How It Works | Types of Heart Diseases | Diagnosing Heart Disease | Heart Specialists | Next Steps
The heart is a vital organ that acts as a pump, delivering blood to the rest of the body through a network of arteries and veins. Its function is essential to life: blood contains nutrients, such as oxygen, that the body’s tissues need to do their jobs. As blood circulates throughout the body and oxygen is used up, the heart pumps more blood to the lungs, where air exchange replenishes the blood’s oxygen content.
To do its job properly, the heart depends on several factors: the size and strength of its muscle, the amount of nutrients and oxygen it receives, the rate at which it pumps, and the condition of the blood vessels it’s pumping out to.
How does the heart pump blood?
The heart contains four chambers: two atria and two ventricles. It also has two sides: the left side of the heart receives oxygen-rich blood from the lungs and delivers it to the rest of the body; the right side of the heart receives oxygen-depleted blood from the body and delivers it to the lungs. The left and right sides are separated by a wall of muscle called the septum.
As a muscle, the heart contracts and relaxes, normally in a predictable sequence called sinus rhythm. When the heart relaxes, the inner space of the chambers expands and allows for blood to flow in; when the heart muscle contracts, the space narrows and blood is pushed out of the heart into the rest of the body.
The delivery network through which the heart pumps blood to the body is made up of vessels, called arteries and veins. Arteries are the vessels through which the heart pumps to the rest of the body; veins are the vessels through which blood returns to the heart, to be circulated again.
What are common diseases involving the heart?
When trying to understand heart diseases, it can be helpful to think of them in broad categories, depending on how the heart is affected.
Cardiomyopathies: Conditions that damage the heart muscle are called cardiomyopathies. The muscle can become too weak, too thick, or too stiff. In some cases, the muscle may repair itself, but in others, the damage may be so great that it interferes with the heart’s ability to pump. Common causes of cardiomyopathy include chronic high blood pressure, viral infections, and genetic conditions.
Cardiovascular disease: Over time, fatty cholesterol deposits can deposit in the inner walls of arteries. This process is called atherosclerosis. Risk factors that accelerate atherosclerosis include high blood pressure, high cholesterol, and tobacco smoking. As the fatty deposits increase, the inner space of the blood vessels decreases, making it harder for blood to flow through. The heart has its own supply of arteries—the coronary arteries—that deliver oxygen and nutrients to itself. If a coronary artery becomes too blocked off, blood flow is compromised to the heart and the heart tissue dies—leading to a heart attack.
Rate and Rhythm disorders: In order to pump blood effectively, the heart must maintain a steady rate and rhythm. The normal resting rate of the heart lies between 60-100 beats per minute. The rhythm is normally controlled by an area of the heart tissue called the SA node, which sends out electrical signals to the rest of the heart, telling it how fast it should beat. When the heart’s rhythm is thrown into disarray, the disorder is called an arrhythmia. Atrial fibrillation is a common rhythm disorder where the heart beats too fast and irregularly, leading to inefficient pumping of blood and formation of blood clots. Factors that cause rhythm disorders can include electrolyte abnormalities, defects in the heart structure, thyroid disease, and improper functioning of the heart’s natural pacemaker (SA node).
Valve Disorders: Just as the heart has four chambers, it also contains four valves—gates which open and close during the heart’s pumping cycle to allow blood to flow from each chamber to the next. When the valves function improperly—opening or closing when they shouldn’t—the circulation of blood flow can become compromised. The aortic valve, for example, allows for blood to leave the heart and go to the rest of the body; if the aortic valve becomes closed off (a condition called aortic stenosis), it can strangulate the blood circulation to the body—leading to fatigue and blacking out (syncope). Causes of valvular disease include congenital valve abnormalities acquired at birth, viral infections, and age-related valve changes.
Heart Failure: If any of the above disorders go untreated or become severe enough, the heart may not be able to do its job of pumping blood effectively. This is called heart failure. When the heart fails, blood can pool up in areas of the body, such as the lungs or legs, leading to shortness of breath or swollen legs. Fatigue is also common, as oxygen delivery to the rest of the body is compromised.
While heart disease can come in many forms, much of it can be prevented with healthy habits and regular check-ups. A balanced diet and exercise can keep the heart in shape and well-nourished, and simple tests like blood pressure and heart rate checks can help identify issues early, before things get too serious.
Sometimes, even the best preventive measures can’t stop heart disease from developing. In those cases, it’s best to seek out the heart specialist most appropriate for the particular type of heart disease.
How is heart disease diagnosed?
A variety of diagnostic tests and tools exist to aid in diagnosing heart disease.
