Cardiac Surgery

Anatomy and Physiology

The rib cage encases the chest organs, providing additional protection against external influences but making it more challenging for surgeons to access internal structures. The chest cavity is bordered by the ribs laterally, the sternum anteriorly, and the thoracic spine posteriorly. The chest cavity is divided into the bilateral pleural compartments and the mediastinum. The pleural spaces contain both wings of the lung. The mediastinum encloses several vital structures, including the esophagus, trachea, superior and inferior vena cavae, thoracic arteries, vagus nerve, azygos vein, lymphatic vessels, thymic remnant, and the pericardial sac containing the heart. The confined space within the pericardial sac places the heart at risk for tamponade physiology, which may occur when a hematoma compresses the heart, obstructing normal cardiac blood flow.[19]

As blood flows through the 4 chambers of the heart, it passes through 4 valves. Blood enters the right atrium via the superior and inferior vena cava, passes through the tricuspid valve into the right ventricle, and then flows through the pulmonary valve into the pulmonary circulation. The right side of the heart operates as a low-pressure system, unlike the left side, which supplies the systemic circulation and requires more myocardial tissue to generate higher pressure. Blood returns from the lungs through the 4 pulmonary veins into the left atrium, flows through the mitral valve into the left ventricle, and then passes through the aortic valve into the systemic circulation.[20] The aortic root comprises the sinuses of Valsalva, the interleaflet triangles, the sinotubular junction, and the aortic valve annulus, where the leaflets attach. The 3 leaflets are named according to their association with the right, left, and noncoronary cusps of the coronary arteries. As the components of the valve apparatus are interdependent, surgeons may need to address related structures to effectively treat the underlying pathology.

All cardiac valves are surrounded by an annulus, which poses challenges in creating artificial grafts that prevent leakage. Mitral valve replacement and the negative consequence of left ventricular outflow tract obstruction underscores the importance of understanding cardiac anatomy and physiology. While the aortic valve annulus is circular, the mitral valve annulus has a more crescent-shaped structure, necessitating more advanced prosthesis design and implantation techniques. Several artificial valve models illustrate this, each with distinct advantages and disadvantages related to anatomical, physiological, technical, and procedural factors. Additionally, the mitral valve features an annulus, and has anterior and posterior leaflets, each divided into 3 segments (A1 to A3 and P1 to P3). These segments are connected to the subvalvular apparatus, which includes chordae tendineae linking the valve leaflets to the papillary muscles.

Cardiac Electrical Conduction

The heart has an intrinsic rhythm that can be modulated by the autonomic nervous system: sympathetic stimulation accelerates the heart rate, whereas parasympathetic reaction slows it down. The cardiac electrical conduction is structured hierarchically, beginning with the sinus node, passing through the right atrium to the atrioventricular node, then traveling through the His bundle and Purkinje fibers to the ventricles. Understanding the anatomical and physiological aspects of this electrical activity is crucial for comprehending its clinical implications. Atrial fibrillation is common after cardiac surgery. The Maze procedure utilizes anatomical insights to disrupt uncontrolled atrial activity and address this condition. Additionally, the implantation of artificial heart valves can sometimes result in an atrioventricular block due to their proximity to the valve area.

Vessel Grafts

The quality of vessel grafts is vital for the outcome of CABG surgery. Surgeons can harvest various types of vessels, with arteries generally offering superior long-term durability compared to veins.[21] Preoperative assessment of graft quality is essential. Commonly used vessels include the left and right internal mammary arteries (LIMA and RIMA, respectively), radial arteries, and saphenous veins (saphenous vein grafts or SVGs). Due to vessel length, the RIMA is usually connected to the right coronary artery, while the LIMA is connected to the left anterior descending artery (LAD). Venous bypass grafts are commonly used to supply the posterior descending artery and the left circumflex artery. Additionally, venous grafts can be utilized to create bypasses to smaller branches, such as the diagonal branches of the LAD and the marginal branches of the left circumflex artery.[22]

Indications

Current guidelines outline the indications for cardiac surgery,[24][25] with general recommendations remaining consistent despite some variations. Decision-making is conducted by consensus, with cardiologists and surgeons collaborating as a heart team. Prior imaging—such as echocardiography, computed tomography (CT), or magnetic resonance imaging (MRI)—is routinely necessary to inform these decisions. 

