Heart transplantation

A heart transplant, or a cardiac transplantation, is a surgical transplant procedure performed on patients with end-stage heart failure or severecoronary artery disease. As of 2008 the most common procedure was to take a working heart from a recently deceased organ donor (cadavericallograft) and implant it into the patient. The patient's own heart is either removed (orthotopic procedure) or, less commonly, left in place to support the donor heart (heterotopic procedure); both were controversial solutions to an enduring human ailment. Post-operation survival periods averaged 15 years.

^{Contraindications}

Some patients are less suitable for a heart transplant, especially if they suffer from other circulatory conditions unrelated to the heart. The following conditions in a patient increase the chances of complications:

• Kidney, lung, or liver disease
• Insulin-dependent diabetes with other organ dysfunction
• Life-threatening diseases unrelated to heart failure
• Vascular disease of the neck and leg arteries.
• High pulmonary vascular resistance
• Recent thromboembolism
• Age over 60 years (some variation between centers)
• Substance abuse (which increases the chance of lung disease)

Pre-operative

A typical heart transplantation begins when a suitable donor heart is identified. The heart comes from a recently deceased or brain dead donor, also called a beating heart cadaver. The patient is contacted by a nurse coordinator and instructed to come to the hospital for evaluation and pre-surgical medication. At the same time, the heart is removed from the donor and inspected by a team of surgeons to see if it is in suitable condition. Learning that a potential organ is unsuitable can induce distress in an already fragile patient, who usually requires emotional support before returning home.

The patient must also undergo emotional, psychological, and physical tests to verify mental health and ability to make good use of a new heart. The patient is also given immunosuppressant medication so that the patient's immune system does not reject the new heart.

Transplanted heart

Operative

Once the donor heart passes inspection, the patient is taken into the operating room and given a general anaesthetic. Either anorthotopic or a heterotopic procedure follows, depending on the conditions of the patient and the donor heart

Orthotopic procedure

The orthotopic procedure begins with a median sternotomy, opening the chest and exposing the mediastinum. The pericardium is opened, the great vessels are dissected and the patient is attached to cardiopulmonary bypass. The donor's heart is injected with potassium chloride. KCl stops the heartbeat before the heart is removed from the donor's body and packed in ice. Ice can usually keep the heart usable four to six hours depending on preservation and starting condition. The failing heart is removed by transecting the great vessels and a portion of the left atrium. The patient's pulmonary veins are not transected; rather a circular portion of the left atrium containing the pulmonary veins is left in place. The donor heart is trimmed to fit onto the patient's remaining left atrium and the great vessels are sutured in place. The new heart is restarted, the patient is weaned from cardiopulmonary bypass and the chest cavity is closed.

Heterotopic procedure

In the heterotopic procedure, the patient's own heart is not removed. The new heart is positioned so that the chambers and blood vessels of both hearts can be connected to form what is effectively a 'double heart'. The procedure can give the patient's original heart a chance to recover, and if the donor's heart fails (e.g., through rejection), it can later be removed, leaving the patient's original heart. Heterotopic procedures are used only in cases where the donor heart is not strong enough to function by itself (because either the patient's body is considerably larger than the donor's, the donor's heart is itself weak, or the patient suffers from pulmonary hypertension).

Living organ' transplant

In February 2006, at the Bad Oeynhausen Clinic for Thorax and Cardiovascular Surgery, Germany, surgeons successfully transplanted a 'beating heart' into a patient. Rather than cooling the heart, the living organ procedure keeps it at body temperature and connects it to a special machine called an Organ Care System that allows it to continue pumping warm, oxygenated blood. This technique can maintain the heart in a suitable condition for much longer than the traditional method.

The patient is taken to the ICU to recover. When they wake up, they move to a special recovery unit for rehabilitation. The duration of in-hospital, post-transplant care depends on the patient's general health, how well the heart is working, and the patient's ability to look after the new heart. Doctors typically prefer that patients leave the hospital 1 – 2 weeks after surgery, because of the risk of infection and presuming no complications. After release, the patient returns for regular check-ups and rehabilitation. They may also require emotional support. The frequency of hospital visits decreases as the patient adjusts to the transplant. The patient remains on immunosuppressant medication to avoid the possibility of rejection. Since the vagus nerve is severed during the operation, the new heart beats at around 100 beats per minute unless nerve regrowth occurs.

