49. Combined Aortic and Mitral Valve Disease- Clinical Scenarios

Travis Abicht, MD, and Edwin McGee, MD

Adapted from 1st edition chapter written by Alejandro E. Murillo-Berlioz, MD, and Carmelo A. Milano, MD

Concept

  • Indications for combined valve operation
  • Preoperative considerations
  • Intraoperative considerations
    • Sequence of operation
    • Myocardial protection
    • Valve choices
  • Pitfalls
  • Postoperative issues


Chief complaint

“A 75-year-old man is referred to your office after being diagnosed with a murmur heard by his primary care physician. He had a history of a febrile illness when he was younger. He has been increasingly lightheaded and short of breath with exertion to the point that he cannot walk a full block.”


Differential

Given the patient’s age, aortic stenosis is a concern. Other conditions that should be considered include mitral valve disease. Certainly, the patient could have a combination of aortic and mitral valve disease. Endocarditis is another possibility. As always, etiology such as ischemic heart disease and primary pulmonary issues should be ruled out.


History and physical

The history should focus on symptoms such as angina, syncope or congestive heart failure (CHF). Clarify the febrile illness. One should keep in mind any co-morbid conditions that may affect how treatment proceeds. The physical will emphasize vitals, neuro exam, edema, vascular exam, heart and lungs.

Tests

  • EKG:  Get a baseline EKG and consider prolonged EKG monitoring in patients who complain of palpitations or if there is a concern for paroxysmal atrial fibrillation. The presence of paroxysmal atrial fibrillation might indicate the need of ablation (pulmonary vein isolation or complete Cox-Maze).
  • Echo. This is the most important piece of the puzzle in this scenario. The echocardiogram needs to be of high quality so that all valvular function can be adequately assessed. (Refer to technical note from chapter on Aortic Stenosis.) If there is any doubt of the findings or quality of the echo, then have it repeated by a cardiologist you trust or perform TEE. Other things to gain from the echo include the presence/absence of septal hypertrophy and annular sizes.
  • Cardiac catheterization: rule out any concomitant coronary artery disease (CAD). Also, right heart catheterization will give insight into resultant pulmonary hypertension from MR/MS.
  • CXR +/- CT scan: make sure there is no concomitant lung pathology. If there is evidence of calcified aorta, bicuspid aortic valve, or high-risk factors for atherosclerotic disease then get a CT.

Index scenario (additional information)

“It turns out that the patient had rheumatic fever as a teenager. He is otherwise healthy. His ejection fraction is 50%. He has what appears to be calcific aortic stenosis and rheumatic mitral stenosis by echo. A valve area of 0.7 cm2 and a mean gradient of 45 mmHg were noted for the aortic valve, while a valve area of 1.5 cm2 with thickened relatively immobile leaflets and moderate MR were noted for the mitral. TEE confirms these findings and shows a mean mitral gradient of 8 mmHg. Estimated PA systolic pressure was in the 40s. Right heart catheterization shows a PAP of 55 mmHg at rest. What are his options and what, if any, operation would you offer him?”


Treatment/management

This patient has severe aortic stenosis and moderate mitral stenosis. He is symptomatic with NYHA Class III. Operative choices include AVR with mitral valve repair or replacement versus AVR alone. The aortic stenosis meets indications for replacement (severe stenosis, symptomatic) and arguably the moderate mitral stenosis also meets indication for surgery (NYHA III, pulmonary hypertension). This presentation is typical of rheumatic heart disease and both valves can be affected with obstruction of flow. The procedure of choice for the mitral valve is replacement. Thus, a double valve replacement will provide the best results for this patient. The question of valve choice is also present. Given the patients age (75) he will be well-served by bioprosthetic valves in both positions. His freedom from structural valve deterioration (SVD) will be on the order of 85-90% at 10-15 years. Additionally, there are minimal thromboembolic and bleeding risks. If the patient were younger (< 60), then a mechanical valve would provide a lower rate of re-intervention (20-year freedom from re-intervention rate of 90%). Note if the patient had severe mitral stenosis and moderate AS then an AVR would still be advised. The reverse is not necessarily true. If moderate MS did not appear to be contributing to the patient’s clinical presentation (normal PAP, minimal dyspnea, 2+ stenosis) then you might consider aborting the mitral procedure especially if the patient was high risk.


Operative steps

Combined aortic/mitral valve replacement

Goals – relieve obstruction/eliminate regurgitation, replace the valves, myocardial protection, prevent embolization.

