Catheter ablation procedures US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Catheter ablation procedures. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Catheter ablation procedures US Medical PG Question 1: A 44-year-old man comes to the emergency department because of persistent palpitations for the past 2 hours. The day before, he was at a wedding, where he drank several glasses of wine and 9–10 vodka cocktails. He has never had similar symptoms before. He is a manager at a software company and has recently had a lot of work-related stress. He is otherwise healthy and takes no medications. His temperature is 36.5°C (97.7°F), pulse is 90/min and irregularly irregular, respirations are 13/min, and his blood pressure is 128/60 mm Hg. Physical examination shows no other abnormalities. An ECG is performed; no P-waves can be identified. Echocardiography shows no valvular abnormalities and normal ventricular function. One hour later, a repeat ECG shows normal P waves followed by narrow QRS complexes. He is still experiencing occasional palpitations. Which of the following is the most appropriate next step in management?
- A. Electrical cardioversion
- B. Defibrillation
- C. Adenosine injection
- D. Observation (Correct Answer)
- E. Catheter ablation
Catheter ablation procedures Explanation: ***Observation***
- The patient experienced **paroxysmal atrial fibrillation (AF)** likely triggered by **binge alcohol consumption** (holiday heart syndrome), which has already spontaneously converted to normal sinus rhythm.
- Given his hemodynamic stability, normal ventricular function, and the transient nature of this isolated episode, **close observation** for recurrence is the most appropriate initial step.
*Electrical cardioversion*
- This is primarily used for **hemodynamically unstable AF** or for persistent AF that fails to convert spontaneously.
- The patient is currently **hemodynamically stable** and has already converted to normal sinus rhythm, making cardioversion unnecessary.
*Defibrillation*
- **Defibrillation** is used for life-threatening arrhythmias like **ventricular fibrillation** or **pulseless ventricular tachycardia**.
- It is not indicated for stable atrial fibrillation, and the patient has already converted to sinus rhythm.
*Adenosine injection*
- **Adenosine** is used to terminate **supraventricular tachycardias (SVTs)** by blocking the AV node.
- It is generally **ineffective for atrial fibrillation** and not indicated here as the patient is already in normal sinus rhythm.
*Catheter ablation*
- **Catheter ablation** is a definitive treatment for recurrent symptomatic AF or other arrhythmias that are refractory to medical management.
- This patient has experienced a **first-time episode** that spontaneously resolved, making ablation an overly aggressive and premature intervention.
Catheter ablation procedures US Medical PG Question 2: 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
Catheter ablation procedures 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.
Catheter ablation procedures US Medical PG Question 3: A 16-year-old male presents to the cardiologist after passing out during a basketball practice. An echocardiogram confirmed the diagnosis of hypertrophic cardiomyopathy. The cardiologist advises that a pacemaker must be implanted to prevent any further complications and states the player cannot play basketball anymore. Unfortunately, the coach objects to sidelining the player since a big game against their rivals is next week. The coach asks if the pacemaker can be implanted after the game, which of the following steps should the physician take?
- A. Postpone the procedure so the patient can play
- B. Allow the patient to play and schedule a follow up after the game
- C. Recommend to the legal guardian that the player stop playing and have the procedure performed (Correct Answer)
- D. Perform the procedure immediately so that both the physician and coach's wishes may be fulfilled
- E. Allow the patient to make the decision regarding his health
Catheter ablation procedures Explanation: ***Recommend to the legal guardian that the player stop playing and have the procedure performed***
- The physician's primary ethical duty is **beneficence** and **non-maleficence**, meaning acting in the patient's best interest and preventing harm.
- Playing basketball with **hypertrophic cardiomyopathy** carries a significant risk of sudden cardiac death, making it medically unsafe regardless of the coach's objections.
*Postpone the procedure so the patient can play*
- This option disregards the **immediate and severe risks** associated with hypertrophic cardiomyopathy during strenuous physical activity.
- Postponing the procedure for a game prioritizes a non-medical event over the patient's life-saving treatment, violating the principle of **patient safety**.
*Allow the patient to play and schedule a follow up after the game*
- This is medically irresponsible, as it exposes the patient to a high risk of **sudden cardiac arrest** during the game.
- Delaying urgent intervention for a non-medical reason fails to uphold the physician's obligation to protect the patient from **foreseeable harm**.
*Perform the procedure immediately so that both the physician and coach's wishes may be fulfilled*
- While performing the procedure immediately is medically sound, stating that the coach's wishes can be fulfilled is inaccurate if the player is being sidelined.
- The physician's advice to stop playing basketball stems from medical necessity, which directly conflicts with the coach's desire for the player to participate, thus **not fulfilling both wishes**.
