43. Non-ischemic Mitral Valve Regurgitation- Clinical Scenarios

Jordan P. Bloom, MD, MPH and Serguei Melnitchouk, MD, MPH

Adapted from 1^st edition chapter written by Jennifer M. Worth, MD, and Chittoor B. Sai-Sudhakar, MD

Concept

• Etiology and pathophysiology
• Indications for mitral valve intervention in the setting of primary mitral regurgitation
• Preoperative evaluation
• Mitral valve repair techniques
• Management of complications
• Pearls / Pitfalls

Chief complaint

“A 68 yo woman is referred to you with a 4-month history of shortness of breath after being diagnosed with severe mitral regurgitation by echocardiography.”

Differential

Differentiate primary vs. secondary valvular disease. Primary or organic mitral regurgitation is a result of an intrinsic valve abnormality. These include the entire spectrum of the degenerative mitral valve disease (ranging from fibroelastic deficiency to Barlow’s valve), congenital malformations, inflammatory diseases, bacterial endocarditis, calcification, trauma, and tumors. Secondary or functional mitral regurgitation is due to problems with the heart resulting in secondary annular dilation. The most common etiology is ischemia with subsequent ischemic cardiomyopathy; other causes include dilated cardiomyopathy, hypertrophic obstructive cardiomyopathy, myocardial sarcoidosis, endomyocardial fibrosis, and myocardial tumors. 

History and physical

It’s important to elicit any symptoms of angina or heart failure in addition to comorbid conditions which all affect survival. Focused physical exam including vitals, neurologic exam, heart/lung sounds, peripheral exam including pulses and edema. The holosystolic murmur of MR best heard in the left lateral decubitus position at the apex and radiates to the axilla. If the murmur radiates toward the aortic area the pathology is likely a flail PL; whereas if the murmur radiates toward the spine or axilla, it is likely a flail AL. The murmur of functional MR is variable and has poor correlation between intensity and severity (due to LV dilation, variable volume status, etc.).

Tests

• EKG: look for evidence of previous infarcts, cardiomegaly; may see left atrial (LA) enlargement or atrial fibrillation.
• CXR: may see cardiomegaly, LA enlargement, and/or pulmonary edema.
• Echo: severe MR documented by a vena contracta width of ≥ 0.7 cm, effective regurgitant orifice (ERO) ≥ 0.4 cm², regurgitant volume (RV) ≥ 60 mL, regurgitant fraction (RF) ≥ 50%, and an effective regurgitant orifice/jet area (ERO) > 40% of LA area. 3D echo is a useful modification to enable better visualization of functional and anatomic relationships to help plan operations.  Transesophageal echocardiogram (TEE) gives much clearer images and is typically used to classify the mechanism of valvular dysfunction (Table 39-1) and document the severity (Table 39-2).             It also provides a much better assessment of mitral valve, aortomitral curtain, and/or aortic root involvement in endocarditis cases.

Table 39-1. Carpentier’s Functional Classification of Mitral Valve Dysfunction.

Dysfunction	Leaflet Motion	Common Etiologies
Type I	Normal leaflet motion	Annular dilation due to ICM/DCM, perforation in endocarditis, congenital cleft
Type II	Increased leaflet motion (leaflet prolapse)	Valve prolapse due to FED, myxomatous degeneration, Barlow’s valve, Marfan syndrome, endocarditis, trauma
Type IIIa	Restricted leaflet motion in diastole (restricted opening)	Leaflet thickening due to rheumatic disease, radiation, carcinoid, lupus
Type IIIb	Restricted leaflet motion in systole (restricted closure)	Leaflet tethering due to ICM, DCM

Table 39-2. Mitral regurgitation severity.