Valvular Disease Indicators for Cardiac Surgery

In valvular heart disease, stenotic lesions and regurgitation are differentiated through a systematic classification approach. Generally, valvulopathies are categorized into a 3-step approach—mild, moderate, and severe— unlike the 4-step angiographic grading used in catheterization laboratories. Severe valve regurgitation or stenosis necessitates intervention, with options for replacement or reconstruction depending on the affected valve.[23]

With the introduction of transcatheter aortic valve replacement (TAVR) by Cribier in 2002, cardiovascular teams now decide between surgical and interventional treatments for severe aortic stenosis.[24][25] Severe aortic stenosis is defined as an opening area of <1 cm². The operative risk is a crucial factor, and TAVR has emerged as a transformative option, especially for patients who are inoperable or at high risk for traditional surgical aortic valve replacement (SAVR). The EUROScore or Society of Thoracic Surgeons (STS) score helps determine that patients with high operative risk should receive TAVR.[26] Lower risk scores allow for SAVR. High operative risk is associated with conditions such as porcelain aorta, liver cirrhosis (Child-Pugh classes B and C), previous CABG with LIMA, and frailty. Aortic valve endocarditis also necessitates SAVR. Despite advancements in device technology and procedural techniques, complications such as paravalvular leakage, conduction disorders, coronary ostial obstruction, and cerebrovascular events persist with TAVR. These complications can significantly impact patient health and short- and long-term survival. Additionally, the incidence of surgical reinterventions following TAVR is increasing, with endocarditis and structural valve deterioration emerging as significant long-term issues.[27]

Decision-making for aortic regurgitation involves careful pathophysiologic assessment. Operative treatment is required for aortic regurgitation associated with enlargement of the ascending aorta. Additionally, surgery is necessary for patients with symptoms due to severe aortic regurgitation. Asymptomatic patients with decreased left ventricular ejection fraction (LVEF) or increased left ventricular residual volumes (ie, LVEF <50%, left ventricular end-diastolic diameter >70 mm, or left ventricular end-systolic diameter >50 mm) should also undergo surgery. For severe aortic stenosis, echocardiographic characteristics include a vena contracta greater than 6 mm, pressure half-time less than 200 ms, effective regurgitant orifice area greater than 30 mm², and regurgitant volume more than 60 mL.

Mitral stenosis is primarily caused by rheumatic heart disease, which is rare in industrialized countries. Mitral regurgitation is treated based on its etiology.[28] Primary mitral regurgitation describes the structural pathology of the mitral valve apparatus itself, including leaflets, annulus, chords, and papillary muscles. Primary mitral regurgitation is classified according to Carpentier. Secondary or functional mitral regurgitation is caused by left ventricular dilatation, ischemia, and tethering. In contrast to aortic valve pathology, mitral valve lesions are primarily treated with repair techniques, including Alfieri edge-to-edge repair, resection, annuloplasty, and notochordal repair. Severe mitral regurgitation is defined by echocardiographic criteria such as a vena contracta greater than 7 mm, a regurgitant volume greater than 60 mL, and a regurgitant fraction of more than 50%.[29]

Multivalvular disease presents challenging decision-making due to the limited number of studies available.[30] When surgery for left heart disease is planned, secondary tricuspid regurgitation may be addressed simultaneously. However, the criteria for evaluating the right ventricle and tricuspid valve to determine the need for surgery remain unclear. A tricuspid valve annulus diameter of more than 40 mm suggests the need for tricuspid valve repair if mitral valve surgery is also planned.[31][32][33][34][35][36]

Additional Indicators for Cardiac Surgery

Cardiac surgery helps treat various cardiac rhythm disturbances by implanting devices such as pacemakers, including dual chamber devices for atrioventricular blocks, defibrillators for ventricular arrhythmia, and cardiac synchronization therapy for advanced heart failure. Cardiac surgery is also indicated for congenital heart disease, categorized into cyanotic and non-cyanotic lesions. Surgical options include closing ventricular and atrial septal defects. Specialized techniques have been developed for certain genetic conditions, such as Ebstein anomaly, tetralogy of Fallot, and transposition of the great vessels.

