Progress in Cardiovascular Diseases 54 (2012) 503–511www.onlinepcd.com

Anesthesia Management of Patients with HypertrophicObstructive Cardiomyopathy

Michal Gajewski, Zak Hillel⁎

St Luke's–Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York, NY

Abstract Hypertrophic obstructive cardiomyopathy presents a challenge to the anesthesiologist. Because

Statement of Confl⁎ Address reprint

St Luke's–Roosevelt HNY 10025.

E-mail address: zh

0033-0620/$ – see frodoi:10.1016/j.pcad.20

the condition is relatively prevalent, it is important for anesthesiologist to be aware of thepathophysiology. In this review, we draw upon case reports and studies of the anesthesiamanagement of patients with hypertrophic obstructive cardiomyopathy to enhance medicaldecision making. The scope of this article ranges from the preoperative period, when theseverity of the obstruction needs to be assessed; the intraoperative period, with monitoring, aswell as general management guidelines; and finally, the postoperative period, when it isimportant to minimize the sympathetic response. Furthermore, we address the management ofthe obstetric patient, with particular focus on neuraxial anesthesia, and extrapolate how this typeof anesthesia may be applied to the management of patients undergoing nonlaboring,noncardiac surgery. (Prog Cardiovasc Dis 2012;54:503-511)

© 2012 Elsevier Inc. All rights reserved.

Keywords: Obstructive hypertrophic cardiomyopathy; Hypertrophic cardiomyopathy; Anesthetic management

Since the first documented case of subaortic stenosisand asymmetric myocardial hypertrophy by Brock1 in1957 and Teare2 in 1958, there have been significantadvances in the understanding of the pathophysiology andin the management of hypertrophic obstructive cardiomy-opathy (HOCM). It is not uncommon for these patients tonow have normal lifespans.3 This means that sooner orlater, most anesthesiologists will encounter HOCM, notonly during a therapeutic surgical septal myectomy butalso for many routine, noncardiac cases. Because two-thirds 3 of patients have left ventricular (LV) obstructioneither at rest or after physiologic provocation,4 theanesthesiologist must be capable of managing this uniquecondition. The purposes of this article are to review the

ict of Interest: see page 509.requests to Zak Hillel, PhD, MD, Anesthesiology,ospital Center, 1111 Amsterdam Ave, New York,

2@columbia.edu (Z. Hillel).

nt matter © 2012 Elsevier Inc. All rights reserved.12.04.002

current literature and to provide evidence-based recom-mendations for patients with HOCM.

Definition

As established by Maron and Epstein5 in 1979,hypertrophic cardiomyopathy (HCM), or HOCM whenobstruction is present, is the preferred nomenclature forthis disease. Part of the confusion with HOCM pertains tothe differentiation of obstructive vs nonobstructivepathophysiology because HCM, in the resting patient, ismostly nonobstructive6 and that physiologic changes inpreload, afterload, and contractility may alter or evenproduce de novo LV outflow tract (LVOT) obstruction.7

Prevalence, pathophysiology, and prognosis

Initially believed to be relatively rare, it is now knownthat HCM occurs in about 2 of 1000 patients, potentiallyaffecting close to 600 000 people in the United States.8-10

503

Abbreviations and Acronyms

CVP = central venouspressure

HCM = hypertrophiccardiomyopathy

HOCM = hypertrophicobstructive cardiomyopathy

LVOT = left ventricularoutflow tract

PCPW = Pulmonary capillarywedge pressure

SAM = systolic anteriormotion

TEE = transesophagealechocardiography

504 M. Gajewski, Z. Hillel / Progress in Cardiovascular Diseases 54 (2012) 503–511

Many cases manifestduring adolescence11;however, late-onset car-diomyopathy may de-velop at any age, andlong-term survival maybe affected by the timeof presentation, withthose identified in chil-dren showing a de-creased survival as compared with those identi-fied in adulthood.3

