For the last 40 years, heart transplantation has been the golden standard therapy for patients who suffer from end stage heart failure, a condition in which the heart is unable to pump the blood to the rest of the body sufficiently.
A clinical study conducted by the Hopkins Division of Cardiac Surgery sets itself apart from other studies done on heart transplantation, as it observed long-term factors that impacted survival rates of patients.
The Hopkins surgical division conducted a 10-year multivariate analysis on post-transplantation patients to identify factors that affected the long-term survival rate of these patients. Their study determined that recipient age, race, ischemic time, donor age and the center volume have significant impact on post-operative survival.
The patient population included those who underwent heart transplantation between 1987 and 1999. There was a positive correlation of increased survival rates with later transplant years, an indication that heart transplantation conditions are gradually improving. In other words, those who underwent surgery in 1999 had a larger chance of surviving than those who underwent surgery in 1987.
As other studies have consistently indicated, the donor recipient age is a principal factor of survival. As age increases, recipients have a larger chance for encountering adverse factors, such as infection or other organ failures. A great number of elder patients experience infections due to the decline in their immune system. They are also increasingly vulnerable to renal failure.
Disparities in survival rates have also been demonstrated between races. White patients constituted a majority of those who survived more than 10 years. Whether this is rooted in biological or socioeconomic differences is not clear. Further research is warranted.
The necessity of mechanical ventilation during the wait for receiving a donor decreased odds for 10-year survival as well. Mechanical ventilation is a method that assists spontaneous breathing.
Frequently, patients with heart failure require mechanical ventilation to maintain sufficient oxygen supply. These patients typically must remain in the hospital for intensive care. This increases the risk for nosocomial infections - infections acquired within the hospital setting - nutritional depletion and generalized deconditioning.
While the recipient's age significantly influences survival rates, the donor's age is also a major factor in predicting long-term survival. Mostly, this is because organ quality is observed declines with age. Older hearts are also more susceptible to longer ischemic time, which is the period of time when the heart is not supplied with oxygen, between its harvest and transplantation. Of course, ischemic time is another variable included in this study, as an increase in ischemic time could greatly affect donor organ quality. Another variable considered in this multivariate study was the center volume, or the frequency of heart transplantation surgeries in each hospital. With increasing surgical experience and resources, and better accommodations for heart transplantation patients, does hospital care have any effect in long-term survival rates? According to data, the threshold value of nine transplantations per year in a hospital seems to have a positive impact on the admitted patient.
Although this was a very elaborate study, there were limitations inherent to any study that examines such multivariate subjects, especially in long-term cases. Limitations include the effect of ventricular assist devices.
Ventricular assist devices (VAD) are devices implanted to directly facilitate the pumping of blood by the heart. Recently, VADs have been a very attractive option for patients who are waiting to be matched with a donor, which may take months. Other variables include the preservation methods of the donor hearts.
This study examined patients who received heart transplantations between 1987 and 1999. Since then, surgical technologies and techniques have improved significantly, as well as our understanding of improving quality of life for patients. These are variables that can be included in future studies that investigate long-term post-transplantation survival rates.