CSC Cardiac Surgery Certification Exam

Cardiac surgery encompasses a range of procedures performed on the heart and great vessels. The cardiac surgery certified nurse must understand the indications, techniques, and postoperative considerations for each procedure type.

Coronary artery bypass grafting (CABG) remains the most commonly performed cardiac surgical procedure. CABG involves harvesting conduits from the patient's own body to bypass stenotic or occluded coronary arteries. The internal mammary artery (IMA), also called the internal thoracic artery, is the preferred conduit for the left anterior descending artery due to its superior long-term patency rates exceeding 90% at ten years. The saphenous vein harvested from the leg serves as the most common conduit for additional grafts, though radial artery grafts are increasingly used for their improved patency compared to vein grafts.

On-pump CABG utilizes cardiopulmonary bypass (CPB) to maintain systemic perfusion while the heart is arrested. The ascending aorta is cross-clamped, and cardioplegia solution is delivered to induce cardiac arrest and provide myocardial protection. Off-pump coronary artery bypass (OPCAB) is performed on the beating heart without CPB, using mechanical stabilizers to immobilize the target coronary artery during anastomosis. OPCAB may reduce the inflammatory response associated with CPB and decrease neurological complications in select patients.

Valve surgery addresses stenotic or regurgitant cardiac valves. Aortic valve replacement (AVR) is indicated for severe aortic stenosis or regurgitation. Mechanical valves offer durability but require lifelong anticoagulation with warfarin. Bioprosthetic valves derived from porcine or bovine pericardial tissue do not require long-term anticoagulation but have limited durability, typically lasting 10-20 years. Transcatheter aortic valve replacement (TAVR) is now an alternative to surgical AVR across surgical risk groups, including low-risk patients. Post-procedure care centers on access-site bleeding and vascular injury, stroke, new conduction block, and paravalvular leak.

Mitral valve repair is preferred over replacement when anatomically feasible, as repair preserves the native valve apparatus and avoids the complications associated with prosthetic valves. Mitral valve replacement is performed when repair is not possible. The subvalvular apparatus, including chordae tendineae and papillary muscles, should be preserved when possible to maintain left ventricular geometry and function.

Aortic surgery involves repair or replacement of diseased segments of the aorta. Ascending aortic aneurysms exceeding 5.5 cm in diameter generally warrant surgical intervention due to increased rupture risk. Aortic dissection represents a surgical emergency requiring immediate intervention. Type A dissections involving the ascending aorta require emergent surgical repair, while Type B dissections involving only the descending aorta may be managed medically unless complications arise.

Combined procedures address multiple pathologies simultaneously. A patient may undergo CABG with concurrent valve replacement or repair. Combined procedures increase operative complexity and duration, requiring vigilant postoperative monitoring for complications.

Cardiopulmonary bypass temporarily assumes the functions of the heart and lungs during cardiac surgery. Understanding CPB physiology is essential for anticipating and managing postoperative complications.

The CPB circuit consists of venous cannulae draining blood from the right atrium or vena cavae, a reservoir, an oxygenator with integrated heat exchanger, a pump, an arterial filter, and an arterial cannula returning oxygenated blood to the systemic circulation via the ascending aorta or femoral artery. The perfusionist manages CPB under the surgeon's direction.

Hemodilution occurs when the patient's blood mixes with the crystalloid priming solution in the CPB circuit. Hematocrit typically decreases to 20-25% during bypass. While hemodilution reduces blood viscosity and improves microcirculatory flow, severe hemodilution may compromise oxygen delivery and is associated with adverse outcomes.

Hypothermia is commonly employed during CPB to reduce metabolic demands and provide organ protection. Mild hypothermia (32-35°C) is used for most procedures. Moderate hypothermia (26-32°C) or deep hypothermic circulatory arrest (DHCA) at temperatures below 20°C is employed for complex aortic surgery requiring periods of absent perfusion. Rewarming must be gradual and complete before separation from CPB to prevent afterdrop and its associated complications.

