Anesthetic considerations

The determinants of the functional severity of the ventricular obstruction in obstructive HCM are (1) the systolic volume of the ventricle, (2) the force of ventricular contraction, and (3) the transmural pressure distending the LVOT.

Large systolic volumes in the ventricle distend the LVOT and reduce the obstruction, whereas small systolic volumes narrow the LVOT and increase the obstruction. When ventricular contractility is high, the LVOT is narrowed, increasing the obstruction. When aortic pressure is high, the increased transmural pressure distends the LVOT. During periods of decreased afterload and hypotension, however, the LVOT is narrowed, resulting in greatly impaired cardiac output often associated with significant mitral regurgitation. As the ventricle hypertrophies, ventricular compliance decreases, and passive filling of the ventricle during diastole is impaired. The ventricle becomes increasingly dependent on the presence of atrial contraction to maintain an adequate ventricular end-diastolic volume. Monitoring should be established that allows continuous assessment of these parameters, particularly in patients in whom the obstruction is severe.

In patients with symptomatic obstructive HCM presenting for surgery, an indwelling arterial catheter for beat-to-beat observation of ventricular ejection and continuous blood pressure (BP) monitoring should be placed before anesthesia induction. Transesophageal echocardiography (TEE) provides useful data on ventricular function and filling, the severity of LVOT obstruction, and the occurrence of SAM and mitral regurgitation. A pulmonary artery catheter (PAC), once more widely used, has not shown to improve outcome. Its use may be helpful in guiding treatment options, especially in patients with obstructive HCM undergoing major surgery with large fluid shifts.

Special consideration should be given to those features of the surgical procedure and anesthetic drugs that can produce changes in intravascular volume, ventricular contractility, and transmural distending pressure of the outflow tract. Decreased preload, for example, can result from blood loss, sympathectomy secondary to spinal or epidural anesthesia, use of potent volatile anesthetics and nitroglycerin, or postural changes. Ventricular contractility can be increased by hemodynamic responses to tracheal intubation or surgical stimulation. Transmural distending pressure can be decreased by hypotension secondary to anesthetic drugs, hypovolemia, or positive-pressure ventilation. Additionally, patients with obstructive HCM do not tolerate increases in heart rate. Tachycardia decreases end-diastolic ventricular volume, resulting in a narrowed LVOT. As noted earlier, the atrial contraction is extremely important to the hypertrophied ventricle. Nodal rhythms should be aggressively treated, using atrial pacing if necessary.

Halothane, now a historical drug and no longer available in the United States, had major hemodynamic advantages for the anesthetic management of patients with obstructive HCM. Its advantages were to decrease heart rate and myocardial contractility. Of the inhalational anesthetics, halothane had the least effect on systemic vascular resistance (SVR), which tended to minimize the severity of the obstruction when volume replacement was adequate. Sevoflurane decreases SVR to a lesser extent than isoflurane or enflurane and thus may be preferable. Agents that release histamine, such as morphine, thiopental, and atracurium, are not recommended because of the resulting venodilation. Agents with sympathomimetic side effects (ketamine, desflurane) are not recommended because of the possible tachycardia. High-dose opioid anesthesia causes minimal cardiovascular side effects along with bradycardia and thus may be useful in these patients. Preoperative β-blocker and calcium channel blocker therapy should be continued. Intravenous (IV) propranolol, esmolol, or verapamil may be administered intraoperatively to improve hemodynamic performance. Table 2-2 summarizes the anesthetic and circulatory management of obstructive HCM.

Anesthesia for management of labor and delivery in the parturient with obstructive HCM is quite complex. “Bearing down” (Valsalva maneuver) during delivery may worsen LVOT obstruction. Beta-blocker therapy may have been discontinued during pregnancy because of the association with fetal bradycardia and intrauterine growth retardation. Oxytocin must be used carefully because of its vasodilating properties and compensatory tachycardia. Pulmonary edema has been observed in parturients with HCM, emphasizing the need for careful fluid management. Spinal anesthesia is relatively contraindicated because of the associated vasodilation, but epidural anesthesia has been used successfully. General anesthesia is preferred by many practitioners. If hypotension occurs during anesthesia, the use of beta-agonists such as ephedrine may result in worsening outflow tract obstruction, and alpha-agonists such as phenylephrine, once thought to result in uterine vasoconstriction, are now preferred. However, careful titration of anesthetic agents and adequate volume loading (most often guided by invasive monitoring) is essential to safely conducted anesthesia in this clinical setting.