Hypertrophic cardio-myopathy is described asa heterogenous autoso-mal dominant disease ofthe myocardial sarco-

mere that may involve 1000 different mutations in 18different proteins.3,4 Microscopically, HCM is character-ized by myocardial disarray.12 Sarcomeric protein muta-tions may cause abnormal activation of myocyte growthpatterns, which then lead to uncoordinated muscle functionand eventual hypertrophy.12,13 Obstructive HCM may besubaortic, or midventricular, or both.14,15 These charac-teristics will determine the degree of obstruction, subse-quent symptoms, alterations in hemodynamics, and theincidence of arrhythmias—all of which have implicationsfor anesthetic management. Subaortic obstruction is causedby systolic anterior motion (SAM) of the anterior mitralleaflet. There is now consensus that drag, the pushing forceof flow, is the dominant hydrodynamic force on the mitralvalve that causes SAM.4,15,16 This causes the mitral leafletto make contact with the ventricular septum causingobstruction, with concomitant mitral regurgitation due todeformation of leaflet position.4 The mitral valve mayundergo distortion and thickening due to hemodynamic orin situ abnormalities, predisposing it to endocarditis and,very rarely, rupture of the chordae tendinae.14 Withmidventricular pathology, the obstruction occurs at thepapillary muscle level10,15 due to systolic apposition LVwall or due to a hypertrophied anomalous papillarymuscle.17,18 Unlike subaortic obstruction, with midven-tricular obstruction, mitral regurgitation is often absent.10

As described elsewhere, the peak instantaneous LVoutflow gradient, rather than the mean gradient, guidestreatment, and therefore, all therapeutic suggestions willfocus on the peak gradient. There are 3 categories ofdynamic LV outflow tract obstruction. There is restingobstruction with gradients of 30 mm Hg or greater at rest;latent obstruction without gradients at rest, but gradientsgreater than 30 mm Hg with physiologic provocation; andprovocable obstruction with mild, less than 30 mm Hggradients at rest, but high gradients after provocativemaneuvers.4 Obstructed patients either at rest or withphysiologic provocation (exercise) are two-thirds of

patients.4,19 It is important to differentiate the obstructiveand nonobstructive forms of the disease because thisdistinction guides anesthetic considerations. Patients withobstructive cardiomyopathy generally tend to be moresymptomatic and prone to perioperative decompensation.

In addition to LVOT obstruction and mitral regurgita-tion, the pathophysiology of HCM also may includediastolic dysfunction, myocardial ischemia, and arrhyth-mias, all of which can have adverse implications duringanesthesia and surgery. Indeed, diastolic dysfunctionoftentimes may be the reason for decompensation whennonobstructive HCM is present. This is due to slowrelaxation and elevated end-diastolic pressures, which canmimic a picture of left and (infrequently) right-sided heartfailure with dyspnea and chest pain.9,15 Myocardialischemia may occur at any time in patients with HCMbecause there is a mismatch of oxygen supply and demanddue to the hypertrophied muscle.20 There is also a degreeof microvascular dysfunction in patients with HCM,which may, on its own, be a predictor of clinicaldecompensation and death.21 Lastly, although manydifferent arrhythmias may occur in patients with HCM,atrial fibrillation is the most common sustained arrhyth-mia, occurring in 20% to 25% of patients.10 Atrialfibrillation is also associated with mortality due to heartfailure and stroke.3,10,22 Thus, patients with HCM andatrial fibrillation should be anticoagulated with warfarin ordabigatran, unless there is a contraindication.4,22

Left ventricular outflow tract obstruction not onlydefines the hemodynamics of HCM, but is also anindependent determinant of heart failure and cardiovascu-lar death.23 In a 2003 study, Maron et al24 found thatpatients with LVOT obstruction (defined as a basalgradient of at least 30 mm Hg) had an increased risk ofdeath from HCM or progression to congestive heartfailure, which was more than 4 times that of patientswithout obstruction. In the same study, it was found thatpatients with obstruction, particularly if older than 40years, have a higher probability of progression to NewYork Heart Association class III or IV heart failure anddeath.24 Patients with HOCM have an annual mortalityrate of 1.3% (of which 0.7% is attributable to suddencardiac death) and a higher rate of morbidity than theirhealthy peers.

