Electrocardiography (ECG) and blood pressure

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EKG gyakorlat

Human circulation pulmonary circulation

left

right atrium

right

right ventricule

atrium

left

left ventricule

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systemic circulation

EKG gyakorlat

right atrium Cross-section of the human heart

left atrium

bicuspid valves

right ventricule

left ventricule

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EKG gyakorlat

Conduction system of the heart Frontal plane

Left atrium

Right atrium

1 SINOATRIAL (SA) NODE 2 ATRIOVENTRICULAR (AV) NODE

3 ATRIOVENTRICULAR (AV) BUNDLE (BUNDLE OF HIS)

4 RIGHT AND LEFT BUNDLE BRANCHES

Right ventricle

5 PURKINJE FIBERS

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Left ventricle

EKG gyakorlat

Einthoven 1895: description of the characteristic ECG waves 1912: declaration of the Einthoven triangle 1924: Nobel Prize

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Standard ECG recording

• human body is a good volume conductor (~70% contains water and ions) -> electrical activity generated by the heart can be recorded on the

surface of the skin: electrocardiography (ECG)

• characteristic waves during a heart cycle: P wave, QRS complex, T wave • provides information about: - generation and conduction of

action potentials; heart rate - problems with pacemaker activity - loss / damage to the conductive system or to cardiac muscle (myocardial infarct)

• does NOT provide information about: - pressure changes, ejected blood

volumes, force generated by cardiac muscle, etc

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Cardiac cycle

1 Depolarization of atrial contractile fibers

produces P wave

events and the

electrocardio- gram (ECG)

6 Ve6ntricular diastole (relaxation)

P

0 0.2 0.4 0.6 Seconds

5 Repolarization of5 ventricular contractile

fibers produces T wave

T

P

Action potential in SA node

0 0.2

Seconds

0.8

2 Atrial systole (contraction)

P

0 0.2 Seconds

3 Depolarization of ventricular contractile

fibers produces QRS complex

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P

4 Ventricular 0 0.2 0.4 0.6 systole

Seconds (contraction)

P

0 0.2 0.4 Seconds

R

P

Q S

0 0.2 0.4 Seconds

EKG gyakorlat

Standard ECG recording

atrial contraction

ventricular contraction

ventricular repolarization

atrial depolarization

ventricular depolarization

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(and atrial repolarization) EKG gyakorlat

Unipolar ECG leads

aVR aVL

V1 V2 V3

V4 V5 V6

6 unipolar chest leads (Wilson type)

aVF

3 unipolar (Goldberger-type) limb leads

+ V

aVR

1

V6 -

6 V2

2 V55

V3 V4

3 4 aVL

aVF

+ -

+ -

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EKG gyakorlat

Standard bipolar ECG leads (Einthoven type)

right arm

I

right leg

right arm

II

right leg

III

right leg

left arm

left leg

left arm

left leg

+ -

+ -

+ -

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EKG gyakorlat

Einthoven's law and the mean electrical

axis of the heart

Lead I + Lead III = Lead II

É

right arm

II

I -+

III

left leg

left arm mm

- -

mm

II +

I

+ -

mm

+ III

How to plot the mean electrical axis of

the heart?

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EKG gyakorlat

Deviations in the mean electrical axis of

the heart

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EKG gyakorlat

Characteristic ECG curves Normal sinus arrhythmia (respiratory sinus arrhythmia)

inhalation

22 years

79 years

time (s)

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EKG gyakorlat

Extrasystole

atrial

sinoatrial

ventricular

repeated ventricular

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early, abnormal P wave

early P wave

long, deformed QRS

EKG gyakorlat

Abnormal arrhythmias

atrial flutter (200-300 bpm)

atrial fibrillation

(300-500 bpm)

ventricular flutter

ventricular

fibrillation

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EKG gyakorlat

Infarct

early

1-6 h

2-3 weeks

3-5 months

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• elevated T wave

• unidirectional elevation • decreased Q, R amplitude

• negative T wave • increased Q amplitude • decreased R amplitude

• large Q (>1/3 QRS ampl.) • positive T wave • normal R amplitude • normal ST period

Pacemaker

EKG gyakorlat

Regulation of cardiovascular activity nervous system:

hormones:

• epinephrine, norepinephrine, thyroid hormon: increase heart rate and contractility cations:

• K+, Na+, Ca2+ plasma levels influence contractility

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EKG gyakorlat

Baroreceptors in the human body and

innervation of the heart

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EKG gyakorlat

Regulation of blood

pressure via

baroreceptor reflexes

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Blood pressure measurement

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Tasks during the practicum

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EKG gyakorlat

ECG I (Lesson 5)

Effects of breathing, physical activity and circulatory reflexes on heart function

Carry out short (20-30 sec) ECG recordings in the following order:

1. Baseline registration (seated, normal breathing activity) 2. Seated, deep inhalation - deep exhalation (respiratory arrhythmia) • don't forget to mark the onset of inspiration on the recordings (F9)

• recording should last at least for two complete respiratory cycles

4. Immediately before and after physical activity (in sitting position)

3. Before, during and after sudden stand-up from lying position

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EKG gyakorlat

Blood pressure

Define your blood pressure (systolic / diastolic) and pulse rate on your left arm :

1. lying down 2. sitting 3. standing 4. before and after exercise (e.g. 20 push-ups)

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EKG gyakorlat

Effects of body postures and physical activity on circulation