The nurse is caring for a client with suspected infectious endocarditis. Which information obtained in the health history could contribute to the development of this problem?

A. the heart rate is greater than 100 bpm in sinus tachycardia: Normal Sinus Rhythm is characterized by a heart rate between 60 and 100 beats per minute (bpm). Sinus tachycardia is defined as a sinus rhythm with a heart rate exceeding 100 beats per minute. The rhythm remains regular, with each P wave followed by a QRS complex, but the rate is significantly faster than normal sinus rhythm.

B. more p waves are present than QRS complexes: In sinus tachycardia, the number of P waves and QRS complexes remains one-to-one, as each atrial impulse continues to be conducted to the ventricles. More P waves than QRS complexes typically suggest atrial flutter or other forms of AV dissociation.

C. the QRS complexes measure greater than 0.10: A widened QRS complex suggests a bundle branch block or ventricular rhythm, not sinus tachycardia. In sinus tachycardia, QRS complexes typically remain narrow, measuring less than 0.10 seconds unless an intraventricular conduction delay is present.

D. the rhythm is often irregular in sinus tachycardia: Sinus tachycardia is usually a regular rhythm with consistent R-R intervals. An irregular rhythm is more indicative of atrial fibrillation or sinus arrhythmia, not a defining characteristic of sinus tachycardia.

A. Hypermagnesemia: Hypermagnesemia (high magnesium levels) can cause bradycardia, hypotension, and prolonged PR and QRS intervals. While it can affect cardiac rhythm, it's less commonly associated with PVCs. The client's magnesium level of 2.5 mg/dL is within the normal range (1.5-2.5 mg/dL).

B. Hypocalcemia: While the calcium level of 8.0 mg/dL is slightly low (normal: ~8.5–10.5 mg/dL), mild hypocalcemia is less commonly associated with PVCs compared to hypokalemia. It can affect cardiac contractility but is not the most likely cause of these arrhythmias.

C. Hypokalemia: The potassium level is 2.8 mEq/L, which is significantly below normal (normal: 3.5–5.0 mEq/L). Potassium is a crucial electrolyte for maintaining normal cardiac electrical activity. Hypokalemia increases myocardial excitability and can lead to various cardiac dysrhythmias and a known cause of ventricular irritability, including multifocal PVCs, and increases the risk of life-threatening arrhythmias in clients with cardiac or metabolic conditions.

D. Hyperglycemia: The glucose level of 200 mg/dL is elevated but not severely high. While it reflects poor glycemic control, it is not directly linked to the occurrence of PVCs. Electrolyte imbalances, particularly low potassium, are more arrhythmogenic.