*Allow the patient to make the decision regarding his health*
- While patient autonomy is important, a **16-year-old** is typically considered a minor and cannot make high-risk medical decisions without the consent of a **legal guardian**.
- In situations of significant risk to life, the physician has a responsibility to guide the patient and their guardians towards the safest medical option, rather than simply deferring to the patient's potentially uninformed decision.
Catheter ablation procedures US Medical PG Question 4: A 64-year-old male presents to the emergency room complaining of chest pain. He reports a pressure-like sensation over his sternum that radiates into his jaw. The pain came on suddenly 2 hours ago and has been constant since then. His past medical history is notable for a stable abdominal aortic aneurysm, hypertension, diabetes, and hyperlipidemia. He takes aspirin, enalapril, spironolactone, atorvastatin, canagliflozin, and metformin. His temperature is 99.1°F (37.3°C), blood pressure is 155/85 mmHg, pulse is 115/min, and respirations are 22/min. On exam, he is diaphoretic and in moderate distress. He is admitted for further management and does well after initial stabilization. He is seen two days later by the admitting team. This patient is at increased risk for a complication that is characterized by which of the following?
- A. Cardiac tamponade
- B. Intra-cardiac shunt
- C. Mitral insufficiency (Correct Answer)
- D. Ventricular fibrillation
- E. Friction rub
Catheter ablation procedures Explanation: ***Mitral insufficiency***
- The patient's presentation with **pressure-like chest pain radiating to the jaw**, diaphoresis, and risk factors (hypertension, diabetes, hyperlipidemia) is highly suggestive of an **acute myocardial infarction (MI)**. A common mechanical complication of an MI is **papillary muscle rupture or dysfunction**, leading to acute mitral insufficiency.
- Papillary muscle rupture typically occurs **3-7 days post-MI** and is more common with **inferior wall MI** (affecting the posteromedial papillary muscle supplied by the posterior descending artery).
- Mitral insufficiency significantly increases the risk of **heart failure and cardiogenic shock** due to regurgitant flow into the left atrium during systole, presenting with a new **holosystolic murmur** at the apex.
*Cardiac tamponade*
- This typically occurs due to accumulation of fluid in the **pericardial sac** from a **free wall rupture**, which is a catastrophic mechanical complication of MI.
- Free wall rupture usually presents **acutely with profound cardiogenic shock and hemodynamic collapse** (Beck's triad: hypotension, muffled heart sounds, JVD).
- The patient "does well after initial stabilization," making this less likely as the primary answer.
*Intra-cardiac shunt*
- A **ventricular septal defect (VSD)** from septal rupture is another mechanical complication of MI, typically occurring **3-7 days post-MI**.
- VSD presents with a **new harsh holosystolic murmur** at the left sternal border, step-up in oxygen saturation from RA to RV, and signs of biventricular failure.
- While possible, **mitral regurgitation is more common than VSD** as a post-MI mechanical complication (incidence ratio approximately 10:1).
*Ventricular fibrillation*
- **Ventricular fibrillation** is an **electrical complication** of MI, usually occurring in the **first 24-48 hours** after MI onset and leading to sudden cardiac arrest.
- The patient "does well after initial stabilization" two days later, indicating he survived the acute period when ventricular fibrillation risk is highest.
- The question asks about a complication he is at **increased risk for after initial stabilization**, pointing towards a **subacute mechanical complication** rather than an acute electrical one.
*Friction rub*
- A **pericardial friction rub** is a physical examination finding characteristic of **pericarditis**, which can occur as **early post-MI pericarditis** (24-96 hours) or **Dressler's syndrome** (weeks to months later).
- A friction rub is a **sign** of pericarditis, not a complication itself. The question asks for a complication the patient is at risk for, not a physical examination finding.
- Post-MI pericarditis is generally **benign** and does not carry the same morbidity as mechanical complications like mitral regurgitation.
Catheter ablation procedures US Medical PG Question 5: A 43-year-old man comes to the physician because of increasing shortness of breath for 1 month. He has been using two pillows at night but frequently wakes up feeling as if he is choking. Five months ago, he underwent surgery for creation of an arteriovenous fistula in his left upper arm. He has hypertension and chronic kidney disease due to reflux nephropathy. He receives hemodialysis three times a week. His current medications are enalapril, vitamin D3, erythropoietin, sevelamer, and atorvastatin. His temperature is 37.1°C (98.8°F), respirations are 22/min, pulse is 103/min and bounding, and blood pressure is 106/58 mm Hg. Examination of the lower extremities shows bilateral pitting pedal edema. There is jugular venous distention. A prominent thrill is heard over the brachiocephalic arteriovenous fistula. There are crackles heard at both lung bases. Cardiac examination shows an S3 gallop. The abdomen is soft and nontender. Which of the following is the most likely cause of this patient's symptoms?
