Cardiomyopathy (CMP)

Learning Objectives

• Identify structural abnormalities in the three primary cardiomyopathies (CMPs): Dilated, Hypertrophic, Restrictive.

• Recognize risk factors for developing CMPs.

• Distinguish Takotsubo CMP from other dilated CMPs.

• Correlate specific assessment findings related to CMP: Dilated, hypertrophic, restrictive.

• Understand diagnostic tests important for CMP.

• Recall medication therapies used in CMP.

• Plan nursing care for patients with CMP.

Cardiac Structure and Physiology

• Outer Protective Layer: Pericardium (outermost layer that protects heart and provides structure)

• Muscular Middle Layer: Myocardium (cardiac nerves here)

• Thin Inner Layer: Endocardium (innermost layer)

Classification of Cardiomyopathy (CMP)

• Disruption of myocardial structure and function = CMP.

  • Leads to less cardiac output and less oxygen to body.

• Types of Classification:

  • Primary CMP: Idiopathic in nature (no known cause).

  • Secondary CMP: Related to another disease processes.

• Three Major Types: “Dr. H” →

  • Dilated CMP (most common)

    • Subtype: Takotsubo CMP “Broken Heart Syndrome” (often triggered by stress).

    • Left ventricle thinned and stretched out (holds more cardiac output due to weakened muscle).

  • Hypertrophic CMP

    • Left ventricle thickened (holds less cardiac output)

  • Restrictive CMP

    • Decrease in movement of ventricle itself.

Differences in Heart Structure

• Dilated CMP vs Hypertrophic CMP vs Restrictive CMP:

  • Dilated CMP: Left ventricular dilation, thin walls.

    • Weakened contractility/force from stretched ventricle chambers and fluid backup occurs as cardiac output decreases & valves don’t full close.

  • Hypertrophic CMP: Excessive wall thickening, specifically in the septum, leading to stretched cardiac muscle.

    • Heart muscle thickens and makes it harder for heart to pump blood; can’t take in or pump out enough blood.

  • Restrictive CMP: Stiffening of the heart muscle.

    • Restricts the heart's ability to fill, causes decreased cardiac output and increased pressures in the heart chambers.

  • When the body isn’t getting enough oxygen due to the decreased CO, it thinks we have low BP and activates our SNS and stimulates our kidneys to initiate the RAAS system (retains fluid + sodium, excretes potassium) to increase BP.

    • Heart begins to fail after a period of time using these compensatory mechanisms.

Dilated Cardiomyopathy “Balloon”

• Most Common Type of CMP:

  • Often primary (cardiac origin).

  • Causes:

    • Hypertension (HTN)

    • Coronary Artery Disease (CAD)

    • Valvular Heart Disease

    • Cardiotoxins (e.g., alcohol, cocaine)

    • Genetic factors

    • Pregnancy

    • Acute Viral Illness

    • Stress (Takotsubo CMP)

• Pathophysiology:

  • Diffuse inflammation leading to rapid degeneration of ventricle.

  • Characterized by ventricular dilation with thin walls (no hypertrophy).

  • Risk of dysrhythmias → lead to sudden cardiac death (SCD) due to abnormal heart structure conduction and RAAS excreting potassium (hypokalemia)

Takotsubo Cardiomyopathy “Broken Heart Syndrome” </3

• Acute and stress-related condition. Affects left ventricle.

• Most prevalent in postmenopausal women.

• Symptoms resemble those of acute coronary syndrome (heart attack)

  • Cardiac markers (troponin) will be negative → use transthoracic echocardiogram to look.

• Condition is transient = typically resolves within two months.

Clinical Manifestations of Dilated CMP

• Signs & Symptoms:

  • Fatigue

  • Shortness of breath (SOB) at rest

  • Paroxysmal nocturnal dyspnea (wake up SOB from sudden drop) & orthopnea (needing extra pillows to sleep elevated)

  • Dry cough (bronchoconstriction) and palpitations

  • Abdominal bloating, nausea/vomiting, anorexia

• Assessment Findings:

  • S3 and/or S4 heart sounds → extra click sound

  • Heart murmurs → “Whoosh sound”

  • Dysrhythmias

  • Pulmonary edema (e.g., crackles, rhonchi) from leakage into alveoli from back-up due to weakened contractility.

