الفهرس 
PATHOPHYSIOLOGY AND CAUSES OF CARDIOGENIC SHOCKOnly 14 pages are availabe for public view
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Abstract
he heart is a muscular organ that is located in the thoracic cavity. It functions as a circulatory pump (longo et al., 2011).
Cardiogenic shock is a state of end–organ hypoperfusion due to cardiac dysfunction resulting in inability of the heart to maintain adequate cardiac output (Babaev et al., 2005).
Disorders that can result in the acute deterioration of cardiac function leading to CS include MI or ischemia, acute myocarditis, sustained arrhythmia, acute valvular catastrophe and decompensation of end-stage cardiomyopathy from multiple etiologies. CS is associated with the loss of more than 40% of the LV myocardial muscle (Dzavik et al., 2007).
Treatment focuses on improving the symptoms and preventing the progression of the disease. treatments include lifestyle modification and pharmacological agents(angiotensin-converting enzyme inhibitors, loop diuretics, beta-blockers, angiotensin receptor blockers, vasodilators, aldosterone receptor antagonists and positive inotropes). In severe cardiomyopathy, surgery should be considered as coronary angioplasty, heart valves surgery, MCS or cardiac transplantation (Naples et al., 2008).MCS can interrupt the inflammatory cascade initiated by the onset of shock and prevent progression to irreversible end-organ damage and subsequent death. An IABP is typically the first line of mechanical support used due to ease of insertion and minimal risk, but it is often insufficient in providing adequate support in patients with severe cardiogenic shock. Other options for temporary support include the Impella percutaneous ventricular assist device (PVAD), TandemHeart PVAD, venoarterial extracorporeal membrane oxygenation (ECMO) and the CentriMag device, which can be placed surgically or percutaneously (Esmore et al., 2007).
The continuous flow left ventricular assist device prolongs the lives of patients requiring long term MCS. Continuous-flow LVADs are new-generation devices with a number of major advantages over previous pulsatile technology. It is a surgically implanted, battery-powered pump that helps the left ventricle pump adequate amounts of blood to the body. The LVAD is implanted in the upper abdomen and connected to a power supply located outside the body. Blood is sent through a tube in the left ventricle into the LVAD, which pumps the blood through another tube into aorta. Continuous flow LVAD can be a destination therapy (Rogers et al., 2010)
Key selection criteria include assessment of the patient’s severity of illness and ability to successfully undergo the implant procedure. Pre-implant optimization of comorbid conditions is very important in minimizing the incidence and severity of post-operative adverse events and for enhancing survival. The most influential pre-implant measures are improving nutritional status, lowering pulmonary vascular resistance to optimize right-heart function and to reduce right atrial pressure and secondary hepatic congestion, aggressively managing volume to minimize right ventricular workload and hepatic congestion, optimizing coagulation, optimizing renal, hepatic, pulmonary, and neurologic function and treating any infection or providing prophylactic anti-biotic therapy (Lahpor, 2009).
The patient’s support system, psychosocial status, compliance with care, and ability to operate and care for external system components all warrant considerations in the patient-selection process.
In the immediate post-implant period, care must be taken to support the unassisted right ventricle. Invasive monitors for blood pressure, pulmonary artery catheterization, and echocardiography are essential to optimize left ventricular assist device settings and cardiac performance. Anticoagulation is necessary to prevent devastating thrombotic and embolic complications, but bleeding is a major source of morbidity due to inherent bleeding diatheses and prescribed anticoagulants. Infection of the device can be life threatening, and all infections must be aggressively treated to avoid seeding the device. Patients are at risk of ventricular arrhythmias because of their underlying disease, as well as the placement and position of the inflow cannula. Aortic valve stenosis and insufficiency develop over time and can lead to thrombosis or heart failure. Cardiopulmonary resuscitation with chest compressions must be performed with care (Bennett et al., 2010