**3. Contributing factors and causes of arrhythmias during anesthesia for surgery**

Although the incidence of intraoperative arrhythmias is extremely high, the majority of such arrhythmias are benign and self-limiting. They require no emergency treatment and respond well to pharmacologic interventions or both. However, in certain patients, some arrhythmias may pose an immediate threat to life by causing profound hemodynamic instability and require urgent clinical attention.

There are several factors likely to contribute to the generation of intraoperative arrhythmias, which can be classified according to patient, anesthesia, and procedures (**Table 2**) [5, 7]. Identifying the causes mainly responsible for intraoperative arrhythmias is prudent before instituting specific therapy or intervention.

Patients with pre-existing heart disease (e.g., myocardial ischemia) have a much higher incidence of arrhythmias intraoperatively. Intracranial pathology such as subarachnoid hemorrhage and raised intracranial pressure can result in ECG abnormalities because of stimulation of the autonomic nervous system.

Airway manipulation most often associated with hemodynamic disturbances is a well-described cause of intraoperative arrhythmias [4, 7, 8]. During anesthesia, arrhythmias can be produced in the presence of a variety of triggering agents and clinical situations such as light plane of anesthesia with hypertension and tachycardia, hypoxemia, and hypercarbia.

Vital organs, such as the brain, heart, and kidneys, must be perfused adequately during general anesthesia and surgery. Most of the anesthetic agents have direct myocardial depressant effects which result in reduced cardiac contractility and sympathetic stimulation of the peripheral vasculature. The net effect is a fall in cardiac output with a fall in perfusing pressure of vital organs secondary to vascular vasodilation. Conversely, tachycardia can have detrimental effects in patients susceptible to ischemia due to reduced myocardial filling time. Even relatively minor fluctuations in cardiovascular and hemodynamic parameters due to arrhythmias can have a significant incidence of various complications, including


#### **Table 2.**

*Contributing factors and causes of intraoperative arrhythmias.*

#### *Life-Threatening Cardiac Arrhythmias during Anesthesia and Surgery DOI: http://dx.doi.org/10.5772/intechopen.101371*

cardiovascular events, renal failure, infection, and cerebral infarction, particularly among the elderly co-morbid patients undergoing elective and emergency surgery. The use of halothane during induction in children as well as maintenance of anesthesia has been largely superseded by sevoflurane, which is safer. Electrolyte imbalances, abnormal blood gases, and direct cardiac stimulation via catheters influence the occurrence of arrhythmia and conduction abnormalities. The anesthesiologists should be aware of all the drugs used and able to manage the consequences accordingly [8, 9].

Surgical manipulation and cardiopulmonary bypass during cardiac surgery may precipitate arrhythmias. Vagal stimulation in surgical procedures such as during carotid surgery and peritoneal traction produces bradycardia, conduction block, or even asystole. Dental surgery causes profound stimulation of the autonomic nervous system. Thoracic surgery is associated with an incidence of atrial fibrillation.
