Sinus Tachycardia

Sinus tachycardia is a sinus rhythm with an increased sinus nodal rate, and therefore ventricular rate.

• Dog (<20 kg) with heart rate >180 bpm
• Dog (>20 kg) with heart rate >160 bpm
• Cat with heart rate >240 bpm

Examples of etiologies include:

1. Pain
2. Fever
3. Anemia
4. Hypovolemia
5. Reduced cardiac output (and resultant hypotension)
6. Hyperthyroidism
7. Excitement or stress

Consequences:

1. If HR is excessive, cardiac output may fall due to reduced diastolic filling time
2. Coronary perfusion decreases, also due to shorter diastole
3. Increased myocardial oxygen consumption per beat
4. The above are generally only significant if sustained for long period of time

Treatment: Treat the underlying cause.