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Anesthesia
Seminars in Cardiothoracic and Vascular
http://scv.sagepub.com/content/15/3/112
The online version of this article can be found at:
DOI: 10.1177/1089253211416255
2011 15: 112 originally published online 29 August 2011SEMIN CARDIOTHORAC VASC ANESTH
Christopher W. Connors, Angus A. Christie and Paul W. Weldner
Early Degeneration of a Bioprosthetic Mitral Valve Complicated by a Large Left Atrial Thrombus
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2. Seminars in Cardiothoracic and
Vascular Anesthesia
15(3) 112­–114
© The Author(s) 2011
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DOI: 10.1177/1089253211416255
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Case Report
416255SCVXXX10.1177/1089253211416255Conno
rs et alSeminars in Cardiothoracic and Vascular Anesthesia
1
Maine Medical Center, Portland, ME, USA
Corresponding Author:
Christopher W. Connors, Department of Anesthesiology, Maine
Medical Center, 22 Bramhall Street, Portland, ME 04102, USA
Email: cwconnors@yahoo.com
Early Degeneration of a Bioprosthetic
Mitral Valve Complicated by a Large
Left Atrial Thrombus
Christopher W. Connors, MD1
, Angus A. Christie, MD1
,
and Paul W. Weldner, MD1
Abstract
The authors report the case of a patient with symptomatic early bioprosthetic mitral valve deterioration in the setting
of calcium supplementation. This was further complicated by a large left atrial thrombus despite supratherapeutic
anticoagulation and a previously oversewn left atrial appendage. As mechanical valves are less predisposed to calcification
in comparison with bioprosthetic implants, the patient underwent a mechanical mitral valve replacement in addition to
a left atrial thrombectomy.
Keywords
cardiac anesthesia, mitral valve, transesophageal echocardiography, intraoperative assessment, intraoperative trans-
esophageal echocardiography
A 71-year-old man with a past medical history significant
for a mitral valve replacement, parathyroidectomy, and
paroxysmal atrial fibrillation (PAF) was admitted after
complaining of shortness of breath. Significant surgical
history included a remote parathyroidectomy requiring
daily calcium and vitamin D supplementation and, occur-
ring 7 years prior to presentation, a bioprosthetic mitral
valve replacement as a result of infective endocarditis.
Finally, as a result of PAF that developed in the months
prior to this admission, the patient’s medical regimen
included warfarin. His international normalized ratio
(INR) at presentation was equal to 4.
Evaluation with a transthoracic echocardiogram revealed
preserved left ventricular function, heavily thickened mitral
leaflets with decreased mobility and severely elevated
mitral gradients. The left atrium was mildly enlarged and
there was an absence of mitral regurgitation. Subsequent to
these findings, the patient was scheduled for a mitral valve
replacement.
In the operating suite, 2-dimensional transesophageal
echocardiography confirmed a heavily calcified biopros-
thetic valve with severe leaflet restriction. Doppler exam
revealed a transvalvular mean gradient measuring 16 mm
Hg and a pressure half-time of 391 ms coinciding with
severe bioprosthetic stenosis. Of note, “pressure half-time
seldom exceeds 130 ms across a normally functioning
mitral valve prosthesis” and “a markedly prolonged single
measurement (>200 ms) may be a clue to the presence of
prosthetic valve obstruction.”1
Despite the fact that the
pressure half-time method may not accurately convey
effective valve area in a prosthetic mitral valve, it was cal-
culated to be 0.56 cm2
(Figure 1).2
Further notable intraop-
erative findings consisted of a previously undocumented
large left atrial thrombus and an unidentifiable left atrial
appendage (LAA).
After standard cannulation and initiation of cardiopul-
monary bypass, the left atrium was opened in the intra-atrial
groove. Surgical resection revealed a severely calcified
bioprosthetic valve with thrombus extending over the
hood of a previously oversewn LAA and onto the roof of
the left atrium. Following surgical thrombectomy and the
placement of a mechanical valve, the patient easily sepa-
rated from cardiopulmonary bypass and had an uneventful
postoperative course.
