A 67-year-old man presents to the emergency department with acute onset of shortness of breath of 30 minutes' duration. Initially, he felt faint but did not lose consciousness. He is complaining of left-sided chest pain that increases on deep inspiration. He has no history of cardiopulmonary disease. A week ago, he underwent a total left hip replacement and, following discharge, was on bed rest for 5 days due to poorly controlled pain. He subsequently noticed swelling in his right calf, which is tender on examination. His current vital signs reveal a temperature of 38.0°C (100.4°F), heart rate of 112/min, blood pressure of 95/65 mm Hg, and an oxygen saturation on room air of 91%. Computerized tomography pulmonary angiography (CTPA) shows a partial intraluminal filling defect. Which of the following is the mechanism of this patient's illness?
Q332
A 29-year-old woman comes to the office with her husband because she has had 4 spontaneous abortions. Regarding her medical history, she was diagnosed with systemic lupus erythematosus 9 years ago, had a stroke 3 years ago, and was diagnosed with deep vein thrombosis in the same year. She has no relevant family history. Her vital signs include: heart rate 78/min, respiratory rate 14/min, temperature 37.5°C (99.5°F), and blood pressure 120/85 mm Hg. The physical examination is unremarkable. The complete blood count results are as follows:
Hemoglobin 12.9 g/dL
Hematocrit 40%
Leukocyte count 8,500/mm3
Neutrophils 55%
Bands 2%
Eosinophils 1%
Basophils 0%
Lymphocytes 29%
Monocytes 2%
Platelet count 422,000/mm3
Her coagulation test results are as follows:
Partial thromboplastin time (activated) 50.9 s
Prothrombin time 13.0 s
A VDRL test is done, and the result is positive. Mixing studies are performed, and they fail to correct aPTT. What is the most likely cause in this patient?
Q333
A 74-year-old woman presents to the clinic for evaluation of an erythematous and edematous skin rash on her right leg that has progressively worsened over the last 2 weeks. The medical history is significant for hypertension and diabetes mellitus type 2. She takes prescribed lisinopril and metformin. The vital signs include: blood pressure 152/92 mm Hg, heart rate 76/min, respiratory rate 12/min, and temperature 37.8°C (100.1°F). On physical exam, the patient appears alert and oriented. Observation of the lesion reveals a poorly demarcated region of erythema and edema along the anterior aspect of the right tibia. Within the region of erythema is a 2–3 millimeter linear break in the skin that does not reveal any serous or purulent discharge. Tenderness to palpation and warmth is associated with the lesion. There are no vesicles, pustules, papules, or nodules present. Ultrasound of the lower extremity is negative for deep vein thrombosis or skin abscess. The blood cultures are pending. Which of the following is the most likely diagnosis based on history and physical examination?
Q334
A 42-year-old woman comes to the physician for a routine health maintenance examination. She has generalized fatigue and has had difficulties doing her household duties for the past 3 months. She has eczema and gastroesophageal reflux disease. She has a history of using intravenous methamphetamine in her youth but has not used illicit drugs in 23 years. Her medications include topical clobetasol and pantoprazole. She is 160 cm (5 ft 3 in) tall and weighs 105 kg (231 lb); BMI is 42 kg/m2. Her temperature is 37°C (98.6°F), pulse is 95/min, and blood pressure is 145/90 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. Pelvic examination shows a normal vagina and cervix. Laboratory studies show:
Hemoglobin 13.1 g/dL
Leukocyte count 7,800/mm3
Platelet count 312,000/mm3
Serum
Na+ 141 mEq/L
K+ 4.6 mEq/L
Cl- 98 mEq/L
Urea nitrogen 12 mg/dL
Fasting glucose 110 mg/dL
Creatinine 0.8 mg/dL
Total cholesterol 269 mg/dL
HDL-cholesterol 55 mg/dL
LDL-cholesterol 160 mg/dL
Triglycerides 320 mg/dL
Urinalysis is within normal limits. An x-ray of the chest shows no abnormalities. She has not lost any weight over the past year despite following supervised weight loss programs, including various diets and exercise regimens. Which of the following is the most appropriate next step in management of this patient?
Q335
A 72-year-old man presents to the physician with a 3-month history of severe lower back pain and fatigue. The pain increases with activity. He has no history of any serious illness. He takes ibuprofen for pain relief. He does not smoke. His blood pressure is 105/65 mm Hg, pulse is 86/min, respiratory rate is 16/min, and temperature is 36.7°C (98.1°F). His conjunctivae are pale. Palpation over the 1st lumbar vertebra shows tenderness. Heart, lung, and abdominal examinations show no abnormalities. No lymphadenopathy is noted on palpation. Laboratory studies show:
Hemoglobin 9 g/dL
Mean corpuscular volume 90 μm3
Leukocyte count 5,500/mm3 with a normal differential
Platelet count 350,000/mm3
Serum
Calcium 11.5 mg/dL
Albumin 3.8 g/dL
Urea nitrogen 54 mg/dL
Creatinine 2.5 mg/dL
Lumbosacral X-ray shows an osteolytic lesion in the 1st lumbar vertebra and several similar lesions in the pelvic bone. Serum immunoelectrophoresis shows an IgG type monoclonal component of 40 g/L. Bone marrow plasma cells levels are at 20%. Which of the following is the most common cause of this patient’s acute renal condition?
