Heart failure: Nursing pathophysiology

Heart failure sometimes also called congestive heart failure is a condition that occurs when the heart can't pump enough blood to meet the body's demands.

Heart failure can be either systolic or diastolic and it can affect the right left or both sides of the heart. In systolic heart failure, the heart is unable to effectively contract to push blood out of the ventricles.

Whereas with diastolic failure, the ventricles become stiff and unable to relax between beats so they can't fill with blood properly.

Now, the heart acts as a pump to move deoxygenated blood through the right side of the heart to the lungs for oxygenation, back to the left side of the heart and then out to the body.

Each beat of the heart has two phases. Systole and diastole, systole is when the heart is contracting and pumping blood.

And dios Tole is when the heart is relaxed and filling with blood. The amount of blood pumped by the heart in one minute is called cardiac output.

And it's an important indicator of heart function. Cardiac output is determined by four factors, contractility, preload, afterload and heart rate, contractility is the heart's ability to contract and eject blood during systole, which enhances the force of contraction during systole preload is the amount of stretch in the ventricles at the end of diastole.

As the ventricles fill with blood. In general, the more the preload, the stronger the contraction.

On the other hand, afterload is the resistance the ventricles must push against during systole. Less afterload can decrease workload on the heart.

Lastly, heart rate is the number of times the heart BPM. Ok.

So cardiac output is calculated by multiplying the heart rate by stroke volume, which is the amount of blood pumped by the heart during systole.

Now, the amount of blood within the ventricles at the end of diastole is called the end diastolic volume. And the stroke volume is just a portion of the end diastolic volume.

Similarly, the percentage of the enddiastolic volume pushed out of the ventricles with each contraction is called the ejection fraction.

A normal ejection fraction can vary but it typically ranges between 50 70%. It's calculated by dividing the stroke volume by the end diastolic volume and multiplying by 100 to get a percentage in general.

The higher the ejection fraction, the more blood is being pumped to the body. The cause of heart failure is usually secondary to another condition that impairs the heart's ability to contract or relax effectively.

These include coronary artery disease, hypertension or valvular heart disease. Risk factors for heart failure can include advanced age and history of cardiac disease.

Ok. So in systolic heart failure damage occurs to the cardiac muscles which weakens them and decreases contractility with less contractility.

Stroke volume decreases as does cardiac output and ejection fraction. For example, if the stroke volume is 44 mL and the enddiastolic volume is 110 mL.

The ejection fraction is only 40%. This is why systolic heart failure is also sometimes known as heart failure with reduced ejection fraction or hef ref.

Now, in diastolic heart failure, there's usually increased peripheral vascular resistance or the resistance in the circulatory system that increases afterload.

As the heart tries to overcome the resistance, it increases its contractility which ultimately increases the heart's workload even more over time.

This increased workload leads to hypertrophy or thickening of the heart walls, making them more rigid and less elastic. The rigidity restricts relaxation of the ventricles during diastole and decreases ventricular filling, thereby decreasing preload.

This causes the stroke volume and enddiastolic volume to decrease while the ejection fraction remains normal. For example, if the stroke volume is 44 mL and the enddiastolic volume is 69 mL, the ejection fraction is 64%.

This is why diastolic heart failure is also sometimes called heart failure with preserved ejection fraction or he path clinical manifestations depend on which side of the heart is affected.

In general, heart failure can manifest with signs and symptoms related to chronic hypoxia or low oxygen in the body tissues because the heart can't supply enough oxygen rich blood.

These include fatigue, dyspnea, exercise, intolerance and dizziness. Tachycardia may also occur as the body attempts to pump more blood to meet the body's demands.

And oliguria or low urine output can be present because the kidneys receive less blood flow. Additionally, extra heart sounds like S3 and S four can be heard with progressive heart failure due to changes in blood flow and contractility.

Now, when the right side of the heart is affected, manifestations are related to blood backing up into systemic circulation and include peripheral edema, weight gain and ascites, which is a buildup of fluid in the peritoneal cavity, hepatosplenomegaly and distended.

Neck veins can also occur conversely when the left side of the heart is affected, manifestations are related to blood backing up into pulmonary circulation and can include cough with frothy sputum that is white, pinkish or blood tinged crackles in the lungs and orthopedia or difficulty breathing when lying flat.

All right. As a quick recap, heart failure is a condition that occurs when the heart can't pump enough blood to meet the body's demands.

Heart failure can be either systolic or diastolic and it can affect the right left or both sides of the heart. Heart failure usually occurs secondary to other cardiovascular conditions.

Clinical manifestations are related to chronic hypoxia and systemic and or pulmonary congestion