Show notes
CardioNerds (Amit Goyal and Daniel Ambinder) join Dr. Jaya Kanduri, Dr. Dan Lu, and Dr. Joe Wang from Weill Cornell Cardiology for Levain cookies in Central Park. The ECPR is provided by Dr. Harsimran Singh (Cardiology Program Director and Interventional Cardiologist with expertise in ACHD). Episode introduction by CardioNerds Clinical Trialist Dr. Jeremy Brooksbank.
We discuss a case of a 24-year-old female with a history of unicuspid aortic valve with associated aortopathy status post mechanical aortic valve replacement and Bentall procedure at age 16 presents with acute onset substernal chest pain and shortness of breath. She was found to have mechanical aortic valve obstruction and severe aortic regurgitation resulting in cardiogenic shock. Unfortunately, the shock quickly progressed to refractory cardiac arrest requiring mechanical support with VA-ECMO before valve debridement was performed in the operating room. The differential for mechanical prosthetic valve stenosis includes pannus, thrombus, or vegetation. She was eventually found to have thrombus obstructing the outflow tract and holding the mechanical leaflets open leading to torrential regurgitation. She underwent successful surgical debridement. We discuss unicuspid aortic valve and associated aortopathy, surgical considerations regarding AVR, diagnosis and management of prosthetic valve dysfunction, approach to cardiogenic shock and considerations around activating and managing VA-ECMO.
With this episode, the CardioNerds family warmly welcomes Weill Cornell Cardiology to the CardioNerds Healy Honor Roll. The CardioNerds Healy Honor Roll programs support and foster the the CardioNerds spirit and mission of democratizing cardiovascular education. Healy Honor Roll programs nominate fellows from their program who are highly motivated and are passionate about medical education. The Weill Cornell fellowship program director, Dr. Harsimran Singh has nominated Dr. Jaya Kanduri for this position.
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Disclosures: NoneJump to: Pearls - Notes - References
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Case Media
ECGCXREchoRHC
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Episode Teaching
Pearls - Mechanical Valve Thrombosis
(1) Unicuspid aortic valves present with aortic stenosis earlier in life. There can be concurrent aortic regurgitation and, like bicuspid aortic valves, unicuspids can be associated with aortopathy as well as other congenital anomalies.
(2) Prosthetic valve stenosis is assessed with different echocardiographic parameters than what we use for native valves. The differential for mechanical valve stenosis includes pannus, thrombus, or vegetation. Patient prosthesis mismatch may also lead to elevated gradients.
(3) VA-ECMO provides robust flow in the setting of cardiogenic shock as well as gas exchange. While this flow may improve end-organ perfusion, it also increases left ventricular afterload, thereby potentially worsening LV ischemia and impeding LV recovery. Elevated afterload may also decrease innate contractility and prevent aortic valve leaflets from opening. Therefore, if a patient with a mechanical valve is on VA-ECMO, ensuring valve opening to prevent valve (or ventricular) thrombosis is paramount.
(4) Venting is sometimes necessary to decrease the left ventricular end diastolic pressure from the high afterload imposed by VA-ECMO. A microaxial temporary LVAD (example – Impella device) directly unloads the left ventricle, but cannot be used in the setting of a mechanical aortic valve. TandemHeart is also a consideration (inflow cannula placed across the interatrial septum in the left atrium) to unload the LV, but does not improve flow across the aortic valve so can lead to thrombus if a mechanical valve is present. Intra-aortic balloon counterpulsation using an IABP can be used to decrease afterload on the native heart and increase coronary perfusion, but does not directly unload the left ventricle.
(5) Acute mechanical valve thrombosis can be managed with emergency surgery or with low dose fibrinolytic therapy. Surgery is preferable when operative risk is low and if there are contraindications to fibrinolytic therapy such as prior intracranial hemorrhage or active bleeding.
(6) VA-ECMO can be weaned by slowly decreasing flow rates and assessing native cardiac function, hemodynamic response, and end-organ perfusion with assessments including echocardiography and pulmonary artery catheterization.
Notes - Mechanical Valve Thrombosis
1. What is a unicuspid aortic valve?
Unicuspid aortic valves (UAVs) are rare with an incidence of only 0.02%.There are two types of UAVs. Acommisural UAVs have a single cusp with a stenotic central orifice and rudimentary commissures that do not divide the valve (pin-hole shaped), and are usually complicated by severe stenosis in early childhood. Unicommisural UAVs are composed of a single cusp with a single commissural attachment to the aortic wall and an elongated orifice (slit-like orifice), which has a less aggressive course and is generally discovered in adulthood.Aortic stenosis is almost universal among UAVs, present with or without aortic regurgitation in 92% of cases. Some series have shown 14% of cases with concurrent aortopathy.UAVs may be associated with congenital abnormalities likes anomalous coronaries, PDA, VSD and coarctation.
2. How do we assess for aortic prosthetic valve stenosis?
Assessment for mechanical valve stenosis involves different echocardiographic parameters than when evaluating a native valve. Doppler velocity index (DVI) is the dimensionless index with LVOT VTI/AV VTI, with severe stenosis suggested by a ratio of 100msec (it takes longer to gush through a more stenotic valve). Effective orifice area (EOA) 0.8cm2), presence of LA thrombus or concomitant CAD in need of revascularization, presence of other valve disease, and presence of possible pannus (which would not respond to fibrinolysis).
6. What is the approach to weaning VA-ECMO?
Assessment of echocardiographic features, hemodynamics, and end-organ perfusion is essential for a successful VA-ECMO wean. First a turndown of the circuit is performed where the ECMO flow is decreased in a protocolized fashion. This should reduce afterload and therefore increase LV contractile reserve, as well as increase preload with return of flow through the ventricles. With these changes, successful hemodynamic parameters to look for are stable cardiac index, central venous pressure, pulmonary arterial pressures, and systemic blood pressures. Successful echocardiographic parameters include an increase in LVEF 20-25%, aortic VTI ≥10 cm, lateral mitral annulus peak systolic velocity ≥6 cm/s,