Anesthesia for cardiac surgery is a highly specialized discipline that plays a key role in the success of heart procedures. It aims to ensure the absence of pain, hemodynamic stability, and protection of vital organs throughout the operation. Cardiac surgery presents unique challenges due to the complex physiology of the heart and blood circulation, requiring careful anesthetic management.

In this article, we will explore the fundamental principles of cardiac anesthesia, the techniques used, the medications administered, the possible complications, and the recent advances in this field.

Fundamental principles of anesthesia in cardiac surgery

Anesthesia for cardiac surgery is based on several objectives:

• Bring the patient to a state of unconsciousness and analgesia without compromising cardiovascular function.
• Maintain stable hemodynamics by managing blood pressure and cardiac output.
• Ensure adequate oxygenation and ventilation throughout the procedure.
• Facilitate the use of cardiopulmonary bypass (CPB), if necessary.
• Optimize postoperative recovery and minimize complications.

Patients undergoing cardiac surgery often have comorbidities (hypertension, diabetes, renal failure, etc.), which makes their anesthetic management even more complex.

Preoperative patient assessment

Before cardiac surgery, a complete patient evaluation is essential:

a) Clinical assessment

• Medical and surgical history: heart disease, lung pathologies, previous operations.
• Physical examination: Assessment of cardiac and respiratory function.
• Airway assessment: Anticipate intubation difficulties.

b) Additional examinations

• Electrocardiogram (ECG): to detect rhythm disorders or signs of ischemia.
• Transthoracic (TTE) or transesophageal echocardiography (TEE): assessment of cardiac function and valvulopathies.
• Biological Assessment: Complete blood count, coagulation, renal and hepatic function, electrolyte balance.

c) Specific strategies according to the type of cardiac pathology

• Patients with heart failure require optimal volemic control.
• In the event of valvular heart disease, a detailed assessment of the pressure gradient is necessary.
• For coronary artery disease, an analysis of the risk of perioperative infarction is essential.

Anesthetic techniques used in cardiac surgery

General anesthesia is the reference technique for cardiac surgery. It is based on several stages.

a) Anesthetic induction

It involves administering anesthetic agents to put the patient to sleep. Commonly used medications include:

• Hypnotics: propofol, etomidate, or midazolam.
• Analgesics: fentanyl, sufentanil or remifentanil.
• Curarizing agents: rocuronium, cisatracurium to facilitate intubation.

Etomidate is often preferred in hemodynamically unstable patients because it has little effect on blood pressure.

b) Maintenance of anesthesia

During the procedure, anesthesia is maintained using:

• Volatile halogenated agents (sevoflurane, isoflurane) or propofol infusion.
• Potent analgesics (sufentanil, fentanyl) to limit the response to surgical stress.
• Curarizing agents for muscle relaxation.

c) Mechanical ventilation

• Patients are ventilated with a mixture of oxygen and air, with particular attention to positive end-expiratory pressure (PEEP) to avoid pulmonary atelectasis.

d) Intraoperative monitoring

The anesthesiologist must continuously monitor several parameters:

• Invasive blood pressure via a radial or femoral catheter.
• Electrocardiogram with ST segment analysis.
• Arterial blood gas to monitor oxygenation and acid-base balance.
• Transesophageal echocardiography (TEE) to assess cardiac function in real time.

Extracorporeal circulation and anesthetic management

In many cardiac surgeries, extracorporeal circulation (ECC) is used to replace the function of the heart and lungs.

a) Effects of CPB on anesthesia

• Controlled hypothermia to protect the brain and reduce oxygen consumption.
• Hemodilution due to the priming solution of the CPB circuit, possibly requiring transfusion.
• Inflammatory reaction due to contact of blood with artificial surfaces.

b) Anesthetic management during CPB (Cardiopulmonary bypass)

• Reduction of anesthetic depth, as anesthetic requirements are lower under hypothermia.
• Monitoring of cerebral perfusion to avoid neurological complications.
• Correction of acid-base and electrolyte disorders.

Postoperative management and possible complications

a) Extubation and recovery in intensive care

• Patients are generally transferred to cardiac intensive care for close monitoring.
• Early extubation (within 6 to 12 hours) is encouraged to reduce pulmonary complications.

b) Post-anesthesia complications

1. Hemodynamic: hypotension, arrhythmias, postoperative heart failure.
2. Respiratory: Pulmonary edema, atelectasis, pulmonary infection.
3. Neurological: postoperative confusion, stroke, cognitive disorders.
4. Renal: acute renal failure due to reduced perfusion during CPB.

Innovations and advances in cardiac anesthesia

a) Adjuvant locoregional anesthesia

• Thoracic epidural anesthesia and interfascial nerve blocks are increasingly used to improve postoperative analgesia.

b) Morphine-sparing techniques

• Use of dexmedetomidine and low-dose ketamine to reduce opioid consumption.

c) Artificial intelligence and advanced monitoring

• Development of AI algorithms to predict hemodynamic instability and optimize anesthetic management.

Conclusion

Anesthesia for cardiac surgery is a demanding specialty requiring rigorous and personalized patient management. Intensive monitoring, management of extracorporeal circulation, and optimization of postoperative recovery are key elements in ensuring the safety and success of the procedure. Thanks to recent advances, cardiac anesthesia continues to evolve to improve patient prognosis and comfort.

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