	RV	RF	ERO
Mild	< 30 mL	< 30%	< 0.2 cm2
Moderate	30-59 mL	30-49%	0.2-0.39 cm2
Severe	> 60 mL	> 50%	> 0.4 cm2

• MR is commonly graded on a scale of 0-4: 0 = none/trivial; 1 = mild, 2 = moderate, 3 = moderate-to-severe, and 4 = severe
  • Cardiac catheterization: look for evidence of coronary artery disease and dominance. It is important to know whether the patient has a right or left dominant coronary circulation for the rare case of trouble coming off cardiopulmonary bypass and/or lateral/inferior wall hypokinesis. MAC can also typically be seen on LHC.
  • ECG gated CTA: alternative modality (supplanting coronary cath) to screen for coronary artery disease in low-risk patients. Also helpful in cases of MAC to assess proximity of calcium to the left circumflex artery.

Indications for surgical repair

The indications for therapeutic options for MR are summarized below according to the 2014 AHA/ACC guidelines.

Nishimura RA, Otto CM, Bonow RO, Carabello BA, Erwin JP III, Guyton RA, O’Gara PT, Ruiz CE, Skubas NJ, Sorajja P, Sundt TM III, Thomas JD. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;129:2440–2492.

Index scenario (additional information)

“The patient is not diabetic and has shortness of breath with moderate activity. Echo shows vena contracta of 0.6 cm, EF 55-60%, and mild dilation of the LA in the setting of P2 leaflet prolapse. The MR is graded as 3-4+. What are treatment options and how would you proceed?”

Treatment/management

This patient has moderate-to-severe symptomatic primary MR and thus meets criteria for mitral valve intervention (Class I recommendation). Modern options for mitral valve regurgitation include surgical repair or replacement and catheter-based approaches (reserved mostly for high-risk patients) such as the MitraClip or transcatheter mitral valve replacement (TMVR) via transfemoral or transapical approach. Most commonly, mitral valve surgery is performed through either a full sternotomy or a right mini-thoracotomy. Some programs use either total endoscopic or robotic platforms for even smaller incisions.

Mitral valve repair has become the standard of care for such patient and results in the most favorable survival profile. Criteria favoring mitral valve repair include chordal rupture in a limited portion of the posterior leaflet with normal anterior leaflet or a simple prolapse of the posterior leaflet. In addition, ruptured chordae to the anterior leaflet, myxomatous degeneration, or leaflet perforation/chordal rupture from endocarditis.  Valve repair should follow Carpentier’s principles including preservation or restoration of full leaflet motion, creation of a large coaptation surface, and stabilization of the annulus. 

Operative steps for mitral valve exposure via median sternotomy

• Place a large bore IV, arterial line, GETA, PA catheter, Foley catheter.
  • Check intraoperative TEE for mitral anatomy. Confirm the direction and complexity of the jet, the presence of a flail segment or leaflet prolapse. Anteriorly directed jet is due to posterior leaflet prolapse and posteriorly directed jet is due to anterior leaflet prolapse. The TEE gives you a sense of the feasibility for repair. Also consider patient factors and your tolerance for a second pump run if the repair fails. For this you need to consider comorbidities, age, etc.
  • Median sternotomy, pericardial stay sutures, palpate the aorta for calcifications ± epiaortic ultrasound.
  • Heparin (400 mg/kg), aortobicaval cannulation, antegrade and retrograde cardioplegia catheters placed. Initiate CPB once ACT is 480. Administer antegrade cardioplegia to achieve diastolic arrest (while periodically ruling out LV distention).  Cooling to 34 C is sufficient for the majority of cases. Consider cooling to moderate hypothermia (28-32° C) for a better myocardial protection in more complex/prolonged cases. In cases of transseptal approach, dissect and encircle the IVC and SVC while snaring them with tourniquets. The exposure is a matter of choice. The following describes the most common left atriotomy (paraseptal) approach via Sondergaard’s (Waterston’s ) groove:
• Use scissors or cautery to expose the roof of the left atrium along Sondergaard’s groove.  Be careful not to get into the RA.  This step can be done prior to arresting the heart but is easier done while on bypass with the RA decompressed.  After heart is arrested, an incision is made in the middle of the dissected area – away from pulmonary veins while leaving a sufficient rim of LA tissue at the groove for a later closure. LA incision is extended in a curvilinear fashion superiorly and inferiorly to allow placement of retractor blades. Stay away from the pulmonary veins and the right atrium. A flexible pump sucker is placed into the left inferior pulmonary vein to keep the operative field dry. Self-retaining or handheld retractors are used to aid the exposure. 
  • Perform valve analysis and determine pathology:
• Annulus (dilated, calcified – atrial versus ventricular calcification)
• Leaflet tissue (prolapse – which segment?, flail, redundant myxomatous tissue or limited fibroelastic degenerative tissue)
• Chordal attachments (primary – margin, secondary – underside, tertiary – annulus)
• Height of the posterior leaflet (ideal is 2/3 anterior and 1/3 posterior or less than 1.5 cm posterior leaflet).
• Goals – Repair valve if technically feasible, otherwise replace with mechanical valve if less than 60 yo (needs to be explained to the patient preoperatively). Use a bioprosthetic valve in patients > 60 yo, women of childbearing age, or if contraindication to warfarin exists.

