5. Monitoring the performance of the heart

Heart rate, pulse rate, audio examination with stethoscope

Monitoring heart rate and blood pressure

Monitoring the condition and effectiveness is very important for the prevention and diagnosis of adverse heart conditions.

Blood pressure - the pressures created in your bloodstream by the pumping action of the heart.

Blood pressure (BP) is normally quoted with 'old' barometric height units of mm Hg (millimetres of mercury). There are two possible blood pressure readings:

Systolic BP (higher number) - the pressure created by the heart muscles in pumping blood out.

Diastolic BP (lower number):- the pressure in your heart, at rest between beats.

If the readings are higher than they should be, you may be suffering from hypertension and require further medical examination. This may caused by e.g. damaged heart muscle or partially blocked arteries, whatever, the situation needs seeing to!

 

Pulse rate - this is the rate at which your heart is beating e.g. normally 60-100 per minute.

The pulse is caused by the alternating increase in blood pressure as you heart pumps the blood around in you blood vessels. (It does not necessarily correlate with blood pressure)

The heart works on an autonomic muscle system and should beat at a steady rate, but increases with increase in more aerobic physical activity.

If under normal sedentary conditions it is too low or too high, it might indicate a heart problem.

For healthy people it tends to lower the older you get, but it tends to be lower for more aerobically fit people - regular exercise is good for your heart.

 

Audio examination - You listen to the sounds of the heart valves opening and closing using a stethoscope.

You can hear each individual valve of the heart opening and closing.

Any abnormality in the expected pattern can be picked in the audio output.

 

Electrocardiogram (ECG) - is a simple test that can be used to check your heart's rhythm and electrical activity.

Electrocardiography is the production of an electrocardiogram, a recording of the heart's electrical activity through repeated cardiac cycles of the heart as it pumps blood around the body.

The electrocardiogram of the heart is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin

The electrode sensors attached to your skin detect the electrical signals produced by your heart every time it beats.

These ECG signals are recorded by a machine and are looked at by a doctor to see if there is anything unusual in the pattern.

An ECG may be requested by a heart specialist (cardiologist) or any doctor who thinks you might have a problem with your heart.

You can perform an ECG just resting or doing a more aerobic exercise.

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Key points - Summary of ideas

Based on the syllabus-specifications for students taking the AQA, Edexcel and OCR GCSE level biology examinations (~US grades 9-10).

Measuring the Performance of the Heart – Revision Notes

Blood Pressure (BP)

Blood pressure is the force exerted by circulating blood against the walls of arteries.

It is measured in millimeters of mercury (mmHg) using a sphygmomanometer.

• Systolic Pressure: The pressure when the heart contracts (higher value).

• Diastolic Pressure: The pressure when the heart relaxes (lower value).

• Normal BP: Around 120/80 mmHg.

• High BP (Hypertension): Can increase the risk of heart disease and stroke.

• Low BP (Hypotension): Can lead to dizziness and fainting due to poor blood circulation.

Pulse Rate

Pulse rate measures the number of heartbeats per minute (bpm) and is assessed by feeling the pulse at the wrist or neck.

• Normal Resting Pulse Rate: Around 60–100 bpm (lower for athletes).

• Tachycardia: High pulse rate (above 100 bpm) – may indicate stress, fever, or heart issues.

• Bradycardia: Low pulse rate (below 60 bpm) – can be normal in athletes but may indicate heart conditions in other individuals.

Audio Examination (Stethoscope)

A stethoscope allows healthcare professionals to listen to heart sounds.

• Heart Sounds: "Lub-dub" sounds caused by the closing of heart valves.

• Abnormal Sounds (Murmurs): May indicate valve defects or other heart conditions.

Electrocardiogram (ECG)

An ECG records the electrical activity of the heart and is displayed as a graph.

• P Wave: Atrial contraction.

• QRS Complex: Ventricular contraction.

• T Wave: Ventricular relaxation.

• Uses of ECG:

  • Diagnosing arrhythmias (irregular heartbeat).

  • Identifying heart attacks (changes in ECG pattern).

Other Methods to Monitor the Heart

• Echocardiogram (Ultrasound): Uses sound waves to create images of the heart, showing how it pumps.

• Cardiac MRI: Provides detailed heart images using magnetic fields.

• Stress Testing: Observes heart function during exercise.

• Holter Monitor: A continuous ECG recording for 24+ hours.

• Blood Tests: Measure markers like troponin to detect damage to heart muscle.

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The focus of this topic is the function and importance of each method of monitoring the heart and its health!

Be prepared to analyze graphs, interpret data, and explain heart abnormalities.

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Summary of learning objectives and key words or phrases

Be able to explain what an electrocardiogram ECG is.

Be able describe ways of monitoring heart function and performance.

Be able to describe and understand a heart audio examination with a stethoscope, measurement of heart beat patterns, measuring pulse rate and measurement of blood pressure.

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