Management of perioperative dysrhythmias

This paper reviews cardiac dysrhythmias occurring in the perioperative period. Electrocardiography was the first application of electronic monitoring to anesthesia care. The detection of dysrhythmias remains the most important use of this technology today. While the description of dysrhythmias dates back to the early 1900's, the first large series was reported in 1936. Early descriptions of the kinds seen and the predisposing factors have changed little in the past 50 years. Several factors tend to emerge when one evaluates perioperative dysrhythmias. These are the anesthetic given, the site of surgery, abnormalities of blood gases or electrolytes, tracheal intubation, reflexes such as vagal slowing and the oculocardiac reflex, stimulation of the central nervous system the presence of pre-existing heart disease, and the use of intracardiac devices. In the evaluation of cardiac dysrhythmias several facts need to be determined. The most important is to determine if there is an underlying complication of anesthesia and surgery which may explain the dysrhythmia. In addition, one needs to evaluate the heart rate, the regularity, the number of P waves per QRS, and the configurations of the QRS. The anesthesiologist needs to determine whether the rhythm is dangerous to the patient and whether it requires treatment. The two major abnormalities of sinus rhythm are sinus bradycardia and the sinus tachycardia. Sinus bradycardia can be due to hypoxia, vagal stimulation, drug effects, a high sympathetic block or an acute myocardial infarction. Sinus tachycardia can be due pain, light anesthesia, hypovolemia, sepsis, hypoxia, hypercapnia and drug effects. The major atrial dysrhythmias are paroxysmal atrial tachycardia, atrial fibrillation and atrial flutter. Each require treatment if perfusion is impaired or if the heart rate is persistently elevated. The new agents esmolol and adenosine are particularly useful in managing atrial dysrhythmias. The major ventricular dysrhythmias are ventricular premature contractions, ventricular tachycardia and ventricular fibrillation. The later two demand emergency management with DC cardioversion when perfusion is impaired. The major abnormality of conduction is complete heart block which usually requires emergency treatment in the perioperative period. Prompt evaluation and management of perioperative dysrhythmias reduce anesthetic morbidity and mortality.