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ABTS Thoracic Surgery study materials
ABTS Thoracic Surgery study resources

ABTS Thoracic Surgery practice questions

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Question 1Adult Cardiac Surgery

A 63-year-old man with three-vessel coronary disease is scheduled for coronary artery bypass grafting. Which conduit provides the best long-term patency when used to bypass the left anterior descending artery?

  1. Great saphenous vein
  2. Left internal thoracic artery Correct answer.
  3. Right gastroepiploic artery
  4. Radial artery

Explanation

The left internal thoracic artery is the conduit of choice for the left anterior descending artery because it is an arterial graft with long-term patency of roughly 90 percent at 10 years, whereas vein grafts fail progressively from intimal hyperplasia and atherosclerosis. Its use for the LAD is the single technical factor most consistently linked to improved late survival after coronary bypass.

Question 2Adult Cardiac Surgery

A 72-year-old woman has severe calcific aortic stenosis (valve area 0.8 cm2, mean gradient 45 mmHg) and reports exertional dyspnea and two episodes of syncope. What is the most appropriate management?

  1. Long-term statin and beta-blocker therapy
  2. Balloon aortic valvuloplasty alone
  3. Continued observation with annual echocardiography
  4. Aortic valve replacement Correct answer.

Explanation

Symptomatic severe aortic stenosis is a class I indication for valve replacement, delivered surgically or transcatheter according to risk and anatomy. Once angina, syncope, or heart failure appears, mortality rises steeply within a few years, and no medical therapy alters the natural history of the lesion.

Question 3Adult Cardiac Surgery

Before cannulation and institution of cardiopulmonary bypass, heparin is given and monitored by the activated clotting time. What target value is required in standard adult cardiac surgery?

  1. 480 seconds Correct answer.
  2. 900 seconds
  3. 150 seconds
  4. 250 seconds

Explanation

Heparin effect during cardiopulmonary bypass is titrated to the activated clotting time, and most adult protocols require a value of at least 400 to 480 seconds before bypass is begun. Values below this range risk thrombus formation within the circuit and oxygenator, while unnecessarily high targets increase bleeding and transfusion requirements. Deep hypothermic circulatory arrest protocols sometimes use higher targets.

Question 4Adult Cardiac Surgery

A 58-year-old hypertensive man presents with sudden tearing chest pain. CT angiography shows an acute type A aortic dissection with the intimal flap in the ascending aorta and a small pericardial effusion. What is the definitive management?

  1. Thoracic endovascular repair of the descending aorta
  2. Systemic thrombolysis with a tissue plasminogen activator
  3. Emergent open aortic repair Correct answer.
  4. Intravenous labetalol with serial CT imaging

Explanation

Acute type A dissection is a surgical emergency because the ascending aorta may rupture into the pericardium, causing tamponade, or may compromise coronary, cerebral, or visceral perfusion; mortality rises with every hour of delay. Rate and blood pressure control are started immediately but serve only as a bridge while the patient is transported to the operating room.

Question 5Adult Cardiac Surgery

A patient is scheduled for elective coronary artery bypass grafting. Which prophylactic measure has the strongest evidence for reducing the incidence of postoperative atrial fibrillation?

  1. Routine prophylactic atrial pacing
  2. Prophylactic oral anticoagulation started on day one
  3. Prophylactic amiodarone in every patient
  4. Perioperative beta-blocker therapy Correct answer.

Explanation

Perioperative beta-blockade is the best established prophylaxis for atrial fibrillation after cardiac surgery and reduces its incidence by roughly half. Amiodarone is reserved for patients at high risk or for treatment of established arrhythmia, and neither pacing nor early therapeutic anticoagulation prevents the arrhythmia.

Question 6Adult Cardiac Surgery

A 62-year-old man has severe degenerative mitral regurgitation caused by isolated posterior leaflet prolapse. Ejection fraction is 62 percent, the left ventricle is not dilated, and he has new exertional dyspnea. What is the preferred operation?

  1. Continued medical management with diuretics
  2. Percutaneous balloon mitral commissurotomy
  3. Mitral valve repair Correct answer.
  4. Mechanical mitral valve replacement

Explanation

In degenerative mitral regurgitation from isolated posterior leaflet prolapse with preserved ventricular function, repair carries lower operative mortality and better long-term survival than replacement and avoids lifelong anticoagulation. Surgery is indicated once symptoms appear or when ventricular dysfunction or dilation develops.

Question 7Adult Cardiac Surgery

Six hours after an uncomplicated coronary bypass operation, a patient becomes hypotensive and tachycardic, with distended neck veins, rising central venous pressure, and oliguria. Chest tube output has abruptly fallen to near zero. What is the most appropriate next step?

