Venoarterial Extracorporeal Membrane Oxygenation to Facilitate Transcutaneous Mitral Valve Replacement in Critical Mitral Stenosis.

Biological mitral valve restenosis after replacement in rheumatic heart disease is a rare complication. This case illustrates venoarterial extracorporeal membrane oxygenation to facilitate transcatheter mitral valve replacement in a patient with suprasystemic pulmonary pressure and cardiogenic shock with multiorgan failure secondary to critical mitral stenosis of a bioprosthetic valve.(Level of Difficulty: Advanced.).

A 39-year-old African-American woman presented to our emergency department with progressive dyspnea over the previous 3 months, lower extremity edema, and a recent syncopal episode. Her medical history included rheumatic heart disease with mitral stenosis, and tricuspid regurgitation after bioprosthetic mitral valve (MV) replacement and tricuspid ring annuloplasty in 2016. An echocardiogram in 2018 showed left ventricular (LV) end-diastolic diameter of 4 cm, and normal functioning MV and tricuspid valve with normal pulmonary pressure. Additional medical history included HIV infection (since 2013) with cluster of differentiation 4-count 1,094 and undetectable viral load (with antiretroviral treatment: elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide fumarate), obesity (body mass index 39 kg/m2), chronic kidney disease stage 3a, tobacco use disorder, and hypertension. Other medications included daily aspirin and valsartan-hydrochlorothiazide.

Learning Objectives

To recognize VA-ECMO as a possible measure to facilitate complex percutaneous valvular interventions in critically ill patients.

To identify the main elements in preplanning for TMVR in an acutely ill patient.

Presentation

On admission, her body mass index was 46 kg/m2, blood pressure 106/64 mm Hg, pulse 96 beats/min, respirations 30/minute, and O2 saturation 100% on room air. She had jugular venous distension to the earlobes, holosystolic and diastolic murmur, bibasilar crackles, cool extremities with 2+ pitting edema to knees, and no neurologic deficits.

Laboratory studies revealed serum creatinine 2.5 mg/dL (baseline 1.3), international normalized ratio 1.7, lactate 4.5 mmol/L, pro-B type natriuretic peptide >5,000 pg/mL, troponin I 0.55 ng/mL, and creatine kinase 164 U/L. An electrocardiogram showed sinus tachycardia with new right bundle branch block.

Question 1: What Is The Differential Diagnosis and What Diagnostic Test Should Be Performed First?

Answer 1

The patients’ history of MV replacement with recent progressive dyspnea, syncope, and multiorgan failure suggest MV degeneration or thrombosis. Pulmonary embolism is possible, though less likely without an apparent trigger. Myocardial dysfunction secondary to ischemia is possible, given her multiple risk factors, but a low troponin and no ischemic changes on electrocardiogram argue against acute ischemia. The first step should be to evaluate the MV and cardiac function with a transthoracic echocardiogram (TTE).

TTE revealed significant right ventricular dilation, severe tricuspid regurgitation, and systolic pulmonary artery pressure (PAP) ∼110 mm Hg. The LV end-diastolic diameter was 2.7 cm, with elevated MV gradient of 26 mm Hg and area of 0.45 cm2 with mild mitral regurgitation (heart rate 97 beats/min) (Figure 1, Supplemental Video 1, Supplemental Video 2). She underwent right heart catheterization with placement of a pulmonary artery catheter, showing right atrial pressure 25 mm Hg, right ventricular pressure 120/25 mm Hg, PAP 120/55/76 mm Hg, and pulmonary capillary wedge pressure 39 mm Hg, with cardiac output 4.2 L/min and cardiac index 1.8 LPM/m2 by the Fick calculation.

Figure 1

Admission Transthoracic Echocardiogram

Echocardiography on admission: left to right, 4-chamber apical view, with dilated RV and decompressed LV. Tricuspid valve jet velocity measured with continuous wave Doppler on 4-chamber apical view. Subcostal view showing dilated IVC with no respiratory variations. Apical 4-chamber view with continuous Doppler to assess mitral valve gradient. IVC = inferior vena cava; LV = left ventricle; RV = right ventricle; TTE = transthoracic echocardiogram.

Question 2: What Is The Likely Cause Of The Pulmonary Hypertension, And How Should The High Transpulmonary (37 mm Hg) And Diastolic Gradients (16 mm Hg) Be Interpreted?

