Heart transplant

250px|náhled|vpravo|Christiaan Neethling Barnard - první člověk, který provedl transplantaci srdce

Heart transplant is an established clinical method for the treatment of terminal stages of heart failure. Transplantation itself is a surgical method, however it is part of the entire treatment program of a multidisciplinary team. It is indicated only in a certain group of patients, which requires the availability of a donor graft, and has complications associated with the procedure.

In the Czech Republic, approximately 5 heart transplants / 1,000,000 people are performed annually. Legally, a potential donor is anyone who is allowed to be entered in the register for donors until death. However, if not registered, it is a common practice to follow the wishes of the deceased's family.They may choose whether to donate the dead relative's organs. On the waiting list for heart transplants in Czech republic,52 % of patients are diagnosed with dilated cardiomyopathy and  40 % of patients are diagnosed with advanced  ischemic heart disease.Heart transplantation in the Czech Republic is performed by two centers, IKEM in Prague and CKTCH in Brno.

The history of heart transplants dates back to the 60s of the 20th century. Norman Shumway in particular took part in the development of the surgical technique of heart transplantation and the first heart transplant in humans was performed by Christiaan Barnard.

Types of transplantation
250px|vpravo|náhled|Transplantované srdce v hrudníku příjemce

It is possible to divide transplants according to location and origin of the graft:


 * heterotopic allotransplantation – No longer used today;
 * orthotopic allotransplantace – Most commonly used today;
 * transplantation of heart and lung
 * xenotransplantation – not used, previously there were experiments with chimpanzee hearts;
 * cellular transplantation – Theoretical transplantation of cells that restore cardiomyocytes.

Indication
Heart transplantation is performed in patients with heart failure ,who are unable to tolerate physical exercise,require circulatory support, Develop organ disorders (increase in serum creatinine, increase in bilirubin, increase in PAR), hyponatremia, hypochloremia and begin to undergo cachexia. Indication criteria include:


 * NYHA III−IV unresponsive to treatment, supplemented with spiroergometry;(VO2 max to 12 ml/kg/min);
 * life prognosis is less than 1 year;
 * there is no other treatment alternative than transplantation;
 * age less than 60 years ;
 * there is a history of good adherence to previous treatment and a good psychosocial environment (ie it cannot be performed in alcohol dependent patients, etc.).

Bridging heart transplantation
Methods that allow the patient to prolong the life expectancy of the patient while waiting for a transplant. This includes:


 * revascularization;
 * anti-remodeling interventions – endoventricular patch (synthetic or biological) are mainly used for ventricular aneurysms as a complication of a heart attack, elimination of scar tissue from the circulation from the bloodstream will increase the ejection fraction;
 * resynchronization – this is mainly biventricular pacing, which allows a more physiological transfer of the action potential than monoventricular pacing and thus increase the ejection fraction;
 * mechanical circulatory support.

Preoperative examination
The recipient must have a compatible blood group in the AB0 system comparable height and weight(± 15 %) and a transplantable status as determined by the tests performed below. Recipient to be transplanted with a compatible heart graft also depends on their position in the waiting list.

Basic examination
The patient must undergo a routine preoperative examination, which includes medical history, physical examination, ECG, heart + lung X-ray, ECHO, and basic biochemistry.

Spiroergometry
350px|vpravo|náhled|Spiroergometrie Spirometry, and in particular spiroergometry, is performed to indicate the patient's prognosis if no transplant is performed. (Prognosis shorter than 1 year is one of the indication criteria.) VO2 max ≤ 10 ml/kg/min. indicates a poor prognosis, but even provides information on the evolution of this parameter over time.