Anesthetic considerations

The main therapeutic options are similar to those for other arrhythmia-prone or heart failure patients. Patients often present with AICDs, and antiarrhythmic agents such as β-blockers or amiodarone may be helpful should arrhythmias occur. Catheter ablation of diseased areas of myocardium (acting as arrhythmogenic foci) can be useful in cases of refractory medical therapy. Cardiac transplantation is also an option as a final alternative.

As a rarer heart disease, minimal evidence exists for the optimal anesthetic management of patients with ARVC/D. It is one of the main causes of sudden, unexpected perioperative death, which can occur in low-risk surgical candidates, even in patients with a history of successful anesthesia. The uncommon nature of the disease makes it difficult to make specific recommendations for anesthetic management. If the condition is known, invasive continuous arterial BP monitoring is prudent intraoperatively. A PAC should probably be avoided, given the tendency toward arrhythmias. Propofol and etomidate appear to be safe induction agents. Neuromuscular blocking agents such as vecuronium, cisatracurium, and rocuronium are probably safe as well. AICDs should be managed according to the guidelines published and referred to throughout this text, regardless of the presence of ARVC/D.

Anesthetic considerations

Anesthetic management in patients with LV noncompaction depends on the severity of ventricular dysfunction, which should be evaluated preoperatively. In patients with impaired cardiac function, management should be directed toward preserving contractility and baseline levels of preload and afterload. Up to 80% of patients with LV noncompaction have a neuromuscular disorder, such as Duchenne’s or Becker’s muscular dystrophy or myotonic dystrophy. Thus, depolarizing neuromuscular junction blockers should be avoided or used with caution. Patients may be receiving anticoagulation for thromboembolic prophylaxis and may therefore have contraindications for using neuraxial techniques. AICDs are often inserted for indications such as arrhythmias or heart failure, and patients should be managed accordingly.

Data are limited regarding anesthetic management in patients with LV noncompaction syndrome. In a retrospective study on 60 patients with noncompaction undergoing 220 procedures, only patients undergoing general anesthesia experienced complications, compared to regional anesthesia or sedation/analgesia. Because the nature of the surgery often dictates the need for general anesthesia, patients with noncompaction syndrome requiring general anesthetics warrant vigilant monitoring in the perioperative period.

Lenègre’s disease

Progressive cardiac conduction defect, also known as Lenègre’s disease, has an autosomal dominant pattern of inheritance resulting in ion channelopathies, which manifest as conduction abnormalities. Lenègre’s disease involves primary progressive development of cardiac conduction defects in the His-Purkinje system. This leads to widening QRS complexes, long pauses, and bradycardia.

Wolff-parkinson-white syndrome

Wolff-Parkinson-White (WPW) is a rare pre-excitation syndrome that presents often as paroxysmal supraventricular tachycardia episodes. The presence of accessory anatomic bypass tracts enables the atrial impulse to activate the His bundle more rapidly than through the normal atrioventricular (A-V) nodal pathway. If the refractoriness in one of the pathways increases, a re-entrant tachycardia can be initiated. The electrocardiogram (ECG) in WPW syndrome demonstrates a short PR interval (< 0.12 msec), a delta wave (slurred transition between PR interval and R-wave upstroke), and a widened QRS complex. The incidence of sudden cardiac death in patients with WPW syndrome is estimated at 0.15% to 0.39% over 3 to 10 years of follow-up, and in WPW patients with a history of cardiac arrest, it is the presenting symptom in approximately 50%.

Medications that produce more refractoriness in one of the pathways can create a window of functional unidirectional block. This initiates a circle of electrical impulse propagation that results in a rapid ventricular rate. These patients are usually treated with drugs that increase the refractory period of the accessory pathway, such as procainamide, propafenone, flecainide, disopyramide, ibutilide, and amiodarone. However, individual patient response will vary depending on the window of unidirectional block, as well as the different effects the same drug has on both pathways. For example, verapamil and digoxin may perpetuate the arrhythmias, especially when WPW syndrome is associated with atrial fibrillation. A nonpharmacologic approach in the treatment of patients with pre-excitation syndromes is catheter ablation of the accessory pathways, with initial success of approximately 95% in most series.

