What Is A Left Ventricular Assist Device (LVAD)?

Heart failure is one of the main causes of death. The heart muscle cannot pump the blood around the body effectively which can result in the patient being unable to complete everyday tasks. An LVAD is a device that can be implanted into the chest to regain heart function by artificially enhancing the pumping of blood. Once the blood flow to the organs is regained, the patient will have reduced symptoms associated with heart failure. LVAD is used in patients who are awaiting heart transplants. The downside of LVAD is that if the patient's symptoms improve, then they may end up further down the transplant list. Frequent charging is also the main disadvantage of an LVAD.

Anatomy and physiology of the heart

The heart is made up of three layers the epicardium, myocardium, and endocardium. The pericardium surrounds the heart. The heart is split into four chambers; two atria, and two ventricles.  There are two valves, the mitral valve that separates the left atria and left ventricle, and the tricuspid valve that separates the right atria and right ventricle. The left ventricle pumps blood to the body. As such, if the pressure that the blood is pumped is not high enough, then this blood can regurgitate backward causing less blood to be delivered to the body, resulting in the organs of the body being starved of oxygen.  Left ventricular failure results in heart failure.

Causes and risk factors

Cardiac arrest (Heart attack) - Cardiac arrest can lead to permanent damage to the heart muscle resulting in heart failure 

Dilated  Cardiomyopathy - This condition causes the walls of the heart to become thin, which can prevent good blood circulation. This can be caused by a genetic mutation or by uncontrolled high blood pressure. 

Transthyretin amyloidosis - The liver produces mutated transthyretin proteins. This results in a build-up of these proteins within the left ventricle of the heart. They prevent the blood from being pumped effectively.² The life expectancy with this condition is usually longer than standard amyloidosis, usually decades rather than years. The main reason that transthyretin amyloidosis causes heart failure is due to a thickening of the left ventricular wall.⁴

Patient eligibility criteria

Patients need to meet the criteria before they will be fitted with an LVAD. This includes the fact that the patient must have significant discomfort when completing day-to-day tasks, or be unable to complete day-to-day tasks at all. More information on patient eligibility criteria can be found here. 

Indications for LVADs

When is LVAD used?

A “bridge to transplant” essentially means providing temporary support for patients awaiting heart transplantation, who are currently experiencing heart failure. LVAD may also be used as a long-term solution for patients ineligible for heart transplantation. Patients may be ineligible for heart transplants due to lifestyle factors such as smoking, or because they are of an increased age.  LVAD is used to improve the quality of life and survival rates among  people living with heart failure.⁵

Picture taken from https://commons.wikimedia.org/wiki/Category:Ventricular_Assist_Device#/media/File:LVAD_CDC_Gordon.gif

Author of picture: By Steven M. Gordon - United States Centers for Disease Control, Public Domain, https://commons.wikimedia.org/w/index.php?curid=8350888

Complications and challenges 

There is a great risk of infection with bacteria Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus spp., also being common causes at the surgical site.⁹ There are a large number of strategies for the prevention and management of infection, such as special kits that are placed over the device when showering, and teaching patients how to change their dressings. Device malfunctions and common technical issues can be a challenge when using an LVAD, for example, if the device gets wet, it can stop working. Maintenance and troubleshooting strategies can include: trying to work out how long the battery life lasts, and how to work out any problems with the software as they arise.⁸

Technological advancements

Smaller and more portable LVADs will have an impact on patient mobility and quality of life. Remote Monitoring of Real-time data collection and analysis can allow the patient to monitor the efficacy of the device. Thus enhancing patient care and reducing hospital visits. Artificial Intelligence Integration and AI-driven algorithms for personalised patient management can provide predictive analytics for the early detection of complications.⁵

Axial flow pumps and centrifugal pumps are a 2nd generation type of LVAD. These types of pumps can generate a higher flow rate of blood at a lower pressure which is advantageous in a heart pump the first generation LVAD’s. In the future, further work on this theory could provide better outcomes for high-flow and low-pressure pumps.³ Axial flow pumps have a single rotating piece called an impeller which is held in place by bearings. The pump floats off the bearings and then is concealed within a solid outer box. There is then a continuous flow that goes one way across the axis of rotation.⁵

Complications 

Bleeding and thrombosis are other main complications. This is prevented with anticoagulation medication. It is important to balance the risks of bleeding and thrombosis, with the effective working of the LVAD pump. If the blood is too thick this can cause problems for the device, however, if the blood is too thin this can cause problems with bleeding around the site of the device.²

Infection at the site on the incision

With any major operation, the risk of infection needs to be managed and effective antibiotic treatment administered if the patient develops any subsequent infections after surgery. Viral infections may lead to myocarditis. Viral infections can lead to the immune system attacking the heart. This makes the muscles of the heart weaker and reduces blood pressure which causes a reduction in the heart’s ability to pump blood to the body.⁹

Problems with scar tissue and adhesions can also be a problem, especially if the patient acquires a large amount of scar tissue and then goes on to have a heart transplant. This makes it harder for the surgeons to remove the LVAD and place the donor's heart.¹⁰

Patient outcomes and quality of life 

Survival rates 

The survival rates for patients with an LVAD will vary considerably from patient to patient and will be dependent on factors such as how well the body recovers, and potential infections that may arise. About “80–85% of patients are alive a year after having an LVAD placed and 70–75% of patients are alive for 2 years with an LVAD.” according to the University of Utah.⁶

Psychological and social impacts of LVAD therapy

Living with an LVAD can help improve psychological and social problems by allowing the patient to be more active and spend longer on their feet. However, the downsides of being constrained by making sure they can charge the device frequently can feel constraining. There is also the issue of not being able to get the device wet, which can limit choices such as swimming and other sports involving water. Contact sports are also prohibited because of the risk of damaging the pump or electronic charging components. Click here to see a video about a patient with LVAD and how the device changed her life. Patients with LVAD can also struggle with the adjustment to having an LVAD with increased incidence of anxiety and problems with both endocrine (hormone) and metabolic (turning food into energy) systems.⁷

Conclusion 

In conclusion, the LVAD is an invaluable piece of technology that can buy people with heart failure time before a suitable heart transplant can be performed. It can also be used as a long-term option for people who are not viable for a heart transplant. Survival times vary but some patients have been known to live 13 years after the LVAD was placed, which is compared to a 12-month survival rate for patients without LVAD. As technology improves and devices get smaller and the charging time reduces this will only increase the patient’s quality of life. Hopefully in the future waterproof devices can be manufactured to allow patients to have the ability to swim or bathe without worrying about getting the device wet. In all, the LVAD is a great piece of technology that can be used to help people afflicted with heart failure.¹¹