Learn About Your Heart...
Made Simple


By Nicolas Shammas, MD


A new, comprehensive sourcebook for
heart and vascular disease patients

Cardiovascular Health Topics



1.
Statistics about Heart and Blood Vessel Diseases in the United States
2.
Structure and Function of the Heart and Blood Vessels
3.
Diseases of the Blood Vessels of the Heart
4.
Surgical Therapies for the Cardiovascular Patient
5.
Peripheral Vascular Disease
6.
Diseases of the Blood Vessels of the Head and Neck
7.
Strokes: How to Survive Them and How to Prevent Them
8.
Valvular Heart Disease
9.
Heart Rhythms: How to Recognize Them and Treat Them
10.
Congestive Heart Failure
11. Understanding Cardiomyopathy, or Weak Heart Muscle
12. Children and Heart Disease
13. Diseases of the Pericardium
14. Systemic Illnesses, Infections and Drugs that Affect the Heart
15. Erectile Dysfunction: a Vascular Disease
16. Cardiovascular Disease Prevention
17. Heart Healthy Nutritional Tips
18. Cardiac Rehabilitation
19. Medications for Cardiovascular Disorders
20. Heart Tests You Need to Know
21. Learn What to Do in a Medical Emergency
22. How to Choose Your Doctor and Hospital
23. Medical Research and How You Can Get Involved
24. Taking the Next Step — A Few Community Resources to Help You Live More Healthfully
25. How Much Did You Learn from This Book: Take a Simple Test

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Figure 2.


Figure 3.

STRUCTURE AND FUNCTION OF THE HEART AND BLOOD VESSELS

Nicolas W. Shammas, MS, MD, FACC, FACP

What is the function of the heart?

The heart is a pump that distributes blood to the organs of the body. The heart is made of 4 chambers. The top 2 collecting chambers are called atria; the bottom 2 ejecting chambers are called ventricles (see Figure 1).

The right atrium receives blood deficient in oxygen from the body and sends it into the right ventricle. The right ventricle squeezes the blood out to the lungs to pick up fresh oxygen.The oxygenated blood returns from the lungs to the left atrium, which then funnels the blood into the left ventricle. The left ventricle ejects the oxygenated blood into the entire body via the aorta.

What is the aorta?

The aorta is the major blood vessel that comes out of the heart and distributes oxygenated blood to the rest of the body including the heart itself (see Figure 2). Blood vessels coming out of

the aorta and supplying blood to the heart are called coronary arteries.The aorta supplies blood to the head via the carotid and vertebral arteries. Major branches coming out of the aorta also include the renal arteries (supplying blood to the kidneys), the mesenteric arteries (supplying blood to the gut), the celiac artery (supplying blood to the liver and spleen), and the iliac arteries (supplying blood to the hip and lower legs). Diseases that affect the aorta and its branches are numerous but most commonly include cholesterol buildup with subsequent blockages, stretching and dilatation, called aneurysms, or tears, called dissections.

What are the major components of the heart?

The heart is made of a contracting muscle that generates the force required to transport blood to all parts of the body. The muscle contracts from the bottom up to eject the blood into the aorta. The aorta branches out into a network of blood vessels that distributes blood to the organs of the body.

In the heart, there are 4 valves that allow the blood to move in 1 direction only. For example, the aortic valve opens when the ventricle contracts and closes immediately when the heart relaxes, preventing the blood from returning back to the left ventricle.

In addition to the muscle and the valves, the heart is made of a complex electrical system that allows the muscle to pump continuously and predictably. Electrical impulses are generated from a site in the right atrium called the sino-atrial node. This serves as the natural pacemaker of the heart, generating electrical impulses at the normal resting rate of 60 to 100 beats per minute. At a rate of 60 beats per minute, the heart contracts approximately 31,536,000 beats per year.

Describe the heart valves and their function

The 4 valves in the heart that allow blood to move only in 1 direction are the aortic, mitral, tricuspid, and pulmonic valves (see Figure 3). The aortic and pulmonic valves, when open, allow the blood to leave the heart and, when closed, prevent the blood from returning to the heart. The mitral and tricuspid valves, when open, allow the blood to move from the atria to the ventricles and, when closed, prevent the blood from moving backward into the atria. A leak in a valve indicates that the valve does not close well (regurgitant valve), allowing blood to move back-ward through it. A narrowed valve (stenotic) does not allow adequate blood to go through it when opened.

Endocarditis, an infection of the valves, can occur in patients with damaged or structurally abnormal valves. Endocarditis can damage the valves and is a condition that requires aggressive antibiotic therapy and occasionally urgent valve surgery.

What are heart sounds and murmurs?

Heart sounds are generated from the closure of the valves. There are 2 normal heart sounds. One is generated from closure of the mitral and tricuspid valves when the heart contracts and is called S1. The second heart sound is generated from the closure of the aortic and pulmonic valves when the heart relaxes and is called S2.

Abnormal heart sounds can be generated in the setting of heart failure (S3) or from a very stiff ventricle, such as in the setting of long-standing high blood pressure or heart attacks (S4).

Heart murmurs can range from normal (or physiologic) in the setting of normal valvular function to abnormal (or pathologic), such as in the setting of a severe leak (regurgitation) or narrowing (stenosis) in the valves. When a valve is narrowed, the blood ejected through it generates a high velocity jet and turbulence, which causes the murmur. Also, if a valve leaks, a high jet of blood flows through the leaky valve, generating a murmur. Murmurs have various characteristics and generally can tell a physician a lot of information about the function of the valves of the heart.

Heart sounds and murmurs are heard with a stethoscope placed over the heart, a process called auscultation.

What are the arteries?

The heart pumps blood into the blood vessels, a series of pipes that take blood from the heart to the organs of the body (via the arteries) and send the blood back into the heart (via the veins). The arteries are muscular and elastic (like a rubber band) and are able to send the blood in a pulsatile form to all organs. As the arteries enter an organ, they branch and narrow significantly to reach all parts of this organ. Arteries expand as they receive blood from the heart and recoil back like a rubber band to aid in pushing the blood forward to the organs. Arteries carry oxygenated blood to all the organs except the lung. The pulmonary artery arises from the right ventricle and carries blood deficient in oxygen into the lung.


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