Page 52 - Rapid Review of ECG Interpretation in Small Animal Practice, 2nd Edition

Section 5

VetBooks.ir HOLTER MONITORING

The diagnosis of intermittently occurring cardiac DEVICES AVAILABLE FOR
arrhythmias is challenging and typically requires CONTINUOUS AMBULATORY ECG
ambulatory electrocardiography. Holter monitoring MONITORING
refers to ambulatory electrocardiogram (ECG) The most commonly available device for short-
recording of the heart rate and rhythm over a term (24 h to 48 h) continuous monitoring is the
prolonged period of time, ideally while the patient Holter, worn externally with a vest (Fig. 5.1) for
is in the familiar home environment and performs the duration of the recording, providing a three-
normal activities. lead ECG recording. It can be cumbersome for cat
It is an important part of the diagnosis, screening, patients and of limited utility when longer-term
management, and prognosticating of arrhythmias. monitoring is desirable (infrequent arrhythmias).
Even if a rhythm diagnosis is suspected based on the Modern digital systems are quite small and light
identification of occasional abnormal beats on an (Figs. 5.2, 5.3, 5.5, and 5.6) and secured on the
in-hospital ECG, a Holter monitor offers the best animals back using specially designed vests or
assessment of overall frequency and complexity of jackets, as well as adhesive bandages.
the arrhythmia and presents an important guide for For infrequent arrhythmia capture, event
monitoring treatment. monitors—also known as implantable loop recorders
may be advantageous. They can continually record and
HOLTER INDICATIONS overwrite a short section of a single-lead ECG trace.
Subcutaneously implanted systems are smaller than a
• History of collapse or exercise intolerance— triple-A battery (Fig. 5.4) and capable of monitoring
suspect sporadic arrhythmias up to 3 years. Placed on the left hemithorax under
• Quantitation of arrhythmia burden of
intermittent arrhythmias diagnosed by
in-hospital ECGs
• Monitoring of drug efficacy—e.g., suppression
of ventricular arrhythmias or ventricular rate
control in atrial fibrillation
• Screening for arrhythmias in apparently healthy
dogs of predisposed breeds at risk for cardiac
disease

Fig. 5.1 Holter recorder, secured on dog with a
specially designed vest where the monitor is carried
in a pouch on the back.

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