Q336
A 48-year-old woman comes to the physician because of progressively worsening dyspnea on exertion and fatigue for the past 2 months. She had Hodgkin lymphoma as an adolescent, which was treated successfully with chemotherapy and radiation. Her father died from complications related to amyloidosis. She does not smoke or drink alcohol. Her temperature is 36.7°C (98°F), pulse is 124/min, respirations are 20/min, and blood pressure is 98/60 mm Hg. Cardiac examination shows no murmurs. Coarse crackles are heard at the lung bases bilaterally. An ECG shows an irregularly irregular rhythm with absent P waves. An x-ray of the chest shows globular enlargement of the cardiac shadow with prominent hila and bilateral fluffy infiltrates. Transthoracic echocardiography shows a dilated left ventricle with an ejection fraction of 40%. Which of the following is the most likely cause of this patient's condition?
Q337
A 23-year-old woman with no significant past medical history currently on oral contraceptive pills presents to the emergency department with pleuritic chest pain. She states that it started today. Yesterday she had a trip and returned via plane. Her temperature is 98°F (36.7°C), blood pressure is 117/66 mmHg, pulse is 105/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam reveals tachycardia, a normal S1 and S2, and clear breath sounds. The patient’s lower extremities are non-tender and symmetric. Chest pain is not reproducible with position changes or palpation but is worsened with deep breaths. Which of the following is the most appropriate next test for this patient?
Q338
A 79-year-old man with aortic stenosis comes to the emergency room because of worsening fatigue for 5 months. During this time, he has also had intermittent bright red blood mixed in with his stool. He has not had any abdominal pain or weight loss. Physical examination shows pale conjunctivae and a crescendo-decrescendo systolic murmur best heard at the second right intercostal space. The abdomen is soft and non-tender. Laboratory studies show a hemoglobin of 8 g/dL and a mean corpuscular volume of 71 μm3. Colonoscopy shows no abnormalities. Which of the following is the most likely underlying mechanism of this patient's bleeding?
Q339
A 68-year-old woman presents to the hospital for an elective right hemicolectomy. She is independently mobile and does her own shopping. She has had type 2 diabetes mellitus for 20 years, essential hypertension for 15 years, and angina on exertion for 6 years. She has a 30-pack-year history of smoking. The operation was uncomplicated. On post-op day 5, she becomes confused. She has a temperature of 38.5°C (101.3°F), respiratory rate of 28/min, and oxygen saturation of 92% on 2 L of oxygen. She is tachycardic at 118/min and her blood pressure is 110/65 mm Hg. On chest auscultation, she has coarse crackles in the right lung base. Her surgical wound appears to be healing well, and her abdomen is soft and nontender. Which of the following is the most likely diagnosis?
Q340
A 54-year-old man comes to the emergency department for nausea and vomiting for the past 2 days. The patient reports that he felt tired and weak for the past week without any obvious precipitating factors. Past medical history is significant for hypertension controlled with hydrochlorothiazide. He denies diarrhea, changes in diet, recent surgery, vision changes, or skin pigmentation but endorses a 10-lb weight loss, headaches, fatigue, and a chronic cough for 2 years. He smokes 2 packs per day for the past 20 years but denies alcohol use. Physical examination demonstrates generalized weakness with no peripheral edema. Laboratory tests are shown below:
Serum:
Na+: 120 mEq/L
Cl-: 97 mEq/L
K+: 3.4 mEq/L
HCO3-: 24 mEq/L
Ca2+: 10 mg/dL
Osmolality: 260 mOsm/L
Urine:
Na+: 25 mEq/L
Osmolality: 285 mOsm/L
Specific gravity: 1.007
What is the most likely finding in this patient?
Cardiology US Medical PG Practice Questions and MCQs
Question 331: A 67-year-old man presents to the emergency department with acute onset of shortness of breath of 30 minutes' duration. Initially, he felt faint but did not lose consciousness. He is complaining of left-sided chest pain that increases on deep inspiration. He has no history of cardiopulmonary disease. A week ago, he underwent a total left hip replacement and, following discharge, was on bed rest for 5 days due to poorly controlled pain. He subsequently noticed swelling in his right calf, which is tender on examination. His current vital signs reveal a temperature of 38.0°C (100.4°F), heart rate of 112/min, blood pressure of 95/65 mm Hg, and an oxygen saturation on room air of 91%. Computerized tomography pulmonary angiography (CTPA) shows a partial intraluminal filling defect. Which of the following is the mechanism of this patient's illness?
A. Trapped thrombus in the pulmonary vasculature (Correct Answer)
B. Occluding thrombus in a coronary artery
C. Accumulation of fluids in the pericardial sac
D. Inflammation of the lung parenchyma
E. Accumulation of air in the pericardial sac
Explanation: ***Trapped thrombus in the pulmonary vasculature***
- The patient's history of recent hip replacement, prolonged bed rest, and **right calf swelling and tenderness** strongly suggest **deep vein thrombosis (DVT)**, a major risk factor for subsequent **pulmonary embolism (PE)**.
