Typically in elective cardiac surgery, and even in many emergency cases, the surgical diagnosis and operative plan have been established in advance by history, physical examination, and diagnostic testing. The patient presenting for heart surgery, by definition, has compromised cardiopulmonary function and has probably already suffered some degree of damage to other organs. The fundamental paradox of cardiac surgery is that the planned operation increases the risk of further damage to other organ systems, yet the operation itself presumably represents the best chance to “optimize” the patient’s overall condition. The substantial logistical and economic resources called upon by a cardiac operation impose additional pressure to develop a perioperative risk management strategy without postponing or canceling surgery.

Therefore, the goal of preoperative evaluation should be to clarify any preexisting conditions known to be associated with an increased risk of perioperative morbidity and mortality. Among these are:

Cardiac implantable electronic devices consist of permanent pacemakers, which supplement or replace the heart’s native conduction system, and implantable cardioverter defibrillators (ICDs), which provide tachycardia therapy. Approximately three million people worldwide currently live with a pacemaker. In the United States alone, roughly one million people have a pacemaker, and nearly 200,000 new pacemakers are implanted annually. Pacemakers and ICDs are implanted for a wide variety of conduction disorders and ischemic conditions (Table 26.4). The increasingly widespread use of these devices presents special challenges for perioperative management.

In addition to evaluating and optimizing coexisting conditions, preoperative evaluation of a patient with an implanted device should include determining the type of device, indication for placement, and currently programmed settings (Table 26.5). This information can frequently be obtained from the patient (wallet card) or the physician managing the device. A chest radiograph can help determine the device type by showing the number and location of pacing electrodes and shock coils. Also, the generator may also be identified by a radiopaque manufacturer logo and serial number. Locating the coronary sinus lead on a biventricular pacemaker or ICD can help avoid dislodgment during central line placement.

Nonetheless, interrogation with a programming console remains the only reliable means of evaluating assessing device settings and predicted battery life. Under ideal circumstances, all patients with a pacemaker or ICD should undergo preoperative device interrogation, not only to determine proper function but also to facilitate proper intraoperative management by the anesthesia team. However, this may not be possible in all situations, such as in emergency surgery.

Electromagnetic interference (EMI) from surgical electrocautery can be detected by the device and interfere with its normal function. Monopolar electrocautery (Bovie) creates an arc of electrical current from the single handheld electrode to the adhesive return pad; this current can threaten any electrical device or metallic implant in its path. In contrast, bipolar electrocautery confines the current between the two handheld electrodes and is preferable in these patients. If monopolar electrocautery is required for the operation, then the return pad should be placed in a location that prevents the electrical arc from crossing the device generator and leads. All patients with ICDs should have antitachycardia therapy disabled prior to surgery with monopolar electrocautery.

The sheer variety of devices and programming modes currently available makes formulaic preoperative management difficult. For example, it is commonly assumed that a magnet will convert a pacemaker to asynchronous pacing and disable antitachycardia therapy when applied to an ICD. However, magnet effects vary significantly depending on the manufacturer, model, and even specific device settings. Even when indicated, magnet placement is an unreliable technique for changing device therapy. Obesity, perspiration, patient movement, surgical positioning, and other implanted devices can interfere with proper magnet contact; loss of contact may not be readily apparent to the clinician, as the pacing function of the device would not be changed. The anesthesia team should test the magnet’s effect prior to the start of surgery, paying close attention to whether the preprogrammed asynchronous pacing rate is sufficient, particularly in patients with compromised myocardial function.

Postoperatively, any device that was reprogrammed prior to surgery should be interrogated and reset appropriately. Most manufacturers also recommend a postoperative interrogation to confirm proper device function and adequate battery life after exposure to electrocautery or other EMI. In addition, changes in the patient’s functional status after surgery may warrant new device settings to maintain adequate cardiac output and tissue oxygen delivery.

In many centers, anesthesiologists provide perioperative care for patients undergoing pacemaker and ICD placement and other electrophysiology procedures (e.g., catheter ablation of supraventricular arrhythmias). These procedures typically involve superficial tissue dissection with local anesthetic infiltration for pocket formation or catheter placement. The majority of these cases can be performed under deep sedation with spontaneous ventilation, rather than general endotracheal anesthesia. However, specific events during the procedure, such as cryoablation or ICD test shocks, are quite painful, so adequate analgesia and amnesia should be ensured. Because these procedures can be very lengthy, providers should be vigilant for ischemia of dependent body parts, atelectasis, excessive sedation, and airway obstruction. Intravenous lidocaine, often used to reduce the burning associated with propofol administration, has antiarrhythmic effects that may interfere with planned electrophysiologic studies and should probably be avoided. An acute fall in blood pressure may indicate pericardial tamponade resulting from cardiac perforation with a catheter or device lead, a situation that may require emergent surgical intervention.

