About Heart Transplant or Cardiac TransplantDecember 21, 2008
Cardiac transplant; Transplant – heart
Heart transplantation is a surgical procedure to remove a damaged or diseased heart and replace it with a healthy donor heart.
Heart transplant is the fourth most common transplant operation in the U.S., with over 2,200 cases per year. Cornea, kidney and liver transplants are the most common. A healthy heart is obtained from a donor who is brain dead but on life-support. The healthy heart is put into a special solution that preserves the organ.
The patient is put into a deep sleep with general anesthesia, and a cut is made through the breast bone. The patient’s blood is circulated through a heart-lung bypass machine to keep the blood oxygen-rich. The patient’s diseased heart is removed and the donor heart is stitched in place. The heart-lung machine is disconnected. Blood flows through the transplanted heart.
A heart transplant may be recommended for:
Heart failure caused by
* Coronary artery disease
* Cardiomyopathy (disease of the heart muscle)
* Heart valve disease with congestive heart failure
* Severe heart disease present at birth
* Life-threatening abnormal heart beats that do not respond to other therapy
Heart transplant surgery is not recommended for patients who have:
* Kidney, lung, or liver disease
* Insulin-dependent diabetes with poor function of other organs
* Other types of blood vessel disease of the neck and leg
* Other life-threatening diseases
Risks for any anesthesia are:
* Reactions to medications
* Problems breathing
Risks for any surgery are:
Heart transplants carry major risks. There is a greater risk of infection because of the drugs that must be taken to prevent transplant rejection. Call your doctor if there are signs of infection (redness, drainage, fever) or if there is a general worsening of health.
Expectations after surgery
Heart transplant prolongs the life of a patient who would otherwise die. About 80% of heart transplants are alive 2 years after the operation. The main problem, as with other transplants, is graft rejection. If rejection can be controlled, the patient’s survival can be increased to over 10 years.
Drugs that prevent transplant rejection must be taken for the rest of the patient’s life. Normal activities can resume as soon as the patient feels well enough and after consulting with the doctor. However, vigorous physical activities should be avoided.
The major problems are the same for all major organ transplants:
* Finding a donor
* Fighting the rejection effect
* The cost of the surgery
* Avoiding infection
* Avoiding blocked blood vessels in the transplanted organ
Finding a donor can be difficult. In heart transplantation, the healthy heart must come from a person who recently died or is on life-support and is brain dead. This is different than a kidney transplant, because a kidney may be donated by a living person.
Timing is very important because there is no good way to keep a donor heart alive for long periods of time. A person in need of a heart transplant may be kept alive on artificial heart devices for longer and longer periods of time. However, artificial hearts also have major risks. While some of these devices are fully approved, others are still considered experimental.
Fighting rejection is an ongoing process. The body’s immune system considers the transplanted organ an infection and fights it. For this reason, organ transplant patients must take drugs such as cyclosporine and corticosteroids that suppress the body’s immune response. The downside of these drugs is that they weaken the body’s natural defense against infection.
The recovery period is about 6 weeks. The patient must move the legs often to reduce the risk of deep venous thrombosis. The stitches or clips are removed about 1 week after surgery.
There are several mentions of heart transplantation in ancient mythology and biblical reference, but it was the pioneering work of Alexis Carrel at the beginning of the 20th century that made organ transplants a real possibility.
The next reported heart transplantations were those of Mann at the Mayo Clinic in 1933. These dog heart transplants were able to function until the onset of rejection at eight days.
After these experiments, there was a 20-year period without progress until the late 1940s. S.V.P. Demikhov, a Russian surgeon, then initiated a series of ingenious experiments on the technical feasibility of both intra thoracic heart transplants as well as heart lung transplantation, although his work was not reported in the West until 1962.
With the advent of techniques for successful heart surgery in the 1950s, major attention was finally given to heart transplantation.
Various experiments using either hypothermia (low temperature) and circulatory arrest or the early cardiopulmonary bypass machines permitted a number of ingenious laboratory studies to be performed.
The currently-used surgical technique for heart transplantation originated with the work of Lower & Shumway in 1959, but the first human heart transplantation was performed by Christian Barnard in Cape town, South Africa, in December 1967.
This transplant triggered a great amount of interest at other centres around the world, with 170 transplants by 65 surgical teams performed between December 1967 and March 1971. However, with only 15 per cent of patients surviving a year after the procedure, enthusiasm for heart transplantation waned by the end of 1971.
Widespread application of heart transplantation depended on development of better immunosuppressive therapy. This came with the discovery of the drug Cyclosporin.
The rapid development and introduction of this compound to clinical transplantation resulted in superior results. Later on many drugs and methods were used in heart transplantation, including FK506, ATG, OKT3, MMS and body radiation.
