Heart Disease and Lab Testing

The heart, a muscular organ that is in the region of the chest in between the lungs, is about the size of an adult fist. The job of the heart is to pump blood, and it can beat as much as 100,000 times per day. The blood carries nutritious oxygen and nutrients through the body, and it works to transport carbon dioxide and waste materials to the kidneys, lungs, and the liver. In these organs, the toxins are then removed from the body via natural processes.  

The heart makes sure that it has plenty of oxygen via coronary arteries and veins throughout the heart. It’s also a part of the endocrine system producing hormones called atrial natriuretic peptides or ANP. It also creates B natriuretic peptides or BNP that help to coordinate the function of the heart via the blood vessels and kidneys.  

Essentially, the heart is a hollow that has two vertically divided halves. These halves are divided by a septum, and either side has two internal chambers. The atrium is the top chamber, and the ventricle is the bottom chamber.  

As blood returns from the body, it is poor in oxygen. It enters via the veins on the right-hand side of the heart via the right atrium. It is then pumped into the right ventricle where it goes to the lungs and releases and accepts carbon dioxide and oxygen. This blood is now oxygenated, and it will return via the left atrium, where it will be pumped out of the left ventricle into the arteries and the rest of the body.  

Four valves regulate the blood flow as it goes through the heart chambers. As they open and close, you can hear the “lub-dub” sound via a stethoscope or if you lay an ear to someone’s chest. There is an electrical system that works to control the rate and the rhythm as the heartbeats.  

The myocardium is the heart muscle. There is an endocardium that is a membrane that lines the heart chambers as well as the valves. The pericardium is the outer layer membrane of the heart and works to secrete fluids. Finally, the pericardium works as a protective barrier that surrounds the heart and works to give it a friction-free environment.  

The term heart disease encompasses many medical conditions that affect the heart. Any condition that damages or decreases the heart supply of oxygen or can affect its efficiency can interfere with the relationship between the kidneys, heart, blood vessels, and more. It can also affect the rest of the body. Occasionally, heart conditions are present at birth or, they may develop over the course of the lifetime.  

Approximately 610,000 persons die annually of heart disease in the United States per the Center for Disease Control and Prevention. That’s approximately 1 out of every 4 people who die. At present, heart disease is the leading cause of death for both males and females.  

Common Conditions of The Heart 

Some common conditions of heart disease include: 

  • CHD or Coronary Heart Disease, and CAD or Coronary Artery Disease are two of the most common conditions. Typically, they’re a part of cardiovascular disease or CBD. The arteries in the heart become narrow over time, and eventually, more fatty deposits build-up and form plaque in the arteries. This is called atherosclerosis. This can greatly limit the amount of blood that flows through the arteries. In time, left unchecked, this can lead to angina, a stroke, or a heart attack.  
  • Intermittent chest pain is called angina. This is due to not enough blood and oxygen getting to the heart or ischemia. Typically, angina happens when most of the flow of blood is lost to a specific area in the heart. It can cause chest pain and worsen with exercise over time. The chest pain can develop during rest or even with minimal exertion and is called unstable angina.  
  • MI, myocardial infarction, or heart attacks are the death of the heart muscle cells due to lack or blocked blood flow in the arteries that give the oxygen to the blood. Such a condition can cause a sudden onset of pain in the chest. There are different reasons for this, including angina and heart attack.  
  • SCA or Sudden Cardiac Arrest is when the heart suddenly stops. If not treated in minutes, this can lead to death. The blood will cease flowing to the brain and the other vital organs of the body. 
  • CHF or Congestive Heart Failure happens when the heart isn’t as effective at pumping the blood through the body. It may not completely fill with blood or completely empty of blood. The oxygen levels to the other parts of the body will cease or be seriously decreased. Blood may back up into the hands, the legs, feet, liver, and the lungs. This can cause swelling, and the patient may develop shortness of breath and fatigue more easily. If it’s a temporary cause, heart failure may only be temporary; however, it’s typically a more chronic condition that will worsen over the course of time. Sometimes it can be improved with treatment.  
  • Cardiomyopathy 
  • Cardiomyopathy is a condition wherein the heart muscle is abnormal.  
  • Hypertrophic cardiomyopathy: one or even more of the walls within the heart thicken. 
  • Dilated cardiomyopathy: one or even more of the chambers in the heart dilate or enlarge.  
  • Restrictive cardiomyopathy: sometimes, abnormal materials accumulate within the heart wall, thus reducing the flexibility of the ventricle walls.  
  • Idiopathic cardiomyopathy: no obvious reason for the condition. 
  • Ischemic cardiomyopathy: lessened blood flow to the heart.  
  • Myocarditis is inflammation of the heart muscle. It can happen rapidly and have shortness of breath, an irregular heartbeat, and lead to heart failure rapidly.  
  • Pericardial disease is when the sac that surrounds the heart is diseased. This inflammation of the pericardium can lead to more rubbing or friction in the chest cavity and lead to pain.  
  • Endocarditis or inflammation of the membrane that lines the heart valves and the heart.  
  • Atrial fibrillation is an arrhythmia that can lead to a quivering sensation of irregular heartbeat. It can cause blood clots, heart failure, stroke, and other complications.  

Heart Valve Conditions: 

Prolapse happens when a portion of the valve in the heart protrudes into the atrium of the heart, which prevents a tight seal. This may lead to regurgitation or backflow of the blood. It may also lead to an increased chance of endocarditis.  

Stenosis or narrowing of the valve opening in the heart can affect the blood flow, depending on the valve that is affected. There is pulmonary valve stenosis, mitral valve stenosis, and aortic valve stenosis.  

