium (42%), or debridment of the abscess cavity (20%). The 1 month operative mortality was 16%. Actuarial rates for overall survival at 3 and 27 months in operated patients were 75 +/- 10% and 59 +/- 11%, respectively. Increasing patient age, staphylococcal infection, and fistulization of the abscess were found to be independent risk factors in both 1 month and overall operative mortality. Renal failure was a risk factor predictive of operative mortality at 1 month, whereas uncontrolled infection and circumferential abscess were regarded as risk factors predictive of overall operative mortality. CONCLUSION: The data determined prognostic factors of abscesses associated with infective endocarditis. (+info)