الفهرس 
Myocardial infarctionOnly 14 pages are availabe for public view
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Abstract
Myocardial infarction (MI) is the irreversible necrosis of heart
muscle secondary to prolonged severe ischemia. Approximately 1.5
million cases of myocardial infarction occur annually in the United
States. Infarctions can be classified into ST elevation (STEMI) and non-
ST elevation (NSTEMI) myocardial infarctions. STEMI can be
subdivided into anterior, lateral, inferior, posterior and right infarctions
based on ECG pattern of ST elevation.
Assessment of Left ventricular (LV) function has become standard
practice after MI while assessment of the right ventricular (RV) function
remains uncommon. Recent studies suggest that RV function is an
independent predictor of mortality and development of heart failure (HF)
in patients with known LV dysfunction due to MI.
In common practice, clinicians largely rely on non‐invasive
imaging methods for assessment of RV function, thus two dimensional
(2-D) echocardiography is the mainstay for analysis of RV function.
Recently alternative techniques have been proposed, including tissue
Doppler imaging (TDI) techniques, three dimensional (3D)
echocardiography, magnetic resonance imaging (MRI) and speckle
tracking echocardiography (STE). However, two-dimensional (2D)
speckle tracking echocardiography (STE) provides more accurate
estimates of RV function when compared to cardiac MRI reference, a
finding that encouraged us to use this technique in our study.
Speckle tracking allows the assessment of myocardial strain and
strain rate. Myocardial strain is a dimensionless index of tissue
deformation expressed as a fraction or percent change. Myocardial
lengthening gives a positive and shortening gives a negative strain value.
Strain rate (SR) measures the local rate of deformation per unit time.
Strain can be further subdivided into longitudinal, radial and
circumferential strain. Longitudinal strain represents myocardial
deformation directed from the base to the apex. Radial strain represents
radially directed myocardial deformation, i.e. toward the center of the LV
cavity, and thus indicates the LV thickening and thinning motion during
the cardiac cycle. Circumferential strain represents LV myocardial fiber
shortening along the circular perimeter observed on a short-axis view.
Two-dimensional (2D) strain and strain rate (SR) analyses are novel
Doppler-independent techniques to obtain measurements of myocardial
movement and deformation.
Aim of the work:
According to the previous data, we designed this work to study the
right ventricular function using 2-D echocardiographic speckle tracking
to measure longitudinal strain and strain rate in patients experiencing
anterior myocardial infarction. Furthermore, the right ventricle was also
assessed by measuring its 2-D internal dimensions, calculating fractional
area change (FAC), measuring tricuspid annular plane systolic excursion
(TAPSE), estimating myocardial performance index (MPI) and
identifying the tissue doppler peak S wave on RV free wall at the level of
tricuspid valve annulus. It was important to assess the left ventricle by conventional and 2-D speckle tracking echocardiographic techniques also
in order to study the RV function in view of LV dysfunction.
Subjects and methods:
This study was carried out on 45 subjects in the Cardiology
Department, Faculty of Medicine, Menoufia University in the period
between the 1/1/ 2014 and 31/8/2014. Subjects were divided into group I
(25 patients) and group II (20 controls). Patients were diagnosed as
having anterior STEMI for the first time within 1 week of presentation
treated with thrombolytic therapy in the first 24 hours.
All subjects were subjected to full history taking, thorough clinical
examination and echocardiographic assessment using GE Healthcare
Vingmed Horten Norway vivid S5 echo-machine and its 3S transducer.
Images were analyzed offline using EchoPac version 110.1.2 software.
Conventional echocardiographic measurements of the left ventricle
included (LVEDD, LVESD, LVIVSd, LVPWd, EF M-Mode and EF
Simpson’s technique). Right side measurements included right atrial and
right ventricular internal dimensions, TAPSE, FAC and tissue doppler
peak S wave for RV free wall at tricuspid valve annular level. Twodimensional
speckle tracking was done to evaluate peak longitudinal
systolic strain (PLSS) and strain rate at peak systole (SRs s-1), early
diastole (SRe s-1) and late diastole (SRa s-1) for all myocardial segments
(basal, mid and apical) of the left and right ventricles. Average RV free
wall PLSS was calculated as the average of PLSS of its 3 segments.
Global RV PLSS was calculated as the average of PLSS of the 3
segments of RV free wall and septum. Global LV PLSS was calculated
as the average of PLSS of its six walls (septum, lateral, anterior, inferior,
posterior and anteroseptal walls).
Coronary angiography was essential to evaluate the coronary
arteries and exclude patients having a significant lesion in the right
coronary system causing › 50% luminal diameter stenosis. This was done
to exclude RV dysfunction secondary to impaired coronary blood supply.
All the obtained data were tabulated and then statistically analyzed.
Results:
The demographic data of the patients in this study revealed that
patient’s age ranged between 33-74 years with a mean ± SD of 56.160 ±
10.688. There were 5 patients (20 %) between 30-50 years, 17 (68%)
patients between 50-70 years and 3 (12%) patients more than 70 years.
Patient’s height ranged between 162-184 cm with a mean ± SD of
176.640 ± 6.550. The weight of patients ranged between 70-95 kg (mean
± SD of 84.320 ± 6.945) and their body mass index ranged between 22-
29.3 (mean ± SD of 27.004 ± 1.757). The majority of patients (76%)
with myocardial infarction in our study were males and only 24% were
females. In our study, the incidence of myocardial infarction is
significantly higher in patients with DM, Htn, dyslipidemia, and smoking
(p‹0.05), whereas positive family history of IHD does not show a
statistically significant impact on occurrence of MI (p›0.05).
