European Journal of Echocardiography Advance Access originally published online on July 11, 2008
European Journal of Echocardiography 2008 9(6):855-860; doi:10.1093/ejechocard/jen197
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2008. For permissions please email: journals.permissions@oxfordjournals.org
Anomalous insertion of the papillary muscle causing left ventricular outflow obstruction: visualization by real-time three-dimensional echocardiography
Hyun Suk Yang,
Kwan S. Lee,
Hari P. Chaliki,
Henry D. Tazelaar,
Joan L. Lusk,
Krishnaswamy Chandrasekaran* and
A. Jamil Tajik
Division of Cardiovascular Diseases, Mayo College of Medicine, Mayo Clinic, 13400 East Shea Boulevard, Scottsdale, AZ 85259, USA
Received 21 March 2008; accepted after revision 4 June 2008; online publish-ahead-of-print 11 July 2008.
* Corresponding author. Tel: +1 480 342 3178. E-mail address: kchandra{at}mayo.edu
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Abstract
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Anomalous insertion of the papillary muscle (PM)/chordae tendineae
is a rare but important cause of dynamic left ventricular outflow
tract (LVOT) obstruction in patients with hypertrophic cardiomyopathy
or cardiac amyloidosis. These anomalies are often challenging
to diagnose with 2-D Echo, yet accurate diagnosis is critical
in determining whether to proceed with an extended septal myectomy
instead of a standard septal myectomy for relief. We report
two cases of anomalous insertion of the PM causing LVOT obstruction
with diagnosis facilitated by real-time 3-D echocardiograms.
Keywords: Papillary muscle; Hypertrophic cardiomyopathy; Amyloidosis
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Introduction
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Anomalies of the papillary muscle (PM) have been reported in
up to 13% of necropsy specimens of obstructive hypertrophic
cardiomyopathy (HOCM).
1 The reported incidence of congenital
anomalous PM is 1% in otherwise normal patients.
1 Anomalous
insertion of the PM/chordae tendineae can result in left ventricular
outflow tract (LVOT) obstruction. These anomalies are often
challenging to diagnose with 2-D Echo. We report two cases of
anomalous insertions of PM/chordae tendineae causing LVOT obstruction
with diagnosis facilitated by real-time 3-D echocardiograms
(RT3DE).
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Case 1
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A 43-year-old man presented intermittent dizzy spells over the
last few years, particularly when climbing stairs or standing.
He had a family history of coronary artery disease. A subsequent
echocardiogram demonstrated increased septal thickness, and
his cardiac catheterization found normal coronary arteries and
normal left ventricular (LV) function with a maximum LVOT gradient
of 25 mmHg. He was referred to our institution for further evaluation
of possible HOCM. Physical examination revealed an S4 with a
grade II/VI systolic ejection murmur, decreasing with squatting
and increasing during the Valsalva manoeuvre. A transthoracic
2-D echo revealed asymmetric interventricular septal hypertrophy
of LV walls (septum 22 mm and posterior wall 14 mm at end-diastole).
At rest, there was no significant LVOT obstruction; during amyl
nitrite provocation, there was significant LVOT obstruction
with systolic anterior motion (SAM) of the anterior mitral valve
leaflet (AMVL) (
Figures 1 and
2) with increasing mild mitral
regurgitation (MR). RT3DE clarified the spatial relationship
of an abnormal PM, which connected directly to the base of the
AMVL (A2/A3) (
Figure 3), tethering the AMVL, and producing
dynamic LVOT obstruction. We recommended family screening, and
prescribed beta blockers and a statin while discontinuing Verapamil,
and planned a follow-up in order to reassess his haemodynamics
and pharmacotherapeutic regimen.
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Figure 1 2D and colour Doppler transthoracic echocardiogram of the apical long-axis view reveals flow acceleration with aliasing at the level of dynamic obstruction (arrowheads) during the amyl nitrite inhalation.
