As the COVID-19 pandemic ravages a world still grappling with vast uncertainty over the virus, a new and unnerving pattern has emerged in some patients.

Though novel coronavirus symptoms thus far have presented chiefly within the respiratory system, the infection is swiftly showing to be an all-out, system-wide assault that reaches far past the lungs. Doctors in hot spots across the globe have begun to report an unexpected prevalence of blood clotting among COVID cases, in what could pose a perfect storm of potentially fatal risk factors.

In New Orleans, a man in his 30s was admitted to the hospital a week into treatment for the flu, severely sick. Developing shortness of breath, chest pain and an abnormally rapid heart rate -- he was tested for coronavirus -- doctors realized those symptoms also are typical of a pulmonary embolism: a potentially deadly blood clot that can move from the legs to the lungs and damage the heart.

The man's blood work already showed heart damage, though he had no known underlying medical conditions, no recent travel, no recent surgeries. His chest scans, shown first to ABC News, revealed a massive clot. Termed a "saddle embolus" because it hooks over branches of both pulmonary arteries, it was severely stressing the right side of the heart, unable to push blood against the clot already in its strained state.

"Thankfully, we were able to find this and treat this early, otherwise it probably would have killed him," Dr. Siyab Panhwar, a cardiovascular consult for the patient, told ABC News.

PHOTO: An echocardiogram (ultrasound) of the heart of a man in his 30s, tested positive for coronavirus, showing damage to the right side of the heart. (Dr. Siyab Panhwar) More

The patient's system, riddled with inflammation -- increasingly a pattern among patients with COVID-19 -- in such a heightened state may have been doing more harm than good because inflammation -- a defensive mechanism in the body -- can increase clotting.

The body's response creates a domino effect that may cause further harm, doctors told ABC News. Patients' systems are strained by numerous factors triggered by the virus -- stressed lungs, severe inflammation -- that set in motion the clotting effect.

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It's growing so common with severe COVID cases, doctors are recognizing it as a new pattern of clotting called COVID-19-associated coagulopathy, or CAC, which is notably associated with high inflammatory markers in the blood, like D-dimer and fibrinogen.

"This virus is affecting the lungs, but it appears to be causing inflammation of the whole body," Dr. Viren Kaul, a pulmonary critical care specialist at Crouse Health and an assistant professor of medicine at SUNY Upstate Medical University, told ABC News. With those patients at a higher risk of clotting, doctors must identify those individuals a quickly as possible.

In Spain, among the hardest-hit nations, clotting cases have become so prevalent in novel coronavirus patients that doctors have begun routinely treating individuals with therapeutic doses of anticoagulation medication.

"In the beginning of the outbreak, we started only giving them medicine to prevent clots. We saw that it wasn't enough," Dr. Cristina Abad, an anesthesiologist at Hospital Clínicos San Carlos in Madrid, told ABC News. "They started having pulmonary embolisms, so we started [full] anticoagulation on everyone."

Nearly half of the COVID-19 deaths in Spain have been in Madrid.

PHOTO: An echocardiogram (ultrasound) of the heart of a man in his 30s, tested positive for coronavirus, showing damage to the right side of the heart. (Dr. Siyab Panhwar) More

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