The systemic inflammatory response syndrome (SIRS) is triggered by blood contact with artificial surfaces, surgical trauma, ischemia-reperfusion injury, and endotoxin release. SIRS manifests as vasodilation, capillary leak, coagulopathy, and organ dysfunction. The magnitude of inflammatory response correlates with CPB duration.

Myocardial protection during CPB is achieved through cardioplegia, a solution delivered to arrest the heart and reduce myocardial oxygen consumption. Cardioplegia may be blood-based or crystalloid, delivered anterograde through the aortic root or retrograde through the coronary sinus. Cold cardioplegia reduces metabolic rate, while warm cardioplegia may improve metabolic recovery. Inadequate myocardial protection results in ischemic injury manifesting as myocardial stunning, arrhythmias, or infarction.

Separation from CPB requires adequate rewarming, correction of metabolic abnormalities, establishment of a stable cardiac rhythm, and sufficient myocardial contractility. Inotropic support may be required to facilitate separation. Protamine is administered to reverse heparin anticoagulation after CPB termination.

Low cardiac output syndrome (LCOS) occurs when the heart fails to generate adequate systemic perfusion following surgery. Causes include myocardial stunning, ischemia, infarction, arrhythmias, hypovolemia, tamponade, and excessive afterload. LCOS manifests as hypotension, oliguria, cool extremities, altered mentation, falling SvO2, and elevated lactate, usually with a cardiac index below 2.2 L/min/m². Management involves optimizing heart rate and rhythm (often atrial pacing at 80–100/min), optimizing preload, reducing afterload, supporting contractility with inotropes, and identifying reversible causes; mechanical support (IABP, short-term VAD, or ECMO) is added when drugs fail.

Vasoplegia is profound vasodilation after cardiopulmonary bypass with a normal or high cardiac index and a low SVR despite adequate filling. Risk factors include long bypass time and preoperative ACE inhibitors, angiotensin receptor blockers, or heparin. Treatment is norepinephrine with vasopressin added as a catecholamine-sparing agent; refractory cases may receive methylene blue (avoid with serotonergic drugs because of serotonin syndrome), hydroxocobalamin, or angiotensin II.

Right ventricular failure presents with a rising CVP, falling cardiac output, and a CVP equal to or higher than the PAOP. Management includes maintaining coronary perfusion pressure, avoiding hypoxia, hypercarbia, and acidosis, cautious volume, inotropes such as milrinone or epinephrine, inhaled pulmonary vasodilators (nitric oxide or epoprostenol), and AV-synchronous pacing.

Cardiac tamponade results from accumulation of blood or fluid in the pericardial space, compressing the heart and impeding diastolic filling. Classic signs include hypotension, elevated central venous pressure, muffled heart sounds, and pulsus paradoxus. However, postoperative tamponade may present atypically with localized clot compression. Echocardiography confirms the diagnosis. Treatment requires emergent drainage, either through reopening mediastinal tubes, percutaneous pericardiocentesis, or surgical exploration.

Postoperative bleeding requiring reexploration occurs in 2-6% of cardiac surgical patients. Risk factors include preoperative anticoagulation or antiplatelet therapy, prolonged CPB, complex procedures, hypothermia, and coagulopathy. Commonly used thresholds for surgical reexploration include chest tube output above 400 mL in the first hour, above 200 mL/hour for 2–4 consecutive hours, or any sudden large output or hemodynamic instability despite resuscitation; follow the surgeon's specific orders. Coagulopathy is corrected with blood products and agents guided by laboratory values and point-of-care viscoelastic testing.

Atrial fibrillation is the most common arrhythmia following cardiac surgery, occurring in 25-40% of patients. Peak incidence is postoperative days two through four. Risk factors include advanced age, history of atrial fibrillation, valve surgery, and withdrawal of beta-blockers. Atrial fibrillation increases stroke risk, prolongs hospitalization, and increases costs. Prevention strategies include continuing or resuming beta-blockers early, amiodarone prophylaxis in high-risk patients, and keeping potassium and magnesium replete.