Answer 2

Severe pulmonary hypertension (PH) was likely a consequence of both elevated left atrial pressure due to severe mitral stenosis (type 2 PH) and intrinsic pulmonary component, evident from increased transpulmonary and diastolic gradients (e.g., type 1 due to HIV); however, a reactive component to presumably long-standing elevated left atrial pressures was considered the likely cause. Despite the possibility of a type 1 PH component, a trial of pulmonary vasodilators could have increased flow to the highly congested left atrium, aggravating the transvalvular gradient further; therefore, it was not given. The lack of severe lung disease or past thromboembolism made type 3 and 4 PH, respectively, less likely as a cause of the severe PH.

The patient experienced cardiogenic shock with oliguria and was given dobutamine, but she remained anuric and dyspneic, and she had recurrent syncopal episodes with minimal effort (e.g., sitting in bed).

Question 3: What are The Indications for Mechanical Circulatory Support and What are The Relevant Clinical Options in This Case Vignette?

Answer 3

Progressive cardiogenic shock with end-organ damage despite inotropic support, secondary to low-output state and volume overload, were the indications for mechanical circulatory support. A multidisciplinary team deemed any surgical intervention prohibitive and any transcutaneous MV (TMV) intervention or replacement (TMVR) too high risk without prior hemodynamic stabilization. Underfilling of the LV and severe PH would not have been corrected by percutaneous right-sided support alone. Biventricular support with a right ventricular assist device in combination with a left ventricular assist device was deemed technically challenging and of unclear benefit, leaving a percutaneous centrifugal left ventricular device or venoarterial extracorporeal membrane oxygenation (VA-ECMO) as viable options. Of these, VA-ECMO with local anesthesia and partial sedation was deemed safest. Shortly after VA-ECMO cannulation, the patient’s urine output increased considerably (3.8 L over 12 hours), and she experienced substantial respiratory improvement.

Question 4: How To Plan for Tmvr in A Critically Ill Patient?

Answer 4

The patient’s condition precluded computed tomography angiography in a TMVR protocol or transesophageal echocardiogram before VA-ECMO; thus, the planning for the procedure (in anticipation of which VA-ECMO was initiated) was performed with the available imaging and clinical data, with expectation of a transesophageal echocardiogram–guided TMVR.

As a valve-in-valve is deployed, the surgical bio-prosthetic anterior leaflet is forced into a fixed opening position towards the interventricular septum by the newly implanted valve frame, elongating and restricting the left ventricular outflow tract (“neo-LVOT”) with a potential significant reduction of systolic blood outflow and devastating hemodynamic repercussions, with mortality rates of up to 62% (Figure 2). We anticipated the need for a tip-to-base, midline, radiofrequency-mediated laceration of the anterior bioprosthetic mitral leaflet to prevent outflow obstruction (LAMPOON) procedure to avoid clinically significant LVOT obstruction, based on preprocedural TTE. The TTE predicted a narrowed neo-LVOT of <200 mm2 and an increased risk of LVOT obstruction upon TMVR, making a preemptive leaflet splitting mandatory. A LAMPOON was performed (Figure 3, Video 3). Subsequently, the patient underwent a successful TMVR with a 29-mm valve in valve using cerebral embolic protection (Video 4). There was a trace paravalvular leak at the end of the case, with a transmitral gradient of 3 mm Hg (Figure 4, Video 5) and absence of LVOT obstruction. The iatrogenic atrial septal defect was subsequently closed to prevent right-to-left shunting in the presence of severe PH. VA-ECMO was decannulated on the second day after TMVR, a transesophageal echocardiogram showed an MV gradient of 8 mm Hg, and the patient was extubated on hospital day 12 (Table 1). A TTE on day 19 showed no MV regurgitation, a mean gradient of 4.9 mm Hg, normal right atrial pressure, and systolic PAP ∼25 mm Hg (Figure 5, Video 6).

Figure 2

Mitral Bioprosthetic Valve Before and After LAMPOON

3D echocardiographic evidence of the mitral bioprosthetic valve before (A) and after (B) anterior leaflet laceration using LAMPOON. Arrows indicate the postlaceration splay. LAMPOON = laceration of the anterior bioprosthetic mitral leaflet to prevent outflow obstruction.

Figure 3

Mitral Bioprosthetic Valve Before and After LAMPOON

Echocardiographic demonstration of systolic blood flow through the THV cells into the LVOT. (A) Mitral THV opening in diastole. (B) Mitral THV closure in systole with a small residual outflow tract (star). Bioprosthetic commissure post extending into the LVOT can also be appreciated (white arrow). (C) Adequate systolic blood flow through the THV cells is evident (red arrow). Atrial septal closure device (blue arrows) and THV (green arrows) in (D) echocardiography and (E) fluoroscopy. LVOT = left ventricular outflow tract; THV = transcatheter heart valve.

