striated muscle heart muscle smooth muscle excitation contraction coupling

striated muscle

heart muscle

smooth muscle

excitation contraction coupling

Description of curvesDescription of curvesP = Impulse spread through atriaPQ = neutral (isoelectric) line after depolarisation of all atria myocardiumQRST = ventricle complexQ = negative oscillation – beginning of ventricle depolarisation in septumR = continue of depolarisation wave through the ventricleS = negative oscillation – activation of last part of ventricle myocardium in left ventricle base ST = neutral (isoelectric) line after ventricle depolarisation (plató phase in action potential)T = repolarisation from epicardium to endocardium

According to the amplitude, lower or upper case is used> 5 mm - Q, R, S< 5 mm - q, r, s

III

I

II

aVL

aVR

aVF

0o

+30o

+60o+90o+120o

+150o

+180o

-30o-150o

-120o

-90o

-60o

Action potentialAction potential

SA node Myocardium

Examples of pathological ECGExamples of pathological ECG

Sinusoidal rhythm and fibrilation of atria & AV block

Fibrilation of ventricles

Heart attack

AV block

1. Blokáda levého raménka Tawarova (BLRT) (synonymum: LBBB - left bundle

branch block)

According to the QRS interval      -complet block - QRS > 0,12s      -incomplet - QRS < 0,11s Incidence: heart attack (congenital LBBB extremely rare. aortal stenosis or diphteria)

Blokáda pravého raménka Tawarova (BPRT) (RBBB - right bundle branch block)

Incidence: RBBB heart attack, chronic cor pulmonale, atrium septal defect.incomplete RBBB normal in cyclist and boaters (volume load to right ventricle).

extrasystolesupraventricular

ventricular

reentry

ECG leads

R On the right arm, avoiding bony prominences – RED

L In the same location that RA was placed, but on the left arm this time – YELLOW

G On the right leg, avoiding bony prominences – BLACK (ground)

LL In the same location that G was placed, but on the left leg this time – GREEN

V1In the fourth intercostal space (between ribs 4 & 5) just to the right of the sternum

(breastbone).

V2 In the fourth intercostal space (between ribs 4 & 5) just to the left of the sternum.

V3 Between leads V2 and V4.

V4In the fifth intercostal space (between ribs 5 & 6) in the mid-clavicular line (the

imaginary line that extends down from the midpoint of the clavicle (collarbone).

V5 Between leads V4 and V6

V6Horizontally even with V4 and V5 in the midaxillary line. (The midaxillary line is the

imaginary line that extends down from the middle of the patient's armpit.)

LeadsLeads a andnd ele elecctrodtrodeses

Limb Thoracic

Evaluation of the Evaluation of the EECCGG

• Pulse: regular, irregular• Rhythm: sinusoidal or other (nodal = from AV

node)• Frequency: Normal 60-90 pulses/min• Heart electrical axis inclination: normal (the

same way), to left (outside), to right (inside) just generally from limb leads I and III. Exactly by using Einthoven’s triangle.

• Description of waves, their duration and intervals.

FreFrequequencncyy

• Heard frequency = 72 pulses/min, = pulse interval 0.83 s

• During relaxation the frequency changes based of the respiration (RESPIRATION ARYTMIA) = inspiration - increased frequency, expiration – decreased frequency.

• Bradycardia = fysiological = deep long-term inspiration, deep forward bend and knee band = reflex changes of vagal tonus.

• Tachycardia = fysiological = swallow (decrease of vagal tonus), change of position from lying or sitting to standing (ORTOSTATIC REACTION).

Examples of pathological ECGExamples of pathological ECG

Sinusoidal rhythm and fibrilation of atria & AV block

Fibrilation of ventricles

Heart attack

reentry

Electric expression of heart Electric expression of heart actionaction

• Record of summary electric activity of hear is called electrocardiogram (ECG).

• ECG curve is summary potential that is a result of all action potentials of myofibers.

• Beginnings of QRS complex and action potentials of ventricles are the same and ending of ventricle action potentials is the same as the end of wave T.

Ganong: Physiology

if positive in the lead aVF (above left) and

positive in the lead I (right)

then must lie where overlap (right)

heart electrical axisaverage (largest) electrical heart vector)

III

I

II

aVL

aVR

aVF

0o

+30o

+60o

+90o

+120o

+150o

+180o

-30o-150o

-120o

-90o

-60o

III

I

II

aVL

aVR

aVF

0o

+30o

+60o

+90o

+120o

+150o

+180o

-30o-150o

-120o

-90o

-60o

Lead I – positive amplitude

Lead I – negative amplitude

Heart electrical axis inclinationHeart electrical axis inclination

• Each myocyte produce dipole during action potential - vector with specific dimension and direction.

• Cell vector head from depolarised to polarised part, i.e. in direction of action potential spread.

• If the cell is completely depolarised (plató phase) or polarised (resting phase), vector is neutral.

• Electrical heart vector is a summary of all cell’s vectors in one time point

Normal value is -30° až +105° Shift of the axis to right above 105 ° = hypertrophy of RV or long and slim Shift of the axis to left below -30° = hypertrophy of LV or obese people