- The acute onset of **shortness of breath**, **tachycardia**, **hypoxia**, and **pleuritic chest pain**, combined with **CTPA findings** of a partial intraluminal filling defect, confirms a pulmonary embolism caused by a trapped thrombus.
*Occluding thrombus in a coronary artery*
- This describes a **myocardial infarction (MI)**, which typically presents with substernal chest pain that may radiate, often associated with risk factors like atherosclerosis, none of which are explicitly highlighted for this patient’s acute presentation.
- While MI can cause shortness of breath and faintness, the pleuritic nature of the chest pain (increasing on inspiration) and the CTPA showing a filling defect in the pulmonary arteries point away from a primary cardiac event.
*Accumulation of fluids in the pericardial sac*
- This describes **pericardial effusion**, which can lead to **cardiac tamponade** if severe, causing hypotension, dyspnea, and muffled heart sounds.
- However, the patient's pleuritic chest pain and positive CTPA findings for a pulmonary embolus are not characteristic of pericardial effusion or tamponade.
*Inflammation of the lung parenchyma*
- This suggests **pneumonia** or **pneumonitis**, which would present with cough, fever, and crackles on lung auscultation, often with infiltrates on chest X-ray.
- While the patient has a low-grade fever, the abrupt onset of symptoms, pleuritic chest pain, and particularly the CTPA findings of a vascular filling defect are inconsistent with primary lung parenchymal inflammation.
*Accumulation of air in the pericardial sac*
- This refers to **pneumopericardium**, a rare condition that can cause chest pain and dyspnea, often associated with trauma, surgery, or barotrauma.
- The patient's symptoms and risk factors point clearly to a pulmonary embolism, and pneumopericardium would not typically present with a filling defect in the pulmonary vasculature on CTPA.
Question 332: A 29-year-old woman comes to the office with her husband because she has had 4 spontaneous abortions. Regarding her medical history, she was diagnosed with systemic lupus erythematosus 9 years ago, had a stroke 3 years ago, and was diagnosed with deep vein thrombosis in the same year. She has no relevant family history. Her vital signs include: heart rate 78/min, respiratory rate 14/min, temperature 37.5°C (99.5°F), and blood pressure 120/85 mm Hg. The physical examination is unremarkable. The complete blood count results are as follows:
Hemoglobin 12.9 g/dL
Hematocrit 40%
Leukocyte count 8,500/mm3
Neutrophils 55%
Bands 2%
Eosinophils 1%
Basophils 0%
Lymphocytes 29%
Monocytes 2%
Platelet count 422,000/mm3
Her coagulation test results are as follows:
Partial thromboplastin time (activated) 50.9 s
Prothrombin time 13.0 s
A VDRL test is done, and the result is positive. Mixing studies are performed, and they fail to correct aPTT. What is the most likely cause in this patient?
A. Antithrombin deficiency
B. Protein S deficiency
C. Protein C deficiency
D. Antiphospholipid syndrome (Correct Answer)
E. Factor V Leiden mutation
Explanation: ***Antiphospholipid syndrome***
- The patient's history of **recurrent spontaneous abortions**, **stroke**, **deep vein thrombosis**, and a **positive VDRL** (often falsely positive in APS) in the context of SLE strongly suggests antiphospholipid syndrome.
- The **prolonged aPTT** that **fails to correct** with mixing studies indicates the presence of a circulating anticoagulant, such as the lupus anticoagulant, which is characteristic of APS.
*Antithrombin deficiency*
- Antithrombin deficiency typically presents with a tendency for **thrombosis**, but it would **not cause recurrent abortions** or a **false-positive VDRL**.
- It would also **not affect aPTT** in the manner seen here (prolonged and unresponsive to mixing).
*Factor V Leiden mutation*
- **Factor V Leiden** is a common cause of **thrombophilia** and recurrent thrombosis. However, it is **not associated with recurrent abortions**, **false-positive VDRL**, or **prolonged aPTT**.
- This mutation leads to resistance to inactivation by protein C, increasing clot risk, but does not affect coagulation tests like aPTT in this specific way.
*Protein S deficiency*
- Protein S deficiency, like Factor V Leiden, is associated with an increased risk of **venous thrombosis**. However, it is **not directly linked to recurrent abortions** or a **false-positive VDRL**.
- It also does not typically cause a **prolonged aPTT** that fails to correct with mixing studies.
*Protein C deficiency*
- Protein C deficiency is a risk factor for **venous thrombosis** and can be associated with severe complications like **warfarin-induced skin necrosis**.
- Similar to other hereditary thrombophilias, it does **not explain the recurrent abortions**, **false-positive VDRL**, or the **specific aPTT findings** observed in this patient.
