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\begin{document}

\title{Basal cuspal tear of a porcine bioprosthetic mitral valve causing
massive mitral regurgitation}



\author[1]{Muhammed  Tamim}%
\author[1]{CHRISTOS ALEXIOU}%
\author[1]{Yaser AlKady}%
\author[1]{Mohsen Mahmoud}%
\author[1]{Fatima Qaddoura}%
\affil[1]{King Fahd Military Medical Complex}%


\vspace{-1em}



  
  \date{May 21, 2024}


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\selectlanguage{english}
\begin{abstract}
Although porcine mitral bioprostheses provide predictably good long-term
outcomes, unexpected leaflet tears leading to abrupt haemodynamic
changes may occur. We report on a patient who presented with acute
dyspnea due to cuspal tear of a porcine bioprosthetic mitral valve
causing severe mitral regurgitation, her condition was subsequently
complicated by systemic infection, probably pneumonia, and was
successfully managed with urgent redo-mitral valve replacement.%
\end{abstract}%



\sloppy


\textbf{Key Words}

Cardiovascular pathology

Valve repair/replacement

\textbf{INTRODUCTION}

Appropriate follow-up after surgical implantation of bioprostheses
ensures the timely detection of dysfunctional heart valves and their
replacement in a safe manner (1,2). Nonetheless, catastrophic structural
valve deterioration can occur (1-5) early or late postoperatively (6.7).
We describe the clinical presentation, management and outcome of a
patient who suffered cuspal tear of a bioprosthetic mitral valve four
years post valve

implantation, and discuss her case in context with the pre-existing
relevant literature.

\textbf{CASE HISTORY}

A 53-year old female patient was admitted in a peripheral hospital with
severe, acute onset dyspnea and orthopnea. Her past medical history
included bioprosthetic aortic valve replacement (AVR) and mitral valve
replacement (MVR) 4 years ago. Two hours later, she required intubation
and mechanical ventilation, and transthoracic ECHO showed significant
MR. Two days later, she developed high grade fever (39C), accompanied by
radiological changes compatible with right lower lobe pneumonia, and a
sharp rise in serum inflammatory markers. Multiple blood cultures, skin
and nasopharyngeal swabs were taken, and she was commenced on i.v.
antibiotics (Tamiflu, Tazocin, Azithromycin). All cultures returned
negative including those for MERS-COV and H1N1. Meanwhile, she
grew\emph{Methicillin Resistant Staphylococcus Aureus} in a
nasopharyngeal swab and the antibiotic treatment was changed to i.v.
Meropenem, Vancomycin and Levofloxacin. Transesophageal echo (TEE)
showed severe MR and malfunction of the bioprosthetic MV and was
referred to our center.

On admission to the intensive care unit, she was mechanically
ventilated, highly pyrexial, on high doses of noradrenaline. Repeat TTE
showed a flail mitral valve leaflet and severe MR (Figures 1,2, 2D TEE),
(Figures 3, 3D TEE), dilated left atrium (LA), elevated systolic
pulmonary artery pressure (75mmHg), moderate tricuspid regurgitation
(TR), accelerated flow across the aortic bioprosthesis (mean gradient
32mmHg) and preserved bi-ventricular function. Computed tomography of
the chest and abdomen showed right lower lobe consolidation consistent
with pneumonia. She continued to run high fever and to require high
doses of vasopressors and inotropes in order to maintain adequate blood
pressure and urine output. Considering persisting fever, the
unsatisfactory response to antibiotic therapy, severe haemodynamic
compromise caused by the mechanical dysfunction of the prosthetic MV and
the risk for irreversible multiorgan failure, a decision was taken to
proceed with urgent surgical intervention seven days after her admission
to our hospital.

A standard redo-MVR and De Vega TV annuloplasty were performed through a
median re-sternotomy, utilizing cardiopulmonary bypass (aortic and
bicaval cannulation), antegrade delivery of Del Nido cardioplegia and a
right atrial-transeptal route to access LA and the MV. On inspection,
one of the leaflets of the prosthetic MV was detached across its base
from the frame of the valve, almost from commissure to commissure
(Figure 4). The valve otherwise appeared normal without vegetations,
thrombus or signs of valve dehiscence. The bioprosthesis was excised and
after thorough tissue debridement and washing with normal saline, a
mechanical valve (27mm On-XCryoLife, Inc. NW, U.S.A) was implanted. The
LA appendage was obliterated with continuous suture, the interatrial
septum closed, and the operation completed in the standard manner.
Intraoperative TEE showed moderate biventricular dysfunction, well
seating and normally functioning prosthetic MV without paravalvular
leak, and mild TR.

Six days after surgery, the inotropes were stopped, the patient became
afebrile and was extubated. Thereafter, she made steady progress
becoming fully ambulant; Warfarin was commenced aiming for an INR of
2.5-3. Culture of the explanted valve was negative as were the tissues
and fluids taken at operation. The patient was eventually transferred to
the referring hospital three weeks after her operation for convalescence
and completion of her antibiotic therapy. Pre-discharge ECHO showed
well-functioning valves, mild TR, and mildly impaired bi-ventricular
function.



\textbf{DISCUSSION}

Bioprosthetic valves have good durability and a predictable mode of
failure, with gradual degeneration of the leaflet tissue being the norm
(1-3). As a result, when a re-operation is required, is usually done in
a controlled and safe manner (1-3). Nevertheless, some patients do
experience sudden valve dysfunction due to acute structural valve
deterioration, needing urgent attention (1,2,3,6,7).

