Residency · Residency · Cardiothoracic Surgery
Right Ventricular Failure After LVAD Implantation
Introduction
Right ventricular failure (RVF) is one of the most serious complications following left ventricular assist device implantation, occurring in 20-40% of patients depending on the definition used. It contributes significantly to early mortality, prolonged intensive care stays, and end-organ dysfunction. Understanding the pathophysiology, prediction, prevention, and management of post-LVAD RVF is essential for the cardiothoracic surgeon.
Pathophysiology
Mechanisms of RV Failure After LVAD
Several interrelated mechanisms contribute to RV failure after LVAD implantation. Interventricular dependence plays a central role: LVAD unloading shifts the interventricular septum leftward, reducing the septal contribution to RV contraction. The enhanced LV output produced by the LVAD simultaneously increases venous return and preload to an already compromised RV. The leftward septal shift also alters RV geometry from its normal crescent shape to a more circular configuration, impairing contractile efficiency. Perioperative factors including cardiopulmonary bypass, blood product transfusion, and the systemic inflammatory response further contribute to RV dysfunction. Pre-existing subclinical RV impairment may be unmasked by the LVAD-induced hemodynamic changes, and reactive pulmonary hypertension from chronic left heart failure may not immediately resolve.
Hemodynamic Manifestations
The hemodynamic picture of post-LVAD RVF includes elevated central venous pressure (CVP greater than 16 mmHg) with decreased LVAD flows, a low cardiac index despite adequate LVAD function, and end-organ dysfunction manifested as hepatic congestion, renal insufficiency, and gut edema.
Preoperative Prediction
Clinical Risk Factors
Key risk factors for post-LVAD RVF include pre-existing RV dysfunction on echocardiography (TAPSE less than 7.5 mm or RV fractional area change less than 25%), elevated right atrial pressure (RAP greater than 15 mmHg) or an RAP/PCWP ratio exceeding 0.63, severe tricuspid regurgitation, need for preoperative mechanical ventilation or inotropic support, elevated bilirubin, creatinine, or AST indicating end-organ congestion, female sex, and non-ischemic etiology.
Prediction Scores
Several scoring systems have been developed to predict RVF risk. The Michigan RVF Risk Score incorporates vasopressor use, AST, bilirubin, and creatinine. The EUROMACS-RHF score is a validated European registry-based prediction model. The Penn RVF score uses hemodynamic and laboratory parameters. No single score perfectly predicts RVF, and clinical judgment integrating multiple parameters remains essential.
| Prediction Score | Key Variables | Notes |
|---|---|---|
| Michigan RVF Risk Score | Vasopressor use, AST, bilirubin, creatinine | Widely used; validated in continuous-flow LVAD |
| EUROMACS-RHF | Registry-based multivariable model | European registry validation |
| Penn RVF Score | Hemodynamic and laboratory parameters | Incorporates RAP/PCWP ratio |
Key Risk Factors for Post-LVAD RVF
| Category | Risk Factor | Threshold / Detail |
|---|---|---|
| Echocardiographic | TAPSE | < 7.5 mm |
| Echocardiographic | RV fractional area change | < 25% |
| Echocardiographic | RV free wall strain | Worse than -9.6% |
| Echocardiographic | Tricuspid regurgitation | Severe |
| Hemodynamic | RAP | > 15 mmHg |
| Hemodynamic | RAP/PCWP ratio | > 0.63 |
| Laboratory | Bilirubin, creatinine, AST | Elevated (end-organ congestion) |
| Clinical | Preoperative ventilation or inotropes | Present |
| Demographic | Sex | Female |
| Demographic | Etiology | Non-ischemic |
Imaging Predictors
Echocardiographic assessment of RV size, function, and tricuspid regurgitation severity provides valuable prognostic information. RV strain analysis by speckle-tracking echocardiography (with RV free wall strain worse than -9.6% predicting RVF) adds incremental value. Cardiac MRI offers volumetric RV assessment when available preoperatively.
Prevention Strategies
Preoperative Optimization
Prevention begins with aggressive diuresis and decongestion to reduce RV preload, optimization of pulmonary vascular resistance with pulmonary vasodilators, and improvement of nutritional status with correction of coagulopathy before surgery. In selected cases, temporary mechanical support with ECMO or Impella RP may allow end-organ recovery before LVAD implantation.