- A stethoscope (auscultation) can help physicians hear the heart’s rate and rhythm to determine whether it is beating normally, whether blood is flowing correctly through the valves, or if the valves themselves are damaged.
- EKGs show the functioning of the heart's electrical system. Twelve electrodes are carefully placed on the skin to pick up the electrical pattern of the blood as it flows from the heart and through the body. Changes in the heart's electrical signature on an EKG may indicate a previous heart attack or other cardiac condition.
- X rays can reveal the heart's physical structures.
- CAT or CT scans can help with the detection of coronary artery disease by highlighting areas of increased density within the heart. The plaque or calcifications that form with coronary artery disease are quite dense and therefore visible on a CAT scan.
- Echocardiography relies upon ultrasound technology to image the heart and is used to diagnose a range of types of heart disease. Sound waves are transmitted to the heart from a device called a transducer, which is applied to the skin. Once the waves reach the heart, they bounce back across the skin and are stored in a computer.
- Doppler ultrasound, which depicts blood flow, is another adaptation of ultrasound testing. It is used to diagnose the location and degree of valvular blockages and leaks, as well as the presence of heart muscle (pericardial) disease.
- MRI has traditionally been used to assess anatomy and heart muscle function, as well as to identify the presence of any scar tissue in the musculature. In particular, MRI scanning can help distinguish between muscle that is impaired but can be improved through medical therapies, surgery, or angioplasty, and muscle that has turned permanently into scar tissue.
- MRA is specifically designed to detect coronary artery disease, identifying plaque in the arterial system and determining degrees of narrowing. It can also highlight so-called vulnerable plaques that may not noticeably limit blood flow, but have the potential to suddenly rupture and unexpectedly close an artery.
What kinds of doctors treat heart disease?
Heart health providers span a variety of specialties, which means it can be difficult to know what kind of specialist fits your health needs. Here are some of the common heart providers and the services they offer:
A preventative cardiologist is the first line of defense in heart health beyond general internists, primary care providers (and often gynecologists for women). In an office visit, these physicians will screen for risk factors for heart disease, including: weight, blood sugar, cholesterol, blood pressure, and smoking history. A physical exam, during which the physician will listen to your heart and carotid arteries in your neck, will also offer important information about your heart health.
People experiencing chest pain (angina) or symptoms of heart failure may undergo advanced tests in the office, like ECGs (a test of the heart’s electrical system), stress testing (a test of the heart’s strength) or echocardiograms (an ultrasound of the heart).
The interventional cardiologist is a specialist who often deals with cardiac emergencies, like heart attacks. During a heart attack, the cause is most often due to a blockage in the coronary arteries—blood vessels that supply oxygen to the heart. Interventional cardiologist are trained to do catheterizations. In these non-surgical procedures, a guided wire is inserted into the circulatory system, often through an artery in the groin, and threaded up into the heart to check for the location of the blockage. Using the catheter, an interventional cardiologist can insert a stent—a small tube—that opens up the blocked artery, restoring blood flow to the heart and saving a life in the process.
Interventional cardiologist can also use catheter-based techniques to help treat valve disease and congenital heart disorders.
An electrophysiologist is a cardiologist that primarily deals with disorders of heart rate and rhythm, known as arrhythmias. During an electrophysiology (EP) study, the physician will guide a wire or catheter through the groin into the heart and assess the electrical activity in the heart. Certain medications might be given during an EP study to bring on the abnormal rhythms in a controlled environment, to determine the likely cause of the abnormality. These studies are useful in guiding treatment, to see if a pacemaker, ablation, or surgery is required to treat the arrhythmia.
A cardiac surgeon (sometimes called a cardiothoracic, or CT surgeon) is a specialist who performs heart surgery, such as for severe valve disease or coronary artery disease. For a diseased valve, like in severe aortic stenosis, the cardiac surgeon can replace the valve, restoring proper function. In severe coronary artery disease, surgery can restore blood flow to the heart by creating alternate pathways to “bypass” the clogged arteries in the heart. A cardiac surgeon also performs many other procedures, depending on the needs of the patient—like pacemaker implantation for people with rate and rhythm disorders, and ventricular assist devices placement and transplant surgery for those with severe heart failure.
Whereas cardiac surgeons primarily deal with the heart structure, the vascular surgeon is a specialist who treats diseases of the blood vessels, which are connected to the heart. Diseases of the aorta—the major artery branching off of the heart—, may be treated by vascular surgeons, cardiac surgeons, or both, depending on where the aorta issue is located in relation to the heart.
Vascular surgeons are also experts in helping manage peripheral arterial disease, where cholesterol plaques impede blood flow in the arteries of the extremities, commonly in the foot or legs; venous disease of the extremities, like varicose veins, can also be treated through vascular surgery.
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