Transcatheter mitral valve repair (TMVR) is indicated in some patients with severe mitral regurgitation (MR). This procedure is an option for patients when surgical intervention is not considered appropriate. This article explores indications for TMVR and risks associated with the procedure. Diagnostic testing, post-procedural management, and critical care nursing considerations are also outlined.
Etiology. MR, also known as mitral insufficiency, is the most prevalent form of valvular heart disease in the US.1 Approximately 1 in 10 people age 75 and older have moderate-to-severe or severe MR.2 There are two primary causes of MR, known as degenerative and functional MR. Degenerative MR, also known as primary or organic MR, is caused by an anatomical abnormality of the mitral valve. This includes abnormalities of the valve leaflets and the subvalvular apparatus, including the papillary muscles and chordae tendineae. The most common cause of degenerative MR is mitral valve prolapse. Other causes of degenerative MR include infective endocarditis, connective tissue disorders, radiation heart disease, trauma leading to flail mitral leaflet, and rheumatic heart disease.3
Functional MR, alternatively known as secondary MR, is caused by primary left ventricular dysfunction. Left ventricular dysfunction causes include coronary heart disease or nonischemic cardiomyopathy.3 This leads to left ventricular dilation, causing a displacement of the papillary muscles allowing for incomplete closure of the mitral valve causing regurgitation.
Pathophysiology. The mitral valve is a complex structure located between the left atrium and left ventricle. (See Mitral regurgitation.) The mitral valve is composed of the annulus, anterior and posterior leaflets, papillary muscles, and chords.4 (See Mitral valve anatomy.) In a properly functioning heart, the mitral valve allows blood to flow in one direction from the left atrium to the left ventricle. When MR is present, there is retrograde flow from the left ventricle to the left atrium during ventricular systole because of mitral valve dysfunction. This leads to decreased cardiac output. If MR progresses to a moderate-to-severe form, the left ventricle sustains an increased demand to meet the body's oxygenated blood requirement. MR is a progressive disease, and over time, if left untreated, may lead to heart failure and death.
The first phase of MR progression is known as the compensated phase. During this phase, the left ventricle begins to enlarge and the patient typically remains asymptomatic. The second phase is known as the transitional phase. This phase is characterized by a weakened myocardium, in which the ventricle is no longer able to compensate for the MR. During this phase, patients may or may not demonstrate signs and symptoms, including shortness of breath, decreased endurance, and increased fatigue. The third stage is known as the decompensated phase. During this phase, patients may experience cardiac dysrhythmias, pulmonary hypertension, and heart failure.5
Clinical manifestations. Many patients with severe MR are initially asymptomatic. When symptoms develop, they include exertional dyspnea and fatigue. Another common clinical presentation is paroxysmal or persistent atrial fibrillation.5
The quality, duration, timing, intensity, and radiation of the murmur are dependent on the cause of the murmur.6 The murmur of MR is best heard at the apex, or fifth intercostal space in the left midclavicular line during systole and is described as blowing and high-pitched. It can radiate to the left sternal edge and the axilla, depending on jet positioning and intensity.7 (See Grading heart murmur intensity.)
Diagnosis. When diagnosing MR, a transthoracic echocardiogram (TTE) is recommended to assess pulmonary artery pressures, and the size and function of the cardiac chambers.6 TTE will determine the etiology and severity of the MR. In patients with early MR, TTE typically shows an increased left atrial size with normal left ventricular size and systolic function. As the disease progresses to chronic MR, the TTE will demonstrate a dilated left ventricle and decreased ejection fraction.6 When determining the severity of MR, clinicians should evaluate the following measurements: regurgitant volume, effective orifice area, and regurgitant fraction using proximal isovelocity surface area or quantitative Doppler flow.8,9 Proximal isovelocity surface area, also known as flow convergence method, is a measurement that aides clinicians in determining the severity of MR. With increased flow proximal to a circular orifice, a hemisphere is created with multiple layers. The radius of the hemisphere is used to calculate the orifice diameter or quantitative Doppler flow.8 Severe MR valve is identified by the presence of some of the following criteria:
- a central jet of MR >40% of the left atrium or holosystolic eccentric MR
- vena contracta (the narrowest central flow region of a jet occurring at or downstream of the orifice of a regurgitant valve) ≥ 0.7 cm (mild <0.3 cm, moderate 0.3 to 0.69 cm, severe ≥ 0.7 cm)9,10
- regurgitant volume ≥ 60 mL
- regurgitant fraction ≥ 50%
- effective regurgitant orifice area ≥ 0.40 cm2
- angiographic grade 3-4+.8
In the case of a suboptimal TTE, a transesophageal echocardiogram (TEE) with real-time three-dimensional imaging is warranted.11 If the results of the TEE are inconclusive, a cardiovascular MRI can be used to evaluate the severity of MR. If the previously mentioned studies are inadequate or conflicting, a stress test or cardiac catheterization is indicated.6
Management. Individuals with mild or moderate MR often do not require intervention but need continued monitoring over time. There are several treatment options for individuals in whom intervention is warranted. These options include the gold standard, which is surgical intervention via open-heart surgery, but also transcatheter repair or replacement of the mitral valve, medications to suppress cardiac dysrhythmias caused by mitral valve disease, and medications to decrease the heart's workload.3
A multidisciplinary heart team consisting of cardiac surgeons, interventional cardiologists, heart failure and valve specialists, imaging specialists, and cardiac anesthesiologists will work collaboratively to determine surgical risk and best treatment options.
