Cardiac Output & Cardiomyopathy

• Normal cardiac output ranges from 4-8 Liters of blood/minute
• Cardiac output is the volume of blood the heart pumps to allow the body to work

4 Components of Cardiac Output

• Cardiac output is affected by stretch or filling, resistance or pressure, filling time, and how hard the muscle contracts
• Fluid volume overload causes an increase in preload
• Vasoconstriction causes an increase in afterload.
• Tachycardia causes a decrease in CO (cardiac output) because the ventricles don't have enough time to fill
• Dypsnea or Diminished preload causes a reduction of preload.
• Vasodilation causes a decrease in afterload.
• Bradycardia causes decreased cardiac output because not enough blood is circulating to meet the body's demands
• Electrolytes, specifically sodium, affect how hard the muscle contracts

Cardiomyopathy

• Cardiomyopathy refers to diseases of the heart muscle that impair it's ability to pump blood

• Most common type of cardiomyopathy is dilated cardiomyopathy

• Impaired ventricular contraction or impaired ventricular relaxation may result from the disease

• Cardiomyopathy may be genetic or acquired

• Impaired ventricular contraction is associated with Heart Failure, reduced Ejection Fraction (HFrEF) and causes structural deformity. It impairs ventricular emptying.

• Patient education should include the same recommendations for both types of cardiomyopathies

Heart Failure

• Heart failure is when the heart muscle can't pump enough blood to meet the body's demands, resulting in reduced cardiac output

Left Sided Heart failure

• Left-sided heart failure involves systolic and diastolic issues.
• Systolic heart failure results from a problem with contraction.
• Left ventricle is weak and enlarged in systolic heart failure
• Diastolic heart failure results from a problem with filling/relaxation
• Left ventricle is stiff and thick in diastolic heart failure
• Ejection Fraction (EF) should be between 55-65%.
• Reduced Ejection Fraction heart failure is also known as HFrEF
• Clinical manifestations of left-sided heart failure include:
  • Dyspnea or shortness of breath
  • Cough
  • Crackles in the lungs
  • Pulmonary edema

Right Sided Heart Failure

• Reduced cardiac output from the right side of the heart causes systemic issues
• Systemic issues from right sided heart failure
  • Edema in the lower extremities.
  • Jugular venous distension (JVD)
  • Ascites
• When right-sided heart failure is caused by pulmonary hypertension it is called Cor Pulmonale
• Clinical manifestations of right-sided heart failure include:
  • Peripheral edema
  • Ascites
  • Hepatomegaly
  • JVD

Classification of Heart Failure

• Class I heart failure includes patients with no symptoms

• Class II heart failure includes symptoms with moderate exertion

• Class III heart failure includes symptoms with minimal exertion

• Class IV heart failure includes symptoms at rest

• Reduced cardiac output can causes activation of the RAAS (renin-angiotensin-aldosterone) system and sympathetic nervous system

• These compensatory mechanisms worsen heart failure instead of helping, as they increase afterload, cause vasoconstriction, and fluid retention

Pharmacological Treatments for HFrEF

• Shown to reduce mortality in Heart Failure with reduced ejection fraction (HFrEF)
  • Angiotensin Receptor Neprilysin Inhibitors (ARNI) OR Angiotensin-converting-enzyme (ACE) Inhibitors OR Angiotensin Receptor Blockers (ARB)
  • Beta Blockers such as Metoprolol
  • Mineralocorticoid Receptor Antagonists (MRA) such as Spironolactone
  • Sodium-glucose cotransporter-2 (SGLT2) inhibitors such as Canagliflozin
• All heart failure patients need to be on at least two of these medications before discharge:
  • An ARNI OR ACE Inhibitor OR ARB
  • AND a Beta Blocker