Cardiac: CHF, Dysrhythmias, and Pharmacology

Preload

The force filling and stretching the ventricles during diastole.

Afterload

The left ventricular pressure required to force blood into systemic circulation.

Contractility

The force and efficiency of myocardial squeezing during contraction.

Stroke Volume (SV)

The volume of blood ejected from the left ventricle per heartbeat.

Ejection Fraction (EF)

The percentage of end-diastolic blood volume pumped out during each contraction.

Cardiac Output (CO)

The volume of blood ejected by the left ventricle in one minute.

Cardiac Cycle

The complete event from the beginning of one heartbeat to the next.

Diastole vs. Systole

Diastole is ventricular relaxation/filling; Systole is ventricular contraction/ejection.

Endocarditis

Valvular infection/inflammation typically caused by Rheumatic fever or group A strep.

Pericarditis

Inflammation of the pericardial sac surrounding the heart.

Pericardial Effusion

Inflammation causing fluid buildup inside the pericardial sac.

Myocarditis

Inflammation of the myocardium that can lead to cardiomyopathies.

Dilated Cardiomyopathy

Enlargement and dilation of the left ventricle, often congenital.

Hypertrophic Cardiomyopathy

Thickened interventricular septum causing decreased left ventricular capacity.

Restrictive Cardiomyopathy

Rigid, damaged heart wall restriction usually occurring post-myocardial infarction.

Atrioventricular (AV) Valves

Tricuspid and Mitral (bicuspid) valves separating atria from ventricles.

Semilunar Valves

Pulmonary and Aortic valves regulating blood exit from the heart.

Stenosis vs. Regurgitation

Stenosis prevents full opening (impedes outflow); Regurgitation prevents full closing (causes backflow).

Left-Sided Heart Failure Causes

CAD, MI, hypertension, diabetes, obesity, and damaged or stiff myocardium.

Right-Sided Heart Failure Causes

Left-sided heart failure and pulmonary hypertension.

Right vs. Left Heart Failure Manifestations

Right HF causes systemic/peripheral edema; Left HF causes pulmonary congestion/edema.

Nonpharmacological Treatment for HF

Sodium restriction, fluid/fat management, smoking cessation, and moderate exercise.

Echocardiogram in Heart Failure

Ultrasound visualizing heart structures to measure stroke volume, CO, and EF.

B-Type Natriuretic Peptide (BNP)

Blood marker used to differentiate cardiac heart failure from pulmonary dyspnea.

Goals of Heart Failure Pharmacotherapy

Increase contractility, decrease afterload, and reduce circulating fluid volume.

Automaticity and Rhythmicity

The ability of cardiac cells to initiate impulses spontaneously and regularly.

Depolarization vs. Repolarization

Depolarization is electrical activation via Na+/K+ shift; Repolarization is electrical recovery.

Absolute Refractory Period

Phase during which myocardial cells cannot respond to any new stimulus.

Relative Refractory Period

Phase where myocardial cells can depolarize only in response to abnormally strong stimuli.

Angiotensin Receptor Neprilysin Inhibitors (ARNIs)

Sacubitril/Valsartan (Entresto); promotes diuresis, vasodilation, and RAAS inhibition.

ARNI Nursing Considerations

Do not combine with ACEIs/ARBs; monitor renal function, potassium, and bleeding risks with NSAIDs.

Cardiac Glycosides (Digoxin)

Positive inotrope that increases contractility while slowing heart rate.

Digoxin Toxicity Symptoms

Bradycardia, dysrhythmias, hyperkalemia, and visual disturbances like yellow halos.

ACE Inhibitors Action & Examples

Captopril, Lisinopril, Enalapril; cause vasodilation and reduce afterload.

ACE Inhibitor Adverse Effects

Persistent dry cough, angioedema, and hyperkalemia.

Angiotensin II Receptor Blockers (ARBs)

Losartan, Irbesartan; cause vasodilation to treat hypertension and heart failure.

Priority Assessments for Diuretic Therapy

Monitor cardiac status, potassium levels, and signs of fluid volume deficit.

P Wave on EKG

Represents atrial depolarization, which triggers atrial contraction.

QRS Complex on EKG

Represents ventricular depolarization, which triggers ventricular contraction.

T Wave on EKG

Represents ventricular repolarization (electrical recovery period).

Class I Antidysrhythmics

Sodium channel blockers (e.g., Quinidine, Lidocaine, Propafenone, Flecainide).

Class II Antidysrhythmics

Beta-adrenergic blockers (e.g., Propranolol, Esmolol, Acebutolol).

Class III Antidysrhythmics

Potassium channel blockers (e.g., Amiodarone, Sotalol, Ibutilide).

Class IV Antidysrhythmics

Calcium channel blockers (e.g., Verapamil, Diltiazem, Adenosine).

Atropine Action & Indications

Anticholinergic agent used to increase heart rate during severe bradycardia.

Atropine Nursing Interventions

Monitor heart rate response and assess for urinary retention.

Dietary Recommendations for Heart Failure

Low sodium, reduced saturated fats, high fiber, lean proteins, and fluid monitoring.