Valve repair

• Carpentier’s principles of valve repair include preservation or restoration of full leaflet motion, creation of a large coaptation surface, and stabilization of the annulus.

• A ring or a band annuloplasty are considered necessary adjuncts to reinforce most repair techniques. Some surgeons place the annuloplasty sutures first to aid the exposure. Start with posteromedial trigone and work counterclockwise using non-pledgeted braided horizontal mattress sutures. Make sure you get the fibrous trigones (appear as “dimples” and are one stitch above the corresponding commissures). In case an annuloplasty band is used instead of a complete ring (a band and a complete ring are equally effective for repair of primary mitral regurgitation), one would not place sutures between the trigones along the base of the anterior leaflet, while placing decent anchoring stitches in the trigones themselves and travelling from one trigone to another.
  • Neighboring structures: avoid deep (and outside the annulus) stitches in the area of posteromedial commissure/right trigone (conduction tissue); avoid deep stitches along the base of the anterior leaflet while travelling from the right trigone to the left (aortic valve); avoid deep bites near the base of P1 scallop and instead angle the needle toward the ventricle (away from the atrium) to avoid injuring circumflex artery. One can also injure the coronary sinus with a deep retraction stitch outside the annulus of the P3 scallop, while trying to obtain a better visualization of the latter. 
  • Mitral valve prolapse is a spectrum of disease. Therefore, in fibroelastic deficiency, where there is paucity of tissue, one should either use neochords or do a very limited triangular resection. In Barlow’s valve, where there is excess tissue in almost all scallops, one needs to perform quadrangular resection with a sliding plasty to remove excess tissue from the posterior leaflet. When there is excess tissue in height and width in one of the scallops (e.g. myxomatous degeneration of P2), one either performs a limited quadrangular resection with a sliding plasty or a triangular resection with reduction of leaflet height (“butterfly technique”). When performing resectional techniques, it often helps to place a silk suture around the healthy chordae that flank a diseased segment and resect only the diseased segment. Cut edges of leaflets are then reapproximated using interrupted or running non-absorbable suture.
  • When performing neochordal repair technique (either for anterior or posterior leaflet prolapse), one places a CV-4 (or CV-5) PTFE suture either as a figure of eight or as a pledgeted horizontal mattress stitch through the head of a papillary muscle. Both suture ends are then brought twice through the free edge of the prolapsing segment (each time from the ventricular side to atrial side). It is much easier to place the neochords before the annuloplasty ring is tied. Once the ring is tied, the left ventricle gets insufflated with saline and the length of the neochords is adjusted so that there is a tight seal between the coapting leaflets without any residual leaflet prolapse. Then, the sutures are carefully tied (without excessive tension) in order to avoid inadvertent overcorrection with subsequent result of leaflet tethering. Most frequently one needs to place two (or even three, four) sets of PTFE sutures (using both papillary muscles) in order to reliably repair a wide P2 or A2 prolapse or a bileaflet prolapse. Only in an isolated focal prolapse one set of neochords might be sufficient.