Cardiac and pulmonary pathologies may require cardiovascular surgical treatment. The most common benign heart tumor is an atrial myxoma, while sarcoma is the most frequent malignant cardiac tumor. Secondary metastatic tumors are more common than primary cardiac tumors and may cause obstructive or embolic symptoms. Pulmonary thrombendarterectomy may be necessary as a final treatment option for severe pulmonary embolism. In cases involving the thoracic aorta, surgery for dissection, aneurysm repair, and vessel graft replacement may be indicated.

Surgical revascularization can be a preferred option for treating coronary artery disease.[39] The cardiovascular team, comprising cardiologists and cardiac surgeons, makes management decisions collaboratively. Decision aids, such as syntax scores, assess the complexity of coronary artery disease and guide the choice between treatment by CABG and percutaneous coronary intervention (PCI). CABG is commonly indicated for left main stem and triple vessel disease. High-risk PCI patients with complex stenotic lesions may still undergo percutaneous treatment despite their increased operative risk.

Terminal heart failure, despite optimal medical therapy, can be managed with cardiac resynchronization therapy, implantation of assist devices, or heart transplantation.[37] Resynchronization therapy is indicated for patients with severe left ventricular dysfunction (LVEF <35%), the New York Heart Association (NYHA) classes III and IV symptoms, and a QRS complex duration greater than 130 ms on electrocardiogram (ECG). In periods of organ shortage, assist devices are increasingly utilized as a treatment option.[38][39] Studies have shown comparable outcomes between treatment options.[40] The REMATCH trial demonstrated a 2-year survival advantage with assist devices (23%) compared to medical therapy (8%). Slaughter et al found that continuous flow assist devices had a median support duration of 1.7 years versus 0.6 years for pulsatile flow left ventricular assist devices, with 88% and 79% of time spent outside the hospital, respectively.[41] Timing and patient selection for assisted device implantation or heart transplantation remain challenging. The INTERMACS classification and the Lietz-Miller score or the Destination Therapy Risk score are valuable tools for selecting appropriate patients.

Contraindications

During operation preparation, risk factors and contraindications are carefully evaluated. As cardiac surgery is typically reserved for advanced cardiac diseases, the benefits of the procedure often outweigh the risks when considered as a last treatment option. The EuroScore risk stratification tool is commonly used to assess operative risk, along with other tools such as the Parsonnet score and the STS score, to determine patient eligibility for surgery.[42][43][44]

Operations may be postponed in patients with unstable conditions. Determining the optimal timing for CABG in a patient with myocardial infarction can be challenging. In cases of endocarditis requiring valve replacement, surgery may need to be performed on a septic patient to control the infection.

Equipment

Cardiac surgery requires sophisticated equipment. For diagnostic purposes, tools such as pulmonary artery catheters, thermodilution techniques, pulse contour analysis, and ultrasound can be used to assess cardiac performance and disease. Critical issues related to cardiac output, volume responsiveness, and tissue oxygenation must be addressed.[45]

Equipment for treatment includes pacemakers, assist devices, ECMO, and CPB. The application of CPB started in the 1930s when Gibbon used an external pump circuit to sustain life in Boston, though initial setbacks interrupted its development. In 1951, Dogliotti introduced a partial heart and lung machine capable of a 1 L/min flow, marking a significant step forward in the evolution of CPB technology. Lewis first used the hypothermic technique in 1952 to reduce metabolic demand and minimize heart injury while closing an atrial septal defect. Lillehei introduced the concept of cross-circulation, temporarily replacing a dog's circulation by sharing it with another. A broader application became feasible with Kirklin's modification of the IBM Gibbon machine, significantly increasing survival rates. CPB enables heart venting and a clear operating area.[46]