The patient is regularly monitored to detect rejection. This surveillance can be performed via frequent biopsy or a gene expression blood test known as AlloMap Molecular Expression Testing. Typically, biopsy is performed immediately post-transplant and then AlloMap replaces it once the patient is stable. The transition from biopsy to AlloMap can occur as soon as 55 days after the transplant.

Complications

Post-operative complications include infection, sepsis, organ rejection, as well as the side-effects of the immunosuppressive medication. Since the transplanted heart originates from another organism, the recipient's immune system typically attempts to reject it. Immunosuppressive drugs reduce that risk, but may cause unwanted side effects, such as increased likelihood of infections or nephrotoxic effects. Many recent advances in reducing complications due to tissue rejection stem from mouse heart transplant procedures.

Prognosis

The prognosis for heart transplant patients following the orthotopic procedure has increased over the past 20 years, and as of June 5, 2009, the survival rates were:

• 1 year : 88.0% (males), 86.2% (females)
• 3 years: 79.3% (males), 77.2% (females)
• 5 years: 73.1% (males), 69.0% (females)

World first human heart transplantaion in 1967

In a November 2008 study conducted on behalf of the U.S. federal government by Dr. Eric Weiss of the Johns Hopkins University School of Medicine, it was discovered that heart transplants — other factors equal — work better in male to male and female to female transplants. However, due to the scarcity of donors, this is not always feasible.

Reference

1. ^ a b Till Lehmann (director) (2007). The Heart-Makers: The Future of Transplant Medicine (documentary film). Germany: LOOKS film and television.
2. ^ "Memories of the Heart". Doylestown, Pennsylvania: Daily Intelligencer. November 29, 1987. p. A–18.
3. ^ Reiner Körfer (interviewee) (2007). The Heart-Makers: The Future of Transplant Medicine (documentary film). Germany: LOOKS film and television.
4. ^ "Cedars-Sinai Heart Institute Ranked First Nationally in 2010 Adult Heart Transplants". March 9, 2011. Retrieved November 18, 2011.
5. ^ Custodiol Htk Solution patient advice including side effects
6. ^ "Bad Oeynhausen Clinic for Thorax- and Cardiovascular Surgery Announces First Successful Beating Human Heart Transplant". TransMedics. 23 February 2006. Retrieved 2007-05-14.
7. ^ Bishay, R. The ‘ Mighty Mouse’ Model in Experimental Cardiac Transplantation. Hypothesis 2011, 9(1): e5.
8. ^ Heart Transplants: Statistics The American Heart Association. Retrieved 25 June 2011.
9. ^ http://www.columbusdispatch.com/live/content/local_news/stories/2009/08/10/aheart.html?sid=101
10. ^ Heart Transplant Patient OK After 28 Yrs (14 September 2006) CBS News. Retrieved 29 December 2006.
11. ^ Dwight Kroening first heart transplant to do ironman Retrieved 27 August 2008.
12. ^ Glick, Shav (31 January 1996). "Kidney Transplant a Success for Shelby". Los Angeles Times.
13. ^ "New heart, new hope: Golfer Compton achieves PGA Tour dream". CNN. 24 January 2012.
14. ^ "Cheney undergoes heart transplant surgery". Fox News. 24 March 2012.

Tetralogy of Fallot ( TOF )

Tetralogy of Fallot (TOF) is a congenital heart defect which is classically understood to involve four anatomical abnormalities (although only three of them are always present). It is the most common cyanotic heart defect, and the most common cause of blue baby syndrome.

Tetralogy of Fallot causes low oxygen levels in the blood. This leads to cyanosis (a bluish-purple color to the skin).

The classic form includes four defects of the heart and its major blood vessels:

• Ventricular septal defect VSD
• Pulmonary Infundibular Stenosis
• Overriding aorta
• Right ventricular hypertrophy
  
  

Tetralogy of Fallot is rare, but it is the most common form of cyanotic congenital heart disease. Patients with tetraology of Fallot are more likely to also have other congenital defects.

The cause of most congenital heart defects is unknown. Many factors seem to be involved.

