Untitled Quiz

Heart Failure (HF)

• Inability of ventricles to pump sufficient blood for body's needs
• Heart muscle weakens due to aging or diseases

Diseases Associated with Heart Failure

• Coronary artery disease (CAD)
• Mitral stenosis
• Myocardial infarction (MI)
• Chronic High Blood Pressure (HTN)
• Diabetes mellitus
• No cure, only prevention and slowing of progression is possible

Left-Sided Heart Failure

• Blood accumulates in left ventricle
• Left ventricle thickens and enlarges (hypertrophy)
• Cardiac remodeling occurs
• Blood backs up into lungs
• Cough and shortness of breath result

Right-Sided Heart Failure

• Blood backs up into veins
• Causes peripheral edema and organ engorgement
• Less common than left-sided HF

Pathophysiology of Heart Failure

• Failing heart leads to decreased cardiac output
• Diminished renal blood flow
• Increased sympathetic activity leads to increased heart rate & force of contraction
• Vasoconstriction increases blood pressure
• Retention of sodium and water leads to increased plasma volume
• Increased afterload
• Increased cardiac workload
• Myocardial dysfunction worsens heart failure
• Pulmonary and peripheral edema occurs

Preload

• Affects cardiac output
• Degree myocardial fibers stretched before contraction
• Frank-Starling law: more stretched, more forceful contraction
• Positive inotropic agents increase preload to increase contractility

Afterload

• Affects cardiac output
• Pressure in aorta, must be overcome to eject blood from left ventricle
• Lowering blood pressure decreases afterload, decreasing workload of the heart

Pharmacologic Management of Heart Failure

• Slowing heart rate
• Increasing contractility
• Reducing myocardial workload

Drugs for Heart Failure

• Treat symptoms: slow heart rate, increase contractility, reduce workload

Stages for Treating Heart Failure

• Stage A: High risk for developing HF, no structural heart disease or symptoms, lifestyle modifications, treat comorbid conditions.
• Stage B: Structural evidence of heart disease (eg. previous MI), no symptoms, continue lifestyle changes, treat with ACE inhibitor or ARB; beta blockers can be added if prior or current symptoms
• Stage C: Structural heart disease with symptoms, continue lifestyle/meds from stage B, consider beta blockers, other measures like digoxin, isosorbide dinitrate with hydralazine, or aldosterone antagonist to control symptoms
• Stage D: Symptoms at rest or with minimal exertion, despite optimal medical therapy, lifestyle modifications/treatment as in stage C, or consider intravenous (IV) vasodilators or other medications like ivabradine, diuretics, dopamine, dobutamine and more intensive measures

ACE Inhibitors

• Reduce afterload
• Drugs of choice for heart failure
• Enhance excretion of sodium and water
• Lower peripheral resistance, reduce blood volume
• Increase cardiac output
• Prototype drug: lisinopril (Prinivil, Zestril)
• Mechanism: inhibit ACE enzyme and decrease aldosterone secretion
• Primary use: to decrease blood pressure, reduce blood volume; dilate veins
• Adverse effects: first-dose hypotension, cough, hyperkalemia, renal failure

Angiotensin II Receptor Blockers (ARBs)

• Actions very similar to ACE inhibitors
• Often used for patients intolerant of ACE inhibitors

Diuretics

• Increase urine flow
• Reduce blood volume and cardiac workload
• Reduce edema and pulmonary congestion
• Prescribed in combination with other drugs

Cardiac Glycosides

• Increase force of heartbeat, slow heart rate
• Improve cardiac output
• Second-line treatment for HF
• Narrow therapeutic range
• Prototype drug: digoxin (Lanoxin)
• Mechanism: to cause more forceful heartbeat, slower heart rate
• Primary use: to increase contractility or strength of myocardial contraction
• Adverse effects: neutropenia, dysrhythmias, digitalis toxicity

Beta-Adrenergic Blockers

• Slow heart rate and reduce blood pressure
• Inotropic effects
• Reduce workload of heart
• Prototype drug: metoprolol (Lopressor, Toprol XL)
• Mechanism: Block cardiac action of the sympathetic nervous system to slow heart rate, blood pressure, reducing workload of heart
• Primary use: reduce symptoms of heart failure, slow progression of disease
• Adverse effects: fluid retention, worsening of heart failure, fatigue, hypotension, bradycardia, heart block

Direct Vasodilators

• Minor role in HF treatment
• Lower blood pressure
• Relax blood vessels

Phosphodiesterase Inhibitors

• Block enzyme phosphodiesterase
• Increase calcium for myocardial contraction
• Cause positive inotropic response and vasodilation
• Increase contractility and decrease afterload
• Short-term therapy only
• Prototype drug: milrinone (Primacor)
• Mechanism: to block enzyme phosphodiesterase in cardiac and smooth muscle, increasing myocardial contraction force and cardiac output
• Primary use: as short-term therapy for heart failure
• Adverse effects: hypokalemia, hypotension, ventricular dysrhythmias

Patient Teaching

• Therapeutic response (weeks/months)
• Sodium and potassium restrictions
• Avoid use with other medications/herbals/vitamins
• Monitor sodium intake
• Report weight loss, fatigue, muscle cramps
• Change positions slowly
• Monitor blood pressure/pulse, report pulse below 50
• Report signs of worsening heart failure
• Do not stop medication abruptly
• Monitor therapeutic levels with laboratory tests
• Know signs/symptoms of toxicity
• Monitor pulse rate, report weight gain
• Eat foods high in potassium
• Report irregular/rapid heart rate
• Report fever of 101°F or higher, chest pain
• Report pain/swelling at IV infusion site