Diagnosis

Because surgery and anesthesia have the potential toincrease the myocardial workload and decrease preload,patients with HCM are at risk for increased LVOTobstruction and arrhythmic complications. It is, thus,prudent to routinely follow guidelines set forth inAssessing and Reducing the Cardiac Risk of NoncardiacSurgery and the American College of Cardiology/Amer-ican Heart Association 2007 guidelines on perioperative

505M. Gajewski, Z. Hillel / Progress in Cardiovascular Diseases 54 (2012) 503–511

cardiovascular evaluation and care for noncardiacsurgery.25,26 Electrocardiography is recommended in allpatients suspected of having HCM as part of the initialevaluation.4 Indeed, more than 85% of patients withHOCM will have an abnormal result of electrocardio-graphy.27-29 Lastly, as discussed earlier, supraventriculararrhythmias are common in patients with LVOT obstruc-tion and should be identified preoperatively.

Echocardiography is the standard for the diagnosis ofHCM. Transthoracic echocardiography will determine theextent of the hypertrophy, whether there is systolic ordiastolic dysfunction, the degree of obstruction, and thepresence of any independent valvular lesions. In adults,HCM is diagnosed when LV wall thickness is more than15 mm in the absence of any condition that mightotherwise cause such a degree of LV hypertrophy. Amongchildren, the criteria for the diagnosis of HCM aregenerally accepted as a diastolic wall thickness greaterthan 2 SDs (generally, 1.5 cm) from the mean corrected forage, sex, and height.5,29 Further diagnostic examinationssuch as magnetic resonance imaging may be considered ifthe diagnosis is in question or if the location ofhypertrophy is difficult to determine or quantify. Magneticresonance imaging detection of areas of delayed hyper-enhancement after gadolinium indicates fibrosis.30

Cardiac catheterization with coronary angiographyhas been recommended for patients having anginalsymptoms or those who have an intermediate to highlikelihood of developing coronary artery disease. Stresstesting, on the other hand, is recommended to determinefunctional capacity and response to therapy. The lattercan also be used to assess the risk of sudden cardiacdeath.4 A study by Sharma et al31 found that a failure ofsystolic blood pressure to increase by 20 mm Hg fromrest to peak exercise, or a progressive decrease in bloodpressure during exercise, is a risk factor, albeit with lowpredictive accuracy, for sudden cardiac death. Further-more, the response to stress testing is more reliable thanthe New York Heart Association classification inassessing the functional status of patients.26 BecauseLVOT obstruction is a dynamic pathology, an exercisetest is a valuable way to determine the presence of alatent or provocable obstruction.32

Treatment

It is critical that preoperative optimization minimize thepotential for LVOT obstruction because obstruction is anindependent risk factor for congestive heart failure anddeath.15,25 Negative inotropes are the mainstay oftreatment because of their ability to reduce tachycardia,decrease the hydrodynamic (drag) forces on the mitralvalve, and increase diastolic filling time.4,19,33 Symptom-atic patients with LVOT obstruction gradients greater than30 mm Hg should receive pharmacologic therapy with

agents that are capable of reducing the basal gradient, suchas β-blockers, calcium channel blockers, and diso-pyramide.33-35 It may also be prudent to treat evenasymptomatic patients preoperatively with negative ino-tropes such as β-blockers, especially if other confoundingfactors are present. If patients cannot tolerate β-blockers orare unresponsive, verapamil has been advocated due to itsnegative chronotropic and inotropic effects.19 Cautionmust be exercised with the use of calcium channelblockers because a reduction in preload and afterloadmay exacerbate the outflow tract obstruction and precip-itate pulmonary edema.36 Disopyramide, a potent negativeinotrope, has also been shown to ameliorate symptoms ofobstruction and reduce the subaortic outflow gradient by50% during a 3-year period of therapy.35 Cibenzoline,another class Ia antiarrhythmic, also having potentnegative inotropic properties, was studied in 10 patientsand demonstrated short and long-term reduction of theLVOT pressure gradient. Unfortunately, it is not availablein the United States.37