  • Chordal transfer can be used to repair anterior leaflet prolapse as well. In this case, a portion of posterior leaflet is excised and transferred (“flipped over”) along with its primary chords to the prolapsing segment of the anterior leaflet. Obviously, one then needs to reconstruct the posterior leaflet in a standard fashion and that is the major drawback of this repair technique. Secondary chord transfer can be used as an adjunct technique to strengthen the anterior leaflet edge in addition to the neochords. In this technique, a strong secondary chord is cut from the undersurface of AL and transferred to the leaflet edge, where it is affixed with non-absorbable  suture. In addition to strengthening the neochordal repair it also helps to correctly estimate the desired neochordal length.
  • Commissuroplasty is frequently employed to repair commissural prolapse. In this technique both commissural edges are sutured together with either a running suture or with a series of imbricating horizontal mattress sutures (preferred), thus placing the prolapsing tissue below the coaptation plane. One is judicious about the extent of closure to avoid creating mitral stenosis and is therefore cognizant to choose the largest acceptable annuloplasty ring in such cases.
  • In cases of leaflet thickening or retraction (such as in IIIa), one sometimes needs to extend the height of either anterior or posterior leaflet. For this a glutaraldehyde-treated autologous pericardium is tailored in a semilunar (posterior leaflet) or an ovoid (anterior leaflet) shape. The leaflet is detached at approximately a 3-5 mm distance from the annulus and incision has to be extended from one commissure to another in order to achieve effective height extension and non-restricted leaflet motion.
  • Size the annuloplasty ring (or band) to match the height of the anterior mitral leaflet (not the intertrigonal distance) and upsize if possible while performing insufflation of the left ventricle with saline solution (saline test). Band and ring sizes typically range from 26 to 40mm. A larger ring/band helps prevent systolic anterior motion (SAM) and has lower transmitral gradients due to a larger mitral valve area (MVA). Sew the band and tie the sutures. Some perform a final saline test at this point and do an “ink test” along the coaptation line in order to assess whether the ink line is not too high on the anterior leaflet (ideally should be at the transition between the clear and rough zones of the anterior leaflet to avoid SAM) and confirm presence of sufficient  coaptation depth along the posterior leaflet.   
  • After deairing and closing the left atrium, remove cross clamp and wean from the CPB. Assess the valve with TEE and have a low threshold to convert a repair to a replacement if left with 2-3+ MR. Be aggressive with re-repair even in the setting of a mild MR in younger patients. Use judgement, but mild MR in a frail elderly patient is acceptable. Incidentally, the older the patient and the more the comorbidities, the more you might consider mitral valve replacement with a tissue valve, especially in the setting of a complex valve pathology.
  • The usual checklist after a mitral valve repair involves checking:
• 6-lead ECG (rhythm, conduction abnormalities, evidence of ischemia)
• Residual MR (trivial or mild (in some cases) are acceptable)
• Transmitral gradient (should be less than 5 mmHg)
• Rule out presence of SAM
• Rule out lateral/inferior wall hypokinesis
• Rule out new eccentric AR
• Assess presence of air and deair accordingly via aortic root