However, CPB is associated with adverse effects, including a systemic inflammatory response triggered by exposure to the circuit.[47] Modifications to surgical techniques, such as reducing the duration and size of CPB and altering the tubing surface, have shown beneficial effects. The inflammatory response triggered by CPB is similar to that seen in infections, characterized by elevated inflammatory markers and shock-like symptoms. However, the timing differs, with the inflammatory response peaking on the first postoperative day and gradually decreasing afterward.[48] Cuthbertson described SIRS due to CPB as an "ebb and flow" process, with an initial phase of reduced metabolic activity lasting 2 to 3 days, followed by a hypermetabolic phase that can persist for over a week. To mitigate these effects, various strategies have been proposed, including the use of aprotinin, heparin-coated CPB circuits, hemofiltration, leukofiltration, and off-pump coronary artery bypass (OPCAB).[49][50]

The use of CPB and assist devices necessitates frequent coagulation tests. In addition to routine coagulation diagnostics, such as the international normalized ratio and partial thromboplastin time, more detailed laboratory assessments may be required. These can include rotational thromboelastography, activated clotting time, and the measurement of specific coagulation factors such as antithrombin III, fibrinogen, and factor VII, especially in cases of postoperative bleeding.[51]

Veno-venous ECMO includes an oxygenator, supporting the respiratory system by adding oxygen and removing carbon dioxide. Veno-arterial ECMO (VA-ECMO) provides both oxygenation and decarboxylation while partially replacing cardiac output. Cannulation for VA-ECMO can be placed centrally in the ascending aorta during sternotomy, producing antegrade flow, or peripherally with cannulas in the external iliac artery and vein. ECMO can be used as a bridge to recovery, a bridge to another intervention, or a bridge to transplant. The use of intra-aortic balloon pumps has decreased as studies failed to demonstrate a mortality benefit. Initially, the physiological consideration was improved diastolic coronary perfusion of the coronaries and pull effect during systole via counterpulsation of a balloon placed in the descending thoracic aorta.

Choosing the appropriate prosthetic heart valve for replacement is crucial. Mechanical valves, which offer greater resistance to structural degeneration, require lifelong anticoagulation and are generally recommended for younger patients. In contrast, bioprosthetic valves made from porcine or pericardial tissue do not necessitate anticoagulation but may experience earlier degeneration and require reoperation.[52] Bioprosthetic heart valves are typically indicated for women planning to have children and older patients. The Ross procedure, involving a pulmonic autograft for the aortic position, is another option for aortic valve replacement.[53]

Personnel

After completing medical school, graduates can apply for cardiac surgery training, which varies in length and content. For those with prior general surgical experience, an additional 2 years of specialization is required. Alternatively, 6-year training programs offer subspecialty training in areas such as minimally invasive surgery, adult and pediatric and congenital cardiac surgery, vascular surgery, endovascular interventions, general thoracic surgery, and heart failure surgery.

Training in cardiac surgery is highly competitive and demanding due to the specialty's evolving nature, an increasingly elderly and multimorbid population, working hour restrictions, and the introduction of new interventional methods. Recent evaluations have predicted shortages of healthcare professionals in various countries over the coming decades. The cardiac perioperative team comprises cardiac surgeons and extracorporeal technologists, cardiac anesthesiologists, cardiac intensive care unit (ICU) clinicians, surgical nurses, cardiologists, and radiologists, each with specialized training.

Preparation

When preparing a patient for cardiac surgery, the following evaluations should be conducted:

• Blood tests to assess various body functions, including kidney and liver function tests, coagulation, complete blood count, and electrolytes.
• ECG to check for regular cardiac rhythmic activity.
• Echocardiography and cardiac catheterization to detect coronary artery disease and valvulopathies.
• Chest x-ray or chest CT to visualize thoracic comorbidities and plan the operative technique.
• Ultrasound of the neck vessels to evaluate stroke risk.
• Ultrasound of lower extremity veins to assess potential grafts.
• CT imaging to evaluate vascular and bony structures.

Carotid Doppler ultrasound should be performed in patients with left main disease, peripheral vascular disease, carotid bruits, a history of cerebrovascular accident, and heavy tobacco use, as well as in patients aged 65 or older. If significant stenosis is detected, further testing may be required, and endarterectomy might be considered.

