Which of the following describes status epilepticus? (Select all that apply.)

Choice A rationale

A ventricular pacemaker is designed to pace the ventricles, not the atria. Therefore, a pacemaker spike appearing before each P wave would indicate atrial pacing, which is not the primary function of a ventricular pacemaker. P waves represent atrial depolarization, and a ventricular pacemaker's stimulus is delivered to the ventricles to initiate a QRS complex.

Choice B rationale

A pacemaker spike appearing after each QRS complex suggests either oversensing, undersensing with competitive rhythms, or a malfunction. The purpose of a pacemaker spike is to *initiate* depolarization, not to follow it. If the spike occurs after the QRS, it indicates that the ventricle has already depolarized, and the spike is not contributing to ventricular contraction.

Choice C rationale

A pacemaker spike appearing with each T wave would be inappropriate and potentially dangerous. The T wave represents ventricular repolarization, a vulnerable period during which an electrical stimulus can induce life-threatening arrhythmias like ventricular fibrillation (R-on-T phenomenon). Pacing should occur before ventricular depolarization, not during repolarization.

Choice D rationale

A ventricular pacemaker functions by delivering an electrical impulse to the ventricle when its intrinsic rate falls below a programmed threshold. This impulse, seen as a pacemaker spike on the ECG, should precede ventricular depolarization, thus initiating a QRS complex. This indicates that the pacemaker is effectively stimulating ventricular contraction at the appropriate time.

Choice A rationale

Hypothyroidism, particularly if untreated, can contribute to bone loss, but levothyroxine therapy typically normalizes thyroid function, mitigating this risk. While age is a risk factor, other choices present more significant and direct risks for accelerated bone demineralization and osteoporosis development.

Choice B rationale

Estrogen plays a crucial role in bone density maintenance by inhibiting osteoclast activity and promoting osteoblast activity. A bilateral salpingo-oophorectomy removes the primary source of estrogen, leading to premature menopause and rapid bone loss, significantly increasing osteoporosis risk if hormone therapy is refused.

Choice C rationale

Prednisone, a corticosteroid, is a potent cause of secondary osteoporosis. It directly inhibits osteoblast function, promotes osteoclast activity, and impairs calcium absorption, leading to significant bone density loss. Long-term use post-transplant makes this patient at exceptionally high risk.

Choice D rationale

Excessive alcohol intake (more than 2-3 drinks daily) is a risk factor for osteoporosis by impairing bone formation and nutrient absorption. Limiting sun exposure can cause vitamin D deficiency, also contributing to reduced bone density. However, this patient's alcohol intake is moderate, and vitamin D deficiency is more easily corrected.