Understanding Heart Failure

• Approximately 5,000 Canadians die annually from heart failure.
• The 5-year survival rate for individuals diagnosed with heart failure is 50%.
• Prevention is critical in managing heart failure.

Left Sided Heart Failure

• Associated with pulmonary edema, coughing, shortness of breath and dyspnea

Right Sided Heart Failure

• Manifests as systemic venous congestion, pedal edema, jugular vein distention, ascites, and hepatic congestion.

Causes of Heart Failure

• Myocardial deficiency due to inadequate contractility, myocardial infarction, coronary artery disease, cardiomyopathy, and valvular insufficiency.
• Inadequate filling caused by atrial fibrillation, infection, tamponade, and ischemia.
• Increased workload from pressure overload, pulmonary hypertension, systemic hypertension, and outflow obstruction.
• Volume overload is due to hypervolemia, congenital abnormalities, anemia, thyroid disease, infection, and diabetes.

New York Association’s Classification of Heart Failure

• Class I: No limitations in physical activity.
• Class II: Ordinary physical activity leads to fatigue, dyspnea, or other symptoms.
• Class III: Marked limitation in physical activity.
• Class IV: Symptoms occur at rest or with any physical activity.

Drug Therapy for Heart Failure

• Positive inotropic drugs increase myocardial contraction force.
• Positive chronotropic drugs increase the heart rate.
• Positive dromotropic drugs accelerate cardiac conduction.
• Phosphodiesterase inhibitors, cardiac glycosides, and B-type natriuretic peptides are used.
• Other drugs include angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, ß-Blockers, and diuretics.

Early Treatment of Heart Failure

• Includes angiotensin-converting enzyme inhibitors (e.g., lisinopril, enalapril maleate, captopril).
• Angiotensin II receptor blockers (e.g., valsartan).
• Certain ß-blockers (e.g., bisoprolol, extended-release metoprolol tartrate, carvedilol).
• Loop diuretics (e.g., furosemide) are used to reduce symptoms of heart failure caused by fluid overload.
• Aldosterone inhibitors (e.g., spironolactone, eplerenone) are added as heart failure progresses.
• Digoxin is added only after these drugs are used.
• Dobutamine is a positive inotropic drug.
• Hydralazine/isosorbide dinitrate use is recommended specifically for Black patients.

Angiotensin-Converting Enzyme Inhibitors

• Prevent sodium and water resorption by inhibiting aldosterone secretion.
• Diuresis results, decreasing preload and the heart's workload.
• Examples: lisinopril, enalapril maleate, fosinopril sodium, quinapril hydrochloride, captopril, ramipril, trandolapril, and perindopril erbumine.

Lisinopril (Prinivil®, Zestril®)

• Used for hypertension, heart failure, and acute myocardial infarction.
• Can cause hyperkalemia, dry cough, and decreased renal function.

Angiotensin II Receptor Blockers

• Potent vasodilators that decrease systemic vascular resistance (afterload).
• Used alone or in combination with diuretics to treat hypertension or heart failure.
• Examples: valsartan (Diovan®), candesartan cilexetil, eprosartan mesylate, irbesartan, telmisartan, olmesartan medoximil, and losartan potassium.

Valsartan (Diovan®)

• Carries similar adverse effects as lisinopril.
• Less likely to cause cough or hyperkalemia compared to angiotensin-converting enzyme inhibitors.

β-Blockers

• Act as cardioprotective agents by preventing catecholamine-mediated actions on the heart.
• Reduce or block sympathetic nervous system stimulation to the heart and its conduction system.
• Examples: metoprolol and carvedilol.

Aldosterone Antagonists

• Examples: spironolactone and eplerenone.
• Useful in severe heart failure stages.
• Block the renin-angiotensin-aldosterone system, which causes increased aldosterone levels, leading to sodium and water retention, worsening heart failure.

Spironolactone (Aldactone®)

• Potassium-sparing diuretic and aldosterone antagonist that reduces heart failure symptoms.

Eplerenone (Inspra®)

• Selective aldosterone blocker that blocks aldosterone at its receptors in the kidney, heart, blood vessels, and brain.

Hydralazine/Isosorbide Dinitrate

• Approved specifically for use in Black patients.

Dobutamine Hydrochloride

• β1-selective vasoactive adrenergic drug structurally similar to dopamine.

