Lecture 8: The Heart
-Ancient Egyptians thought heart was center of emotions and intellect- when made mummies,
they kept heart in jar and put it back in body cause thought would be useful in afterlife;
-Ancient Romans thought the heart made blood and pumped it through the arteries to deliver
“vital spirit” (saw heart still pounding after killing someone-gladiators).
-Leonardo Davinci(1452-1519)- first scientist to look at heart scientifically and drew very
accurate pictures of it.- A surgeon in UK has pioneered a new way to repair damaged hearts
after being inspired by artist Leonardo da Vinci’s medical drawings.
-William Harvey (1578-1657)- British scientist who first really understood what the heart did. It
is a pump for blood around the body. The heart has two functions: to pump blood to lungs for
oxygenation via veins and pulmonary artery, and brought back from lungs to body through aorta.
-It pumps 5-6L per minute through 100,000km. of blood vessels beating up to 2.6 billion times
through a lifetime. Red= oxygenated blood; blue=venous blood (largest vein is vena cava);
every single cell in the body needs oxygen and nutrients and blood is the medium where these
two substances are found. Blood vessels reduce in size as go further from heart until they
become capillaries (1 red blood cell at a time) then larger-arterioles, arteries; The circulatory
system is closed.
-Things that can go wrong with the heart:
1. Failure to pump enough blood
2. impairment of electrical activity (pacemaker)
3. reduced flow of blood through coronary arteries (sit on top of heart like a crown)
4. improper functioning of heart valves (one way to go to different chambers of heart)
Risk factors for Heart Disease
1. Family History
2. Crease in earlobe (a marker)- same genes that control the functioning of the heart
control the formation of this ear lobe. Watch other risk factors
3. Men that go bald early have higher risk to get heart disease (probably hormonal-
dihormonal (?) testosterone)
4. Male gender (far greater rates than women until the age of menopause where it evens
out)- The number 1 killer of women (1 of 3 women will die of heart disease). Women
symptoms differ from men too- panic, diffuse symptoms, etc. Why? Estrogen? Give
estrogen supplements after menopause didn’t make a difference during randomized
control trials. Actually found that supplements increase risk of breast cancer. 5. Smoking- link between heart disease and smoking is greater than the link between
cancer and smoking
7. Diabetes (related to 6.)-if glucose is high and not used, becomes fat and oxalated=heart
disease since accumulates in arteries; How do you know if you have high blood
glucose?- measure it (mg/dL[US]=mmol/L*18[Canada-SI]- ex. 126=7*18) since there are
no symptoms. After an overnight fast, above 7 mmol/L is diabetes, between 5.5-7
mmol/L is prediabetes. Drink a liquid with specific amount of glucose in it and measure
an hour ish later, above 11mmol/L is diabetes and between 7.8-11mmol/L is prediabetes.
Diabetes is not associated with symptoms. Excessive thirst/urination and vision blurred
can be symptoms, but often asymptomatic. Sometimes symptoms will hit you all of a
sudden. To follow someone being treated for diabetes, follow by measuring Hemoglobin
A1c (red blood cells last about 3 months; when too much glucose in blood, glucose will
bind to surface of red blood cells)- average blood sugar over 2-3 months. Less than 7%
(corresponds to average blood glucose of 8.3 mmol/L) means relatively well controlled.
Can also monitor fasting or premeal glucose in machine:
Ideal Optimal Suboptimal Inadequate
Fasting or 4.0-6.0 4.0-7.0 7.1-10.0 >10.0
1-2 hrs 5.0-8.0 5.0-10.0 10.1-14.0 >14.0
Remember number 7. Up to 50% of prediabetics will develop diabetes in 5-10 yrs. Must cut
back from empty carbs to control prediabetes.
8. Cholesterol- builds up in body because of diet. Cholesterol is needed to make many
hormones, but in high levels will cause deposits in arteries. Around a third of all heart
attacks and strokes can be avoided in people at high risk by using statin drugs to lower
cholesterol. Use drugs if other risks factors for heart disease present too (need to see
overall picture). Statins (ex. Zocor and Lipitor) cause side effect- muscle aches that can
be very severe, must monitor liver functions. Must weigh risks vs benefits.
