Structural Cardiac Disorders — Cardiomyopathy

Cardiomyopathy refers to progressive diseases of the myocardium that impair cardiac output and can lead to congestive heart failure. The three main types are:

• Dilated — enlarged chambers with thin, weakened muscle walls.
• Hypertrophic — thickened ventricular septum and smaller chamber space.
• Restrictive — stiff myocardium limiting filling and contractility.

All types reduce the heart’s pumping ability and may result in heart failure, arrhythmias, or sudden cardiac death.

Sodium (Na⁺) is the major electrolyte implicated in cardiomyopathy. Fluid volume overload and sodium retention contribute to worsening heart failure and elevated preload.

• History of chest pain, syncope, fatigue, or activity intolerance.
• Medication and dietary compliance, especially sodium restriction.
• Psychosocial factors — anxiety, depression, family impact, stressors.
• Physical findings:
  • Vital signs, blood pressure trends.
  • Heart sounds — murmurs, S₃ or S₄.
  • JVD, peripheral edema.
  • Pulmonary crackles (fluid overload).

• Heart failure (especially left-sided).
• Ventricular or atrial arrhythmias (A-fib/flutter).
• Conduction defects (PR/QRS changes).
• Pulmonary or cerebral embolism.
• Valvular dysfunction.

• Improve cardiac output and peripheral perfusion.
• Increase activity tolerance and independence with ADLs.
• Reduce anxiety and enhance sense of control.
• Promote effective self-care and lifestyle adaptation.

• Educate on balancing rest, activity, and work.
• Involve family in care and adjustment to lifestyle changes.
• Teach CPR and use of emergency devices (e.g., AED if indicated).
• Encourage support group participation and counseling.

• Stable vital signs and absence of dyspnea or weight gain.
• Improved activity tolerance (can perform ADLs).
• Reduced anxiety and understanding of self-management.
• Engagement in lifestyle modification and dietary adherence.

Pathophysiology

Ventricular chambers enlarge and myocardial wall thins, reducing contractility and ejection fraction. Blood backs up into the lungs → pulmonary congestion → decreased systemic output.

Manifestations

• Left-sided heart failure symptoms: dyspnea, crackles, confusion, chest pain.
• Progresses to right-sided failure: peripheral edema, ascites, JVD.

Diagnostics

• Coronary angiogram (to rule out ischemic cause).
• Echocardiogram (chamber size, EF, function).
• Chest X-ray (pulmonary congestion).
• Labs: CBC, BMP, Mg, cardiac biomarkers, BNP (>100 = HF).

Management (ABCD Approach)

• A — ACE inhibitors: “-pril” drugs to relax vessels and lower BP.
• B — Beta-blockers: “-lol” drugs to slow heart rate and reduce workload.
• C — Calcium channel blockers: e.g., diltiazem, nifedipine to promote relaxation.
• D — Digoxin & Diuretics: strengthen contraction and reduce fluid overload (e.g., furosemide, HCTZ).

Lifestyle (ADDRESS)

• A — Activity (moderate, rest as needed)
• D — Diet (2g sodium restriction)
• D — Drug adherence
• R — Rest and stress reduction
• E — Exercise as tolerated
• S — Stop smoking
• S — Stress management

Pathophysiology

Stiff, noncompliant myocardium limits ventricular filling and contraction, causing reduced cardiac output and pulmonary/systemic congestion.

Causes

• Genetic or idiopathic.
• Post-radiation therapy.
• Infiltrative diseases (e.g., amyloidosis).

Diagnostics

• Echo (diastolic dysfunction).
• MRI for tissue characterization.
• Labs similar to dilated form.

Management

• Supportive: manage HF symptoms (diuretics, ACE inhibitors).
• Reduce radiation exposure if applicable.
• Monitor for arrhythmias and embolic events.

Pathophysiology

Thickened septum obstructs outflow through the aortic valve, reducing systemic perfusion and risking sudden cardiac death (especially in young adults).

Diagnostics

• Echocardiogram — markedly thick septal wall.
• Biopsy — myofibril disarray.
• Normal lung sounds but reduced filling on echo.

Management

• Goal: lower heart rate and BP to reduce obstruction.
• Medications:
  • Beta-blockers (slow heart rate).
  • Calcium channel blockers (increase relaxation).
• Avoid the “Three D’s”:
  • Vasodilators (e.g., nitroglycerin).
  • Digoxin.
  • Diuretics (can worsen obstruction).
• Avoid heavy lifting, sudden position changes, or burst exertion.
• Monitor for weight gain >3 lbs in 2 days or >5 lbs in a week; report to provider.

Procedures

• Intra-aortic balloon pump for temporary support (cardiogenic shock).
• LVAD (left ventricular assist device) as bridge to transplant or permanent support.
• Heart transplantation in end-stage cases.

ACE Inhibitors

• Risk for hyperkalemia; monitor K⁺ and ECG for peaked T waves.
• Monitor for angioedema—especially first 30 minutes of first dose.
• Check BP before giving; risk for first-dose hypotension.

Digoxin

• Therapeutic range: 0.5–2 ng/mL. Hold if above or if HR < 60 bpm.
• Low potassium increases risk of toxicity.
• Signs of toxicity: visual halos, nausea, vomiting, bradycardia.