Indications. Patients demonstrating severe heart failure symptoms (New York Heart Association Class III to IV) with chronic primary (degenerative) moderate-to-severe or severe (3+ or 4+) MR are potential candidates for TMVR. Patients whose anatomy favors the procedure, who have fair life expectancy (greater than or equal to 2 years) and comorbidities that prohibit surgery due to high risk, and are on optimal guideline-directed medications for heart failure may be considered TMVR candidates.12
Patients are considered at prohibitive risk for surgical intervention by the heart team if they have a Society of Thoracic Surgeons Predicted Risk of Mortality (PROM) score (a well-validated predictor of 30-day mortality after cardiac procedures) of greater than or equal to 8% after mitral valve replacement or greater than or equal to 6% after mitral valve repair.13 Additionally, patients with a porcelain aorta (heavy circumferential calcification or severe atheromatous plaques of the entire ascending aorta extending to the arch), severe liver disease, pulmonary hypertension, hostile chest (a condition making sternotomy or right anterior thoracotomy prohibitively hazardous due to abnormal chest wall anatomy, complications from prior surgery, severe radiation damage, multiple recurrent pleural effusions, and other reasons), frailty, or unusual extenuating circumstances are considered at prohibitive risk for surgical intervention.2,14
Select patients with chronic secondary MR who continue to be symptomatic, displaying MR grade 3+ or 4+ despite taking optimal guideline-directed medications for heart failure, are now considered candidates for TMVR according to the FDA. These patients will demonstrate a left ventricular ejection fraction of 20% to 50% and have a left ventricular end-systolic dimension of 70 mm or less. This recent update was released in March 2019, based on data collected during the Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation (COAPT) trial.15 The COAPT trial found that patients with moderate-to-severe or severe secondary MR who underwent TMVR had a decreased rate of hospitalization for heart failure and a lower all-cause mortality within 24 months of follow-up when compared with medical therapy alone.16
Contraindications. Contraindications to TMVR for patients with degenerative MR include rheumatic mitral valve disease, intolerance of procedural anticoagulation or post-procedural antiplatelet agents, active endocarditis of the MV, and thrombus of femoral vein, inferior vena cava, or intracardiac thrombus.11
If TMVR is the chosen intervention, the patient will undergo a series of tests prior to the procedure. As previously mentioned, a baseline TTE is essential to evaluate mitral valve morphology and etiology of regurgitation. Ultimately a TEE is needed to confirm findings. The TEE will provide measurements regarding the coaptation point of the valve leaflets to ensure proper clip positioning, and also help determine the best location for the transseptal puncture. A coaptation length greater than 2 mm and a coaptation depth less than 11 mm are favorable for safe positioning of the clip.17 The patient will need to meet with the cardiac surgeon, interventional cardiologist, heart and valve specialists, and other members of the heart team for further evaluation and workup. The valve clinic coordinator will also be available to provide further education. Other evaluations include pulmonary function testing, Kansas City Cardiomyopathy Questionnaire (a 23-item self-administered questionnaire that measures a patient's perceived health status, including heart failure symptoms and their heart failure's impact on physical and social function and their quality of life), blood work, right- and left-heart catheterization, and a 6-minute walk test to determine exercise ability.18,19
The MitraClip technology is based on the surgical technique known as the Alfieri stitch, or edge-to-edge repair, in which a double orifice of the mitral valve is created with a clip.20 This technique is used to decrease the size of the orifice to reduce the severity of MR. The MitraClip device is constructed out of cobalt chromium and has a polyester cover, which supports tissue growth. The clip is properly positioned via the steerable guide catheter and the clip delivery system.
