What is Heart Failure?
We need to start with a brief ‘primer’ on heart function. The blood comes back from the body in need of oxygen and enters the heart via the right atrium. It is then pumped into the right ventricle then directly into the lungs for oxygen. After receiving oxygen the blood returns to the heart’s left side into the left atrium and then into the left ventricle. The left ventricle is the “workhorse of the heart”. The walls of the left ventricle are very thick compared to the right ventricle.
What are the Symptoms and Effects of Heart Failure?
By way of an echocardiogram (a sonar of the heart), we can measure how much blood is pumped out of the left ventricle with each beat. This is called an ‘ejection fraction’ or EF. The left ventricle fills with only 120 cc or 4 oz of oxygen-rich blood from the left atrium which received it from the lungs. ‘Normal’ ejection fraction is 55-60% or 2 oz/beat. We often see an ‘EF’ (ejection fraction) ranging from 10-50%. So with an EF of 10%, there is only 12 cc or a ¼ oz ejected from the left ventricle with each beat!
The left ventricle normally pumps out 2 ounces/beat to the body. If the heart empties less than 2 oz/beat this means the heart is not emptying. When this happens there is backward ‘congestion’ into the organs. The blood can back up into the liver: your pants get tight, the abdomen becomes bloated, you can get nauseated and lose your appetite. Fluid can back up into the legs and they swell. The swelling can be in the feet and extend up the legs and into the scrotum. Fluid can back up into the lungs causing shortness of breath. You may develop crackles in the lungs which we can hear with a stethoscope, cough up pink-tinged sputum and require more oxygen. At night you can develop PND (paroxysmal nocturnal dyspnea). When you go to bed at night and are lying flat there is no gravity to keep the blood in your legs. More blood circulates throughout the body and into the lungs. This congestion often wakes you up struggling to breathe. As soon as you sit or stand up then gravity wins the battle and the blood gravitates out of the lungs and into the legs. Fluid can also back up into your head causing confusion and impairment of memory. All four of these organs can be affected or just one.
How do we Diagnose Heart Failure?
Heart failure is diagnosed often by symptoms of fluid overload, exam findings of fluid overload, and test results which indicate a weak or stiff heart and/or fluid overload.
Tests to clarify the cause of heart failure: Stress test to look for ECG changes while exercising, heart cath (angiogram) to look for blockages in the coronary arteries, echocardiogram (sonar or ultrasound of the heart) to look at the function of the valves and regurgitation, and a thyroid panel.
An ECG is also done to look at the heart’s electricity. Many rhythms can cause heart failure such as AFib (atrial fibrillation).
To evaluate the degree of heart failure we can draw a lab test called a BNP (brain natriuretic peptide) and do a CXR. When the heart starts to fail the ventricle begins to stretch and secretes a hormone called BNP. The heart starts to change shape- we call this ‘remodeling’. We can measure the BNP which correlates with the amount of excess fluid you have on board. The CXR can reveal fluid in your lungs which has backed up from your heart.
To keep medications safe we also do lab tests. Many of the meds we use can eliminate fluid such as Lasix, which is good but these meds can stress the kidneys and we can see this with blood work.
How can I get more information?
In the next blog, we will explore the treatment of HF.
We have a bi-monthly free class taught at SDCA on CHF. It is offered to the community. Please call to sign up at 303-744-1065. See you there!
Content by Vicki Petts, RN (SDCA heart failure nurse)