NURSING REVIEW: Congestive Heart Failure Bullets

• Heart failure occurs when the heart’s pumping becomes impaired, resulting in inability to meet the body’s oxygen demands. The most common type of heart failure, left-sided failure, occurs when the left ventricle cannot contract sufficiently.
• Afterload is the amount of resistance the ventricle pumps against. In order to pump effectively, the ventricle must generate sufficient pressure to overcome this resistance.
• Left heart failure occurs when arteries downstream constrict, resulting in increased afterload: resistance too high for the ventricle to pump against.
• A heart attack can also cause left heart failure.
• In a failing heart, blood accumulates in the left ventricle causing pressure. This pressure, called preload, causes the ventricle to expand.
• Increased preload worsens the ventricle’s ability to pump. Accumulating blood stretches the cardiac muscle fibers, pulling myosin and actin filaments farther apart. When over-stretched, myosin molecules cannot connect with actin, the myosin–actin crossbridges cannot swivel.
• The inability of the crossbridges to swivel causes makes contraction weaker, reducing the likelihood that sufficient blood will be pumped. The progression of heart failure continues as blood accumulates.
• Built-up blood in the left ventricle causes a backup of blood throughout the pulmonary circuit, leading to pulmonary congestion. This associated congestion is responsible for left heart failure, also known as “congestive heart failure.”
• Blood build up in the lungs causes difficulty breathing, especially when a person is reclining. Pulmonary congestion also reduces the ability to oxygenate the blood, worsening systemic hypoxia.
• The progressive nature of congestive heart failure, if untreated, ultimately causes death.