A 58-year-old female presents to her primary care physician with complaints of chest pain and palpitations. A thorough past medical history reveals a diagnosis of rheumatic fever during childhood. Echocardiography is conducted and shows enlargement of the left atrium and narrowing of the mitral valve opening. Which of the following should the physician expect to hear on cardiac auscultation?

Continuous, machine-like murmur

Holosystolic murmur that radiates to the axilla

High-pitched, blowing decrescendo murmur in early diastole

Cardiac muscle serves many necessary functions, leading to a specific structure that serves these functions. The structure highlighted is an important histology component of cardiac muscle. What would be the outcome if this structure diffusely failed to function?

Failure of propagation of the action potential from the conduction system

Failure of potassium channels to appropriately open to repolarize the cell

Ineffective excitation-contraction coupling due to insufficient calcium ions

Inappropriate formation of cardiac valve leaflets

A 38-year-old female presents to the emergency room with fevers, fatigue, and anorexia for over a month. Past medical history includes mild mitral valve prolapse. She underwent an uncomplicated tooth extraction approximately 6 weeks ago. Her vital signs include a temperature of 100.8 F, pulse of 83, blood pressure of 110/77, and SpO2 of 97% on room air. On exam, you note a grade III/VI holosystolic murmur at the apex radiating to the axilla as well as several red, painful nodules on her fingers. Which of the following is the next best course of action?

Obtain blood cultures x3 sites over 1 hour and start empiric antibiotics

Blood cultures are not needed. Start empiric antibiotics

Start anticoagulation with heparin

Consult cardiothoracic surgery for mitral valve replacement

Obtain blood cultures x3 sites over 24 hours and start antibiotics after culture results are available

A 32-year-old woman is supposed to undergo tooth extraction surgery. Physical examination is unremarkable, and she has a blood pressure of 126/84 mm Hg and regular pulse of 72/min. She takes no medications. Which of the following cardiac conditions would warrant antibiotic prophylaxis to prevent infective endocarditis in this patient?

Past history of infective endocarditis

Hypertrophic obstructive cardiomyopathy (HOCM)

Ventricular septal defect (VSD)

Implantable cardioverter defibrillator (ICD)

A 61-year-old white man presents to the emergency department because of progressive fatigue and shortness of breath on exertion and while lying down. He has had type 2 diabetes mellitus for 25 years and hypertension for 15 years. He is taking metformin and captopril for his diabetes and hypertension. He has smoked 10 cigarettes per day for the past 12 years and drinks alcohol occasionally. His temperature is 36.7°C (98.0°F) and blood pressure is 130/60 mm Hg. On physical examination, his arterial pulse shows a rapid rise and a quick collapse. An early diastolic murmur is audible over the left upper sternal border. Echocardiography shows severe chronic aortic regurgitation with a left ventricular ejection fraction of 55%–60% and mild left ventricular hypertrophy. Which of the following is an indication for aortic valve replacement in this patient?

Presence of symptoms of left ventricular dysfunction

Long history of diabetes mellitus

Long history of systemic hypertension

A 67-year-old man presents to the emergency department with abdominal pain that started 1 hour ago. The patient has a past medical history of diabetes and hypertension as well as a 40 pack-year smoking history. His blood pressure is 107/58 mmHg, pulse is 130/min, respirations are 23/min, and oxygen saturation is 98% on room air. An abdominal ultrasound demonstrates focal dilation of the aorta with peri-aortic fluid. Which of the following is the best next step in management?

Serial annual abdominal ultrasounds

Counsel the patient in smoking cessation

Urgent surgery within the next day

A 70-year-old man with severe ischemic cardiomyopathy (EF 25%) has recurrent ventricular tachycardia despite optimal medical therapy and ICD placement. Cardiac MRI shows a large anteroseptal scar with viable myocardium in the lateral and inferior walls. He has three-vessel coronary disease. His daughter is advocating for heart transplantation, but he has multiple comorbidities including obesity (BMI 37) and active tobacco use. Evaluate the management priority and rationale.