Question 333: A 74-year-old woman presents to the clinic for evaluation of an erythematous and edematous skin rash on her right leg that has progressively worsened over the last 2 weeks. The medical history is significant for hypertension and diabetes mellitus type 2. She takes prescribed lisinopril and metformin. The vital signs include: blood pressure 152/92 mm Hg, heart rate 76/min, respiratory rate 12/min, and temperature 37.8°C (100.1°F). On physical exam, the patient appears alert and oriented. Observation of the lesion reveals a poorly demarcated region of erythema and edema along the anterior aspect of the right tibia. Within the region of erythema is a 2–3 millimeter linear break in the skin that does not reveal any serous or purulent discharge. Tenderness to palpation and warmth is associated with the lesion. There are no vesicles, pustules, papules, or nodules present. Ultrasound of the lower extremity is negative for deep vein thrombosis or skin abscess. The blood cultures are pending. Which of the following is the most likely diagnosis based on history and physical examination?
A. Irritant contact dermatitis
B. Gas gangrene
C. Folliculitis
D. Erysipelas
E. Cellulitis (Correct Answer)
Explanation: **Cellulitis**
- The patient's presentation with a **poorly demarcated**, erythematous, and edematous rash on the lower leg, accompanied by warmth, tenderness, and a low-grade fever, is highly consistent with **cellulitis**. The linear skin break provides a potential port of entry for bacteria.
- Her history of **diabetes mellitus** is a significant risk factor for cellulitis due to impaired immune function and compromised peripheral circulation. The absence of vesicles or pustules further supports this diagnosis.
*Irritant contact dermatitis*
- This condition is typically characterized by **pruritus (itching)** and a rash that develops after exposure to an irritant, which is not described.
- While it can cause redness and edema, contact dermatitis usually does not present with significant **warmth**, tenderness, or fever.
*Gas gangrene*
- This is a severe, rapidly progressing infection characterized by **crepitus** (gas in the tissues), severe pain, and often a foul-smelling discharge, none of which are noted in the patient's presentation.
- The patient's symptoms are localized and do not suggest the systemic toxicity and rapid tissue necrosis associated with gas gangrene.
*Folliculitis*
- Folliculitis involves inflammation of hair follicles, presenting as small, **pustular lesions centered on hair follicles**, which are explicitly stated to be absent in this case.
- The extensive, diffuse erythema and edema described are not typical features of folliculitis.
*Erysipelas*
- Erysipelas is a superficial skin infection that typically presents with a **sharply demarcated**, raised border, unlike the "poorly demarcated" lesion described.
- While it shares some features with cellulitis (erythema, edema), the distinct border is a key differentiator, and erysipelas is also more likely to affect the face.
Question 334: A 42-year-old woman comes to the physician for a routine health maintenance examination. She has generalized fatigue and has had difficulties doing her household duties for the past 3 months. She has eczema and gastroesophageal reflux disease. She has a history of using intravenous methamphetamine in her youth but has not used illicit drugs in 23 years. Her medications include topical clobetasol and pantoprazole. She is 160 cm (5 ft 3 in) tall and weighs 105 kg (231 lb); BMI is 42 kg/m2. Her temperature is 37°C (98.6°F), pulse is 95/min, and blood pressure is 145/90 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. Pelvic examination shows a normal vagina and cervix. Laboratory studies show:
Hemoglobin 13.1 g/dL
Leukocyte count 7,800/mm3
Platelet count 312,000/mm3
Serum
Na+ 141 mEq/L
K+ 4.6 mEq/L
Cl- 98 mEq/L
Urea nitrogen 12 mg/dL
Fasting glucose 110 mg/dL
Creatinine 0.8 mg/dL
Total cholesterol 269 mg/dL
HDL-cholesterol 55 mg/dL
LDL-cholesterol 160 mg/dL
Triglycerides 320 mg/dL
Urinalysis is within normal limits. An x-ray of the chest shows no abnormalities. She has not lost any weight over the past year despite following supervised weight loss programs, including various diets and exercise regimens. Which of the following is the most appropriate next step in management of this patient?
A. Phentermine and topiramate therapy and follow-up in 3 months
B. Bariatric surgery (Correct Answer)
C. Liposuction
D. Behavioral therapy
E. Metformin and statin therapy and follow-up in 3 months
Explanation: ***Bariatric surgery***
- This patient has **severe obesity** (BMI of 42 kg/m²) with obesity-related comorbidities including **hypertension** (BP 145/90 mm Hg), **dyslipidemia** (elevated cholesterol and triglycerides), and **pre-diabetes** (fasting glucose 110 mg/dL), and has failed multiple supervised weight loss programs. **Bariatric surgery** is indicated for patients with BMI ≥ 40 kg/m² or BMI ≥ 35 kg/m² with obesity-related comorbidities who have failed at least 6 months of supervised weight loss.
- It is the most effective treatment for sustained weight loss in patients with **severe obesity**, leading to significant improvement or resolution of comorbidities.
*Phentermine and topiramate therapy and follow-up in 3 months*
- While medication can aid weight loss, this patient's **BMI of 42 kg/m²** signifies severe obesity, where medication alone is often insufficient for sustained and significant weight reduction.