  1. Rapid infusion of crystalloid and diuretic therapy
  2. Immediate mediastinal reexploration Correct answer.
  3. Contrast-enhanced CT of the chest
  4. Subxiphoid pericardiocentesis

Explanation

The presentation is classic for tamponade from clotted mediastinal blood, in which drain output falls as clot occludes the chest tubes while filling pressures rise. Because the blood is clotted and loculated and the pericardium is adherent after surgery, percutaneous drainage is unreliable, and reexploration is the definitive treatment. Bedside echocardiography may support the diagnosis but should not delay surgery in an unstable patient.

Question 8Adult Cardiac Surgery

A 48-year-old man with aortic valve endocarditis has persistent fever after 10 days of appropriate intravenous antibiotics. He has developed a new first-degree atrioventricular block, and transesophageal echocardiography shows a perivalvular abscess. What is the most appropriate management?

  1. Percutaneous drainage of the abscess cavity
  2. Continued antibiotics alone for a full six weeks
  3. Addition of a second antibiotic with reassessment in two weeks
  4. Urgent valve replacement with root debridement Correct answer.

Explanation

Persistent infection despite appropriate antibiotics, new conduction abnormality, and imaging evidence of a perivalvular abscess indicate uncontrolled infection with local extension, which is a surgical indication. Antibiotics cannot sterilize an abscess cavity, so debridement of infected tissue with valve replacement is required, and delay worsens the risk of root destruction and death.

Question 9Adult Cardiac Surgery

A 68-year-old man with a left ventricular ejection fraction of 30 percent has an aortic valve area of 0.9 cm2 and a mean gradient of only 22 mmHg at rest. Dobutamine stress echocardiography increases the gradient and demonstrates contractile reserve. What is the most appropriate treatment?

  1. Balloon aortic valvuloplasty as definitive treatment
  2. Continued medical therapy with diuretics
  3. Initiation of an ACE inhibitor with repeat echocardiography in six months
  4. Aortic valve replacement Correct answer.

Explanation

Low-flow, low-gradient severe aortic stenosis with contractile reserve on dobutamine testing identifies true severe stenosis, and valve replacement improves survival compared with continued medical management. Because the ventricle is severely impaired, the gradient underestimates severity at rest, and provocative testing is what establishes the indication.

Question 10Adult Cardiac Surgery

Twelve hours after implantation of a continuous-flow left ventricular assist device, a patient has a low cardiac index, elevated central venous pressure, clear lungs on imaging, and a underfilled left ventricle on echocardiography. What is the most appropriate initial management?

  1. Inhaled nitric oxide with inotropic support Correct answer.
  2. Escalating intravenous norepinephrine to raise systemic pressure
  3. Increasing pump speed and giving a fluid bolus
  4. Aggressive diuresis to reduce preload

Explanation

These findings indicate right ventricular failure, which limits filling of the left ventricle and produces a low output despite clear lungs. Selective pulmonary vasodilation with inhaled nitric oxide lowers right ventricular afterload, and inotropic support augments right ventricular contractility. Fluid loading and higher pump speeds worsen right ventricular distension and septal shift.

Question 11Adult Cardiac Surgery

During normothermic cardiopulmonary bypass in an adult, which indexed pump flow is typically targeted to maintain adequate systemic perfusion?

  1. 1.0 L/min/m2
  2. 2.4 L/min/m2 Correct answer.
  3. 1.6 L/min/m2
  4. 3.8 L/min/m2

Explanation

Adult cardiopulmonary bypass flow is usually indexed to body surface area at about 2.2 to 2.4 L/min/m2 during normothermia, with adjustment guided by oxygen delivery, mixed venous saturation, and lactate. Lower flows may be used with hypothermia, but 2.4 L/min/m2 is the standard normothermic target. Flows near 1.0 or 1.6 L/min/m2 are generally inadequate for normothermic perfusion, while 3.8 L/min/m2 exceeds typical requirements and increases circuit trauma.

Question 12Adult Cardiac Surgery

A 45-year-old woman has a mechanical bileaflet valve in the mitral position and no additional thrombotic risk factors. Which target INR range is recommended for long-term anticoagulation?

  1. 1.5 to 2.0
  2. 3.5 to 4.5
  3. 2.0 to 3.0
  4. 2.5 to 3.5 Correct answer.

Explanation

Mechanical mitral valves require a higher intensity of anticoagulation than aortic valves because of the lower flow velocity and greater thrombogenic risk in the mitral position. Guidelines recommend a target INR of 2.5 to 3.5 for a mechanical mitral valve without additional risk factors. An INR of 2.0 to 3.0 is typical for a mechanical aortic valve, while 1.5 to 2.0 is inadequate for a mechanical mitral prosthesis.