Patients who fail maximum pharmacologic therapy andwho still have gradients greater than 50 mm Hg may betreated surgically.4,9,29,38-40 Septal myectomy permanent-ly abolishes SAM of the mitral valve and the potential formitral regurgitation. In addition, long-term survival aftermyectomy is similar to that of the general population.40

Additional modalities of invasive treatment are available,such as alcohol septal ablation.

Implantable cardioverter-defibrillator placement isrecommended for patients with HCM with prior docu-mented cardiac arrest, ventricular fibrillation, or hemody-namically significant ventricular tachycardia (termedsecondary prevention) and for patients who have riskfactors for sudden death.4 In addition, permanent rightventricular pacing with short atrioventricular delay may beconsidered in obstructed patients who are symptomaticand refractory to medical treatment and are not optimalcandidates for surgery or ablation.4

Preoperative considerations

To date, there are no official guidelines for theanesthetic management of patients with HOCM, and theliterature reflects cohort studies and case reports ofcomplicated patients. With HCM pathophysiology inmind, the primary goals of every anesthesiologist shouldbe to identify the patient with obstruction, stratify the riskfactors present, optimize cardiac function, and planappropriate management to minimize exacerbation oradverse outcomes.

The 1985 study of Thompson et al41 regardingperioperative anesthetic risk of noncardiac surgery inobstructive HCM was the first article published dealingspecifically with anesthesia and its effects on these patients.Although the conclusion was that these patients are

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generally at low risk when undergoing general anesthesiaand major noncardiac surgery, the study did identify anumber of complications such as hypotension, myocardialinfarction, arrhythmia, and angina.41 Since then, there havebeen a number of case reports relating to patientsundergoing noncardiac and cardiac surgery successfully.The key management principle is to identify those patientswith the greatest potential for obstruction, which can beaccomplished with a thorough interview, physical exam-ination, and the use of predictive diagnostic tests.

Because most HOCM cases are familial, it is prudentto elicit a thorough family history. Left ventricularoutflow tract obstruction, arrhythmias, and sudden deathrisk factors must be identified. It is imperative toquestion regarding the patient's functional status andexercise tolerance.

Most patients with HOCM have symptoms of dyspnea,angina, and syncope with exertion and the presence of amurmur.9 In contrast, the diagnosis of nonobstructiveHCM may be missed because of the relative paucity ofsymptoms and the absence of a murmur; thus, a high indexof suspicion must be maintained. Additional symptomsmay include angina, palpitations, syncope, peripheraledema, and orthopnea.42 In addition, the presence ofcongestive heart failure may confound the diagnosis ofHCM, particularly in patients with atrial fibrillation, severesystolic or diastolic dysfunction, and severe outflowobstruction.3,9,15 It is essential to assess functionalcapacity and reserve through careful questioning anddiagnostic tests. Most patients having a diagnosis of HCMwill have extensive knowledge of their disease and have acomplete cardiac workup before surgery. However, theanesthesiologist must be aware of the fact that HCM mayfirst present in the elderly.43 Our recommendation is that ifthe diagnosis has not been made previously but issuspected, it is prudent to delay all but the most urgentsurgery until a full assessment can be completed. Forexample, a case report by Angelotti et al44 discussed a 68-year-old patient having a repair of a fractured radius after abicycle accident. In preoperative assessment, a murmurwas auscultated, and an echocardiogram revealed HCMwith a basal LVOT gradient of 64 mm Hg. The case waspostponed until the patient's condition was optimized withthe use of β-blockade and fluid loading, resulting in alower gradient and a more favorable clinical condition. Inanother case report, a soft systolic murmur was heard at theleft sternal border preoperatively in a 73-year-old womanscheduled for an open reduction and internal fixation ofthe right hip.45 During the procedure, the murmurworsened with blood loss and mild hypotension, leadingthe clinicians to suspect HOCM, which improved withfluid resuscitation. The diagnosis was confirmed postop-eratively by echocardiography. Physical signs can be ofgreat value in patients with HOCM because they may shedlight on the severity of the obstruction and the patient'sgeneral functional status. The presence of a fourth heart