Overall, 86% of bioprosthetic valves placed in the mitral
position maintain their durability over 10 years.3
In this
case, a possible contributing factor toward early calcifica-
tion of the bioprosthetic valve was calcium supplementation
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3. Connors et al 113
Figure 1. Obtained in the mid-esophageal aortic valve long-axis view, this continuous wave Doppler tracing through the stenotic
mitral valve reveals a pressure half-time of 391 ms and a calculated valve area of 0.56 cm2
. Using this diastolic flow velocity profile,
the mean gradient measured 16 mm Hg
Figure 2. A mid-esophageal aortic valve long axis view
showing the large thrombus layering the left atrium
due to surgical hypoparathyroidism. Structural deteriora-
tion, defined as a change in valve function as a result of an
intrinsic abnormality, may cause either stenosis or regur-
gitation. As the primary complication of biologic valves, it
is the foremost reason for reoperation and may occur at any
time after implantation.4,5
Although bioprosthetic valves
have the advantage of not requiring anticoagulation, they
are predisposed to calcification when compared to a mechan-
ical implant. With a history of premature bioprosthetic cal-
cification and concomitant warfarin therapy for PAF, the
patient received a mechanical replacement, which relieved
the stenotic lesion.
Despite a previously oversewn LAA, a short documented
history of paroxysmal atrial fibrillation and a suprathera-
peutic INR at presentation, intraoperative transesophageal
echocardiography revealed a significant left atrial throm-
bus (Figure 2). In all, 90% of left atrial thrombi are found
in the 2 to 4 cm LAA, which has previously been referred
to as “our most lethal attachment.”6
In this case, hemody-
namically significant mitral stenosis coupled with the lack
of mitral regurgitation likely contributed to left atrial stasis
leading to thrombus formation. In addition, incomplete
exclusion of the LAA may also increase thrombotic risk as
it serves to promote stasis in the LAA remnant. While the
Left Atrial Appendage Occlusion Study revealed success-
ful exclusion in only 45% of patients with oversewing of
the LAA, other authors place the success rate closer to 90%
when coupled with mitral valve surgery.6
In our patient,
because of thrombotic layering over the hood of the over-
sewn LAA, it was unclear if the LAA was completely
obliterated during the original surgery.
With the clinical presentation of symptomatic mitral
stenosis, echocardiographic assessment revealed severe
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4. 114 Seminars in Cardiothoracic andVascular Anesthesia 15(3)
bioprosthetic mitral obstruction. Of note, this premature
valve degeneration was associated with calcium supple-
mentation in the setting of secondary hypoparathyroidism.
This case was further complicated by the presence of a
large left atrial thrombus despite a previously oversewn
LAA and supratherapeutic INR. Successful placement of a
mechanical valve in the mitral position served to resolve
the patients symptomatic mitral stenosis, decrease the risk
of premature calcification relative to a bioprosthetic implant
and,incombinationwithcontinuedwarfarintherapy,decrease
the risk of recurrent left atrial thrombosis.
Authors’ Note
Written informed consent has been obtained from this patient.
Declaration of Conflicting Interests
Dr. Weitzel had no conflict of interest in this submission
and played no role in the editorial decision process for this
article.
Funding
The author(s) received no financial support for the research,
authorship, and/or publication of this article.
References
1. Zoghbi WA, Chambers JB, Dumesnil JG, et al. Recommen-
dations for evaluation of prosthetic valves with echocar-
diography and Doppler ultrasound. J Am Soc Echocardiogr.
2009;22:975-1014.
2. Pybus DA. Thrombotic occlusion of a bileaflet, mechanical
mitral valve. Anesth Analg. 2007;105:1567-1568.
3. David TE, Ivanov J, Armstrong S, Feindel CM, Cohen G.
Late results of heart valve replacement with the Hancock II
bioprosthesis. J Thorac Cardiovasc Surg. 2001;121:268-277.
4. Polo ML, Legarra JJ, Vilar M, Cabrera A, Durán D, Pradas G.
Early calcification of a Carpentier-Edwards perimount mitral
valve in an elderly woman. J Thorac Cardiovasc Surg. 2002;
124:1043-1044.
5. Cohn LH, Aranki SF, Rizzo RJ, et al. Decrease in opera-
tive risk of reoperative valve surgery. Ann Thorac Surg.
1993;56:15-20.
6. Healey JS, Crystal E, Lamy A, et al. Left Atrial Appendage
Occlusion Study (LAAOS): results of a randomized con-
trolled pilot study of left atrial appendage occlusion during
coronary bypass surgery in patients at risk for stroke. Am
Heart J. 2005;150:288-293.
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