What Causes a Heart Attack?

Most heart attacks occur as a result of coronary artery disease (CAD). CAD is the buildup over time of a material called plaque on the inner walls of the coronary arteries. Eventually, a section of plaque can break open, causing a blood clot to form at the site. A heart attack occurs if the clot becomes large enough to cut off most or all of the blood flow through the artery.

Coronary Artery With Plaque Buildup

The illustration shows a normal artery with normal blood flow (figure A) and an artery containing plaque buildup (figure B).

The blocked blood flow prevents oxygen-rich blood from reaching the part of the heart muscle fed by the artery. The lack of oxygen damages the heart muscle. If the blockage isn’t treated quickly, the damaged heart muscle begins to die.

Heart attack also can occur due to problems with the very small, microscopic blood vessels of the heart. This condition is called microvascular disease. It’s believed to be more common in women than in men.

Another less common cause of heart attack is a severe spasm (tightening) of a coronary artery that cuts off blood flow through the artery. These spasms can occur in coronary arteries that don’t have CAD. It’s not always clear what causes a coronary artery spasm, but sometimes it can be related to:

• Taking certain drugs, such as cocaine
• Emotional stress or pain
• Exposure to extreme cold
• Cigarette smoking

The animation below shows how a heart attack occurs. Click the “start” button to play the animation. Written and spoken explanations are provided with each frame. Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames.

The animation shows how blood flow is blocked in the heart, leading to a heart attack.

Other Names Who Is At Risk

CAuses of Skin Cancer

Exposure to the sun's ultraviolet (UV) rays appears to be the most important factor in the development of skin cancer.

The overall level of UV light reaching the Earth's surface is increasing because our planet's atmospheric ozone layer, which filters out much of the UV radiation, is thinning over certain parts of the globe. "The greatest hazard humans face from the effects of ozone depletion is skin cancer," according to the Skin Cancer Foundation, a nonprofit group that raises research funds and educates the public and medical community about skin cancer.

The beach, pool-side and golf course are not the only places where you need sun protection. UV radiation can pierce your car window and damage your skin as you drive. Sun exposure also can damage facial skin in winter when you go skiing or sledding, and accelerate the skin's aging process with premature dryness and wrinkles. Development of sun-induced skin cancer is a very slow process. Research suggests that long-term exposure to UV radiation raises your skin cancer risk visibly through sunburn and invisibly by damaging the DNA in skin cells.

While nearly 90 percent of all skin cancers are thought to stem from the sun's UV radiation. Other factors also make skin cancer more likely, according to the American Cancer Society. They include:

Fair complexion: Having light skin, skin that freckles or burns easily and blue eyes increases your risk of skin cancer.

Moles: Irregularly shaped or colored moles and having lots of moles may increase your risk of melanoma.

Chemical exposure: Exposure to arsenic, a heavy metal used in making some insecticides, and found in some water supply, increases the risk of developing non-melanoma skin cancer. Occupational exposure to industrial tar, coal, paraffin and certain types of oil also may increase the non-melanoma skin cancer risk.

Radiation exposure: Radiation therapy may increase the risk of a non-melanoma skin cancer.

Long-term or severe skin inflammation or injury: In rare cases, non-melanoma skin cancers grow in scars from severe burns, on areas of skin over severe bone infections, and on skin damaged by certain severe inflammatory skin diseases.

Psoriasis treatment: Patients treated with the drug psoralen and ultraviolet light (PUVA) may have an elevated risk of squamous cell carcinoma.

Actinic keratosis: These thick scaly patches of skin can sometimes develop into cancer.

Xeroderma pigmentosum: This very rare hereditary disease makes it difficult for the skin to repair DNA damage from UV light. Xeroderma pigmentosum patients typically suffer many skin cancers, which may begin in childhood.

Basal cell nevus syndrome: People born with this rare condition develop multiple basal cell carcinomas and other health problems.

Reduced immunity: People whose immune system is diminished because of HIV infection, drugs that prevent rejection of donor organs or chemotherapy are at increased risk for non-melanoma skin cancer. New immune drugs used to treat skin disease may affect the body's immune system and increase the risk of cancer, especially lymphomas.

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Causes of abnormal vaginal discharge.

Lactobacilli are common in the human body. They aid digestion in the gastrointestinal tract and help prevent infection in the vagina. The lactobacilli found in the vagina produce lactic acid which maintains a level of acidity that provides a good defense against infection. But when this level is disrupted infection can set in.

The causes of abnormal vaginal discharge can be either infectious or non-infectious:
Infectious causes include:

• Bacterial vaginosis
• Vaginal candidiasis (yeast infection)
• Cervico-vaginitis resulting from a sexually transmitted infection (STI)
  • Trichomonas
  • Gonorrhea and chlamydia

Non-infectious causes:

• Use of perfumes, soaps, or latex on or around the vagina
• Contact dermatitis - a skin reaction resulting from exposure to allergens or irritants
• Atrophic vaginitis - inflammation of the vagina due to the thinning and shrinking of the tissues, as well as decreased lubrication.
• Excessive vaginal secretions

Prevention

• Always practice safe sex. Wear a condom to protect yourself from HIV, syphilis, gonorrhea, and other STIs.
• Form good hygeine habits. Wipe from front to back, avoid vaginal douching. Avoid certain sexual activities that may also contribute to vaginal infections.
• If you suffer from vaginal irritation easily, try to avoid scented sanitary napkins and toilet paper, soap, shampoo, bubble bath, tight undergarments made of synthetic fibres or latex, etc. This may reduce your chances of infection.
• Good health habits, such as exercise, weight loss, not eating refined sugar, and better stress management, are helpful.