CABG with surgical ventricular reconstruction and continued medical optimization

Left ventricular assist device as destination therapy

Catheter ablation of VT with continued ICD monitoring

Cardiac resynchronization therapy upgrade and medication adjustment

List for heart transplantation immediately given severe cardiomyopathy

Valve replacement and repair procedures for USMLE Step 2 CK: High-Yield Surgery Lessons

🚪 The Failing Gates

Intervention for severe valvular disease is indicated for:

Symptom onset (dyspnea, angina, syncope).
LV dysfunction (e.g., EF < 60% in MR, < 50% in AS/AR).
Significant LV dilation.

⭐ In aortic stenosis, symptoms (Angina, Syncope, Heart Failure - 📌 "ASH") are a critical indication for replacement, as symptom onset carries a poor prognosis.

🚪 Anatomy - Heart's Hinged Doors

Superior view of heart valves and coronary arteries

Four Valves: Control unidirectional blood flow. 📌 Mnemonic: Try Pulling My Aorta.
Atrioventricular (AV) Valves: Supported by chordae tendineae & papillary muscles.
- Tricuspid: 3 leaflets (RA → RV).
- Mitral (Bicuspid): 2 leaflets (LA → LV).
Semilunar (SL) Valves:
- Aortic: 3 cusps (LV → Aorta).
- Pulmonary: 3 cusps (RV → Pulmonary Artery).
Annulus: Fibrous ring forming the valve's "door frame"; key surgical anchor point.

⭐ The mitral valve apparatus is the most complex, making it a frequent target for intricate repair procedures over simple replacement to preserve LV function.

🔧 Management - A Mechanic's Choice

Valve Repair: Preferred over replacement when feasible, especially for degenerative mitral regurgitation. Preserves native valve geometry, avoids lifelong anticoagulation, and has lower operative mortality.

Bioprosthetic vs. Mechanical Mitral Valve Replacement Study

Feature	Mechanical Valve	Bioprosthetic (Tissue) Valve
Durability	Very high (>20 yrs); risk of pannus	Lower (10-15 yrs); risk of structural failure
Thrombogenicity	High; audible "click"	Low; silent operation
Anticoagulation	Lifelong Warfarin	3-6 months post-op, then often ASA
Ideal Patient	Younger (<60-65 yrs), compliant	Older (>65 yrs), non-compliant, pregnancy planned

⚠️ Endocarditis Prophylaxis: Required for all prosthetic valves and valve repairs using prosthetic material before certain dental/respiratory procedures.

⚠️ Complications - Post-Op Perils

Early (<30 days):
- Arrhythmias: New-onset AFib (most common); heart block (risk with AVR near AV node).
- Bleeding/Tamponade: Beck's triad (hypotension, JVD, muffled heart sounds).
- Thromboembolism: Ischemic stroke risk.
- Post-pericardiotomy Syndrome: Autoimmune; fever, pleuritic pain, effusion 1-6 wks post-op.
Late (>30 days):
- Prosthetic Valve Endocarditis (PVE): Early (<1yr) S. aureus; Late (>1yr) Viridans strep.
- Valve Dysfunction: Thrombosis, pannus, paravalvular leak (PVL), structural deterioration (bioprosthetic).
- Hemolysis: Mechanical valves > bioprosthetic; see schistocytes, ↑LDH.

⭐ Pearl: New-onset heart block after aortic valve replacement suggests potential injury to the AV node or a perivalvular abscess. Requires immediate investigation.

⚡ Biggest Takeaways

Mechanical valves are durable but require lifelong warfarin (INR 2.5-3.5 for mitral, 2.0-3.0 for aortic).

Bioprosthetic valves are less durable (10-15 yrs) but avoid long-term anticoagulation; preferred in older patients.

Indications: Symptomatic severe disease or asymptomatic with LV dysfunction (EF < 50%).

Prosthetic valves require endocarditis prophylaxis for high-risk procedures (e.g., dental).

TAVR is a less invasive option for high-risk aortic stenosis patients.

Mitral valve repair is favored over replacement for regurgitation to preserve LV function.

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