Atrial fibrillation and flutter US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Atrial fibrillation and flutter. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Atrial fibrillation and flutter US Medical PG Question 1: A 21-year-old woman presents with palpitations and anxiety. She had a recent outpatient ECG that was suggestive of supraventricular tachycardia, but her previous physician failed to find any underlying disease. No other significant past medical history. Her vital signs include blood pressure 102/65 mm Hg, pulse 120/min, respiratory rate 17/min, and temperature 36.5℃ (97.7℉). Electrophysiological studies reveal an atrioventricular nodal reentrant tachycardia. The patient refuses an ablation procedure so it is decided to perform synchronized cardioversion with consequent ongoing management with verapamil. Which of the following ECG features should be monitored in this patient during treatment?
- A. Amplitude and direction of the T wave
- B. Length of QRS complex
- C. Length of QT interval
- D. Length of PR interval (Correct Answer)
- E. QRS complex amplitude
Atrial fibrillation and flutter Explanation: ***Length of PR interval***
- Verapamil is a **non-dihydropyridine calcium channel blocker** that primarily acts on the **AV node** to slow conduction.
- Monitoring the **PR interval** is crucial because excessive slowing of AV nodal conduction can lead to **AV block**, which is indicated by a prolonged PR interval.
*Amplitude and direction of the T wave*
- Changes in T-wave amplitude and direction are often associated with **myocardial ischemia** or **electrolyte imbalances**, which are not the primary concerns with verapamil.
- While verapamil can affect repolarization, the most direct and common adverse effect related to its mechanism of action on the AV node is not primarily reflected in T-wave changes.
*Length of QRS complex*
- The QRS complex duration primarily reflects **ventricular depolarization** and is typically affected by medications that alter conduction through the His-Purkinje system or within the ventricles, such as antiarrhythmics like **flecainide** or **amiodarone**.
- Verapamil's main action is on the AV node, so it generally does not significantly prolong the QRS complex unless there is pre-existing conduction system disease.
*Length of QT interval*
- The QT interval represents **ventricular repolarization**, and its prolongation can lead to **Torsades de Pointes**, a life-threatening arrhythmia.
- While many antiarrhythmics can prolong the QT interval, **verapamil is not known to significantly prolong the QT interval** and is generally considered safe in this regard.
*QRS complex amplitude*
- Changes in QRS amplitude can indicate conditions like **pericardial effusion**, **cardiomyopathy**, or changes in ventricular mass.
- These are generally not direct or common side effects of verapamil therapy, which primarily focuses on AV nodal conduction.
Atrial fibrillation and flutter US Medical PG Question 2: A 75-year-old man presents to the emergency department after an episode of syncope while walking outside with his wife. His wife states that he suddenly appeared pale and collapsed to the ground. She says he remained unconscious for 1 minute. He says he noticed a fluttering in his chest and excessive sweating before the episode. He has type 2 diabetes mellitus, essential hypertension, and chronic stable angina. He has not started any new medications in the past few months. Vital signs reveal: temperature 37.0°C (98.6°F), blood pressure 135/72 mm Hg, and pulse 72/min. Physical examination is unremarkable. ECG shows an old bifascicular block. Echocardiogram and 24-hour Holter monitoring are normal. Which of the following is the best next step in the evaluation of this patient's condition?
- A. Cardiac enzymes
- B. Continuous loop recorder (Correct Answer)
- C. Valsalva maneuver
- D. Electroencephalography (EEG)
- E. Tilt-table test
Atrial fibrillation and flutter Explanation: ***Continuous loop recorder***
- This patient's syncope is preceded by **palpitations (fluttering in chest)** and **sweating**, suggesting a cardiac etiology, specifically a **transient arrhythmia** not captured on a standard ECG or 24-hour Holter.
- A continuous loop recorder provides prolonged monitoring (months to years), increasing the likelihood of detecting intermittent arrhythmias responsible for syncopal episodes.
*Cardiac enzymes*
- While cardiac enzymes (e.g., troponin) are crucial for evaluating **acute myocardial ischemia** or infarction, the patient presents with syncope and no new chest pain, and his stable angina suggests chronic disease rather than an acute event leading to syncope in this specific instance.