9. Homocysteine- forms in the body naturally and is also broken down naturally in the
presence of B vitamins. Without adequate B vitamins, homocysteine reaches levels that
are toxic to the cells that line blood vessels= heart attacks. Test by giving people B
vitamins, which reduced homocysteine, but didn’t reduce risk of heart disease ex.
10. Inflammation- Tissues get red and swollen, rise in temperature and becomes painful.
Happens in coronary arteries, can cause heart attack. Know you have inflammation by
measuring c-reactive protein (measure by a blood test- 1997-Harvard study: Healthy
men with the highest level of c-reactive protein had three times the heart attack risk- doesn’t mean this causes heart attack but association so should run more tests if this is
high). While an elevated CRP value is not specific for any condition, it is a very sensitive
index of ongoing inflammation. In differentiating between bacterial and viral infections,
the CRP level is of some use. A very high CRO (>100mg/L) is more likely to occur in
bacterial than viral infection, and a normal CRP is unlikely in the presence of bacterial
infection. However, intermediate CRP levels (10-50mg/L) may be seen in both bacterial
and viral conditions.- not cheap to do therefore not routine to do but is getting there.
11. Bacteria- (Chlamydia pneumonia)- early study showed that giving people low doses of
antibiotics lowered chance of heart disease. A year after receiving a week-long course
of antibiotics, heart disease patients were 40% less likely to suffer another heart attack
or hospitalization for chest pain. But better tests started in early 2000s and found that
bacteria do not cause heart disease. Though bacterial infections does weaken the body.
12. Hypertension (high blood pressure)- not necessarily caused by stress. It is when you
have continuous high pressure. Systolic/diastolic (d for denominator); Top number
represents pressure of blood when heart is actively pumping therefore always higher
(120/80 mm of mercury ideal; high over 130/90) and bottom number when relax.
White coat hypertension-higher BP cause nervous at doctor’s office therefore need to
see many times before diagnosing as high BP. Can buy home monitor to make sure.
High blood pressure predisposes us to heart disease. Study-better to be in a
good/loving relationship for heart. There is a link between emotional situations and
How can high blood pressure be reduced?
-Exercise (significant effect): general advice is equivalent of 30 minutes per day or
7*30min in a week (can be walking, biking, etc. doesn’ t need to be treadmill or jogging)
-Dietary Approach to Stop Hypertension (DASH diet)- a diet high in whole grains, fruits
(especially bananas since high in potassium), begetables and low-fat dairy and restricted
in fat (red meat included).
-Control salt intake: Sodium causes body to retain more water= more liquid in blood
therefore more pressure. This means reducing processed food. Table salt has little
effect on total sodium. LABEL READING.
*If diet and exercise don’t work, THEN use medications. There are a number of
medications to take.
-Diuretics (1 step since have best profile to reduce blood pressure= pee more therefore
less water in body. Used to have problem losing too much potassium in pee but now
have potassium sparing diuretics ex. Dyazide) Diuretics make it difficult for the kidneys
to retain water and salt, which are then filtered out into the urine. Increasing the amount of urine reduces the amount of fluid in the bloodstream, and hence the pressure on
artery walls. It also has very little side effects.
*If this doesn’t work, next prescription depends on where went to med school.
- ace inhibitors- Blocks formation of angiotensin II which increases blood pressure.
Angiotensin’s normal role is to maintain equilibrium when blood pressure drops. It acts
directly on the arteries, tightening them up to raise the pressure. The ace inhibitors can
bring blood pressure down quickly but in very rare cases can cause kidney damage or a
reduction in the number of white blood cells (leading to an increased susceptibility to
infection). Start at lower doses and increase until reach ideal BP.
-beta blockers: Block action of adrenalin (produced by adrenal glands and increases BP)
from entering receptor site. Reduce high bP by throttling back the force and speed of
the heart. They may also reduce BP by a direct effect on the body’s master controls, the
CNS. Side effects: bad dreams and muscle aches
-calcium channel blockers: Blockers act by dilating the arteries and reducing resistance
to the flow of blood. They have proved to be beneficial not only for high blood pressure,
but also for angina and other problems of a weakened heart. Some CCBs are now
available combined with an ace i