CT imaging can significantly improve CABG surgical planning by providing a comprehensive understanding of the surgical field, which aids in optimizing the procedure and assessing potential risks and outcomes. Each CABG approach—such as primary sternotomy, redo sternotomy, and minimally invasive thoracotomy—presents unique challenges and risks. A preoperative CT scan aids in defining these considerations. Additionally, CT and CT angiography, with or without intravenous (IV) contrast, provide a noninvasive method to assess vascular and bony structures, guiding surgical planning effectively.[54]

Anticoagulation during the perioperative period requires careful management and special consideration. Platelet-inhibiting drugs should be discontinued before surgery based on the medication type; for instance, clopidogrel should be stopped 5 days before the procedure, while ASA and heparin may be continued until the operation. The benefits of revascularization must be weighed against bleeding risks. Strategies to mitigate bleeding complications in patients requiring urgent surgery while on anticoagulants include OPCAB, tailored coagulation diagnostics and management, administration of coagulation factors and platelet transfusions, and the use of antifibrinolytic agents.[55][56][57][58][59]

Technique or Treatment

Open heart surgery traditionally involves accessing the heart by opening the thorax via sternotomy or upper hemisternotomy. CABG is among the most common surgical procedures globally. Once the pericardial sac is opened with an inverted T incision, while sparing both phrenic nerves, cannulation, CPB, and cardioplegia are applied, allowing the heart to be mobilized for identifying the target arteries. Epiaortic ultrasound is used to assess atherosclerosis of the ascending aorta. After harvesting the grafts, they can be connected directly or using a T-graft technique to the coronary arteries and the aorta. Following anastomosis, success is confirmed by assessing flow rates through the grafts. After completing CPB, the thorax is closed, and the sternum is secured with wires. Pleural and mediastinal suction drains are left in place for the postoperative period. Intraoperatively placed epicardial electrodes connected to an external pacemaker help manage rhythmic complications but are removed before hospital discharge.

OPCAB is particularly beneficial for patients with high operative risk [60] and significant atherosclerosis of the ascending aorta, as clamping during CPB can release thrombogenic material and potentially cause a stroke. The no-touch technique minimizes manipulation of the potentially thromboembolic endothelial surface of the ascending aorta by using the internal mammary or innominate artery. This approach requires stabilizers and positioners for precise anastomosis to the coronary vessels, making it especially useful for high-risk patients. For these patients, surgical LIMA-to-LAD anastomosis combined with later PCI to other affected arteries, as part of hybrid coronary staged revascularization, may offer advantages over conventional CABG.[61][62] Although the inflammatory response is similar between on-pump and off-pump surgery, off-pump procedures have been associated with reduced transfusion requirements and other benefits. While off-pump bypass may be feasible in up to 95% of CABG patients, it has been performed in only about 20% of surgical revascularization cases recently (see Image. Coronary Revascularization Procedures).

Minimally invasive surgery and endoscopic CABG involve smaller incisions, video guidance, and specialized instruments. These techniques require additional training and are available only at select centers. Patients may experience reduced surgical trauma and faster postoperative recovery with these approaches. Many procedures can be performed using minimally invasive techniques, and with the advent of robotic surgery, robotic systems have also become a part of the cardiac operating room.

The myocardium can be protected during cardiac surgery using cardioplegia and hypothermia.[63] Various cardioplegic solutions are available, and cardioplegia can be administered either anterogradely via the aortic root or retrogradely through the coronary sinus.[64][65][66] Brain protection is achieved by enhancing brain perfusion, reducing thrombogenicity through modifications to blood constituents, and administering appropriate anticoagulation.[67][68][69]

Several valve-repair techniques have been established, including bicuspidization, DeVega, and the clover technique for the tricuspid valve, as well as the Alfieri edge-to-edge, foldoplasty, neochordae, and sliding plasty technique for the mitral valve. Depending on whether the aortic valve needs to be replaced or preserved, aneurysms and dissections of the ascending aorta may be addressed using the David, Yacoub, or Bentall techniques.[70][71]

