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Reorientation of an Obstructive, Hypermobile Papillary Muscle

Intraoperative Echocardiographic Assessment

Coyne, Joseph Thomas, MD; Alfirevic, Andrej, MD

doi: 10.1213/ANE.0b013e3182847d4c
Cardiovascular Anesthesiology: Echo Didactics & Rounds
Free
SDC

Published ahead of print April 4, 2013

From the Department of Cardiothoracic Anesthesiology, Cleveland Clinic Foundation, Cleveland, Ohio.

Accepted for publication November 8, 2012.

Published ahead of print April 4, 2013

The authors declare no conflicts of interest.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.anesthesia-analgesia.org).

Reprints will not be available from the authors.

Address correspondence to Joseph Thomas Coyne, MD, Department of Cardiothoracic Anesthesiology, Cleveland Clinic Foundation, 9500 Euclid Ave., J4-331, Cleveland, OH 44195. Address e-mail to josephthomascoyne@gmail.com.

Written consent for publication was obtained. A 47-year-old man presented with palpitations and exertional dyspnea for surgical reorientation of the papillary muscles (PMs) and possible myectomy. Preoperative transthoracic echocardiogram showed normal biventricular function, moderate mitral regurgitation (MR) associated with amylnitrate-provoked systolic anterior motion, and a left ventricular outflow tract (LVOT) peak instantaneous gradient of 143 mm Hg. Cardiac magnetic resonance imaging revealed a hypertrophied, apically displaced, and hypermobile anterolateral PM.

Intraoperative transesophageal echocardiography (TEE) midesophageal views confirmed the presence of a hypermobile anterolateral PM (Fig. 1, A and B) (Video 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A520). The PM tethered the anterior mitral valve (MV) leaflet with a short and thickened chordae, causing predominantly centrally directed MR. Transgastric 2-chamber images showed a hypertrophied anterolateral PM in its longitudinal axis, displaced anteriorly and dragging the anterior MV leaflet into the LVOT during systole (Fig. 2). The diastolic basal anteroseptal thickness was measured as 1.3 cm (normal male: 0.6–1.0 cm; mild 1.1–1.3 cm; moderate 1.4–1.6 cm; severe >1.7 cm) at the contact point, and myectomy was not performed. Using an aortotomy approach, the muscle was reoriented to a more posterior position, decreasing its mobility toward the LVOT (Figs. 1C and 3) (Video 2, see Supplemental Digital Content 2, http://links.lww.com/AA/A521). Postprocedure TEE evaluation using a continuous wave Doppler directed through the LVOT and aortic valve revealed a peak instantaneous gradient of 27.6 mm Hg during isoproterenol infusion provocation at 20 μg/kg/min and resting gradient of 11 mm Hg. The remainder of the procedure and hospitalization were unremarkable.

Figure 1

Figure 1

Figure 2

Figure 2

Figure 3

Figure 3

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DISCUSSION

Atrioventricular valve leaflets and chordae are derived from atrioventricular cushion tissue, which is fused by 5 weeks’ gestation. The cushions initiate delaminating in weeks 6 to 7, creating leaflets that remain connected to PMs. Gaps begin to form in the ventricular cushion layer at 10 weeks, later becoming interchordal spaces.1 Errors in this process, caused by abnormal blood flow or autosomal dominant sarcomeric protein gene mutations, form the basis for various congenital malformations of the valve and subvalvular apparatus.1

Patients with hypertrophic cardiomyopathy (HCM) usually present with hypertrophied interventricular septum, accompanied by systolic anterior motion of the MV causing a dynamic LVOT obstruction. However, dynamic LVOT obstruction due to the anomalous position and orientation of the PMs is increasingly recognized in patients with minimal or no basal septal hypertrophy.2,3 Kwon et al.3 demonstrated more than a 4-fold increase in frequency of anteroapical displacement of the anterolateral PM in patients with HCM. The laxity and apico-anterior position of the muscle enables systolic dragging and tethering of the anterior MV leaflet into the LVOT. Furthermore, anatomically bifid PM heads lead to narrowing of the LVOT and subsequent obstruction.2 Increased length of the anterior MV leaflet or the presence of septal hypertrophy may further increase drag effect.3 Surgical reorientation of the PM is performed by running a tethering suture from the posterior myocardial wall to the anterolateral PM. The tethering effect reduces hypermobility and reorients the muscle in a posterior direction further away from the LVOT.2

Preoperative cardiac magnetic resonance imaging is superior to echocardiography in imaging morphologic patterns of HCM during preprocedural planning.4 Intraoperative echocardiography focuses on evaluating the etiology and mechanism of dynamic LVOT obstruction. Multiple measurements of the basal interventricular septum are needed to accurately assess the appropriateness for surgical myectomy. Visible aspects of the interventricular septum vary with depth of TEE probe insertion. Starting at midesophageal 5-chamber view and advancing (or retroflexing) the TEE probe to 4-chamber view may delineate the entire width of the basal and midventricular septum from anterior to inferior. In addition, the midesophageal long-axis view studies the basal and midventricular anterior septum. Septal thickness <16 mm increases the risk of an iatrogenic ventricular septal defect after myectomy4 and should redirect the focus of attention onto a different pathologic entity.

