CARDIAC MECHANICS
CARDIAC CYCLE
HEART FAILURE
PASSIVE STRETCH ACTIVE STRETCH
STARLING PRINCIPLE (heterometric autoregulation)
AFTERLOADED CONTRACTION PRELOAD, AFTERLOAD
Length – tension relationship
EJECTION FRACTION
LAPLACE LAW
T = P. r / h
P = T . h / r
HYPERTROPHY
1. T = VO2
2. h
I. III.II. IV.
I. – mitral (+ tricuspidal) valve closure
II. - aortal (+ pulmonary) valve closure
III. - fast filling of ventricles - pathological
IV. - contraction of atria – mostly pathological
Caused by vibration of:
•Closure and stretching of
valves
•Izovolumic contraction of heart
muscle (papill. muscles, tendons)
•Turbulent blood flow
Vibration of ventricular wall
HEART SOUNDS
MURMURS – pathological phenomena
1. SYSTOLIC:
• Stenosis – aortal, pulmonary (1)
• Regurgitation – mitral, tricuspidal (2)
2. DIASTOLIC:
• Stenosis – mitral, tricuspidal (3)
• Regurgitation – aortal, pulmonary (4)
3. SUSTAINED:
• Defects of septum I. III.II. IV.
Splitting of I. or II. sound:
asynchronous closure of
M - T valve (I.)
or Ao - P valve (II.)
(inspiration,
hypertension….)
TURBULENT BLOOD FLOW
CARDIAC OUTPUT
CO
HR
SV
CO = HR x SV
CORONARY
FLOW
EDV
Venous return
Compliance
Aortal pressure
LV = RV
Starling law
Frequency
effect
sympathetic, parasympathetic stimulation
SV = EDV - ESV
EF = EDV – ESV / EDV
5l/min
70ml
>60%
CARDIAC RESERVE = maximal CO / resting CO
CORONARY RESERVE = maximal CF / resting CF
CHRONOTROPIC RESERVE = maximal HR / resting HR
VOLUME RESERVE = maximal SV / resting SV
CARDIAC INDEX = CO / body surface
4 - 7
3,5
3 - 5
1,5
POLYGRAPHY (polygram)
CARDIAC RESERVE
CO (l/min)
WORKLOAD (W/kg)
ATHLETHS HEART
PHYSIOLOGICAL RESPONSE
HEART FAILURE
1 2 3 4
10
30
20
HEART FAILURE
The heart is not able pump sufficient amount of blood into periphery at normal
venous return.
MOST OFTEN CAUSES:
• Severe arrhythmias
• Overload – volume (aortal insufficiency, a-v shunts) or pressure (hypertension
and aortal stenosis – left overload, pulmonary hypertension and stenosis of
pulmonary valve – right overload)
• Cardiomyopathy
SYMPTOMS: fatigue, oedemas, venostasis, dyspnoea, cyanosis
ACUTE x CHRONIC. COMPENSATED x DECOMPENSATED.