الفهرس 
Chapter I Heart failureOnly 14 pages are availabe for public view
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Abstract
Cardiac resynchronization therapy (CRT) is proved as an effective treatment for moderate to severe heart failure. It reduces all-cause mortality in patients with advanced heart failure . There is strong evidence that CRT reduces mortality and hospitalization, improves cardiac function and structure in symptomatic chronic heart failure patients with optimal medical treatment, severely depressed LVEF (i.e. ≤35%) and complete LBBB. However 30% of patients may show negative response to CRT therapy. Therefore, optimization of CRT therapy in patients with heart failure seems to be a main subject for study in our researches. Methods of optimization includes optimization of medical therapy, control of risk factors and comorbidities, and optimization of device implantation and programming. Overall, studying the correlation between QRS duration and cardiac output will improve CRT programming optimization techniques . Therefore, we studied this relation through 100 CRT already implanted patients, 60 males and 40 females. They were requested to do a simple electrocardiographic and echocardiographic study . We focused on QRS duration, LVOT VTI and LVOT diameter. We found a significant negative correlation between QRS duration and LVOT VTI and SVi. Patients were divided into responders and non responders according to their clinical response. CRT response is better in female patients than in males, It is also found that those with lower BSA and thin patients had a better response than obese patients. We also found that younger patients had a better response than older ones. Smokers had less response to CRT than non smoker patients, also patients with ischemic heart disease had a worse response than non ischemic patients. Patients with longer period since CRT implantation had a better response than those with recently implanted CRT device. QRS duration was shorter in the responder group than non responder ones, and inversely the LVOT VTI was higher in the responders than non responders, and so, we also found that the responders had a higher CO than non responders. i.e. The responder group had a significantly shorter QRS duration and higher LVOT VTI and CO post implantation. There was a significant negative correlation between QRS duration and LVOT VTI, the higher the LVOT VTI post implantation the shorter the QRS complex and the better the response. This raises the importance of quadripolar lead or His bundle pacing in improving the response, as both will lead to a shorter QRS complex. Finally, post implantation cut off value of QRS duration (<130) predict higher LVOT VTI and also the post implantation benefit for the patient with CRT implanted.