الفهرس 
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Abstract
Summary and conclusion
Duchenne muscular dystrophy, an inherited X-linked disease associated with absence of dystrophin, is characterized by progressive muscle weakness andinescapable cardiac involvement.
Children with DMD typically display skeletal muscle weakness by age 2–6 years.
Cardiomyopathy is nearly ubiquitous; although the age of onset varies considerably, this suggests that factors other than the absence of dystrophin contribute to cardiomyopathy.
Therapies addressing the skeletal muscle dysfunction and pulmonary manifestations of DMD improve survival, thus increasing the likelihood of eventually developing cardiac disease. Clinical guidelines recommend that evaluations for cardiomyopathy, arrhythmia, and heart failure be performed upon diagnosis, every 2 years thereafter until age 10 years; and then at least yearly thereafter.
The cardiomyopathy that develops in DMD is characterized by normal or thinned left ventricular (LV) wall thickness and progressive decline in ejection fraction or fractional shortening. Variable degrees of LV dilation occur. Abnormal LV relaxation has also been identified as an early manifestation in DMD.
Studies have shown that the timing and severity of cardiomyopathy is unrelated to the severity of skeletal muscle involvement in DMD. Howeverconducted a study to confirm the association of age with ventricular dysfunction and demonstrate that corticosteroid treatment, begun prior to echocardiographic evidence of ventricular dysfunction has a dramatic beneficial impact on the anticipated development of ventricular dysfunction .The incidence of cardiomyopathy in DMD increases with age, affecting 30 % of patients by14 years of age, 50 % of patients by 18 years of age, and up to 90 % of older patients.
Early detection of muscular dystrophy associated cardiomyopathy is important, because institution of cardioprotective medical therapies may slow adverse remodeling and attenuate heart failure symptoms in these patients.
However the timing of initiation of therapy remains in question, with no present evidence in the literature to suggest optimal ages or clinical stages at which cardiac medications should be initiated.
So we conducted our study to early detect subclinical cardiomyopathy as it became now a major cause of morbidity and mortality with increased life expectancy of DMD patients.
In this study, we conducted it to study cardiac functions as ejection fraction (%), left ventricular chamber dilatation in clinically suspected DMD patients by echocardiography and ECG. Furthermore, the role of myoglobin and other cardiac markers as Troponin I and Lactate Dehydrogenase LDH in early detection of myocardial damage in children with DMD were studied.
Our study involved 28 clinically suspected Duchenne muscular dystrophy children and 47 age matched healthy male children as control .The Mean ± SD of age of study group was 7.29±3.24 years range from 3-14 years and the Mean ± SD of age of the control group was 8.06±2. 86 years with age range from 3 to 14 years (p value 0.28).
About 25% of studied cases had relatives with DMD; (p value: 0.001).consanguinity was present in (35.7%) of patients.Positive
The studied populations were subjected to cardiac assessment;all patients showed to have normal blood pressure, pulse and palpation of the precordium. No change in heart auscultation and rhythm was clinically observed, in any of the cases.
We found that:
There was astatistically significant difference in ECG changes between -DMD patients and control children;ECG of DMD patients showed thateight cases (28.57%) had sinus tachycardia, (P value: 0.0001).
- In our study we also found prolonged QTc interval in 11(39.29%) cases of 28 cases.p value : <0.0001).
-Other parameters of ECG were normal for age. No type of arrhythmia apart from sinus tachycardia could be detected.
-Echocardiography of our patients revealed signs of decreased systolic function in 7 (25%) patients. Ejection fraction (EF) below 56% with means ± SD 59.86 ± 10.20 and range from 45 to 80 ;( P value :< 0.0001).
FS (fraction shortening) was reduced <28%; in 7(25%)of patients.-
-One patient (3.57%) had mild dilation of the left ventricular cavity which was statistically not significant, (P value: 0.37).
-In our study we found that all the cases have high CPK level (creatine phosphokinase) ;While CPK level remained unchanged in controls.
-Nineteen cases (67.86%) have high LDH level; P value : <0.0001.
- The mean ± SD of serum myoglobin (ng/ml) of (DMD) patients was higher relative to that of healthy controls (but still normal) with statistically significant difference (P value: 0.01).
-Concerning presence of difference between the mean ± SD of serum of troponin I (U/L) of (DMD) patients and that of controls; there was no statistically significant difference between (DMD) patients and control children (p value: 0.37).
Based on this study, we recommend:
-Informing pediatricians toroutinely doelectrocardiography for (DMD) patients on diagnosis and yearly thereafter as ECG manifestations e.g sinus tachycardia is an early alarm of developing cardiomyopathy.-Echocardiography should be done as part of diagnosis even without symptoms and yearly thereafter.
-Cardiac markerse.gLDH,myoglobin also are good detectors of cardiomyopathy.early
-Asymptomatic cardiomyopathy is nearly aconstant feature of DMD so we should search for it before overt symptoms develop as symptomatic cardiomyopathy in (DMD) patients is an ominous sign.