Anesthetic considerations

The current treatment of choice for WPW is ablation of the accessory pathway, which is usually performed in electrophysiology laboratories. The procedures often involve periods of programmed electrical stimulation in attempts to provoke the arrhythmias before and after the ablation of the accessory pathway. Antiarrhythmic medications are usually discontinued before the procedure. Thus, these patients present for an anesthetic in a relatively unprotected state. Premedication is indicated to prevent anxiety, which could increase catecholamine levels and precipitate arrhythmias. Electrocardiographic (ECG) monitoring should be optimal for the diagnosis of atrial arrhythmias (leads II and V1).

If arrhythmias occur in WPW patients, A-V nodal blocking agents such as adenosine, β-blockers, diltiazem, and verapamil, as well as lidocaine, should be used with caution. These A-V blockers must be avoided if atrial fibrillation is suspected, because these drugs can promote conductance through the accessory pathway with rapid ventricular response. Digoxin is contraindicated in WPW patients. Amiodarone, sotalol, ibutilide, flecainide, or procainamide is preferable in such cases.

If general anesthesia is needed, it is reported that opioid-benzodiazepine or opioid-propofol anesthetic regimens show no effect on electrophysiologic parameters of the accessory conduction pathways. Volatile anesthetics theoretically increase refractoriness within the accessory and A-V pathways; however, modern volatile anesthetic agents are widely used in patients undergoing ablation procedures under general anesthesia. Dexmedetomidine is frequently used for radiofrequency ablation procedures performed under sedation, because it is unlikely to exacerbate tachycardias and more likely to cause bradycardia.

Long QT syndrome

Long QT syndrome, the most common of the ion channelopathies, is characterized by prolongation of ventricular repolarization and the QT interval (QTc > 440 msec). It increases the risk of developing polymorphic ventricular tachycardia (torsade des pointes). This can lead to syncope and sudden cardiac death. The more common pattern of inheritance is autosomal dominant, referred to as Romano-Ward syndrome. The rare, autosomal recessive inheritance pattern is associated with deafness, called Jervell and Lange-Nielsen syndrome. In untreated patients, mortality approaches 5% per year, quite remarkable for a population with median age in the 20s. The severity of the disease is judged by the frequency of syncopal attacks. These attacks may be caused by ventricular arrhythmias or sinus node dysfunction. The development of torsade de pointes is especially ominous and may be the terminal event for these patients.

Torsade de pointes is a malignant variety of ventricular tachycardia with a rotating QRS axis that is resistant to cardioversion. The pathogenesis of this syndrome is theorized to be an imbalance of sympathetic innervation. Left stellate ganglion stimulation lowers the threshold for ventricular arrhythmias, while right stellate ganglion stimulation is protective against ventricular arrhythmias. Patients receiving β-blockers and those with high left thoracic sympathectomy had relief of syncope and decreased mortality.

Brugada’s syndrome

Patients with Brugada’s syndrome have characteristic ECG findings of right bundle branch block and ST-segment elevation in the anterior precordial leads (V ₁ -V ₃ ). It is inherited in an autosomal dominant pattern. Brugada’s syndrome may present as sudden nocturnal death from ventricular fibrillation or tachycardia, especially in Southeast Asian males.

Catecholaminergic polymorphic ventricular tachycardia

Catecholaminergic polymorphic ventricular tachycardia (CPVT) has two patterns of inheritance that lead to ventricular tachycardia triggered by vigorous physical exertion or acute emotion, usually in children and adolescents. This can lead to syncope and sudden death. The resting ECG is unremarkable, with the exception of sinus bradycardia and prominent U waves in some cases. The most common arrhythmia seen in CPVT is a bidirectional ventricular tachycardia with an alternating QRS axis.

Short QT syndrome

Short QT syndrome is characterized by a short QT interval (QTc < 330 msec) and ECG appearance of tall, peaked T waves. It is associated with polymorphic ventricular tachycardia and ventricular fibrillation.

