A 10-year-old female domestic short-haired cat presented with a 5-month history of episodes of 'incoordination' of increasing frequency. These episodes were reported to be more frequent after some minor stress or mild exertion. Neurological examination was unremarkable.

This cat’s heart rate was 180-220 depending upon the degree of underlying stress. When lifted onto the table for examination, the cat had an episode as shown in the video below, and the heart rate dropped to 80 before suddenly increasing to 180. ECG confirmed a third-degree (complete) heart block with no ventricular escape rhythm for several seconds and no pulse at all during these periods. Subsequently, the ECG demonstrated an unstable irregular ventricular escape rhythm for approximately 10 seconds before reverting to a normal sinus rhythm. Blood pressure, routine blood work and echocardiography were normal.

Diagnosis was collapse secondary to intermittent complete heart block and the cat was treated with a pacemaker.

Remember to consider the evaluation of the cardiovascular system, especially in cases with paroxysmal dysfunction. Click on the link below to read more about cats exhibiting paroxysmal events with cardiac arrhythmias (atrioventricular block).

Courtesy of Drs Anna Tauro and Emily Dutton.