Figure 4

Blood Flow in the LV

Blood flow into the left ventricle in diastole (A) and into the aorta in systole (B). A THV implantation forces the anterior leaflet into opening position, thereby restricting and elongating the LVOT (“neo-LVOT”) with expected reduction of outflow (C). Leaflet splitting with LAMPOON ensures adequate outflow through the THV cells (D). LAMPOON = laceration of the anterior bioprosthetic mitral leaflet to prevent outflow obstruction; LVOT = left ventricular outflow tract; THV = Transcatheter heart valve.

Table 1

Hemodynamic Measures Throughout Hospitalization

	RHC, HD 3 (Dobutamine 2.5 μg/kg/min)	Pre-TMVR, HD 7 (Dobutamine 4 μg/kg/min, on ECMO Flow 3.5 LPM With ∼90 cc/min of DPC Flow)	Post-TMVR, HD 8 (Dobutamine 4 μg/kg/min, Norepinephrine 8 μg/min on ECMO Flow 3.3 LPM)	Post ECMO Decannulation, HD 11 (Milrinone 0.25 μg/kg/min, Vasopressin 0.03 U/min)
Blood pressure, mm Hg	90/59/69	115/69/79	106/59/69	123/63/82
Heart rate, beats/min	88	91	92	64
Right atria, mean, mm Hg	25 with TR pattern	15	12	11
Right ventricle	120/mm Hg	-	-	-
Pulmonary artery, mm Hg	120/55/76	118/65/84	58/32/41	65/25/39
Pulmonary capillary wedge pressure, mm Hg	39	Unable to wedge	Unable to wedge	Unable to wedge
Systemic vascular resistance, dynes/s/cm−5	838	1600	930	676
Pulmonary artery saturation, %	36.8	36	73	73
Pulse oxygen	100% on 4L NC	100%, intubated FiO2 35%	100%, intubated FiO2 40%	100%, intubated FiO2 35%
Hemoglobin, g/dl	8.3	9.2	10.4	9.1
Fick cardiac output, L/min	4.2	4.0	4.9	8.4
Fick cardiac index, L/min/m2	1.8	1.6	3.3	3.8

DPC = distal perfusion catheter; ECMO = extracorporeal membrane oxygenation; HD = hospital day; RHC = right heart catheterization; TMVR = transcatheter mitral valve replacement.

Figure 5

Post-TMVR TTE

Echocardiography before (left) and after (right) TMVR showing increased LV size and improvement in RV dilation (A). Improved estimated systolic PA pressure with reduction of TR velocity to 204 cm/s (B). Marked improvement in right atrial pressure as shown in a subcostal view of compressible and nondistended inferior vena cava (C). PA = pulmonary artery; LV = left ventricle; RV = right ventricle; TMVR = transcutaneous mitral valve replacement; TR = tricuspid regurgitation.

Question 5: What is the Anticipated Hemodynamic Course After Tmvr In Patients With Severe ph and Low LV Filling? What Parameters Should be Monitored?

Answer 5

The main parameters to monitor are end-organ function and resolution of PH with recovery of LV filling and function. An additional aspect is potential right-to-left shunting (secondary to severely high pulmonary pressures and low left atrial pressure after valve-in-valve) through the atrial septal defect formed during the TMVR procedure. Hence, a closure device was implanted to avoid this complication, and transesophageal echocardiogram immediately after the procedure as well as serial TTE excluded any shunts. After the successful procedure, the patient’s left atrial pressures declined considerably, with a more gradual decrease of pulmonary pressures, possibly explained by a “reactive” component of PH that was the cause of the increased transpulmonary and diastolic gradient. This gradual decrease has been described in both open MV replacements, valvuloplasty and clip, with an initial decrease in PAP by 44%, and 52% at 1 year., We also observed that full LV recovery required multiple days until an increase in LV end-diastolic diameter was visible on TTE, perhaps as a result of prolonged underfilling. This case is, however, unique in that the patient’s PH resolved rapidly, despite extremely elevated systolic PAP, transpulmonary and diastolic gradient observed initially, all risk factors for persistent PH. This degree of reversibility is specific to treating mitral stenosis, suggesting that it is never too late to treat. Further studies are needed to elucidate the hemodynamic or clinical factors that may predict PH reversal in percutaneous mitral interventions.

It is concluded that VA-ECMO can be used to support complex transcatheter procedures such as LAMPOON followed by TMVR in critically ill patients. Preprocedural planning with anticipation of neo-LVOT narrowing, and performing the LAMPOON maneuver if indicated, are of great importance for a successful intervention.

Funding Support and Author Disclosures

Dr Latib is a consultant for and on the advisory boards of Edwards Lifesciences, Medtronic, and Abbott Vascular. Dr Jorde is a consultant for Abbott. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.