  • Large-bore IV access, arterial line, general endotracheal anesthesia (GETA), pulmonary artery catheter, foley.
  • Intraoperative TEE to recheck valvular pathology and rule out any other unexpected pathology.
  • Median sternotomy, elevate the right side of the pericardium, palpate the aorta for calcification. If there is any question of safety of cannulation site, then use the epiaortic ultrasound.
  • Heparinize (400 mg/kg), central aortic cannulation, bi-caval cannulation, retrograde cardioplegia cannula. At ACT of 480 CPB can be initiated.
  • Dissect Sondergard’s groove.
  • Insert antegrade cardioplegia catheter. Cross-clamp aorta and run antegrade cardioplegia for induction followed by retrograde. Intermittent doses of retrograde should be given throughout the operation. Delivery of cardioplegia into the coronary ostia with a handheld device should be considered if return of blood is poor during retrograde cardioplegia. If there is no return flow from the left ostia, then the retrograde catheter is likely not in place. An alternative at this point would be direct retrograde especially if if the approach to the mitral valve was trans-septal.
  • Aortotomy: make sure that you know where the RCA is. Make aortotomy ~1 cm above the RCA and extend the incision a short distance toward the left and then extend the incision to the right, obliquely towards the middle of the noncoronary sinus.
  • Inspect the aortic valve. Resect the leaflets along the annulus. Debride the calcium at this point (once the mitral valve has been replaced you run the risk of debriding your mitral annular sutures).The conduction system is particularly at risk with a double valve procedure.
  • An option that allows you to pressurize the left ventricle for testing the mitral valve after repair/replacement would be to do a simple running closure of the aortotomy at this point. Alternatively, a foley balloon catheter can be inflated in the LVOT to allow the LV to be pressurized during mitral valve testing.
  • The most common approaches to the mitral valve are the left atrial approach and the trans-septal approach.
  • For the left atrial approach: Make the left atriotomy in Sondergard’s groove. Insert self-retaining mitral retractor (i.e., Cosgrove retractor). Inspect the mitral valve. In this instance, both the leaflets and subvalvular apparatus appear thickened.
  • For the trans-septal approach: Make a right atriotomy and then incise the interatrial septum in the most posterior aspect towards the right. Anterior retraction of the left atrial septum results in excellent visualization of the mitral valve. The trans-septal incision is closer to the mitral valve than the left atriotomy incision. This procedure enables the assistant to see the mitral procedure and provide retraction. The trans-septal approach also provides a better visualization when there is fixation of the SVC and IVC.
  • Simultaneous sizing of the mitral and aortic valves is possible. This helps to demonstrate the impact of the mitral prosthesis on aortic valve sizing.
  • Perform a cord-sparing mitral valve replacement. Whether to excise any of the anterior or posterior leaflet is a personal/situational choice – you should do what you know and are comfortable doing. Keep in mind that it is hard to preserve thick cords and dividing the anterior leaflet is usually necessary in the setting of rheumatic disease. Take care near the posteromedial commissure. The conduction system is particularly at risk with a double valve procedure. Undersizing can result in patient-prosthetic mismatch, while oversizing can cause in failure to adequately seat the prosthetic valve and associated paravalvular leak.
  • Place horizontal mattress sutures of 2-0 braided polyester with pledgets along annulus (inverting/everting is your choice but if the annulus is calcified, ventricular to atrial sutures are best).
  • Pass the sutures through the valve ring. Seat the valve. Check the pledgets and then tie down the valve (beginning at the valve struts). Once the valve is tied down, remove the valve obturator. Remove your self-retaining retractor.
  • Check for paravalvular leak by pressurizing the left ventricle with saline. If happy with results, then decompress the left ventricle and close the left atriotomy.
  • If the initial aortotomy was closed, then reopen the aortotomy. Size your aortic valve.
  • Place stay sutures at the commissures – this will help orient the valve. Place horizontal mattress sutures of braided 2-0 polyester with pledgets along the annulus.
  • Pass the sutures through the valve ring and seat the valve.
  • Check the pledgets, and both coronary ostia. Tie the valve in place. Irrigate and recheck the ostia. Close the aortotomy with a running non-absorbable monofilament suture.
  • Transient complete heart block is common. Epicardial atrial and ventricular wires should be placed.
  • Deair, and wean from CPB.
  • Once off CPB, assess the valves with TEE.


Potential questions/alternative scenarios

“After separating from cardiopulmonary bypass, you note that the patient has a junctional bradycardia (ventricular escape in the 30’s). What is a possible cause and how could you have potentially prevented this?”

As in operations for isolated mitral or aortic valve disease, the location of the conduction system needs to be kept in mind. For the mitral portion of the procedure, care should be taken when placing annular sutures around the lateral aspect of A3. When replacing the aortic valve, care needs to be taken with annular sutures around the membranous septum (at the commissure of the right and non-coronary cusps). Furthermore, when replacing both valves, over sizing the valve could potentially cause compression of the conduction system between the new valves.

