ECG from a 9 yo MN doberman pinscher with a history of dilated cardiomyopathy

HR 240bpm, irregularly irregular, lack of p waves but presence of baseline f waves, narrow QRS complexes of varying amplitudes.

Remember that for a paper speed of 25mm/s, one small square = 0.04s and one large square = 0.2s. Count the number of QRS complexes over 30 large squares, or 6s (I count 24 here). Multiply this number by 10 to get bpm (24 beats per 6 seconds = 240 beats per 60 seconds). Another trick is to use a Bic Biro (lid on) which is roughly 150mm or 6s long when held against a 25mm/s strip. Count the complexes and multiply by 10 to get HR in bpm.

Atrial fibrillation

Diltiazem is a benzodiazepine calcium channel blocker that suppresses AV nodal conduction, SA nodal automaticity and cardiac contractility as well as causing vasodilation. The aim of diltiazem treatment in atrial fibrillation is to reduce the ventricular response rate.

Bradycardia, hypotension and gastrointestinal upset