Review of Cardiac AnatomyInternal Structure of heartImportance of ValvesChordae TendineaePath of Blood Through HeartCirculatory RoutesReview of Cardiac ConductionPacemaker Potentials and Cardiac Action PotentialsTiming and Route of Cardiac Action PotentialSystole and DiastolePressure Flow RelationshipsCardiac CycleCardiac OutputCardiac OutputRegulation of Stroke VolumePreloadEnd Diastolic VolumeContractilityAfterloadRegulation of Heart RateNervous Regulation of Heart RateThe ECGPrinciples of Biomedical Systems & DevicesPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Principles of Biomedical Systems & DevicesLecture 8: Cardiovascular DynamicsDr. Maria TahamontPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Review of Cardiac Anatomy Four chambers  Two atria-receive blood from the vena cave and pulmonary veins Two ventricles-pump blood out of the heart in the aorta and pulmonary arteries Four valves-tricuspid and mitral (bicuspid) and aortic and pulmonary semi lunarPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Internal Structure of heartPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Importance of Valves The cusps of the valves point in the direction of flow from atria to ventricles and ventricles to arteries. Valves guarantee that the blood flows in one direction Valves prevent back flow Chordae tendineae prevent the cusps of the atrioventricular valves from opening into the atria during ventricular contractionPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Chordae TendineaePBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Path of Blood Through HeartVena Cava Right AtriumBody Tricuspid V.Aorta Right VentricleAortic Semi lunar V. Pulmonary Semi lunar V.Left Ventricle Pulmonary ArteryMitral (bicuspid) V. LungsLeft Atrium Pulmonary veinsPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Circulatory RoutesThere are two circulatory routesª The Systemic Circulation delivers oxygenated blood to the body systemsª The Pulmonary Circulation delivers deoxgenated to the lungsª This design allows the delivery of adequate oxygen to the body while an equal amount of blood is being re-oxygenated in the lungsPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Review of Cardiac Conduction  Sinoatrial Node (natural pace maker) Atrioventricular node Atrioventricular Bundle (Bundle of His) Right and Left Branch Bundles Purkinji Fibers Remember that cardiac cells are self excitatory, they spontaneously depolarizePBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Pacemaker Potentials and Cardiac Action PotentialsPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Timing and Route of Cardiac Action PotentialPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Systole and Diastole The electrical events in the heart lead to mechanical event Systole-contraction Diastole-relaxation The point of contraction is to generate pressure Pressure gradients across the valves control blood flow from onearea to anotherPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Pressure Flow Relationships When pressure in the atria exceeds pressure in the ventricles the atrioventricular valves open and blood flows from atria to ventricles When ventricular pressure exceeds atrial pressure the atrioventricular valves close to prevent back flow When ventricular pressure exceed arterial pressure blood flows from ventricles to arteries When arterial pressure exceed ventricular pressure the semi lunar valves close preventing back flowPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Cardiac CyclePBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Cardiac Output Cardiac Output (CO) is the volume of blood ejected by the left ventricle into the aorta each minute Cardiac Output = Stroke Volume x Heart Rate Stoke Volume (SV) is the amount of blood ejected per beat Heart rate (HR) is the number of beats/minPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Cardiac OutputCO (ml/min) = SV (ml/beat) x HR (beats/min)= 70 (ml/beat) x 75 (beats/min)= 5250 ml/minHeart rate depends on the demands of the body, HR is elevated or depressed depending on needsStroke Volume depends primarily on how much blood has returned to the heartCardiac Output is regulated the factors that effect both HR and SVPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Regulation of Stroke Volume There are 3 factors that effect Stroke Volume:ª Preload – the degree of stretch on the heart before it contractsª Contractility – the forcefulness of contraction of individual ventricular muscle fibersª Afterload – the pressure that must be exceeded before blood can be ejected from the ventriclesPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Preload The greater the preload (stretch) the greater the force of contraction The more the heart fills during diastole, the greater the force of contraction during systole (Frank-Starling Law of the Heart) The preload is proportional to the volume of blood in the ventricle at the end of diastole (end diastolic volume)PBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404End Diastolic Volume Two factors effect end diastolic volume (EDV)ª The length of ventricular diastole- how long it takes to fill the ventricle-this depends on heart rateª Venous return – the volume of blood that returns to the right atriumThe same volume of blood flows to both the systemic and pulmonary