The causes of heart failure are dependent on the location of the abnormality.

In the conduction system of the heart:

In the valve system of the heart:

Inadequate Preload:

In the heart muscle:

  • Weakened heart muscle (loss of contractility)
    • Dilated cardiomyopathy due to
      • Genetic mutations
      • Taurine deficiency
      • Tachycardia induced
      • Idiopathic
  • Impaired distensibility/relaxation
    • Concentric hypertrophy
      • Hypertrophic cardiomyopathy
      • Systemic hypertension
    • Myocardial infiltration
      • Neoplasia
      • inflammation

Infection of the heart:

  • Bacterial, viral, fungal, rickettsial, protozoal, heartworm


  • Left-to-right: volume overload via the recirculation system
  • Right-to-left: unoxygenated blood gains access to the systemic circulation