<div>Technical tips for Reducing the Risk of Atrioventricular Disruption
Following Mitral Valve Replacement</div><div>M.Marzban MD and P.Benharash MD</div><div>Mehrab Marzban, MD. Peyman Benharash,MD</div><div>Cardiovascular Outcomes Research Laboratories, Division of Cardiac
Surgery, David Geffen School of Medicine at UCLA, Los Angeles,
California</div><div>Corresponding author: Mehrab Marzban,MD</div><div>Email:MMarzban@mednet.ucla.edu</div><div>10833 Le Conte Ave.62-249 CHS</div><div>Los Angeles, CA 90095</div><div>Abstract</div><div>This report describes the effective measures in order to prevent the
devastating complication of AV groove disruption following mitral valve
replacement.</div><div>Ethics committee approval, consent statement and clinical trial
registration are not applicable for our study.</div><div>Introduction</div><div>Rupture of the Atrioventricular (AV) groove or in a broader sense, left
ventricular rupture is a n infrequent but often fatal complication of
mitral valve replacement. Treasure and colleagues were the first to
define this entity in 1973 in 7 patients. (1) In 1980, Cobb et al
described the complication as “transverse midventricular disruption.
“The authors also pointed out that a false aneurysm could be the end
result of an incomplete rupture. Although AV groove rupture was reported
in up to 14% of cases in the early years of valve replacement, refined
surgical techniques and lower profile prostheses have reduced its
incidence to 0.5-2% in modern series (2).</div><div>While the exact mechanism responsible for this complication was
initially unclear, several risk factors including redo operations,
severe annular calcification, advanced age, hemodialysis dependence, and
resection of posterior leaflet and apparatus, appear to increase the
likelihood of AV groove disruption. Preexisting intrinsic myocardial
disease, especially ischemia, rheumatic myocarditis, and infectious
processes have also been implicated. (3) Rupture is most commonly noted
in the operating room or in the early postoperative period and may be
often preceded by a period of systemic hypertension. There are several
reports of late presentation as a pseudo aneurysm of the left ventricle
or delayed rupture in the literature. (5) notwithstanding the favorable
outcomes of few investigators such as Tirone E. David (6), the fatality
of this complication appears to be in excess of 75%. (7). If rupture
occurs outside of the operating room, the chances of successful recovery
are negligible. Thus, every attempt should be made to prevent rupture
from happening. Below, we provide several technical considerations that,
in our experience, have reduced the risk of AV groove disruption.</div><div>Technique:</div><div>Exposure:</div><div>At first, it is essential to identify the high-risk patient based on the
preoperative evaluation. Every patient who has an MVR is a potential
candidate for AV groove complication and every effort should be made to
avoid it, but there is some extra caution which is required in high-risk
groups.</div><div>Good exposure</div><div>good exposure of the mitral valve is of paramount importance to avoid
this complication especially in patients who are obese or have barrel
chest when the LA is small and also in redo surgery. Pericardial
adhesion from the previous operation or rheumatic pancarditis may limit
heart mobility, in this situation, exposing the mitral valve, excising
the degenerated valve, and putting the annular sutures require excessive
traction on the annulus that may lead to subtle or obvious damage to the
ventricular wall. As a result, it is advisable to mobilize the heart
completely from pericardial adhesion. On the other hand, based on the
surgeon’s experience, a proper approach like the trans-septal approach
may be preferred to address the mitral valve.</div><div>.</div><div>Chordal sparing</div><div>Preservation of posterior leaflet and apparatus: Excision of posterior
leaflet and subvalvular apparatus has been suggested as a major
contributing factor for AV groove damage. (8) Thus it is prudent to
preserve the annulo-papillary continuity as much as possible. In some
occasions, due to severe mitral annular calcification, it is inevitable
to resect the posterior leaflet, even in this situation the papillary
muscles should be reattached to the corresponding posterior annulus
either directly by annular sutures or using artificial chordae. This
surgical tip leads to less impairment of left ventricular function and
minimizing the risk of ventricular rupture There are different methods
for annular decalcification based on the calcification severity and
extension, furthermore, the surgeon’s experience has a definitive role.
