Heart Failure Lecture Notes

Introduction

• Focus on congestive heart failure (CHF) within clinical medicine.
• Types of heart failure:
  • Left heart failure
  • Right heart failure
  • High output failure

Left Heart Failure

Types

1. Systolic Heart Failure (HFrEF)

   • Caused by reduced contractility of the left ventricular myocardium.
   • Common causes:
     • Myocardial infarction (MI) leading to fibrosis.
     • Dilated cardiomyopathy (ventricular thinning/weakness).
     • Myocarditis (less common).
   • Characterized by reduced ejection fraction (< 40%).
   • Results in decreased cardiac output.

2. Diastolic Heart Failure (HFpEF)

   • Caused by issues with ventricular filling due to high afterload.
   • Common causes:
     • Chronic hypertension.
     • Aortic stenosis.
   • Characterized by preserved ejection fraction (> 40%).
   • Results in decreased cardiac output due to reduced ventricular filling.

Compensatory Mechanisms

• Decreased cardiac output triggers increased systemic vascular resistance (SVR).
• Activation of sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS).
• Leads to increased heart rate, afterload, and potential ventricular remodeling.

Right Heart Failure

• Similar causes to left heart failure, with emphasis on increased pulmonary vascular resistance.
• Common causes:
  • Right ventricular MI.
  • Pulmonary hypertension (various types).
• Results in decreased right ventricular ejection fraction.
• Characterized by right ventricular hypertrophy and decreased filling.

High Output Heart Failure

• Defined by high cardiac output but insufficient to meet body's demands.
• Caused by conditions leading to systemic vasodilation:
  • Sepsis
  • Thiamine deficiency (beriberi)
  • Thyrotoxicosis
  • AV fistulas
  • Severe anemia
• Results in low systemic vascular resistance, triggering increased cardiac output.

Complications of Heart Failure

Left Heart Failure

• Pulmonary Congestion:
  • Leads to pulmonary edema, dyspnea, orthopnea, and hypoxia.
• Cardiogenic Shock:
  • Caused by acute triggers (MI, tachyarrhythmias).
  • Results in decreased systemic perfusion, organ malperfusion, and potential lactic acidosis.

Right Heart Failure

• Systemic Venous Congestion:
  • Leads to jugular venous distention, peripheral edema.
  • Potential liver congestion and failure, ascites.
• Cardiogenic Shock (less common):
  • Potential septal shift affecting left ventricular function.

Diagnosis of Heart Failure

• Chest X-ray: Check for cardiomegaly, pleural effusions, pulmonary edema.
• BNP Levels: Used to exclude CHF exacerbation.
• Echocardiogram: Assesses ejection fraction and ventricular function.
• Right Heart Catheterization: Measures pulmonary capillary wedge pressure (> 18 mmHg suggests left heart failure).
• EKG and Left Heart Cath: Consider for acute MI.

Treatment of Heart Failure

General Goals

• Reduce SNS and RAAS activity.
• Increase ANP activity.

Medications

• Beta-blockers & SGLT2 Inhibitors: Reduce SNS activity.
• ACE Inhibitors, ARBs, ARNIs: Reduce RAAS activity.
• Aldosterone Antagonists: Reduce fluid retention.
• Diuretics: Manage edema.
• Hydralazine and Isosorbide Nitrate: Alternative vasodilators.

Device Therapy

• CRT: For patients with left bundle branch block and reduced ejection fraction.
• AICD: For patients with ventricular arrhythmias.
• LVAD: For severe cases as a bridge to transplant.

Cardiogenic Shock Management

• Inotropes (Dobutamine, Milrinone): Increase cardiac output.
• Mechanical Support (IABP, VA-ECMO): For refractory cases.
• BiPAP: Reduces preload and afterload, helps mitigate pulmonary edema.

Conclusion

• Comprehensive understanding of heart failure pathophysiology, diagnosis, and treatment is crucial.
• Emphasis on personalized treatment plans and monitoring for potential complications.