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Pathophysiology Of Atrial Fibrillation

explanatory Essay
1507 words
1507 words
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Introduction 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 popul... ... middle of paper ... ...rombin time is necessary. This inconvenience and the significant drug-drug interactions implied with warfarin meant the development of new anticoagulant therapy such as dabigatran and rivaroxaban. Dabigatran is a direct thrombin inhibitor. In a random controlled trial conducted in 2009, Connolly et al (2009) reported similar rates of stroke and systemic embolism when comparing warfarin to dabigatran at a 110mg dose, but with lower rates of major haemorrhage. They also compared warfarin to dabigatran at a 150mg dose and reported significantly lower rates of stroke and systemic embolism in the dabigatran group but similar rates of haemorrhage14. Rivaroxaban is a factor Xa inhibitor. In a study carried out by Patel et al (2011), it was reported that in the treatment of AF, rivaroxaban was non-inferior to warfarin in the prevention of stroke or systemic embolism15.

In this essay, the author

  • Explains the electrophysiology of the heart, specifically the atria, in af. the ventricular rate depends on the rate and regularity of atrial activity and the balance between sympathetic and parasympathetic tone.
  • Explains that atrial fibrillation (af) is the most common arrhythmia and has implications for patients and anaesthetists alike.
  • Explains the mechanisms by which risk factors such as age, cardiac disease, and hypertension cause af.
  • Explains that pharmacological agents can be used in the treatment of peri-operative atrial fibrillation, including electrical cardioversion and antiarrythmic drugs.
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