In this scenario, assuming the valves were not oversized, the etiology of the conduction abnormality likely had to do with overly aggressive placement of annular sutures in aforementioned areas. Epicardial atrial and ventricular wires should be placed in all patients who undergo double valve replacement. Most patients will recover an intrinsic rhythm. The need for permanent pacemaker placement is ~5% for isolated valve surgery (with the risk being 3-fold higher for multiple valve surgery).

“You have trouble defibrillating coming off bypass and the post-bypass TEE shows lateral wall motion abnormality.”

The important thing to remember in this situation is the intimate association of the circumflex with the mitral annulus. You have either distorted or injured the circumflex artery. In this scenario, you should re-heparinize immediately and go back on bypass. You will need your PA to get a length of vein adequate to bypass the circumflex. Take care when exposing the lateral wall as you now have a replaced mitral valve, and if you did any annular debridement, then you could potentially disrupt the AV groove. This scenario should be kept in mind for any mitral valve repair/replacement (refer to Mitral Valve Stenosis chapter for AV disruption).

“A 45-year-old otherwise healthy M (height: 5’10; Weight: 60 Kg) with a history of rheumatic fever presents with severe MS and severe AI. You perform a double valve replacement with mechanical prosthetics (AV size: 19 mm; MV size 33 mm). After coming of CPB, you notice blood pooling behind the heart. What happened?”

Keep in mind that when the heart is arrested, the mitral annulus can accommodate a larger prosthetic. Oversized mitral prosthetics can cause a LV rupture once the heart is contracting again after weaning CPB.

“A 19-year-old F presents with severe rheumatic MR and severe AS. The patient wishes to have children and therefore bioprosthetics are used. After replacing both valves and coming of CPB, anesthesia reports increased gradients across the LVOT. A strut of the mitral valve is noted to be protruding into the LVOT. What happened?”

It is imperative to verify that the struts of the mitral bioprosthetic are not encroached into the LVOT. Many prosthetic valves have markings that help avoid having struts directed into the LVOT. It’s something to keep in mind when a de novo increased gradient at the LVOT is noted while using mitral a bioprosthetic. In this instance, re-replacement of the mitral valve may be required. Modifying the orientation of the bioprosthetic may avoid the LVOT obstruction. However, mitral replacement with a mechanical valve will eliminate LVOT obstruction.


“Your patient has severe aortic stenosis and severe mitral regurgitation. On induction, the patient arrests. Why did this happen and what are you going to do?”

On induction the SVR drops. Venous return decreases. This leads to decreased coronary flow and ventricular failure. The incidence of arrest on induction with these combined lesions is higher than that for isolated severe AS.

In treating this patient, the first step is to secure the airway. Ventilate the patient. CPR should be going on. Heparinize and have the patient prepped/draped while you are scrubbing. Perform emergent sternotomy. Perform aortic and venous cannulation. Initiate cardiopulmonary bypass. Proceed with AVR/MVR as above.


“On preoperative workup, the symptomatic patient has severe mitral regurgitation and an AVA of ~0.9 cm2, but the gradient across the aortic valve is only 28 mmHg. How would you proceed?”
It is likely that there is low-gradient aortic stenosis in this situation. The calculation of AVA is dependent upon measurements of the LVOT (which can be operator-dependent by echo). As such, if you do not trust the study then repeat it with a cardiologist whom you are confident. The patient may need a TEE to better define calcification of the valve or the measurements of the LVOT (which directly affect the measurement of the AVA). If after these repeat tests there is still discrepancy, then the patient can get stress testing (treadmill or dobutamine). This should confirm severe AS (keep in mind that patients with contractile reserve benefit more from AVR). Proceed with the operation as indicated from that point forward. Also note that even if the patient has moderate AS and meets an indication for mitral repair due to severe regurgitation then the aortic valve should be replaced.

 
“You have an 85-year-old otherwise healthy patient who has severe calcific aortic stenosis and 2+ mitral regurgitation. There are no mitral leaflet abnormalities noted. How would you proceed?”  
This patient likely has functional mitral regurgitation that is accentuated by his/her severe aortic stenosis. The safest thing to do in this situation is the most expeditious operation possible. It is very likely that once the stenotic aortic valve has been replaced, then the mitral regurgitation will decrease to trace or mild– which in an 85-year-old patient can be medically managed without great fear of long-term complications. In other patients use the TEE to carefully delineate the mitral valve morphology and it may be worthwhile to “explore the valve” without necessarily committing to repair or replacement. If a definite structural abnormality is noted, then it may be repaired.


“A 65-year-old female presents with combined aortic insufficiency and mitral regurgitation. The AI is 3+ (moderately severe). She is short of breath with minimal exertion. Her EF is 45% and end diastolic volume is 7 cm2. TEE confirms that the MR is severe.”