- An **ECG showing an old bifascicular block** and an **unremarkable physical exam** make an acute cardiac event less likely as the primary cause of syncope when an arrhythmia is suspected.
*Valsalva maneuver*
- The Valsalva maneuver is a diagnostic tool often used to differentiate between certain types of **tachyarrhythmias** or to evaluate for **autonomic dysfunction**, but it is not an evaluative step for a patient presenting with unexplained syncope where an arrhythmia has not yet been documented.
- It would not help in identifying the cause of intermittent syncope in a patient whose standard workup has been unremarkable, as it's a test for immediate physiological response, not prolonged cardiac rhythm monitoring.
*Electroencephalography (EEG)*
- EEG is indicated when **seizure disorder** is suspected as the cause of loss of consciousness, often characterized by tonic-clonic movements, post-ictal confusion, or focal neurologic signs, which are absent in this patient's presentation.
- The patient's pre-syncopal symptoms of **palpitations and sweating** point away from a seizure and towards a cardiac cause.
*Tilt-table test*
- A tilt-table test is used to evaluate for **vasovagal syncope** or **postural orthostatic tachycardia syndrome (POTS)**, often considered when other cardiac causes are ruled out or when syncope is typically triggered by prolonged standing.
- Given the patient's pre-syncopal **palpitations**, a **cardiac arrhythmia** remains a higher suspicion than vasovagal syncope at this stage, especially after normal echocardiogram and Holter monitoring, necessitating further arrhythmia investigation.
Atrial fibrillation and flutter US Medical PG Question 3: A 26-year-old nursing home staff presents to the emergency room with complaints of palpitations and chest pain for the past 2 days. She was working at the nursing home for the last year but has been trying to get into modeling for the last 6 months and trying hard to lose weight. She is a non-smoker and occasionally drinks alcohol on weekends with friends. On examination, she appears well nourished and is in no distress. The blood pressure is 150/84 mm Hg and the pulse is 118/min. An ECG shows absent P waves. All other physical findings are normal. What is the probable diagnosis?
- A. Anorexia nervosa
- B. Graves' disease
- C. Hashimoto thyroiditis
- D. Toxic nodular goiter
- E. Factitious thyrotoxicosis (Correct Answer)
Atrial fibrillation and flutter Explanation: ***Factitious thyrotoxicosis***
- The patient's profession as a nursing home staff member provides access to medications, and her attempts to lose weight for modeling suggest a motive for **self-administration of thyroid hormones**.
- **Absent P waves** on ECG along with **palpitations and tachycardia** are consistent with atrial arrhythmias often seen in thyrotoxicosis, but the overall presentation with a desire for weight loss points towards an exogenous source.
*Anorexia nervosa*
- While patients with anorexia nervosa do try to lose weight, their presentation is typically associated with **bradycardia**, not the tachycardia and elevated blood pressure seen here.
- ECG findings in anorexia nervosa would more likely show **QT prolongation** or other conduction abnormalities due to electrolyte imbalances, not specifically absent P waves caused by arrhythmia.
*Graves' disease*
- Graves' disease is an autoimmune condition causing hyperthyroidism, presenting with similar symptoms like **tachycardia and palpitations**. However, it is typically associated with other systemic findings such as **ophthalmopathy (exophthalmos)**, **pretibial myxedema**, or a palpable goiter, none of which are mentioned.
- Laboratory findings would show **high T3/T4** with **low TSH**, and often **positive TSH receptor antibodies**, differentiating it from factitious causes.
*Hashimoto thyroiditis*
- Hashimoto thyroiditis is an **autoimmune cause of hypothyroidism**, characterized by fatigue, weight gain, and bradycardia, which are opposite to the patient's symptoms of palpitations, tachycardia, and weight loss efforts.
- While it can initially present with transient hyperthyroidism (hashitoxicosis), the chronic state is hypothyroidism, and the ECG would not typically show absent P waves.
*Toxic nodular goiter*
- A toxic nodular goiter causes hyperthyroidism due to **autonomous thyroid nodules**, leading to symptoms similar to Graves' disease (palpitations, weight loss).
