Heart Failure

Heart Failure: Definition

  • Heart Failure (HF) is a complex clinical syndrome from any structural/functional impairment of ventricular filling or ejection of blood. Echo evidence of abnormalities with inadequate cardiac output to meet metabolic needs.

Scope & Epidemiology

  • Affects > 6.2%20million6.2\%20million Americans.
  • Mortality: ≈50%\approx 50\% within 5 years5\text{ years} of diagnosis.
  • Highest admitting diagnosis for hospitalization; ~1 million1\text{ million} hospital admits/year; 550,000550{,}000 new diagnoses/year.
  • Re-hospitalization near 30%30\% within 60–90 days of discharge.
  • HF costs estimated at $30.7 billion\$30.7\text{ billion} per year.

Prevalence & Risk Factors

  • Lifetime risk for HF from age 45 to 95 ranges 20%−45%20\%-45\% (NHANES).
  • Primary risk factors: CAD,MI,hypertension,diabetesCAD, MI, hypertension, diabetes.
  • Contributing: age, ischemic heart disease, tobacco, sedentary lifestyle, obesity, high cholesterol, renal failure, depression, socioeconomic factors.

Etiology

  • Cardiac causes: hypertension, CAD, valvular disease, myocarditis, cardiomyopathies.
  • Non-cardiac causes: pulmonary embolism, pulmonary hypertension, alcoholic cardiomyopathy, sleep apnea, thyroid dysfunction, nephrotic syndrome, COVID-19, toxins, anemia, hemochromatosis, amyloidosis, sarcoidosis.

Cardiac Performance & Hemodynamics

  • Key determinants: preload,afterload,contractility,heartrate,strokevolumepreload, afterload, contractility, heart rate, stroke volume.
  • Cardiac output: CO=HR×SVCO = HR \times SV.
  • Autonomic & neurohumoral regulation (baroreceptors, RAAS, natriuretic peptides).

HF Etiology by Preload/Afterload

  • Increase preload: fluid overload, pulmonary emboli, septal defects, regurgitations, corpulmonale, pregnancy.
  • Decrease preload: valve stenosis, tamponade, constrictive pericarditis.
  • Increase afterload: hypertension, high vascular resistance, valvular stenosis; CAD/ischemia; endocrine causes.
  • Aging effects: arterial stiffness, diastolic dysfunction risk, valve calcification, altered responsiveness.

Types of Heart Failure

  • Left ventricular failure (CHF): Systolic vs Diastolic.
  • Right ventricular failure.
  • Mixed failure.
  • High-output failure.
  • Acute vs chronic HF.

Left Heart Failure: Systolic vs Diastolic

  • Systolic HF (Non-preserved EF): EF < 50\%; decreased forward flow/CO.
  • Diastolic HF (Preserved EF): EF=50%−70%EF = 50\%-70\%; impaired filling due to stiff ventricle.
  • Right-sided HF often accompanies left HF or occurs with isolated right failure.

Left Heart Failure: Systolic Pathophysiology

  • Inadequate CO due to reduced contractility, MI, cardiomyopathies, myocarditis, ischemia.
  • Ventricular remodeling with increased workload over time; inflammatory and neurohumoral changes.
  • EF values: Normal EFnormal≈55%−65%EF_{normal} \approx 55\%-65\%; HF with reduced EF EF≈10%−45%EF \approx 10\%-45\%.

Left Heart Failure: Remodeling & Geometry

  • Injury leads to remodeling: increased wall thickness to reduce wall stress; dilation of LV; spherical geometry; hypertrophy.
  • Remodeling associated with neurohumoral activation and fibrosis.

Neurohumoral Activation in HF

  • Catecholamines & sympathetic stimulation.
  • RAAS activation: renin, angiotensin II, aldosterone, ADH.
  • Natriuretic peptides (BNP/ANP) and counter-regulatory mechanisms.
  • Consequences: edema, fibrosis, adverse remodeling, reduced contractility.

Factors in Cardiac Remodeling (RAAS Axis)

  • Angiotensinogen —> Angiotensin I —(ACE)→ Angiotensin II → aldosterone, vasoconstriction.
  • Effects: Na+/water retention, increased BP, vascular remodeling.

Aging & HF

  • Age-related changes increase susceptibility: vascular stiffness, diastolic dysfunction, valve calcification, salt sensitivity.