For regurgitation, treat according to the dominant lesion and treat both if both are clearly contributing. In this case either the mitral or aortic could be contributing so both should be addressed by repair/replacement as deemed appropriate. If the MR were moderate (2+) then it is not indicated to repair/replace the valve. However, check the TEE and directly explore the valve if needed to rule out a structural lesion that is contributing to the regurgitation. If flail, chord rupture, or prolapse were noted you may be justified in repairing the valve if feasible, but rarely should you replace for moderate MR at the time of AVR. Conversely, if the aortic valve regurgitation were moderate and the mitral severe then treat the mitral valve and leave the aortic valve alone. Very rarely will moderate AI or moderate MR be the dominant lesion. Again, be sure to check the intraoperative TEE carefully to confirm that the lesions are indeed moderate and consider direct visual inspection if warranted.


Pearls/pitfalls

  • When faced with combined valvular disease use TEE to confirm the degree of regurgitation or stenosis.
  • Treat according to the dominant lesion.
  • Once you are in the OR for at least one valve that meets surgical indication then replace all severely stenotic valves. In this setting, repair/replace all severe or moderately severe regurgitant valves (3-4+).
  • The threshold for intervening on moderate aortic valve stenosis may be lowered in the setting of an MVR.
  • Moderate aortic regurgitation (2+) does not necessarily require repair in the setting of an MVR but requires evaluation by intraoperative TEE and possibly direct inspection.
  • Moderate mitral regurgitation (2+) does not necessarily require repair but requires evaluation by intraoperative TEE and possibly direct inspection depending on the TEE.
  • Moderate mitral stenosis should be carefully evaluated with right heart catheterization and TEE. Replace the mitral in the setting of an AVR if there is evidence that it is contributing to the clinical picture (elevated PAP, NYHA III-IV, atrial fibrillation).
  • Bioprosthetic valves are generally acceptable if patient > 60 years old.
  • Remember that the order of replacement/repair is imperative: open aorta, excise leaflets, and debride annulus prior to performing mitral replacement/repair.
  • Consider simultaneous sizing of aortic and mitral valves.
  • Size the aortic valve after replacing the mitral valve.
  • Take care not to oversize the mitral valve. This can lead to effective downsizing of the aortic valve and the possibility of having to use too small of an aortic valve (patient prosthesis mismatch).
  • As in any mitral repair or replacement, take care when placing sutures in the mitral annulus around P2 or P3.—do not want to compromise the circumflex artery.
  • After performing mitral valve replacement, avoid lifting the heart (see below).
  • Bright red blood coming from behind the heart after coming off bypass—think AV dissociation. Do not lift the heart to examine. Go back on bypass, then determine where blood is coming from and repair as appropriate.
  • Minimally invasive approaches for concomitant aortic and mitral valve surgery via right-sided mini thoracotomy are feasible with acceptable outcomes in centers with known experience in this area.
  • See pearls/pitfalls in the chapters on aortic stenosis, mitral stenosis, mitral regurgitation


Suggested readings

  • Bonow B. Tricuspid, Pulmonic and Multivalvular Disease. Braunwald’s Heart Disease—A textbook of Cardiovascular Medicine, 9th ed. 2011.
  • Gillinov AM, Blackstone EH, Cosgrove DM, et al. Mitral valve repair with aortic valve replacement is superior to double valve replacement. J Thorac Cardiovasc Surg 2003;125:1372-87.
  • Carpentier A, Adams D, Filsoufi F. Carpentier’s Reconstructive Valve Surgery. Section II, IV, V. 2010.
  • Nishimura R, Grantham JA, Connolly HM, et al. Low-Output, Low-Gradient Aortic Stenosis in Patients With Depressed Left Ventricular Systolic Function: The Clinical Utility of the Dobutamine Challenge in the Catheterization Laboratory. Circulation. 2002;106:809-813.
  • Gillinov AM, Gelijns AC, Parides MK, et al. Surgical ablation of atrial fibrillation during mitral-valve surgery. N Engl J Med. 2015;372(15):1399-409.
  • Frank S, Pedro DN, Scott S. Sabiston and Spencer Surgery of the Chest, 9th ed. 2015
  • Kirklin, Barratt-Boyes Cardiac Surgery, 4th ed. 2013
  • Falk V, Baumgartner H, Bax JJ, et al. 2017 ESC/EACTS Guidelines for the management of valvular heart disease. Eur J Cardiothorac Surg. 2017;52(4):616-664.
  • Nishimura RA, Otto CM, Bonow RO, et al. 2017 AHA/ACC Focused Update of the 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2017;135(25):e1159-e1195.
  • Lamelas J. Minimally invasive concomitant aortic and mitral valve surgery: the “Miami Method”. Ann Cardiothorac Surg. 2015;4(1):33-7.
  • Ando T, Takagi H, Briasoulis A, et al. A systematic review of reported cases of combined transcatheter aortic and mitral valve interventions. Catheter Cardiovasc Interv. 2018;91(1):124-134.
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