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/