Heart transplants

Steff Chavez Human Physiology

What is a heart transplant?

An operation in which a diseased, failing heart is replaced with a healthier donor heart. (One must have heart failure)

It is a last resort—preformed when other treatments and operations have failed to improve a patient’s condition sufficiently.

A person’s chance of survival is good if appropriate follow-up care is received.

Heart failure

Heart failure (congestive heart failure) Heart cannot meet the body’s demand for blood—it

cannot pump enough blood to meet your body’s needs. Does not mean the heart is about to stop beating—

refers to the failure to pump sufficiently Caused by various conditions that, over time, result in a

heart that cannot pump or fill efficiently because it is too weak or stiff.

Can be treated with medications—can provide symptom relief and help extend life.

Lifestyle changes (exercise, reducing salt in diet, managing stress, treating depression, losing weight) can improve the quality of life of someone with heart failure.

To prevent heart failure it is important to control risk factors: coronary artery disease, high blood pressure, high cholesterol, diabetes, and obesity.

Types of heart failure

Left-sided heart failure Most common Fluid can backup into lungs

Right-sided hart failure Fluid can backup in abdomen, legs, and feet

(causes swelling) Can occur with left-sided heart failure

Systolic heart failure Left ventricle cannot contract properly Pumping problem

Diastolic heart failure Left ventricle cannot relax or fill properly Filling problem

Most common conditions that can lead to heart failure a transplant Coronary artery disease (most common) Cardiomyopathy Valvular heart disease Congenital heart defect Myocardial infarction (heart attack) High blood pressure Myocarditis (inflammation of heart muscle) Cardiac arrhythmias Pulmonary hypertension (high blood pressure in lungs’ vessels) Alcoholism or drug abuse Anemia (low red blood cell count) Previously failed heart transplant Other diseases: diabetes, hyperthyroidism, hypothyroidism, emphysema, lupus, hemochromatosis

(buildup of iron), amyloidosis (buildup of protein), and sarcoidosos (buildup of inflammatory cells) can contribute

Acute causes: viruses that attack the heart muscle, severe infections, blood clots, allergic reactions, certain medications

In children: Congenital heart defect Cardiomyopathy

Symptoms of heart failure

Shortness of breath (especially when exerting oneself and laying down)

Fatigue Weakness Swelling of ankles, feet, and legs Rapid/irregular heartbeat Decreased ability to exercise Coughing and wheezing (sometimes with bloody phlegm) Abdomen swelling Sudden weight gain (from retention of fluids) Lack of appetite Nausea Difficulty concentrating Reduced alertness

Complications of heart failure Kidney damage/failure

Blood flow to kidneys can be reduced Heart valve damage

Damage from blood and fluid buildup Liver damage

Fluid buildup can put too much pressure on the liver

Fluid buildup can lead to scarring on liver Heart attack and stroke

Increased risk

How to diagnose heart failure Blood tests Chest X-rays ECG (Electrocardiogram)

Records heart’s electrical activity Echocardiogram (most important)

Distinguish between types of heart failure Assess how well (or not well) the heart is pumping Measures the ejection fraction: percentage of blood pumped out of the

left ventricle Healthy ejection fraction: 50% (more than half the blood that fills the left

ventricle is pumped out of the chamber with each beat) Stress test Cardiac CT or MRI (computerized tomography or magnetic

resonance imaging) Angiogram (coronary catheterization)

Helps identify narrowed arteries Can help assess strength of left ventricle as well as health of heart valves

with a ventriculogram

Medications for heart failure Ace inhibitors (Angiotensin-converting enzyme)

Vasodilator (widens vessels) Helps lower blood pressure, improve blood flow, decrease heart’s work

Angiotensin II receptor blockers Digoxin (digitalis)

Increases strength of muscle contractions in heart Can slow heartbeat

Beta blockers Slow heart rate Lowers blood pressure Limit or reverse some heart damage

Diuretics Make you pee a lot Expelling fluid from body so fluid buildup is decreased (especially in lungs)

Aldosterone antagonists Diuretic Help reverse heart scarring which can lengthen lifespan

Surgeries for heart failure

Coronary bypass surgery Valve repair/replacement ICD (implantable cardioverter-defibrillator)