- **Pharmacotherapy** is typically considered for BMI ≥ 30 kg/m² or BMI ≥ 27 kg/m² with comorbidities, but for class III obesity (BMI ≥ 40 kg/m²), bariatric surgery generally provides superior and more lasting outcomes.
*Liposuction*
- **Liposuction** is primarily a cosmetic procedure for localized fat removal and is not an effective treatment for generalized severe obesity or weight loss, nor does it address the metabolic complications of obesity.
- It does not lead to sustained weight loss or improvement in obesity-related comorbidities like **hypertension** and **dyslipidemia**.
*Behavioral therapy*
- The patient has already attempted multiple supervised weight loss programs, including various diets and exercise regimens, suggesting that **behavioral therapy** alone has not been effective for sustained weight loss in her case.
- While beneficial as part of a comprehensive approach, it is unlikely to achieve the significant and sustained weight loss required for a patient with **severe obesity** that has failed prior conventional methods.
*Metformin and statin therapy and follow-up in 3 months*
- **Metformin** and **statin therapy** target specific comorbidities (pre-diabetes/insulin resistance and dyslipidemia, respectively) but do not address the underlying **severe obesity**.
- While these medications are important for managing aspects of her metabolic syndrome, they are not a primary treatment for weight loss and will not lead to significant weight reduction in a patient with a **BMI of 42 kg/m²**.
Question 335: A 72-year-old man presents to the physician with a 3-month history of severe lower back pain and fatigue. The pain increases with activity. He has no history of any serious illness. He takes ibuprofen for pain relief. He does not smoke. His blood pressure is 105/65 mm Hg, pulse is 86/min, respiratory rate is 16/min, and temperature is 36.7°C (98.1°F). His conjunctivae are pale. Palpation over the 1st lumbar vertebra shows tenderness. Heart, lung, and abdominal examinations show no abnormalities. No lymphadenopathy is noted on palpation. Laboratory studies show:
Hemoglobin 9 g/dL
Mean corpuscular volume 90 μm3
Leukocyte count 5,500/mm3 with a normal differential
Platelet count 350,000/mm3
Serum
Calcium 11.5 mg/dL
Albumin 3.8 g/dL
Urea nitrogen 54 mg/dL
Creatinine 2.5 mg/dL
Lumbosacral X-ray shows an osteolytic lesion in the 1st lumbar vertebra and several similar lesions in the pelvic bone. Serum immunoelectrophoresis shows an IgG type monoclonal component of 40 g/L. Bone marrow plasma cells levels are at 20%. Which of the following is the most common cause of this patient’s acute renal condition?
A. Recurrent infections
B. Hypercalcemia (Correct Answer)
C. Nonsteroidal antiinflammatory drugs (NSAIDs)
D. Amyloid deposits
E. Infiltration of kidney by malignant cells
Explanation: ***Hypercalcemia***
- The patient exhibits several features of **multiple myeloma**, including osteolytic lesions, monoclonal gammopathy (IgG type, 40 g/L), and increased bone marrow plasma cells (20%).
- **Hypercalcemia** is a common complication of multiple myeloma due to increased bone resorption and is a significant cause of **acute kidney injury** through mechanisms like nephrogenic diabetes insipidus and renal vasoconstriction.
*Recurrent infections*
- While patients with multiple myeloma are prone to **recurrent infections** due to immunodeficiency, infections generally do not directly cause **acute renal failure** unless it is a severe systemic infection leading to sepsis and shock.
- There is no clinical evidence of a significant infection in this patient that would explain the acute renal condition.
*Nonsteroidal antiinflammatory drugs (NSAIDs)*
- **NSAIDs** can cause acute kidney injury, particularly in elderly patients or those with existing renal comorbidities, by inhibiting prostaglandin synthesis, leading to **afferent arteriolar vasoconstriction**.
- However, the patient's severe hypercalcemia due to multiple myeloma is a more direct and potent cause of acute renal injury in this context, making NSAID use less likely to be the primary cause.
*Amyloid deposits*
- **Amyloidosis**, specifically AL amyloidosis, is a known complication of multiple myeloma and can lead to **renal dysfunction** through amyloid deposition in the glomeruli and tubules.
- While relevant, amyloidosis typically causes a slower, progressive **chronic kidney disease** rather than an acute renal condition and would present with proteinuria (nephrotic syndrome), which is not mentioned here.
*Infiltration of kidney by malignant cells*
- Direct **infiltration of the kidneys by plasma cells** in multiple myeloma is a rare cause of renal failure in these patients.
- More common renal complications, like cast nephropathy (myeloma kidney) due to light chain deposition, are a more prevalent finding, but the presented data strongly points to hypercalcemia as the acute insult.
