[Music] welcome to this presentation on inotropes after completion and reflection on this session you should be able to describe the usage and effects of inotropes and outline how inotropes may affect your practice and the patient's cardiac status and care inotropes are agents that influence the contractility of muscle tissue when people refer to inotropes they are usually referring to positive ionotropes which increase the force of contractility however there are also drugs with negative inotropic effects which decrease the force of contractility the agents focused on in this lecture are positive inotropes digoxin is a drug which falls under the category of inotropes it increases the force of velocity and increases the force of myocardial contraction and therefore is called a positive inotrope digoxin also inhibits the sodium pump causing an increase in intracellular calcium decreases conduction in the av node and decreases ventricular response in atrial fibrillation digoxin by increasing the levels of intracellular calcium prolongs the slope of phase iv diastolic depolarization decreasing the heart rate digoxin also has a vasodilator effect reducing afterload indications for the use of digoxin are atrial fibrillation with uncontrolled ventricular response which is a ventricular heart rate of more than 100 beats per minute heart failure due to systolic dysfunction who are new york heart association class 2 3 and 4 failure of diuretics and vasodilator therapy in heart failure and severe heart failure with reduced ef or ejection fraction accompanied by hypotension which limits the use of vasodilators digoxin has multiple drug interactions which either raise the levels of digoxin or enhance its ability to cause bradycardia and should therefore be used in caution with those patients on antiarrhythmics beta blockers clonidine methyldopa certain antibiotics and atorvastatin there are many conditions that increase the sensitivity to digoxin and therefore these patients should be monitored closely for toxicity these conditions include elderly patients over the age of 70 thin patients with low skeletal mass electrolyte imbalances acute mi fibrotoxic heart disease renal failure and chronic obstructive pulmonary disease patients on digoxin are at risk of developing please note that some of the content from the original presentation has been moved around namely the audio that was originally on slide six has been moved to slide anorexia so acute heart failure and use of ionotropes takes place after the questions are digested and sliding such as the audio remains unchanged though so i will not be recording restlessness insomnia drowsiness and weakness arrhythmias such as premature ventricular contractions or pvcs and av block tachycardias such as junctional tachycardia and ventricular tachycardia and brady arrhythmias such as sinus bradycardia sinus arrest and sinoatrial block let's reflect on how digoxin works what makes digoxin useful for treating both heart failure and afib pause the video and take some time to think on this question digoxin acts as a positive inotrope increasing the force of contraction to help increase cardiac output in a failing heart and as a negative chronotrope decreasing the heart rate to control atrial fibrillation with rapid ventricular rate next we will discuss acute heart failure and the use of inotropes there are three clinical conditions of heart failure they include chronic heart failure acute heart failure with pulmonary edema and cardiogenic shock acute heart failure needs acute support to the failing circulation or the condition will worsen cardiogenic shock occurs when there is inadequate cardiac output to maintain blood supply to the circulatory system and tissues a variety of catecholamine-like agents are used for acute heart failure depending on the combination of acute ionotropic stimulation acute vasodilation and acute vasoconstriction that may be required in this slide you will see a chart that reviews the sympathetic nervous system's receptors and their effects in order to understand how inotropes work you will need to fully understand the receptors they block or stimulate along with the location and the desired effect alpha receptors are located in the blood vessels and when stimulated cause vasoconstriction of most vessels beta-1 receptors are mostly in the heart and when stimulated increase contractility and heart rate beta-2 receptors are found in the bronchial and vascular smooth muscle and cause bronchodilation and vasodilation when stimulated dopaminergic receptors are located in the renal and mesenteric arteries and when stimulated cause dilation of renal and mesenteric arteries in this slide you will see a list of inotropic agents and the receptors they stimulate dobutamine is an agent that mostly stimulates beta-1 receptors moderately stimulates beta-2 receptors and has little alpha stimulation this results in increase in contractility of the heart muscle and vasodilation of vascular smooth muscle dopamine is an agent that mostly affects beta 1 and alpha receptors and its effects are dose-dependent epinephrine is an agent that mimics our own adrenaline and stimulates all receptors of the sympathetic nervous system giving a similar response as the fight-or-flight response norepinephrine also mimics our own adrenaline but stimulates mostly alpha and beta-1 receptors sympathomimetic drugs such as the ones discussed in the previous slides are used to augment the sympathetic nervous system or sns actions especially after the patient's endogenous supplies are depleted such as in acute heart failure these agents are also used to maintain blood supply to the circulatory system and tissues by providing adequate cardiac output when the patient is unable to the results are an increase in contractility stroke volume vasoconstriction or vasodilation increase in heart rate blood pressure cardiac output and ultimately increased profusion of the circulatory system and tissues in this table you will see listed the names of the inotropic agent along with the inotropic effect on blood vessels heart rate blood pressure diuresis and rhythmic risk this will be a good tool to study and review let's reflect on the use of inotropes why are inotropes useful in treating cardiogenic shock cardiogenic shock means that the patient is not adequately perfusing their body tissues inotropes treat cardiogenic shock by increasing cardiac output through increased heart rate vasoconstriction and force of contraction this brings us to the end of this slide presentation on inotropes [Music]