Question 13Adult Cardiac Surgery

On the second day after coronary artery bypass grafting, a patient develops atrial fibrillation at 150 beats/min with a systolic blood pressure of 78 mmHg and cool extremities. Which intervention is most appropriate initially?

  1. Start an intravenous amiodarone infusion
  2. Initiate oral metoprolol
  3. Perform synchronized electrical cardioversion Correct answer.
  4. Administer intravenous digoxin

Explanation

Postoperative atrial fibrillation with hemodynamic instability, such as hypotension and poor perfusion, requires urgent synchronized electrical cardioversion. Rate-control or antiarrhythmic drugs are appropriate for stable patients but act too slowly when perfusion is compromised. Electrical cardioversion restores sinus rhythm and improves cardiac output promptly.

Question 14Adult Cardiac Surgery

Ten days after median sternotomy, a patient has fever, sternal instability, and purulent drainage from the wound. Which management strategy is most appropriate?

  1. Superficial wound debridement alone
  2. Oral antibiotics and observation
  3. Surgical debridement with flap coverage and intravenous antibiotics Correct answer.
  4. Negative-pressure wound therapy alone without surgical debridement and with oral antibiotics

Explanation

Poststernotomy mediastinitis requires aggressive surgical debridement of necrotic tissue and infected bone, followed by muscle or omental flap coverage when needed, together with culture-directed intravenous antibiotics. Superficial drainage or antibiotics alone do not eradicate deep sternal infection. Negative-pressure therapy can be an adjunct but does not replace adequate debridement.

Question 15Adult Cardiac Surgery

Immediately after protamine administration following cardiopulmonary bypass, a patient develops profound hypotension, bronchospasm, and elevated pulmonary artery pressure. Which agent is most appropriate for initial treatment?

  1. Sodium bicarbonate
  2. Epinephrine Correct answer.
  3. Hydrocortisone
  4. Diphenhydramine

Explanation

This presentation suggests an anaphylactic or anaphylactoid protamine reaction, and intramuscular or intravenous epinephrine is the first-line treatment for severe hypotension and bronchospasm. Epinephrine supports blood pressure, reduces mediator release, and relieves bronchoconstriction. Antihistamines and steroids are adjuncts but do not reverse acute cardiovascular collapse.

Question 16Adult Cardiac Surgery

A patient cannot be weaned from cardiopulmonary bypass because of low cardiac output despite high-dose inotropes. Which finding best supports placement of an intra-aortic balloon pump?

  1. Severe bilateral aortoiliac occlusive disease with rest pain
  2. Refractory low cardiac output despite maximal inotropic support Correct answer.
  3. Acute type B aortic dissection with visceral malperfusion
  4. Moderate aortic regurgitation with a normal left ventricle

Explanation

An intra-aortic balloon pump is indicated for refractory low cardiac output after cardiac surgery because counterpulsation reduces left ventricular afterload and improves coronary and systemic perfusion. Severe aortoiliac occlusive disease and aortic dissection are contraindications because of the risk of vascular injury or malperfusion. Significant aortic regurgitation is also a relative contraindication because balloon inflation can worsen regurgitation.

Question 17Adult Cardiac Surgery

A 40-year-old man has a 5.2-cm aortic root aneurysm, a tricuspid aortic valve with no more than mild regurgitation, and normal leaflet motion. Which operation is most appropriate?

  1. Aortic valve replacement with a bioprosthesis
  2. Composite graft replacement with a mechanical valve
  3. Valve-sparing aortic root replacement Correct answer.
  4. Transcatheter aortic valve replacement

Explanation

In a young patient with a dilated aortic root and a repairable tricuspid valve with normal leaflet motion, valve-sparing root replacement avoids prosthetic valve anticoagulation and preserves native valve function. Composite graft replacement commits the patient to lifelong anticoagulation if a mechanical valve is used. Transcatheter and isolated bioprosthetic valve replacement do not address the root aneurysm.

Question 18Adult Cardiac Surgery

A patient undergoing mitral valve repair has moderate functional tricuspid regurgitation and a tricuspid annulus diameter of 42 mm on echocardiography. Which concomitant procedure is most appropriate?

  1. Tricuspid valve replacement
  2. No intervention
  3. Tricuspid annuloplasty Correct answer.
  4. Pulmonary valve replacement

Explanation

Moderate functional tricuspid regurgitation with annular dilation, typically 40 mm or greater, is an indication for concomitant tricuspid annuloplasty at the time of left-sided valve surgery. Annuloplasty stabilizes the annulus and prevents progression of regurgitation. Valve replacement is reserved for severe leaflet pathology that cannot be repaired, and pulmonary valve replacement is unrelated.

