Amir A. Sarkeshik and Victor Rodriguez
This chapter is a revision and update of that included in previous editions of the TSRA Review written by Lawrence E. Greiten (2nd edition) and Ahmet Kilic (1st edition).
Background
The interaction between ischemic and valvular heart disease is complex and can present as independent, inter-related or incidental during the work-up of either process. Both pathologies can affect ventricular morphology, physiology and function at various stages, and to different degrees. As such, the clinical impact of one on the other during surgical management is indisputable. Co-existing pathology make for longer, more complex operations — posing a higher risk for early and late mortality when compared to either procedure alone. Work-up needs to be sensible, comprehensive, and thorough. In patients undergoing coronary re-vascularization, an echocardiogram needs to be performed to assess the valves. In reverse, valve patients who are >40 years of age, post-menopausal, or considered moderate-to-high risk for CAD (based on established risk calculations) require diagnostic coronary catherization. The root cause of any notable myocardial dysfunction must be highlighted and delineated between the two pathologies for optimal management.
Current trends in concomitant surgery include
1. CABG + AVR
2. CABG + MVR/r
3. CABG + AVR + MVR
Aortic Valve + Coronary Artery Disease
Aortic Stenosis (AS) is a frequently encountered valvular pathology in the adult population— typically due to degenerative, calcific disease. AS increases the LV after-load, leading to progressive concentric ventricular hypertrophy and ultimately a drop in LV diastolic compliance. Coronary flow reserve (CFR) is subsequently decreased to keep up with the increased O2 demand of the hypertrophied LV. Given that AS is mostly seen in adults >60 years of age, it is not by surprise that concomitant coronary disease is frequently encountered — further undermining the CFR. Having said that, treatment of co-existing disease can be gratifying as the response to surgical relief is often immediate, dramatic, and durable.
Aortic Insufficiency (AI) is less commonly seen in those >60 years of age and as such not as frequently encountered in co-existence with CAD. Common causes include annuloaortic ectasia, rheumatic heart disease, congenital bicuspid valves, endocarditis, and connective tissue disorders. AI results in increased diastolic volume, ventricular dilatation, and wall stress. This leads to an increased O2 demand and reduced CFR. Concomitant CAD can lead to added LV dilation and myocardial dysfunction. Patients with co-existing disease states typically present in one of following ways (1) symptomatic CAD with an incidental AI found during work-up; (2) asymptomatic AI and CAD that were discovered due to a diastolic murmur on routine exam and (3) CHF due to LV overload from AI, ischemic myopathy from CAD or a combination of both.
Indications for concomitant AVR in patients undergoing CABG
Indication for concomitant CABG in patients undergoing AVR/r
Significant CAD
1. Lesions ≥70% reduction in luminal diameter in major coronaries
2. Can consider lesion ≥50% that have reasonable targets
Key operative steps: CABG + AVR
- TEE
- Cannulation for CPB
- Cross-clamp aorta and administer antegrade + retrograde cardioplegia
- LV Vent
- Distal venous graft anastomoses
- Aortotomy with standard oblique incision
- Resection of the aortic valve [do not replace at this stage]
- Left atriotomy following dissection into inter-atrial groove
- Perform any indicated atrial fibrillation procedure
- Mitral valve repair or replacement with prosthesis of choice
- Closure of left atriotomy
- Aortic valve replacement with prosthesis of choice
- Closure of aortotomy
- Perform distal mammary anastomosis
- Perform proximal graft anastomoses
NOTE: In patients with severe AS and a hypertrophied heart, it is important to keep the LV filled when weaning off CPB to prevent excessive LVOT obstruction during systole and provide an adequate preload.
Mitral Valve and Coronary Artery Disease
The mitral valve is intimately connected to the LV through its choral attachments. As expected, normal valve function ultimately depends on the health of the LV. Similarly, LV function is reliant on a competent mitral valve. It is this underlying, co-dependent relationship that accentuates the complex, inextricable association between coronary artery ischemia and mitral valve disease.