During this minimally invasive transcatheter procedure, a catheter is inserted through the femoral vein and guided to the right atrium. A transseptal puncture is performed in order to gain access to the left atrium where the MitraClip catheter is then advanced. With the assistance of fluoroscopy and TEE, the MitraClip device can align with the regurgitant valve leaflets and advance into the left ventricle. The MitraClip system is slowly retracted from the left ventricle with the clip arms open in order to grasp the leaflets at the site of regurgitation. The clip arms are closed, and via Doppler echocardiography the clinician can visualize the degree of MR and positioning of the clip. If the clip positioning is not optimal, the arms can be reopened and the placement of the clip can be adjusted prior to final deployment. An additional clip may be warranted in certain circumstances in order to further reduce MR, which occurs in approximately 40% of patients.11 Once the delivery system is removed, hemostasis of access site is achieved, generally with a figure-of-eight suture. During the procedure, the patient is endotracheally intubated under general anesthesia, requires venous access and arterial line placement for invasive hemodynamic monitoring, and has a urinary catheter inserted and a TEE probe in place.2 Patients will require a heparin infusion during the procedure to achieve an activated clotting time of greater than 250 seconds, which is essential after transseptal puncture, to prevent potential embolic events as there is increased risk of thrombus formation on devices used during the procedure.11,21
Immediately after the procedure, the patient is transferred to the ICU to monitor for complications and to complete a prophylactic antibiotic regimen. To ensure smooth transition from the OR to the ICU, communication among the physicians, anesthesiologists, NPs, PAs, and nurses is critical. Patients remain on strict bed rest for 6 hours (follow hospital protocol) with a goal of early ambulation. The critical care nurse will conduct frequent neurovascular assessments, assessing lower extremity pulses and monitoring groin access sites. If at 6 hours the patient is free of bleeding and other complications, the critical care nurse will remove the urinary catheter and discontinue the arterial line. The day after the procedure, an ECG, blood work, chest X-ray, and a 2-D TTE are completed. The critical care nurse will also discontinue the figure-of-eight suture from the access site the morning following the procedure. Patients can be discharged the day following the procedure if no complications arise. Prior to discharge, patients will start dual antiplatelet therapy consisting of lifelong daily aspirin, and clopidogrel for 6 months.
Complications associated with TMVR include bleeding at the access site due to the large sheath size (24 French) required for the procedure. The rate of bleeding has been reported to be lower in the TMVR group when compared with those who underwent surgical intervention. The Endovascular Valve Edge-to-Edge Repair Study II – (EVEREST II) trial demonstrated that 13% of patients in the TMVR group compared with 45% of patients in the surgical group required two or more units of blood.11 The TMVR registry reports 0.9% to 3.9% of patients requiring 2 or more units of blood due to bleeding. Another potential complication is device embolization or clip detachment. In the EVEREST II study, a total of nine patients were found to have a partial clip detachment within the first 12 months.11 If the clip were to partially detach, the treatment would require surgical intervention.
The development of mitral stenosis post-TMVR is a rare but potential complication. This can occur due to the development of an increased diastolic pressure gradient across the mitral valve.11 Infective endocarditis is a potential complication, but due to limited data there has not been an established plan for antibiotic prophylaxis. Other potential complications include: allergic reaction, dysrhythmias, cardiac arrest, cardiac tamponade or pericardial effusion, chordal rupture or entanglement, emboli, stroke, or transient ischemic attack.2
According to the Transcatheter Mitral Valve Interventions (TRAMI) registry, the rate of in-hospital major adverse cardiac and cerebrovascular events was 2.7% for death, stroke, and myocardial infarction.22 The 5-year results of EVEREST II demonstrated that patients who underwent TMVR required surgical intervention for residual MR during the first year after the procedure when compared with patients who underwent surgery for MR. The period of follow-up from year 1 to year 5 revealed low rates of surgery for mitral valve dysfunction in both percutaneous and surgical therapy groups, demonstrating the durability of MR reduction for both approaches.23
Critical care nursing considerations
Preprocedure critical care nursing considerations include performing baseline neurologic, cardiovascular, and neurovascular assessments to aid in the identification of postprocedural complications. Nurses should also review lab work results, ensure anticoagulant agents were held for 3 days prior to procedure (if patient was taking medications at home), review allergies, and perform medication reconciliation.11
Postprocedure critical care nursing considerations include monitoring for neurovascular changes, neurologic deficits, cardiovascular changes, bleeding, and dysrhythmias. Critical care nurses should monitor vital signs, access sites, and lower extremity pulses frequently (follow hospital protocol). Patients and their family members should be educated on the importance of following bedrest instructions. When bedrest per hospital protocol has been completed, critical care nurses may begin to advance activity with the goal of early ambulation and establish daily walking schedules. Critical care nurses are responsible for maintaining accurate fluid intake and output records, collecting lab specimens, and reporting any abnormal lab values.
