BIVAD (Biventricular Assist Device)

A BIVAD (Biventricular Assist Device) is a mechanical heart device that provides support to both the left and right ventricles. The BIVAD is used in patients presenting with biventricular heart failure as a bridge to heart transplant. The BIVAD differs from a left ventricular assist device (LVAD) and right ventricular assist device (RVAD) that provide support to only one ventricle. This paper discusses the BIVAD and its use as a bridge to heart transplant.

What is a Biventricular Assist Device?

A biventricular assist device, also called BIVAD, is a mechanical device that provides circulatory assistance to both the left and right ventricles of the heart. The BIVAD consists of two (2) main parts; the left ventricular assist device (LVAD) and the right ventricular assist device (RVAD). The LVAD and RVAD are connected to each other via tubes that are inserted into the heart to facilitate circulation. The LVAD and RVAD are connected externally to a controller and a power supply.

How Does a Biventricular Assist Device Work?

The LVAD is a mechanical circulatory support device that provides circulation support by assisting the left ventricle in pumping blood to the aorta. The main purpose of the LVAD is to improve systemic circulation by providing support to the left ventricle. The RVAD works similarly to the LVAD by assisting the right ventricle to pump blood into the pulmonary artery. The RVAD improves the pulmonary circulation by helping the right ventricle overcome peripheral pulmonary resistance so that blood can be oxygenated in the lungs. A BIVAD, therefore, provides total circulatory support by assisting both ventricles to pump blood to the lungs and the rest of the body. This is especially important in patients presenting with cardiogenic shock and biventricular failure as it assists them in maintaining adequate systemic perfusion in addition to providing circulatory support.

Biventricular Assist Device As A Bridge To Heart Transplant: Indications

A BIVAD is indicated in patients failing with other forms of mechanical circulatory support presenting with biventricular heart failure or cardiogenic shock. Some of the conditions that may necessitate the use of a BIVAD as a bridge to heart transplant include:

Biventricular Heart Failure

Biventricular heart failure occurs when both the left and right ventricles fail to pump blood adequately to meet the circulatory demands of the body. It may be secondary to cardiomyopathy and ischemic heart disease amongst other heart conditions. A BIVAD may be used as a bridge to heart transplant to provide support to both ventricles in patients presenting with biventricular heart failure.

Cardiogenic Shock

Cardiogenic shock is a clinical syndrome that occurs due to the inability of the heart to pump blood sufficiently to meet the metabolic needs of the body hence decreased tissue perfusion. It may be secondary to cardiomyopathy and myocardial infarction. A BIVAD may be used to provide circulatory support in patients presenting with cardiogenic shock.

Severe Left and Right Ventricular Dysfunction

Severe left and right ventricular dysfunction can be secondary to many cardiovascular conditions including pulmonary hypertension, myocardial infarction, and cardiogenic shock. A BIVAD may be used as a bridge to heart transplant to provide left and right ventricular support when severe dysfunction occurs.

Post-Surgical Heart Failure

Heart failure can develop after heart surgery for example, heart transplant, CABG surgery, and valve repair or replacement surgery. A BIVAD may be used to provide mechanical circulatory support to the right and left ventricles following post-surgical heart failure.

Post-Myocardial Infarction (Heart Attack)

Myocardial infarction can cause complete or partial loss of ventricular function. A BIVAD may be used to provide circulatory support to patients presenting with heart failure following a heart attack.

How Biventricular Assist Device Works As A Bridge To Heart Transplant

A BIVAD works by providing circulatory support to the body while reducing the workload of the heart. It does this by assisting the left and right ventricles to pump blood to the rest of the body. Being a bridge to heart transplant, it provides circulatory support to the body until a donor heart is available. A BIVAD, therefore, works by supporting the circulatory system to ensure that it functions normally while also reducing the workload of the heart. It restores the heart’s output by assisting the left and right ventricles to pump blood to the body.

Restoring Cardiac Output

The LVAD restores cardiac output by assisting the left ventricle to pump blood to the aorta. When the LVAD is used, support is provided to the left ventricle resulting in improved cardiac output hence improved systemic circulation. The RVAD restores cardiac output by assisting the right ventricle to pump blood to the pulmonary artery. In doing so, the right ventricle can overcome peripheral pulmonary resistance hence improved pulmonary circulation.

Improving Organ Perfusion

The increased cardiac output brought about by the BIVAD improves systemic circulation. This, in turn, improves organ perfusion by restoring blood supply to the body organs. The restoration of blood supply to the organs is critical as it prevents damage to body organs such as the brain and kidneys that may occur due to inadequate perfusion.

Stabilizing Hemodynamics

The stabilization of the circulatory system by the BIVAD results in stabile hemodynamics. Improved hemodynamics are critical in patients presenting with cardiogenic shock and biventricular failure. It is through stabile hemodynamics that the functioning of various organs is maintained. Maintained organ function is critical in cardiogenic shock and biventricular failure as it prevents rapid deterioration of organ functionality.