- However, the physical examination would usually reveal a **palpable nodular goiter**, which is not mentioned in this case, making it a less likely diagnosis compared to factitious thyrotoxicosis given the context.
Atrial fibrillation and flutter US Medical PG Question 4: A 50-year-old man with a history of atrial fibrillation presents to his cardiologist’s office for a follow-up visit. He recently started treatment with an anti-arrhythmic drug to prevent future recurrences and reports that he has been feeling well and has no complaints. The physical examination shows that the arrhythmia appears to have resolved; however, there is now mild bradycardia. In addition, the electrocardiogram recording shows a slight prolongation of the PR and QT intervals. Which of the following drugs was most likely used to treat this patient?
- A. Metoprolol
- B. Sotalol (Correct Answer)
- C. Propranolol
- D. Verapamil
- E. Carvedilol
Atrial fibrillation and flutter Explanation: ***Sotalol***
- **Sotalol** is a **beta-blocker** and a **Class III antiarrhythmic** drug, meaning it blocks potassium channels.
- This dual action explains the **bradycardia** (beta-blockade) and the **prolongation of the PR and QT intervals** (potassium channel blockade), which are characteristic side effects.
*Metoprolol*
- **Metoprolol** is a **selective beta-1 blocker** (Class II antiarrhythmic) that would cause **bradycardia** and **PR prolongation**, but it does not typically prolong the **QT interval**.
- It primarily affects the heart rate and AV nodal conduction without significant potassium channel blocking properties.
*Propranolol*
- **Propranolol** is a **non-selective beta-blocker** (Class II antiarrhythmic) that would cause **bradycardia** and **PR prolongation**.
- Similar to metoprolol, it does not typically prolong the **QT interval**.
*Verapamil*
- **Verapamil** is a **non-dihydropyridine calcium channel blocker** (Class IV antiarrhythmic) that causes **bradycardia** and **PR prolongation**.
- However, it does not prolong the **QT interval**; instead, it can sometimes shorten it.
*Carvedilol*
- **Carvedilol** is a **non-selective beta-blocker** with **alpha-1 blocking properties** (Class II antiarrhythmic), leading to **bradycardia** and **PR prolongation**.
- It does not have effects on potassium channels that would lead to **QT prolongation**.
Atrial fibrillation and flutter US Medical PG Question 5: A 70-year-old male presents for an annual exam. His past medical history is notable for shortness of breath when he sleeps, and upon exertion. Recently he has experienced dyspnea and lower extremity edema that seems to be worsening. Both of these symptoms have resolved since he was started on several medications and instructed to weigh himself daily. Which of the following is most likely a component of his medical management?
- A. Lidocaine
- B. Verapamil
- C. Carvedilol (Correct Answer)
- D. Aspirin
- E. Ibutilide
Atrial fibrillation and flutter Explanation: ***Carvedilol***
- The patient exhibits classic symptoms of **heart failure**, such as **dyspnea on exertion**, **orthopnea** (shortness of breath when he sleeps), and **lower extremity edema**.
- **Beta-blockers** like carvedilol are essential for managing **chronic heart failure** by reducing myocardial oxygen demand and improving cardiac function.
*Lidocaine*
- **Lidocaine** is primarily an **antiarrhythmic drug** used for acute treatment of **ventricular arrhythmias**, not for chronic heart failure management.
- It works by blocking sodium channels and has no direct benefit in addressing the underlying pathophysiology of heart failure.
*Verapamil*
- **Verapamil** is a **non-dihydropyridine calcium channel blocker** typically used for hypertension, angina, and supraventricular tachyarrhythmias.
- It can have **negative inotropic effects**, which are generally contraindicated or used with extreme caution in patients with **systolic heart failure** due to its potential to worsen cardiac function.
*Aspirin*
- **Aspirin** is an **antiplatelet agent** used for primary or secondary prevention of **atherosclerotic cardiovascular disease** (e.g., in patients with coronary artery disease).
- It does not directly manage the symptoms or pathophysiology of **heart failure** unless there is a coexisting ischemic etiology.
