Heart Surgery in CAD Patients Can Be Performed Safely with Certain Adjustments, Study Indicates

Heart surgery can be performed safely in people with cold agglutinin disease (CAD) by adopting a series of procedure adjustments, according to a case study.

The study, “Cardiopulmonary bypass strategy in a patient with cold agglutinin of high thermal amplitude,” was published in the journal Artificial Organs.

CAD is a form of autoimmune hemolytic anemia (AIHA), in which antibodies called cold agglutinins attack and destroy red blood cells at low body temperatures.

The disease can lead to several complications in patients who need to undergo heart surgery, especially when the interval between their body temperature and the maximum temperature at which cold agglutinins bind to red blood cells — a parameter known as thermal amplitude (TA) — is very large.

Physicians in China described the case of a patient with CAD and high TA, who underwent successful heart surgery.

The 67-year-old man was diagnosed with severe aortic regurgitation — when one of the heart’s valves does not close properly, allowing some of the blood pumped out to leak back into the heart — that required surgical replacement of the valve.

Pre-operative tests showed that the patient’s red blood cells clumped at room temperature, and further tests indicated he had a TA of 32 C (approximately 90 F), confirming the diagnosis of CAD.

Physicians replaced the faulty aortic valve through cardiopulmonary bypass (CPB), a surgical technique in which one’s bloodstream is connected to a machine that serves as a reservoir and pumps oxygenated blood back while surgeons operate safely on the heart. CBP can be performed after lowering the body temperature to around 28 C (approximately 82 F), or while maintaining normal body temperature (35–37 C; 95–99 F).

The main reason why surgeons lower a patient’s body temperature during CBP (hypothermic CBP) is to protect organs from damage during the procedure, while reducing metabolic rates and suppressing the production of toxic free radicals.

In this case, physicians decided to maintain the patient at normal body temperature during surgery.

Once CBP was finished, physicians started administering a warm solution of oxygenated blood and potassium every 20 minutes to reduce heat loss and protect the heart’s muscle from damage.

The team did not observe red blood cell clumping — neither in the circuit they used to divert deviate blood from the heart, nor in the patient’s coronary arteries.

A transesophageal echocardiography — a test that allows visualization of the heart while it is pumping blood — performed after surgery revealed that the patient’s ventricles (the heart’s lower chambers) were moving normally.

Further lab tests also confirmed that his levels of liver enzymes and bilirubin were normal, as was his kidney function.

The patient did not require transfusion of red blood cells following surgery, and was discharged from the hospital 10 days later.

“Cardiac surgery in patients with cold agglutinins of high TA is a big challenge,” the researchers wrote. “The principle is to keep nadir [lowest] blood temperature above TA,” they added, while using additional strategies to protect the heart’s muscle from being damaged and prevent clumping of red blood cells.