Idiopathic ventricular fibrillation

The literature describes a group of cardiomyopathies designated as idiopathic ventricular fibrillation. Data are insufficient, however, to establish this as a distinct cardiomyopathy. It is likely the summation of multiple etiologies that lead to arrhythmias, probably caused by ion channel mutations.

Anesthetic considerations

Patients with ion channelopathies may present intraoperatively or in the postanesthesia care unit with sudden arrhythmias that warrant vigilant ECG monitoring. Continuous invasive intra-arterial BP monitoring should be considered in patients with a history of frequent arrhythmias. Patients should be treated as any patient prone to arrhythmias; this includes avoiding arrhythmogenic medications and immediate availability of a cardioverter-defibrillator device. Few data are available on anesthetic recommendations for these cardiomyopathies. Patients with long QT syndrome will occasionally present for high left thoracic sympathectomy and left stellate ganglionectomy, although most patients with these ion channelopathies will most likely present for surgery unrelated to their primary disorder.

Patients with long QT syndrome seem to be at increased risk of arrhythmia during periods of enhanced sympathetic activity, particularly during emergence from general anesthesia with use of potent volatile agents, and when neuromuscular blocker reversal drugs were given with ondansetron in children. Beta blockade has been described as the most successful medical management of patients with congenital long QT syndrome types I and II, which affect potassium channels. Beta blockade is contraindicated in type III, which involves sodium channels. In patients who receive β-blockers, it is reasonable to continue beta blockade perioperatively. Intraoperatively and particularly during long procedures, supplemental IV doses of a β-blocker or a continuous infusion of esmolol should be considered.

The anesthetic technique should be tailored to minimize sympathetic stimulation. A balanced anesthetic technique with adequate opioid administration is appropriate for this purpose, and is effective at suppressing catecholamine elevations in response to stimuli. Nitrous oxide (N ₂ O) causes mild sympathetic stimulation and thus should be avoided. Medications that can further prolong the QT interval should probably be avoided, including isoflurane, sevoflurane, thiopental, succinylcholine, neostigmine, atropine, glycopyrrolate, metoclopramide, 5HT3 receptor antagonists, and droperidol. Ketamine is generally not recommended as an induction agent in patients with congenital long QT syndrome. Despite the QT-prolonging effect, thiopental has been used without adverse consequences. Propofol has no effect on or may actually shorten the QT interval and is theoretically a good choice of induction agent. Anxiolysis with midazolam has been used successfully.

In patients with Brugada’s syndrome, sodium channel blockers such as procainamide and flecainide are contraindicated, and medications such as neostigmine, class 1A antiarrhythmic drugs, and selective α-adrenoreceptor agonists may increase ST segment elevation and should also be avoided. Thiopental, isoflurane, sevoflurane, N ₂ O, morphine, fentanyl, ketamine, and succinylcholine have been used successfully. Some report arrhythmias related to propofol administration. In contrast to patients with long QT syndrome, propofol should be used with caution in patients with Brugada’s syndrome.

Inflammatory cardiomyopathy (myocarditis)

There are a wide variety of toxins and drugs that cause inflammatory myocarditis ( Table 2-3 ). Infectious myocarditis typically evolves through several stages of active infection, through healing, and may ultimately culminate in DCM.

Myocarditis presents with the clinical picture of fatigue, dyspnea, and palpitations, usually in the first weeks of the infection, progressing to overt congestive heart failure (CHF) with cardiac dilation, tachycardia, pulsus alternans, and pulmonary edema. Between 10% and 33% of patients with infectious heart diseases will have ECG evidence of myocardial involvement. Mural thrombi often form in the ventricular cavity and may result in systemic or pulmonary emboli. Supraventricular and ventricular arrhythmias are common. Fortunately, patients usually have complete recovery from infectious myocarditis, although exceptions include myocarditis associated with diphtheria or Chagas’ disease. Occasionally, acute myocarditis may even progress to a recurrent or chronic form of myocarditis, resulting ultimately in a restrictive type of cardiomyopathy caused by fibrous replacement of the myocardium.