The heart rate of patients (range between 65-110 beats/minute with
a mean ± SD of 84.56 ± 11.889) was higher than that of the control group
(range between 61-92 beats/minute with a mean ± SD of 75.35 ± 8.431).
This difference reaches a statistically significant level (p‹0.05).
Ejection fraction by M mode, ejection fraction by Simpsons
techniques and fractional shortening, revealed a high statistically
significant difference between the two groups with group I (patients)
showing a significant reduction in values (p‹0.005). Similarly, there was
a significant reduction in interventricular septum diastolic dimension in
group I (p‹ 0.05). No statistical difference between the two groups was
found regarding left ventricular end diastolic internal dimension, left
ventricular basal posterior wall diastolic thickness or left atrial and aortic
root dimensions (p›0.05)
On evaluation of the right side of the heart, no significant
difference was detected in right atrial and the right ventricular basal and
mid cavity internal dimensions. Regarding tricuspid annular plane
systolic excurtion (TAPSE), there was a significant statistical significance
between the two groups (p<0.001) with group I showing marked
reduction of values (Mean ± SD 1.940 ± 0.269 in group I vs 2.355 ±
0.343 in group II) (Table 2). There was also a significant reduction in
fractional area change (FAC) in the apical 4 chamber view, our results
showed that the patient group was more affected and FAC values were
reduced in comparison to the control group (Mean ± SD 49.600 ± 9.363
for group I vs Mean ± SD 55.650 ± 8.177 for group II) (p<0.05).
Furthermore a highly significant reduction in lateral tricuspid annulus
DTI peak S wave (p‹0.005) was discovered in group I (Mean ± SD
12.560 ± 1.685 in group I vs 15.500 ± 2.373 in group II) (p<0.001). On
calculating the RV MPI there was a significant difference between the
two groups being markedly elevated in the patient group with (Mean ±
SD 0.5637 ± 0.089) in comparison to control group with (Mean ± SD
0.3613 ± 0.067) (p<0.05).
Regarding peak longitudinal systolic strain (PLSS or Esys %), the
right ventricular free wall segments (basal, mid and apical) showed no
significant difference between the two groups (p›0.05). Basal septal,
basal posterior and basal inferior wall segments also showed no
significant difference between the two groups (p›0.05). The remaining
segments of the left ventricle showed a highly significant statistical
reduction in group I when compared to group II (p‹0.005).
As far as the strain rate at peak systole (SRs s-1) is concerned; the
right ventricular free wall segments (basal, mid and apical) showed no
significant difference between the two groups (p›0.05). The basal lateral,
basal anterior, basal posterior and basal inferior segments also showed no
significant difference between the two groups (p›0.05). The mid
posterior, mid inferior and basal septal segments show a significant
difference between the two groups being reduced in group I (p‹0.05).
The remaining myocardial segments showed a highly significant
statistical reduction in group I when compared to group II (p‹0.005).
Regarding early diastolic strain rate (SRe s-1); the right ventricular
free wall segments (basal, mid and apical) showed no significant
difference between the two groups (p›0.05). Whereas, a significant
difference was detected in the mid and basal septal and basal posterior
segments between the two groups being lower in group I (p‹0.05). The
remaining myocardial segments showed a highly significant difference
between the two groups being significantly reduced in group I (p‹0.005).
Regarding late diastolic strain rate (SRa s-1), the right ventricular
free wall segments (basal, mid and apical) showed no significant
difference between the two groups (p›0.05). The apical septal, apical
lateral and apical anteroseptal segements showed a highly significant
difference between the two groups being lower in group I (p‹0.005). The
mid lateral, apical posterior, mid and basal anteroseptal segments showed
a highly significant statistical difference between the two groups being
significantly reduced in group I (p‹0.005).
Global LV PLSS was significantly reduced in group I with a mean
± SD -9.584 ± 6.575 when compared to group II with a mean ± SD -
19.915 ± -2.073 (p‹0.005). The average RV free wall PLSS showed a
slight reduction in values but not reaching a statistically significant value
with a mean ± SD -25.027 ± 5.583 for group I and -26.550 ± 2.625 for
group II respectively (p›0.05). SRs s-1 with a mean ± SD -2.076 ± 0.603
for group I vs -1.856 ± 0.273 for group II indicates no statistically
significant difference. Septal wall average PLSS and SRs s-1 were
significantly reduced in group I (mean ± SD -10.627 ± 6.106 and -0.766 ±
0.268 respectively) when compared to group II (mean ± SD -19.683 ±
2.569 and -1.228 ± 0.317 respectively) (p‹0.005). Global RV PLSS was
significantly reduced in group I (mean ± SD -18.276 ± 3.956) vs group II
(mean ± SD -23.120 ± 1.959) (p‹0.005). There was a significant positive
correlation (r = 0.578) between Global RV PLSS and Global LV PLSS
(p‹0.005).
Conclusions:
The Global RV PLSS is significantly reduced in patient with
anterior STEMI mainly due to reduction of average septal PLSS caused
by the infarction. Other parameters of the RV as TAPSE, FAC, MPI and
DTI peak S wave are also affected. Furthermore, LAD territory infarction
affects the PLSS, SRs s-1 and SRe s-1 of a wide area of the LV. The
global LV PLSS along with EF (by M-mode and Simpsons biplane
technique) appear to be significantly affected in these patients.