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coronary circulation satty (31.1.25).pptx
- 1.
- 2. CORONARY CIRCULATION • Coronaryblood vessels • Special features of CBF • Regulation of CBF • Applied
- 3. CORONARY CIRCULATION Refersto the blood flow to the heart. Heart weighs about 300 g. CBF is approximately 250 ml/min Heart is supplied by two coronary arteries right and left.
- 5. CORONARY CIRCULATION • Leftand right coronary arteries originate at the root of the aorta behind aortic valve. • Left main coronary divides into left anterior descending and circumflex branches.
- 6. CORONARY CIRCULATION Right coronaryartery supplies – Right atrium. – Right ventricle Left coronary artery supplies – Left atrium – Left ventricle
- 8. CORONARY CIRCULATION Venous drainage Superficialsystem Coronary sinus Anterior cardiac vein Deep system Thebesian vessels
- 9. SPECIAL FEATURES OFCORONARY CIRCULATION • Coronary flow is more during diastole. • Coronary flow is reduced during systole as pressure in ventricle is more than pressure in the aorta during systole.
- 12. SPECIAL FEATURES OFCORONARY CIRCULATION • Coronary arteries are functional end arteries; therefore blockage of coronary arteries results in ischemia/ infarction of cardiac muscle. • Metabolic regulation of coronary circulation is well developed
- 13. SPECIAL FEATURES OFCORONARY CIRCULATION • CBF depends on cardiac activities. Hence, during exercise CBF can be increased 4 to 5 folds to meet the oxygen demand by the cardiac muscle. • Veins drain directly into the chambers adding deoxygenated blood to the oxygenated blood (Physiological shunt).
- 14. REGULATION OF CORONARYCIRCULATION 1.Neural regulation 2.Metabolic factors 3.Autoregulation
- 15. 1. NEURAL REGULATION •Parasympathetic stimulation - vasodilation • Sympathetic stimulation causes vasoconstriction everywhere but cause coronary vasodilation Reason: • Sympathetic stimulation increases the heart rate and force of contraction • This in turn increases oxygen demand leading to hypoxia, PCO2 & H+ which cause coronary vasodilation.
- 16. 2. METABOLIC REGULATION •Blood flow decreases • decreased oxygen supply results in formation of vasodilator metabolites • In coronary occlusion, accumulation of adenosine, CO2, H+ , K+ , Lactic acid, PG , NO coronary vasodilatation occur leading to Reactive hyperemia
- 17. 3. AUTOREGULATION • Capacityof tissues to regulate their own blood flow • Maintain blood flow within the pressure range of 70- 110mmHg
- 19. Applied MYOCARDIAL ISCHAEMIA Occurs whenlumen reduced to ¾th MYOCARDIAL INFARCTION Complete occlusion of a large coronary artery leading to necrosis of the tissue supplied.
- 20. Applied – Chest Painthat comes from ischemic myocardium due to stimulation of the free nerve endings by substances like histamine, substance P and other chemicals. – Usually referred to the medial surface of the left arm. – Both heart & left arm develops from same embryonic segment
- 21. Applied Diagnosis • Increased levelof serum enzymes like CK-MB, Troponin-T, Troponin- I • ECG: ST segment elevation & T wave inversion- Myocardial Infarction • Coronary angiography
- 22. Applied MEDICAL TREATMENT: – Thrombolyticdrug (t-PA, Streptokinase) – Heparin (Anticoagulant) – Aspirin ( prevent the reoccurrence of clots ) – Nitrates (coronary vasodilators) – Calcium channel blockers (decreases myocardial contractility) – β blockers ( reduce O2 consumption)
- 23. Applied SURGICAL TREATMENT – Coronaryangioplasty – Coronary bypass surgery
- 24. 1.Which of thefollowing is not a feature of Coronary circulation a.Sympathetic stimulation of coronary vessels causes vasodilation b.Sub endocardial portion is less prone to ischemia c.Coronary arteries are end arteries
- 25. 2.Identify the correctstatement a.Heart receives major blood supply during systole b.Heart receives major blood supply during diastole c.Blood supply remains constant during both phases of cardiac cycle
- 26. 3.Which of thefollowing is not a metabolic vasodilator in heart a.Serotonin b.Adenosine c.Potassium
- 27.