sound may indicate poor ventricular compliance, whereasa splitting of the second heart sound can signify LVobstruction.9,29,42 Auscultation of a murmur can differen-tiate if the outflow obstruction is latent or basal. A lateejection systolic murmur heard at the left sternal border orapex will be present at rest with basal obstruction and willincrease in intensity with provocation, such as withmaneuvers that decrease afterload or venous return(standing, Valsalva, amyl nitrate).9,29,42 In addition,many patients with severe outflow obstruction will alsohave mitral regurgitation, either from SAM of the anteriormitral leaflet or from anomalous insertion of papillarymuscles into the mitral valve leaflets.9,14,18,29,42

Once the diagnosis is established and the severity of theobstruction is known, the anesthesiologist must minimizepotential intraoperative worsening of the obstruction.Medical optimization with negative inotropes such as β-blockers calcium channel blockers, or disopyramideshould be considered and should be continuedperioperatively.46 If the patient is not on negativeinotropes already, premedication with β-blockers such asmetoprolol47 is acceptable, with the goal being heart ratesbetween 60 and 65 beats/min.4 Patients should beinstructed to continue their medications through thefasting period. These agents will prevent tachycardia andincreased contractility, both of which can exacerbate theLVOT obstruction. Preloading with crystalloid to expandthe intravascular volume will mitigate anesthesia-inducedhypotension and minimize the adverse effects of positivepressure ventilation on preload.44,48 Benzodiazepines areuseful because they blunt the sympathetic response, hencepreventing anxiety-induced tachycardia and increasedsystemic vascular resistance. The use of glycopyrrolateand atropine should be avoided due to their potential fortachycardia, and scopolamine may be used if anantisialogue is required.49

Intra-operative management

Outcomes in well-prepared patients with HOCM aregenerally good. The most feared complication relating toanesthesia is exacerbation of LVOT obstruction. Thepotential for LVOT obstruction may be reduced bymaintaining sinus rhythm, adequate preload and afterload,and suppressing sympathetic stimulation. With that inmind, Chang et al50 reported that severe complications ofHCM such as cardiac arrest and refractory shock occurredin 10 of 69 reported cases. They concluded that the relativerisk of anesthesia is low but that unexpected complicationscan occur. In another report, Haering et al32 reportedadverse events in 57% of subjects with HCM undergoingmajor surgery and 26% in those undergoing minorsurgery; this was primarily due to treatable heart failurein 16%—overall complications were characterized as mildwith no deaths.

