Page 15 - VetCPD Jnl Volume 7, Issue 4

VETcpd - Cardiology
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Video 2: Right parasternal long axis four chamber view in a patient with lone atrial fibrillation. There is no obvious underlying structural cardiac disease. The ventricular rate varies between 113-120 bpm. Link: www.bit.ly/2UCiysJ
AB
Figure 5:
(A) Dog with atrial fibrillation wearing a Holter monitor;
(B) Holter monitor
Treatment
There are two different therapeutic approaches to manage AF: rate control or rhythm control.
This decision should be based on each individual patient, depending mainly on clinical signs, underlying structural heart disease and arrhythmia duration (Pariaut, 2017).The clinician should also keep
in mind that AF is commonly seen in association with CHF and, if so, concurrent symptomatic CHF treatment is mandatory.
Rhythm control
Rhythm control strategy results in conversion of AF to sinus rhythm. Physiologically, this is beneficial for the patient as it provides a better cardiac output (due to the contribution of the active atrial contraction) and avoids the progressive atrial remodeling that can be caused by the arrhythmia itself. However, despite improved cardiac function, rhythm control is not always the appropriate choice for all patients (see below).
Video 1: Right parasternal long axis four chamber view in a patient with fast atrial fibrillation, dilated cardiomyopathy and congestive heart failure. The left ventricle is rounded and the left atrium is dilated. Please note the fast ventricular rate, which may give the false appearance of regular rhythm.
Link: www.bit.ly/32Q9iWz
of choice, either intravenously as a bolus or as a continuous rate infusion, or an oral loading protocol (Oyama and Prosek, 2006; Saunders et al. 2006; Pedro et
al. 2012).The success rate is only 35% (Bright et al. 2005; Saunders et al. 2006), but a reduction in ventricular response rate is commonly achieved, and therefore it may be beneficial despite this (Saunders et al. 2006; Pedro et al. 2012; Sanders
et al. 2014).When given intravenously, the previously available formulation (Cordarone) was associated with serious risks of anaphylactic reaction, requiring pre-medication with antihistamines
or corticosteroids (although drug discontinuation was frequently required). A new formulation is now available (Nexterone), which lacks the solvent responsible for the anaphylaxis and is therefore safer.When cardioversion is achieved, oral amiodarone administration is usually continued long-term, requiring close monitoring of thyroid and hepatic function due to potential toxicity (Pedro et al. 2012). Lidocaine can also be used to convert rare episodes of vagally mediated AF if acute onset (Pariaut et al. 2008), but this is ineffective for long standing cases.
OnlyFor pharmacological cardioversion, amiodarone is the anti-arrhythmic drug
When the patient is considered a candidate
for cardioversion, this can be achieved in
two ways: either electrically – or
pharmacologically – mediated.
Pharmacological cardioversion