الفهرس 
Acute Myocardial InfarctionOnly 14 pages are availabe for public view
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Abstract
In patients with acute myocardial infarction (MI), right ventricular (RV) involvement has clinical implications and is an independent predictor of the prognosis. Proximal occlusion of the right coronary artery (RCA), particularly that proximal to the RV branch, is accepted as the culprit commonly responsible for RVI (Dokainish et al., 2005).
The diagnosis of RV infarction is commonly based on the presence of ST-segment elevation in right precordial ECG leads such as V4R. However, these findings are transient and often disappear during the first hours after infarction. Also, these ECG changes may be subtle because of the relatively small muscle mass of the RV (Klein et al., 1983).
Echocardiography is the most commonly used imaging modality for routine clinical evaluation of the RV since it is widely available, extremely safe and relatively inexpensive (Gali et al., 2005). However, standard techniques are limited due to the complex RV geometry, retrosternal position, and the marked load dependence of RV function indices, so quantification is often only an estimation (Sanz et al., 2010).
Tissue Doppler imaging is a technique that offers information on myocardial velocities, allowing a quantitative assessment of myocardial function during the entire cardiac cycle (Jurcut et al., 2010).
This study aimed to investigate the peak myocardial systolic velocity (Sm) and myocardial performance index (MPI) of the right ventricle measured by pulsed wave tissue Doppler imaging (TDI) in correlation to the proximity of the culprit lesion along the course of RCA as a predictor of RV infarction in patients with first acute inferior myocardial infarction.
This study recruited 30 patient presented to the coronary care unit of Ain-Shams University Hospital and National Heart Institute with a first attack of Acute Inferior Myocardial Infarction in the period between 22nd of March 2010 till 21st of July 2010. All patients were subjected to detailed history taking, clinical examination, electrocardiogram, necessary laboratory tests, conventional M-mode, 2-D transthoracic echocardiographic examination, Doppler study, TDI and coronary angiography.
Based on coronary angiographic findings, patients were divided into 2 groups: Proximal RCA group B included 15 patients with the culprit lesion proximal to the RV branch and non-proximal RCA group A included 15 patients with the culprit lesion distal to the RV branch.
from the apical four-chamber view, at the level of the tricuspid annulus of the right ventricular free wall, a major positive Sm was recorded the systolic wave. The right ventricular MPI was calculated as (IVRT + IVCT)/ET, by using the values obtained from the right ventricular free wall.
Regarding the demographic data and the risk factors, they are of no statistically significance between the two groups.
Concerning the general examination in our study, only the raised JVP was of statistically significance between the two goups with P-value 0.001.
As for the ST-segment elevation of the ECG in the Rt precordial leads, it is of importance in group B with P-value < 0,001.
Only the RV wall motion abnormality regarding the conventional echocardiography is of statistical significance in group B compared to group A, with P-value 0.014.
Regarding the Tissue Doppler findings
It had been noticed that tricuspid annular systolic velocity decreases in group B patients (inferior MIs with suspected RVMIs and the culprit lesion is the proximal RCA) compared to group A patients with the culprit lesion is the distal RCA lesion.
A cutoff value 11.9 cm/s of tricuspid annular peak systolic velocity (ST) yielded an area under the curve of 95% (P<0.001) for differentiation between group B patients and group A with a sensitivity 80% and specificity 93.3%.
Regarding the calculated MPI in the study, a cutoff value of 0.5 was statistically significant in the differentiation between the two groups. Thus patients with calculated MPI ≥ 0.5 denoted proximal RCA as the culprit lesion with sensitivity of 80.0%, specificity 66.7%, PPV 70.6% and NPV 76.9%.
Therefore it was concluded that:
Patients who show an ST <11.9 cm/s and MPI ≥0.5 denoted proximal right coronary artery as the culprit lesion