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Once in the operating room, a number of anestheticoptions are deemed safe. Reports have cited the use offentanyl, along with thiopentone,47 propofol,46 andetomidate,51 as the hypnotics of choice, with each onetitrated slowly to avoid large swings in blood pressure.Vasopressors such as phenylephrine, devoid of inotropicand chronotropic effects, can be useful in treating suddenhypotension.41 The primary goal during induction is toblunt the sympathetic response to stimulation whileconcurrently achieving optimal intubating conditions.Tachycardia during direct laryngoscopy can be preventedby pretreatment with intravenous metoprolol or esmololbefore intubation.46 This practice is recommended,especially in patients with history of heart failuresymptoms, angina, or HCM-related syncope or highresting gradients. Other comorbidities such as hepatic orrenal failure should be considered when choosing musclerelaxants, especially when it comes to their vagolytic andmuscarinic effects. Vecuronium has been deemed as anacceptable agent.32 For the maintenance of anesthesia,volatile agents may have a favorable effect because of theirmyocardial depression. Case reports have mentioned thesuccessful use of isoflurane, 51 halothane, 47 andsevofulrane.44 Poliac et al49 suggested that sevofluranemay be superior to the use of isoflurane and desflurane dueto the latter's tendency to increase heart rate. In the samereport, nitrous oxide was deemed less favored due to itspropensity to increase pulmonary artery pressures, al-though others have used nitrous oxide successfully inpatients with HCM.47,48 Volatile agents and opioids suchas fentanyl or remifentanil may be titrated to achieveadequate anesthesia and analgesia. Episodes of hypoten-sion can be treated with α1-agonists (eg, phenylephrine)and fluids. Poliac et al49 argue against the use of agentswith β-adrenergic activity, such as dopamine, dobutamine,or isoproterenol, due to their positive inotropic effects thatmay result in LVOT obstruction.

Poliac et al49 recommend that acute episodes of atrialfibrillation be immediately reversed with direct currentcardioversion, rather than pharmacologic rate control,because ventricular filling is so dependent on atrialcontraction. Because patients with LVOT obstructioncannot tolerate a significant drop in preload, one casereport described the use of a DDD pacemaker inpreserving rhythm related preload with a subsequentlowering of the LVOT gradient from 100 to 6 mm Hgpost–pacemaker placement.52,53 Thus, it is important notto inactivate a DDD pacemaker during anesthesia when ithas been placed for gradient reduction.47,54

In addition to standard American Society of Anesthe-siologists monitors, most case reports use invasiveintravascular blood pressure monitoring because patientswith HCM may decompensate with even the briefestepisode of hypotension. Data regarding the use of centralvenous and pulmonary artery catheters are scant. In onecase report, central venous pressure (CVP) monitoring was

used; however, readings may not have been reliable due toabnormalities in LV compliance.51 In addition, pulmonarycatheter placement has been associated with arrhythmiasthat may adversely affect hemodynamics in patients withHOCM, particularly if sustained.47,54 Pulmonary capillarywedge pressure may also not be accurate monitor of LVfunction, especially in the presence of mitral regurgitation.Lastly, considering that the benefits of pulmonary arterycatheters do not outweigh the harm,25 it would be prudentto abstain from their routine placement, as well as that ofCVP monitors. With that said, others have advocated forthe placement of CVP monitors and pulmonary arterycatheters, especially in the parturient patient,55,56 and it isat the discretion of the anesthesiologist to decide if the prosoutweigh the cons.

Transesophageal echocardiography (TEE) has longbeen advocated for the use in cardiac surgery and isespecially useful in patients with HOCM undergoing amyectomy or noncardiac surgical procedures.57 During amyectomy, TEE is useful in determining the extent of therequired resection, evaluating structural abnormalities ofthe mitral valve, evaluation of residual post–myectomyobstruction, and post–pump run mitral regurgitation. Innoncardiac surgery, TEE allows for the continuousmonitoring of intravascular status by measurement ofinferior vena cava size and collapse, tricuspid jetregurgitatant velocity, and myocardial function; thesefactors can be especially helpful in patients with HOCMbecause regularized preload and afterload are 2 criticalfactors for preventing the exacerbation of LVOT obstruc-tion. One case report illustrates how an intraoperative TEEdiagnosis of unknown HOCM led to a successfultreatment with fluid resuscitation, β-blockers, andphenylephrine.58 Another case report used intravenousdisopyramide after a patient became acutely hypotensiveafter severe blood loss and the development of subsequentLVOT obstruction and SAM.59 Furthermore, becausemore general surgery procedures are performed laparos-copically, it would be prudent to use a TEE in a patientwith HOCM—because the pneumoperitoneum com-presses the venous vasculature, it may reduce preloadand cause a reflex tachycardia, therefore exacerbatingLVOT obstruction. In one case report, Popescu andPerrino60 reported on a patient with HCM who experi-enced hypotension with ST depressions intraoperatively.Normally, such a scenario would include therapy withnitroglycerin and inotropes. However, the advantage ofhaving the TEE was that LVOT obstruction was diagnosedand the pathology was, instead, corrected with fluids, β-blockers, and phenylephrine.