Question 336: A 48-year-old woman comes to the physician because of progressively worsening dyspnea on exertion and fatigue for the past 2 months. She had Hodgkin lymphoma as an adolescent, which was treated successfully with chemotherapy and radiation. Her father died from complications related to amyloidosis. She does not smoke or drink alcohol. Her temperature is 36.7°C (98°F), pulse is 124/min, respirations are 20/min, and blood pressure is 98/60 mm Hg. Cardiac examination shows no murmurs. Coarse crackles are heard at the lung bases bilaterally. An ECG shows an irregularly irregular rhythm with absent P waves. An x-ray of the chest shows globular enlargement of the cardiac shadow with prominent hila and bilateral fluffy infiltrates. Transthoracic echocardiography shows a dilated left ventricle with an ejection fraction of 40%. Which of the following is the most likely cause of this patient's condition?
A. Postradiation fibrosis
B. Coronary artery occlusion
C. Amyloid deposition
D. Acute psychological stress
E. Chronic tachycardia (Correct Answer)
Explanation: ***Chronic tachycardia***
- The **irregularly irregular rhythm with absent P waves** on ECG is characteristic of **atrial fibrillation**, which can lead to **tachycardia-induced cardiomyopathy** if sustained. The pulse of 124/min supports this.
- A sustained elevated heart rate like 124/min, especially in the context of atrial fibrillation, can cause **ventricular dilation** and reduced ejection fraction, leading to symptoms like dyspnea and fatigue observed in the patient.
*Postradiation fibrosis*
- While the patient has a history of radiation therapy for Hodgkin lymphoma, **radiation-induced cardiac damage** typically manifests as perivascular **fibrosis**, leading to **restrictive cardiomyopathy** or pericardial disease, not primarily dilated cardiomyopathy with an irregularly irregular rhythm.
- This condition is often associated with a **reduced diastolic filling** and **normal systolic function** initially, which contradicts the dilated left ventricle and reduced ejection fraction described.
*Amyloid deposition*
- The family history of amyloidosis is a red herring in this clinical picture. While **cardiac amyloidosis** can cause heart failure, it typically presents as **restrictive cardiomyopathy** with **thickened ventricular walls** and normal or reduced ventricular cavity size, not a dilated left ventricle.
- ECG findings in amyloidosis often include **low voltage QRS complexes** despite thickened walls, which is not described.
*Coronary artery occlusion*
- **Coronary artery occlusion** (e.g., myocardial infarction) can lead to dilated cardiomyopathy and reduced ejection fraction, but it usually presents with chest pain or specific ECG changes (e.g., ST elevation/depression, Q waves) that are not mentioned.
- The **irregularly irregular rhythm** (atrial fibrillation) and absence of murmurs make a primary ischemic event less likely as the sole explanation for the global cardiac changes.
*Acute psychological stress*
- **Acute psychological stress** can trigger **takotsubo cardiomyopathy** (stress-induced cardiomyopathy), which presents with left ventricular dysfunction and apical ballooning.
- However, this is typically an acute event with different ECG patterns (often ST elevation) and would not explain the chronic, sustained tachycardia and atrial fibrillation leading to dilated cardiomyopathy.
Question 337: A 23-year-old woman with no significant past medical history currently on oral contraceptive pills presents to the emergency department with pleuritic chest pain. She states that it started today. Yesterday she had a trip and returned via plane. Her temperature is 98°F (36.7°C), blood pressure is 117/66 mmHg, pulse is 105/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam reveals tachycardia, a normal S1 and S2, and clear breath sounds. The patient’s lower extremities are non-tender and symmetric. Chest pain is not reproducible with position changes or palpation but is worsened with deep breaths. Which of the following is the most appropriate next test for this patient?
A. D-dimer
B. Ultrasound of the lower extremities
C. Ventilation-perfusion scan
D. CT angiogram (Correct Answer)
E. Chest radiograph
Explanation: ***CT angiogram***
- This patient has **HIGH probability for pulmonary embolism (PE)** based on **Wells criteria**: oral contraceptive use (hypercoagulable state), recent long-haul flight (immobilization), pleuritic chest pain, and tachycardia (pulse 105/min).
- With a **Wells score ≥4**, the appropriate next step is **definitive imaging with CT pulmonary angiography (CTPA)**, which is the **gold standard** for diagnosing PE.
- **D-dimer should be bypassed** in high-probability cases, as a negative result would not adequately rule out PE, and a positive result (expected in high-probability patients) would require CTPA anyway.
- CTPA provides direct visualization of pulmonary arterial thrombi and can also identify alternative diagnoses.
*D-dimer*
- D-dimer is appropriate for **low to moderate probability PE** (Wells score <4) where a negative result can safely rule out PE and avoid unnecessary imaging.
- In this **high-probability case**, D-dimer is likely to be positive regardless, making it an unnecessary intermediate step that delays definitive diagnosis.
- Using D-dimer in high-probability patients can lead to false reassurance if negative or simply confirms the need for CTPA if positive.
*Ultrasound of the lower extremities*
- Lower extremity ultrasound diagnoses **deep vein thrombosis (DVT)**, not PE directly.
- While finding DVT in a patient with suspected PE would support anticoagulation, **absence of DVT does not rule out PE**, as thrombi may have already embolized.
- This would delay appropriate diagnosis and is not the most direct test for suspected PE.
