Cardiac Cycle

1. Ventricular Systole - Isovolumetric contraction - Ventricular ejection

2. Ventricular Diastole - Isovolumetric ventricular relaxation - Ventricular filling: Rapid inflow Diastasis Atrial systole

Systolic

Diastolic1. 심실 , 심방 , 동맥내 압력 .2. 심실내 용적변화 .3. 판막의 여닫힘 시기 .4. 심음 , EKG .

CheckpointsBP

Ventricular volume change during cardiac cycle

- Ejection fraction = SV/EDV : 50 - 60 % 심실근 수축성의 지표

EDV

ESV

SV

- Stroke Volume (SV) = EDV - ESV

심음 청진 부위

• Normal Heart Sound: S1, S2, (S3)

• Abnormal Heart Sound (Murmur) - timing: systolic/diastolic/continuous - area

심근수축의 기본 형태

AfterloadPreload

Preload dependenceEDV 에 해당 , venous return 에 의해 결정됨 .

Afterload : Aortic Pressure 에 해당

심장의 작업곡선근수축의

길이 - 장력 관계(length-tension)

심장에서는압력 - 용적 관계(pressure-volume)

로 나타냄

Animal Experiment Animal Experiment Measurement with Conductance CatheterMeasurement with Conductance Catheter

LV volume

LV pressure

LV volume

LV p

ress

ure

End diastole

End systole

LV p

ress

ure

LV pressure-volume loop

Regulation of myocardial performance

Intrinsic regulation (autoregulation) - Frank-Starling mechanism - Rate-induced regulation

Extrinsic regulation - Autonomic nervous system - Endocrine control : adrenal medullary hormone thyroid hormone, insulin, glucagon - 기타 : PO2, PCO2, pH

The effect of increasing preload

LV p

ress

ure

LV volume

• 용적부하 (preload)증가에 따른 반응

• 압력부하 (afterload)증가에 따른 반응

심장의 자동조절 기전 : Frank-Starling 기전

SV EDV SV

EDV SV

Contractility Indices

ejection ejection fractionfraction

peak dP/dtpeak dP/dt

systolic systolic ejection rateejection rate

contractilitycontractility

dP/dt/DPdP/dt/DP

Heart Disease, Braunwald, 5th edition

Heart

Heart

Vagus nerve Muscarinic receptor

-adrenergic receptor

Dorsal motor nucleus(cardioinhibitory center)

Autonomic Nervous Control

Vagal stimulation

Sympathetic stimulation

Effect of autonomic nerve stimulation on SAN

Sympathetic stim.

Parasympathetic stim.

Left RightSympatheticparasympathetic

SVConduction velocity

SV HRHR

Effect of Autonomic Nervous System

sympathetic parasympathetic

Atrial myocardium

AV Node

SA Node

Ventricular myocardium

Positive chronotropicPositive inotropic

Negative chronotropicNegative inotropic

Signal transduction of ion channel regulationby autonomic stimulation

sympathetic parasympathetic

Phospholylation of ICa & If Activation of IKACh

-adrenergic receptor

Adenylyl cyclase

cAMP

Protein kinase A

muscarinic receptor

Gs protein Gi protein_

Ion Channel Mechanism of Nervous System

sympathetic parasympathetic

Atrial myocardium

AV Node

SA Node

Ventricular myocardium

ICa If

ICa

ICa

IKACh ICa

IKACh ICa

IKACh ICa

Na pump

ICa If

Contractility 증가

교감신경 흥분의 수축력에 대한 효과

교감신경 흥분 , Ca 농도 증가 등의 조건에서 수축력 증가

CardiacOutput

Heart Rate

MyocardialContractility

Pleload

Afterload

Cardiac factors Coupling factors

Regulation of the heartbeat

- Baroreceptor reflex- Bainbridge reflex- Chemoreceptor reflex

- Respiratory sinus arrhythmia- Effect of blood or electrolyte solution infusion

Coronary circulation

extracoronary resistance

- squeezing effect of the contracting myocardium - left coronary flow : early ventricular systole 에 reverse; early diastole 에 최대

Autoregulation 발달 - change of perfusion pressure : blood flow 비교적 일정하게 유지 - metabolic demands 증가 vasoactive metabolites released from myocardium coronary resistance 감소 - adenosine hypothesis 가 가장 유력

Ischemic Heart Disease

관상동맥 막힘

Ischemia( 허혈 ), Infarction( 경색 )

세포내 ATP 감소

KATP Channel 의 활성화

활동전압 duration 짧아짐 , K 의 유출로 세포밖 K 농도 증가

수축 감소로 energy saving 의 효과 (cardioprotective) 동시에 부정맥 발생 위험 증가 (arrhythmogenic)

Heart Failure- 정의 : Pumping capability of the heart is impaired to the point that the tissues of the body are not adequately perfused.- Acute or Chronic

- In chronic H. F., fluid retention (hypervolemia)

is accompanied. (GFR aldosterone 분비 )

right shift of vascular function curve

C.O 은 정상일 수도 있음 Fig.29-12

Fig. 29-9Fig. 29-10

The effect of sympathetic stimulation on the equilibrium value of cardiac output and central venous pressure

Effect of cholinergic blocker (atropine) and adrenergic blocker (propranolol) on heart rate

Respiratory sinus arrhythmia : inspiration - HR (vagal activity ) expiration - HR (vagal activity )

Respiratory Center

Change inintrathoracic

pressure

Change invenous return

Bainbridge reflex

Heart Rate

Change inlung volume

(stretch receptor)

Change inArterial pressure

Baroreceptor reflex

CardiacVagal Center

Intravenous infusion

Right atrial pressure

Atrial receptor stimulated

Bainbridge reflex

Heart Rate

Cardiac output

Arterial pressure

Baroreceptor reflex

+ _

Cardiac Output (C.O) = Stroke Volume (ml) x Heart Rate (/min)

Fig. 29-16

Left and Right Heart (Systemic vs. Pulmonary)

Fig. 24-19Fig. 29-14

Fig. 29-9Fig. 29-10

The effect of sympathetic stimulation on the equilibrium value of cardiac output and central venous pressure