There has been concern regarding the use of regionalanesthesia in patients with HOCM because of the potentialfor sympathetic induced vasodilation, a reduction inpreload, and the potential for tachycardia.41,61 However,general anesthesia also presents its unique risks, and thedecision on which anesthetic type is used needs to be

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weighed against the potential risks and benefits in specificpatients. Much of these data stem from case reports inparturient patients.

As will be discussed, neuraxial anesthesia has beenused successfully in parturients. However, pregnancypresents a challenge for patients with HOCM because ofthe physiologic changes it causes. For instance, aortocavalcompression, particularly in late pregnancy, may cause anacute decrease in preload and a reflex tachycardia, bothdeleterious to patients with HOCM. Furthermore, aspregnancy progresses, there is a decrease in systemicvascular resistance as a result of both the elaboration ofprostacyclin and the growth of the placental unit, whichacts as a low-pressure shunt. In addition, increasedmineralocorticoid activity increases salt retention andmay predispose the patient to intravascular volumechanges, which may not be well tolerated by an alreadynoncompliant left ventricle. The goals of anestheticmanagement are to prevent tachycardia and hypertensionrelated to painful uterine contractions, maintain volumestatus and mitigate the risk of hypotension, and reduceValsalva maneuvers during the second stage with aplanned instrumental delivery using good perineal anes-thesia and relaxation. The most critical time is immedi-ately postdelivery when there is an uncontrolledautotransfusion of blood into the central compartmentand increase in systemic resistance due to rapid involutionof the uterus and the potential for blood loss.62 Indeed,there are case reports involving patients who developedpulmonary edema after excessive fluid resuscitationduring delivery.56 In addition, the potential for cardiacischemia is ever present due to the increased oxygendemands of an already hypertrophied myocardium. Onecase report describes a woman with HOCM who had amyocardial infarction while under spinal anesthesiaundergoing a cesarean delivery.63 Because vaginaldelivery will force the patient to “bear down” (Valsalva),therefore increasing the LVOT obstruction,48 generalanesthesia has been more widely used for delivery ofpregnant women with HOCM. Furthermore, this may bebecause these women have a greater likelihood of cesareandelivery.64 Indeed, between 1997 and 2001, 75% ofpatients with HCM in the United Kingdom delivered bycesarean delivery and received general anesthesia despitethe fact that the latter is associated with a greater risk ofmaternal mortality among all comers as compared withregional anesthesia.65,66

Historically, for the reasons previously mentioned,neuraxial anesthesia has been frowned upon.41,44,61,67 Asrecently as 2011, Stergiopoulos et al65 report that evenepidural anesthesia should be avoided. Simultaneously,because our management of these patients has improvedimmensely over the past decades, many case reports showthat a successful administration of neuraxial anesthesia canbe accomplished as long as accompanied by carefulmonitoring and speedy correction of adverse complica-

tions. Furthermore, evidence shows that most maternaldeaths relating to anesthesia occur during generalanesthesia for cesarean delivery.66 The safety of neuraxialtechnique is most extensively established in 2 recentarticles that do show that pregnancy in women with HCMis generally well tolerated.62,64 Thaman et al62 showedthat only 28% of patients reported cardiac symptomsduring pregnancy, with more than 90% of them reportingsimilar symptoms before pregnancy. Furthermore, only10% of patients had symptom deterioration. Similarly,Autore et al64 do conclude that although absolute maternalmortality is low, it is increased in comparison with thegeneral population. These women usually have symptomsbefore pregnancy, however, and have a strong familyassociation of sudden cardiac death. In addition, the studyestablished that clinical deterioration is twice as likely inthose with an LVOT obstruction.

