Chapter 17 Heart Failure Class Notes PDF

# Chapter 17 Heart Failure ## Heart Failure Basic Concepts - Inability of heart to meet needs - LVEF: left ventricular ejection fraction - Normal: 60%-70% - Heart failure: less than 40% - Should not be confused with cardiac arrest - Epidemic proportions in U.S. - As survivab...

# Chapter 17 Heart Failure ## Heart Failure Basic Concepts - Inability of heart to meet needs - LVEF: left ventricular ejection fraction - Normal: 60%-70% - Heart failure: less than 40% - Should not be confused with cardiac arrest - Epidemic proportions in U.S. - As survivability of cardiac disorders (i.e., MI) has increased, incidence of heart failure has gone up ## Heart Failure Risk Factors - Age - Ethnicity - Family history - Congenital heart defects - Viral myocarditis - Kidney conditions - Diabetes - Obesity - Sleep apnea - Lifestyle - Smoking - Sedentary - Medications - Anabolic steroids - Alcohol abuse ## Cardiac Output - Amount of blood pumped by LV per minute - Cardiac output = HR × SV (stroke volume) - Approximately 5 L/min at rest - Cardiac index = cardiac output/body surface area ## Factor Affecting Heart ### Preload - Amount heart is filled per beat (EDV: end-diastolic volume) - Increased EDV leads to increased SV (to a point) ### Afterload - Resistance that heart pumps against - Increased afterload reduces cardiac output ## Factor Affecting Heart-2 ### Contractility - Force of contraction - Increased preload increases contractility (to a point) - SNS activation increases contractility - High afterload reduces contractility ### Definitions - Inotropic - Force of contraction - Chronotropic - Rate of heart ## Failing Heart ### Pathophysiological Processes Left Ventricular Failure - Activation and cycling of RAAS due to poor renal perfusion - Results in: - Increased resistance against LV - Increased vasoconstriction (angiotensin II) - Increased blood volume (aldosterone) - LV fails, further working against these responses - Adrenergic stimulation - Decreased BP stimulates baroreceptors - Activate SNS - Increased HR and vasoconstriction - Ventricular remodeling - Angiotensin II, TNF-alpha - Progressive weakening of myocardium leading to further failure - Pulmonary edema - Oxygen diffusion is hindered ## Cardiovascular Regulatory Mechanisms - Compensatory mechanisms: detrimental effects over time, as failing heart is overloaded with fluid leading to edema - Natriuretic peptides - Increase urine output (sodium and water excretion) in response to elevated blood volume - ANP: atrial natriuretic peptide - Increases urine output, blocks renin and aldosterone release, decreases vasoconstriction - BNP: brain or B-type natriuretic peptide - Released from ventricles when overstretched - High levels associated with heart failure ## Heart Failure Causes ### Cardiomyopathies - Ischemic - Myocardial fibrosis and scarring of heart - Dilated - Enlargement of ventricles - Restrictive - Can not fill - Hypertrophic - Usually LV muscle enlarged, encroaches on ejection of blood into aorta - Primary: genetic - Secondary: due to HTN - Heart valve abnormalities - Mitral regurgitation (insufficiency) - Valve does not close properly, backward flow into right atrium (decreased blood ejected from LV) - Aortic stenosis - LV must generate more pressure to eject blood - LVH develops - Dysrhythmias - Irregular heart rhythm may precipitate failure - Both tachyarrhythmias and bradyarrhythmias - Cardiac infection - Endocarditis, myocarditis - Pulmonary embolism - Acute RV failure due to increased pulmonary artery pressure - Cor pulmonale - Right-side heart failure due to pulmonary issues - COPD-hypoxia-pulmonary vasoconstriction-increased workload on R-side of heart ## LVF Forward Effects - Forward effects - Decrease perfusion, activate SNS & RAAS - Cerebral symptoms - Confusion, memory loss, anxiety - Constitutional symptoms - Decrease blood flow to GI tract - Muscle weakness - Poor urinary output - Cold and pale extremities ## LVF Backward Effects - Backward effects - Hydrostatic pressure backup into pulmonary circulation - Crackles - Orthopnea - Difficulty breathing while lying down - Classified based on number of pillows patient needs to elevate head to breathe comfortably - Paroxysmal nocturnal dyspnea (PND) - Fluid accumulates in lungs while supine - Patient may report night terrors that awaken - Right Ventricular Failure - Backward effects most significant - JVD: jugular vein distention - Increased central venous pressure (CVP) - Hepatomegaly, splenomegaly, ascites - Hepatojugular reflex may be present - Venous congestion of GI tract causing anorexia, nausea - Peripheral edema - Right Ventricular Failure (RVF) - Biventricular Failure - Dysfunction in 1 heart chamber affects other chambers - Patients most often present with failure of both sides of heart - Signs and symptoms of both right- and left-side failure are normally present ## Heart Failure: Laboratory and Diagnostic Studies - Echocardiogram - Estimate LVEF, size of heart chambers, valve disorders - Elevated B-type natriuretic peptide - Diluted electrolytes due to fluid retention - Chest x-ray - Cardiomegaly - Vascular congestion in pulmonary fields - ECG - No specific sign ## Heart Failure Treatment ### Medications - ACE inhibitors - Block angiotensin-converting enzyme - Cornerstone of heart failure treatment - Angiotensin II receptor blockers (ARB’s) - Often used in those who can't tolerate ACE inhibitors - Beta 1-adrenergic blockers - Slow HR, lessen vasoconstriction - Also Alpha and Beta blocker - Diuretics - Reduce fluid volume (loop diuretic: can lead to hypokalemia) - Aldosterone antagonist (potassium sparing) - Underlined medications block the body's neurohormonal response - Positive inotropic and negative chronotropic agents - Digitalis - Neprilysin inhibitors - Neprilysin breaks down B-NP and ANP - Neprilysin inhibitors reduce this breakdown - Neprilysin also prevents breakdown of angiotensin II, thus often prescribed with ARB's - Nitrates - Arterial and venous vasodilators - Reduce heart's workload - Coronary artery dilation - Arterial vasodilators - Reduce afterload - May be used with nitrates (isosorbide dinitrate/hydralazine) - Lifestyle modifications - Exercise, low sodium diet, smoking cessation - Can benefit from cardiac rehab