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Cardiac Cycle

Cardiac Cycle. 1. Ventricular Systole - Isovolumetric contraction - Ventricular ejection 2. Ventricular Diastole - Isovolumetric ventricular relaxation - Ventricular filling: Rapid inflow Diastasis

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Cardiac Cycle

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  1. Cardiac Cycle 1. Ventricular Systole - Isovolumetric contraction - Ventricular ejection 2. Ventricular Diastole - Isovolumetric ventricular relaxation - Ventricular filling: Rapid inflow Diastasis Atrial systole

  2. BP Checkpoints Systolic • 심실, 심방, 동맥내 압력. • 심실내 용적변화. • 판막의 여닫힘 시기. • 심음, EKG . Diastolic

  3. Ventricular volume change during cardiac cycle EDV SV ESV - Stroke Volume (SV) = EDV - ESV - Ejection fraction = SV/EDV : 50 - 60 % 심실근 수축성의 지표

  4. 심음 청진 부위 • Normal Heart Sound: S1, S2, (S3) • Abnormal Heart Sound (Murmur) • - timing: systolic/diastolic/continuous • - area

  5. 심근수축의 기본 형태 Afterload Preload

  6. Preload dependenceEDV 에 해당, venous return에 의해 결정됨.

  7. Afterload : Aortic Pressure에 해당

  8. 심장의 작업곡선 근수축의 길이-장력 관계 (length-tension) 심장에서는 압력-용적 관계 (pressure-volume) 로 나타냄

  9. End systole LV pressure End diastole LV volume Animal Experiment Measurement with Conductance Catheter LV pressure-volume loop LV volume LV pressure LV pressure

  10. 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

  11. The effect of increasing preload LV pressure LV volume

  12. 심장의 자동조절 기전: Frank-Starling 기전 • 용적부하 (preload) • 증가에 따른 반응 EDV SV • 압력부하 (afterload) • 증가에 따른 반응 SV EDV SV

  13. Contractility Indices peak dP/dt dP/dt/DP systolic ejection rate ejection fraction contractility Heart Disease, Braunwald, 5th edition

  14. Autonomic Nervous Control b1-adrenergic receptor Heart Heart Dorsal motor nucleus (cardioinhibitory center) Vagus nerve Muscarinic receptor

  15. Vagal stimulation Sympathetic stimulation

  16. Effect of autonomic nerve stimulation on SAN Sympathetic stim. Parasympathetic stim.

  17. Left Right Sympathetic parasympathetic SV Conduction velocity SV HR HR

  18. Effect of Autonomic Nervous System sympathetic parasympathetic SA Node AV Node Atrial myocardium Ventricular myocardium Positive chronotropic Positive inotropic Negative chronotropic Negative inotropic

  19. Signal transduction of ion channel regulation by autonomic stimulation sympathetic parasympathetic b-adrenergic receptor muscarinic receptor Gs protein Gi protein _ Adenylyl cyclase cAMP Protein kinase A Phospholylation of ICa & If Activation of IKACh

  20. Ion Channel Mechanism of Nervous System sympathetic parasympathetic ICa If IKACh ICa SA Node ICa If IKACh ICa AV Node ICa Atrial myocardium IKACh ICa ICa Ventricular myocardium Na pump

  21. 교감신경 흥분의 수축력에 대한 효과 Contractility 증가 교감신경 흥분, Ca 농도 증가 등의 조건에서 수축력 증가

  22. Cardiac factors Coupling factors Heart Rate Pleload Cardiac Output Myocardial Contractility Afterload

  23. Regulation of the heartbeat - Baroreceptor reflex - Bainbridge reflex - Chemoreceptor reflex - Respiratory sinus arrhythmia - Effect of blood or electrolyte solution infusion

  24. Coronary circulation

  25.  extracoronary resistance - squeezing effect of the contracting myocardium - left coronary flow : early ventricular systole 에 reverse; early diastole에 최대

  26.  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

  27. Ischemic Heart Disease 관상동맥 막힘 Ischemia(허혈), Infarction(경색) 세포내 ATP 감소 KATP Channel의 활성화 활동전압 duration 짧아짐, K의 유출로 세포밖 K 농도 증가 수축 감소로 energy saving의 효과 (cardioprotective) 동시에 부정맥 발생 위험 증가 (arrhythmogenic)

  28. 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 aldosterone분비 ) right shift of vascular function curve C.O은 정상일 수도 있음 Fig.29-12

  29. The effect of sympathetic stimulation on the equilibrium value of cardiac output and central venous pressure Fig. 29-10 Fig. 29-9

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

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

  32. Respiratory Center Change in intrathoracic pressure Change in lung volume (stretch receptor) Cardiac Vagal Center Heart Rate Change in venous return Bainbridge reflex Change in Arterial pressure Baroreceptor reflex

  33. Intravenous infusion Right atrial pressure Cardiac output Atrial receptor stimulated Arterial pressure Baroreceptor reflex Bainbridge reflex _ + Heart Rate

  34. Cardiac Output (C.O) = Stroke Volume (ml) x Heart Rate (/min) Fig. 29-16

  35. Left and Right Heart (Systemic vs. Pulmonary) Fig. 29-14 Fig. 24-19

  36. The effect of sympathetic stimulation on the equilibrium value of cardiac output and central venous pressure Fig. 29-10 Fig. 29-9

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