*Ventilation-perfusion scan*
- V/Q scan is reserved for patients with **contraindications to CT contrast** (severe renal insufficiency, contrast allergy) or pregnant patients where radiation exposure should be minimized.
- This young patient has no mentioned contraindications to contrast-enhanced CT.
- V/Q scanning is less specific than CTPA and often yields indeterminate results.
*Chest radiograph*
- Chest X-ray is often **normal in PE** or shows non-specific findings (Westermark sign, Hampton's hump are rare).
- While it may help exclude alternative diagnoses like pneumothorax or pneumonia, it cannot definitively diagnose or rule out PE.
- In a patient with high clinical suspicion for PE, delaying CTPA to obtain a chest X-ray is not optimal management.
Question 338: A 79-year-old man with aortic stenosis comes to the emergency room because of worsening fatigue for 5 months. During this time, he has also had intermittent bright red blood mixed in with his stool. He has not had any abdominal pain or weight loss. Physical examination shows pale conjunctivae and a crescendo-decrescendo systolic murmur best heard at the second right intercostal space. The abdomen is soft and non-tender. Laboratory studies show a hemoglobin of 8 g/dL and a mean corpuscular volume of 71 μm3. Colonoscopy shows no abnormalities. Which of the following is the most likely underlying mechanism of this patient's bleeding?
A. Thrombus in the superior mesenteric artery
B. Tortuous submucosal blood vessels (Correct Answer)
C. Atherosclerotic narrowing of the mesenteric arteries
D. Inherited factor VIII deficiency
E. Transmural inflammation of the large bowel
Explanation: ***Tortuous submucosal blood vessels***
- This patient's presentation of **aortic stenosis** and **gastrointestinal bleeding** (bright red blood in stool, IDA) is highly suggestive of **Heyde's syndrome**.
- Heyde's syndrome is characterized by the association between aortic stenosis and gastrointestinal bleeding due to **angiodysplasia**, which are tortuous submucosal blood vessels prone to bleeding. The pathophysiology involves acquired **von Willebrand factor deficiency** due to high shear stress across the diseased aortic valve, leading to degradation of large von Willebrand factor multimers, which normally help platelet adhesion at sites of bleeding.
*Thrombus in the superior mesenteric artery*
- A **superior mesenteric artery (SMA) thrombus** typically presents with sudden onset, severe abdominal pain, often disproportionate to physical exam findings, and signs of bowel ischemia (e.g., bloody diarrhea late in the course).
- This patient has chronic, intermittent bleeding and fatigue without acute abdominal pain, making SMA thrombosis unlikely.
*Atherosclerotic narrowing of the mesenteric arteries*
- **Chronic mesenteric ischemia** due to atherosclerotic narrowing often causes **postprandial abdominal pain** (intestinal angina), fear of eating, and weight loss, which are absent here.
- While it can lead to ischemic colitis and bleeding, the primary presentation is typically pain related to food intake.
*Inherited factor VIII deficiency*
- **Hemophilia A** (Factor VIII deficiency) typically causes deep tissue bleeding, hemarthroses, and bleeding after trauma or surgery. It is a congenital disorder, usually presenting much earlier in life.
- It is unlikely to present as new-onset, intermittent GI bleeding in an elderly patient without a prior history of bleeding disorders.
*Transmural inflammation of the large bowel*
- **Transmural inflammation of the large bowel** is characteristic of **Crohn's disease**, which often presents with abdominal pain, diarrhea (sometimes with blood), weight loss, and systemic symptoms.
- The patient denies abdominal pain or weight loss, and the colonoscopy showed no abnormalities, ruling out inflammatory bowel disease.
Question 339: A 68-year-old woman presents to the hospital for an elective right hemicolectomy. She is independently mobile and does her own shopping. She has had type 2 diabetes mellitus for 20 years, essential hypertension for 15 years, and angina on exertion for 6 years. She has a 30-pack-year history of smoking. The operation was uncomplicated. On post-op day 5, she becomes confused. She has a temperature of 38.5°C (101.3°F), respiratory rate of 28/min, and oxygen saturation of 92% on 2 L of oxygen. She is tachycardic at 118/min and her blood pressure is 110/65 mm Hg. On chest auscultation, she has coarse crackles in the right lung base. Her surgical wound appears to be healing well, and her abdomen is soft and nontender. Which of the following is the most likely diagnosis?
A. Malignant hyperthermia
B. Drug-induced fever
C. Multiple organ dysfunction syndrome
D. Sepsis (Correct Answer)
E. Non-infectious systemic inflammatory response syndrome (SIRS)
Explanation: ***Sepsis***
- The patient exhibits several signs of **systemic inflammatory response syndrome (SIRS)** (fever, tachycardia, tachypnea) coupled with evidence of infection (coarse crackles in the lung base suggests **pneumonia**).
- The combination of **SIRS criteria** and a likely infection source in a postoperative patient strongly points to sepsis, a life-threatening organ dysfunction caused by a dysregulated host response to infection.
*Malignant hyperthermia*
- This is a rare, life-threatening condition typically triggered by **volatile anesthetic agents** or **succinylcholine** during surgery.
