Cardiac assist devices are a boon to patients with cardiac disorders. The various uses to which they are subjected to and the functioning of these mechanical pumps are explained below. The different types of these devices and the complications that can crop up during and after the implant, compute the core of this synopsis.
Cardiac assist devices or ventricular assist devices are mechanical pumps which work in coordination with the heart and helps in improving the blood flow throughout the body. They can be categorized depending on the ventricles (chambers of the heart) they are designed for. Thus they can be divided into Left ventricular assist devices (LVAD), Right ventricular assist devices (RVAD) and Biventricular assist devices (BiVAD).
All Cardiac assist devices help to bridge a critical gap in time, when a person is anxiously waiting for a donor heart. They are used either on a short term or a long term basis or both. Short term use of the device occurs in patients recovering from heart attacks and heart surgeries. Longer term usage occurs when a cardiac assist device helps keep a patient alive while waiting for a compatible donor heart.
Functioning of Cardiac Assist Devices
Cardiac assist devices have pumps which are attached to a computerized control panel. They are also connected to an external power source. The pump portion of the ventricular assist device has to be surgically implanted in the body. Earlier devices had small battery packs that had to be carried around in a pouch by the patient. Now-a-days technological advances have lead to the development of devices having a tiny battery which is implanted along with the pump. The newer models are lighter and more portable than their predecessors. A person with the relevant cardiac disorder, who has undergone a device implant can lead a life that is very close to normal.
Types of Cardiac Assist Devices
Depending on the volume of blood carried during the pumping cycle, the pumps used in these cardiac assist devices can be classified into Pulsatile pumps and Continuous Flow pumps. Novacor, HeartMateXVE, C-Pulse, Thoratec PVAD (Paracorporeal Ventricular Assist Device) and IVAD (Implantable Ventricular Assist Device) are some of the pulsatile pumps that have hit the market. The continuous flow pumps use either axial flow pumps or centrifugal pumps. There are various types of cardiac assist devices that use these kinds of pumps. The continuous flow pumps that use an axial flow pump include HeartMateII, HeartMateIII, Jarvik 2000, Micro Med De Bakey VAD etc where as those devices that use a centrifugal motor are Ventri Assist, MTI Heart LVAD, HVAD, DuraHeart etc. Some of the above mentioned devices are yet to start clinical trials. Intra-Aortic Balloon Pumps that include Intra-Aortic Balloon Pump Catheters and Intra-Aortic Balloon Pump Consoles are also widely being used by medical practitioners.
Complications of Cardiac Assist Devices
Since the implantation of the Cardiac Assist Device is done via an open heart surgery, all the complications of the surgery are applicable as side effects. There have been reports of instances where the patient had succumbed to bacterial/fungal infections despite obtaining optimal treatment after the device implant. Broad spectrum antibiotics should be started immediately in patients with this complication. Anticoagulation measures should be undertaken to prevent the blood from clotting while flowing through the tubes which have a non-biological surface. Even though some of the latest devices have come up with biological surfaces within their tubes that eliminates the need for anticoagulants, they should still be monitored for possible infections.
Heart failure is a life threatening condition. It weakens the heart and reduces its efficiency to pump blood. These wonder tools referred to as “Cardiac Assist Devices” are a brain child of the technological advances of the modern era. Despite their complications they are still viewed as the much needed bridge on the road to recovery and as a “life sustainer” while waiting for a compatible donor heart.