CHALLENGING CASES

Hypertrophic Cardiomyopathy with Right VentricularOutflow Tract and Left Ventricular IntracavitaryObstruction

Rabiya Malik, M.D., Martin S. Maron, M.D., Hassan Rastegar, M.D., and Natesa G. Pandian, M.D.

Cardiovascular Center, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts

Obstruction of the right ventricular outflow tract (RVOT) is a rare finding in hypertrophic cardiomyopa-thy (HCM) patients unlike left ventricular outflow tract (LVOT) obstruction. Although there are guide-lines that aid in clinical decision making in patients with LVOT obstruction, there are none addressingRVOT obstruction. As RVOT obstruction may pose serious clinical implications similar to LVOT obstruc-tion, appropriate medical and surgical management is very important. A unique phenotype of HCMwith RVOT obstruction in conjunction with left ventricle (LV) intracavitary obstruction is discussed.(Echocardiography 2014;31:682–685)

Key words: hypertrophic cardiomyopathy, right ventricular outflow tract obstruction, left ventricularintracavitary obstruction, biventricular obstruction

Hypertrophic cardiomyopathy (HCM) patientsmostly present with dynamic obstruction to leftventricular outflow tract (LVOT) due to asymmet-rical septal hypertrophy, systolic anterior motion(SAM) of the mitral valve, and SAM-septal con-tact.1–3 Although abnormalities of right ventricu-lar (RV) wall thickness and mass have beenreported in HCM patients,4–8 the presence ofright ventricular outflow tract (RVOT) obstructionremains an infrequent finding. This report willpresent a rare and unique phenotype of HCMwith RVOT obstruction accompanied by leftventricle (LV) intracavitary obstruction.

Case Presentation:A 37-year-old female was referred to our HCMClinic for evaluation regarding her managementstrategies for HCM. Her original history started adecade ago when she developed exertional dysp-nea and chest pain. At that time, she was foundto have obstructive HCM and underwent left-sided surgical myectomy, which was followed bya long symptom-free period. However, morerecently, she started developing debilitatingsymptoms of exertional dyspnea, fatigue, andpalpitations again. Beta blockade and calciumchannel blockade therapy did not alleviate hersymptoms. An implantable cardioverter defibrilla-tor (ICD) was placed following an episode of syn-

cope. However, she subsequently had severalepisodes of presyncope as well as loss of con-sciousness without any evidence of arrhythmiasdetected on her ICD. The ICD was placed mainlyfor primary prevention of sudden cardiac death.Her father and paternal uncle died young at ages29 years and 16 years, respectively, of unknowncause, presumably HCM.

Transthoracic echocardiography (iE33, Philips,Bothell, WA, USA) showed a hyperdynamic heartwith an ejection fraction of 65%. LV was asym-metrically hypertrophied with a maximum wallthickness of 19 mm in the septum. The mitralvalve was normal in size and function. No SAM ofthe mitral valve was present and therefore, therewas no LVOT obstruction at rest or following Val-salva maneuver. However, an LV intra-cavitarygradient of 40 mmHg was detected, due toopposition of the septum and the LV free wall(Fig. 1 and movie clip S1). Right ventricle wasmoderately hypertrophied with a resting RVOTgradient of 50 mmHg (Figs. 2 and 3 and movieclip S2) and an elevated RV systolic pressure of60 mmHg. Postexercise echocardiographicimaging revealed an increase in LV intracavitarygradient to 65 mmHg with no evidence of a sub-aortic gradient, and an increase in RVOT gradientto 80 mmHg.

Both LV intracavitary and RVOT obstructionhave been reported to present with life-threaten-ing symptoms, either in isolation or in combina-tion with LVOT obstruction.4,5 Hence, the duo ofLV intracavitary and RVOT obstruction was con-sidered to be a deadly combination which

Address for correspondence and reprint requests: Natesa G.Pandian, M.D., Tufts Medical Center, 800 Washington Street,Box#32, Boston, MA 02111. Fax: 617-636-8070;E-mail: npandian@tuftsmedicalcenter.org

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© 2014, Wiley Periodicals, Inc.DOI: 10.1111/echo.12543 Echocardiography

Figure 1. Two-dimensional and Doppler echocardiographic images showing left ventricular intracavitary obstruction. A. Paras-ternal long-axis view showing asymmetrical septal hypertrophy; B. Apical four-chamber view showing opposition of the septumand the left ventricular free wall; C. Apical four-chamber view with color Doppler profile across the left ventricular cavity; D.Continous-wave Doppler recording in the left ventricular cavity showing increased velocity profile consistent with left ventricularintracavitary obstruction. LA = left atrium; LV = left ventricle.

Figure 2. Two-dimensional and Doppler echocardiographic images showing right ventricular outflow tract (RVOT) obstruction.A. Parasternal short-axis view of the RVOT showing obstruction (white arrow); B. Transgastric view depicting narrowing of theRVOT; C. Mid-esophageal right ventricular inflow–outflow view with color Doppler profile across the right outflow tract obstruc-tion; D. Continous-wave Doppler recording across the RVOT showing increased velocity profile consistent with RVOT obstruction.RA = right atrium; RV = right ventricle; PA = pulmonary artery.