Intraoperative Techniques
During surgery, prolonged cardiopulmonary bypass time should be avoided, blood product transfusion and the inflammatory response should be minimized, and meticulous hemostasis should be ensured to reduce the risk of re-exploration. Concurrent tricuspid valve repair when moderate or greater tricuspid regurgitation is present is increasingly practiced, though it remains somewhat controversial. Optimization of LVAD inflow cannula position is important to avoid excessive septal shift.
Management of Established RV Failure
Medical Management
Volume optimization is critical, as the RV is preload-sensitive; the target CVP is 8-12 mmHg with careful diuresis. Milrinone is the preferred inotrope because it reduces pulmonary vascular resistance while augmenting RV contractility, though dobutamine or epinephrine may also be used. Pulmonary vasodilators including inhaled nitric oxide (20-40 ppm), inhaled epoprostenol, or sildenafil help reduce RV afterload. Vasopressors such as norepinephrine or vasopressin maintain systemic perfusion without increasing PVR. Hypoxia, hypercarbia, and acidosis must be avoided as they exacerbate pulmonary vasoconstriction, and ventilator settings should be optimized to minimize intrathoracic pressure.
Temporary Mechanical RV Support
When medical management is insufficient, mechanical support options include the Impella RP (a percutaneous microaxial pump from the femoral vein to the pulmonary artery providing up to 4 L/min), the Protek Duo (a dual-lumen cannula via the internal jugular vein with an extracorporeal centrifugal pump), a surgical RVAD (direct cannulation of the RA and PA with a centrifugal pump offering the highest flow capability), and VA ECMO for biventricular support when RVF is severe or biventricular failure is present.
| RV Support Device | Access | Flow | Key Advantage | Key Limitation |
|---|---|---|---|---|
| Impella RP | Percutaneous femoral vein to PA | Up to 4 L/min | Percutaneous; rapid deployment | Limited flow; position-sensitive |
| Protek Duo | IJ vein (dual-lumen) + extracorporeal pump | Up to 4.5 L/min | Single venous access; allows ambulation | Requires fluoroscopy for placement |
| Surgical RVAD | RA + PA cannulation; centrifugal pump | Up to 6-8 L/min | Highest flow capability | Requires surgical placement |
| VA ECMO | Femoral or central cannulation | Up to 6-7 L/min | Biventricular + respiratory support | LV distension; does not selectively unload RV |
Duration and Weaning
Temporary RV support is typically maintained for 7-14 days. Support is weaned gradually while monitoring hemodynamics and echocardiographic RV function. Failure to wean may necessitate conversion to biventricular assist device support or urgent transplant evaluation.
Outcomes
Early RVF requiring RVAD support carries a 30-day mortality of 30-50%. Late RVF, occurring after initial recovery, is often precipitated by infection, arrhythmia, or volume overload. Patients who recover from RVF and survive to discharge have reasonable long-term outcomes.
Key Clinical Pearls
Preoperative identification of RV failure risk using multimodal assessment (hemodynamics, echocardiography, laboratory values, and clinical scores) is critical for surgical planning. Leftward septal shift is the hallmark mechanism, and LVAD speed adjustments to reduce septal bowing can improve RV function. Milrinone is the first-line inotrope for post-LVAD RVF due to its dual inotropic and pulmonary vasodilatory effects. Early deployment of temporary RV mechanical support improves outcomes compared to delayed rescue. Concurrent tricuspid valve repair at LVAD implantation should be strongly considered in patients with significant tricuspid regurgitation.
References
- Kormos RL, Teuteberg JJ, Pagani FD, et al. Right ventricular failure in patients with the HeartMate II continuous-flow left ventricular assist device. J Thorac Cardiovasc Surg. 2010;139(5):1316-1324.
- Lampert BC, Teuteberg JJ. Right ventricular failure after left ventricular assist devices. J Heart Lung Transplant. 2015;34(9):1123-1130.
- Kapur NK, Esposito ML, Bader Y, et al. Mechanical circulatory support devices for acute right ventricular failure. Circulation. 2017;136(3):314-326.
- Soliman OII, Akin S, Muslem R, et al. Derivation and validation of a novel right-sided heart failure model after implantation of continuous flow left ventricular assist devices. Circulation. 2018;137(8):891-906.