There have been numerous reports of successfulneuraxial anesthesia on parturient patients whether forcesarean delivery or vaginal delivery. Multiple casereports describe vaginal deliveries with the use of acombined spinal epidural,55,68 conventional epidural,69

and continuous spinal anesthesia (solely with intrathecalopioids).70 In regard to caesarian delivery, Autore et al71

describe the use of a continuous epidural for the anestheticmanagement, whereas Ishiyama et al72 report uncompli-cated caesarian delivery under combined spinal andepidural anesthesia. Although the aforementioned casesillustrate that neuraxial anesthesia can be administeredsafely and is effective and safe in patients with HOCM,there are no specific guidelines set forth to guide theanesthesia community. Considering the lack of random-ized controlled trials, the anesthetic management of theparturient with HOCM should be individualized based onmaternal and fetal condition.

Postoperative considerations

The same considerations that guide the managementof patients with HOCM intraoperatively must be appliedpostoperatively. Hence, it would seem prudent thatpatients with HOCM remain in a monitored setting untilstable, depending on the extent of surgery and clinicalcondition. Emergence from anesthesia is often associatedwith an increased sympathetic tone, similar to induction,which can exacerbate the LVOT obstruction. The goal isto prevent tachycardia. Meticulous attention to painrelief is essential. If that fails to control tachycardia, anegative chronotrope should be given, such as intrave-nous metoprolol in incremental doses of 5 mg up to amaximum of 15 mg. Alternatively, esmolol may be usedbut is not as effective in the long term; overall, doses tokeep the resting heart rate around 60 beats/min arenecessary. With both drugs, the heart rate may be usedas a “biomarker” to assure adequate dosing. A

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misconception in the postoperative period is to withholdβ-blockade. This is especially common in patients withborderline systolic blood pressures of 85 to 95 mm Hg,where the relative hypotension may be due to worseningobstruction caused by tachycardia more than anythingelse. If a clinical situation is under debate, urgentechocardiography showing a good LV systolic functionbut high LVOT gradients may clarify the urgent need forintravenous β-blockade. The patient's oral regimenshould be restarted as soon as bowel function allows.In the parturient, caution should be exercised in theadministration of oxytocin, particularly in bolus doses,because this may precipitate vasodilation with reflextachycardia.73 A slow infusion is preferred.71

Fluid shifts may occur for several days after surgery,especially if associated with sepsis. Careful assessment offluid status is recommended particularly because conges-tive heart failure may occur. Lastly, patients undergoingcardiac procedures may need postoperative controlledventilation requiring additional monitoring. Overall, thereare no clear-cut algorithms for the admission of patientswith HOCM to the intensive care unit postoperatively;however, based on several reports,32,41,74 it would beprudent to assess each patient on an individual basis andtake into account the type of surgery, the length of thecase, and the patient's preoperative status. We generallyrecommend cardiac monitoring for at least 24 hours.

Conclusions

With advances in clinical practice, it is likely that wewill see more patients with HOCM requiring anesthesiaand surgery. The anesthesiologist must be knowledgeableabout the highly specific pathophysiology of this illness asit relates to preoperative optimization, anesthetic manage-ment, and postanesthesia care. Maintenance of intravas-cular volume, sinus rhythm, and slow rate, as well asblunting of the sympathetic response and avoidinginotropes, is at the core of management to minimizeperioperative adverse outcomes.

Statement of Conflict of Interest

All authors declare that there are no conflicts of interest.

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