Decrease Cardiac Output (1) - Decrease Cardiac Output Nursing Implications Definitions Heart Failure Heart is unable to pump an adequate supply of blood

Decrease Cardiac Output (1) - Decrease Cardiac Output...

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Decrease Cardiac OutputNursing Implications
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DefinitionsHeart Failure: Heart is unable to pump an adequate supply of blood to meet the body’s demandHeart Failure also called cardiac decompensationcardiac insufficiencycardiac incompetenceIf fluid retention occurs with heart failure, it is called congestive heart failure
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Anatomy & Physiology
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Anatomy & PhysiologyHeart rateis the number of times the heart beats in one minute. The average adult resting heart rate is 75 beats per minute (bpm).Stroke volumeis the amount of blood pumped by each ventricle with each heartbeat. The average adult resting stroke volume is 70 ml per beat.Cardiac outputis the amount of blood pumped out by each ventricle in one minute. It is directly related to heart rate and stroke volume:
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Anatomy & PhysiologyToo rapid a heart rate can decrease cardiac output;There is too little time for ventricles to fill properly.
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Anatomy & PhysiologyPreload: ventricular blood volume at end of diastole; initially increases cardiac output via Starling’s law (increase force of contraction); with too much preload ventricle cannot efficiently empty—decreased ejection fraction
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Anatomy & Physiology
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Anatomy & PhysiologyAfterload: ventricular blood volume at end of systole; blood that did not exit heart; increased afterload means decreased ejection fraction (norm 60-80%)Increasing the resistance to blood exiting the heart, will increase the work of the heart and afterloadIncreased blood pressure and peripheral resistance,And stenosis( narrowing) of pulmonic and aortic valveincreases resistance to blood exiting heart.
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Anatomy & Physiology
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Anatomy & PhysiologyChronic Heart Failure:gradually occurs as body compensatesadaptations are milderAcute heart failure: rapidly occurring usually related to MIAdaptations: syncope, cardiogenic shock, cardiac arrest, death
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Anatomy & PhysiologyHow heart compensate in heart failure:1. Increased sympathetic tone:increases heart rateincreases contractility of heartincreases peripheral vascular constrictionreturns blood to heart increases preload2. Hypertrophy of heart muscle3. Starling’s Law: increased ventricle filling during diastole (end-diastolic volume/preload) increases the volume ejected during the resulting systolic contraction (stroke volume)
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Which measure would decrease afterload?1.Raising the blood pressure2.Increasing the heart rate3.Repairing aortic stenosis4. Stimulating peripheral resistance
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Heart Failure: EpidemiologyMen more than womenIncreased with COPD (smokers)Increased with age but can be seen in newborns with congenital defectsContributes directly or indirectly to about 260,000 deaths annually
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Heart Failure: Risk FactorsCAD & MICardiomyopathy (alcohol, infectious)Cardiac TamponadeValvular disease (stenosis, insufficiency)Congenital defectsDysrhythmiasFluid overload (renal or liver disease)Electrolyte disturbances (sodium important)Endocrine disturbancesAnemiaIncreased metabolic needs
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