Sinus Tachycardia with a Dash of Premature Extopic Complex

I went in for an Electrocardiogram a couple weeks ago and I received my results today. Healthy as a horse, except that my heart rate is high (105 BPM). Here is what my ECG should look like:

…And here is what my ECG is (actually this one isn’t mine, but it shows sinus tachycardia):

From: http://sprojects.mmi.mcgill.ca/cardiophysio/sinustachycardia.htm

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.

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.