Interrogation of PM size and mobility is initially obtained from the midesophageal 4-chamber and long-axis views. The chordae lie in parallel relationship with ultrasound beams and require subtle manipulations of probe turning and omniplane angle rotation. Anomalous PM is attached to the anterior leaflet via short, thick chordae. This results in a tethering effect of the anterior MV leaflet. Thus, the MR jet is more centrally directed during LVOT obstruction. This central jet opposes the posteriorly and laterally directed MR jet seen with classic septal HCM or after MV repair,4,5 which is important in differentiating these etiologies. The muscle is large, mobile, and in close relationship with the interventricular septum in the transgastric short-axis view. Subtle adjustments to the transgastric 2-chamber view best visualize the PMs and thickened chordae in their longitudinal axis. The hallmarks of LVOT obstruction include turbulence with color flow Doppler and a late-peaking spectral envelope obtained with continuous wave Doppler. Septal thickness is measured in midesophageal long-axis view during diastole at the point of leaflet-septal contact.6 After separation from cardiopulmonary bypass, the LVOT gradient and associated MR jet severity and direction are evaluated with isoproterenol provocation. Criteria for unsatisfactory myectomy include persistent resting (>30 mm Hg) and provoked (>50 mm Hg) LVOT gradients or MR more than moderate in severity.7 Presence of laminar flow is consistent with the absence of a significant obstruction. The transgastric short-axis and long-axis views best provide images of the stabilized PM tethered in a position away from the LVOT.

In summary, intraoperative TEE is a diagnostic and confirmatory imaging modality for obstructive, hypermobile PM as well as evaluation of the reorientation repair.

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DISCLOSURES

Name: Joseph Thomas Coyne, MD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Joseph Thomas Coyne approved the final manuscript.

Name: Andrej Alfirevic, MD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Andrej Alfirevic approved the final manuscript.

This manuscript was handled by: Martin J. London, MD.

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REFERENCES

1. Oosthoek PW, Wenink AC, Vrolijk BC, Wisse LJ, DeRuiter MC, Poelmann RE, Gittenberger-de Groot AC. Development of the atrioventricular valve tension apparatus in the human heart. Anat Embryol. 1998;198:317–29
2. Kwon DH, Smedira NG, Thamilarasan M, Lytle BW, Lever H, Desai MY. Characteristics and surgical outcomes of symptomatic patients with hypertrophic cardiomyopathy with abnormal papillary muscle morphology undergoing papillary muscle reorientation. J Thorac Cardiovasc Surg. 2010;140:317–24
3. Kwon DH, Setser RM, Thamilarasan M, Popovic ZV, Smedira NG, Schoenhagen P, Garcia MJ, Lever HM, Desai MY. Abnormal papillary muscle morphology is independently associated with increased left ventricular outflow tract obstruction in hypertrophic cardiomyopathy. Heart. 2008;94:1295–301
4. Gersh BJ, Maron BJ, Bonow RO, Dearani JA, Fifer MA, Link MS, Naidu SS, Nishimura RA, Ommen SR, Rakowski H, Seidman CE, Towbin JA, Udelson JE, Yancy CWAmerican College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. . 2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2011;58:e212–60
5. Kahn RA, Mittnacht AJ, Anyanwu AC. Systolic anterior motion as a result of relative “undersizing” of a mitral valve annulus in a patient with Barlow’s disease. Anesth Analg. 2009;108:1102–4
6. Sherrid MV, Chaudhry FA, Swistel DG. Obstructive hypertrophic cardiomyopathy: echocardiography, pathophysiology, and the continuing evolution of surgery for obstruction. Ann Thorac Surg. 2003;75:620–32
7. Marwick TH, Stewart WJ, Lever HM, Lytle BW, Rosenkranz ER, Duffy CI, Salcedo EE. Benefits of intraoperative echocardiography in the surgical management of hypertrophic cardiomyopathy. J Am Coll Cardiol. 1992;20:1066–72
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Clinician’s Key Teaching Points

By Martin M. Stechert, MD, Donald C. Oxorn, MD, and Martin J. London, MD

  • During early embryologic development (5–19 weeks), papillary muscles (PMs) are sculpted out of the left ventricular wall. Developmental variants may include a single PM, accessory PMs, abnormal size and mass, or malposition. Once thought to be solely on the basis of septal hypertrophy and Venturi-mediated displacement of the anterior mitral leaflet, left ventricular outflow tract obstruction (LVOTO) due to hypertrophic obstructive cardiomyopathy is now recognized to occur where PMs have developed abnormally and the septum is of normal or minimally increased thickness. Thus, corrective surgery may now include septal myomectomy and/or reorientation of a displaced PM.
  • Intraoperative transesophageal echocardiography (TEE) is most frequently used to measure septal thickness, quantify the LVOTO, and assist surgical decision-making regarding the primary pathophysiologic mechanisms. After PM relocation, postbypass TEE examination should confirm the absence of systolic anterior motion (SAM) of the anterior mitral valve leaflet, adequate reduction in mitral regurgitation (MR) and LVOTO, and exclude surgical complications such as new ventricular septal defect or aortic valve injury.
  • In this case, an apically displaced, hypermobile, anterolateral PM led to increased tethering of the anterior mitral valve leaflet into the left ventricular outflow on systole, resulting in LVOTO and SAM. Consistent with this pathology, a posterior directed MR jet was also noted. PM relocation was performed and myomectomy was not deemed necessary. The LVOTO, SAM, and MR were all ameliorated with this approach.
  • Hypertrophic obstructive cardiomyopathy surgery has long been recognized as a category I indication for intraoperative TEE. The current case illustrates that although septal myomectomy is usually the procedure of choice, mitral valvular, subvalvular, and PM abnormalities may dictate alternate surgical approaches.

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