Coronary Artery System:
Coronary Artery System CORONARY CIRCULATION – 1 st branches of aorta Right coronary artery – supply right heart, posterior left ventricle and conduction system ( if blocked, worse than left coronary artery ) Left Coronary Artery – anterior wall of left ventricle, and anterior septum Clinical importance 1 : right coronary artery blockage ischemia of conductive system ( S.A n A.V node ) bradycardia + AV nodal block Clinical importance 2 : left coronary artery blockage left ventricle infarction can’t pump out blood ( pump failure ) 3 important arteries : LCX, RCA, and LAD
IHD:
IHD Imbalance between perfusion and demand of cardiac myocytes Commonest cause : coronary artery atherosclerosis Others : spasm, embolus, thrombosis, coronary arteritis + reduced 02 in blood ( anemia, carboxyhemoglobinemia ) + reduced blood flow ( hypotension ) 4 clinical syndromes : 1 ) Angina Pectoris ( stable, variant, unstable ) 2) Acute MI 3) Chronic IHD – heart failure 4) Sudden Cardiac Death – SCD Epidemiology : common in those with risk factors of atherosclerosis ( DM, HPT, chronic smoker, family history 1 st degree relative , obese, hyperlipidemia )
pathogenesis:
pathogenesis Acute Plaque Changes – ruptures , fissuring, exposing thrombogenic subendothelial expansion total block SCD or acute MI Vasoconstriction – further compromise blood flow + cause plaque rupture .caused by sympathethic , endothelin ( that’s y don’t watch horror movie !) Myocardial Hypertrophy - increase demand ischemia ( viscious cycle )
Angina Pectoris:
Angina Pectoris Definition : intermittent chest pain caused by transient , reversible Myocardial ischemia 3 types : Stable, Prinzmental , Unstable Stable / typical : fixed narrowing / stable atherosclerotic plaque.due to increase in myocardial demand ( fever, tachycardia, emotion , exertion ) Prinzmetal / Variant : at rest – coronary spasm – can affect both normal or narrowed vessels Unstable – part of ACS , pre-infarction , plaque disruption + vasospasm+ MOST SEVERE FORM OF ANGINA Roles of GTN in relieving angina attack – 2 : venodilator reduced VR reduce work load reduced myocardial demand At hi dose : vasodilate coronary artery – improve flow No sympathetic , relieved by GTN ( MI pain alleviated by morphine ) usually angina attack
Chronic IHD:
Chronic IHD Post – MI heart failure / ischemic cardiomyopathy Left ventricular dilatation / hyperthrophy arrythmia & recurrent MI and angina VISCIOUS CYCLE
SCD:
SCD 1-24 hrs after onset of symptoms Cardiac causes Younger patient – congenital / genetics Common causes : atherosclerosis of CA Examples of non-atherosclerotic causes : - Valve problem : Pressure overload ( AS ) , Volume Overload ( MR ) - myocardial probs : HOcM , myocarditis - Patho : arrthymia : V-Fib