Why do I need a heart transplant?
Candidates for heart transplantation should have terminal heart failure, and a life expectancy of less than 12 months.
Sometimes the heart is irreversibly damaged by long-lasting heart disease or viral infection. In general, indications for heart transplantation are:
- Cardiomyopathy (acute or chronic disease of the heart muscle)
- Coronary artery disease
- Valvuler heart disease
- Complex forms of congenital heart defects
Can anybody go through heart transplantation?
No. The criteria for recipient selection according to Papworth Hospital in Cambridge is as following:
- End-stage heart disease with life expectancy limited to 6-12 months.
- Age of less than 55 years for coronary arteries disease; less than 60 years for cardiomyopathy
- Absence of irreversible hepatic or renal failure
- Absence of active infection
- Absence of recent pulmonary infection
- Psychosocial stability
- There is no lower age limit to heart transplantation
When can’t you do a heart transplant?
There are absolute and relative contraindications to heart transplantation.
- Absolute contraindications:
- active infection
- untreated malignancy
- coexisting systemic illness likely to limit survival
- severe and irreversible major organ dysfunction
- fixed elevated pulmonary vascular resistance
- Relative contraindications:
- advanced age
- recent or unresolved pulmonary infection
- active peptic ulceration
- marked peripheral or cerebrovascular disease
- mental illness
How long can I expect to live after heart transplantation?
The longest survival after heart transplantation is 24 years. The survival rate has improved dramatically during the last 10 years.
Heart transplants performed with 1, 5, and 10 year survival figures are now approaching 90%, 70%, and 50%, respectively.
What are the criteria in donor selection?
Donor selection is critically important if early postoperative problems are to be avoided.
Potential donors will be certified as brain dead if two separate brain stem function tests show no activity. Most donors have had head injuries or an intra cerebral bleeding, gunshot wound, brain tumour, or liver failure.
Ideal criteria for the donor include the following:
- age (<45 years for male, <50 years for females)
- weight (within 25 per cent of the recipient’s weight)
- ABO compatibility
- no evidence of heart injury (normal ECG, normal chest X-ray)
- no evidence of active infection (HIV, hepatitis B, or bacterial)
- no malignancy apart from brain tumours.
What are the most common complications expected after heart transplantation?
There are many complications associated with heart surgery in general, but the most important complications in heart transplantation are divided into two groups:
- Early complications:
- donor organ dysfunction
- acute rejection
- renal failure
- arrhythmia (abnormal heart beat)
- Late complications:
- accelerated coronary athrosclerosis (coronary disease)
- chronic rejection
- hypertension (high blood pressure)
- malignancy (cancer)
What are the causes of donor heart dysfunction?
Ventricular dysfunction is often present as a result of the adverse effects of brain death on the heart; and the ischemic period during storage and transplant.
Right ventricular failure may occur because the unprepared right ventricle of the donor has to perform work against the recipient’s pulmonary vascular resistance which may be elevated. Lack of reflex sympathetic enervation may diminish the heart ability to compensate for any reduction in function.
What are the causes of renal failure after heart transplantation?
Renal failure usually is caused by:
- effects of Cardiopulmonary bypass “CPB”, which is a technique by which the pumping action of the heart and the gas exchange action of the lung, are replaced temporarily by a mechanical device during the heart operation.
- secondary to chronic heart failure before heart transplantation.
- nephrotoxic agents, particularly Cyclosporin drug.
Why do some patients suffer from skin cancer after transplantation?
Malignancy may be developed due to chronic use of immunosuppression drugs and rarely from receiving transmitted malignant cells with the donor organ.
The malignancies are Lymphoproliferative of the Epstein-Barr virus type or B-Cell hyperplasias.
Cancers are an unfortunate consequence of chronic immunosuppression. In general, transplant recipients have a threefold increase in the incidence in various cancers when compared with age-matched controls. Some specific cancers are more than 100 times more frequent in immunosuppressed patients than in the general population.
For all tumours, the average time of appearance of the cancer after transplantation is 58 months. The most common tumours among transplant patients are those of the skin and lips, non-Hodgkin lymphomas, Kaposi sarcomas, and uterine, cervical, vulval, and perineal cancers.
What is rejection, and how many kinds are there?
Rejection of organ transplants is a complex immunologic phenomenon that involves cell-mediated and antibody-mediated responses, both of which are targeted on the human lymphocytes antigens in the graft.
The basis of morphology and the mechanisms involved in rejection have been classified as hyper acute, acute, and chronic.
- Hyper acute rejection:
- May occur within minutes or a few hours in pre-sensitised persons. It is characterised by widespread acute arteritis and arteriolitis, thrombosis of vessels, and ischemic necrosis, all of which result from reaction with pre formed humoral antibodies.
