الفهرس 
Cardiac action potentialOnly 14 pages are availabe for public view
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Abstract
The cardiac assist devices are capable of supplementing and replacing cardiac pump function for variable length of time. It is assumed that if the devices used correctly in appropriate patients; mechanical circulatory assistance devices are successful in prolonging life expectancy and improving the quality of that life.
1) Artficial cardiac pacemaker:
Indications of permenant pacemakers include: sick sinus syndrome, Second and third degree AV block, LBBB, RBBB, congenital long Q-T syndrome, cardiomyopathy and decompensated heart failure.
2) Automatic implantable cardioverter-defibrillator (AICDs)
(AICDs) are devices resembling pacemakers and have the ability to treat dangerously fast rhythm disturbances of the heart, either via pacing or defibrillation. Many of these devices can also treat slow rhythms the same way as pacemaker.
A patient with an (AICD) coming for any surgery should have the device disabled before the start of the surgery. Electromagnetic interference (EMI) caused by diathermy and other equipment can have several undesirable effects. The current generated by the electrocautery may be misinterpreted as an arrhythmia by the (AICD). This can trigger a countershock, which has been reported to precipitate (VT).
The choice of anesthetic agents will depend on the level of myocardial dysfunction. Monitoring includes ECG and pulse oximetry. An external cardioverter /defibrillator should be ready in the OR in case it is needed. These patients often have a significant history of ventricular dysrhythmias and are at a significant risk of dysrhythmia recurrence. As such, continous ECG monitoring is required. Intraoperative dysrhythmias should be treated in the same manner as in patient without AICDs. Should it be necessary to cardiovert or defibrillate, paddles should not be placed directly over the AICD pulse generator, because this can damage the AICD circuitry.
3) The intraaortic balloon pump:
The (IABP) is a catheter mounted intravascular device designed to improve the balance between myocardial oxygen supply and demand by increasing diastolic blood pressure, thereby enhancing myocardial perfusion, and reduce the afterload and myocardial oxygen demand during the stress of anesthesia and surgery.
The primary indications for IABP in cardiac patient are inability to separate from CPB, poor haemodynamic function, and ongoing ischaemia following CPB despite increasing drug support.
Complications rates of the IABP range from 10 to 30 percent and include limb ischemia and vascular injury. Malposition, migration, and embolization of atherosclerotic material may lead to ischemia or infarction of brain, kidney, mesentry, and spinal cord tissue in addition to the limbs.
4) Ventriculr assist devices(VADs):
Ventricular assist devices are mechanical pumps that take over the function of the damaged ventricle and restore normal hemodynamics and end-organ blood flow. These devices are useful in two groups of patients. The first group consists of patients who require ventricular assistance to allow the heart to rest and recover its function. The second group consists of patients with myocardial infarction, acute myocarditis, or end-stage heart disease who are not expected to recover adequate cardiac function and who require mechanical support as a bridge to transplantation.
The anesthetic technique and drugs chosen should be appropriate for the planned operation. The anticoagulation required with most VADs contraindicates many forms of regional anesthesia, and a general an¬esthesia is usually the most appropriate choice.