Valve replacement

• Detach the anterior leaflet approximately 3 mm from its base from commissure to commissure. Prepare two leaflet edge segments for chordal sparing valve replacement by dividing the anterior leaflet in the middle and resecting excess leaflet tissue while leaving strong primary chords along with the corresponding leaflet edge segments. Those two segments will be anchored by valve sutures to the corresponding commissures on either side. Attempt to preserve the entire posterior leaflet with its chords to mitigate risk of AV groove disruption and resect only excess or prolapsing tissue as needed. One is to avoid leaving too much chordal tissue behind, especially in the setting of small left ventricles. Some small series suggest that excess chordal tissue might contribute to higher incidence of tissue valve thrombosis due to increased flow turbulence. On the other side, judicious chordal sparing technique is associated with a better postoperative long-term left ventricular function and remodeling.
  • If calcium is encountered in the subannular space, debride only if necessary, for the valve to lie flat and well opposed to the annulus or to facilitate suture placement (“respectfully resect”). Atrial decalcification can be done safely but the more you debride the ventricular calcification the greater the risk of AV groove disruption or circumflex injury. If you debride the calcification extensively including the ventricular calcium, you need to sew a pericardial patch (autologous or bovine) that saddles the annulus and covers the entire area of decalcification. In terms of annular suture placement, both everting (pledgets on the atrial side) and non-everting (pledgets on the ventricular side) horizontal mattress suture placement techniques are generally acceptable for regular mitral valve replacement cases. However, in the setting of decalcification or mitral annular calcium (MAC), a non-everting technique (pledgets are on the ventricular side) is strongly advised in order to further mitigate AV groove disruption. 
  • Bioprosthetic valves should be oriented with the post well out of the outflow tract. To accomplish that, two posts face the trigones and the third post divides posterior annulus in the middle. Mechanical valves are usually implanted in an anti-anatomic position in which the hinge lines are orthogonal to the native mitral commissures. Alternatively, a mechanical valve can be implanted in anatomic position in which the hinge lines are parallel to the native mitral commissures. Some studies using vector flow mapping to assess hydraulics of the left atrium found the formation of blood flow in the form of vortex, where both leaflets of a prosthetic valve positioned in an anti-anatomic orientation would receive equal initial opening force due to symmetric orientation of the leaflets relative to the atrial vortex. In contrast, in anatomic position the posterior leaflet often demonstrates subtle delayed opening and early closure, a phenomenon also known as “lazy” leaflet.  Also, of importance is to assess the leaflet clearance and strive for absolutely no interference from the subvalvular apparatus. Occasionally, if despite all measures one of the leaflets is immobile on TEE after coming off the CPB, one needs to rearrest the heart and turn the valve 45 degrees to either side. 
  • Close atriotomy with a running prolene suture, irrigate, deair, and wean from CPB.

Potential questions/alternative scenarios

“A 60 yo woman presents for follow up of her known mitral regurgitation. She has minimal symptoms which in no way disrupt her activities of daily living. She is very active. When would you offer an asymptomatic patient an MVR.”

According to the guidelines, patients with chronic severe MR (3-4+) should be offered surgery if the patient experiences mild-moderate LV dysfunction with an EF less than 60%, moderate PHTN (PAP > 50 mmHg at rest), new onset atrial fibrillation, or an end systolic ventricular dimension (ESD) greater than or equal to 40 mm. Asymptomatic patients with preserved LVEF and > 95% likelihood of successful repair may be offered surgery for chronic severe MR.

“A 56-year-old female patient with a heart murmur presented to the ED with worsening dyspnea and hemoptysis. Four days prior she endorsed an intense workout during which she experienced severe precordial chest pain.  On presentation she was tachycardic, with elevated JVP and bilateral RALS.  There was a grade IV pansystolic murmur best heard at the apex.  A CXR revealed bilateral pleural effusions.  What is the most likely diagnosis and how would you manage?”

This is a classic scenario for exercise-induced acute chordal rupture resulting in severe MR and subsequent heart failure.  Patients with MVP are at an increased risk.  Other diseases such as rheumatic heart disease and infectious diseases such as endocarditis can also cause chordal rupture.  Blunt chest trauma is another rare cause of this problem.  Patients should be taken to the operating room for urgent mitral valve repair to avoid long term consequences of acute MR in a non-accommodated LA. Acute chordal rupture has degenerative etiology and needs to be differentiated from the papillary muscle rupture due to ischemia as the management differs.

“A 59-year-old male was admitted with an acute onset of shortness of breath. Physical exam reveals bilateral rales and a systolic murmur. Chest X-ray shows right lung opacification in the setting of leukocytosis. Echocardiography shows severe mitral regurgitation (MR) in the setting of a flail PL.”

As in the previous scenario, this is a case of an acute mitral regurgitation due to an acute chordal rupture and it requires an urgent corrective mitral valve surgery. Patients who present this way are commonly misdiagnosed as having “atypical pneumonia” and are treated frequently with antibiotics. They invariably decompensate quickly if the MR is not addressed immediately and have high risk of mortality.  Almost all cases of mitral disease-associated unilateral pulmonary edema is right sided and thought to be due to flow reversal into the pulmonary veins during systole. 

