Over the past 30 years, there have been efforts to produce a mechanical device that can replace the human heart. Extracorporeal univentricular and biventricular implantable devices are available, which can support the failing heart following conventional cardiac surgery, or while awaiting transplantation. The number of potential recipients already far exceeds the number of available donor organs, however, and temporary holding measures that increase the size of the recipient pool only increase the number of patients that die awaiting transplantation.
Devices available include:
- Left Ventricular Assist Device (LVAD)
- Right Ventricular Assist Device (RVAD)
- Biventricular Assist Devices (BIVADS)
At present they are used for selected patients as a bridge to transplantation or occasionally to support patients with cardiomyopathy or myocarditis or those who cannot be successfully weaned from cardiopulmonary bypass following conventional cardiac surgical procedures. An LVAD or RVAD is used depending on which ventricle is failing. These devices consist of extracorporeal pumps, which remove blood from the atria bypassing the ventricles, and deliver it to the aorta and pulmonary circulation. The output of each assist device can be gradually reduced if the patient’s heart recovers. Indeed, in some patients, successful weaning from artificial circulatory support has been described. Others have been successfully bridged to cardiac transplantation using an assist device. These devices are, however, expensive. They are associated with numerous complications, which include infection with Aspergillus species, haematological complications and multiple organ failure. It is not yet known whether the devices are sufficiently free of long term complications to be an effective treatment modality.
No comments:
Post a Comment