Factors that increase the risk for this condition during pregnancy include:

• Alcoholism in the mother
• Diabetes
• Mother who is over 40 years old
• Poor nutrition during pregnancy
• Rubella or other viral illnesses during pregnancy
  
  

Children with tetralogy of Fallot are more likely to have chromosome disorders, such as Down syndrome and DiGeorge syndrome (a condition that causes heart defects, low calcium levels, and poor immune function).

Symptoms 

• Blue color to the skin (cyanosis), which gets worse when the baby is upset
• Clubbing of fingers (skin or bone enlargement around the fingernails)    
• Difficulty feeding (poor feeding habits)
• Failure to gain weight
• Passing out
• Poor development
• Squatting during episodes of cyanosis

Chest X-Ray of  child with Teratology of fallot 

Diagnosis

A physical examination with a stethoscope almost always reveals a heart murmur.

Tests may include:

Before more sophisticated techniques became available, chest x-ray was the definitive method of diagnosis. Congenital heart defects are now diagnosed with echocardiography, which is quick, involves no radiation, is very specific, and can be done prenatally.

The abnormal "coeur-en-sabot" (boot-like) appearance of a heart with tetralogy of Fallot is classically visible via chest x-ray, although most infants with tetralogy may not show this finding.Absence of interstitial lung markings are another classic finding in tetralogy.

Additional anomalies

In addition, tetralogy of Fallot may present with other anatomical anomalies, including:

1. stenosis of the left pulmonary artery, in 40% of patients
2. a bicuspid pulmonary valve, in 40% of patients
3. right-sided aortic arch, in 25% of patients
4. coronary artery anomalies, in 10% of patients
5. a foramen ovale or atrial septal defect, in which case the syndrome is sometimes called a pentalogy of Fallot
6. an atrioventricular septal defect
7. partially or totally anomalous pulmonary venous return
8. forked ribs and scoliosis

Treatment

Surgery to repair tetralogy of Fallot is done when the infant is very young. Sometimes more than one surgery is needed. When more than one surgery is used, the first surgery is done to help increase blood flow to the lungs.

Surgery to correct the problem may be done at a later time. Often only one corrective surgery is performed in the first few months of life. Corrective surgery is done to widen part of the narrowed pulmonary tract and close the ventricular septal defect.

Prognosis:

Most cases can be corrected with surgery. Babies who have surgery usually do well. More than 90% survive to adulthood and live active, healthy, and productive lives. Without surgery, death usually occurs by the time the person reaches age 20.

Patients who have continued, severe leakiness of the pulmonary valve may need to have the valve replaced.

Regular follow-up with a cardiologist to monitor for life-threatening arrhythmias is recommended.

Complications

• Delayed growth and development
• Irregular heart rhythms (arrhythmias)
• Seizures during periods when there is not enough oxygen
• Death

Treatment

Emergency

Prior to corrective surgery, children with tetralogy of Fallot may be prone to consequential acute hypoxia (tet spells), characterized by sudden cyanosis and syncope. These may be treated with beta-blockers such as propranolol, but acute episodes may require rapid intervention with morphine to reduce ventilatory drive and a vasopressor such as epinephrine, phenylephrine, or norepinephrine to increase blood pressure. Oxygen (100%) is effective in treating spells because it is a potent pulmonary vasodilator and systemic vasoconstrictor. This allows more blood flow to the lungs. There are also simple procedures such as squatting and the knee chest position which increases aortic wave reflection, increasing pressure on the left side of the heart, decreasing the right to left shunt thus decreasing the amount of deoxygenated blood entering the systemic circulation.

Palliative surgery

palliative surgical procedure, which involved forming an anastomosis between the subclavian artery and the pulmonary artery. This redirected a large portion of the partially oxygenated blood leaving the heart for the body into the lungs, increasing flow through the pulmonary circuit, and greatly relieving symptoms in patients. 

The Potts shunt and the Waterston-Cooley shunt are no longer used.

Currently, Blalock-Thomas-Taussig shunts are not normally performed on infants with TOF except for severe variants such as TOF with pulmonary atresia (pseudotruncus arteriosus).