- As a consequence of the vascular damage, the graft never becomes vascularized and it undergoes ischemic necrosis.
- It should be noted that with the current practice of cross-matching (testing recipient for the presence of antibodies directed against donors lymphocytes), hyperacute rejection is no longer a significant clinical problem.
- Acute rejection:
- May occur within days of transplantation, or may appear suddenly months or even years later, after immunosuppression has been employed and terminated.
- Acute graft rejection is a combined process in which both cellular and humoral tissue injuries play parts. In any one patient, one or the other mechanism may predominate. Histologically, humoral rejection is associated with vasculitis, whereas cellular rejection is marked by an interstitial monocular cell infiltrate.
- Chronic rejection:
- In this type of rejection, the endothelial cells are damaged or destroyed, but the time constants of this part of heart rejection are generally much longer. Some researchers believe that the immunologic basis for accelerated coronary artery disease may be similar to rejection.
Why do some patients suffer from infection following transplantation?
Infection is an unfavourable outcome event, which almost always is related to the immunosuppression therapy.
About 30% of patients experience an infection episode, which most commonly develops within three months of transplantation.
The most common organ infected is the lung, and in one study, when this organ was involved the mortality was 22%.
The organism most frequently causing infection after heart transplantation is the Cytomegalovirus (CMV). Overall, viruses cause about 45% of infection, and bacteria about 45%; fungi and protozoa account for the remainder.
Why do coronary arteries get damaged after heart transplantation?
Accelerated coronary artery disease is the third most common cause of death after heart transplantation, following behind infection and acute rejection. The disease has a multifactorial aetiology, with little agreement about the relative importance of the various risk factors. Some studies provided evidence of immune involvement in this disease, and showed anti-endothelial antibodies in patients with accelerated coronary artery disease.
Why do most patients not feel pain, despite the existence of coronary disease after heart transplant?
Most of the patients with this disease after heart transplantation fail to experience typical angina (chest pain); this may be related to the likelihood that the heart allograft (donor heart) denervated permanently.
What are the common side effects of Cyclosporin drug?
All of the commonly used immunosuppressive drugs increase the risk of infection complications and cancer.
Cyclosporin toxicity may result in renal failure, liver failure, high blood pressure, and neurotoxicity.
Neurotoxic reaction are manifested by a fine tremor, paresthesias and, occasionally, seizures.
Other unusual side effects include the development of Hirsutism (abnormal hairiness), observed in almost all patients who receive Cyclosporin. This effect regresses as the dosage of Cyclosporin is lowered.
What are the techniques for heart transplantation?
There are two main techniques for heart transplantation:
Heterotopic, in which the donor heart is placed parallel to the recipient’s heart; and
Orthotopic, in which the patient’s heart is replaced with a donor heart.
- Heterotopic heart transplant
Exploration of the possibility of using the donor heart as an accessory pump had been carried out previously in laboratory experiments, most notably by Demikhov.
Two techniques were developed at the university of Cape Town, the first of which was a means of bypassing or supporting the left ventricle only, and the second a means of biventricular support.
Advantages and disadvantages of heterotopic as opposed to orthotopic heart transplantation:
- The recipient heart acts as a build in heart assist during;
- recovery from ischemia of donor heart sustained during transplantation;
- The recipient heart acts as a build in heart assist during;
sever acute rejection episodes.
- Recipient heart may maintain circulation after irreversible rejection while awaiting a second donor.
- Heterotopic transplant allows for some possible recovery of the recipient heart.
- Can be performed even in the presence of a high pulmonary vascular resistance.
- Risk of systemic emboli from clots in the poorly contracting recipient left ventricle.
- Continuing angina related to recipient ischemic heart muscle.
- Risk of infection and thrombus formation in relation to presence of the prosthetic valve in the recipient heart (this is a contraindication to heterotopic transplantation)
- Orthotopic heart transplantation
The technique of orthotopic heart transplantation has been well established for more than 30 years, based on the first description by Lower, Stofen, and Shamway. Nevertheless anastomosis of donor to recipient atria according to this technique creates atria cavities with abnormal geometry.
This abnormal geometry has been demonstrated to be responsible for tricuspid and mitral regurgitation and for arrhythmia’s resulting from sinus node injury. The risk of atrial septal aneurysms or atrial thrombus formation is certain. Because of these problems, some surgeons proposed a more anatomic surgical technique with complete excision of the recipient atria and direct anastomosis on the left pulmonary veins, right pulmonary veins, inferior vena cava and superior vena cava. But the benefit of this procedure on clinical outcome has not been demonstrated.