Bridge To Transplant

By stabilizing the circulatory system, BIVAD provides circulatory support to the body. The circulatory support provided by the BIVAD is vital in ensuring that the patient survives until a donor heart is available. A BIVAD, therefore, acts as a bridge to a heart transplant for patients presenting with cardiogenic shock and biventricular failure.

Biventricular Assist Device Surgical Procedure

A surgical procedure is required to implant a BIVAD. The procedure is minimally invasive and is performed by cardiothoracic surgeons. The procedure involves making an incision in the chest to access the heart. The most common incision is the median sternotomy incision. After accessing the heart, the LVAD and RVAD are implanted. The tubes that carry blood from the ventricles are inserted into the left and right ventricles as well as the aorta and pulmonary artery respectively. The tubes are then connected externally to a controller and a power supply. The patient is closely monitored for any complications following the procedure.

Benefits of Biventricular Assist Device As A Bridge To Heart Transplant

Life-Saving Circulatory Support

The BIVAD provides life-saving circulatory support to patients presenting with cardiogenic shock and biventricular failure by assisting the ventricles to pump blood to the rest of the body. The circulatory support provided by the device results in improved tissue perfusion hence improved oxygenation of body tissues and organs.

Improving Organ Perfusion

The life-saving circulatory support provided by the BIVAD improves organ perfusion. The improved perfusion is critical in preventing damage to the vital organs such as the brain and the kidneys that may occur due to inadequate perfusion.

Reducing The Heart’s Work

Assisting the ventricles to pump blood reduces the amount of effort that the heart must exert to pump blood to the rest of the body. Reduction in the workload of the heart, together with the improvement of its pumping action, results in the improvement of the function of the heart. Improvement in the function of the heart can be achieved even in the most severely ill patients.

Bridge To Recovery Or Heart Transplant

The improvement in heart function brought about by the BIVAD allows partial recovery. The partial recovery may allow the BIVAD to be removed and the patient discharged following appropriate evaluation. Alternatively, the BIVAD may also be used as a bridge to heart transplant when recovery of heart function does not occur. Therefore, the BIVAD is critical in improving the survival rate of patients presenting with cardiogenic shock and biventricular failure.

Minimally Invasive

The BIVAD procedure is minimally invasive. Although the procedure involves open heart surgery, it is much safer than heart transplant surgery. The benefits of the BIVAD procedure outweigh the possible risks and complications.

Risks And Complications Of Using BIVAD

There are several risks and complications associated with the use of the BIVAD. They include infection, thrombosis, embolism, hemolysis, vascular injury, malfunction of the device, and kidney injury to name a few. The following section will discuss these risks and complications in detail.

Infection

The insertion of the BIVAD increases the risk of infections at the site where the device is placed. Moreover, the BIVAD also increases the risk of meningitis.

Thrombosis, Embolism And Hemolysis

The BIVAD increases the risk of developing blood clots, embolism, and hemolysis. The BIVAD may interfere with normal blood circulation resulting in the formation of blood clots in the device. The formation of blood clots may also occur in the heart and the arteries. When this happens, the blood clots can cause obstructions in the heart and/or arteries.

Vascular Injury

The BIVAD procedure increases the risk of vascular injury especially at the site where the device is inserted. Vascular injury can cause many BIVAD-related complications including stroke and excessive internal bleeding.

Malfunction Of The Device

The malfunction of the device is a serious BIVAD-related complication. The malfunction of the BIVAD may occur due to many reasons including faulty device construction or incorrect positioning. Patients who experience malfunctions of the BIVAD often require another surgical procedure to have the device repositioned or replaced.

Kidney Injury

The BIVAD may cause acute kidney injury especially in patients with pre-existing kidney problems. This happens due to a combination of factors including low blood pressure, reduced perfusion, and vascular damage that may occur following the BIVAD procedure.

Bleeding

Use of the BIVAD may result in excessive internal bleeding. Patients who are placed on anti-coagulant medications to prevent the formation of blood clots are at increased risk of bleeding.

Post-BIVAD And Heart Transplant Surgery

When a donor heart becomes available, the patient is scheduled to have a heart transplant surgery where the BIVAD is removed and replaced with the donor heart. The post-BIVAD and heart transplant surgery care focuses mainly on preventing infection and rejection of the transplant. Patients are closely monitored for signs and symptoms of BIVAD-related complications including infection and excessive internal bleeding.

Conclusion

The BIVAD (Biventricular Assist Device) is a mechanical heart device used to provide support to both the left and right ventricles. The BIVAD is indicated in patients failing with other forms of mechanical circulatory support presenting with biventricular heart failure or cardiogenic shock. It may be used as a bridge to heart transplant in selected patients. The above discussion presents the BIVAD and its use as a bridge to heart transplant.