Veterinary Medicine - January 2008 - (Page 32)

Holter monitors PEER-REVIEWED 1. Selected Holter monitor ECG rhythm strips demonstrating ventricular tachycardia in a Doberman pinscher. pinschers and boxers be examined by cardiac ultrasonography and Holter recording once a year (Figure 1). Determining the atrial ﬁbrillation ventricular response rate Atrial brillation is a common disorder in dogs and is usually associated with advanced heart disease. Often by the time atrial brillation is detected by an ECG, it is a persistent, rapid, and irregular heart rhythm. Rate control, rather than rhythm control, is a common management strategy for dogs with atrial brillation. When dogs are examined in the hospital setting, particularly during restraint for diagnostic testing, their sympathetic nervous system activity may be increased. Sympathetic dominance decreases the refractory period of the AV nodal tissue and increases its conductivity. For this reason, when a static ECG is performed in a dog being treated for atrial brillation, the ventricular response rate to the brillating atria is increased compared with when the patient is calm.21 Holter recording in the home environment allows accurate measurement of the post-treatment heart rate characteristics over a 24-hour period in a natural setting. In most patients, the heart rates in the home setting are signi cantly slower than in the hospital (Figure 2).21 When a dog being treated for atrial brillation is re-examined in the hospital setting and the static ECG reveals an atrial brillation ventricular response rate > 180 beats/min, it may be necessary to add an additional drug to the treatment regimen to reduce the ventricular rate. In patients with cardiac disease, our goal for atrial brillation is a ventricular response rate in the home environment < 140 beats/min for 90% of the 24-hour Holter monitoring period. Assessing the functional integrity of implanted artiﬁcial cardiac pacemakers Pacemaker implantation is the recommended treatment for dogs with symptomatic bradyarrhythmias unresponsive to anticholinergics. In dogs with permanent arti cial cardiac pacemakers, periodically con rm normal pacemaker function. Evaluation can be performed by using a computerized program system analyzer. Holter recording can also provide information about pacemaker function, such as quanti cation of normal rhythm vs. paced rhythm time, sensitivity of the rate-responsive feature to activity levels, and appropriateness of inhibition to spontaneous ectopic activity. Because of the limited examination time during routine hospital visits and the pacemaker’s limited ability to store abnormal ECG recordings, a Holter 32 January 2008 VETERINARY MEDICINE

Table of Contents Feed for the Digital Edition of Veterinary Medicine - January 2008

Veterinary Medicine - January 2008 Contents Digital Extra Letters Toxicology Brief Idea Exchange A Challenging Case: Phimosis in a Young Adult Dog The Indications and Technique for Continuous Ambulatory Electrocardiographic Recording in Dogs A Review of Selected Systemic Antifungal Drugs for Use in Dogs and Cats CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - January 2008

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