Understanding How Heart Failure is Diagnosed and Measured Over Time
The diagnosis of heart failure typically starts when a patient talks to their caregiver about the signs and symptoms they are experiencing. Their health care provider may ask questions designed to confirm the causes of heart failure that may be in their medical history as well.
The provider may order a series of diagnostic tests which may include one or more of the following:
- Blood tests
- Electrocardiogram (EKG)
- Chest X-ray
- Stress test
The last of these, the echocardiogram (or Echo), is perhaps the most informative of the tests in terms of diagnosing heart failure. An echo is a sort of picture of the heart taken with high-frequency sound waves (ultrasound) delivered through a hand-held wand placed on your chest. The resulting picture is a graphic depiction of the heart’s actual movements that healthcare providers can use to visualize the heart’s valves and chambers. Findings can help them to evaluate anatomical condition of the heart and it’s various structures, but among the most important measures of an echocardiogram is an evaluation of the heart’s pumping capacity.
The chambers of your heart fill and empty with each beat. The right ventricle pumps to supply the arteries of the lungs, and the left ventricle pumps to supply the rest of the body. An echocardiogram can reveal how much of the blood that fills the ventricles is pumped out with each beat. This measure is known as the ejection fraction or EF. In so called “systolic” heart failure, it is the ejection fraction of the left ventricle (LVEF) that means the most.
People with a healthy heart have an LVEF of 50% or higher, which means that more than half the blood in your ventricle is pumped to your body on each beat. When your ejection fraction is under 40%, it is considered a compromised ejection fraction and may be an indicator of heart failure. In some cases heart failure can occur even with a normal ejection fraction. This happens if the heart muscle becomes stiff from conditions such as high blood pressure. In any case, your healthcare provider will use the LVEF measure to make appropriate medical decisions about how to help you care for your heart failure and may even communicate the exact percentage with you.
Once you are diagnosed as living with heart failure, your healthcare provider will occasionally ask questions designed to evaluate how capable or willing you are to engage in the daily activities that healthy people of your age typically participate in. The answers to these questions allow your provider to use well-established classification systems to manage your ongoing care. The two most common classification systems are the New York Heart Association (NYHA) classification which uses a symptom-based scale with four categories ranging from Class I to Class IV., and the American College of Cardiology/ American Heart Association (ACC/AHA) scale which uses a stage-based classification system using the letters from A through D. These classification systems are not independent of each other. Your physician will often use them together to help decide the most appropriate treatment option for you. You should ask your physician about your classification to understand the severity of your heart failure.
“A large percentage of patients have primary cardiomyopathy, which is just a medical term for weakening of the heart muscle. That can be caused for a variety of things, including infections, toxic agents, exposure to toxins, as well as to genetic or inherited conditions.”
Classes of Heart Failure
Doctors usually classify patients’ heart failure according to the severity of their symptoms. The table below describes the most commonly used classification system, the New York Heart Association (NYHA) Functional Classification1. It places patients in one of four categories based on how much they are limited during physical activity.
|I||No limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea (shortness of breath).|
|II||Slight limitation of physical activity. Comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea (shortness of breath).|
|III||Marked limitation of physical activity. Comfortable at rest. Less than ordinary activity causes fatigue, palpitation, or dyspnea.|
|IV||Unable to carry on any physical activity without discomfort. Symptoms of heart failure at rest. If any physical activity is undertaken, discomfort increases.|
|A||No objective evidence of cardiovascular disease. No symptoms and no limitation in ordinary physical activity.|
|B||Objective evidence of minimal cardiovascular disease. Mild symptoms and slight limitation during ordinary activity. Comfortable at rest.|
|C||Objective evidence of moderately severe cardiovascular disease. Marked limitation in activity due to symptoms, even during less-than-ordinary activity. Comfortable only at rest.|
|D||Objective evidence of severe cardiovascular disease. Severe limitations. Experiences symptoms even while at rest.|
- A patient with minimal or no symptoms but a large pressure gradient across the aortic valve or severe obstruction of the left main coronary artery is classified:
- Function Capacity I, Objective Assessment D
- A patient with severe anginal syndrome but angiographically normal coronary arteries is classified:
- Functional Capacity IV, Objective Assessment A