cardiovascular disorders
Complications of Acute Coronary Syndromes
Ventricular Arrhythmias
Ventricular arrhythmias are common and may result from hypoxia, electrolyte imbalance ( Hypokalemia , possibly Ventricular Premature Beats (VPB) , An IV beta-blocker early in myocardial infarction followed by continued oral beta-blockers reduces the incidence of ventricular arrhythmias (including Ventricular Fibrillation (VF) ) and mortality in patients who do not have heart failure or hypotension. Prophylaxis with other drugs (eg, After the acute phase, the presence of complex ventricular arrhythmias or nonsustained ventricular tachycardia, especially with significant left ventricular systolic dysfunction, increases mortality risk. An Implantable Cardioverter-Defibrillators (ICD) (ICD) should be considered and is indicated when the left ventricular ejection fraction is < 35%. Programmed endocardial stimulation can help select the most effective antiarrhythmics or determine the need for an ICD. Before treatment with an antiarrhythmic or ICD, coronary angiography and other tests are done to look for recurrent myocardial ischemia, which may require percutaneous coronary intervention or coronary artery bypass grafting. Nonsustained Ventricular Tachycardia (VT) (ie, Direct Current (DC) Cardioversion-Defibrillation is done for Polymorphic ventricular tachycardia Sustained (≥30 seconds) monomorphic ventricular tachycardia Any ventricular tachycardia with symptoms of instability (eg, heart failure, hypotension, chest pain) Ventricular tachycardia without hemodynamic instability may be treated with IVlidocaine,procainamide, oramiodarone. Some clinicians also treat complex ventricular arrhythmias with magnesium sulfate 2 g IV over 5 minutes whether or not serum magnesium level is low. Ventricular tachycardia may occur months after myocardial infarction. Late ventricular tachycardia is more likely to occur in patients with transmural infarction and to be sustained. The QRS duration is 160 millisecond. An independent P wave can be seen in II (arrows). There is a leftward mean frontal axis shift. Ventricular Fibrillation (VF) occurs in 5 to 12% of patients during the first 24 hours after myocardial infarction, usually within 6 hours. Late ventricular fibrillation usually indicates continued or recurrent myocardial ischemia and, when accompanied by hemodynamic deterioration, is a poor prognostic sign. Ventricular fibrillation is treated with immediate 