Introduction to hemodynamic and electrophysiology of heart.pptx

Introduction to hemodynamic and electrophysiology of heart.pptx

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  JULY 29, 20261 Dr. Rajendra Gode Institute of Pharmacy, University - Mardi Road, Amravati - 444602 Pharmacology – II (BP 503 T) “Pharmacology of drugs acting on CVS” a. Introduction to hemodynamic and electrophysiology of heart 1 Presented by Ms. Shraddha S. Raut M. Pharm (Pharmacology) Assistant Professor UNIT I
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  JULY 29, 20262 Hemodynamic Electrophysiology of Heart Cardiovascular System 1 3 2  Contents
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  JULY 29, 2026 Cardiovascular System 3 General Pharmacology • CVS stands for Cardiovascular System, where “cardio” means heart “vascular” means vessel • It is also known as the circulatory system. • The circulatory system is responsible for transporting blood throughout the entire body. • Blood carries oxygen (O2) and nutrients to the body, with oxygen being essential for respiration. • The heart pumps blood throughout the body via blood vessels. • The heart is interconnected with the blood vessels.
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  JULY 29, 20264 Blood Circulation in body via Heart
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  JULY 29, 20265 Hemodynamic • Hemo means blood, and dynamics means movement. • Movement of blood throughout the body. • Hemodynamics is the movement of blood through blood vessels. Blood Composition Blood Function 45 % solid components 55 % liquid (Plasma) 1. Transportation of blood gases, nutrients and waste RBC 91.5 % - water 2. Homeostasis (regulation) of pH, temperature and water content WBC 7 % plasma proteins 3. Protection Platelet 1.5 % other solutes
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  JULY 29, 20266  Forces involved in the movement of blood throughout the human circulatory system include: 1. Gravitational force 2. Hydrostatic pressure 3. Kinetic and potential energy provided by the cardiac pump  Properties of blood that affect the flow: 1. Viscosity 2. Volume of blood  Factors affecting movement of blood through vascular channels include: 1. Size of blood vessel 2. Condition of blood vessel 3. Smoothness of lumen 4. Destination of blood
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  JULY 29, 20267 • The total amount of blood flowing through the circulation is called cardiac output (CO). • Flow of blood is usually measured in l/min. Cardiac Output = Stroke Volume x Heart Rate • Cardiac output is influenced by blood pressure and resistance. Cardiac Output
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  JULY 29, 20268 • Blood Pressure - the pressure exerted by blood on the inner wall of blood vessels. • It depends upon the diameter of blood vessels. • Systolic BP- the pressure of the blood as a result of contraction of the ventricles. • Diastolic BP- the pressure when the ventricles are at rest. • Normal Range – 120/80 mmHg (systolic/diastolic) Blood Pressure
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  JULY 29, 202610 Electrophysiology of Heart • Electro means electric, and physiology means function. How does the heart work? • The heart's electrical system produces signals that regulate the timing of heartbeats. • These signals are created by natural electrical impulses that coordinate contractions of the heart's different parts, which keeps blood flowing and creates the heartbeat. • Electrophysiology (EP) is a series of tests that evaluate the heart’s electrical activity. • The study can help diagnose abnormal heart rhythms.
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  JULY 29, 202611  Drugs action on heart can be understood by following properties –  Cardiac action potential • The cardiac action potential, the basic unit of electrical activity in the heart, produces cardiac contraction. • Under the influence of trigger events, potassium, sodium and calcium ions cross the cell membrane, thereby generating ion currents. 1. Impulse generation • Non-automatic fibres • Automatic fibres 2. Conduction 3. Excitability 4. Refractory period
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  JULY 29, 202612 • These are ordinary working myocardial fibres. • They cannot generate an impulse of their own. • During diastole, the resting membrane potential remains stable (-90 mV). • When stimulated, membrane potential is divided into following phases –  Phase 0 (Opening of Na+ channel)  Phase 1 (Opening of K+ channel)  Phase 2 (Opening of Ca++ channel)  Phase 3 (Opening of K+ channel)  Phase 4 (Return to resting membrane potential) 1. Impulse Generation  Nonautomatic fibres • Electrophysiologically, two types of myocardial fibres can be distinguished – a) Non-automatic fibres b) Automatic fibres
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  JULY 29, 202613 Phase 0 (rapid depolarisation) External stimulus to excitable tissue Opens the voltage-gated sodium ion channels Sodium ions enter the cells down their electrochemical gradient Displaces the membrane potential to +30 mV Intracellular movement of sodium ion depolarizes the membrane Increases the membrane conductance to sodium ions
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  JULY 29, 202614 Phase 1 (early repolarization) • Following Phase 0, the membrane repolarizes rapidly and transiently to almost 0 mV because of the inactivation of the sodium ion channel and simultaneous transient increases in outward potassium currents. Phase 2 (Plateau) • Membrane potential remains approximately 0 mV for a relatively prolonged duration. • A balance between slow inward Ca2+ and outward K+ currents mediates the plateau phase of the action potential. Phase 3 (repolarisation) • Inactivation of Ca2+ channels and a simultaneous increase in outward K+ current through K+ channels produce a net outward movement of positive charge and repolarization of the membrane.
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  JULY 29, 202615 • The membrane potential of ventricular fibers remains at the resting membrane potential until the cell is simulated again. Phase 4 (resting membrane potential)
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  JULY 29, 202616 • These are present in the sinoatrial (SA) nodes, atrioventricular (AV) nodes and in the His-Purkinje system. • The types of action potential in the heart can be separated into two categories: (1) Fast-response action potentials, which are found in the His-Purkinje system and atrial or ventricular cardiomyocytes (2) Slow-response action potentials, which are found in the pacemaker cells in the SA and AV nodes  Automatic fibres
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  JULY 29, 202617 2. Conduction • The rate of conduction through a fibre depends on its membrane responsiveness • This relationship is seen in atrial fibres, ventricular fibres and Purkinje fibres • Small cells at the upper margin of the AV node - low conduction velocity (20 mm/sec) • Purkinje fibre – high conduction velocity (4000 mm/sec) 3. Excitability • It is the strength of stimulus required to generate an AP • Hyperpolarization – decreases excitability • Depolarization (starting) – increases excitability • When resting membrane potential is reduced (below -55 mV), the fibre becomes unexcitable
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  JULY 29, 202618 4. Refractory period • Pharmacologically, the effective refractory period (ERP) is the minimum interval between two propagating APs.
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  19  References 1) Essentialsof Medical Pharmacology, 8th Edition by KD Tripathi, Pg no. 320-353 2) Rang and Dale's Pharmacology, 8th Edition by H. P. Rang, J. M. Ritter, R. J. Flower, G. Henderson; Elsevier Churchill Livingstone; Pg no. 425-455 3) Goodman and Gilman's The Pharmacological Basis of Therapeutics, 12th Edition by Laurence L. Brunton and Bjorn C. Knollmann, Pg no. 978-1019 JULY 29, 2026
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  T H AN K Y O U 20 JULY 29, 2026