[Evaluation of left ventricular function: echocardiography, MRI or CT?]. / Evaluation de la fonction ventriculaire gauche: échocardiographie, IRM ou scanner?

The objective of this article is to clarify the advantages and limits of echocardiography, MRI, and CT for the determination of left ventricular (LV) function, emphasising the importance of evaluating global ventricular function. MRI is the reference technique, owing to its precision, reproducibility, and innocuous nature. However, echography is performed much more frequently because it is more widely available and easier to carry out. It is our reference technique in everyday practice. More recently, synchronised multi-slice tomodensitometry has provided dynamic reconstructed images of the left ventricle throughout the cardiac cycle, offering a succession of short axis views covering the entire volume of the ventricle. These acquisitions, in addition to non-invasive coronary angiography, allow the LV ejection fraction to be determined. With MRI, study of the LV function does not require any contrast medium to be injected and makes use of effective semi-automatic segmentation programs.

[Echocardiography and mechanical complications of recent myocardial infarction]. / Echocardiographie et complications mécaniques de l'infarctus du myocarde récent.

The constantly advancing technology of echocardiography and its widespread usage in the intensive care unit has made it a routine examination in patients with acute myocardial infarction. It has become the reference method for diagnosis and monitoring of certain complications such as pericardial effusion, intra-ventricular thrombosis, ventricular aneurysm and mitral regurgitation. The echocardiographic description of these complications dates back to the 1980s during which prospective studies accurately described the principal abnormalities. These descriptions have not been much improved upon with the advent of new technology. On the other hand, the frequency of these complications assessed in an era when reperfusion by thrombolysis or primary angioplasty was much less common than today, has considerably decreased.

Stress haemodynamics for asymptomatic mitral regurgitation: how much does it help?

Stress haemodynamics for asymptomatic mitral valve regurgitation may prove helpful in determining the optimal timing for surgery.

[Stress echo and valvular heart disease]. / Echographie de stress et valvulopathies.

Stress echo has already been validated in some forms of valvular heart disease, especially in calcific aortic stenosis with low cardiac output and dynamic mitral regurgitation (MR) of valvular heart disease. Stress Doppler haemodynamics is a term used to differentiate these new indications from that of segmental wall analysis of the left atrium in ischaemic heart disease. In calcific aortic stenosis with low output, the haemodynamics with low dose dobutamine allows assessment of the real severity of the aortic stenosis and identification of the rare cases with mild stenosis: the principal indication remains the assessment of operative risk and long-term prognosis by the study of left ventricular contractile reserve. In cases of ischaemic left ventricular systolic dysfunction, the presence of mild mitral regurgitation (regurgitant surface area >20 mm2 at rest) is a poor prognostic factor. The dynamic character of mitral regurgitation is related to left ventricular remodelling which leads to deformation of the valvular apparatus (mitral tenting). Dynamic mitral regurgitation (regurgitant orifice area >13 mm2 on exercise) is a powerful prognostic factor, the role of which has recently been demonstrated in the genesis of acute pulmonary oedema. the other indications of stress haemodynamics are under validation, mainly the assessment of exercise capacity and valvular compliance in mitral stenosis or asymptomatic aortic stenosis.

[Dobutamine hemodynamics for aortic stenosis with left ventricular dysfunction]. / Rôle de l'hémodynamique Doppler de stress dans la prise en charge des rétrécissements aortiques avec dysfonction ventriculaire gauche.

Patients with aortic stenosis (AS) and left ventricular (LV) systolic dysfunction have a poor short-term prognosis. In this setting, the decrease in transaortic gradients has an independent prognostic value for operative risk and long-term outcome. The 2 main issues for these patients are: (1) The real severity of AS; (2) How to stratify operative risk and evaluate long-term prognosis. Dobutamine Hemodynamics has the potential to address these issues. In case of relative AS, valve area is increased by dobutamine (final valve area > 1.2 cm2 with a mean pressure gradient <30 mmHg); on the basis of published data, medical treatment is justified in this case. Left ventricular contractile reserve is defined an increase in stroke volume, by 20% or more, under dobutamine. Operative risk is between 5 and 11% in case of LV contractile reserve and long-term outcome is improved by surgery in this case. In contrast, operative risk varies from 30 to 60% in case of exhausted reserve; this risk is also determined by other factors such as the presence of coronary artery disease and associated comorbidities. All these parameters are factored into risk-benefit analysis in order to determine the best therapeutic approach for each patient.