- A. AV fistula aneurysm
- B. Pulmonary embolism
- C. Constrictive pericarditis
- D. Dialysis disequilibrium syndrome
- E. High-output heart failure (Correct Answer)
Catheter ablation procedures Explanation: ***High-output heart failure***
- The patient's symptoms of **dyspnea, orthopnea, pitting edema, jugular venous distention, crackles**, and **S3 gallop** strongly indicate **heart failure**. The **bounding pulse** and **wide pulse pressure** (systolic 106, diastolic 58) in the presence of an **arteriovenous fistula** suggest a **high-output state**.
- An **arteriovenous fistula** used for hemodialysis can significantly increase **cardiac preload** and reduce **afterload**, leading to a persistent increase in **cardiac output**. Over time, this chronic increase in demand can overwhelm the heart, resulting in **high-output heart failure**.
*AV fistula aneurysm*
- An **AV fistula aneurysm** is a localized dilatation of the fistula and would typically present as a painful or compressible mass.
- While it's a complication of AV fistulas, it does not directly explain the systemic signs of **heart failure** observed in this patient.
*Pulmonary embolism*
- **Pulmonary embolism** typically presents with sudden onset **dyspnea, pleuritic chest pain**, and sometimes **tachycardia** and **hypoxia**.
- This patient's symptoms are of gradual onset, accompanied by clear signs of **fluid overload** and **cardiac dysfunction** like an S3 gallop, which are not typical for a PE.
*Constrictive pericarditis*
- **Constrictive pericarditis** causes symptoms of **right-sided heart failure** due to impaired diastolic filling, often with a **pericardial knock** and **Kussmaul's sign**.
- While it can manifest with pedal edema and JVD, the **S3 gallop** and especially the **bounding pulse** and **wide pulse pressure** are inconsistent with constrictive pericarditis, which would typically cause a low-output state.
*Dialysis disequilibrium syndrome*
- **Dialysis disequilibrium syndrome** occurs shortly after hemodialysis, usually during or immediately after the first few sessions. It is characterized by neurological symptoms such as **headache, nausea, vomiting, confusion**, and **seizures**.
- The patient's symptoms have been evolving over a month and describe a state of **fluid overload** and **cardiac dysfunction**, not acute neurological symptoms related to dialysis.
Catheter ablation procedures US Medical PG Question 6: A 47-year-old woman comes to the emergency department after coughing up 2 cups of bright red blood. A CT angiogram of the chest shows active extravasation from the right bronchial artery. A coil embolization is planned to stop the bleeding. During this procedure, a catheter is first inserted into the right femoral artery. Which of the following represents the correct subsequent order of the catheter route?
- A. Thoracic aorta, right superior epigastric artery, right bronchial artery
- B. Thoracic aorta, right bronchial artery (Correct Answer)
- C. Thoracic aorta, left ventricle, left atrium, pulmonary artery, right bronchial artery
- D. Thoracic aorta, brachiocephalic trunk, right subclavian artery, right internal thoracic artery, right bronchial artery
- E. Thoracic aorta, right subclavian artery, right internal thoracic artery, right bronchial artery
Catheter ablation procedures Explanation: ***Thoracic aorta, right bronchial artery***
- The **femoral artery** leads directly into the **aorta**. From the aorta, the catheter can be navigated to the **thoracic aorta**, where the **bronchial arteries** typically originate.
- The **bronchial arteries** usually arise directly from the **descending thoracic aorta** (most commonly T5-T6 vertebral level) to supply the lung parenchyma and airways.
*Thoracic aorta, right superior epigastric artery, right bronchial artery*
- The **superior epigastric artery** is a terminal branch of the **internal thoracic artery**, supplying the anterior abdominal wall, and is not a direct path to the bronchial arteries.
- Navigating from the superior epigastric artery to the main bronchial artery without passing through intermediary large vessels would be anatomically incorrect and impractical.
*Thoracic aorta, left ventricle, left atrium, pulmonary artery, right bronchial artery*
- This path describes the venous and then pulmonary circulation (right heart, lungs), which is incorrect for reaching the **arterial system** of the bronchial arteries.
- A catheter inserted via the **femoral artery** remains within the arterial system and would not cross into the pulmonary circulation or the left heart chambers in this manner.
