NPO for at least 8 hours, preoperative echocardiography and cardiac catheterization, cross-matching of blood products, administration of prophylactic antibiotics, anesthesia consultation, and psychological evaluation for mechanical circulatory support.
Immediate transfer to Cardiovascular Intensive Care Unit (CVICU) for hemodynamic monitoring, anticoagulation management, wound care for driveline sites, physical therapy, and multidisciplinary follow-up for device optimization.
Comprehensive Clinical Guide: BiVAD Implantation (Biventricular Assist Device)
1. Introduction and Overview
A Biventricular Assist Device (BiVAD) implantation is a complex, high-acuity surgical procedure designed to provide mechanical circulatory support to both the left and right ventricles of the heart. While Left Ventricular Assist Devices (LVADs) are common for end-stage heart failure, a subset of patients presents with biventricular failure—where both the systemic and pulmonary circulations are compromised. In these instances, a BiVAD is the definitive bridge to decision, bridge to transplant, or, in rare cases, destination therapy.
The procedure involves the surgical placement of two separate mechanical pumps: one to support the left ventricle (pumping oxygenated blood to the body) and one to support the right ventricle (pumping deoxygenated blood to the lungs). This guide serves as an authoritative resource for clinical professionals regarding the mechanical, surgical, and post-operative management of BiVAD patients.
2. Technical Specifications and Mechanisms
BiVADs utilize continuous-flow rotary pump technology. Modern devices are typically centrifugal pumps that rely on magnetic levitation or hydrodynamic bearings to minimize blood trauma (hemolysis).
The Mechanical Architecture
- The Inflow Cannula: Surgically inserted into the ventricular apex.
- The Pump Housing: A magnetically levitated impeller that provides non-pulsatile flow.
- The Outflow Graft: A synthetic vascular prosthesis (usually Dacron) anastomosed to the ascending aorta (for the LVAD component) and the pulmonary artery (for the RVAD component).
- The Driveline: A percutaneous cable that connects the internal pump to the external controller and power source.
Hemodynamic Impact
Unlike the natural heart, which is pulsatile, the BiVAD provides continuous flow. This alters the patient’s clinical presentation, often resulting in a diminished or absent peripheral pulse, requiring the use of a Doppler ultrasound for accurate blood pressure monitoring.
3. Clinical Indications and Usage
BiVAD implantation is reserved for patients with severe biventricular failure who are refractory to maximal medical therapy (inotrope dependence) and intra-aortic balloon pump (IABP) support.
Primary Indications
| Indication | Clinical Context |
|---|---|
| Bridge to Transplant (BTT) | Patients awaiting a donor heart who have developed severe right heart failure. |
| Bridge to Decision (BTD) | Patients with acute cardiogenic shock where long-term prognosis is unknown. |
| Bridge to Recovery (BTR) | Patients with acute myocarditis or postcardiotomy shock who may recover ventricular function. |
| Refractory Cardiogenic Shock | Failure of isolated LVAD support to maintain systemic perfusion. |
Patient Selection Criteria
- Absence of irreversible multi-organ failure.
- Adequate psychosocial support and cognitive capacity to manage the device.
- Absence of severe systemic infection or coagulopathy.
4. Pre-Operative Preparation
The pre-operative phase is a multidisciplinary effort involving cardiac surgery, advanced heart failure cardiology, perfusionists, and critical care nursing.
Clinical Optimization
- Hemodynamic Assessment: Right heart catheterization to determine pulmonary vascular resistance (PVR). High PVR is a significant contraindication, as the RVAD may fail against high pulmonary pressures.
- Imaging: Echocardiography (TTE/TEE) to assess for intracardiac thrombus, valvular pathology, and ventricular size. Cardiac CT is essential for assessing aortic calcification and anatomy.
- Laboratory Screening: Comprehensive coagulation profile, renal function, and hepatic function tests.
- Nutritional Support: Correction of malnutrition, which is common in chronic heart failure, to optimize post-operative wound healing.
5. The Procedure: Step-by-Step
BiVAD implantation is performed via median sternotomy under cardiopulmonary bypass (CPB).
- Sternotomy and Cannulation: Standard median sternotomy is performed. The patient is placed on CPB via aortic and bicaval cannulation.
- LVAD Implantation: The LV apex is cored, and the inflow cannula is secured using a sewing ring. The outflow graft is anastomosed to the ascending aorta.
- RVAD Implantation: The RV apex (or inflow site) is cored, and the RVAD inflow cannula is secured. The outflow graft is anastomosed to the main pulmonary artery.