When discharged, patients may slowly regain their activities of daily living. Patients should be instructed not to lift, pull, or push anything heavier than 10 lb (4.5 kg) for the first week after discharge. Patients should be instructed on incision care, signs of infection/bleeding, chest pain, shortness of breath, and when to call the physician. For the first 4 weeks, patients should not submerge their incision in water, such as in a tub or pool, until the incision has completely healed. Patients can shower the day of discharge using a mild, unscented soap and gentle bathing motions taking care not to rub incisions. Encourage the patient to continue their daily walking program to reach a goal of walking 20 to 30 minutes every day, ensuring they recognize the signs of progressive activity intolerance and when to call the physician. Additionally, instruct patients to monitor their BP and heart rate at home and take medications as prescribed. Ensure the patient was provided his or her implant card and educate them on the importance of carrying this card at all times.
The patient should follow up with the structural heart team 30 days after the procedure. At this appointment, the patient will complete a 12-lead ECG, the Kansas City Cardiomyopathy Questionnaire, a transthoracic echocardiograph to assess the positioning and function of the MitraClip, and blood work to monitor kidney function and for signs of anemia. Additionally, the provider will assess the New York Heart Association classification at the follow-up appointment and evaluate the access site for signs of infection or bleeding. Patients will be transitioned back to their primary care provider and primary cardiologist and follow up with the structural heart team in 1 year where they will complete the above-mentioned diagnostic testing in addition to a 6-minute walk test.
When surgical and medical interventions are contraindicated for patients with severe MR, TMVR is a potential alternative treatment. Critical care nurses should be familiar with preprocedure patient instructions, the TMVR procedure, and postprocedure nursing considerations. Patient and family education is key to ensuring optimal patient outcomes.
1. Moore M, Chen J, Mallow PJ, Rizzo JA. The direct health-care burden of valvular heart disease: evidence from US national survey data. Clinicoecon Outcomes Res
3. Gaasch WH. Patient education: mitral regurgitation (beyond the basics). UpToDate. 2020. www.uptodate.com
4. Antoine C, Mantovani F, Benfari G, et al. Pathophysiology of degenerative mitral regurgitation: new 3-dimensional imaging insights. Circ Cardiovasc Imaging
5. Gaasch WH. Natural history of chronic mitral regurgitation caused by mitral valve prolapse and flail mitral leaflet. UpToDate. 2019. www.uptodate.com
6. Otto CM. Clinical manifestations and diagnosis of chronic mitral regurgitation. UpToDate. 2019. www.uptodate.com
7. Meyer TE. Auscultation of cardiac murmurs in adults. UpToDate. 2019. www.uptodate.com
8. Nishimura RA, Otto CM, Bonow RO, et al. 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
9. Lambert AS. Proximal isovelocity surface area should be routinely measured in evaluating mitral regurgitation: a core review. Anesth Analg
10. Zeng X, Levine RA, Hua L, et al. Diagnostic value of vena contracta area in the quantification of mitral regurgitation severity by color Doppler 3D echocardiography. Circ Cardiovasc Imaging
11. Armstrong EJ, Foster E. Transcatheter mitral valve repair. UpToDate. 2019. www.uptodate.com
12. 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
13. Puskas JD, Kilgo PD, Thourani VH, et al. The society of thoracic surgeons 30-day predicted risk of mortality score also predicts long-term survival. Ann Thorac Surg
14. Kappetein AP, Head SJ, Genereux P, et al. Updated standardized endpoint definitions for transcatheter aortic valve implantation: the Valve Academic Research Consortium-2 Consensus Document. J Am Coll Cardiol
15. Goel K. Secondary MR: how has the COAPT trial changed our approach? 2019. www.acc.org/latest-in-cardiology/articles/2019/05/10/14/40/secondary-mr
16. Stone GW, Lindenfeld J, Abraham WT, et al. Transcatheter mitral-valve repair in patients with heart failure. N Engl J Med
17. Sherif MA, Paranskaya L, Yuecel S, et al. MitraClip step by step: how to simplify the procedure. Neth Heart J
19. Spertus J. Medical Device Development Tool (MDDT) Qualification Decision Summary for Kansas City Cardiomyopathy Questionnaire (KCCQ). 2016. www.fda.gov/media/108301/download
20. Rassaf T. The cardiologist's way to do the Alfieri stitch: transcatheter mitral valve edge-to-edge repair revisited. J Thorac Dis
21. Saia F, Biagini E, Berardini A, et al. Antithrombotic management during percutaneous mitral valve repair with the Mitraclip system in a patient with heparin-induced thrombocytopenia. TH Open
22. Eggebrecht H, Schelle S, Puls M, et al. Risk and outcomes of complications during and after MitraClip implantation: experience in 828 patients from the German TRAnscatheter Mitral Valve Interventions (TRAMI) registry. Catheter Cardiovasc Interv
23. Feldman T, Kar S, Elmariah S, et al. Randomized comparison of percutaneous repair and surgery for mitral regurgitation: 5-year results of EVEREST II. J Am Coll Cardiol