Catheterization of pulmonary artery
A left heart failure causes congestion in the pulmonary circulation and thus secondary pulmonary hypertension. If pulmonary hypertension is irreversible and the patient is transplanted with a healthy heart that is not adapted to this burden, it would dilate. It is therefore necessary to rule out irreversible pulmonary hypertension in advance, and therefore pulmonary catheterization is performed. Exact transpulmonary gradient (TPG) and PAR values ​​vary by workplace, however TPG ≥ 15 or PAR ≥ 3 corresponds to an increased risk of pulmonary hypertension and TPG> 20 or PAR> 4 is a contraindication to transplantation. Prostaglandin E1 (alprostan) is used to differentiate between reversible and irreversible pulmonary hypertension.

Donor graft
The deceased's donor graft is ideally taken from a man under 55 years of age or a woman under 60 years of age with a known history, ECG, echocardiography, catecholamine and CK-MB levels (<0.5 mmol / l). Legislatively, a donor can be anyone who is not in the register of non-donor organs, however, according to the customs of workplaces, the consent of the deceased's family is required in the Czech Republic.

Surgical technique
Today, the bicaval technique is mainly performed. At present, orthotropic transplantation is performed exclusively, where the patient's heart is removed from the chest and replaced by the donor's heart. The whole operation must be performed very quickly, because the donor's heart must not be left out of the body for more than 4-5 hours. The patient is under general anesthesia and is connected to the extracorporeal circulation, which provides a temporary replacement of the heart's pumping function and gas exchange in the lungs. The diseased heart is disconnected from the two main vessels. The new heart is then placed in and the main vessels are sutured to it. Although it may seem relatively simple, the operation is very demanding.

After the operation, the patient is placed in an intensive care unit (ICU), where he remains connected to a respirator (ventilator). If the postoperative condition proceeds without complications, the ventilator is gradually disconnected.The patient remains under intensive supervision until the date of the first heart tissue biopsy. He is then transferred to a normal ward, where he spends 3-4 weeks before being released home. During this time, possible signs of heart rejection are monitored, blood samples are taken regularly, frequent echocardiographic examinations are performed, and the patient learns to take medication properly and follow a certain regimen.

Immunosuppressive drugs
A triple combination is used as standard. Possible immunosuppressants are:


 * cyclosporin A;
 * tacrolimus;
 * azathioprine;
 * rapamycin;
 * mycophenolate mofetil (IMF);
 * prednisone.

Status after transplantation
Transplantované srdce je denervované. Z toho plyne klidová tachykardie, špatná snášenlivost zátěže (vzhledem k zdravému srdci, ne vzhledem k selhávajícímu srdci), zvýšené riziko náhlé srdeční zástavy (opět vzhledem ke zdravému srdci), chybí bolest při ischemii (riziko němého infarktu myokardu).

Complications
Kromě časných obecných komplikací v kardiochirurgii jsou možné komplikace:


 * rejekce štěpu, zejména
 * koronární nemoc štěpu
 * infekce
 * toxicita a nežádoucí účinky imunosupresivní terapie
 * malignity

Graft rejection
Rejekce štěpu může být perakutní, časná a pozdní. Perakutní a pozdní je vždy humorální, časná může být jak humorální, tak buněčná. Monitorace rejekce štěpu se provádí pravidelnou endomyokardiální biopsií.

coronary graft disease
K monitorování koronární nemoci štěpu se používá endovaskulární sonografie věnčitých tepen. Jedná se o takřka nevyhnutelnou komplikaci, nicméně její výskyt lze částečně snížit či alespoň oddálit několika způsoby:


 * výběr srdečního štěpu s vhodnými vlastnostmi (při nedostatku štěpů víceméně pouze teoreticky);
 * včasná léčba buněčné rejekce štěpu (velmi důležité);
 * prevence CMV infekce (léčba ganciclovirem atd.).

Související stránky

 * Srdeční selhání
 * Dilatační kardiomyopatie
 * Ischemická choroba srdeční
 * Pravostranná srdeční katetrizace

Externí odkazy

 * IKEM Praha
 * CKTCH Brno
 * | Transplantace srdce (anglická wikipedie)
 * | Christiaan Barnard