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Figure 2 Continuous wave Doppler tracing of the LVOT shows the peak and mean pressure gradient at rest (12/6 mm Hg), during the Valsalva manoeuvre (40/15 mm Hg), and with amyl nitrite (64/19 mm Hg). During the amyl nitrite inhalation, heart rate increased from 69 to 114 bpm with a high velocity late-peaking pattern.
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Figure 3 RT3DE demonstrates the origin of the anomalous papillary muscle in the postero-medial (empty arrowhead) and its abnormal insertion at the base of AMVL (filled arrowhead). IVS, interventricular septum; LA, left atrium; Ao, aorta.
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Case 2
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A 66-year-old man presented shortness of breath on minimal exertion
for several months. Physical examination showed a grade III/VI
systolic ejection murmur along the left sternal edge. A transthoracic
2-D echo revealed increased concentric LV wall thickness with
an ejection fraction of 40%, severe bi-atrial enlargement with
elevated LV filling pressure (E/e' 17), and thickened right
ventricular walls (10 mm).There was a significant pressure gradient
at the sub-aortic level (
Figure 4), with an anomalous PM.
No prominent valvular SAM or increase in the amount of MR was
noted during the amyl nitrite provocation (
Figure 5). He
exercised on the supine bike for 5 min to a maximum of 50 W
with a peak LVOT gradient of 31 mm Hg. RT3DE revealed a severely
thickened anomalous PM directly inserted into the base of the
AMVL (A2/A3) resulting in LVOT narrowing (
Figure 6 and
Supplementary data online, Movie I). His right ventricular endomyocardial
biopsy showed prominent interstitial and nodular amorphous eosinophilic
deposits consistent with amyloid (confirmed by a positive sulfated
alcian blue stain) (
Figure 7). His haemodynamics is consistent
with significant right heart failure with restrictive LV filling—the
pulmonary artery pressure was 55/27 mm Hg, and the pulmonary
capillary wedge pressure 27 mm Hg. He was finally diagnosed
with AL cardiac amyloidosis associated with multiple myeloma
Ig G kappa. At the time of this diagnosis, he was not a candidate
for stem cell transplantation or systemic intravenous chemotherapy
secondary to his poor Eastern Cooperative Oncology Group (ECOG)
performance status. After 4 months had passed from the pathologic
diagnosis of cardiac amyloidosis, we were informed of his death
from the hospice centre.
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Figure 4 Pulsed wave Doppler tracing along the LVOT (A–C) points out the obstruction level with a high velocity profile (C)—no mid cavity of LV obstruction is demonstrated. A 2-D echo (D) with colour Doppler (E) shows flow acceleration with aliasing at the sub aortic level.
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Figure 5 Continuous wave Doppler tracing of the LVOT shows the peak pressure gradient at rest (29 mm Hg), during the Valsalva manoeuvre (31 mm Hg), and with amyl nitrite (49 mm Hg) with an uniform systolic Doppler spectral profile.
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Figure 6 RT3DE demonstrates the thickened postero-medial papillary muscle directly inserted at the base of the AMVL (arrows) (Supplementary data online, Movie I). IVS, interventricular septum; LV, left ventricle; LA, left atrium; Ao, aorta.
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Discussion
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The diagnosis of an anomalous PM leading to dynamic LVOT obstruction
can be challenging with 2-D echo. Due to the oblique course
of the PM, complete delineation of the muscle frequently requires
multiple off-axis images and is time-consuming. Compare 2-D
echoes of one optimal plane with flow acceleration and aliasing
in LVOT (
Figure 4d) where an anatomical discontinuity appears
between the base of the mitral annulus and the LV walls; RT3DE
(
Figure 6) reveals entire course of PM/chordae tendineae,
including the anomalous insertion at the base of AMVL. RT3DE
provides ease of complete anatomical imaging of the anomalous
PM.
