|
|
Sinus Tachycardia (tachy - fast)
- Sinus tachycardia occurs when the sinus rhythm is faster than 100 beats per minute. The
rhythm is similar to normal sinus rhythm with the exception that the RR interval is
shorter, less than 0.6 seconds. P waves are present and regular and each P-wave is
followed by a QRS complex in a ratio of 1:1. At very rapid rates, the P-waves might become
superimposed on the preceding T waves such that the P waves are obscured by T waves.
-
|
The EKG on the top shows normal
sinus rhythm. The EKG at the bottom shows sinus tachycardia |
|
|
|
|
-
- Sinus tachycardia may be accompanied by a decrease in stroke volume because
the ventricles do not have enough time to fill (after atrial systole)
before ventricular contraction.. The pulse pressure
may decrease due to a lower stroke volume and decreased time for diastolic run-off.
-
Sinus tachycardia results from increased automaticity of the SA node,
for instance, due to increased sympathetic stimulation of the heart, fever or cardiac
toxicity.
Back to top
Go to Quiz
-
|
