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Stress echocardiography has been validated for the evaluation of myocardial ischaemia and viability despite a semi-quantitative interpretation based on visual analysis of segmental myocardial thickening. The technique remains, therefore, partially subjective, which probably affects its diagnostic value and reproducibility, especially during the learning period of a non-expert operator. A first step towards better reproducibility was made possible by Second Harmonic imaging and standardised interpretation according to the recommendations of the American Society of Echocardiography. The quantification is based on the analysis of numerical data obtained by Doppler tissue imaging or color kinesis. Doppler Tissular Imaging in the pulsed mode with analysis of transparietal velocity gradients or regional deformation is currently under evaluation. However, the use of threshold values for myocardial velocities has been of little diagnostic value and the use of algorithms adjusted for age, heart rate and gender are necessary. Another approach is that of colour coding of endocardial displacement (Color Kinesis) with automatic contour detection. This relatively easy technique requires a shorter post-processing and the initial results are encouraging.

We studied the relation between the ischemic threshold at the onset of wall motion abnormality on exercise echocardiography (EE) and the severity of coronary stenosis in patients with 1-vessel coronary artery disease (CAD). We screened 216 consecutive patients who underwent coronary angiography and EE for suspected CAD. Ninety-five (74 men; age, 56 +/- 12 years) satisfied the study criteria, that is, the presence of 1-vessel disease or no evidence of CAD on angiography and a normal baseline echocardiogram. Eighty-seven patients had 1-vessel CAD on angiography, and exercise-induced wall motion abnormality occurred in 73 (77%). Optimal cutoff values of percent diameter stenosis and minimal lumen diameter for predicting a positive EE were 61% (sensitivity and specificity of 76%) and 1.12 mm (sensitivity and specificity of 74%). Among patients with positive EE, heart rate-blood pressure product at ischemic threshold was correlated with quantitative coronary stenosis (r = -0.72, P <.001). The ischemic threshold from continuous monitoring of left ventricular function during semisupine EE is correlated with the severity of coronary stenosis among patients with 1-vessel disease and a normal resting echocardiogram.

Hibernating myocardium is a term which covers chronic ischaemic left ventricular dysfunction which is potentially reversible after revascularisation. Hibernating myocardium is classically associated with chronic hypoperfusion responsible for hypocontraction and cellular degeneration. This "classical" conception has been questioned as some workers emphasise that the reduction in coronary reserve responsible for repeated episodes of ischaemia and stunning could be the main causes of myocardial dysfunction. Position emission tomography (PET), and, most of all, myocardial scintigraphy and dobutamine echocardiography are the most commonly used techniques for detecting hibernating myocardium. Their sensitivity is good but the specificity and positive predictive value of dobutamine echocardiography seems to be better than the isotopic techniques. Structural abnormalities of hibernating myocardium and the delay, which is often long, between revascularisation and improvement, may explain some of the discordances between these techniques. Irrespective of the term used, hibernation or chronic ischaemic left ventricular dysfunction with myocardial viability, the reported data is in favour of coronary revascularisation with improved long-term quality of life and reduced mortality in patients with positive viability tests.

As many techniques of medical investigation, echocardiography regularly benefits from technical innovations which, with application, prove to be extremely useful and, for some of them, even widen the field of investigation. The end of this decade has seen the introduction of major improvements. In daily practice, second harmonic imaging has been the most important technical advance with such improved quality of imaging that this mode has rapidly become the routine for transthoracic investigations in adults. All modern echocardiographs are, or can be, equipped at modest cost. Stress echocardiography, the diagnostic reliability of which is closely related to the quality of the imaging, has greatly benefited from this technique, to the point of obtaining equivalent results as nuclear medicine in the detection of myocardial ischaemia and cellular viability. The results are now sufficiently convincing for the technique to have a real prognostic value in myocardial ischaemia. Doppler tissue imaging is also a major advance but the clinical value is still under evaluation: the pulsed Doppler mode is quantifiable during the investigation, contrary to the calculation of transparietal velocity gradients which requires computerisation techniques not provided by all manufacturers. The regain in interest in contrast echocardiography is due to the development of agents which, injected intravenously, cross the pulmonary capillary barrier and opacify the left heart chambers. The reinforcement of the Doppler signal and improved detection of the endocardial echoes have justified the authorization of their commercialisation, but the essential point is their use in the investigation of myocardial perfusion which is under evaluation. Three-dimensional reconstruction has made great strides but its diffusion is still limited by the limited availability of the required powerful computers.

Arbutamine is a new catecholamine designed for use as a pharmacologic stress agent. This study compared the sensitivity of arbutamine with symptom-limited exercise to induce echocardiographic signs of ischemia. Arbutamine was administered by a computerized closed-loop delivery system that controls the infusion rate of arbutamine toward a predefined rate of heart rate increase and maximum heart rate limit. Beta blockers were stopped > or = 48 hours before both tests. Stress was stopped for intolerable symptoms, or clinical, electrocardiographic or echocardiographic signs of ischemia (new or worsening wall motion abnormality), target heart rate (> or = 85% age predicted maximum heart rate), or plateau of heart rate response. Thirty-seven patients were entered into the study (35 arbutamine and exercise, 1 arbutamine only, 1 exercise only), of which 30 had angiographic evidence of coronary artery disease (> or = 50% lumen diameter narrowing). Rate-pressure product increased significantly in response to both stress modalities (p < 0.001) and was significantly greater with exercise (11,308 +/- 2,443) than with arbutamine (9,486 +/- 2,479, p < 0.001). The time to maximum heart rate was longer during arbutamine stress echocardiography than during exercise testing (17.3 +/- 9.4 versus 9.3 +/- 4.2 minutes, respectively, p < 0.001). There were more patients with interpretable echo data for arbutamine (82%) than for exercise (67%). Sensitivity for recognition of myocardial ischemia was 94% (95% confidence interval 70% to 100%) and 88% (95% confidence interval 62% to 98%), respectively. The most frequent adverse events during arbutamine (n = 36) were dyspnea (5.6%) and tremor (5.6%). Two arbutamine stress tests were discontinued due to arrhythmias: 1 patient had premature atrial and ventricular beats, and the other had premature atrial contractions and atrial fibrillation. Arrhythmias were well tolerated and resolved without sequelae. In conclusion, the sensitivity of arbutamine to induce echocardiographic signs of ischemia was similar to that of exercise despite a lower rate-pressure product. Arbutamine was well tolerated and provides a reliable alternative to exercise echocardiography.

The prognosis of painless myocardial ischemia is similar to that of symptomatic ischemia. The Holter technique (and solid memory Holter in particular) is a simple method of detection which, taken together with exercise testing, enables the identification among coronary disease patients of a high risk group in whom effort ischemia is accompanied by episodes of ischemia under everyday conditions and in whom additional investigations (exercise thallium scan then coronary arteriography) and appropriate treatment, including transluminal angioplasty and aorto-coronary bypass if necessary, may be required. The role of drug treatment in silent ischemia has not yet been clearly defined. While electrical ischemia regresses significantly with the majority of standard drug regimens, and beta-blockers in particular, none has yet been confirmed as having a preventive effect against serious events following on from silent myocardial ischemia.