In the bacterial varieties of myocarditis, isolated ECG changes or pericarditis are common and usually benign, whereas CHF is unusual. Diphtheritic myocarditis is generally the worst form of bacterial myocardial involvement; in addition to inflammatory changes, its endotoxin is a competitive analog of cytochrome B and can produce severe myocardial dysfunction. The conduction system is especially affected in diphtheria, producing either right or left bundle branch block, which is associated with 50% mortality. When complete heart block supervenes, mortality approaches 80% to 100%. Syphilis, leptospirosis, and Lyme disease represent three examples of myocardial infection by spirochetes. Tertiary syphilis is associated with multiple problems, including arrhythmias, conduction disturbances, and CHF. Lyme disease myocarditis usually presents with conduction abnormalities, such as bradycardia and A-V nodal block.

Viral infections manifest primarily with ECG abnormalities, including PR prolongation, QT prolongation, ST-segment and T-wave abnormalities, and arrhythmias. However, each viral disease produces slightly different ECG changes, with complete heart block being the most significant. Most of the viral diseases have the potential to progress to CHF if the viral infection is severe. Recent advances in molecular biologic techniques have allowed for more accurate identification of viruses. Previously, coxsackievirus B was the most common virus identified as producing severe viral heart disease. Currently, the most prevalent viral genomes detected are enterovirus, adenovirus, and parvovirus B19. Although the pathogenic role of enterovirus in myocarditis and chronic DCM is well established, whether parvovirus B19 is incidental or pathogenic in viral myocarditis is still unclear. Epstein-Barr virus (EBV) and human herpesvirus 6 (HHV-6) have also been implicated in viral myocarditis. The presence of parvovirus B19, EBV, and HHV-6 is associated with a decline in cardiac function within 6 months.

Subsequently, there may be an autoimmune phase in which the degree of the cardiac inflammatory response correlates with a worse prognosis, which may culminate in DCM. The 2009 H1N1 pandemic influenza strain was associated with myocarditis as well. In one study, patients with H1N1 influenza associated with myocarditis were predominantly female, young (mean age 33.2 years), and had morbidity/mortality of 27%.

Mycotic myocarditis has protean manifestations that depend on the extent of mycotic infiltration of the myocardium and may present as CHF, pericarditis, ECG abnormalities, or valvular obstruction.

Of the protozoal forms of myocarditis, Chagas’ disease, or trypanosomiasis, is the most significant, and the most common cause of chronic CHF in South America. ECG changes of right bundle branch block and arrhythmias occur in 80% of patients. In addition to the typical inflammatory changes in the myocardium that produce chronic CHF, a direct neurotoxin from the infecting organism, Trypanosoma cruzi, produces degeneration of the conduction system, often causing severe ventricular arrhythmias and heart block with syncope. The onset of atrial fibrillation in these patients is often an ominous prognostic sign.

Helminthic myocardial involvement may produce CHF, but more frequently symptoms are secondary to infestation and obstruction of the coronary or pulmonary arteries by egg, larval, or adult forms of the worm. Trichinosis, for example, produces a myocarditis secondary to an inflammatory response to larvae in the myocardium, even though the larvae themselves disappear from the myocardium after the second week of infestation.

Noninflammatory dilated cardiomyopathy

The noninflammatory variety of dilated cardiomyopathy also presents as myocardial failure, but in this case caused by idiopathic, toxic, degenerative, or infiltrative processes in the myocardium ( Table 2-4 ).

As an example of the toxic cardiomyopathy type, alcoholic cardiomyopathy is a typical hypokinetic noninflammatory cardiomyopathy associated with tachycardia and premature ventricular contractions that progress to left ventricular failure with incompetent mitral and tricuspid valves. This cardiomyopathy probably results from a direct toxic effect of ethanol or its metabolite acetaldehyde, which releases and depletes cardiac norepinephrine. Alcohol may also affect excitation-contraction coupling at the subcellular level. In chronic alcoholic patients, acute ingestion of ethanol produces decreases in contractility, elevations in ventricular end-diastolic pressure, increases in SVR and systemic hypertension.

Alcoholic cardiomyopathy is classified into three hemodynamic stages. In stage I, cardiac output, ventricular pressures, and left ventricular end-diastolic volume (LVEDV) are normal, but the ejection fraction (EF) is decreased. In stage II, cardiac output is normal, although filling pressures and LVEDV are increased, and EF is decreased. In stage III, cardiac output is decreased, filling pressures and LVEDV are increased, and EF is severely depressed. Most noninflammatory forms of DCM undergo a similar progression.

