Irregular Heart Beat in Dogs

Ventricular premature complexes (VPCs) are extra, abnormal heartbeats that begin in one of heart's two lower pumping chambers (ventricles). These extra beats disrupt regular heart rhythm. These extra and abnormal heartbeats are a type of irregular heart beat. 

The heart is made up of four chambers. Upper two chambers are called left and right atria and bottom two chambers are called left and right ventricles. Heart valves are present between right atrium and ventricle, left atrium and ventricle, from right ventricle to the main pulmonary (lung) artery and from left ventricle to aorta (main artery of body).

To pump the blood to the body and lungs, the heart needs to work in a coordinated fashion. It has an electrical conduction system which generates electrical impulses which propogate throughout the heart to stimulate muscles which contract and push the blood into the arteries and out into the body. Two nodes of the heart play an important role in this conduction system. One is sinus node, or sinoatrial (SA) node, which is a clustered collection of similar cells located in the right atrium. The other is the atrioventricular (AV) node, located in right artium near ventricle. Normal control or pacemaker of the heart is sinoatrial (SA) node. It starts electrical impulse that causes contraction of atria so that blood is pumped into ventricles. The AV node receives the impulse and after a small delay, that allows atrium to eject blood into the ventricle, directs the impulse to the ventricles. The pulse moves into vetnricles causing contraction and pumping of blood into lungs (right ventricle) and the body (left ventricle).

Ventricular premature complexes are a type of irregular heart beat where the electrical impulse is initiated in the ventricles instead of SA node. This results in too early (premature) contraction of the ventricles before they are filled with blood from atrium. Too early contraction of the ventricles results in less blood being pumped to the body and concurrently, less oxygen for the body organs.  

On an electrocardiogram (ECG), these irregular heart beats are denoted by too wide or oddly shaped QRS complexes. 

Common symptoms associated with Ventricular Premature Complexes (VPC) include 


Exercise intolerance


Often asymptomatic

Cough if caused by congestive heart failure (CHF)

Difficulty breathing if caused by CHF

Sudden death

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