It can be a piecemeal or en bloc resection associated with annular
reconstruction using autologous or bovine pericardium. Either technique
needs a meticulous dissection, overzealous decalcification should be
avoided.</div><div>Undersizing the prosthesis</div><div>Another important measure is undersizing the prosthesis when the patient
is assumed to be at high risk for AV groove disruption. The oversized
prosthesis has been mentioned as a risk factor for the dreaded
complication of AV groove rupture (9) but, we put our step beyond that,
our recommendation is to undersizing the prosthesis to reduce the
pressure of the prosthesis cuff on the muscle fibers of the AV groove.</div><div>Interrupted pledgetted sutures</div><div>Despite several reports on the safety of continuous suture technique in
mitral valve replacement, we believe that continuous suturing has
potentially more risk of damage to the annulus due to the excessive
traction which is needed for suture placement especially if the exposure
is not optimal. Interrupted sutures provide more secure and reinforced
sutures in severe annular calcification.</div><div>Avoidance of inotrope and volume overload</div><div>Forceful contraction of the left ventricle against the rigid cuff of the
valve prosthesis has been implicated in the pathogenesis of AV groove
disruption following MVR. Most patients after MVR do not require
inotropic support and can be weaned from CPB without difficulty.
Unnecessary use of inotropes should be abandoned. Volume overload and
the chamber distention may contribute to muscle fiber separation in AV
groove and should be avoided.</div><div>Avoidance of heart massage or tapping on the heart for desiring</div><div>There are different methods to deair the heart chambers before the
termination of CPB. Some surgeons used to fill the heart while resuming
the ventilation and squeezing the heart whereas it has the potential to
damage the heart and should be discouraged after mitral valve
replacement.</div><div>Comment</div><div>Following these simple measures in 437 patients with mitral valve
replacement, luckily we did not encounter this dreaded complication.</div><div>References</div><div>1.Treasure R.L.,Rainer W.G.,Strevey T.E.,Sadler T.R.</div><div>Intraoperative left ventricular rupture associated with mitral valve
replacement.</div><div>Chest. 1974; 66: 511-514</div><div>2. Cobb BW, Hatcher CR, Craver JM, Jones EL, Sewell CW:</div><div>Transverse midventricular disruption after mitral valve replacement.</div><div>Am Heurt J 99, 33-50 (1980</div><div>3. Spencer FC, Galloway AC, Colvin SB. A</div><div>clinical evaluation of the hypothesis that rupture of the left ventricle
following mitral valve replacement can be prevented by preservation of
the chordae of the mural leaflet.</div><div>Ann Surg. 1985;202(6):673–80.</div><div>4. Hosono M, Shibata T, Sasaki Y, et al. Left ventricular rupture after
mitral valve replacement: risk factor analysis and outcome of
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Rausch, Cláudio Léo Gelape</div><div>Late atrioventricular groove disruption presenting 7 years after mitral
valve replacement: a case report</div><div>European Heart Journal - Case Reports, Volume 4, Issue 3, June 2020,
Pages 1–5,</div><div>6. Tirone E. David, MD. Left ventricular rupture after mitral valve
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an elderly patient</div><div>J Cardiothorac Surg 9, 28 (2014)</div><div>9.Makoto Kamada 1, Kenji Ohsaka, Susumu Nagamine, Hidemitsu Kakihata</div><div>Left ventricular rupture following mitral valve replacement due to
oversize prosthesis</div><div>Jpn J Thorac Cardiovasc Surg 2004 Dec;52(12):589-91.</div><div>10. Dark JH, Bain WH. Rupture of posterior wall of left ventricle after
mitral valve replacement. Thorax. 1984;39(12):905–11</div>