*Thoracic aorta, brachiocephalic trunk, right subclavian artery, right internal thoracic artery, right bronchial artery*
- This pathway involves ascending from the **thoracic aorta** to the **brachiocephalic trunk** and subsequently into the **right subclavian** and **internal thoracic arteries**, which is a route primarily to the upper limb and chest wall.
- While the internal thoracic artery can sometimes have small anastomoses, it is not the primary or direct route for embolizing a bronchial artery, which typically originates directly from the descending thoracic aorta.
*Thoracic aorta, right subclavian artery, right internal thoracic artery, right bronchial artery*
- Similar to the previous incorrect option, this route involves navigating through the **subclavian** and **internal thoracic arteries**, which is an indirect and unnecessarily complex path to the bronchial arteries.
- The **bronchial arteries** are direct branches of the **thoracic aorta**, making this a much more convoluted and less likely route for therapeutic embolization.
Catheter ablation procedures US Medical PG Question 7: A 58-year-old man is diagnosed with right lower lobe pneumonia and has been admitted to a tertiary care hospital. His laboratory investigations suggest that he acquired an infection from the hospital where he underwent an elective abdominal surgery 3 weeks ago. His past medical records reveal a history of deep vein thrombosis and pulmonary embolism one year prior. After a steady clinical improvement over 5 days of inpatient treatment, he develops a cough, breathlessness, and hemoptysis on the 6th day. His temperature is 38.6°C (101.5°F), the pulse is 112/min, the blood pressure is 130/84 mm Hg, and the respiratory rate is 28/min. A general examination shows the presence of edema over the right leg and tenderness over the right calf region. Auscultation of the chest reveals localized crackles over the left mammary region and right infrascapular region. However, his heart sounds are normal, except for the presence of tachycardia, and there are no murmurs. Which of the following is the investigation of choice as the immediate next step in this patient’s management?
- A. Ventilation-perfusion scanning
- B. Echocardiography
- C. Contrast-enhanced computed tomography (CECT) of chest (Correct Answer)
- D. Serum brain natriuretic peptide
- E. Plasma D-dimer
Catheter ablation procedures Explanation: ***Contrast-enhanced computed tomography (CECT) of chest***
- This patient presents with an acute onset of **cough, breathlessness, and hemoptysis** along with signs of **deep vein thrombosis (DVT)**, including leg edema and calf tenderness. This clinical picture, especially with a history of DVT and pulmonary embolism, is highly suggestive of a **pulmonary embolism (PE)**.
- **CT pulmonary angiography (CTPA)**, performed as a contrast-enhanced CT of the chest, is the **gold standard** for diagnosing PE, as it directly visualizes thrombi within the pulmonary arteries and provides detailed anatomical information.
- Given the **high pre-test probability** (prior DVT/PE, clinical signs of DVT, recent surgery, hemoptysis, tachycardia), immediate imaging with CTPA is indicated without need for D-dimer testing.
*Ventilation-perfusion scanning*
- **Ventilation-perfusion (V/Q) scanning** is an alternative for diagnosing PE, but it is less sensitive and specific than CTPA, especially in the presence of **pre-existing lung disease** (like the pneumonia this patient has), which can lead to indeterminate results.
- It is usually reserved for patients with **renal insufficiency** or **contrast allergy** who cannot undergo CTPA.
*Echocardiography*
- **Echocardiography** can show signs of **right heart strain** in massive PE, but it is not diagnostic for PE itself, as it cannot directly visualize the emboli in the pulmonary arteries.
- It is more useful in assessing **cardiac function** and ruling out other cardiac causes of breathlessness, or for risk stratification in confirmed PE.
*Serum brain natriuretic peptide*
- **Serum brain natriuretic peptide (BNP)** levels can be elevated in patients with **right heart strain** due to PE, but it is a **non-specific marker** and cannot confirm the diagnosis of PE.
- Elevated BNP can also indicate other cardiac conditions, such as **heart failure**.
*Plasma D-dimer*
- **Plasma D-dimer** is a useful test to **exclude PE** in patients with a **low or intermediate pre-test probability**, but a **positive D-dimer** is non-specific and can be elevated in many conditions, including infection, surgery, and inflammation.
- Given the patient's **high clinical probability** for PE (prior DVT/PE, current DVT signs, recent surgery, hemoptysis) and active pneumonia, D-dimer testing is **not indicated** as it would not change management—imaging with CTPA is already warranted regardless of D-dimer result.
Catheter ablation procedures US Medical PG Question 8: 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
Catheter ablation procedures 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.
Catheter ablation procedures US Medical PG Question 9: 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
Catheter ablation procedures 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.
Catheter ablation procedures US Medical PG Question 10: 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
Catheter ablation procedures 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.
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