*Ibutilide*
- **Ibutilide** is an **antiarrhythmic drug** specifically used for the rapid conversion of **atrial flutter and atrial fibrillation** of recent onset to sinus rhythm.
- It is not a medication used for the long-term management of **heart failure** symptoms described in the patient.
Atrial fibrillation and flutter US Medical PG Question 6: A 65-year-old man with hypertension and paroxysmal atrial fibrillation presents to his cardiologist for follow-up after recently starting metoprolol for rate control. His EKG shows an atrial rate of 260/min with ventricular rate of 50/min on an irregular baseline. An echocardiogram from his previous visit revealed no evidence of hypokinesis or hypertrophy with functionally intact valves. The patient does not drink alcohol and had no evidence of liver dysfunction in prior studies. What is the best medication for rhythm control in this patient?
- A. Amiodarone
- B. Flecainide (Correct Answer)
- C. Procainamide
- D. Verapamil
- E. Mexiletine
Atrial fibrillation and flutter Explanation: ***Flecainide***
- **Flecainide** is a **Class IC antiarrhythmic** medication that is effective for rhythm control in patients with **paroxysmal atrial fibrillation** and no structural heart disease.
- The patient's echocardiogram showed no evidence of hypokinesis or hypertrophy, with functionally intact valves, indicating the **absence of structural heart disease**, which is a prerequisite for using Class IC agents like flecainide.
*Amiodarone*
- **Amiodarone** is a potent antiarrhythmic but is associated with numerous significant **extracardiac side effects**, including **pulmonary fibrosis**, **thyroid dysfunction**, and liver toxicity.
- It is generally reserved for patients with structural heart disease or those who have failed other antiarrhythmic therapies due to its extensive side effect profile.
*Procainamide*
- **Procainamide** is a **Class IA antiarrhythmic** that has a high incidence of side effects, including **drug-induced lupus**, and is typically used for acute management of arrhythmias, not long-term rhythm control in this setting.
- Its use is limited by its short half-life and significant proarrhythmic potential, especially in patients with structural heart disease or LV dysfunction.
*Verapamil*
- **Verapamil** is a **non-dihydropyridine calcium channel blocker** primarily used for **rate control** in atrial fibrillation, not rhythm control.
- The patient is already on metoprolol for rate control, and the question specifically asks for a medication for rhythm control.
*Mexiletine*
- **Mexiletine** is a **Class IB antiarrhythmic** agent primarily used for treating **ventricular arrhythmias**, particularly in the setting of myocardial infarction.
- It is not typically used for rhythm control in atrial fibrillation and has limited efficacy in this context.
Atrial fibrillation and flutter US Medical PG Question 7: A 44-year-old woman comes to the physician because of progressively worsening shortness of breath with exertion and intermittent palpitations over the last 2 months. She has had neither chest pain nor a cough. Her pulse is 124/min and irregular. Physical examination shows a grade 4/6 high-pitched holosystolic murmur that is best heard at the apex and radiates to the back. The murmur increases in intensity when she clenches her hands into fists. The lungs are clear to auscultation. Further evaluation of this patient is most likely to show which of the following findings?
- A. Obstruction of the right marginal artery on coronary angiogram
- B. Diffuse ST elevations on electrocardiogram
- C. Dilation of left atrium on echocardiogram (Correct Answer)
- D. Reversible area of myocardial ischemia on nuclear stress test
- E. Pulmonary artery thrombus on computed tomography scan
Atrial fibrillation and flutter Explanation: ***Dilation of left atrium on echocardiogram***
- The patient's symptoms of **shortness of breath**, **palpitations**, and an **irregular pulse** suggest a cardiac etiology, specifically a **valvular problem**. The **holosystolic murmur** best heard at the **apex** and radiating to the **back**, which increases with handgrip (a maneuver that increases afterload), is highly characteristic of **mitral regurgitation**.
- **Chronic mitral regurgitation** leads to **volume overload** in the left atrium, causing its **dilation** as it tries to accommodate the increased blood flow from both the pulmonary veins and the regurgitant jet from the left ventricle. This can also lead to **atrial fibrillation**, explaining the irregular pulse and palpitations.