Ventricular arrhythmias may indicate myocardial ischemia, graft failure, electrolyte abnormalities, or medication effects. After cardiac surgery, cardiac arrest is managed with the cardiac surgery advanced life support (CALS) protocol rather than standard ACLS; see Emergent Reopening of the Chest.

Vascular complications include femoral or radial access-site hematoma, retroperitoneal bleeding (back or flank pain, falling hemoglobin, hypotension after femoral cannulation or TAVR), limb ischemia from arterial cannulas or an IABP, and compartment syndrome (pain out of proportion, pain with passive stretch, tense compartment) that requires urgent fasciotomy.

Complete heart block may result from surgical trauma to the conduction system, particularly following valve surgery near the atrioventricular node. Temporary epicardial pacing wires provide rate support. Persistent heart block beyond seven days typically requires permanent pacemaker implantation.

Stroke complicates 1-3% of cardiac surgical procedures. Mechanisms include embolism of atherosclerotic debris, air, or particulate matter; hypoperfusion; and hemorrhage. Risk factors include advanced age, aortic atherosclerosis, atrial fibrillation, prior stroke, and prolonged CPB. Prevention strategies include epiaortic ultrasound to guide cannulation, maintaining adequate perfusion pressure, and avoiding hyperglycemia.

Acute kidney injury (AKI) occurs in 20-30% of cardiac surgical patients, with 2-5% requiring renal replacement therapy. CPB-associated factors include hypoperfusion, non-pulsatile flow, hemodilution, and inflammatory mediators. Preoperative renal dysfunction, diabetes, and hemodynamic instability increase risk. Prevention involves maintaining adequate perfusion pressure, avoiding nephrotoxins, and judicious fluid management. Severe AKI requiring dialysis carries mortality exceeding 50%.

Respiratory failure requiring prolonged mechanical ventilation occurs in 5-10% of patients. Causes include atelectasis, pneumonia, acute respiratory distress syndrome (ARDS), diaphragmatic dysfunction from phrenic nerve injury, and cardiogenic pulmonary edema. Prevention includes lung-protective ventilation strategies and early mobilization.

Sternal wound infection occurs in 1-4% of patients, with deep sternal wound infection (mediastinitis) carrying mortality of 10-25%. Risk factors include diabetes, obesity, bilateral internal mammary artery harvest, prolonged operative time, and reexploration for bleeding. Prevention involves glycemic control, appropriate antibiotic prophylaxis, and meticulous surgical technique. Treatment of mediastinitis requires surgical debridement, prolonged antibiotic therapy, and often reconstruction with muscle flaps.

Delirium affects 25-50% of cardiac surgical patients, particularly the elderly. Contributing factors include advanced age, preoperative cognitive impairment, prolonged CPB, sedative medications, sleep deprivation, and metabolic derangements. Delirium increases mortality, prolongs hospitalization, and may result in lasting cognitive impairment. Prevention involves minimizing sedation, promoting sleep, early mobilization, and reorientation strategies.

Preoperative risk stratification guides informed consent discussions and resource allocation. The Society of Thoracic Surgeons (STS) risk calculator estimates operative mortality and major morbidity for cardiac surgical procedures based on patient demographics, comorbidities, and procedural factors. The EuroSCORE II provides similar risk estimation in European populations.

High-risk features include advanced age, reduced ejection fraction, emergent surgery, redo sternotomy, renal dysfunction, chronic lung disease, peripheral vascular disease, diabetes, and combined procedures. Frailty, assessed through grip strength, gait speed, and functional status, independently predicts adverse outcomes beyond traditional risk models.

Preoperative optimization addresses modifiable risk factors. Smoking cessation for at least four weeks improves pulmonary outcomes. Glycemic control reduces infectious complications. Anemia correction through iron supplementation or erythropoietin-stimulating agents may reduce transfusion requirements. Nutritional optimization improves wound healing and functional recovery.