Like a pacemaker Monitors rhythm Helps shock heart back to normal rhythm Can speed heartbeat up if too slow

CRT (cardiac resynchronization therapy) Type of pacemaker that sends timed biventricular electrical impulses

LVAD (left ventricular assist device) Help weakened hart pump Used as an alternative to heart transplant for those who cannot have a

transplant Used for those waiting for heart transplant

Heart transplant

Back to heart transplants

Some history First human heart transplant preformed on December 3, 1967 Recipient: 53 year old Lewis Washkansky Donor: 25 year old Denise Darvall, fatally injured in a car crash Performed at Groote Schuur Hospital in Cape Town, South Africa Surgeon: Dr. Christiaan Barnard First successful heart transplant performed by Norman Shumway at Stanford

University on a dog in 1958 Lewis died 18 days later from pneumonia

New heart functioned normally Surgeons all over the world willing to try and within 2 years 150 heart transplants

were preformed But 80% of patients died within a year because vulnerable to infections By 1970, only 18 transplants Anti-rejection drugs were not as well developed as they are today

Better developed drugs came in 1970s In ‘70s, patients started living for up to 5 years

First successful heart transplant in US took place in 1968 First heat-lung transplant in 1981 2007: 2,210 heart transplants preformed in the United States

Risks of a heart transplant Rejection of heart

Immune system will attack the foreign object Patient given immunosuppressants to reduce risk of rejection 25% of recipients show signs and symptoms of rejection even up to a full year after their

transplant Typically rejection can be dealt with by adjusting medications Biopsies taken every few months to see if heart is being rejected

Artery problems Artery walls can thicken, harden Blood circulation can be difficult (can cause heart attack, heart failure, arrhythmias, or sudden

death) Side effects to medications Cancer (risk of immunosuppressants) Infection

Immunosuppressants inhibit body’s ability to fight infection Most transplant patients acquire an infection in the first year and have to be admitted

Bleeding Blood clots Breathing problems Kidney failure

Evaluation process

Psychological and social evaluations Stress Family support Financial issues

Blood tests Diagnostic tests

Evaluate overall health Assess health of lungs

Immunizations To minimize development of certain infections that

could end up affecting donor heart If good candidate for transplant, placed on

UNOS list

Restrictions

Not everybody is a viable candidate for a heart transplant Age 65+ Have some other medical condition that

shorten lifespan Peripheral artery disease (serious artery

blockages in arms or legs) Have had cancer Unwilling to maker certain lifestyle changes

such as not drinking, smoking, continuing drug abuse

Donor-recipient matching system Medical urgency Blood type Antibodies developed by recipient Size of donor heart Time spent on waiting list

Heart viability

Transplant needs to occur within four hours of heart’s removal from donor

Hearts first offered to transplant centers close by

Hearts come from people who have been declared brain dead Most common donors: gun shot and car crash

victims Must be declared brain dead by two physicians 1-2% of patients who die in hospitals are brain dead

Donors either already donors or family consents to donate organs

UNOS

United Network for Organ Sharing Manages national transplant waiting list Manages database of every organ

transplant in US since 1986 Develop policies to best use the limited

supply of organs

OPTN

Organ Procurement and Transplantation Network

National Organ Transplant Act passed in 1987 by Congress established OPTN and Scientific Registry of Transplant Recipients Act stipulated that network be private

sector, nonprofit OPTN is administered by UNOS

The wait

Can be days, months, years Average wait: 3-5 years (all organs) There are not enough hearts for every

person who needs one People die while waiting Can be removed temporarily if serious

medical condition develops (infection, stroke)

VADs can be used

Position on list (and waiting times) can be affected by… Blood type Tissue type Height and weight of recipient Size of donated organ Medical urgency Time on waiting list Distance between the recipient, the

donor organ, and the transplant center

The list

Today as of 6:08 AM: Waiting list candidates: 117,257 (all organs) Active candidates: 74,608 Transplants from January-November 2012: 25,787 Donors from January-November 2012: 12,874 3,461 waiting for a heart transplant

2011 for hearts 67.8 transplants per 100 wait-list years http://srtr.transplant.hrsa.gov/annual_reports/2011/p

df/05_heart_12.pdf

2008: 60% of those waiting for heart transplant underwent the transplant within the first 12 months of listing By 12 months 25% were still waiting, 9.5% had died

