MV replacement is indicated for:
A. A 65-year-old man with dyspnea, severe MR, and posterior on echocardiography
B. A 25-year-old man with recent intravenous drug abuse and mitral valvular endocarditis with an anterior leaflet vegetation greater than 1.5 cm in greatest dimension
C. A 55-year-old woman with dyspnea with minimal activity and moderate MS with thickening of the leaflets and severe fibrosis and shortening of the chordae that is not amenable to percutaneous mitral balloon valvuloplasty
D. A 70-year-old man with 3-vessel coronary artery disease, a non-ST-segment elevation myocardial infarction and ischemic mitral regurgitation
Answer: C. MV replacement is indicated for moderate MS with NYHA class III symptoms when percutaneous mitral balloon valvuloplasty is not an option. MR with posterior leaflet prolapse is often amenable to repair, as is mitral valvular endocarditis not responding to medical therapy. Ischemic mitral regurgitation often responds to MR and usually does not require MV replacement.
A bioprosthetic valve is preferable to a mechanical valve for MV replacement for:
A. A 45-year-old man with severe MR and mitral valvular endocarditis with a 9-mm vegetation on the anterior leaflet and peripheral emboli despite treatment with antibiotics
B. A 35-year-old woman with rheumatic heart disease and severe MS who wishes to conceive
C. A 60-year-old man with atrial fibrillation on warfarin anticoagulation and severe MS
D. A 55-year-old woman with severe MS
Answer: B. A bioprosthetic valve is appropriate in a woman of child-bearing age who wishes to conceive. After the woman is has completed child bearing, she can undergo reoperation for replacement with a mechanical valve with postoperative warfarin anticoagulation.
When performing combined aortic valve replacement (AVR), MV replacement and 2-vessel coronary artery bypass with the left internal mammary artery to the left anterior descending artery and a saphenous vein graft to the obtuse marginal branch of the left circumflex artery, the correct order of procedures is:
A. Excise aortic valve, MV replacement, aortic valve replacement, distal anastomoses, proximal anastomosis.
B. Distal anastomoses, excise aortic valve, aortic valve replacement, MV replacement, proximal anastomosis.
C. Distal anastomoses, MV replacement, excise aortic valve, aortic valve replacement, proximal anastomosis.
D. Distal anastomoses, excise aortic valve, MV replacement, aortic valve replacement, proximal anastomosis.
Answer: D. When performing combined AVR and MV replacement with coronary artery bypass, distal anastomoses should be performed first. Next the aortic valve should be excised, since this can disrupt the MV replacement if it was done before excision of the aortic valve. After replacing the MV, the heart should no longer be lifted to minimize the risk of posterior LV rupture. The aortic valve replacement is then performed and the proximal anastomosis is performed last after closure of the aortotomy.
The chordal sparing technique of MV replacement has:
A. Reduced the incidence of postoperative thromboembolic complications
B. Not improved survival after MV replacement
C. Been associated with increased risk of left ventricular rupture when the posterior leaflet is preserved
D. Been associated with improved left ventricular function compared to the nonchordal sparing technique.
Answer: D. The chordal sparing technique of MV replacement has no impact on the incidence of postoperative thromboembolic complications, but LV function and postoperative survival are both improved. The risk of LV rupture is less with preservation of the posterior leaflet and the chordal sparing technique.
The risk of thromboembolic complications after MV replacement is:
A. Higher in mechanical prosthesis with anticoagulation than with mechanical AVR with anticoagulation
B. Less with a mechanical valve with anticoagulation than with a bioprosthetic valve without anticoagulation
C. Not affected by poor ventricular function with a left ventricular ejection fraction less than 30 percent
D. Is negligible in a patient with a mechanical valve and warfarin anticoagulation
Answer: A. The risk of thromboembolic complications after mechanical MV replacement with anticoagulation is higher than with mechanical AVR with anticoagulation. Thromboembolic complications occur in 1 to 2 percent of patients after mechanical MV replacement despite anticoagulation with a goal INR of 2.5 to 3.5, compared to 0.7 percent of patients with a bioprosthetic MV replacement. Low LV ejection fraction (<30 percent), atrial fibrillation, previous thromboembolism, and a hypercoagulable state increase the risk of thromboembolic complications and are indications for the addition of aspirin to warfarin anticoagulation.