Role Of Transthoracic Echocardiography

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Transthoracic echocardiography (TTE) can be helpful in the management of AF by (1) identifying pathological conditions that may predispose to AF, and (2) identifying conditions that may increase the risk of thromboembolism (Table 1). For patients who present with their initial episode of AF, a search is usually made to determine the most likely "associated" systemic condition. The most common associated conditions include a history of systemic hypertension or coronary artery disease. Also to be considered are mitral valve disease (especially rheumatic mitral stenosis), pneumonia/ sepsis, clinical or subclinical thyrotoxicosis (especially in the elderly), pericarditis, pulmonary embolism, pharmaceuticals (e.g., aminophylline), and excess caffeine or alchohol ingestion (Table 2). Patients are often referred for a TTE to investigate for occult mitral stenosis, to assess the severity of mitral regurgitation (with consideration of mitral valve surgery if it is severe), for assessment of left atrial size (but TTE is not sufficient for assessment/exclusion of atrial thrombi), for the presence of a pericardial effusion (although the absence of

Table 2

Atrial Fibrillation: Associated Conditions

Conditions associated with atrial fibrillation

• Hypertension

• Coronary artery disease

• Valvular heart disease (especially mitral stenosis)

• Pulmonary disease, including pulmonary embolism

• Hyperthyroidism (clinical and subclinical)

• Sepsis including pericarditis

• Postcardiac surgery (especially valvular surgery)

• Drugs, including ethanol an effusion does not exclude the clinical diagnosis of pericarditis), and for assessment of left ventricular systolic function. Information regarding left ventricular systolic function is frequently helpful for guiding the choice of ventricular rate controlling agent with P-blockers used for patients with preserved systolic function and digoxin/diltiazem or a combination for patients with depressed left ventricular systolic function. Very rarely, AF may present as a manifestation of pulmonary embolism (severe right ventricular enlargement with free wall hypokinesis) or aortic stenosis. For patients who present with recurrent AF, repeated TTE studies are generally not fruitful (unless there has been a change in presentation).

CARDIOVERSION FOR AF: THE ROLE OF ECHOCARDIOGRAPHY

Among patients with persistent AF, cardioversion to sinus rhythm is often performed to relieve symptoms and improve cardiac output, but should not be performed to specifically reduce the risk of thromboembolism. Current data from both the Atrial Fibrillation Follow-up Investigation of Rhythm Management and Rate Control and Rhythm Control studies suggest cardioversion itself does not reduce the need for chronic warfarin to prevent clinical thromboembolism. Unfortunately, both electrical and pharmacological cardioversion may be associated with clinical thromboembolism, most often occurring during the first 10 days following conversion. For patients with hemodynamic instability, emergent direct current cardioversion is often performed. For hemodynamically stable patients with persistent AF for 2 days or more, there is a 6% risk of cardioversion-related clinical throm-boembolism if cardioversion is not preceded by several weeks of therapeutic (international normalization ratio [INR] 2.0-3.0) warfarin. The use of 3-4 wk of therapeutic warfarin before cardioversion results in an 80% reduction in clinical thromboembolic risk, to approx 1%.

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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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