Download Option D: Blood pressure and heart disease

The stethoscope…
‘I see the chest’
Listening to the heart sounds
Alternatives to the stethoscope?
Accuracy of heart rate monitors
Option D: Blood pressure and
heart disease
Blood pressure
Blood pressure
Systolic:
• the maximum arterial pressure during
contraction of the left ventricle of the heart
Diastolic
• the minimum arterial pressure during
relaxation and dilatation of the ventricles of
the heart when the ventricles fill with blood
Blood pressure
Measuring blood pressure
• Using sound (Doppler Effect)
• Using electronics – non-invasive blood
pressure (cuff technology)
• BOTH methods use a cuff in order to block
blood flow transiently in an artery
• Then sound or ‘oscillometry’ is used to
produce a quantitative measurement
Doppler (sound) techniques
Oscillometric blood pressure
measurement
Control of blood pressure
• Think of some reasons why blood pressure
might rise or fall?
Many factors impact on blood
pressure
Cardiac output
• Cardiac output = volume of blood pumped by
the heart (in L/minute)
• Cardiac output is is the product of HEART
RATE (BEATS/MINUTE) and STROKE VOLUME
(ml/BEAT)
• Cardiac output can thus be increased by
increasing heart rate (within limits) OR stroke
volume
Tissue oxygen delivery:‘the bottom
line’
• depends on cardiac output (cardiac function and
forward flow) and arterial oxygen content (CaO2)
• Oxygen delivery (DO2) = cardiac output multiplied by
the oxygen content of blood
DO2= CO X [Hb] X SpO2 X 1.34
(each 1 g of haemoglobin can carry 1.34 g of oxygen)
Cardiovascular disease
1. Arrhythmia (e.g. ventricular fibrillation)
2. Thrombosis
3. High blood pressure (hypertension)
4. Coronary heart disease
When thinking about heart disease, remember
the principal aim of the whole system is oxygen
delivery to the tissues…
Coronary heart disease
The heart muscle is nourished by the
coronary arteries
Taking a look at coronary arteries…
Venous and arterial emboli
• When venous return is
impaired (e.g. long time
spent sitting and not
moving), blood flow can
slow down in certain veins.
• A clot may then form, called
an embolus
• If the clot breaks and moves
to the lungs, it can block in
the pulmonary arterioles –
pulmonary embolism,
which can cause death
serena williams embolism
Coronary (and other) arteries can be
narrowed by plaques, leading to sclerosis
and thrombosis
• Sclerosis: abnormal thickening or hardening
– Arteriosclerosis:….
• Thrombosis: localised clotting of blood in a region
of the cardiovascular system.
• A thrombus is a mass of platelets and fibrin that
forms locally in a vessel
– Deep venous thrombosis
– Coronary thrombosis
• Embolus – a piece of a thrombus that has broken
free and lodged in a blood vessel
Coronary heart disease
Coronary artery disease is diagnosed
by angiography…
What do you know of as risk factors in
coronary heart disease?
How do we study risk factors in heart
disease? The epidemiology of hert
disease…
• Epidemiology (Greek):
– :epi – upon/ Demos: The people/ Logos: the study
of
– The basic science of ‘public health’
– The branch of medicine that deals with the
incidence, transmission and control of disease
Epidemiology I: Risk factors for heart
disease
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Age
Gender
Exercise
Body mass
Diet
Smoking
Stress
Genetic predisposition
Epidemiology II: Factors which reduce
incidence of heart disease…