*Obstruction of the right marginal artery on coronary angiogram*
- This finding would indicate **coronary artery disease** affecting the right coronary artery, typically presenting with **chest pain** or angina, which the patient explicitly denies.
- While coronary artery disease can cause shortness of breath, the distinctive **holosystolic murmur** and its radiation are not primary features of isolated coronary artery obstruction.
*Diffuse ST elevations on electrocardiogram*
- **Diffuse ST elevations** are typically seen in conditions like **pericarditis**, which often presents with pleuritic chest pain and a pericardial friction rub, none of which are described.
- It could also indicate an ST-elevation myocardial infarction (STEMI), but the 2-month history and the specific murmur point away from an acute coronary event.
*Reversible area of myocardial ischemia on nuclear stress test*
- This would suggest **ischemic heart disease**, again primarily indicated by **angina** or exertional chest discomfort, which is absent in this patient.
- While ischemia can cause shortness of breath and palpitations, it does not explain the characteristic **holosystolic murmur** and its specific radiation.
*Pulmonary artery thrombus on computed tomography scan*
- A **pulmonary artery thrombus** (pulmonary embolism) would typically cause **acute dyspnea**, pleuritic chest pain, and sometimes hemoptysis, which are not mentioned.
- While it can cause palpitations and an irregular pulse (due to right heart strain), it does not account for the **holosystolic murmur** heard at the apex and radiating to the back.
Atrial fibrillation and flutter US Medical PG Question 8: A 63-year-old woman presents to the primary care physician’s clinic complaining of fatigue, diarrhea, headaches, and a loss of appetite. She denies any personal history of blood clots in her past, but she says that her mother has also had to be treated for pulmonary embolism in the recent past. Her past medical history is significant for preeclampsia, hypertension, polycystic ovarian syndrome, and hypercholesterolemia. She currently smokes 1 pack of cigarettes per day, drinks a glass of wine per day, and she currently denies any illicit drug use, although she has a remote past of injection drug use with heroin. The vital signs include: temperature 36.7°C (98.0°F), blood pressure 126/74 mm Hg, heart rate 111/min and irregular, and respiratory rate 17/min. On physical examination, her pulses are bounding and complexion is pale, but breath sounds remain clear. Oxygen saturation was initially 91% on room air and electrocardiogram (ECG) showed atrial fibrillation. Upon further discussion with the patient, her physician discovers that she is having some cognitive difficulty. The laboratory results reveal: mean corpuscular volume (MCV) 111 fL; hemoglobin (Hgb) 9.3 g/dL; methylmalonic acid (MMA) and homocysteine are both elevated. Schilling test is positive. What is the next best step in the management of this patient?
- A. Lifelong Vitamin B12 supplementation (Correct Answer)
- B. Obtain a Coomb’s test
- C. Lifelong folic acid supplementation
- D. Give corticosteroids and iron supplementation
- E. Iron supplementation for 4–6 months
Atrial fibrillation and flutter Explanation: ***Lifelong Vitamin B12 supplementation***
- The patient's **macrocytic anemia** (MCV 111 fL, Hgb 9.3 g/dL), elevated methylmalonic acid (MMA) and homocysteine, and a positive Schilling test strongly indicate **pernicious anemia**, a form of **Vitamin B12 deficiency** due to inadequate intrinsic factor.
- **Pernicious anemia** requires lifelong Vitamin B12 supplementation, usually via intramuscular injections due to impaired absorption.
- The **elevated MMA** is particularly specific for B12 deficiency (as opposed to folate deficiency, which does not elevate MMA).
*Obtain a Coombs test*
- A **Coombs test** is used to detect antibodies that coat red blood cells, which is relevant in **autoimmune hemolytic anemia**.
- The patient's clinical picture, particularly the elevated MMA/homocysteine and positive Schilling test, points away from **hemolytic anemia** and towards **Vitamin B12 deficiency**.
*Lifelong folic acid supplementation*
- While **folic acid deficiency** can also cause **macrocytic anemia** and elevated homocysteine, it does **not** cause elevated MMA.
