J.L. Rodrigo

Isovolumic Contraction Time by Pulsed-Wave Doppler Tissue Imaging in Aortic Stenosis

BACKGROUND Doppler Tissue Imaging (DTI) has been evaluated in ischaemic heart disease and some cardiomyopathies. In patients with aortic stenosis (AS), left ventricular contraction is slowered. This study aimed to evaluate the possible role of the measurement of isovolumic contraction time (ICT) by DTI in the evaluation of AS severity. METHODS The study population constitutes 30 patients: 15 with AS (nine severe and six non-severe) and 15 control subjects. All of them had normal systolic function, sinus rhythm, and absence of ischaemic heart disease of conduction abnormalities. ICT was defined as the time from the onset of the QRS complex to the beginning of the DTI systolic wave. The correlation between ICT and aortic area obtained by continuity equation, as well as the diagnostic value of ICT in the identification of severe AS were studied. RESULTS ICT was significantly increased in patients with severe AS (98+/-27 versus 65+/-21 ms, p=0.024). There was a significant correlation between ICT and aortic area (r=-0.56; p=0.035). The receiver operator characteristic curve of ICT in the identification of severe AS yielded an area under the curve of 0.852 (95% confidence interval: 0.665-1.0). The two best cut-points were >73 ms (88% sensitivity, 77% specificity) and >85 ms (78% sensitivity, 83% specificity). A value of >41 ms had a 100% sensitivity, but only a 17% specificity, and >91 ms showed a 100% specificity, but only a 44% sensitivity. CONCLUSIONS ICT measured by pulsed-wave DTI is increased in patients with aortic stenosis.

Myocardial contrast echocardiography in coronary artery disease

Myocardial contrast echocardiography (MCE) allows the assessment of myocardial perfusion by imaging the coronary microcirculation. The development of new contrast agents and new diagnostic tools far assessing myocardial perfusion by means of MCE has led to a new field of applications far patients suffering from ischemic heart disease. Several studies have shown that MCE is a feasible and accurate method to evaluate patients with: a) acute coronary syndromes: MCE is useful before the epicardial reperfusion to delineate the area at risk and to assess the collateral-derived myocardial blood flow, and after the epicardial reperfusion to detect the non-reflow phenomenon; b) chronic coronary syndromes: MCE allows the detection of significant coronary stenosis by means of stress methods and methods without any stress; c) myocardial viability and hibernating myocardium: MCE helps to predict functional recovery of akinetic segments. In these settings, MCE is not only useful as a diagnostic tool but also provides prognostic information. MCE is a technique in constant development. Among the latest advances we note the development of transesophageal probes with second-harmonic image that allows assessment of myocardial perfusion in a more accurate way. This technique should introduce MCE into new clinical fields, especially the evaluation of myocardial perfusion during cardiac operations. Another recent development is in parametric imaging techniques. These consist in obtaining time curves for all the pixels in the image instead of working only with a few separate regions of interest. A parameter scan is computed far any pixel showing their value as a color overlay in the parametric image. Summarizing, we can say that MCE is crossing from the experimental laboratory to the daily clinical practice far the evaluation of ischemic heart disease. MCE provides an interesting tool that offers the potential of a complete evaluation of patients with chronic coronary artery disease. This includes both diagnostic and prognostic evaluation.

Myocardial perfusion in real-time using power modulation: In vivo evidence for microcirculatory damage after acute myocardial infarction

BACKGROUND AND OBJECTIVES In addition to the myocardium, the microvasculature may be also damaged in acute myocardial infarction. The aim was to evaluate the capability of myocardial contrast echocardiography in the detection of microvasculature damage after myocardial infarction. PATIENTS AND METHODS Twelve patients with recent acute myocardial infarction and five control subjects with normal coronary arteries and without history of myocardial infarction were studied. Myocardial contrast echocardiography with power modulation was performed, and quantitative data were measured off-line. Power modulation uses a combination of low (0.1) and high (1.7) mechanical indexes, allowing a real-time evaluation of myocardial perfusion. Contrast agent was administered as a 3-min bolus. The quantitative analysis was performed off-line by a different blinded investigator. The refilling velocity was calculated as the difference between the peak myocardial refilling value and the value at 1 s after the impulse divided by the time from the first second after the impulse to the peak refilling value. RESULTS Eighty-one myocardial segments (75%) were analysed qualitatively and quantitatively in AMI patients, and 18 (60%) in control subjects (P=NS). The peak refilling intensity was not significantly different in patients and control subjects (6.62+/-5.85 vs. 7.53+/-4.06 dB, respectively). However, time to peak refilling intensity was significantly longer (5.25+/-1.57 vs. 4.00+/-0.53, P=0.004) and the velocity of refilling was significantly lower (2.74+/-5.34 vs. 6.58+/-8.02, P=0.028) in patients with myocardial infarction. CONCLUSION There is microvasculature damage after myocardial infarction that is reflected as a delayed velocity of refilling in myocardial contrast echocardiography.