[Echocardiography in elderly patients]. / Echocardiographie du sujet âgé

IN THE CONTEXT OF AGEING: The Doppler echocardiography is a non-invasive technique that permits assessment of the "physiological" ageing of the cardiac and vascular structures, notably including a concentric remodelling of the left ventricle associated with relaxation abnormalities, dilatation of the left atrium, valvular reorganisation and a modification in the large vessels. IN A PATHOLOGICAL CONTEXT: The Doppler echocardiography also detects the various cardiovascular affections related to ageing: valvulopathies, notably calcified aortic stenosis and mitral failure due to mitral anulus calcification or prolapsus of the valve; primary hypertrophic cardiomyopathy or secondary to arterial hypertension or an amyloidosis, and possibly leading to heart failure with spared systolic function, frequent in elderly patients; ischemic cardiopathies that have benefited, as in younger patient, from new echographical stress testing techniques, which safely study the variability in myocardial ischemia. Transoesophageal echography can also be performed in elderly patients, but the indications of this more invasive and less well-tolerated examination must be assessed case by case. It is very useful when an intra-parietal aortic hematoma is suspected or during aortic dissection or infectious endocarditis.

[Localization of mitral valve prolapse zones with multiplane transesophageal echocardiography]. / Localisation des zones de prolapsus valvulaire mitral en échographie transoesophagienne multiplan.

CONTEXT: There are few literature data on the localization and extent of mitral valve prolapse zones with transesophageal echocardiography (TEE). AIM OF THE STUDY: To assess a standardized imaging technique for the localization and extent determination of prolapse zones, based on 3 easily reproducible views with multiplane TEE. METHODS: Seventy patients with severe mitral regurgitation due to valve prolapse requiring a multiplane TEE prior to surgery (valve repair or replacement) have been retrospectively assessed. Data of TEE on the localization and extent of prolapse zones have been confronted to per-operative anatomical observations (gold standard). RESULTS: The sensitivity of TEE for the identification of isolated P2 prolapse, prolapse with commisural extension, isolated rupture of the posterior commisure and bi-valvular prolapses were respectively at 96%, 88%, 86% and 80%. The corresponding specificities were from 98% to 100%. CONCLUSIONS: The use of a standardized technique with the use of 3 easily reproducible incidences with multiplane TEE allows a precise definition of the localization and extent of mitral valve prolapse zones, in order to potentially indicate valve repair.

[Calcified aortic stenosis with left ventricular dysfunction and low transvalvular gradients. Must one reject surgery in certain cases?]. / Rétrécissement aortique calcifié avec dysfonction ventriculaire gauche et faibles gradients transvalvulaires. Doit-on récuser la chirurgie dans certains cas?

The natural history of severe aortic stenosis (aortic valve area < 1 cm2 or < 0.6 cm2/m2) with left ventricular systolic dysfunction and low transvalvular gradients (mean gradient < 40 mmHg) is mediocre in the short term and the operative risk is high. Dobutamine echocardiography provides a reliable evaluation of the aortic obstacle by diagnosing the rare cases of relative aortic stenosis in which the valve surface area has been underestimated because of a low cardiac output (aortic surface area > 1.2 cm2 with a mean gradient < 30 mmHg with dobutamine): in this case, the limited available data suggests that medical therapy with strict follow-up of its efficacy is the best management. The other use of dobutamine echocardiography is to assess left ventricular contractile reserve, defined as a increase > or = 20% in stroke volume under dobutamine. Cases with a contractile reserve have an operative risk of 5 to 10% and the medium-term benefits of valve replacement have been demonstrated. In the absence of contractile reserve, the operative risk is much grater, 30 to 60%, and also depends on other parameters such as the mean basal transaortic pressure gradient (risk five times greater in cases with a mean gradient < 20 mmHg), the need for coronary bypass surgery and associated co-morbid conditions. The surgical contraindications are in fact relatively few and concern patients with several risk factors: absence of contractile reserve itself is not a definitive surgical contraindication.

Impact of microvascular integrity and local viability on left ventricular remodelling after reperfused acute myocardial infarction.

