The Heart Anatomy and Function

The Heart

• The heart is a pumping organ, responsible for pumping blood throughout the body.
• Heart failure is a condition where the heart's ability to pump blood effectively is compromised.
• Heart failure affects the pumping chambers, called ventricles.
• The heart has four chambers (two atria and two ventricles).
• The heart has valves; tricuspid, bicuspid and semilunar that control blood flow.
• Images of the heart (CT scans/X-rays etc), can help visualize heart conditions
• Cardiac output measures total blood volume pumped by the heart each minute, calculated as stroke volume multiplied by heart rate.
• Stroke volume is the amount of blood ejected by the left ventricle each heartbeat.
• Heart rate is the number of heartbeats per minute.
• Factors that affect stroke volume: preload (volume of blood at the end of diastole), afterload (resistance against pumping), and contractility (strength of contraction).
• There are three types of angina pectoris: classic/stable, unstable, and variant/Prinzmetal/vasospastic.
• Angina pectoris is characterized by chest pain caused by reduced blood flow to the myocardium.
• Symptoms of angina often include tightness, pressure in the center of the chest, and pain radiating to the left arm, neck, and jaw.

Regulation of Heart Function

• Cardiac output is the total volume of blood pumped by the heart per minute.
• Stroke volume is the amount of blood ejected from the left ventricle per heartbeat.
• Heart rate is the number of heartbeats per minute.
• Cardiac output = Stroke volume × Heart rate

Antihypertensive Agents

• Hypertension is a condition in which blood pressure is persistently elevated.
• Hypertension is categorized in four stages; Normal (low blood pressure), Elevated (slightly elevated blood pressure), High blood pressure (hypertension) Stage 1, High blood pressure (hypertension) Stage 2, Hypertensive crisis.
• Hypertension stages are defined by systolic and diastolic blood pressure levels.
• Antihypertensive agents include diuretics, sympatholytic drugs, alpha 2 agonists, alpha adrenergic blockers, peripherally acting sympatholytics, alpha 1 & beta 1 blockers, and direct-acting arteriolar vasodilators.
• Treatment for hypertension depends on the stage and cause.
• Non-pharmacological hypertension management includes stress reduction techniques, exercises, salt restriction, decreasing alcohol ingestion, quitting smoking, and weight reduction .
• Diuretics promote sodium depletion, which reduces extracellular fluid volume.
• Sympatholytic drugs (e.g., beta-blockers) reduce cardiac output and sympathetic tone
• Alpha 2 agonists decrease sympathetic response, reducing BP.
• Alpha adrenergic blockers cause vasodilation, and maintaining renal blood flow.
• Peripherally acting sympatholytics block norepinephrine release.
• Alpha 1 and beta 1 blockers block both alpha and beta receptors.
• Direct-acting arteriolar vasodilators relax blood vessels, increasing blood flow and reducing BP.
• ACE inhibitors and angiotensin II receptor blockers (ARBs) target the renin-angiotensin-aldosterone system.

Heart Failure

• Heart failure occurs when the heart cannot effectively pump blood to meet the body's needs.
• Congestive heart failure can be left-sided or right-sided depending on the affected ventricle/ventricles
• Left-sided CHF involves weakened left ventricle, and symptoms may include dyspnea, orthopnea, fatigue, restlessness, crackles, peripheral cyanosis, dry cough, and frothy blood tinged mucus.
• Right-sided CHF involves weakened right ventricle where blood accumulates in the peripheral tissue and symptoms may include Abdominal pain, fatigue, bloating, nausea, dependent pitting edema, ankle edema, ascites, jaundice, hepatomegaly, decreased urine output, increased CVP, and HPN.
• Stages of heart failure are categorized based on severity (A, B, C, D).
• Agents used in treating heart failure include cardiac glycosides (e.g., digoxin), diuretics, and other agents.

Antiarrhythmic Agents

• Cardiac dysrhythmia is any deviation from the normal rate or pattern of the heartbeat.
• Various classes of antiarrhythmic drugs, based on their mechanism of action, have varying effects on cardiac electrical activity.
• Class 1 Antiarrhythmics: block sodium channels, affecting how quickly electrical impulses move through the heart, classically used in atrial and ventricular arrhythmia.
• Class 2 Antiarrhythmics: beta-blockers, which reduce excitability in the heart, thus decreasing heart rate and cardiac workload.
• Class 3 Antiarrhythmics: prolongs repolarization. used in ventricular arrhythmias.
• Class 4 Antiarrhythmics: calcium channel blockers, reduce the excitability of cardiac cells, and usually affect the heart rate.

Nursing Responsibilities

• Numerous responsibilities for nurses caring for patients with heart conditions.
• Monitor vital signs, including heart rate and blood pressure.
• Administer medications correctly, following proper protocols and guidelines, such as monitoring for 2-3 minutes.
• Educate patients about medication dosages, side effects, and necessary lifestyle changes.
• Conduct patient assessments to identify potential complications and necessary interventions.