Sinus Bradycardia in Cats

A slower-than-normal rate of impulses in the sinus node is medically referred to as sinus bradycardia (SB). Also called the sinoatrial node (SAN), the sinus node initiates the electrical impulses within the heart, triggering the heart to beat or contract. In most instances, slow sinus electrical impulses is benign and may even be beneficial; however, it can also cause loss of consciousness if it is brought about by an underlying disease that disrupts the cardiac autonomic nerves, which act as the heart's control system.

SB is less common in cats as compared to dogs. Moreover, the rate of the heartbeat will depend on the environment a size of the animal.

Symptoms and Types 

Your cat may display no symptoms if it very active or engaging in athletic training. Typically, the sinus bradycardia (heartbeat slower than 120 beats per minute, although depends on the animal's environment and size) is most apparent when your cat is at rest. Some other common symptoms associated with sinus bradycardia include:

• Lethargy
• Seizures
• Exercise intolerance
• Loss of consciousness
• Episodic muscle incoordination (ataxia)
• Excessively slow breathing (hypoventilation), especially under anesthesia

Causes

• Athletic conditioning (this is not uncommon in athletic cats)
• Hypothermia
• Intubation
• Oversedation
• Sleep
• Underlying disease(s); e.g., respiratory, neurologic, and gastronintestinal diseases