Cardiovascular-Anatomy and Physiology3.pdf

Cardiovascular-Anatomy and Physiology Cardiac Anatomy  Coronary Vessels Right coronary artery – Conus – Right marginal branch – Posterior descending branch Left coronary artery – Left anterior descending artery – Circumflex artery Collateral ar...

Cardiovascular-Anatomy and Physiology Cardiac Anatomy  Coronary Vessels Right coronary artery – Conus – Right marginal branch – Posterior descending branch Left coronary artery – Left anterior descending artery – Circumflex artery Collateral arteries Coronary capillaries Coronary veins – Coronary sinus – Great cardiac vein – Posterior vein of the left ventricle Coronary lymphatic vessels The heart is a multi-chambered dual cycle electrical pump The Cardiac Cycle Cardiac Cycle Sequence of events in one heart beat o Diastole o Systole Phases of the cardiac cycle o Atrial systole o Isovolumic contraction o Ejection o Isovolumic relaxation o Ventricular filling Electrical Circuit [Na+]=140 mEq/L K+=4.0 mEq/L 2K+ -80 mv 3Na+ K+ [K+]=120 mEq/L Na+=10 mEq/L Sinoatrial Node The Mechanical Pump Aka…Cardiomyocytes Steps in excitation-contraction coupling Integrated Function Flow (I)=P/R , I is synonymous with cardiac output, P-mean arterial pressure, and R=resistance Resistance = 8ηL πr4 r=radius, L=length, η=viscosity Thus resistance is linearly proportional to the length and viscosity, but inversely proportional to the 4th power of radius.  Cardiac Output (CO) CO=Stroke Volume (SV) x Heart Rate (HR) Liters/minute C.O. Pre-load (left vent. end-diastolic pressure)  Control of NORMAL Blood Pressure Cardiac output Peripheral vascular resistance – BP=CO x PVR Compliance  Regulation of NORMAL Blood Pressure Blood Pressure = Cardiac Output x Peripheral Vascular Resistance decreased decreased and/or decreased Response Sympathetic Activity HR, contractility Vasoconstriction Hormonal NO Epinephrine Natriuretic peptides Renin/angiotensin/aldosterone  Natriuretic peptides Atrial, Brain, Urodilantin, C-type peptide Secreted when atrium/ventricle stretched (increased volume) and from hypothalamus/kidney with volume expansion Inhibited by volume reduction 32 AA peptide with variation in C-terminal end  Renin/Angiotensin/Aldosterone Renin secreted by renal afferent and efferent arteriole when decreased stretch (volume depletion). Cleaves Angiotensinogen to angiotensin I. Also increased by β-adrenergic agonists or tubule delivery of chloride to macula densa in kidney. Angiotensin I converted to Angiotensin II by angiotensin converting enzyme (serine protease) Angiotensin II stimulates secretion of aldosterone by adrenal cortex and is potent vasoconstrictor. Aldosterone stimulates renal Sodium reabsorption.  Cardiovascular Disease Heart failure ASCVD/Coronary Artery Disease/Myocardial Infarction Electrical/Rhythm Valvular Genetic/Congenital Preload Afterload Backwards Heart Failure Forward Heart Failure Diastolic Dysfunction Systolic Dysfunction  Heart Failure Systolic (low cardiac output, decreased ejection fraction) Diastolic (Increased LVEDP), preserved ejection fraction Ejection fraction-percent of each left ventricular volume ejected during systole.  Etiologies of Heart Failure Hypertension Ischemic injury Valvular disease Genetic Myocarditis – Viral – Auto-immune-vasculitis Nutritional – Vitamin deficiency – Alcoholic Hormonal – Thyroid C.O. dP/dT=acceleration of contraction Pre-load (left vent. end-diastolic pressure)  Forward Heart Failure (systolic dysfunction, low ejection fraction) Decreased BP and renal blood flow Increased renal sympathetic nerve activity (Na retention) Increased LVEDV-normalized C.O.  Backward Heart Failure (venous hypertension) Increased capillary fluid exit/Decreased intra- vascular volume Increased renal sympathetic activity Renal Na retention  Baroreceptor Activity Decreased cardiac output Decreased velocity of stretch of baroreceptor Increased renal sympathetic activity Renal Na retention  Myocardial Remodeling Hypertrophy Nutrient/Oxygen delivery Atrophy, apoptosis  ASCVD Coronary Artery Disease Peripheral Arterial Disease (PAD) Cerebral Vascular Disease Abdominal Vascular Disease  Diseases of the Arteries Atherosclerosis – Form of arteriosclerosis – Thickening and hardening is caused by accumulation of lipid-laden macrophages in the arterial wall – Plaque development – Progression Inflammation of endothelium Cellular proliferation Macrophage migration LDL oxidation (foam cell formation) Fatty streak Fibrous plaque Complicated plaque Atherosclerosis Atherosclerosis  Coronary Artery Disease (CAD) Any vascular disorder that narrows or occludes the coronary arteries Atherosclerosis is the most common cause Risk factors – Dyslipidemia – Hypertension – Cigarette smoking – Diabetes mellitus – Obesity/sedentary lifestyle – Chronic Kidney Disease  CAD Features that argue strongly against coronary Symptoms Fleeting pain (