- It usually presents **intraoperatively or immediately postoperatively** with rapid onset of hyperthermia, muscle rigidity, and metabolic acidosis, which is not consistent with a presentation on post-op day 5.
*Drug-induced fever*
- While drug-induced fever is possible, particularly in polymedicated patients, it would be a **diagnosis of exclusion** when other more likely causes of fever, such as infection, are present.
- There are no specific clinical features in this case that strongly suggest a drug as the singular cause of fever and the systemic inflammatory response.
*Multiple organ dysfunction syndrome*
- **MODS** is the progressive failure of two or more organ systems and is often a **complication of severe sepsis or septic shock**, rather than an initial diagnosis.
- While the patient is unwell, her current presentation describes a potential precursor (sepsis) rather than established multi-organ dysfunction.
*Non-infectious systemic inflammatory response syndrome (SIRS)*
- SIRS caused by non-infectious etiologies (e.g., pancreatitis, trauma, burns) can occur, but the presence of **localized lung crackles** and a **postoperative fever** makes an infectious etiology much more likely.
- Postoperative SIRS can occur due to surgical stress, but the signs of infection (especially respiratory) shift the diagnosis towards sepsis.
Question 340: A 54-year-old man comes to the emergency department for nausea and vomiting for the past 2 days. The patient reports that he felt tired and weak for the past week without any obvious precipitating factors. Past medical history is significant for hypertension controlled with hydrochlorothiazide. He denies diarrhea, changes in diet, recent surgery, vision changes, or skin pigmentation but endorses a 10-lb weight loss, headaches, fatigue, and a chronic cough for 2 years. He smokes 2 packs per day for the past 20 years but denies alcohol use. Physical examination demonstrates generalized weakness with no peripheral edema. Laboratory tests are shown below:
Serum:
Na+: 120 mEq/L
Cl-: 97 mEq/L
K+: 3.4 mEq/L
HCO3-: 24 mEq/L
Ca2+: 10 mg/dL
Osmolality: 260 mOsm/L
Urine:
Na+: 25 mEq/L
Osmolality: 285 mOsm/L
Specific gravity: 1.007
What is the most likely finding in this patient?
A. Antibodies against presynaptic calcium channels
B. Pituitary hypertrophy
C. Chromogranin positive mass in the lung (Correct Answer)
D. Venous congestion at the liver
E. Orphan Annie eyes and psammoma bodies in the thyroid
Explanation: ***Chromogranin positive mass in the lung***
- The patient presents with **hyponatremia**, **low serum osmolality (260 mOsm/L)**, and **inappropriately high urine osmolality (285 mOsm/L)** and urine sodium (25 mEq/L), which are characteristic findings of the **Syndrome of Inappropriate Antidiuretic Hormone (SIADH)**.
- While **hydrochlorothiazide can cause hyponatremia**, the patient's **20-pack-year smoking history**, **chronic cough for 2 years**, **weight loss**, and **fatigue** strongly suggest an underlying malignancy rather than simple medication effect.
- The most likely cause of SIADH in this patient is **small cell lung carcinoma (SCLC)**, which is a **neuroendocrine tumor** that commonly secretes ADH ectopically and stains positive for **chromogranin A**, a neuroendocrine marker.
- SCLC is the most common malignancy associated with SIADH and frequently presents with paraneoplastic syndromes in heavy smokers.
*Antibodies against presynaptic calcium channels*
- This finding is characteristic of **Lambert-Eaton myasthenic syndrome (LEMS)**, which is a paraneoplastic syndrome associated with small cell lung cancer caused by antibodies against voltage-gated calcium channels.
- While LEMS can occur in patients with SCLC, the presented symptoms and laboratory findings (specifically euvolemic hyponatremia consistent with SIADH) point more directly to **ectopic ADH secretion** from the tumor rather than a neuromuscular disorder.
- LEMS typically presents with proximal muscle weakness that improves with repeated use, which is not described in this patient.
*Pituitary hypertrophy*
- **Pituitary adenomas** can cause various endocrine abnormalities, but they do not typically cause SIADH.
- SIADH from pituitary pathology is rare and would not explain the **pulmonary symptoms** (chronic cough) or the patient's **significant smoking history**.
- This does not fit the overall clinical picture as well as small cell lung carcinoma.
*Venous congestion at the liver*
- **Hepatic venous congestion** occurs in conditions like right-sided heart failure, constrictive pericarditis, or Budd-Chiari syndrome.
- The patient has **no signs of volume overload** (no peripheral edema, and exam shows generalized weakness only).
- While heart failure can cause hyponatremia, it typically presents with hypervolemic hyponatremia with signs of fluid overload, which is absent in this case.
*Orphan Annie eyes and psammoma bodies in the thyroid*
- These are characteristic histological features of **papillary thyroid carcinoma**.
- There is **no clinical evidence** of thyroid pathology (e.g., thyroid nodule, neck mass, dysphagia, hoarseness) in this patient.
- Papillary thyroid carcinoma is not associated with SIADH or the paraneoplastic syndromes seen in this case.