The procedure Usually lasts about 4 hours IV line will be started to administer fluids and medications during surgery Catheter inserted Anesthesia administered Incision made from center of chest to abdomen (just above the bellybutton) Sternum cut in half with a surgical saw Two halves of sternum separated to expose heart Pericardium opened Recipient aorta and pulmonary arteries are not replaced as part of transplant Tubes will be inserted into chest so that blood can be pumped through body by a

heart-lung machine Once blood is diverted completely into heart lung machine diseased heart will be

removed EXCEPT a recipient ventricle will be left in place (usually the left ventricle) Donor heart is sewn in to place and vessels connected Heart lung machine turned off, blood allowed back into heart Heart shocked to restart heartbeat Heart will be observed to make sure it is working properly and that no reconnected

vessels are leaking

Procedure continued

Sternum wired back together Skin sewn back together Initial incision closed with sutures or surgical

staples Tubes inserted into chest to train any blood

or excess fluids from around the heart Dressing/bandage applied Will be in hospital for 7-21 days after

procedure http://www.pbs.org/wgbh/nova/eheart/

transplantwave.html

Some fun pictures…

Heterotopic heart transplant “Piggyback transplant” Attach donor heart to recipients heart Hearts work together Donor heart takes stress off of

recipient’s heart Used when recipient’s heart is too weak

to function on its own

Some statistics (United States) Roughly 79 transplants take place

everyday (all organs) More than 28,000 transplants every year

(all organs) One donor can help 50 people (with all of

his/her organs/parts) Roughly 18 people die everyday waiting

for a transplant (all organs)

Survival rate in US

90% after one year 74% after five years

Ethical Issues

Organ shortage Note enough organs for everyone in need Organ shortage most problematic for hearts

because a heart cannot come from a live donor

The list Does the list determining who gets the next

viable heart do so ethically? What is the most important factor? Should age play a role?

Black market (for other organs)

How do we get more donors? Persuade more people to become organ

donors when they die Go to organdonor.gov to become a donor!

Implement hospital policies and procedures to foster organ donation

Obtain more organs from victims of brain and cardiac death

Increase number of live donors Only 1 in 4 people have indicated that they

are donors on appropriate forms in this country

Age is not a limit for donation!

The future of hearts

Embryonic stem cells Get stem cells to become heart cells Replace damaged heart tissue Controversy

“primordial progenitor cells” Study at Mass Gen Cells multiply and diversify into multipotent cardiovascular cell

lineages for several weeks These cells give rise to production of other cells These cells present from weeks 11-18 of gestation These cells are gradually lost ISL1—differentiation potential being assessed Regeneration, transplants (especially for myocardium) Trying to help understand how in development some cells lead

to congenital heart defects

Future continued

Stimulate heart’s ability to grow new cells Cell division believed to be bad for heart b/c can lead to many DNA

replication errors and lead to disruption of electrical system Growing new organs

Using body itself to nourish encourage engineered tissue to grow Growing entire organs is far away but growing structures may not be Study using intestinal tissue where intestinal tissue was grown. New

tissue replaced diseased tissue. Bladders and windpipes have been grown

Windpipe: exact copy made from porous, fibrous plastic that was then seeded in stem cells that were taken from bone marrow. It was then placed in a type of incubator, then sewn in to the recipient

Study where rat hearts and lungs were stripped of living cells, leaving the structure of the organ Scaffolds: “compounds that act like mortar to hold cells in their proper

place that also play a major role in how cells are recruited for tissue repair”

Very expensive

Future continued

Study in zebrafish They regrow their cardiac tissue In 1 week, can repair 20% of its cardiac tissue Hopefully, one day, human heart can mend itself Key protein: thymosine beta-4 which triggers

growth of epicardium membrane Drugs to help heart mend itself being researched using

this protein Goal: those with diseases can make full recovery Goal: make heart transplant surgery unnecessary

because heart can repair damage itself

Sources

www.nhlbi.nih.gov www.Nyp.org www.mayoclinic.com www.cts.usc.edu www.heart.org www.unos.org www.pbs.org www.clevelandclinic.org www.hopkinsmedicine.org www.nytimes.com www.ohsu.edu www.history.com www.time.com www.optn.transplant.hrsa.gov/