OBJECTIVE: To assess left ventricular remodelling in patients with reperfused acute myocardial infarction and to study its relation to microvascular damage. PATIENTS: 25 patients successfully treated by primary percutaneous coronary angioplasty for acute myocardial infarction. SETTING: University hospital METHODS: Indexed end diastolic (EDVi) and end systolic (ESVi) volumes were assessed on admission and repeated at days 1 and 8. Coronary flow reserve (CFR) was assessed in the infarct related artery on day 1. Myocardial blood volume was assessed on admission and at day 8 by myocardial contrast echocardiography. In patients who manifested persistent myocardial dysfunction at hospital discharge (n = 21), local inotropic reserve was assessed by dobutamine echocardiography at day 7. RESULTS: On admission, patients with and without local viability had similar EDVi and ESVi (EDVi 67 (9) and 73 (14) ml/m(2), respectively; ESVi 34 (8) and 40 (11) ml/m(2), respectively; NS). EDVi increased to 97 (22) ml/m(2) in patients without local viability (p < 0.01 v admission) but remained unchanged at 70 (11) ml/m(2) in patients with viable myocardium (NS v admission). For pooled patient data, the percentage change in EDVi correlated with CFR (r = 0.76, p < 0.0001) and myocardial blood volume in the infarct territory (r = 0.80, p < 0.0001). CONCLUSION: Left ventricular dilatation may preferably occur in patients without local viability and is correlated with early CFR and extent of myocardial blood volume in the infarct territory.

[Can stress echocardiography by quantified?]. / Peut-on quantifier l'échocardiographie de stress?

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.

Stratification of single-vessel coronary stenosis by ischemic threshold at the onset of wall motion abnormality during continuous monitoring of left ventricular function by semisupine exercise echocardiography.

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.

Aortic stenosis with severe left ventricular dysfunction and low transvalvular pressure gradients: risk stratification by low-dose dobutamine echocardiography.

OBJECTIVES: We sought to assess risk stratification by using dobutamine stress echocardiography (DSE) in patients with aortic stenosis (AS) and severe left ventricular (LV) dysfunction. BACKGROUND: Few data are available on risk stratification for valve replacement in patients with AS, LV dysfunction and low transvalvular gradients. METHODS: Low-dose DSE was performed in 45 patients (16 women and 29 men; median [quartile range] age in years: 75 [69 to 79]; left ventricular ejection fraction: 0.29 [0.23 to 0.32]; aortic valve area [cm2]: 0.7 [0.5 to 0.8]; mean transaortic gradient [mm Hg]: 26 [21 to 33]). Patients were classified into two groups: group I (n = 32, LV contractile reserve on DSE) and group II (n = 13, no contractile reserve). Valve replacement was performed in 24 and 6 patients in groups I and II, respectively. RESULTS: Perioperative mortality was 8% in group I and 50% in group II (p = 0.014). Survival at five years after the operation was 88% in group I. Compared with medical therapy, valve surgery was associated with better long-term survival in group I (hazard ratio for death [HR-D] 0.13, 95% confidence interval [CI] 0.002 to 0.49) and reduced survival in group II (HR-D 19.6, 95% CI 2.7 to 142). The effect of valve surgery on survival remained significant in both groups after adjustment for age, diabetes, respiratory disease and hypertension. Medical therapy had the same effect in both groups. CONCLUSIONS: In patients with AS, LV dysfunction and low transvalvular gradients, contractile reserve on DSE is associated with a low operative risk and good long-term prognosis after valve surgery. In contrast, operative mortality remains high in the absence of contractile reserve.

[Chronic ischemic left ventricular dysfunction: myocardial hibernation?]. / Dysfonction ventriculaire gauche chronique d'origine ischémique: hibernation myocardique?

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.

[The best of echocardiography in 1999]. / L'essentiel de 1999 en échocardiographie.

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.

Prediction of functional recovery of viable myocardium after delayed revascularization in postinfarction patients: accuracy of dobutamine stress echocardiography and influence of long-term vessel patency.

OBJECTIVES: We sought to evaluate dobutamine stress echocardiography (DSE) for predicting recovery of viable myocardium after revascularization with cineangiography as a gold standard for left ventricular (LV) function. We studied the influence of late vessel reocclusion on regional LV function. BACKGROUND: Dobutamine stress echocardiography is a well established evaluation method for myocardial viability assessment. In previous studies the reference method for assessing LV recovery was echocardiography, long-term vessel patency has not been systematically addressed. METHODS: Sixty-eight patients with a first acute myocardial infarction (AMI) and residual stenosis of the infarct related artery (IRA) underwent DSE (mean +/- standard deviation) 21 +/- 12 days after AMI to evaluate myocardial viability. Revascularization of the IRA was performed in 54 patients by angioplasty (n = 43) or bypass grafting (n = 11). Coronary angiography and LV cineangiography were repeated at four months to assess LV function and IRA patency. RESULTS: Sensitivity and specificity of DSE for predicting myocardial recovery after revascularization were 83% and 82%. In the case of late IRA patency, specificity increased to 95%, whereas sensitivity remained unchanged. In the 16 patients with myocardial viability and late IRA patency, echocardiographic wall motion score index decreased after revascularization from 1.83 +/- 0.15 to 1.36 +/- 0.17 (p = 0.0001), and left ventricular ejection fraction (LVEF) increased from 0.52 +/- 0.06 to 0.57 +/- 0.06 (p = 0.0004), whereas in five patients, reocclusion of the IRA prevented improvement of segmental or global LV function despite initially viable myocardium. CONCLUSIONS: Dobutamine stress echocardiography is reliable to predict recovery of viable myocardium after revascularization in postinfarction patients. Late reocclusion of the IRA may prevent LV recovery and influence the accuracy of DSE.