Complications

The overall mortality rate in cardiac surgery ranges from 2% to 3%. Significant complications include postoperative bleeding, stroke,[72][73] renal failure,[74] mesenteric ischemia, atrial fibrillation,[75] cardiogenic shock,[76] and respiratory distress. Postoperative bleeding and hemorrhagic shock, along with coagulation disorders like heparin-induced thrombocytopenia, contribute to 10% to 20% of national blood product usage in cardiac surgery. Acute kidney injury affects up to 18% of patients undergoing cardiac procedures, with approximately 2% requiring renal replacement therapy. The incidence of these complications can serve as a quality indicator and impact both reimbursement and patient decision-making.

A nationally representative study has shown an increase in the incidence of postoperative stroke complications following CABG, corresponding with a rise in overall baseline patient risks. Among 2,569,597 CABG procedures, ischemic stroke occurred in 47,279 patients (1.8%), with the incidence rising from 1.2% in 2004 to 2.3% in 2015 (P < .001). Patient risk profiles have worsened over time, with stroke patients exhibiting higher Charlson comorbidity scores. Stroke was independently associated with a 3-fold increase in in-hospital mortality, an extended hospital stay of approximately 6 days, and an increase in total hospitalization costs by about $80,000. The strongest predictors of stroke were age 60 years or older and female sex (both P < .001).[77]

Myocardial infarction following cardiac surgery is classified as type 5 myocardial infarction according to the universal classification. The incidence ranges from 5% to 10%. Diagnosing postoperative myocardial infarction can be challenging due to routinely elevated cardiac enzyme levels from surgical manipulation and symptoms influenced by the postoperative status. Therefore, alternative diagnostic modalities, such as ECG, echocardiography, and coronary angiography, are crucial for assessing bypass patency. Echocardiography may reveal septal wall motion abnormalities that are not necessarily related to myocardial ischemia. Refractory shock and arrhythmias are highly suggestive of myocardial infarction. Myocardial infarction following CABG can be classified into graft-related and non-graft–related categories. Early graft dysfunction occurs in up to 3% of cases. Non-graft-related causes include inadequate myocardial protection and embolization. Treatment strategies for type 5 myocardial infarction include conservative medical treatment, PCI, and redo CABG.[78][79][80]

Following mitral valve replacement, left ventricular outflow tract obstruction can occur, characterized by systolic anterior motion of the anterior mitral leaflet. Treatment is approached in a stepwise manner, beginning with beta-blockers, increasing afterload with fluids, allowing hypertension, and, if necessary, proceeding to reoperation. Surgical techniques for reoperation include edge-to-edge repair, posterior leaflet shortening, short neochord, sliding plasty, and ellipsoid excision of the anterior leaflet.[81] Preoperative risk factors for this complication include a thick basal interventricular septum, a small left ventricle, a short distance between the interventricular septum and the mitral leaflet coaptation point, a tall posterior leaflet, and an aorta-mitral angle of less than 120 degrees.[82][83]

Postoperative pain management is crucial in cardiac surgery due to the intense stress and discomfort associated with these procedures. Ensuring patient comfort and calmness is vital for overall well-being, as it supports the immune response to the new graft and ensures the proper functioning of the heart, which in turn impacts the health of all other organs in the body. Effective postoperative pain management in cardiac patients is crucial for both medical professionals and patients, as it can significantly impact recovery and survival. Research shows that cardiac patients often experience their most intense postoperative pain about an hour after extubation. During this period, the highest doses of analgesics are typically administered to manage pain effectively. Pain intensity generally decreases over time, reaching its lowest point approximately an hour after the patient is transferred from the ICU to the ward.[84]

A range of early mobilization strategies is available for post-surgery patients, and while many have proven effective in enhancing recovery, optimal protocols are still under investigation. Early mobilization is crucial for improving outcomes after cardiac surgery and is now standard practice in many hospitals. This approach has been shown to safely and effectively enhance tissue perfusion, preserve muscle strength and mass, reduce the risk of pulmonary complications, shorten hospital stays, improve quality of life, and decrease mortality rates. Additionally, early mobilization has been found to reduce the incidence of delirium, a significant contributor to cognitive impairment associated with ICU stays.[85]