Mitral Valve Regurgitation (MR) from annular dilatation is caused by either ischemic or non-ischemic changes. Ischemic MR (IMR) can either be acute, from papillary muscle rupture or chronic — from progressive annular dilation, LV remodeling, or geometric distortions of the sub-valvular apparatus. Successful management has garnered the attention of much debate over the past decade and optimal therapy remains controversial. Non-ischemic (“organic”) causes of MR include myxomatous disease, rheumatic disease, trauma, iatrogenic injury, and infective endocarditis.
Mitral Valve Stenosis (MS) is most often caused by rheumatic disease and classified into mild, moderate, or severe based on valve area and associated gradient. Unlike ischemic MR, mitral stenosis and CAD do not have synergistic, interdependent pathologies — making their management more feasible. Presentation is typically secondary to a symptomatic MS with shortness of breath, fatigue, and orthopnea.
Indications for concomitant MVR/r and CABG
- Severe IMR not likely to resolve with coronary revascularization alone
- Moderate IMR not likely to resolve with coronary revascularization alone
- Mild MR with HF symptoms
- Moderate-to-severe MS
NOTE: When possible, MV should be repaired, with replacement being reserved for non-repairable valves or valves with severe organic dysfunction.
Indication for concomitant CABG in patients undergoing MVR/r
Significant CAD
1. Major coronary lesions with ≥70% reduction in luminal diameter
2. May consider lesion ≥50% that have reasonable targets / clinical benefit
Key Operative Steps: CABG + MVR/r
- TEE
- Cannulation for CPB
- Cross-clamp aorta and administer antegrade + retrograde cardioplegia
- LV Vent
- Distal venous graft anastomoses
- Left atriotomy following dissection into inter-atrial groove
- Ablation ± LA appendage ligation in case of concomitant atrial fibrillation
- Mitral valve repair or replacement with prosthesis of choice
- Closure of left atriotomy
- Perform distal mammary anastomosis
- Perform proximal graft anastomoses
Aortic Valve / Mitral Valve and Coronary Artery Disease
Combined aortic and mitral valve disease typically present is earlier than isolated valvular disease. In the setting of AS and CAD, MVR is indicated for moderate-to-severe insufficiency. Insufficiency of both valves is usually secondary to rheumatic heart disease. Presentation can be dominated by AI symptomatology — with the MR being secondary to the CAD or AI. Judicious work-up is thus required in these patients for appropriate surgical management. A thorough H&P needs to be performed with special attention on any heart failure symptoms. Further work-up should include an echocardiogram and coronary angiography to verify structural and physiologic deficits. Patients with irreversible, severe ventricular dysfunction may be at prohibitive risk for surgery as they would not tolerate procedure.
Key Operative Steps: CABG + AVR / MVR/r
- TEE
- Cannulation for CPB
- Cross-clamp aorta and administer antegrade + retrograde cardioplegia
- LV Vent
- Distal venous graft anastomoses
- Aortotomy with standard oblique incision
- Resection of the aortic valve [do not replace at this stage]
- Left atriotomy following dissection into inter-atrial groove
- Perform any indicated atrial fibrillation procedure
- Mitral valve repair or replacement with prosthesis of choice
- Closure of left atriotomy
- Aortic valve replacement with prosthesis of choice
- Closure of aortotomy
- Perform distal mammary anastomosis
- Perform proximal graft anastomoses
Other Considerations
The most important risk factors for 1-year mortality include advanced age, cardiogenic shock, and heart failure. The postoperative care of patients with concomitant disease is of utmost importance and can often be tenuous. Patients can often get sicker prior to improving. Correction of AR can lead to a reduced preload while repair of MR can cause an immediate rise in afterload. A dilated or ischemic ventricle may not have the reserve to maintain adequate forward flow and can further decompensate. Moreover, it may take time for coronary revascularization to recruit adequate hibernating myocardium for functional recovery. As such, there is no one way to manage these patients and optimal care depends on special attention to biventricular function, cardiopulmonary physiology, and systemic perfusion.
Suggested Readings
- Nishimura RA, Otto CM, Bonow RO, et al. 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 Practice Guidelines. Circulation 2014;129(23):e521–e643.
- Vahanian A, Baumgartner H, Bax J, et al. Task Force on the Management of Valvular Hearth Disease of the European Society of Cardiology, ESC Committee for Practice Guidelines. Guidelines on the management of valvular heart disease (version 2012): the Joint Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2012;33:2451–2496.