Many conditions may be contributing factors to heart disease. Here are some examples: 

  • Alcohol Abuse 
  • Anabolic Steroid Use 
  • Amyloidosis (a rare progressive disorder that is caused by abnormal proteins termed amyloids that are produced and then deposited throughout the organs of the body). 
  • Atherosclerosis which are deposits that are comprised of mostly lipids happening on the walls of the arteries causing decreased blood flow. 
  • Autoimmune disorders 
  • Congenital (present at birth) defects. 
  • Diabetes 
  • Diets that are high in saturated fats or cholesterols. 
  • Drug use, including cocaine. 
  • Overexposure to chemicals and toxins, including mercury. 
  • Hypertension or high blood pressure. 
  • Bacterial, viral, or fungi infections. 
  • Trauma infections. 
  • Rheumatic fever (rarely in the United States now). 
  • Smoking cigarettes. 
  • Sedentary lifestyle habits. 
  • Thyroid dysfunction (over or underactive thyroid). 

Signs and Symptoms of Heart Disease 

Heart disease may develop over the course of time (chronic), or it may have a rapid onset (acute). It may also come and go. It may be rapidly progressive, or it may remain stable. There may be many causes or no obvious cause. The symptoms may often change or become worse over time.  

Chronic heart diseases may become acutely worse in time. Such conditions may resolve on their own, or they may worsen and become a life-threatening condition. 

Those who have early-onset heart conditions may have a few symptoms, including:  

  • Shortness of breath 
  • Fatigue 
  • Nausea 
  • Dizziness 
  • However, the symptoms don’t necessarily indicate that there is heart disease in the person. They may also be indicative of other medical conditions.  

As the disease continues and progresses, the signs and the symptoms may become worse and include other symptoms, including: 

  • Swollen feet, ankles, legs, or abdomen. 
  • Irregular heartbeats or changes in the heart rhythm. 
  • Pressure or discomfort (chest pain). 
  • Left shoulder, arm, jaw, or back pain. 
  • Dilation stretching of the heart chambers. 
  • Unable to produce enough oxygen and clear waste products from the blood and body while undergoing physical activities. 
  • Insufficient contractions of the heart, preventing it from completely and properly pumping blood. 
  • Ventricular hypertrophy or increased thickness of the heart walls that cause a decrease in the flexibility of the heart. 

Laboratory Blood Tests 

  • Screening for cardiovascular disease risks. 
  • Cardiac risk tests are done to screen out those who are asymptomatic. These tests help to determine the risk of the person for developing coronary heart disease. Cardiac risk assessments are a series of tests that determine the person’s risk and their health factors to indicate whether they are at risk for a stroke or a heart attack. These factors include the person’s age, genetics (family history), level of physical activity, and blood pressure.  

Such Lab Tests May Include:

Lipid Panels (levels of HDL-C, LDL-C, triglycerides, and cholesterol). Such tests measure the levels and types of lipids or fats in the blood. 

hs-CRP detects the low levels of the C-reactive proteins. These are markers for inflammation associated with atherosclerosis and other conditions. 

Lp(a) can potentially be used to detect elevated levels of lipoproteins. They can indicate modifications of LDL-C that denote increased risks of atherosclerosis. These tests may be done in combination with other routine lipid panels to gain more details and information.  

Other detailed tests may be considered regarding the markers for heart disease. You can read more here on Cardiac Risk Assessment. 

Diagnosing the Damage to The Heart from Heart Attacks 

When someone enters an Emergency room presenting with a possible heart attack, they are evaluated with a myriad of laboratory tests and blood tests to evaluate their condition. Such testing is utilized to determine the extent of damage and whether the person has had a heart attack or some other medical issue. For the treatments to be effective, they must be given to the person within a short time frame. The sooner the treatments are begun, the less damage there is to the heart. Thus, the diagnosis must be accurate.  

Some tests detect the proteins that are released when specific muscle cells are damaged. These are frequently called biomarkers, and they can be in specific orders when someone has a heart attack. There is chest pain, jaw pain, neck or abdominal pain, back pain that radiates to the arms or shoulders, as well as nausea, shortness of breath, and even lightheadedness.  

Tests 

  • Troponin or sensitivity to troponin tests is typically ordered to help to diagnose heart attacks and rule out other medical issues that may be very similar. Elevated troponins or slight elevations may be indicative of the amount of damage to the heart. If your levels are elevated, and they elevate over the course of several hours, then it’s potentially likely that you’ve had a heart attack. These levels will change within 3 to 6 hours after your heart is injured, and they may remain at these higher levels for as long as 10 to 14 days.  
  • CK-MB – CK and CK-MB used to be the main tests that were done to monitor or detect a heart attack. These were done if a troponin test wasn’t available. If the CK is elevated, then a CK-MB test could be used as a follow-up to determine the level of damage to the body. 
  • BNP or NT-pro BNP is released from the body in a natural response to heart failure. When the BNP levels increase, they may not be a true diagnostic for a heart attack, they may also indicate an increased risk for complications in those with ACS.  BNP is released when the heart is stretched. It’s measured in persons who have swelling in the legs or abdomen and shortness of breath. It can help to diagnose heart failure.  
  • Pericardial fluid analysis analyzes the fluids in the sac surrounding the heart. Doctors may be able to determine if there is fluid around the heart, causing heart issues.  
  • Blood cultures may also be done to determine if there is a heart infection or endocarditis. 

More heart tests may include the following: 

  • hs-CRP can determine the prognosis and whether there is a risk of a recurrence in coronary heart disease.  
  • Blood gases are performed to determine the levels of oxygen and carbon dioxide. 
  • A comprehensive metabolic panel or CMP is done to evaluate the function of the heart.  
  • Four electrolyte tests evaluate the fluid levels and salt balance. 
  • A complete blood count or CBC evaluates the blood cells and checks for anemia and infections.