After a sternotomy, patients are typically advised to restrict certain activities to allow the sternum sufficient time to heal and prevent complications from physical exertion. These guidelines, often referred to as "sternal precautions," generally include avoiding lifting, pushing, or pulling objects weighing more than 5 to 10 pounds, driving, or using the arms to assist with sitting or standing. Patients are also encouraged to protect their chest by crossing their arms over it when moving or coughing. These precautions are usually recommended for up to 12 weeks post-surgery until the sternum fully recovers. However, some experts have raised concerns that these restrictions may be overly limiting, potentially leading to issues such as muscle atrophy and difficulty resuming daily activities.

A new movement protocol, "Keep Your Move in the Tube," is designed for patients recovering from sternotomy. This focuses on limiting arm extension to reduce strain on the healing sternum. The protocol emphasizes minimizing humeral movement to avoid tension on the surgical site. This approach is rooted in ergonomics and emphasizes patient education rather than strict directives. This encourages patients to keep their upper arms close to their body, as if modifying their movements within an imaginary tube around the torso. This helps avoid placing excessive stress on the sternum while allowing for functional movement.[86] Fever, edema, and increased inflammatory markers are commonly observed in postoperative patients, making it challenging to differentiate between confirmed infections and evolving sepsis.[87] The time course can give additional information. If signs and symptoms of infection appear after the second or third postoperative day, further investigation for infection should be initiated.[88]

Perioperative antibiotic prophylaxis is essential to reduce the risk of postoperative infections. Guidelines generally recommend administering cephalosporins during the 24 to 48-hour perioperative period. Fortunately, deep sternal wound infection is a rare complication of cardiac surgery, occurring in 0.4% to 4% of cases. However, if left untreated, it can progress to mediastinitis, which carries a significant mortality risk. Treatment for deep sternal wound infection involves pathogen-specific antibiotics (with common strains including Staphylococcus aureus or S epidermidis, often treated with clindamycin or according to resistance patterns), surgical exploration, and negative-pressure wound therapy.

The exact cause of postoperative cognitive decline remains unclear but is believed to be related to the body's stress and inflammatory responses to surgery and anesthesia. Postoperative cognitive impairment involves a reduction in the ability to orient oneself, focus, perceive surroundings, maintain consciousness, and make decisions. Risk factors for developing this condition include advanced age, female gender, significant blood loss, and elevated creatinine levels following surgery. Cognitive impairment is a common complication after surgery, with patients undergoing CABG being particularly vulnerable. A systematic review and meta-analysis revealed that cognitive impairment was observed in over 40% of patients within the first 4 days after CABG surgery. This rate decreased to about 25% at the 1-year mark but increased again to around 40% between 1 and 5 years after surgery. In the long term, beyond 5 years post-surgery, cognitive impairment was reported in 16% of patients—a rate notably lower than other long-term estimates, likely due to patient attrition and mortality during the follow-up period.[85][89]

Although rare, coronary obstruction is a potentially devastating complication of TAVR, most frequently occurring at the left coronary artery ostium. Detection can be challenging, as some patients may not exhibit noticeable clinical symptoms. Research indicates that a significant increase in peak diastolic flow velocity in the left main coronary artery is associated with substantial stenosis in these lesions.[90] Depending on hemodynamic stability, the patient's symptoms, and ECG findings, PCI or surgical revascularization may be indicated. If a coronary ostial iatrogenic injury occurs during surgical AVR, it is generally preferable to perform surgical revascularization rather than attempt to repair or reconstruct the coronary ostium.

Clinical Significance

Cardiac surgery is crucial for cardiovascular health, addressing the growing prevalence of cardiovascular diseases driven by epidemiologic transitions, such as atherosclerosis, hypertension, and lifestyle risk factors. In the United States, cardiac surgery accounts for 1% to 2% of the healthcare budget, with an average inpatient cost of $40,000, totaling approximately $20 billion. The rising demand for specialized healthcare professionals in cardiology and cardiac surgery underscores the need for increased expertise in these fields.[91]