CAD diagnosed during emergency heart surgery in woman

Case report indicates warm blood cardioplegia may be needed for CAD patients

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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The induced reduction in body temperature during an emergency surgery to replace a damaged heart component revealed the presence of mild cold agglutinin disease (CAD) in a woman in India, a study reports.

The case study, “Cardiopulmonary Bypass Surgery-Cold Alert!,” was published in Annals of Cardiac Anaesthesia.

In CAD, the immune system wrongly produces cold agglutinins, a type of self-reactive antibody that binds to red blood cells in cold temperatures. When this happens, the red blood cells form clumps that are destroyed by the immune system.

This results in anemia, or a below normal number of red blood cells, which may affect oxygen transport throughout the body. Other symptoms include a bluish discoloration of the skin (acrocyanosis) and Raynaud’s phenomenon, which causes fingers and toes to feel numb in response to cold.

Cold agglutinins “are often found in the [blood] of healthy individuals” at “clinically harmless titers [levels],” the researchers wrote, but their ability to cause disease is typically associated with their presence at high levels and their activation over a large temperature range, which can include 30-plus C (about 86-plus F).

In cases of so-called benign CAD, cold agglutinins typically bind to red blood cells at temperatures below 15 C (about 59 F), meaning “some patients remain asymptomatic until exposed to cold temperatures,” wrote a team of researchers in India who described the case of a 45-year-old woman who presented signs of CAD during an emergency heart surgery.

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The woman was scheduled for a balloon mitral valvotomy, a procedure wherein a narrowed mitral valve is opened to help the heart work better.

The heart has four mitral valves, or pairs of flaps that keep blood flowing in the right direction with each heartbeat. When a mitral valve doesn’t open well, the amount of blood that flows from the heart may decrease.

Blood work showed the woman had slightly lower levels of hemoglobin, the protein in red blood cells that transports oxygen, and slightly higher levels of bilirubin, a marker of red blood cell destruction.

During surgery, one of the mitral valve’s flaps ruptured and the woman was prepared for an emergency surgery to replace it.

Her body was cooled to 28 C (82.4 F) to slow down all its processes and help protect her organs during surgery. To allow the surgeon to perform the procedure, a cold solution (4 C or 39.2 F) of cardioplegia, a chemical that induces a rapid heart stop, was injected into her heart.

At the same time, her blood was circulated through a machine called a cardiopulmonary bypass, which acts as a replacement for the heart and the lungs during surgery.

After a few minutes, her blood began to clump in the cardioplegia tube. Based on this observation, the doctors made a diagnosis of CAD, which was later confirmed by the presence of cold agglutinins on blood tests.

To prevent further blood clumping and associated complications, the woman’s body was slowly warmed to 34 C (93.2 F), after which the clumps dissolved and the next cardioplegia dose was warmed.

The woman had no signs of acrocyanosis or other organ complications and no signs of blood in her urine.

Before being weaned off the cardiopulmonary bypass, her heart’s blood vessels were flushed with warm blood. Then her body was kept at 37 C (98.6 F) “with a warming blanket, air warmer, and fluid warmer,” the researchers wrote.

After surgery, her hemoglobin levels were still slightly lower than normal, with a reduction in bilirubin levels.

“She was discharged without any [kidney], neurological, or myocardial [heart muscle] injury,” the researchers wrote. “We assume that the patient had benign [CAD] and her thermal threshold was higher than 28°C as the blood in the [cardiopulmonary] bypass machine had no clumps.”

Apart from red blood cell destruction, “other complications are less likely and patients with [CAD] can safely undergo bypass at normal body temperature or temperatures more than the thermal threshold,” they said. “Warm blood cardioplegia may be the choice of myocardial protection in these patients.”