  • Bilateral limb edema (left ventricle not working, backs up into right ventricle, backs into body), hepatomegaly (fluid overload in liver/enlarged liver) → Systolic HF

  • Weak pulses, Jugular Vein Distention (JVD)

• Diagnostic Tools:

  • Echocardiogram (ECHO): Gold standard.**

    • Determines normal dilated CMP vs. Takatsubo

    • Generally present with a lower ejection fraction.

      • 55-65%usually normal

      • <40% BAD → Low ejection fraction in dilated CMP.

  • Chest X-ray (CXR): Cardiomegaly (enlarged heart) and pleural effusion (fluid buildup in the pleural space).

  • ECG: Identifying dysrhythmias, conduction abnormalities (e.g., Bundle Branch Block).

  • Laboratory tests: Elevated BNP (brain natriuretic peptide) levels → released from the ventricle when there’s excess stretch (fluid overload in ventricle).

    • BNP over 100 = bad

  • Heart Cath: Evaluates CAD; may perform endomyocardial biopsy.

Nursing Care for Dilated CMP

• Goal: Increase CO

• Medications (be able to differentiate):**

  • Decrease preload with nitrates and diuretics (amount of blood received by the heart before contraction = heart stretches to fill with blood AKA diastole).

    • Nitrates vasodilate so less blood goes back to heart from veins.

    • Diuretics decrease blood volume going to the heart.

  • Decrease afterload (pressure it takes to squeeze blood out to the body/contraction AKA systole) using ACE inhibitors (vasodilation)→ “chill pril”, beta-blockers (lower HR), and aldosterone antagonists.

    • Decreased afterload = less resistance = heart can pump easier.

  • Antidysrhythmic (treatment if dysrhythmic is caused by CMP or as preventative)

  • Anticoagulants (prevents blood clots by inhibiting the coagulation cascade → Coumadin, LMW heparin).

    • Prevents blood from clotting by inhibiting the coagulation cascade which is a series of steps that leads to the formation of fibrin (protein that forms blood clots).

  • Treat underlying causes: CAD/HTN.

• Nutrition Therapy:

  • Low sodium diet (<2g/day).

  • Fluid restriction (<2L/day).

• Complex Therapies:

  • Ventricular Assist Device (VAD): Temporary or destination therapy.

    • When ventricles contract, the machine pushes onto ventricle to increase cardiac output (amount of blood pumped out per minute).

    • Must have extra batteries at all times → don’t let it die.

    • May be in place until they can get a heart transplant.

  • Automatic Implantable Cardioverter Defibrillator (AICD) with cardiac resynchronization therapy.

    • Recognizes abnormal rhythms and shocks the patient.

  • Heart transplant as a last resort.

Hypertrophic Cardiomyopathy

• Overview:

  • Less common than dilated CMP. Extremely deadly.

  • Pathophysiology:

    • Characterized by massive ventricular hypertrophy without dilation.

    • Results in thick muscles and rapid, forceful contractions.

    • Often leads to stiff ventricles causing impaired relaxation (diastolic heart failure).

      • Can cause aortic outflow obstruction.

      • Diastolic HF is when the heart has difficulty relaxing and filling with blood properly (unable to get enough volume to meet demands of body).

• Causes:

  • Genetic (autosomal dominant).

    • Cardiac death in young athletes.

  • Aortic Stenosis (AS).

    • Aortic valve obstruction

    • Causes heart to pump against higher pressure.

  • Hypertension (HTN).

  • More prevalent in men than women.

• Clinical Manifestations:

  • Some patients may be asymptomatic until too late → SCD during activity.

  • Common Symptoms:

    • Exertional dyspnea → As they need more oxygen, they become symptomatic (SOB).

    • Fatigue

    • Angina

    • Syncope due to aortic outflow obstruction → inability to get blood flow to brain.

• Assessment Findings:

  • Increased apical pulse.

