Info

Vena cava

Right atrium

Aorta

Vena cava

Right atrium

Pulmonary artery

Left ventricle

Right ventricle

Normal heart

Right ventricle

Aorta

Pulmonary artery

Left ventricle

Normal heart

Vena cava

Right atrium

Aorta

Aorta

Vena cava

Right atrium

Aneurysm

Left ventricle

Right ventricle

Heart in Marfan syndrome

Aneurysm

Right ventricle

Heart in Marfan syndrome

Left ventricle

(a) Two years after she led the 1984 U.S. women's volleyball team to a silver medal in the Olympics, Flo Hyman died suddenly when her aorta burst, a symptom of Marfan syndrome. (b) Note the swelling (aneurysm) of the aorta in the heart on the right. A burst aneurysm here is fatal.

Coronary Artery Disease

Dave R., a fifty-two-year-old overweight accountant, had been having occasional chest pains for several months. The mild pain occurred during his usual weekend tennis match, and he attributed it to indigestion. The discomfort almost always diminished after the game, but recently the pain seemed more severe and prolonged. Dave asked his physician about the problem.

The physician explained that Dave was probably experiencing angina pectoris, a symptom of coronary artery disease (CAD), and suggested that he undergo an exercise stress test. Dave walked on a treadmill, increasing speed and incline while he exercised, and an ECG was recorded, and his blood pressure monitored. Near the end of the test, when Dave's heart reached the desired rate, a small quantity of radioactive thallium-201 was injected into a vein. A scintillation counter scanned Dave's heart to determine if branches of his coronary arteries carried the blood marked with the thallium uniformly throughout the myocardium (see fig. 15.12).

The test revealed that Dave was developing CAD. In addition, he had hypertension and high blood cholesterol. The physician advised Dave to stop smoking; to reduce his intake of foods high in saturated fats, cholesterol, and sodium; and to exercise regularly. He was given medications to lower his blood pressure and to relieve the pain of angina. The doctor also cautioned Dave to avoid stressful situations and to lose weight.

Six months later, in spite of following medical advice, Dave suffered a heart attack — a sign that blood flow to part of his myocardium had been obstructed, producing oxygen deficiency (ischemia). The attack began as severe, crushing chest pain, shortness of breath, and sweating. Paramedics stabilized Dave's condition and transported him to a hospital. There, a cardiologist concluded from an ECG that Dave's heart attack was caused by a blood clot obstructing a coronary artery (occlusive coronary thrombosis). The cardiologist administered a "clot-busting" (thrombolytic) drug, tissue plasminogen activator (t-PA) intravenously.

After some time, the ECG showed that the blood vessel remained partially obstructed, so the cardiologist ordered a coronary angiogram. In this X-ray procedure, which was conducted in the cardiac catheterization laboratory, a thin plastic catheter was passed through a guiding sheath inserted into the femoral artery of Dave's right inguinal area. From there, the catheter was pushed into the aorta until it reached the region of the opening to the left coronary artery, and then near the opening to the right coronary artery.

X-ray fluoroscopy monitored the progress of the catheter. Each time the catheter was in proper position, a ra-diopaque dye (contrast medium) was released from its distal end into the blood. X-ray images that revealed the path of the dye as it entered a coronary artery and its branches were recorded on videotape and on motion picture film, which were later analyzed frame by frame. A single severe narrowing was discovered near the origin of Dave's left anterior descending artery. The cardiologist decided to perform percutaneous transluminal coronary angioplasty (PTCA) in order to enlarge the opening (lumen) of that vessel.

The PTCA was performed by passing another plastic catheter through the guiding sheath used for the angiogram. This second tube had a tiny deflated balloon at its tip, and when the balloon was located in the region of the arterial narrowing, it was inflated for a short time with relatively high pressure. The inflating balloon compressed the atherosclerotic plaque (atheroma) that was obstructing the arterial wall. The expanding balloon also stretched the blood vessel wall, thus widening its lumen (re-canalization). Blood flow to the myocardial tissue downstream from the obstruction improved immediately.

About 50% of the time, a vessel opened with PTCA becomes occluded again, because the underlying disease persists. To prevent this restenosis, the doctor inserted a coronary stent, which is an expandable tube or coil that holds the vessel wall open. The cardiologist had two other options that have a slightly higher risk of causing damage. She might have vaporized the plaque obstructing the vessel with an ex-cimer laser pulse delivered along optical fibers threaded through the catheter. Or, she could have performed atherectomy, in which a cutting device attached to the balloon inserted into the catheter spins, removing plaque by withdrawing it on the catheter tip.

Should the coronary stent fail, or an obstruction block another heart vessel, Dave might benefit from coronary bypass surgery. A portion of his internal mammary artery inside his chest wall would be removed and stitched between the aorta and the blocked coronary artery at a point beyond the obstruction, restoring circulation through the heart. ■

Shier-Butler-Lewis: Human Anatomy and Physiology, Ninth Edition

IV. Transport

1B. Cardiovascular System

© The McGraw-Hill Companies, 2001

Cardiovascular System

Cardiovascular System

Integumentary System Lymphatic System

Cardiovascular System

The heart pumps blood through as many as 60,000 miles of blood vessels delivering nutrients to, and removing wastes from, all body cells.

Changes in skin blood flow are important in temperature control.

Changes in skin blood flow are important in temperature control.

Skeletal System

Bones help control plasma calcium levels.

Bones help control plasma calcium levels.

Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

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