Doxorubicin (Adriamycin) is an antibiotic with broad-spectrum antineoplastic activities. Its clinical effectiveness, however, is limited by its cardiotoxicity. Doxorubicin produces dose-related DCM. Doxorubicin may disrupt myocardial mitochondrial calcium homeostasis. Patients treated with this drug must undergo serial evaluations of left ventricular systolic function. Dexrazoxane, a free-radical scavenger, may protect the heart from doxorubicin-associated damage.

Pathophysiology

The key hemodynamic features of the DCMs are elevated filling pressures, failure of myocardial contractile strength, and a marked inverse relationship between afterload and stroke volume. Both the inherited and the nonfamilial forms of inflammatory and noninflammatory DCMs present a picture identical to that of CHF produced by severe coronary artery disease (CAD). In some conditions the process that has produced the cardiomyopathy also involves the coronary arteries. The pathophysiologic considerations are familiar. As the ventricular muscle weakens, the ventricle dilates to take advantage of the increased force of contraction that results from increasing myocardial fiber length. As the ventricular radius increases, however, ventricular wall tension rises, increasing both the oxygen consumption of the myocardium and the total internal work of the muscle. As the myocardium deteriorates further, the cardiac output falls, with a compensatory increase in sympathetic activity to maintain organ perfusion and cardiac output. One feature of the failing myocardium is the loss of its ability to maintain stroke volume in the face of increased afterload. Figure 2-2 shows that in the failing ventricle, stroke volume falls almost linearly with increases in afterload. The increased sympathetic outflow that accompanies left ventricular failure initiates a vicious cycle of increased resistance to forward flow, decreased stroke volume and cardiac output, and further sympathetic stimulation in an effort to maintain circulatory homeostasis.

Stroke volume (SV) as a function of afterload for normal left ventricle, for left ventricle with moderate dysfunction, and for failing left ventricle.

Mitral regurgitation is common in severe DCM due to stretching of the mitral annulus (Carpentier Type I) and distortion of the geometry of the chordae tendineae, resulting in restriction of leaflet apposition (Carpentier Type IIIb). The forward stroke volume improves with afterload reduction, even with no increase in EF. This suggests that reduction of mitral regurgitation is the mechanism of the improvement. Afterload reduction also decreases left ventricular filling pressure, which relieves pulmonary congestion and should preserve coronary perfusion pressure.

The clinical picture of the DCM falls into the two familiar categories of forward and backward failure. The features of “forward” failure, such as fatigue, hypotension, and oliguria, are caused by decreases in cardiac output with reduced organ perfusion. Reduced perfusion of the kidneys results in activation of the renin-angiotensin-aldosterone system, which increases the effective circulating blood volume through sodium and water retention. “Backward” failure is related to the elevated filling pressures required by the failing ventricles. As the left ventricle dilates, end-diastolic pressure rises, and mitral regurgitation worsens. The manifestations of left-sided failure include orthopnea, paroxysmal nocturnal dyspnea, and pulmonary edema. The manifestations of right-sided failure include hepatomegaly, jugular venous distention, and peripheral edema.

Anesthetic considerations

Electrocardiographic monitoring is essential in the management of patients with DCMs, particularly in those with myocarditis. Ventricular arrhythmias are common, and complete heart block, which can occur from these conditions, requires rapid diagnosis and treatment. The ECG is also useful in monitoring ischemic changes when CAD is associated with the cardiomyopathy, as in amyloidosis.

Direct invasive intra-arterial BP monitoring during surgery provides continuous information and a convenient route for obtaining arterial blood gases (ABGs). Any DCM patient with a severely compromised myocardium who requires anesthesia and surgery should have central venous access for monitoring and vasoactive drug administration. The use of a PAC is much more controversial. The American Society of Anesthesiologists (ASA) Task Force on Pulmonary Artery Catheterization has published practice guidelines. The indication for PAC placement depends on a combination of patient-, surgery-, and practice setting–related factors. Patients with severely decreased cardiac function from DCM have significant cardiovascular disease and are considered at increased or high risk. With no evidenced-based medicine to support outcome differences, recommendations for PAC monitoring were based on expert opinion at that time. Patients with DCM presenting for surgery who have an overall increased or high-risk score should probably have hemodynamic parameters monitored with a PAC. In addition to measuring right- and left-sided filling pressures, a thermodilution PAC may be used to obtain cardiac output and calculate SVR and pulmonary vascular resistance (PVR), which allow for serial evaluation of the patient’s hemodynamic status. PACs with fiberoptic oximetry, rapid-response thermistor catheters that calculate right ventricular EF, and pacing PAC are available. Pacing PAC and external pacemakers provide distinct advantages in managing the patient with myocarditis and associated heart block. Recent evidence seems to provide further support for clinicians who choose not to use PAC monitoring on the basis of no outcome differences between high-risk surgical patients who were cared for with and without PAC monitoring and goal-directed therapy.