Adequate Circulating Volume & Forward Flow

  • Determinants: preload, contractility, afterload, HR, SV, CO.
  • Peripheral/arterial tone & microcirculation regulate tissue perfusion.
  • Volume status influences preload and venous return.

Types of Heart Failure (Recap)

  • Left HF: Systolic (reduced EF) vs Diastolic (preserved EF).
  • Right HF: venous congestion with systemic edema.
  • Mixed HF: both ventricles dilated; high pulmonary pressures.
  • High-output HF: adequate or high CO but failure to meet metabolic needs.

Clinical Manifestations

  • Left HF: dyspnea, orthopnea, paroxysmal nocturnal dyspnea, pulmonary edema, crackles, S3/S4, tachycardia.
  • Right HF: peripheral edema, JVD, hepatomegaly, ascites, weight gain.

Diagnostic Tests

  • Echocardiogram, chest X-ray, ECG, MRI, stress test/holter, coronary angiography, biopsy when indicated.
  • Labs: BNP/NT-proBNP, troponin, electrolytes, BUN/creatinine, LFTs.

Collaborative Goals of Treatment

  • Decrease intravascular volume and venous return/preload.
  • Decrease afterload; improve gas exchange/oxygenation.
  • Improve cardiac function; reduce anxiety and oxygen demand.
  • Decrease mortality and improve quality of life.

Pharmacological Management: Core Concepts

  • Decrease fluid volume: diuretics (furosemide); mineralocorticoid antagonists (spironolactone, eplerenone); vasodilators; natriuretic peptides; ARNI (sacubitril/valsartan).
  • Decrease preload: venodilators (isorbide dinitrate, nitroglycerin); Nesiritide; morphine (historical role).
  • Decrease afterload: ACE inhibitors, ARBs, ARNIs; hydralazine; beta-blockers (carvedilol, metoprolol, bisoprolol); IV nitroprusside; IV morphine (if used).
  • Relax myocardium in diastolic HF: calcium channel blockers (Diltiazem, Amlodipine, Felodipine).
  • Improve contractility: digoxin; dobutamine; milrinone; vasopressors in shock (epinephrine/norepinephrine) but with higher myocardial demand.
  • SGLT2 inhibitors: beneficial in HF regardless of diabetes status; natriuresis/diuresis, remodeling, diastolic function, BP reduction, possible erythropoiesis effects.

Special Topics

  • HF with Diabetes: higher HF risk; cautious glycemic control; some antidiabetic meds may affect HF risk differently.

Monitoring & Follow-Up

  • Weight monitoring: signs of fluid retention; thresholds 2 lb/24 h2\text{ lb/24 h} or 5 lb/week5\text{ lb/week} gain.
  • BP targets: < 130/80 \text{ mmHg} when appropriate.
  • Sodium restriction: ≤2 g/day≤ 2\text{ g/day} (approx. ≤2300 mg Na/day\leq 2300\text{ mg Na/day}).
  • Vaccinations and regular follow-up to prevent decompensation.

Devices & Advanced Therapies

  • Implantable cardioverter-defibrillators (ICDs) for sudden death risk.
  • Cardiac resynchronization therapy (CRT) in select patients.
  • LifeVest as external defibrillator option.

Nursing Care & Patient Education

  • Monitor vitals, pulmonary/CV status, labs; adjust therapy per protocol.
  • Diet: restrict Na; monitor fluid status and electrolyte balance.
  • Activity pacing; energy conservation; educate on medication adherence and symptom monitoring.
  • Education on recognizing signs of decompensation and when to seek care.

Prevention & Readmission Reduction

  • Lifestyle: healthy diet (DASH/Med), regular physical activity, smoking cessation, weight management.
  • BP control to target; lipid management as appropriate; glycemic control in diabetes with HF considerations.
  • Identify and address non-cardiac factors contributing to readmission (infections, COPD, etc.).

NYHA & ACC/AHA Classifications (Overview)

  • NYHA: I–IV functional class (symptom burden with activity).
  • ACC/AHA: Stages A–D (risk to advanced disease; structural disease with/without symptoms).

Quick Practice Questions

  • How does increased preload versus increased afterload affect LV performance?
  • What EF thresholds define systolic vs diastolic HF?
  • List 2–3 first-line pharmacologic options to decrease mortality in HFrEF.
  • Name a device therapy option for selected HF patients.