The mechanisms leading to dynamic LVOT obstruction are complex. In HOCM, substantial variations in mitral valvular anatomy have been reported.2 Amongst these, anomalous PM has been described as causing dynamic obstruction, leading to recurrent LVOT obstruction after septal myectomy for obstructive HOCM.3 It is, therefore, clinically important to carefully rule out the presence of an abnormal PM causing dynamic obstruction, a finding which would require more interrogation of the subvalvular region during the operation and an extended septal myectomy4,5 instead of a standard septal myectomy for relief. In the presence of muscular mid-cavity obstruction (due to the anomalous PM/chordae tendineae which is inserted directly into the base of mitral valve), a much more substantial myectomy is required by combining the standard operation with an extended mid-ventricular resection and an additional resection around the bases of the PM. So all areas of PM fusion to the septum or ventricular walls are divided, and anomalous chordal structures and fibrous attachments of the mitral leaflets to the ventricular septum or free wall are divided or excised.4,5
We also reported an amyloid heart disease with LVOT obstruction secondary to thick and anomalous insertion of PM. There have been a few reports of patients with cardiac amyloidosis and dynamic LVOT obstruction,6,7 but none related to anomalous PM. A thickened PM was identified by 2-D echo in a case series of 5/13 patients with biopsy-proven amyloidosis.8 In case 2, although the mechanism is not clearly defined, it is reasonable to consider amyloid infiltration on the anomalous PM. The role of amyloid infiltration along with the anomalous PM insertion and stiffening of the mitral leaflet can be emphasized on different haemodynamic and muscle mechanics.1 During the amyl nitrate provocation, case 1 showed marked SAM with an increase of MR extent and of the pressure gradient along the LVOT with late-peaking systolic continuous wave Doppler (Figure 2). However, in case 2, the obstruction level is closer to the thick, rigid anomalous PM insertion point with less SAM and without the increase of MR extent and less increase of the pressure gradient showing the uniform systolic continuous wave Doppler spectral profile (Figure 5).2 Comparison of the negative strain of the abnormal PM between cases 1 and 2 reveals relatively less regional contraction in case 2—the PM thickening reflecting amyloid infiltration rather than contractile muscle cells (Figure 8). Despite the overall poor prognosis of severe cardiac amyloidosis, there are several reported cases of attempts to reduce the dynamic LVOT obstruction by various methods including CABG with septal myectomy9 or isolated percutaneous transluminal septal myocardial ablation.10 It would be important to identify the presence of anomalous PM—simply resolving the thickened septal muscle may not relieve the pressure gradient.
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Figure 8 Comparison of the strain curves of the anomalous papillary muscle between the two cases. The peak negative strain of case 1 (HOCM) is –38.0%, whereas that of case 2 (Cardiac amyloidosis) is –6.3%. LV, left ventricle, AMVL, anterior mitral valve leaflet.
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Sometimes the LVOT obstruction related to the congenital PM
anomaly could be found in parachute or parachute-like mitral
valves due either to a huge single PM and its relation to LVOT
or to chordae tendineae confluence on a single PM and its relationship
to LVOT.
11 Echocardiography establishes the diagnosis—the
typical parachute deformity of the mitral valve is best demonstrated
in the short-axis view of the mitral valve at the mid and apical
segments of the LV revealing a single PM accepting all the chordae
tendineae insertions.
In summary, anomalous insertion of the PM/chordae tendineae is a rare but important cause of dynamic LVOT obstruction in patients with HOCM or cardiac amyloidosis. To our knowledge, this is a first report of the anomalous insertion of PM causing LVOT obstruction in a patient with biopsy-proven cardiac amyloidosis—we emphasized the role of amyloid infiltration along the anomalous PM. RT3DE provides clear benefits over 2-D Echo in accurate imaging and delineation of the spatial relationship between the anomalous PM and LVOT and should be considered in cases in which the diagnosis is suspected with 2-D Echo.
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Supplementary data
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Supplementary data are available at European Journal of Echocardiography online.
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References
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Abstract
Introduction