Transesophageal echocardiography provides useful data on ventricular filling, ventricular function, severity of mitral regurgitation, and response of the impaired ventricle to anesthetic and surgical manipulations. Recent guidelines indicate that hemodynamic decompensation is a class I indication for TEE monitoring. With the increased availability of equipment and trained anesthesiologists, TEE will become increasingly important in the perioperative management of patients with cardiomyopathies.

The avoidance of myocardial depression still remains the goal of anesthetic management for patients with DCM, although, paradoxically, beta-adrenergic blockade has been associated with improved hemodynamics and improved survival in patients with DCM. (This may result from an antiarrhythmic effect.) All the potent volatile anesthetic agents are myocardial depressants, and therefore high concentrations of these agents are probably best avoided in these patients. Low doses are usually well tolerated, however, and frequently used as part of a balanced anesthetic.

For the patient with severely compromised myocardial function, the synthetic piperidine narcotics (fentanyl, sufentanil, remifentanil) are useful because myocardial contractility is not depressed. Bradycardia associated with high-dose narcotic anesthesia may be prevented by the use of pancuronium for muscle relaxation, anticholinergic drugs, or pacing. Pancuronium, however, should be avoided in patients with impaired renal function, a common problem in cardiomyopathy patients. For peripheral or lower abdominal surgical procedures, a regional anesthetic technique is a reasonable alternative, provided filling pressures are carefully controlled and the hemodynamic effects of the anesthetic are monitored. A recent study suggests that thoracic epidural used as a therapeutic strategy in addition to medical therapy in patients with DCM may improve cardiac function and reduce hospital readmission and mortality. One problem is that regional anesthesia is frequently contraindicated because patients with cardiomyopathies are frequently treated with anticoagulant and antiplatelet drugs to prevent embolization of mural thrombi that develop on hypokinetic ventricular wall segments.

In planning anesthetic management for the patient with DCM, associated cardiovascular conditions, such as the presence of CAD, valvular abnormalities, LVOT obstruction, and constrictive pericarditis should also be considered. Patients with CHF often require circulatory support intraoperatively and postoperatively. Inotropic drugs such as dopamine and dobutamine are effective in low output states and produce modest changes in SVR at lower dosages. In severe ventricular failure, more potent drugs such as epinephrine may be required. Phosphodiesterase-III inhibitors, such as milrinone, with inotropic and vasodilating properties, may improve hemodynamic performance. As previously noted, stroke volume is inversely related to afterload in the failing ventricle, and reduction of left ventricular afterload with vasodilating drugs such as nicardipine, nitroprusside, and nesiritide are also effective in increasing cardiac output.

In patients with myocarditis, especially of the viral variety, transvenous or external pacing may be required should heart block occur. Intra-aortic balloon counterpulsation, left ventricular assist devices, and cardiac transplantation are further options to be considered in the case of the severely compromised ventricle. Incidence of supraventricular and ventricular arrhythmias increases in myocarditis and DCM. These arrhythmias often require extensive electrophysiologic workup and may be unresponsive to maximal medical therapy. Frequently, patients with DCM present for AICD implantation or ventricular arrhythmia ablation procedures.

Anesthetic considerations

Anesthetic and monitoring considerations in patients with restrictive cardiomyopathies are similar to those of constrictive pericarditis and cardiac tamponade, with the additional feature of poor ventricular function in later stages of the disease. (See Constrictive Pericarditis later for the physiology and management of restrictive ventricular filling and earlier Dilated Cardiomyopathy for the management of impaired ventricular function.) Anesthetic management depends on whether restrictive physiology or heart failure is predominant.