Transesophageal echocardiography (TEE) has become an integral tool in the anesthetic management of cardiac surgical patients. Perioperative TEE allows the echocardiographer to diagnose intracardiac pathology (Table 26.6), direct the surgical procedure, and assess results and complications. In addition, TEE allows continuous intraoperative monitoring of cardiac function during cardiac and noncardiac operations. It is particularly useful for intrathoracic surgeries, during which transthoracic echocardiography would not be feasible.

TEE employs a long probe inserted into the patient’s esophagus (Fig. 26.6). A piezoelectric crystal at the tip of the probe emits a plane of ultrasound waves that reflect off different structures in relation to their tissue densities. The probe detects and processes these reflected waves to acquire an image. The imaging plane can be rotated up to 180° without moving the probe (multiplaning), thus allowing a structure to be imaged from multiple angles. The probe tip can be flexed in different directions, and the probe itself can be rotated or moved to different positions in the esophagus (mid-esophageal and upper esophageal windows) or stomach (transgastric and deep transgastric windows). Manipulating the probe in these ways can produce a comprehensive examination of the entire heart and many other intrathoracic structures (Fig. 26.7). The ascending aorta and transverse arch are not well visualized by TEE because the left mainstem bronchus passes between the esophagus and ascending aorta, impeding penetration of ultrasound waves. Recent technological advances have produced TEE probes capable of real-time three-dimensional imaging.

Absolute contraindications to TEE include perforations, stricture, or masses that can interfere with or be exacerbated by probe manipulation (Table 26.7). A TEE exam can be performed in a patient with relative contraindications provided the anticipated benefits of TEE monitoring outweigh the risks. For example, in a patient with esophageal varices and bacterial endocarditis, the risk of esophageal bleeding associated with TEE probe placement may be outweighed by the anticipated benefit of assessing the patient for intracardiac vegetations or prosthetic valve dehiscence. Alternatively, in the setting of relative contraindications, TEE can be performed with appropriate modifications (e.g., avoiding transgastric windows in a patient with a subtotal gastrectomy). An epicardial or epiaortic probe can also be handed off onto the sterile surgical field to obtain supplementary images. Epiaortic echocardiography remains the most sensitive and specific modality for visualizing calcifications in the ascending aorta that may preclude cannulation.

The overall complication rate of intraoperative TEE is very low (approximately 0.2 %) and can be minimized by careful patient preparation and probe manipulation (Table 26.8). Prior to inserting the TEE probe, an orogastric tube can be passed into the esophagus to determine if there are any strictures or other obstructions that would preclude safe passage of the larger TEE probe. Suctioning the orogastric tube before removing it will also evacuate stomach contents that can interfere with obtaining high-quality TEE images in the transgastric windows. To reduce the risk of esophageal rupture, all other esophageal instruments (e.g., esophageal temperature probes) should be removed before placing the TEE probe. The probe should never be forced blindly against resistance. If necessary, direct laryngoscopy and careful deflation of the endotracheal tube cuff can help facilitate probe placement. A bite block should be used to help protect the teeth and oral soft tissues from damage. The probe should be inspected and moved periodically during the operation to prevent pressure injury to the lips and gums. Inadequate rinsing of cleaning solutions from the probe can lead to chemical burns on oral soft tissues.

Stimulation from inserting and manipulating the TEE probe can produce adverse hypertension and tachycardia. Sufficient depth of anesthesia, analgesia, and vasoactive therapy should be ensured to avoid myocardial ischemia or heart failure from probe manipulation. Because the thoracic aorta passes close to the esophagus, large thoracic aneurysms can compress the esophagus, causing dysphagia. Probe insertion in this situation increases the risk of aortic rupture. The preoperative CT scan should be examined in advance for signs of esophageal impingement or deviation.

Perhaps the most underappreciated and dangerous consequence of intraoperative TEE is provider distraction. The eagerness to obtain optimal views and elucidate complex structures on the TEE exam can cause the operator to neglect important changes on patient monitors or the surgical field. The provider should never forget that performing a comprehensive TEE exam is only one aspect of complete anesthetic management for cardiac surgery. For this reason, it is desirable to have one anesthesia provider concentrate on monitoring and tending to the patient while another performs and interprets the TEE exam.