“What are the different approaches to expose the mitral valve and when would each be considered?”

Table 39-4. Mitral valve exposure

Standard Approach
Left Atriotomy (paraseptal)	Most common approach to MV Via Sondergaard’s (Waterston’s) groove Incision of choice for mini-thoracotomy and robotic platforms
Transseptal Approaches
Vertical transseptal	Incision via fossa ovalis Feasible with a large LA in the setting of a chronic MV pathology Reduces risk of PPM, easier closure
Extended superior transseptal (Guiraudon)	Vertical transseptal incision is extended superiorly onto the dome of the left atrium Risk of damaging the SA nodal artery (higher risk of PPM) Generally, a better exposure for a deep chest anatomy / wide AP diameter Approach of choice in the setting of previous AVR or aortic root replacement Can be easily extended and connected with an aortotomy incision for a “Commando” operation (e.g. endocarditis, radiation case)
Horizontal transseptal (Dubost)	Very uncommon Can be considered in the setting of a hostile anatomy between the aortic root and LA dome (e.g. presence of calcified aortic homograft, etc) Difficult closure, risk of narrowing right superior pulmonary vein, risk of transseptal incision progressing and tearing AV node area, high risk of PPM
Alternative Approaches
Transaortic	Aortotomy is extended onto the dome of the left atrium Useful in endocarditis cases when both aortic and mitral valves need to be replaced (transaortic Commando) Exposure can be challenging; in which case the incision can be connected to the extended transseptal incision
Left atrial appendage	Very uncommon Requires left thoracotomy Alternative approach after multiple previous re-operations
Transventricular	Can be utilized if entering the LV for another reason (e.g ventricular aneurysmectomy or LVAD placement)

“Your patient being evaluated for a mitral repair had a previous AVR complicated by a wound infection and mediastinitis requiring flap closure.”

Right anterolateral thoracotomy approach – 4th intercostal space centered in the anterior axillary line. Femoral venous and arterial cannulation. Be familiar with alternative strategies to arrest the heart since you may not be able to clamp and deliver antegrade so easily in this case. Options include fibrillatory arrest under moderate hypothermia or endoballoon (both require competent aortic valve).

“Anesthesia gives the patient nipride to make room for more volume when coming off the pump. The patient becomes hypotensive and 3+ MR is noted with encroachment of the anterior leaflet onto the LVOT. What is the treatment?”

This patient has systolic anterior motion (SAM) of the mitral valve which was accentuated by the increased ventricular systolic contraction in the setting of an underfilled ventricle. The treatment of choice here is to wait while the volume rolls in. May also consider adding a beta blocker to reduce the vigor of the systolic contractions once the volume is optimized. Inotropic support and/or reduced afterload will make things worse.

“Describe SAM and options for correcting it after an attempted mitral repair.”

The line of coaptation after a reduction annuloplasty and leaflet resection/repair typically gets displaced just a bit more anterior (towards the LVOT) than it did before. The anterior leaflet can obstruct the LVOT during systole creating a gradient. As the anterior leaflet gets sucked into the LVOT during systole (Venturi effect), the posterior leaflet prolapses towards the atrium causing an anteriorly directed jet. Thus, the two main worrisome components of SAM are regurgitation and high LVOT gradient. If the posterior leaflet is left > 1.5 cm in height after repair the risk for SAM is greater. If the patient has a small hyperdynamic ventricle the risk for SAM is greater. If the ring is undersized too much, then the risk of SAM is also greater because the line of coaptation bulges anteriorly. First ensure that you are not simply underfilled as described in the prior scenario. Otherwise, treatment strategies aim to reduce the posterior leaflet height if it is clear that that is the culprit. Folding valvuloplasty of the edge of the posterior leaflet with interrupted horizontal pledgeted sutures, changing a triangular resection into a quadrangular with sliding annuloplasty, and placement of a larger ring are all options for reducing the posterior leaflet height. A more aggressive maneuver is to replace the valve. Another simple fix in a frail high-risk patient that may not tolerate a second pump run is an Alfieri stitch.