Quantitative systolic and diastolic transmyocardial velocity gradients assessed by M-mode colour Doppler tissue imaging as reliable indicators of regional left ventricular function after acute myocardial infarction.

AIMS: The aim of this study was to determine whether myocardial velocity gradients assessed by M-mode colour Doppler tissue imaging could be of clinical relevance and represent reliable indicators of regional left ventricular function after acute myocardial infarction. METHODS AND RESULTS: Among 64 consecutive patients with a first acute myocardial infarction, in 50 who had a marked asynergy in the parasternal short-axis view at the mid-papillary muscle level, myocardial velocities and velocity gradients were assessed in the anteroseptum and posterior wall by M-mode Doppler tissue imaging. Similar measurements were obtained in 11 matched healthy volunteers who served as a control group. In patients with anterior myocardial infarction, the peak myocardial velocity gradient in the anteroseptum was significantly lower when compared with controls (mean +/- [SD] 0.0 +/- 0.5 vs 1.1 +/- 0.7 s-1 during systole, P < 0.01; and 0.3 +/- 0.6 vs 2.0 +/- 0.5 s-1 during diastole, P < 0.01). Conversely, the peak systolic myocardial velocity gradient in the posterior wall was significantly higher than in controls (2.6 +/- 1.2 vs 1.8 +/- 1.2 s-1, P < 0.05). In patients with inferior myocardial infarction, the peak velocity gradient in the posterior wall was significantly lower when compared with healthy subjects (0.9 +/- 0.6 vs 1.8 +/- 1.2 s-1 during systole and 1.4 +/- 1.4 vs 4.9 +/- 1.2 s-1 during diastole, both P < 0.01). The peak systolic tissue velocity gradient in the anteroseptum was significantly higher than in controls (2.1 +/- 1.0 vs 1.1 +/- 0.7 s-1, P < 0.01). CONCLUSION: The present study indicates that myocardial velocity gradients assessed by M-mode Doppler tissue imaging are of clinical relevance for the characterization of ischaemic myocardial dysfunction after infarction and may provide quantitative assessment of segmental left ventricular function in this clinical setting.

[Myocardial viability. Myocardial viability post-infarct: contribution of dobutamine-echography]. / La viabilité myocardique. Viabilité myocardique post-infarctus: place de l'échographie-dobutamine.

ROUTINE EXPLORATION: Echocardiography during dopamine perfusion has been widely proven as an effective tool for determining myocardial viability. Dobutamine has marketing authorization in France for stress-echocardiography and is widely used in clinical practice outside research protocols. The exploration must however be conducted within an appropriately equipped cardiac intensive care unit. Stress-echocardiography has certain advantages over isotropic techniques, in terms of equipment costs, examination time and exposure to isotopes. POST-INFARCTION: Dobutamine-echocardiography enables detection of viable myocardium within the infarct zone, evaluates the degree of residual ischemia in the infarct zone and provides information on prognosis. It would not however be reasonable to perform stress-echocardiography as a first line exploration after infarction. International guidelines recommend a sub-maximal ECG exercise test prior to coronarography. The contribution of stress-echocardiography after infarction is its ability to give precise information on myocardial viability and residual ischemia in one or more territories to compare with coronary lesions, thus allowing indication for revascularization. CHRONIC ISCHEMIC CARDIOPATHY: Dobutamine-echocardiography can be used to detect hibernating myocardium in patients with chronic ischemic cardiopathy. In this indication, the sensitivity of stress-echocardiography is slightly lower than thallium scintigraphy, but its specificity and positive predictive values are higher. The best predictive value is obtained with bimodal dobutamine-echocardiography: improve-med thickening at low doses and a degradation at high dose is predictive of functional improvement after revascularization in 72% of the cases. In more severe cases with ejection fraction < 35%, improvement in hibernating myocardium after revascularization leads to a significant improvement in left ventricular ejection fraction.