Which of the following studies would you anticipate to be ordered for your patient with valvular heart disease?

Choice A rationale:

In normal sinus rhythm, the sinoatrial node initiates each impulse, resulting in a P wave preceding every QRS complex. This indicates proper atrial depolarization followed by ventricular depolarization. The consistent presence of P waves before QRS complexes confirms intact conduction through the AV node and a functioning sinus node.

Choice B rationale

The T wave represents ventricular repolarization and should follow each QRS complex in a normal sinus rhythm. This sequence ensures the ventricles recover electrically before the next depolarization. Abnormal T wave morphology or timing may indicate ischemia, electrolyte imbalance, or other pathology. Normal T wave progression confirms healthy repolarization dynamics.

Choice C rationale

A QRS duration of 0.16 seconds exceeds the normal range of 0.06–0.10 seconds, suggesting intraventricular conduction delay or bundle branch block. Normal sinus rhythm requires a narrow QRS complex, indicating rapid and coordinated ventricular depolarization. Prolonged QRS duration is inconsistent with normal sinus rhythm and may reflect underlying conduction system disease.

Choice D rationale

A heart rate of 100–120 beats per minute is classified as sinus tachycardia, not normal sinus rhythm. Normal adult resting heart rate ranges from 60–100 beats per minute. Rates above 100 may be physiological (e.g., exercise, fever) or pathological (e.g., anemia, hyperthyroidism). Normal sinus rhythm requires a rate within the standard range.

Choice E rationale

The PR interval reflects conduction from the atria to the ventricles and should measure 0.12–0.20 seconds. This interval includes atrial depolarization and AV nodal delay. A normal PR interval confirms intact AV conduction. Shortened or prolonged PR intervals may indicate pre-excitation syndromes or AV block, respectively.

Choice A rationale

While chest pain (angina) is a serious complication often associated with reduced cardiac output from the rapid rate, especially in those with underlying coronary artery disease (CAD), managing the underlying rate is the most direct way to improve myocardial oxygen supply and demand balance, which is the cause of the pain.

Choice B rationale

Educating the patient is crucial for long-term management and preventing recurrence but is not the immediate, priority action for a patient presenting with an unstable, rapid ventricular response that significantly impairs cardiac output and could lead to cardiogenic shock or heart failure.

Choice C rationale

In atrial fibrillation with rapid ventricular response (RVR), the heart rate often exceeds 100 bpm, reducing the time for diastolic filling and thus significantly decreasing stroke volume and cardiac output. Therefore, the priority is to administer rate-controlling medications (e.g., beta-blockers, calcium channel blockers) to slow the ventricular response and stabilize hemodynamics.

Choice D rationale

Anticoagulation is essential to prevent systemic embolization and stroke risk due to stasis and clot formation in the fibrillating atria. However, it addresses a long-term risk and is not the immediate, life-saving priority over controlling the dangerously rapid heart rate that acutely compromises perfusion. —.