The National Board of Echocardiography (NBE) has developed processes by which anesthesiologists, depending on their level of training and case experience, can work toward certification in perioperative TEE. The recent introduction of basic certification affirms the value of TEE as a useful hemodynamic monitor in the noncardiac operative setting. Basic certification is intended to prepare providers, including those without specialized training in cardiac anesthesiology, to use TEE primarily for intraoperative monitoring of hemodynamic instability and guidance of inotropic and vasoactive support. Global and regional left ventricular function, right ventricular function, hypovolemia, qualitative valvular function, pulmonary embolism, air embolism, pericardial effusions, thoracic trauma, and basic septal defects can be assessed within the scope of the basic TEE examination. Advanced certification expands the scope of training to encompass complex valvular lesions, prosthetic devices, congenital defects, and other complex intrathoracic pathology. Advanced certification also prepares the provider to provide diagnostic guidance for cardiac surgical and transcatheter procedures.

More than in any other intraoperative settings, patients undergoing cardiac surgery have disease conditions that put them at risk of decompensating with very little warning. The overarching philosophy of cardiac perioperative care, then, is to be ready to respond to a sudden decline in the patient’s condition at any time. Anesthesia providers should always be prepared to support any necessary resuscitative maneuvers, including emergency sternotomy and CPB. It is prudent to have bolus and infusion preparations of an inotrope, a vasoconstrictor, and a vasodilator ready to use for every case, plus sufficient heparin to commence bypass (Table 26.9).

Preventing adverse hemodynamic responses to anesthetic and surgical interventions, an important goal in any operation, is especially critical in cardiac surgery (Table 26.10). Preoperative sedation and induction of general anesthesia can lead to decreases in myocardial function and peripheral vascular resistance that may be poorly tolerated in cardiac patients. Pain and increased sympathetic stimulation from incision, sternotomy, and aortic cannulation can precipitate tachycardia, hypertension, or dysrhythmias, all of which can lead to ischemia and heart failure in patients with compromised cardiac function. One useful technique is to assess preoperatively the range of vital signs within which the patient is asymptomatic, comfortable, and free of ischemia (e.g., during physical activity or stress testing), and then use this range as a goal for maintaining blood pressure and heart rate in the operating room.

Patients about to undergo heart surgery are likely to be very anxious, but what may be an appropriate intravenous dose of midazolam or fentanyl for another patient may be excessive for a patient with compromised cardiac function. As with any surgery, clinical judgment rather than just routine practice should be used to decide upon the need for premedication prior to surgery.

Ideally, patients should not be premedicated until they arrive in a location, such as the operating room or a preoperative holding area, where trained anesthesia personnel can monitor them continuously. Slow titration is desirable to prevent large swings in blood pressure and heart rate. Judicious premedication to sedate the patient can reduce the dosage of induction drugs required to achieve general anesthesia. Special care should be taken in patients with severe heart failure or with severe or symptomatic aortic stenosis, as they may be unable to compensate adequately for even small decreases in systemic vascular resistance. Medications that can be used for premedication include midazolam, diazepam (5–10 mg PO, the night before), morphine (0.15 mg/kg) plus scopolamine 0.2–0.3 mg intramuscularly (IM), or hydromorphone 1–2 mg IM. It should be remembered that scopolamine can cause confusion in the elderly, while the combination of a benzodiazepine and an opioid can have synergistic effects, which warrant reduction in dosage.

Standard noninvasive monitors and supplemental oxygen should be applied to the patient both in the preoperative holding area and upon arrival in the operating room. Induction of general anesthesia can cause rapid, detrimental changes in blood pressure. Therefore, continuous blood pressure monitoring is highly desirable, and an arterial line should be placed prior to induction. Before attempting a radial or brachial arterial line in a patient undergoing CABG, the anesthesia provider should confirm that it will not be in the same arm as any planned radial artery graft harvest. Patients undergoing aortic surgery may require multiple arterial lines in different locations (e.g., femoral and right radial arteries) depending on where the crossclamp will be placed during surgical repair.

Central venous access is also useful prior to induction to facilitate fluid management and vasoactive infusions. In the absence of intervening pathology, CVP is equivalent to right atrial pressure and can be affected by circulating blood volume, peripheral venous tone, and right ventricular function. Placing a central line can be deferred until after induction if the patient has an existing large-bore intravenous line or is unlikely to tolerate being conscious and stationary for the procedure. However, for patients in emergency situations with adequate large-bore access, central line placement and monitoring should not delay anesthetic induction, prompt opening of the chest, surgical control of bleeding, or initiation of bypass.