Question 19Adult Cardiac Surgery

A patient with recent heparin exposure has a platelet count that falls by 55 percent and develops a new arterial thrombosis. Heparin-induced thrombocytopenia is suspected. Which anticoagulant strategy is most appropriate if urgent cardiac surgery is required?

  1. Use warfarin alone
  2. Use bivalirudin as the anticoagulant Correct answer.
  3. Switch to low-molecular-weight heparin
  4. Continue unfractionated heparin at a higher dose

Explanation

Heparin-induced thrombocytopenia is an immune-mediated reaction in which heparin exposure can cause thrombosis, so all heparin products must be stopped. For urgent cardiac surgery, a direct thrombin inhibitor such as bivalirudin is used because it provides anticoagulation without triggering the heparin-platelet antibody response. Low-molecular-weight heparin and warfarin are inappropriate in this setting.

Question 20Adult Cardiac Surgery

During repair of a transverse aortic arch aneurysm, which strategy best reduces cerebral ischemic injury during hypothermic circulatory arrest?

  1. Retrograde cerebral perfusion as the sole strategy at 35°C
  2. Circulatory arrest without any cerebral protection for 60 minutes
  3. Selective antegrade cerebral perfusion with systemic hypothermia Correct answer.
  4. Systemic normothermia without cerebral perfusion

Explanation

Selective antegrade cerebral perfusion during systemic hypothermia maintains oxygen delivery to the brain and permits longer, safer periods of circulatory arrest for arch reconstruction. Normothermia without cerebral perfusion and prolonged unprotected arrest cause rapid ischemic injury. Retrograde cerebral perfusion is less effective as a sole strategy, especially at mild hypothermia.

Question 21Adult Cardiac Surgery

During cardiopulmonary bypass with a membrane oxygenator, which adjustment most directly reduces the arterial partial pressure of carbon dioxide?

  1. Increasing the fraction of oxygen in the sweep gas
  2. Adding carbon dioxide to the sweep gas mixture
  3. Increasing sweep gas flow through the oxygenator Correct answer.
  4. Increasing the pump flow rate through the circuit

Explanation

Sweep gas flow governs carbon dioxide elimination across the membrane; higher flow washes out more CO2 and lowers arterial PaCO2. Changing the oxygen fraction alters oxygenation rather than ventilation. Pump flow affects tissue perfusion and venous return but does not directly set gas exchange.

Question 22Adult Cardiac Surgery

During antegrade delivery of cold blood cardioplegia into the aortic root, which mechanism primarily produces and maintains diastolic arrest?

  1. Profound hypothermia alone abolishing electrical activity
  2. Potassium-induced membrane depolarization Correct answer.
  3. Sodium channel blockade slowing depolarization
  4. Calcium channel blockade reducing contractility

Explanation

The high potassium concentration in cardioplegic solution depolarizes the myocyte membrane, inactivating fast sodium channels and preventing further action potentials. Arrest then persists as long as the depolarizing solution is present. Hypothermia and other additives slow metabolism but are not the primary arresting mechanism.

Question 23Adult Cardiac Surgery

A 70-year-old man has a bioprosthetic aortic valve and no other indication for long-term anticoagulation. Which antithrombotic strategy is recommended?

  1. Warfarin with a target INR of 2.5 to 3.5
  2. Aspirin 75 to 100 mg daily Correct answer.
  3. No antithrombotic therapy at all
  4. Dual antiplatelet therapy for 12 months

Explanation

Guidelines recommend low-dose aspirin (75 to 100 mg daily) for patients with a bioprosthetic aortic valve who have no separate indication for anticoagulation. Warfarin is reserved for mechanical valves or other conditions such as atrial fibrillation. Dual antiplatelet therapy adds bleeding risk without proven benefit in this setting.

Question 24Adult Cardiac Surgery

A 45-year-old woman has symptomatic severe rheumatic mitral stenosis with a pliable valve, no commissural calcification, and no left atrial thrombus. Which intervention is most appropriate?

  1. Continued medical therapy until symptoms become refractory
  2. Percutaneous balloon mitral valvuloplasty Correct answer.
  3. Mitral valve replacement with a mechanical prosthesis
  4. Open surgical commissurotomy through a median sternotomy

Explanation

Percutaneous balloon mitral valvuloplasty is the preferred intervention for symptomatic severe rheumatic mitral stenosis when valve morphology is favorable and no left atrial thrombus is present. Surgery is reserved for unfavorable anatomy, failed balloon valvuloplasty, or concomitant disease requiring operation. Delay increases the risk of pulmonary hypertension and atrial fibrillation.