- Supplementing with **folic acid alone** in the presence of **Vitamin B12 deficiency** can mask the hematological symptoms while allowing neurological damage to progress.
*Give corticosteroids and iron supplementation*
- **Corticosteroids** are typically used in conditions like **autoimmune hemolytic anemia** or other autoimmune diseases, which are not suggested by the lab results.
- **Iron supplementation** is indicated for **iron-deficiency anemia**, which presents with **microcytic** or **normocytic anemia**, not the **macrocytic anemia** seen here.
*Iron supplementation for 4–6 months*
- This intervention is appropriate for **iron-deficiency anemia**, which is characterized by **microcytic anemia** and low ferritin/iron levels.
- The patient's **macrocytic anemia** and elevated MMA/homocysteine rule out **iron-deficiency anemia** as the primary issue.
Atrial fibrillation and flutter US Medical PG Question 9: A 42-year-old woman comes to the physician because of 2 episodes of loss of consciousness over the past week. She recovered immediately and was not confused following the episodes. During the past 5 months, she has also had increased shortness of breath and palpitations. She has been unable to carry out her daily activities. She also reports some chest tightness that resolves with rest. She has no history of serious illness and takes no medications. She immigrated with her family from India 10 years ago. Her temperature is 37.3°C (99.1°F), pulse is 115/min and irregular, and blood pressure is 108/70 mm Hg. Examination shows jugular venous distention and pitting edema below the knees. Bilateral crackles are heard at the lung bases. Cardiac examination shows an accentuated and split S2. There is an opening snap followed by a low-pitched diastolic murmur in the fifth left intercostal space at the midclavicular line. An ECG shows atrial fibrillation and right axis deviation. Which of the following is the most likely underlying mechanism of these findings?
- A. Increased left ventricular end diastolic pressure
- B. Increased left to right shunting
- C. Increased systemic arterial resistance
- D. Increased left atrial pressure (Correct Answer)
- E. Decreased left ventricular contractility
Atrial fibrillation and flutter Explanation: ***Increased left atrial pressure***
- The patient's symptoms (dyspnea, palpitations, chest tightness, volume overload signs like JVD, edema, crackles) and cardiac findings (**accentuated S2, opening snap, diastolic murmur**) are highly suggestive of **mitral stenosis**.
- **Mitral stenosis** causes obstruction of blood flow from the left atrium to the left ventricle, leading to a significant increase in **left atrial pressure** to maintain cardiac output, which can then cause atrial fibrillation and pulmonary hypertension.
*Increased left ventricular end diastolic pressure*
- This is typically seen in conditions like **aortic stenosis**, **aortic regurgitation**, or **decompensated heart failure** where the left ventricle is distended or failing.
- The patient's presentation with an **opening snap** and **diastolic murmur** points away from primary left ventricular pathology causing elevated LVEDP, and more towards a valvular issue upstream.
*Increased left to right shunting*
- This typically occurs in **septal defects** (e.g., VSD, ASD, PDA) and would lead to symptoms of pulmonary hypertension and right heart strain, but the specific murmur and opening snap are not characteristic of a shunt.
- While it can cause right ventricular hypertrophy and pulmonary hypertension, the classic auscultatory findings are distinct from those described here.
*Increased systemic arterial resistance*
- This is characteristic of **hypertension** or conditions causing systemic vasoconstriction, which primarily affect afterload on the left ventricle.
- While it can lead to left ventricular hypertrophy over time, it does not explain the specific findings of an **opening snap** and **diastolic murmur**, or the symptoms of pulmonary congestion in this context.
*Decreased left ventricular contractility*
- This would lead to **systolic heart failure** with reduced ejection fraction, causing symptoms like fatigue and dyspnea, and often a **S3 gallop** with a systolic murmur if mitral regurgitation develops.
- However, it does not explain the specific auscultatory findings of an **opening snap** and **diastolic murmur** that are pathognomonic for mitral stenosis.
