Why Is Excessive Blood Clotting Dangerous?

As one gets a cut or wound, the body forms blood clots that help stop bleeding and slow blood loss. Proteins in the blood called fibrins work with small blood cell fragments called platelets, to form the clot. This is called coagulation. After bleeding has stopped and healing has occurred, the clots should be removed by the body. Sometimes blood clots form too easily or do not dissolve properly and travel through the body so as to limit or block blood flow. This is called excessive blood clotting or hypercoagulation. 

Hypercoagulation can be very dangerous. The blood clots formed can travel to the arteries or veins in the brain, heart, kidneys, lungs and limbs. This in turn can cause heart attack, stroke, kidney failure, venous thromboembolism (VTE), peripheral artery disease (PAD), pregnancy-related problems or even death. 

VTE includes deep vein thrombosis (DVT) and pulmonary embolism (PE). PE occurs when a blood clot travels from a deep vein in the body to the lungs. It can damage the lungs and other organs and cause low oxygen levels in the blood. Blood clots formed in a vein deep in the arm or leg can cause deep vein thrombosis (DVT). People with DVT feels pain, and have swelling, redness, or increased warmth in the affected limb. DVT clots can break off, travel to the lungs and cause PE. Peripheral Artery Disease (PAD) is a narrowing of the peripheral arteries, most commonly in the arteries of the pelvis and legs. Blood clots can also cause pregnancy-related problems like miscarriages, stillbirths, preeclampsia, which is high blood pressure that occurs during pregnancy.

The cause of hypercoagulation can be acquired, meaning it is triggered by another disease or condition. Examples include smoking, overweight and obesity, pregnancy, use of birth control pills or hormone replacement therapy, cancer, prolonged bed rest, or car or plane trips. It can also be due to genetic defects, though less common. These genetic defects usually occur in the proteins needed for blood clotting and can also occur with the substances that delay or dissolve blood clots. While these acquired and genetic sources are not related, one can have both.

Excessive blood clotting can be treated with medicines, but sometimes emergency treatment is required. Doctor would examine the size and location of the clots to decide on the kind of treatment needed. Emergency treatment to prevent blood clot that could lead to serious problems like stroke and heart attack involves medicines called thrombolytics or clot busters, which can quickly break up clots. These medicines can cause sudden bleeding, so they are only used to break up large blood clots in life-threatening situations.

In non-emergency situations, blood thinners or anticoagulants are prescribed to keep existing clots from getting bigger and to prevent new clots from forming. Usually, both heparin and warfarin are prescribed at the same time. Heparin is given as an injection or through an IV tube and it acts quickly. Warfarin in pills takes several days before it starts to work. Once the warfarin starts to work, the heparin is stopped.

Would Arthroplasty Raise Heart Attack Risk?

Osteoarthritis (OA), also known as degenerative joint disease, is the most common form of arthritis in the United States. It affects around 13.9 percent of adults aged 25 and older, and 33.6 percent of those over 65. The disease often occurs in the joints of the hand, spine, hips, knees and great toes, and affects the entire joint.

Currently, there is no cure for OA. Noninvasive methods like weight control, physical therapy and medication can mitigate symptoms of most of the OA patients, but patients with severe cases might still need a joint replacement (arthroplasty). Past studies have found around 1.8 million arthroplasty procedures being conducted worldwide every year, the majority of which are total knee and hip replacements.

A paper published online September 23, 2015 in journal ‘Arthritis & Rheumatology’ pointed out that operations to replace a knee or a hip appear to raise heart attack risk in the short term and the risk of blood clots in the long term. Over time, the heart attack risk falls again though blood clot risk is still elevated years later.

Researchers from Boston University School of Medicine studied about 40,000 patients age 50 or older, all with osteoarthritis. 13,849 patients who underwent total knee replacement were compared to 13,849 closely matched people who did not have surgery. Meanwhile, 6,063 patients who had hip replacement surgery were also compared to 6,000 who did not.

Within a month after the operations, there were 35 heart attacks among knee replacement patients, compared to 4 in the control group, and there were 13 heart attacks in the hip replacement group compared to 2 in the control group. Heart attack risk was highest in the first month following surgery and declined over time. The heart attack rates had evened out for both the surgery and control groups 3 years after the operation.

Meanwhile, there were 190 patients with knee replacement and 78 patients with hip surgery developed a type of blood clot called venous thromboembolism, compared to only 3 and 1 in the control group. 5 years later, the likelihood of having a venous thromboembolism were still significantly higher in the surgery groups.

Though exact reasons for higher risk of heart attack are still unclear, the researchers suspected that some biological drivers might play a role, like the effects of anesthesia on the cardiovascular system. Changes in medication for OA patients during the surgical period may also contribute to higher heart attack risk. 

Obviously, the risk of heart attack following arthroplasty might have previously been underestimated. As such, further measures to prevent such serious event might need to be considered.