Question 25Adult Cardiac Surgery

A 60-year-old man with infective endocarditis develops acute severe aortic regurgitation and pulmonary edema. Which management principle is correct?

  1. Intra-aortic balloon counterpulsation should be used to stabilize him
  2. Urgent aortic valve surgery is indicated Correct answer.
  3. Antibiotics alone should be continued until fever resolves
  4. Vasoconstrictors are preferred to maintain coronary perfusion

Explanation

Acute severe aortic regurgitation causes sudden left ventricular volume overload with a non-compliant ventricle, high filling pressures, and low forward output, so urgent valve surgery is indicated. Antibiotics will not correct the mechanical lesion. Intra-aortic balloon counterpulsation is contraindicated because diastolic augmentation worsens regurgitation.

Question 26Adult Cardiac Surgery

Which hemodynamic finding best distinguishes constrictive pericarditis from restrictive cardiomyopathy?

  1. Discordant right and left ventricular pressure changes with respiration Correct answer.
  2. A pulsus paradoxus greater than 10 mmHg
  3. Reduced left ventricular ejection fraction
  4. Elevated right atrial pressure

Explanation

In constrictive pericarditis, the rigid pericardium imposes ventricular interdependence, so inspiratory filling of the right ventricle reduces left ventricular filling, producing discordant pressure changes. Restrictive cardiomyopathy shows concordant pressure changes. Elevated filling pressures and pulsus paradoxus can occur in both conditions.

Question 27Adult Cardiac Surgery

A 50-year-old man 3 months after heart transplantation presents with fatigue, low-grade fever, and a rising troponin level. Which diagnosis should be suspected first?

  1. Acute cellular rejection Correct answer.
  2. Tacrolimus toxicity
  3. Acute bacterial mediastinitis
  4. Chronic allograft vasculopathy

Explanation

Fever, fatigue, and elevated troponin in the first year after transplantation suggest acute allograft rejection, which is confirmed by endomyocardial biopsy. Chronic allograft vasculopathy usually presents later with ischemic symptoms or graft dysfunction. Infection and drug toxicity are alternative diagnoses but are less likely to present with isolated troponin elevation.

Question 28Adult Cardiac Surgery

A 55-year-old woman has a 4-cm left atrial mass attached to the interatrial septum, consistent with a myxoma. Which surgical principle applies?

  1. Proceed directly to orthotopic heart transplantation
  2. Remove only the intracavitary portion of the tumor
  3. Obtain a biopsy of the mass before excision
  4. Excise the mass together with its septal attachment Correct answer.

Explanation

Myxomas are excised with a margin of full-thickness atrial septum to reduce the risk of recurrence, and the septum is then reconstructed. The mass is handled gently to avoid fragmentation and systemic embolization. Biopsy before removal is unnecessary and risks dislodging tumor.

Question 29Adult Cardiac Surgery

Retrograde cardioplegia delivered through the coronary sinus provides the least reliable protection to which region of the heart?

  1. The interventricular septum
  2. The left anterior descending coronary territory
  3. The right ventricle Correct answer.
  4. The circumflex coronary territory

Explanation

Retrograde flow preferentially perfuses the left ventricle through the coronary venous system and may not reach the right ventricular free wall adequately, especially when the balloon-tipped cannula does not fully occlude the coronary sinus. Right ventricular hypertrophy or coronary venous anomalies further reduce delivery. Antegrade or combined delivery improves right-sided protection.

Question 30Adult Cardiac Surgery

A 55-year-old woman with a mechanical mitral valve and a subtherapeutic INR presents in cardiogenic shock with a large thrombus causing valve obstruction. Which management is most appropriate?

  1. Thrombolysis with alteplase as first-line therapy
  2. Emergency reoperative mitral valve replacement Correct answer.
  3. Percutaneous balloon mitral valvuloplasty
  4. Increase the warfarin dose and reassess in 48 hours

Explanation

Obstructive prosthetic valve thrombosis with cardiogenic shock is a surgical emergency requiring reoperation, because mortality without intervention is very high. Thrombolysis is generally reserved for patients at prohibitive surgical risk or for right-sided valve thrombosis. Balloon valvuloplasty is not appropriate for a mechanical prosthesis with thrombus.

Question 31Adult Cardiac Surgery

In an adult undergoing elective coronary artery bypass grafting, which conduit has the best long-term patency when used to bypass the left anterior descending artery?