Total surgical repair

Total repair of Tetralogy of Fallot initially carried a high mortality risk. This risk has gone down steadily over the years. Surgery is now often carried out in infants one year of age or younger with less than 5% perioperative mortality. The open-heart surgery is designed (1) to relieve the right ventricular outflow tract stenosis by careful resection of muscle and (2) to repair the VSD with aGore-Tex patch or a homograft. Additional reparative or reconstructive surgery may be done on patients as required by their particular cardiac anatomy.

References

1. Webb GD, Smallhorn JF, Therrien J, Redington AN. Congenital heart disease. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011: chap 65.
2. Cheng TO (1995). "Pentalogy of Cantrell vs pentalogy of Fallot". Tex Heart Inst J 22 (1): 111–2. PMC 325224. PMID 7787464.
3. Boshoff D, Budts W, Daenen W, Gewillig M (January 2005). "Transcatheter closure of a Potts' shunt with subsequent surgical repair of tetralogy of fallot". Catheter Cardiovasc Interv 64 (1): 121–3. DOI:10.1002/ccd.20247. PMID 15619282.

Ventricular septal defect VSD

is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart.

The ventricular septum consists of an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes.

The membranous portion, which is close to the atrioventricular node, is most commonly affected in adults and older children in the United States. It is also the type that will most commonly require surgical intervention, comprising over 80% of cases.

Membranous ventricular septal defects are more common than muscular ventricular septal defects, and are the most common congenital cardiac anomaly.

Diagnosis

A VSD can be detected by cardiac auscultation. Classically, a VSD causes a pathognomonic holo- or pansystolic murmur. Auscultation is generally considered sufficient for detecting a significant VSD. The murmur depends on the abnormal flow of blood from the left ventricle, through the VSD, to the right ventricle. If there is not much difference in pressure between the left and right ventricles, then the flow of blood through the VSD will not be very great and the VSD may be silent. This situation occurs a) in the fetus (when the right and left ventricular pressures are essentially equal), b) for a short time after birth (before the right ventricular pressure has decreased), and c) as a late complication of unrepaired VSD. Confirmation of cardiac auscultation can be obtained by non-invasive echocardiography. To more accurately measure ventricular pressures, cardiac catheterization, can be performed.

Signs and symptoms

Ventricular septal defect is usually symptomless at birth. It usually manifests a few weeks after birth.

Symptoms

VSD is an acyanotic congenital heart defect, aka a Left-to-right shunt, so there are no signs of cyanosis.

Signs

Pansystolic (Holosystolic) murmur (depending upon the size of the defect) +/- palpable thrill (palpable turbulence of blood flow). Heart sounds are normal. Larger VSDs may cause a parasternal heave, a displaced apex beat (the palpable heartbeat moves laterally over time, as the heart enlarges). An infant with a large VSD will fail to thrive and become sweaty and tachypnoeic (breathe faster) with feeds.

CAUSES: The cause of VSD ( ventricular septal defect) includes the incomplete looping of the heart during days 24-28 of development. Faults with NKX2.5 gene can cause this.

Complications

• Aortic insufficiency (leaking of the valve that separates the left ventricle from the aorta)
• Damage to the electrical conduction system of the heart during surgery (causing an irregular heart rhythm)
• (failure to thrive in infancy)
• Heart failure
• Infective endocarditis
• Pulmonary hypertension
  
  

Treatment 

Most cases do not need treatment and heal at the first years of life. Treatment is either conservative or surgical. Smaller congenital VSDs often close on their own, as the heart grows, and in such cases may be treated conservatively. Some cases may necessitate surgical intervention, i.e. with the following indications:

1. Failure of congestive cardiac failure to respond to medications

2. VSD with pulmonic stenosis

3. Large VSD with pulmonary hypertension

4. VSD with aortic regurgitation

For the surgical procedure, a heart-lung machine is required and a median sternotomy is performed. Percutaneous endovascular procedures are less invasive and can be done on a beating heart, but are only suitable for certain patients. Repair of most VSDs is complicated by the fact that the conducting system of the heart is in the immediate vicinity.

Ventricular septum defect in infants is initially treated medically with cardiac glycosides (e.g., digoxin 10-20mcg/kg per day), loop diuretics (e.g., furosemide 1–3 mg/kg per day) and ACE inhibitors (e.g., captopril 0.5–2 mg/kg per day).

References  

1. Cameron P. et al: Textbook of Paediatric Emergency Medicine. p116-117 [Elsevier, 2006]