Traditionally, cardiac surgery was considered an indication in itself for the placement of a pulmonary artery (PA, or Swan-Ganz) catheter. The PA catheter allows measurement of pressures in the right ventricle and pulmonary artery, transvalvular pressure gradients across the tricuspid and pulmonic valves, and calculation of systemic and pulmonary vascular resistance. These values can help assess filling pressures throughout the heart and assist in the diagnosis and treatment of right heart failure and pulmonary hypertension. Thermodilution catheters also allow measurement of cardiac output, either intermittently or continuously, and sampling of mixed venous blood to assess total body oxygen extraction.

Several recent studies have questioned the utility of routine PA catheterization, suggesting an association with worse outcomes and even increased mortality. PA catheter data can greatly assist in hemodynamic management, especially in the postoperative setting without ready access to TEE equipment or trained operators, but this data should be evaluated in the context of the patient’s overall clinical status. TEE and other less invasive methods of cardiac output monitoring can be valuable adjuncts or, in many cases, alternatives to the PA catheter. In low-risk patients with well-preserved left ventricular function undergoing CABG, the PA catheter is unlikely to provide sufficient benefit to outweigh the risks of insertion. Placing a PA catheter is likely to yield more benefit in patients with known or anticipated right heart failure, pulmonary hypertension, severe valvular abnormalities, or contraindications to TEE.

Anesthetic induction in cardiac patients requires navigating a careful balance between avoiding hypotension and attenuating responses to laryngoscopy, TEE probe insertion, and surgical incision. Over the past several years, a variety of anesthetic techniques have been used successfully. As with premedication, choosing among different anesthetic regimens should not be a rote practice but rather a thoughtful consideration of their individual benefits and disadvantages in the context of the patient’s own physiologic profile.

Induction with high doses of opioids became popular in the 1970s and 1980s because of their hemodynamic stability and excellent attenuation of stress response when compared to the inhaled agents of the time (e.g., halothane). Induction can be achieved with large doses of morphine (1–2 mg/kg), fentanyl (50–100 mcg/kg), or sufentanil (10–25 mcg/kg). The accompanying vagotonic effects and chest wall rigidity can be counteracted to some extent with timely administration of pancuronium. However, pure high-dose opioid induction without an accompanying amnestic agent (such as midazolam or scopolamine) is associated with an unacceptably high occurrence of intraoperative awareness and postoperative recall. Also, prolonged postoperative respiratory depression lasting up to 12–24 h delays weaning from mechanical ventilation. Although high-dose opioid induction has been mostly supplanted by other techniques, it is still a useful option in high-risk patients who are expected to require prolonged postoperative ventilation.

The impetus to reduce the duration of postoperative ventilation has increased interest in combined intravenous-inhaled anesthesia techniques. Anesthesia for cardiac surgery can be induced with nearly any intravenous amnestic agent, such as etomidate (0.1–0.3 mg/kg), propofol (0.5–2 mg/kg), thiopental (1–2 mg/kg—no longer available), or ketamine (1–2 mg/kg). Etomidate is commonly used for cardiac inductions because myocardial contractility and preload remain relatively well preserved compared to other agents. Propofol can significantly reduce cardiac output and systemic vascular resistance, while thiopental can reduce cardiac preload via increased venous pooling. Nonetheless, propofol and thiopental are useful induction agents in hemodynamically robust patients, provided they are titrated slowly to achieve the desired effect with less medication. Ketamine stimulates the sympathetic nervous system, increasing heart rate and blood pressure. This makes ketamine the favored induction agent in patients with cardiac tamponade or severe hypovolemia, but the increase in heart rate can worsen myocardial ischemia. Ketamine can also depress myocardial function in patients with depleted catecholamine levels.

Anesthesia can be maintained with an inhalational agent, continuous opioid or sedative infusions, or a combination of these techniques, depending on hemodynamic stability and expected time to extubation postoperatively. If total intravenous anesthesia is used, the infusions should be delivered through a line that will not be obstructed by cannulation snares; alternatively, infusions can be given directly through the CPB machine during bypass. The inspired oxygen concentration can be titrated to oxygen saturation readings from the pulse oximeter or arterial blood gases. Many providers choose to use 100 % oxygen to maximize inspired oxygen tension, particularly in patients with known or evolving ischemic disease. An air–oxygen mixture can help prevent absorption atelectasis and reduce the risk of oxygen free radical toxicity from prolonged ventilation. Nitrous oxide is typically avoided because it decreases the maximum inspired oxygen concentration, stimulates catecholamine release, increases pulmonary vascular resistance, and enlarges air emboli.