  1. Radial artery
  2. Great saphenous vein
  3. Left internal thoracic artery Correct answer.
  4. Right internal thoracic artery

Explanation

The left internal thoracic artery has the highest long-term patency of the commonly used conduits to the left anterior descending artery, partly because its endothelial biology avoids the intimal hyperplasia seen in vein grafts. Saphenous vein grafts have lower late patency, and arterial alternatives are generally reserved for specific situations.

Question 32Adult Cardiac Surgery

During intra-aortic balloon counterpulsation, inflation of the balloon is timed to begin at which point in the cardiac cycle?

  1. At the peak of the T wave
  2. Immediately before the QRS complex
  3. At the dicrotic notch Correct answer.
  4. At the onset of ventricular systole

Explanation

Inflation during early diastole, timed to the dicrotic notch, raises aortic diastolic pressure and improves coronary perfusion; deflation before systole reduces afterload. The dicrotic notch corresponds to aortic valve closure.

Question 33Adult Cardiac Surgery

Which physical examination finding is most characteristic of severe aortic stenosis?

  1. Water-hammer pulse
  2. Bounding carotid pulses
  3. Widened pulse pressure
  4. Pulsus parvus et tardus Correct answer.

Explanation

Severe aortic stenosis produces a fixed left ventricular outflow obstruction, so the carotid upstroke is delayed and reduced in amplitude, known as pulsus parvus et tardus. Widened or bounding pulses point instead to aortic regurgitation.

Question 34Adult Cardiac Surgery

A 68-year-old man has asymptomatic severe aortic stenosis with an aortic valve area of 0.8 cm² and a mean gradient of 45 mm Hg. His left ventricular ejection fraction is 45%. Which management is most appropriate?

  1. Continue observation with annual echocardiography
  2. Start a statin and reassess in 1 year
  3. Refer for balloon aortic valvuloplasty
  4. Refer for aortic valve replacement Correct answer.

Explanation

In asymptomatic severe aortic stenosis, a left ventricular ejection fraction below 50% is a Class I indication for aortic valve replacement, even without symptoms. Observation, statin therapy, and balloon valvuloplasty are not definitive treatment for this patient.

Question 35Adult Cardiac Surgery

A 58-year-old man presents with sudden tearing chest pain and is found to have a Stanford type A aortic dissection. Which management is most appropriate?

  1. Emergent surgical repair Correct answer.
  2. Elective repair after 6 weeks of medical therapy
  3. Percutaneous coronary intervention
  4. Intravenous thrombolysis

Explanation

Stanford type A dissection carries an immediate risk of rupture, pericardial tamponade, and malperfusion, so emergent surgical repair is indicated. Medical rate and blood pressure control is only a bridge, and thrombolysis is contraindicated.

Question 36Adult Cardiac Surgery

A 55-year-old woman has symptomatic severe degenerative mitral regurgitation caused by isolated posterior leaflet prolapse. She has normal left ventricular function. Which operation is preferred?

  1. Percutaneous edge-to-edge repair as first-line
  2. Mechanical mitral valve replacement
  3. Mitral valve repair Correct answer.
  4. Bioprosthetic mitral valve replacement

Explanation

For isolated posterior leaflet prolapse with normal ventricular function, mitral valve repair is preferred because it preserves the native valve, avoids lifelong anticoagulation, and has excellent durability. Replacement is reserved for valves that cannot be repaired.

Question 37Adult Cardiac Surgery

A patient has 250 mL/h of bloody mediastinal chest tube output for 4 consecutive hours after coronary artery bypass grafting, with stable vital signs. Which next step is most appropriate?

  1. Transfuse platelets and reassess in 8 hours
  2. Return to the operating room for reexploration Correct answer.
  3. Perform bedside echocardiography and remove the chest tube
  4. Administer protamine and continue observation

Explanation

Chest tube output exceeding 200 mL/h for 4 consecutive hours is a standard trigger for reexploration after cardiac surgery. Stable vital signs do not exclude accumulating mediastinal blood or tamponade, and delay increases risk.

Question 38Adult Cardiac Surgery

A 45-year-old man with hypertrophic obstructive cardiomyopathy has exertional syncope and a resting left ventricular outflow gradient of 60 mm Hg despite maximally tolerated beta-blockade and disopyramide. Which intervention is most appropriate?

  1. Dual-chamber pacemaker placement
  2. Aortic valve replacement
  3. Surgical septal myectomy Correct answer.
  4. Alcohol septal ablation as first-line therapy

Explanation

Surgical septal myectomy is the standard treatment for drug-refractory obstructive hypertrophic cardiomyopathy because it directly relieves the subaortic gradient. Alcohol septal ablation is an alternative in selected patients, and pacemaker therapy is not definitive.