In a cohort of 836 patients who had a porcine bioprosthetic valve
replacement, 28 required a re-operation with 18 of them having a leaflet
tear of the explanted valve. Of these 18 patients, 12 had a previous MVR
and 6 had AVR (3). Thus, the proportion of bioprosthetic valve leaflet
tear leading to a re-operation was 2.1.\% (3). Cusp rupture or
detachment in a mitral bioprosthesis may cause massive MR with serious
consequences (3-7). Amongst the 12 patients who had a leaflet tear in a
mitral bioprosthesis in Pomar's series, 6 presented in NYHA III and 6 in
NYHA IV (3).

The initial diagnosis in our patient was cardiogenic pulmonary oedema,
which suggests that the cuspal tear of the bioprosthesis and the ensuing
massive MR was

the primary event. Subsequent clinical, radiological, laboratory and
echocardiographical findings made right lobar pneumonia and/or infective
endocarditis (IE) a likely diagnosis, even though serial blood cultures
were negative. It is well known that approximately 1/3 of patients with
IE have sterile cultures (8). In either case, considering the major
hemodynamic burden caused by the massive MR, urgent surgical
intervention was in our patient imperative (8). Notably, all 6 patients
who had cuspal tear of a bioprosthetic MV went on to have redo MVR in
the elegant study by Pomar (3).

Single or multiple cuspal tears, leaflet perforations, free-edge tears
and basal tears have all been described with the later (also seen in our
patient) being the commonest (3-7). Some torn leaflets are calcified
whereas in others calcification is visible only under light microscopy
(3). In our patient, leaflet tear occurred at the base across its
attachment onto the frame of the prosthetic valve (Figure 4) bearing no
calcium, vegetations or other sign suggestive of infection, and valve
culture was negative. These implies that the detachment of leaflet from
the frame of the valve was a purely mechanical event (9).

Leaflet detachment occurred 4 years after surgery in our patient, which
is in keeping with an average time for cuspal tears of around 4-6 years
quoted by Pomar (3). However, following implantation of a mitral
bioprosthesis, Miura (6) reported a cusp detachment occurring only 10
months after surgery and Ha et al (7) 12 years after surgery.

\textbf{CONCLUSIONS}

Although porcine MV bioprostheses provide predictably good long-term
outcomes, unexpected cusp tears leading to abrupt haemodynamic changes
with disastrous consequences may occur. This reminds us of the need for
meticulous clinical and echocardiographical follow-up of these patients.

\textbf{REFERENCES}

\begin{enumerate}
\tightlist
\item
  Malvindi P, Mastro F, Kowalewski M et al. Durability of Mitral Valve
  Bioprostheses: A Meta-Analysis of Long-Term Follow-up Studies.
  ~\emph{Ann Thorac Surg. 2020;109(2):603-611.}
\item
  Grunkemeier G, Furnary A, Wu Y, Wang L, Starr A. Durability of
  pericardial versus porcine bioprosthetic heart valves. \emph{J Thorac
  Cardiovasc Surg. 2010;144(6):1381-6.}
\item
  Pomar L, Bosch X, Chaitman B, Pelletier C, Grondin C. Late Tears in
  Leaflets of Porcine Bioprostheses in Adults. \emph{Ann Thorac Surg
  1983;37(1):78-83.}
\item
  Gao, G., Wu, Y., Grunkemeier, G.L., Furnary, A.P., and Starr,
  A.~Durability of pericardial versus porcine aortic valves.~\emph{J Am
  Coll Cardiol} .~2004;~44:~384--388.
\item
  Cipriano P, Billingham M, Oyer P, et al: Calcification of porcine
  prosthetic heart valves: a radiographic and light microscopic
  study.\emph{Circulation 66:1100, 1982.}
\item
  Miura T, Hazama S, Iwasaki K, Izumi K, Matsukuma S, Eishi K. A Rapid
  Structural Degeneration of a Porcine Mitral Valve. \emph{Ann Thorac
  Surg 2012;93:e113--4.}
\item
  Ha JW, Chang BC, Chung N, Cho SH. Images in cardiology. Acute severe
  mitral regurgitation due to unusual detachment of bioprosthetic valve
  leaflet.~\emph{Clin Cardiol} . 2000;23(3):213.
\item
  Alexiou C, Langley SM, Stafford H, Lowes AJ, Livesey SA, Monro JL.
  Surgery for active culture-positive endocarditis: Determinants of
  early and late outcome. \emph{The Annals of Thoracic Surgery
  2000;69:1448-1454}
\item
  Koziarz A, Makhdoum A, Butany J, Ouzounian M, Chung J. Modes of
  bioprosthetic valve failure: a narrative review. \emph{Current Opinion
  in Cardiology. 2020 Mar;35(2):123-132.}
\end{enumerate}

\textbf{Figure Legends}

\emph{Figure 1}\textbf{.} Two-dimensional transesophageal ECHO showing
flail leaflet of the bioprosthetic mitral valve.

\emph{Figure 2.} Doppler 2D transesophageal ECHO showing a large mitral
regurgitant jet.

\emph{\textbf{Figure 3}.} Three-dimensional color Doppler
transesophageal ECHO showing a large mitral regurgitant get.

\emph{\textbf{Figure 4}.} Explanted mitral valve bioprosthesis basal
cusp tear (blue arrow) almost from commissure to commissure.

\textbf{Hosted file}

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