“What are the pre- and intra-operative SAM risk factors?”

• Tall posterior leaflet (>15mm)
• AL:PL ratio £ 1.3
• Aorto-Mitral Plane Angle < 120 deg
• Coapt – Septum Distance < 25mm
• Interventricular septum (IVS) thickness > 15mm
• Small and hyperkinetic LV
• Anterior displacement of papillary muscles
• Small prosthetic ring

“After a mitral valve replacement, a significant amount of bright red blood is seen welling up behind the heart once the cross clamp is released!”

Atrioventricular dissociation after mitral valve replacement. Often occurs after completion of CPB or a few hours after procedure. Patients have massive intrapericardial hemorrhage which can be a lethal event. Rupture occurs in the LV near the AV groove posteriorly. Tends to occur more in women with small LVs. Generally considered to be a technical error from a) too much traction on the annulus during excision of the valve or insertion of prosthesis; b) tearing of the annulus after the new valve is in place when the heart is lifted manually; c) penetration of stitches in the posterior left AV groove; d) perforation from papillary muscle excision; e) perforation of AV groove during calcium debridement (especially with ventricular calcium). Go back on CPB and re-arrest. Re-open the LA, remove the prosthesis and inspect the ventricle. An appropriately sized pericardial patch is secured over the area of perforation with a running prolene suture and interrupted pledgeted sutures as needed. The valve is reimplanted and the operation is completed as previously described.  If the initial operation was a mitral valve repair, the valve must be replaced if there is an AV groove disruption. This is necessary because the PL tissue is now used to buttress the patch repair and reduce tension on the suture line of the patch repair by providing additional chordal support beyond the repair.

“ST changes are noted along the lateral leads and the patient becomes hypotensive requiring high dose epinephrine and norepinephrine. What has happened?”

The differential may include postcardiotomy syndrome with cardiogenic shock from reperfusion or poor protection. However, the most likely culprit in the setting of a valve replacement is damage to the coronary especially with the isolated lead changes. Go back on, harvest a segment of vein, arrest and bypass to a distal OM.

Note that a valve causing excessive traction on the circumflex can lead to delayed myocardial ischemia and even LV rupture secondary to erosion of the strut through an infarcted LV free wall. This is seen most often in women with a small LV or when the LV is weakened after an infarct. Special care needs to be taken to ensure the safety of the circumflex artery and if any question is raised, a marginal branch should be bypassed using a SVG prior to coming off cardiopulmonary bypass.

“After opening the left atrium, there is much more blood than is expected despite a floppy sucker in the RSPV.  You cannot see anything, what are the possible explanations?”

First, check that the aortic cross clamp is completely around the aorta and tight enough to occlude flow.  Next, explore the septum for an ASD.  This is typically able to be accomplished via the left atrium although sometimes to repair may require a right atrial incision.

Pearls/pitfalls

• Know the indications for mitral valve surgery.
  • Know the different exposures for the mitral valve and when you would choose one over the other.
  • Know the major complications of the procedure – circumflex injury, AV disruption, aortic regurgitation.
  • Recognize SAM and its treatment (medical – volume, betablocker; surgical – posterior leaflet height reduction, upsizing the band/ring size).
  • Know how to deal with a calcified mitral annulus.

Suggested readings

• Kouchoukos NT and Kirklin JW. Kirklin/Barratt-Boyes Cardiac Surgery: Morphology, Diagnostic Criteria, Natural History, Techniques, Results, and Indications. Philadelphia, Pa: Churchill Livingstone, 2003.
  • Yuh, DD, Vricella LA and Baumgartner WA.The Johns Hopkins Manual of Cardiothoracic Surgery. New York: McGraw-Hill Medical Pub, 2007.
  • Carpentier, A., Adams, D. and Filsoufi, F., 2010. Carpentier’s Reconstructive Valve Surgery. Maryland Heights, Mo.: Saunders/Elsevier.