Question 39Adult Cardiac Surgery

A patient with a continuous-flow left ventricular assist device has increasing pump power consumption, reduced pulsatility, and new hemolysis. Which complication is most likely?

  1. Driveline infection
  2. Right ventricular failure
  3. Pump thrombosis Correct answer.
  4. Aortic insufficiency

Explanation

Continuous-flow left ventricular assist device pump thrombosis raises pump power, reduces pulsatility, and causes hemolysis as blood is sheared through a thrombosed rotor. Aortic insufficiency and right ventricular failure lower pulsatility but do not typically raise power or cause hemolysis.

Question 40Adult Cardiac Surgery

A 50-year-old man has chronic thromboembolic pulmonary hypertension with proximal organized thrombus in the main pulmonary arteries. Which operation is most appropriate?

  1. Inferior vena cava filter placement alone
  2. Balloon pulmonary angioplasty as first-line therapy
  3. Lung transplantation
  4. Pulmonary thromboendarterectomy Correct answer.

Explanation

Pulmonary thromboendarterectomy is the definitive treatment for accessible proximal chronic thromboembolic disease and can be curative. It is performed through a median sternotomy with cardiopulmonary bypass and intervals of deep hypothermic circulatory arrest.

Question 41Adult Cardiac Surgery

A 62-year-old man undergoes coronary artery bypass grafting. Six hours postoperatively he becomes hypotensive, with a blood pressure of 82/58 mm Hg, a heart rate of 118 beats/min, distended neck veins, and urine output of 10 mL/h. Chest tube output has abruptly stopped. Which diagnosis is most likely?

  1. Acute cardiac tamponade Correct answer.
  2. Systemic inflammatory response syndrome
  3. Tension pneumothorax
  4. Hypovolemic shock from under-resuscitation

Explanation

After cardiac surgery, tamponade can present with hypotension, elevated central venous pressure, tachycardia, and oliguria, and chest tube cessation may reflect clot occluding the drain. Bedside echocardiography is the key confirmatory test and shows cardiac compression or a pericardial collection. This presentation is not explained by simple hypovolemia because the venous pressures are elevated.

Question 42Adult Cardiac Surgery

A 70-year-old woman undergoes aortic valve replacement. On postoperative day 7 she has fever, sternal instability, and purulent drainage from the sternotomy. Which management is most appropriate?

  1. Surgical debridement and drainage Correct answer.
  2. Oral antibiotics and serial wound checks
  3. Reassurance because superficial wound infections are common
  4. Immediate sternal rewiring without debridement

Explanation

Deep sternal wound infection with sternal instability requires operative debridement of infected and necrotic tissue, drainage, and often muscle flap reconstruction. Antibiotics alone do not eradicate infected hardware or devitalized bone. Rewiring without debridement risks persistent mediastinitis.

Question 43Adult Cardiac Surgery

A 65-year-old man develops new-onset atrial fibrillation on postoperative day 2 after mitral valve repair. He is hemodynamically stable with a ventricular rate of 130 beats/min and no signs of ischemia. Which initial management is most appropriate?

  1. Initiation of flecainide without prior rate control
  2. Observation without treatment
  3. Immediate electrical cardioversion
  4. Rate control with a beta-blocker Correct answer.

Explanation

In a hemodynamically stable patient with postoperative atrial fibrillation, initial management focuses on rate control and assessment for anticoagulation. Electrical cardioversion is reserved for instability or ischemia. Flecainide is generally avoided in structural heart disease and should not be started without rate control.

Question 44Adult Cardiac Surgery

A 58-year-old man presents with uncomplicated acute type B aortic dissection. He has no malperfusion, rupture, or refractory pain. Blood pressure is 160/95 mm Hg. Which initial management is most appropriate?

  1. Emergency open descending aortic replacement
  2. Anti-impulse medical therapy Correct answer.
  3. Immediate thoracic endovascular aortic repair
  4. Intravenous thrombolysis

Explanation

Uncomplicated acute type B aortic dissection is managed initially with anti-impulse therapy to control blood pressure and reduce aortic wall stress. Thoracic endovascular repair is generally reserved for complicated dissection with malperfusion, rupture, or refractory symptoms. Open repair is not first-line for uncomplicated type B dissection.

Question 45Adult Cardiac Surgery

A 72-year-old woman with known aortic stenosis has a left ventricular ejection fraction of 30%, aortic valve area of 0.8 cm², and mean gradient of 22 mm Hg. Which finding on dobutamine stress echocardiography best indicates true severe aortic stenosis rather than pseudosevere stenosis?

