Ventricular premature contractions (VPCs) are premature heart beats that originate in the lower chambers of the heart (the ventricles) rather than in the normal pacemaker of the heart (the sinus node). In many dogs, VPCs are due to underlying heart disease so an echocardiogram is recommended when a diagnosis of ventricular arrhythmia is made. Other causes of VPCs in dogs include electrolyte or metabolic derangements (which are diagnosed via blood work), intra-abdominal disease (usually diagnosed via abdominal x-rays and/or abdominal ultrasound) and severe systemic diseases.
Ventricular arrhythmias are less common in cats, but they are usually due to underlying heart disease, so an echocardiogram is strongly recommended.
If no correctable cause for a ventricular arrhythmia is identified, a Holter monitor is recommended – this is a monitor that records 24 hours of a dog’s heart rate and rhythm in his/her normal environment. The results of the Holter monitor help determine if anti-arrhythmic medications are necessary.
Infrequent, single VPCs do not cause any clinical compromise and usually do not require treatment. Frequent VPCs and VPCs that occur in runs at a rapid rate (ventricular tachycardia) may lead to weakness, collapse and even sudden death. Various anti-arrhythmic medications are available for animals with significant ventricular arrhythmia. Follow-up generally involves periodic recheck ECGs and Holter monitors.
Dogs or cats that have been diagnosed with ventricular arrhythmia should be monitored closely for sudden weakness (difficulty rising, stumbling), collapse episodes, loss of consciousness, cold limbs, pale gums, labored breathing, increased resting breathing rate, worsening exercise intolerance, vomiting or abdominal distension. If any of these signs are seen, your pet needs to be evaluated by a veterinarian right away.