Phosphodiesterase Inhibitors

• Inhibit the enzyme phosphodiesterase.
• Increase intracellular cyclic adenosine monophosphate, leading to a positive inotropic response, vasodilation, and increased calcium for myocardial muscle contraction.
• Act as inodilators (inotropics and dilators).

Phosphodiesterase Inhibitors: Indications

• Milrinone is the only drug in this category available in Canada.
• Used for short-term management of heart failure in critical care patients.
• Long-term infusions of milrinone are not advised.

Milrinone

• Only available phosphodiesterase inhibitor.
• Available in injectable form only.
• Adverse effects include cardiac dysrhythmias, hypotension, angina, hypokalemia, tremor, and thrombocytopenia.
• Interacts with diuretics (additive hypotensive effects) and digoxin (additive inotropic effects).
• Furosemide must not be injected into intravenous lines with milrinone.

Cardiac Glycosides

• No longer used as first-line treatment and have not been shown to reduce mortality.
• Originally obtained from the Digitalis plant (foxglove).
• Digoxin is the prototype.
• Used in heart failure and to control ventricular response to atrial fibrillation.

Cardiac Glycosides: Mechanism of Action

• Increase myocardial contractility.
• Change electrical conduction properties of the heart.
• Decrease the rate of electrical conduction.
• Prolong the refractory period.

Cardiac Glycosides: Drug Effects

• Positive inotropic effect: Increased force and velocity of myocardial contraction without increased oxygen consumption.
• Negative chronotropic effect: Reduced heart rate.
• Negative dromotropic effect: Decreased automaticity at the sinoatrial node and decreased atrioventricular nodal conduction.
• Increased stroke volume.
• Reduction in heart size during diastole.
• Decrease in venous blood pressure and vein engorgement.
• Increase in coronary circulation.
• Decrease in exertional and paroxysmal nocturnal dyspnea, cough, and cyanosis.
• Promotion of tissue perfusion and diuresis.
• Improved symptom control, quality of life, and exercise tolerance.

Digoxin (Lanoxin®)

• Has a very narrow therapeutic window (0.8 to 2 ng/mL).
• Drug levels and electrolyte levels must be monitored.
• Low potassium levels can increase its toxicity.
• Adverse cardiovascular effects: dysrhythmias, including bradycardia or tachycardia.
• Central nervous system effects: headaches, fatigue, malaise, confusion, convulsions.
• Eye-related adverse effects: coloured vision (seeing green, yellow, purple), halo vision.
• Gastrointestinal adverse effects: anorexia, nausea, vomiting, diarrhea.

Digoxin Toxicity

• Can be treated with digoxin immune Fab therapy.
• Indications for digoxin immune Fab therapy include hyperkalemia (serum potassium > 5 mmol/L) in a digitalis-toxic patient.
• Administer for life-threatening cardiac dysrhythmias and digoxin overdose.

Conditions That Predispose to Digoxin Toxicity

• Hypokalemia, use of cardiac pacemaker, atrioventricular block, hypercalcemia and dysrhythmias
• Hypothyroid, respiratory, or renal disease, advanced age & ventricular fibrillation

Heart Failure Drugs: Nursing Implications

• Assess history, drug allergies, and contraindications.
• Assess clinical parameters including blood pressure, radial/apical pulse for 1 full minute, heart sounds, and breath sounds.
• Assess clinical parameters including weight, input/output measures, electrocardiogram and serum labs like; potassium, sodium, magnesium, calcium, renal, and liver function studies.
• Before giving any dose, count apical pulse for 1 full minute. If less than 60 or greater than 100 beats/min, hold the dose and notify the prescriber.
• Always hold dose and notify prescriber if the patient experiences signs or symptoms of toxicity. -Signs of toxicity include anorexia, nausea, vomiting, diarrhea -Visual disturbances such as blurred vision, seeing green or yellow halos around objects
• Check dosage forms carefully and follow administering instructions.
• Avoid giving digoxin with high-fibre foods, as fibre binds with digitalis.
• Patients should immediately report a weight gain of 1 kg or more in 24 hours or 2 kg or more in 1 week.
• For milrinone, use an infusion pump.Monitor input and output, heart rate and rhythm, blood pressure, daily weights, and respirations.
• Monitor for therapeutic effects such as increased urinary output and decreased edema, shortness of breath/dyspnea, crackles, and fatigue.
• Resolution of paroxysmal nocturnal dyspnea.
• Improved peripheral pulses, skin colour, and temperature.
• Monitor for adverse effects.