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required immediate surgical correction. Follow-ing the plan, the patient underwent an extendedleft-sided septal myectomy through an aortoto-my and resection of the hypertrophied RV muscu-lature through a right ventriculotomy. Afterresection of the hypertrophied RV musculature,the RVOT was reinforced by an acellular xeno-graft patch to create space and prevent theobstruction from recurring. Postoperatively, bothRVOT and LV intracavitary gradients wererelieved. The patient was symptom-free and nomedications were required postoperatively.

Discussion:Obstruction of LVOT is a common finding inHCM patients.1–3 However, RVOT obstructionremains a rare finding despite appreciation ofmorphological abnormalities of RV wall thicknessand mass in HCM patients.6–9 Although there areguidelines to aid in the clinical management of

HCM patients with LVOT obstruction, there arenone addressing RVOT obstruction owing to theinfrequent nature of the pathology. Subpulmonicgradients have been observed in conjunctionwith LV outflow obstruction in the past.8 How-ever, obstruction of RVOT in combination withLV intracavitary obstruction is a unique pheno-typical manifestation of HCM.

Right ventricular outflow tract obstruction hasappeared to be mainly due to hypertrophy of theRV musculature, most frequently the cristasupraventricularis.6,8 Hence, as opposed toLVOT obstruction which is predominantly adynamic obstruction due to SAM of the mitralvalve, RVOT obstruction is mainly a static and fixedmuscular impediment to outflow.8 Obstruction ofRVOT due to protrusion of the hypertrophied sep-tum into the RV cavity or SAM of the tricuspid valvehas not been reported so far. The same mutationsin the cardiac sarcomere that cause phenotypical

Figure 3. Three-dimensional echocardiographic images showing left ventricular intracavitary and RVOT obstruction. A. Apicalfour-chamber view showing left ventricular intracavitary obstruction due to opposition of the septum and the left ventricular freewall; B. Mid-esophageal right ventricular inflow–outflow view depicting RVOT obstruction (arrow); C. En face view of RVOTobstruction during diastole (red arrow); D. En face view of RVOT obstruction during systole (arrow). LA = left atrium; LV = leftventricle; RV = right ventricle; RVOT = right ventricular outflow tract; PA = pulmonary artery.

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expression of LV hypertrophy are considered to beresponsible for RV hypertrophy also.6,10

In conclusion, despite the rare nature of RVOTobstruction, morphological abnormalities of RVare common in HCM.6 Therefore, HCM is agenetic cardiomyopathic process involving boththe left and the right sides of the heart, and toaccurately define and manage this heteroge-neous disease it is important to consider the pres-ence of RV morphological abnormalities as well.

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3. Maron MS, Olivotto I, Betocchi S, et al: Effect of left ven-tricular outflow tract obstruction on clinical outcome inhypertrophic cardiomyopathy. N Engl J Med2003;348:295–303.

4. Butz T, Horstkotte D, Langer C, et al: Significant obstruc-tion of the right and left ventricular outflow tract in apatient with biventricular hypertrophic cardiomyopathy.Eur J Echocardiogr 2008;9:344–345.

5. Kunkala MR, Schaff HV, Nishimura RA, et al: Transapicalapproach to myectomy for midventricular obstruction inhypertrophic cardiomyopathy. Ann Thorac Surg2013;96:564–570.

6. Maron MS, Hauser TH, Dubrow E, et al: Right ventricularinvolvement in hypertrophic cardiomyopathy. Am J Car-diol 2007;100:1293–1298.

7. Recupero A, Di Bella G, Patane S, et al: Right ventricularoutflow tract obstruction in hypertrophic cardiomyopa-thy. Int J Cardiol 2010;144:e56–e57.

8. Maron BJ, McIntosh CL, Klues HG, et al: Morphologicbasis for obstruction to right ventricular outflow in hyper-trophic cardiomyopathy. Am J Cardiol 1993;71:1089–1094.

9. Krecki R, Lipiec P, Piotrowska-Kownacka D, et al: Predom-inant, severe right ventricular outflow tract obstruction inhypertrophic cardiomyopathy. Circulation 2007;116:e551–e553.

10. Marian AJ, Roberts R: Recent advances in the moleculargenetics of hypertrophic cardiomyopathy. Circulation1995;92:1336–1347.

Supporting InformationAdditional Supporting Information may be foundin the online version of this article:

Movie clip S1. Apical four-chamber viewshowing turbulent color Doppler velocity profileacross the left ventricular intracavitary obstruc-tion.

Movie clip S2. Mid-esophageal right ventric-ular inflow–outflow view showing turbulent colorDoppler velocity profile across the right ventricu-lar outflow tract obstruction.

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