A 21-year-old Caucasian male presents to the emergency department following an episode of syncope.The syncopal episode was not provoked by any activity or circumstance. nor was it preceded by lightheadedness. The patient has no significant past medical history and he is not taking any medications.An ECG obtained in condition,the relevant mutation most likely affects which of the following structures?

A 37 -year-old woman with a longstanding diastolic murmur dies of a massive stroke. At autopsy, the following is found inside the left atrium:

A 4-year-old boy is brought in by his parents for evaluation of a fever that has persisted for the past 5 days. He has also been more irritable than usual and had 2 or 3 episodes of vomiting. The patient has no prior medical problems and takes no medications. He has received all recommended vaccinations. He traveled to China last year to visit his grandparents and cousins but has not traveled outside of the country this year. Temperature is 38.9 C (102 F). On physical examination, both conjunctivas are injected with no exudates. His tongue is bright red and lips are cracked. Nonpitting edema is present on his hands and feet. Which of the following complications is this patient at greatest risk for developing?

A 56-year-old man is admitted to a tertiary care center after being involved in a high-speed motor vehicle accident. He was thrown from his vehicle and suffered severe head trauma along with multiple fractures involving his ribs and extremities. Despite aggressive treatment, he dies from massive cerebral edema and brain herniation the following day. Autopsy shows increased thickness of the left ventricular wall and decreased left ventricular cavity size. The structural changes observed in this patient's heart are most likely associated with which of the following conditions?

A 55-year-old man comes to the physician complaining of progressive fatigue, dyspnea, and lower extremity edema. Several days ago, he had a slight fever, runny nose, and myalgias. He has no other past medical history and takes no medications. He has no family history of cardiomyopathy or sudden cardiac death. He drinks alcohol occasionally and does not use tobacco. Physica1 examination reveals jugular venous distention, crackles on lung auscultation, and 2+ pitting edema involving the lower extremities. After initial evaluation, the physician suspects dilated cardiomyopathy due to viral myocarditis. Which of the following hemodynamic findings would be most suggestive of an alternative diagnosis?

A 22-year-old woman comes to the physician complaining of worsening dyspnea. She has also experienced low-grade fevers, a 15-pound (6.8-kg) weight loss, and syncopal episodes over the last 3 months. Her shortness of breath worsens when sitting and improves when lying down. Her past medical history is insignificant. She does not smoke, drink alcohol, or use illicit drugs. Her temperature is 37.40 C (99.30 F), pulse is 75/min and regular, blood pressure is 115/72 mm Hg, and respirations are 12/min. Her lungs are clear. Cardiac auscultation reveals a low-pitched, mid-diastolic rumble at the cardiac apex. The remainder of her physical examination is normal. ECG reveals left atrial enlargement, and echocardiography shows a large pedunculated mass attached to the left atrium. Histologic analysis of this mass will most likely reveal which of the following?

A 75 year old Caucasian male presents to your office complaining of worsening dyspnea and fatigue on exertion. He adds that he has had several episodes of severe lightheadedness during physical activity recently. Physical examination reveals a harsh ejection-type systolic murmur at the base of the heart that radiates to the neck. You inform the patient that the most likely cause of his problem is:

A 50-year-old Caucasian female with a history of breast cancer treated by radical mastectomy and radiation several years ago, now presents with persistent right arm swelling. This patient is at increased risk of developing which of the following:

A 70-year-old Caucasian female presents to your office with back pain. Physical examination reveals local tenderness over two lumbar vertebrae, but no abnormal neurological findings. The woman's past medic a: history is non-contributory. She is not taking any medications, except an over-the-counter multivitamin X-ray findings are consistent with a vertebral compression fracture. Which of the following changes in bone structure is most likely responsible for this patient's condition?

A 68-year-old woman comes to the emergency department due to an acute vision disturbance. She had an episode of dimming of vision in the left eye that occurred abruptly and resolved spontaneously in 20 minutes. For the past several weeks, the patient has had a dull ache in the left side of her jaw while chewing that resolves when she stops eating. She has also had malaise and hip muscle aches over the last several months. The patient has a history of hypertension and hypothyroidism. On examination, her blood pressure is 130/70 mm Hg and pulse is 66/min. Neurological examination, including cranial nerves and motor and sensory functions, is unremarkable. Visual acuity, visual fields, and appearance of the ocular fundi are normal. Which of the following is the best initial test for this patient?