  1. Mean gradient rises above 40 mm Hg with increased flow Correct answer.
  2. Aortic valve area increases to greater than 1.0 cm² during dobutamine
  3. New regional wall motion abnormality appears
  4. Left ventricular ejection fraction falls during infusion

Explanation

In low-flow, low-gradient aortic stenosis, dobutamine stress echocardiography distinguishes true severe stenosis from pseudosevere stenosis. True severe stenosis shows a rise in mean gradient above 40 mm Hg while the valve area remains small; pseudosevere stenosis shows the valve area increasing above 1.0 cm² as flow improves. A falling ejection fraction or new wall motion abnormality suggests ischemia or poor contractile reserve rather than valve severity.

Question 46Adult Cardiac Surgery

A 48-year-old man with a bicuspid aortic valve has an aortic root diameter of 52 mm. He has no symptoms and normal left ventricular function. Which management is most appropriate?

  1. Continue surveillance with echocardiography every 2 years
  2. Start a beta-blocker and repeat imaging in 1 year
  3. Isolated aortic valve replacement
  4. Aortic root replacement Correct answer.

Explanation

Bicuspid aortopathy with aortic root or ascending aortic diameter of 50 mm or greater is generally an indication for aortic root or ascending aortic replacement. At 52 mm, the risk of dissection or rupture outweighs elective surgical risk. Isolated valve replacement would leave the aneurysmal root untreated.

Question 47Adult Cardiac Surgery

A 66-year-old man with heparin-induced thrombocytopenia requires urgent coronary artery bypass grafting. He has a history of HIT and positive platelet factor 4 antibodies. Which intraoperative anticoagulation strategy is most appropriate?

  1. Warfarin started preoperatively
  2. Low-molecular-weight heparin boluses
  3. Unfractionated heparin with high-dose antithrombin
  4. Bivalirudin infusion Correct answer.

Explanation

Heparin-induced thrombocytopenia is an immune-mediated reaction that contraindicates both unfractionated heparin and low-molecular-weight heparin. Bivalirudin, a direct thrombin inhibitor, is a preferred anticoagulant for cardiac surgery in patients with HIT. Warfarin is not used for intraoperative anticoagulation and can cause venous limb gangrene in acute HIT.

Question 48Adult Cardiac Surgery

Ten minutes after protamine administration following cardiopulmonary bypass, a patient develops severe hypotension, bronchospasm, elevated pulmonary artery pressures, and right ventricular failure. Which immediate step is most appropriate?

  1. Give intravenous furosemide
  2. Start broad-spectrum antibiotics
  3. Stop protamine; give vasopressors Correct answer.
  4. Administer an additional intravenous protamine dose

Explanation

This presentation suggests a severe protamine reaction with pulmonary vasoconstriction and right ventricular failure. Management includes stopping further protamine and supporting the circulation with vasopressors and inotropes; reinstitution of cardiopulmonary bypass may be needed in catastrophic cases. Additional protamine can worsen the reaction.

Question 49Adult Cardiac Surgery

During aortic arch replacement requiring prolonged hypothermic circulatory arrest, which strategy most reliably provides cerebral protection?

  1. Selective antegrade cerebral perfusion with moderate hypothermia Correct answer.
  2. Deep hypothermia alone at 18°C without cerebral perfusion
  3. Retrograde cerebral perfusion with normothermia
  4. Intermittent rewarming to 32°C during arrest

Explanation

For prolonged hypothermic circulatory arrest, selective antegrade cerebral perfusion maintains oxygenated cerebral blood flow while moderate hypothermia reduces metabolic demand. This strategy limits ischemic neurologic injury and avoids the coagulopathy associated with unnecessarily deep hypothermia. Rewarming during arrest is harmful because it increases cerebral metabolic demand.

Question 50Adult Cardiac Surgery

A 55-year-old woman with acute massive pulmonary embolism has persistent hypotension despite fluid resuscitation and vasopressors. She has active gastrointestinal bleeding and cannot receive thrombolysis. Which treatment is most appropriate?

  1. Emergency surgical pulmonary embolectomy Correct answer.
  2. Systemic anticoagulation alone
  3. Catheter-directed thrombolysis
  4. Inferior vena cava filter alone

Explanation

Massive pulmonary embolism with hemodynamic instability requires reperfusion, and active gastrointestinal bleeding contraindicates thrombolytic therapy. Emergency surgical pulmonary embolectomy can relieve right ventricular obstruction and is appropriate in this setting. An inferior vena cava filter prevents recurrent embolism but does not treat the existing obstructing clot.