Heart Anatomy

How the heart works

The heart is a muscular pump about the size of your fist. It sits between the lungs in the middle of the chest. It has four chambers. The two upper chambers, the atria, receive blood. The two lower chambers, the ventricles, pump it out. The right side sends oxygen poor blood to the lungs. The left side pumps oxygen rich blood to the whole body. Four valves keep blood moving in one direction. They snap shut to stop it flowing backward. The heart muscle feeds itself through the coronary arteries, which wrap around the outside. An electrical system sets the pace. It starts at the sinus node and spreads through the muscle, so the chambers squeeze in order. A healthy adult heart beats roughly 60 to 100 times a minute at rest. That range is described by the National Heart, Lung, and Blood Institute.

The four chambers and four valves

Blood returning from the body enters the right atrium. It passes through the tricuspid valve into the right ventricle. It then leaves through the pulmonary valve to the lungs. Oxygenated blood returns to the left atrium. It crosses the mitral valve into the left ventricle. It exits through the aortic valve into the aorta. The left ventricle is the thickest chamber because it does the hardest work.

Valves fail in two ways. They can stiffen and fail to open fully, called stenosis. They can leak and let blood wash backward, called regurgitation. Either creates turbulence. A stethoscope picks that turbulence up as a heart murmur. The American Heart Association notes that valve problems are often silent for years before symptoms appear.

The coronary arteries and the electrical system

Two main coronary arteries branch off the aorta. They divide across the heart's surface. Plaque can narrow them. The muscle then runs short of oxygen during exertion. That is coronary artery disease, and it is the reason for exertional chest pain.

The electrical system is separate. The signal starts in the sinus node. It pauses at the AV node, then spreads to the ventricles. Interruptions anywhere along that path produce arrhythmias. These include atrial fibrillation from the upper chambers and ventricular arrhythmias from the lower ones.

Symptoms to watch for

Knowing the anatomy makes symptoms easier to interpret. Call the office if you notice chest tightness with exertion, breathlessness climbing stairs, ankle swelling, palpitations, or fatigue that is new for you.

Call 911 for chest pressure lasting more than a few minutes, chest discomfort with sweating or nausea, pain radiating to the arm or jaw, fainting, or sudden severe shortness of breath. Face drooping, arm weakness or slurred speech are stroke signs and also require 911.

How Dr. Nanavati diagnoses heart problems

Each structure has a test that examines it directly.

• Echocardiogram and transthoracic echocardiography use ultrasound to show the chambers and the valves. They also give the ejection fraction, the percentage of blood the left ventricle pushes out with each beat.
• Transesophageal echocardiography provides a closer view of the valves and upper chambers. It is used when a standard study is limited.
• Electrocardiogram (ECG or EKG) maps the electrical system in about ten seconds.
• Holter monitoring records the rhythm continuously for a day or two.
• Treadmill stress testing and nuclear stress testing show whether the coronary arteries deliver enough blood under load.
• Coronary CT angiography images the coronary arteries themselves.
• Vascular ultrasound and carotid ultrasound Doppler examine the arteries beyond the heart.

Echocardiography, ECG, stress testing and vascular ultrasound are all performed in the office. The complete list of cardiology services shows what is available.

Treatment options

Treatment is matched to the part of the heart that is affected. Narrowed coronary arteries are treated with cholesterol and blood pressure medication. When needed, an affiliated hospital adds angioplasty and coronary stenting. Electrical problems are treated with rate control medication, ablation, or a pacemaker. That device is checked by pacemaker interrogation. Valve disease is monitored with serial echocardiograms. It is referred for repair or replacement when it becomes severe. Weak pumping is treated with medications that protect and unload the heart muscle. Underlying all of it is prevention. That work is guided by heart healthy living plus advanced lipid testing. Cardiac rehabilitation helps after an event.

What to expect at your visit

Bring your medication list, recent labs and any prior heart test reports. Your appointment includes a history and an exam. Dr. Nanavati places the stethoscope on several spots to hear each valve. The visit also includes blood pressure and an ECG. If an echocardiogram is ordered, expect to lie on your side. A technologist takes images for about half an hour. Dr. Nanavati will show you what the pictures mean using your own anatomy. You can review other patient education videos or read the FAQs page beforehand.

When to see a cardiologist

See a cardiologist if you have a murmur, an abnormal ECG, exertional breathlessness or palpitations. A family history of early heart disease is another reason. Screening also makes sense if you have high blood pressure, high cholesterol or diabetes. Request an appointment online or call the Bonita office at (619) 585-0476.

Dr. Vimal Nanavati, MD, FACC is board certified in cardiology and interventional cardiology. He has 32 years of experience. He founded Advanced Heart Care, Inc. in 1997. He sees patients at three locations. The Bonita office is in South San Diego. It serves Chula Vista, Eastlake, Otay Ranch, National City, Spring Valley, Imperial Beach, San Ysidro and Coronado. The North San Diego office at 5190 Governor Dr serves University City, La Jolla, Clairemont and Mira Mesa. The Redding office serves Shasta County, Anderson, Red Bluff, Palo Cedro and Cottonwood.

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