Answer to Question 1
A
Treatment for sinus tachycardia is directed at correcting the underlying cause (i.e., fluid replacement, relief of pain, removal of offending medications or substances, reducing fever or anxiety). Sinus tachycardia in a patient experiencing an acute myocardial infarction (MI) may be treated with medications to slow the heart rate and decrease myocardial oxygen demand (e.g., beta-blockers), provided there are no signs of heart failure or other contraindications.
Answer to Question 2
B
Characteristics of sinus rhythm:
Rhythm R-R and P-P intervals are regular
Rate 60 to 100 beats/min
P waves Positive (upright) in lead II; one precedes each QRS complex; P waves look alike
PR interval 0.12 to 0.20 seconds and constant from beat to beat
QRS duration 0.11 seconds or less unless abnormally conducted