  • Presence of S4 and systolic murmur (contraction).

• Diagnostics:

  • ECHO: Reveals wall motion abnormalities, diastolic dysfunction.

    • Pts generally present with normal ejection fraction or slightly elevated.

  • ECG: Looks for dysrhythmias and conduction abnormalities.

  • Nuclear stress tests to evaluate aortic obstruction.

  • Heart cath

Nursing Care for Hypertrophic CMP

• Medications:

  • Beta-blockers and calcium channel blockers to reduce ventricular contractility.

  • Antidysrhythmic such as Amiodarone and Sotalol (potent beta-blocker, must ensure magnesium and potassium are good first otherwise infuse Mg and K BEFORE Sotalol).

• Complex Therapies:

  • Recognize the risk of SCD; consider AICD pacemaker.

  • Surgical options: Ventriculomyotomy and myectomy (remove part of thickened muscle), Percutaneous Transluminal Septal Myocardial Ablation (PTSMA) (burn some of septum).

  • Advise against strenuous exertion

  • Elevate lower extremities (LE) to bring blood flow back to heart to activate baroreceptors to decrease blood volume.

  • Avoid Nitroglycerin due to risk of hypotension.

    • Not taking enough blood volume into ventricle to begin with → nitro will decrease volume even more → decrease CO.

Restrictive Cardiomyopathy

• Overview:

  • Least common form of CMP.

• Causes:

  • Autoimmune or rheumatic diseases.

  • Amyloidosis (protein deposits) and sarcoidosis (inflammatory cell deposits).

  • Ventricular thrombus

  • Cancer (lung, lymphoma) and post-radiation therapy.

• Pathophysiology:

  • Characterized by stiff walls leading to impaired diastolic filling and stretch. Refilling problems.

    • Less blood into the heart → less blood out → less oxygen

      • Heart appears the same size as a normal heart but the walls are stiffened (diminished movement).

  • Myocardial fibrosis, hypertrophy, and infiltration.

Clinical Manifestations of Restrictive CMP

• Signs & Symptoms:

  • Fatigue and exercise intolerance.

  • Dyspnea (SOB) and orthopnea.

  • Angina and syncope (fainting).

  • Palpitations.

  • Signs of heart failure (HF): SOB (early unless at rest = late), edema (from lungs), weight gain (no more than <2g sodium, <2L fluid, <2 lbs per day), hepatomegaly (enlarged liver), JVD.

Diagnostics for Restrictive CMP

• ECHO: Shows normal ventricular size with thickened walls and a dilated right ventricle.

• Chest X-Ray (CXR): Can reveal normal or enlarged atria, pleural effusions, and pulmonary edema.

  • Enlarged atria due to overload to atria.

  • Increased vasculature fluid → moves into pleural space (pulmonary edema)

• ECG: Identifies dysrhythmias, commonly atrial fibrillation.

• Cath Lab Procedures: Endomyocardial biopsy (helpful only in first 6 weeks) and stress testing for exercise tolerance.

• Genetic test!

Nursing Care for Restrictive CMP

• Standard Treatment Protocols:

  • Improve diastolic filling.

  • Standard HF treatment (specifically for diastolic heart failure).

  • Assess for heart transplant eligibility.

Patient Education for CMP

• Medication Compliance: Ensuring adherence to prescribed therapies.

  • Find out why.

• Dietary Recommendations “Rule of 2s”:

  • Low sodium diet (<2 grams/day).

  • Fluid restrictions (<2 liters/day).

    • Fluid restriction if pt develops HF symptoms with CMP.

  • Weight gain (<2 lbs/day)

• Lifestyle Modifications:

  • Maintain reasonable weight, avoid cardiac stimulants and toxins (NSAIDs).

  • Stress management

  • Balance activity with rest periods, prioritize stress management.

    • Brisk 30 minute walk/30 minute moderate exercise x5 day a week.

• Monitoring:

  • Educate on warning signs of heart failure: weight gain, edema, SOB, fatigue.

  • Train caregivers in CPR fundamentals.

    • Especially if ejection fraction drops less than 30% → high risk of SCD.