Despite normal ventricular function, diastolic dysfunction in patients with restrictive cardiomyopathy leads to a low cardiac output state. Monitoring should include at a minimum invasive intra-arterial BP monitoring, and central venous access should be established in patients with advanced disease. A PAC offers the advantage of cardiac output measurement and the assessment of loading conditions, both of which may be helpful in guiding anesthetic management, even though outcome data has not been established for this particular group of patients.

When inducing anesthesia, it may be prudent to avoid medications that produce bradycardia, decreased venous return, and myocardial depression. Etomidate can be used for anesthesia induction with little impact on hemodynamics and myocardial function. Ketamine, even though intrinsic cardiodepressive properties have been described, maintains SVR and is frequently used in these patients. Anesthesia can typically be maintained with a balanced anesthesia technique using lower doses of inhaled potent volatile anesthetics, supplemented with an opioid such as fentanyl or sufentanil. A high-dose opioid technique, as recommended in the past, is usually reserved for patients with advanced disease who may not tolerate inhalational anesthetic agents.

Anesthetic considerations

General anesthesia is considered safe in HIV/AIDS patients, but drug interactions and their impact on various organ systems and the patient’s overall physical status should be considered preoperatively. Rarely, patients with advanced disease may also have pericardial involvement with pericardial effusion and tamponade. An echocardiographic evaluation may provide useful information in this setting. A preoperative chest radiograph should be available in all symptomatic patients undergoing surgery under general anesthesia to rule out tuberculosis and acute pulmonary infections. Although general anesthesia may suppress the immune system, no adverse effects on patients with HIV/AIDS have been found. Regional anesthesia is often the technique of choice, and early concerns regarding neuraxial anesthesia and the potential spread of infectious material intrathecally could not be confirmed.

Drug interactions between antiviral medications and drugs used during anesthesia induction and maintenance have been described, but serious side effects are rare. Antiviral medications should be continued perioperatively in patients scheduled for surgery.

Stress (Takotsubo) Cardiomyopathy

Stress cardiomyopathy is a relatively recently described clinical entity, also known by its Japanese name, Takotsubo, (“octopus trap”). It is typically characterized by reversible apical left ventricular systolic dysfunction in the absence of atherosclerotic CAD that is triggered by profound psychological stress. Although traditionally the disease is described as “apical ballooning” (resembling an octopus trap), Takotsubo cardiomyopathy may manifest as midventricular and basal ventricular dysfunction. The ventricular pathology overall is the result of myocardial stunning, leading to transient periods of ischemia, possibly from coronary artery vasospasm. Other proposed mechanisms include catecholamine-induced damage, microvascular endothelial dysfunction, and neurogenically mediated myocardial stunning. On ECG, this disease mimics ST-elevation myocardial infarction.

Treatment includes providing mechanical ventilatory support, vasopressors to support systemic blood pressure, and diuretics as needed. Fortunately, stress cardiomyopathy is usually transient and resolves with supportive care.

There is no current consensus on how to best deliver anesthesia to patients with a history of Takotsubo cardiomyopathy. Most case reports describe that adverse events occurred mostly during general anesthesia, and surgery performed under regional anesthesia was well tolerated. Such reports are so few, however, that recommendations on anesthesia technique cannot be made at this time. It seems prudent to make attempts to prevent emotional stress or sympathetic surges, which frequently occur in the perioperative period. Adequate sedation and anxiolysis should therefore be provided preoperatively.

Peripartum cardiomyopathy

Peripartum cardiomyopathy typically develops during the third trimester of pregnancy or within 5 months after delivery. It is a distinct form of cardiomyopathy and unrelated to any other cause of heart failure. Symptoms are those of systolic heart failure, including sudden cardiac arrest, and develop in the majority of patients within 4 months after delivery. Perioperative cardiomyopathy (HCM) carries a significant risk for high morbidity and mortality, but full recovery is possible. Treatment and anesthetic management of patients with peripartum cardiomyopathy depend on the severity of presenting symptoms. The most common form of clinical presentation for anesthesiologists is significantly decreased systolic cardiac function, including cardiogenic shock, and should be treated accordingly. The underlying pathophysiology is similar to that of a dilated cardiomyopathy, as discussed earlier.