As mentioned at the beginning of this chapter, the heart rate in sinus tachycardia is greater than 100 BPM. Generally, it is between 101 and 160 BPM in most patients. At this rate, the tachycardia itself does not pose any significant problems. The heart rate of the rhythm can, however, go up to 200 BPM and maybe even as high as 220 BPM in rare circumstances. At these rates, the rhythm can pose both clinical and diagnostic challenges. We will discuss the differential diagnosis of wide complex tachycardias in Chapter 36, Wide-Complex Tachycardia: Criteria. For now, we will concentrate on the typical forms that are not as difficult to identify.
In general, the maximum heart rate that can be considered normal for any individual patient is derived by using the formula:
Maximum Heart Rate = 220 BPM − Age (years)
For example, a 20-year-old man has a maximum heart rate of 200 BPM (220 BPM − 20 years = 200 BPM). Anything above that level would be considered abnormal and would require further evaluation.
The maximum heart rate is usually reached during exercise or forced activity of some kind. Athletes and young people are able to tolerate the high levels without difficulty. Elderly patients or patients with some cardiac pathology cannot tolerate levels near their maximum heart rate without some difficulty. Luckily, many patients never get to their maximum levels because they have some disease in their electrical conduction system that limits the rate they can reach.
ARRHYTHMIA RECOGNITION
Sinus Tachycardia
| Rate: | > 100 BPM |
| Regularity: | Regular |
| P wave:
Morphology: Upright in II, III, and aVF: |
Present
Same Yes |
| P:QRS ratio: | 1:1 |
| PR interval: | Normal, consistent |
| QRS width: | Normal or wide |
| Grouping: | None |
| Dropped beats: | None |
DIFFERENTIAL DIAGNOSIS
Sinus Tachycardia