Atrial fibrillation (AF) is a cardiac arrhythmia. It is the most common arrhythmia and it has implications for patients and anaesthetists alike. The anaesthetist must take into consideration the physiological and pharmacological implications of this common arrhythmia.
In a healthy individual receiving a general anaesthetic, the anaesthetist must be aware of the causes and treatment of acute onset AF, both intra-operatively and peri-operatively. Patients with AF often develop a decline in left ventricular performance and other hemodynamic instabilities including reduced diastolic filling and tachycardia mediated cardiomyopathy1, all of which can reduce cardiac output and pose difficulties for the anaesthetist.
One of the characteristics of the common disorder, and perhaps the most worrisome for the patients affected, is decreased blood flow in the atria, which is associated with and allows thrombi to form. Embolism from the atria can cause cerebrovascular accidents, which can be devastating to the affected individuals and their families.
Even over the short course of my clinical experience thus far, various consultants have asked my colleagues and I about the pathophysiology of AF, the causes of AF and most have been asked to describe the rhythm of the pulse of AF. Hospital doctors do not have to look far to find a patient with the often symptom less disorder, and quiz medical students on it. A study conducted in Trinity College, Dublin by Finucane et al (2011) reported that 10.8% of Irish men over the age of 80 are living with AF2. They also reported prevalence across all age groups of 3.2%. AF is highly prevalent in Ireland today, and is set to become more prevalent in the country, in keeping with our ageing population. In this essay I will be discussing the causes, pathophysiology and treatment of this disorder.
AF can be paroxysmal, persistent or permanent. Paroxysmal AF ends without intervention, within 7 days. Persistent AF continues after 7 days and requires pharmacological or electrical intervention in order to terminate it. If the arrhythmia is not cardioverted by pharmacological or electrical means, usually after 1 year, it is termed permanent5.
It is clear that there are independent risk factors for AF including age, diabetes, hypertension, congestive heart failure and mitral valve disease6. AF is associated with cardiovascular causes and non-cardiac causes. Cardiovascular causes include hypertension, coronary heart disease, cardiomyopathy, mitral valve disease, cardiac surgery, myocarditis, pericarditis and Wolff Parkinson-White syndrome.
Non-cardiac causes include alcohol, hyperthyroidism, pulmonary disorders, pulmonary embolism, obstructive sleep apnea, thoracic surgery, obesity and sepsis.
The mechanisms by which risk factors such as age, cardiac disease and hypertension cause AF are poorly understood. It has been suggested that certain ‘triggers’ cause AF7. It has been suggested that...