Atrial fibrillation and flutter US Medical PG Question 10: A 72-year-old man presents to the ED complaining of worsening abdominal pain over the last few hours. He also reports nausea, but denies fever, vomiting, or changes in the appearance of his bowel movements. His medical history is significant for type 2 diabetes mellitus, hypertension, coronary artery disease, stroke, atrial fibrillation, and peptic ulcer disease. Due to his recurrent bleeding peptic ulcers, he does not take warfarin. His surgical history is significant for an appendectomy as a child. His medications include metformin, lisinopril, metoprolol, and omeprazole. He has a 50-pack-year history of smoking. His temperature is 37.6 C (99.7 F), blood pressure is 146/80 mm Hg, pulse is 115/min, and respiratory rate is 20/min. On physical exam, he is in acute distress due to the pain. Pulmonary auscultation reveals scattered wheezes and decreased air entry. His heart rate is irregularly irregular, with no murmurs, rubs or gallops. Abdominal exam is significant for decreased bowel sounds and diffuse tenderness. Initial laboratory evaluation is as follows:
Na 138 mEq/L, Cl 101 mEq/L, HCO3 12 mEq/L, BUN 21 mg/dL, Cr 0.9 mg/dL, glucose 190 mg/dL, amylase 240 U/L (normal < 65 U/L).
What is the most likely diagnosis in this patient?
- A. Acute cholecystitis
- B. Peptic ulcer perforation
- C. Acute mesenteric ischemia (Correct Answer)
- D. Diabetic ketoacidosis
- E. Acute pancreatitis
Atrial fibrillation and flutter Explanation: ***Acute mesenteric ischemia***
- The patient has multiple risk factors for **mesenteric ischemia**, including **atrial fibrillation** (predisposing to emboli), **coronary artery disease, stroke**, and **smoking history**. Critically, he is **not anticoagulated** despite AF due to bleeding ulcers, significantly increasing embolic risk.
- The **acute onset of severe abdominal pain out of proportion to physical exam findings** (diffuse tenderness, decreased bowel sounds) in a patient with these risk factors is highly suggestive of mesenteric ischemia.
- The **lactic acidosis** (indicated by HCO3 of 12 mEq/L) and elevated pulse rate are consistent with **ischemic bowel**, as tissue hypoxia leads to anaerobic metabolism and lactate production.
- **Elevated amylase can occur in mesenteric ischemia** due to bowel wall hypoxia and increased intestinal permeability.
*Acute cholecystitis*
- Characterized by **right upper quadrant pain**, **Murphy's sign**, **fever**, and often **vomiting**, which are not present in this patient.
- The diffuse abdominal tenderness and strong vascular risk factors point away from this diagnosis.
*Peptic ulcer perforation*
- Typically presents with **sudden onset, severe, diffuse abdominal pain** with a **rigid, board-like abdomen** (peritonitis signs) and often **free air on imaging**.
- While the patient has a history of peptic ulcer disease, the absence of peritoneal signs like rigidity and the presence of significant vascular disease with lactic acidosis make mesenteric ischemia more likely.
*Diabetic ketoacidosis*
- Characterized by **hyperglycemia**, **anion gap metabolic acidosis**, **ketonemia/ketonuria**, and often **vomiting** and **altered mental status**.
- Although there is hyperglycemia (190 mg/dL) and metabolic acidosis, this glucose level is not high enough for DKA (typically >250 mg/dL), and the absence of vomiting, mental status changes, and ketonuria make this unlikely.
- The severity of acidosis (HCO3 12) with only modest hyperglycemia suggests **lactic acidosis** from tissue ischemia rather than DKA.
*Acute pancreatitis*
- Typically presents with **epigastric pain radiating to the back**, often associated with **nausea and vomiting**.
- While the amylase is elevated at 3.7 times the upper limit of normal (which meets diagnostic criteria), **amylase elevation can also occur in mesenteric ischemia** due to intestinal hypoxia and increased permeability.
- The **clinical context strongly favors ischemia**: multiple vascular risk factors, pain out of proportion to exam, severe lactic acidosis, and lack of typical pancreatitis features (epigastric/back pain pattern).
- The profound metabolic acidosis (HCO3 12) is more severe than typically seen in uncomplicated pancreatitis and suggests tissue ischemia.
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