- De-airing: Rigorous de-airing techniques are employed to prevent embolic stroke.
- Weaning from CPB: The pumps are activated, and the patient is slowly weaned from the heart-lung machine as the BiVAD assumes the workload.
- Driveline Tunneling: The drivelines are tunneled through the abdominal wall to exit the skin, ensuring a long, tortuous path to minimize infection risk.
6. Post-Operative Recovery Protocol
Recovery begins in the Cardiac Intensive Care Unit (CICU).
- Hemodynamic Monitoring: Target Mean Arterial Pressure (MAP) is typically 70–80 mmHg.
- Anticoagulation: Initiation of heparin followed by transition to Warfarin (target INR 2.0–3.0) and antiplatelet therapy (Aspirin).
- Driveline Care: Strict sterile dressing changes to prevent percutaneous site infection, which is the "Achilles heel" of VAD therapy.
- Early Mobilization: Physical therapy begins within 48–72 hours to prevent deconditioning and venous thromboembolism.
7. Risks and Complications
BiVAD therapy carries significant morbidity risks.
Major Complications
- Bleeding: Often related to anticoagulation and acquired von Willebrand syndrome (a common side effect of continuous-flow pumps).
- Infection: Driveline infections or systemic sepsis.
- Thromboembolism: Pump thrombosis or ischemic stroke.
- Right Heart Failure: If the RVAD is insufficient or the pump is malpositioned.
- Neurological Events: Hemorrhagic or ischemic stroke.
Contraindications
- Irreversible end-organ damage (e.g., severe cirrhosis or end-stage renal disease).
- Active, uncontrolled systemic infection.
- Inability to comply with complex anticoagulation regimens.
8. Alternative Treatments
Before proceeding to BiVAD, clinicians must consider:
* Total Artificial Heart (TAH): Used in patients with biventricular failure and severe anatomical abnormalities or ventricular arrhythmias.
* Extracorporeal Membrane Oxygenation (ECMO): A short-term bridge for acute, reversible shock.
* Heart Transplantation: The gold standard, though limited by donor availability.
* Medical Management: Inotrope infusion (Milrinone/Dobutamine), though often insufficient for long-term survival.
9. Frequently Asked Questions (FAQ)
1. How long can a patient live with a BiVAD?
BiVADs are primarily designed as a bridge to transplant. While some patients have lived for several years, the risk of infection and thrombosis increases over time.
2. Can a patient feel their heartbeat with a BiVAD?
Usually, no. Because the flow is continuous, the pulse pressure is often minimal. Patients may not have a palpable pulse.
3. What happens if the power fails?
The external controller has backup batteries. Patients must always carry a "go-bag" with spare batteries and a backup controller.
4. Can a patient take a shower?
With modern equipment and specialized waterproof covers, patients can shower, but they cannot submerge the pump or batteries in water. Swimming is strictly prohibited.
5. Why is the INR monitored so closely?
To balance the risk of stroke (clotting) versus the risk of major bleeding (hemorrhage) due to the mechanical nature of the pump.
6. What is the most common cause of death after BiVAD?
Infection and neurological events (strokes) remain the leading causes of mortality in the post-operative period.
7. Does the BiVAD fix the heart?
In some cases of myocarditis, the heart may "rest" and recover function, allowing for device explantation. However, in chronic heart failure, the heart usually does not recover.
8. Is there a risk of pump thrombosis?
Yes, this is a serious complication. It presents as high power consumption on the controller, hemolysis (dark urine), or symptoms of heart failure.
9. Can the patient drive a car?
Most programs restrict driving due to the risk of the device failing or the patient losing consciousness, though policies vary by center.
10. What is "driveline exit site infection"?
It is an infection where the cable exits the skin. It is treated with aggressive wound care and antibiotics, but if it becomes deep-seated, it may require surgical revision.
10. Conclusion
BiVAD implantation represents the pinnacle of mechanical circulatory support. It is a life-saving intervention for patients who would otherwise succumb to biventricular failure. Success requires not only surgical precision but a robust, long-term commitment from a multidisciplinary team. As technology advances toward smaller, more biocompatible pumps, the outlook for BiVAD patients continues to improve, offering a vital bridge to a new heart or, in specific cases, a sustainable life with mechanical support.
Disclaimer: This guide is for educational purposes for clinical professionals and does not replace institutional protocols or surgical judgment. Always consult the latest device-specific manufacturer guidelines.