Undergoing surgery to correct a cardiac problem may cause a temporary decline in kidney function or worsen an existing kidney issue. Dialysis and kidney transplant are the primary treatment options.

Your heart and kidneys rely on each other to function. When your heart is compromised by coronary artery disease, a heart valve disorder, or heart failure, your kidneys may be affected, too.

Even when heart surgery is done to correct a problem, the risk of kidney failure or temporary injury to kidney function is still possible.

Doctors know the risk factors for kidney failure following heart surgery and how to lower that risk or treat kidney problems afterward. If you are scheduled for heart surgery, it’s important to understand how the procedure may affect your kidney health and what to expect during your recovery.

A 2021 study suggests that kidney failure is a major complication associated with several types of cardiac surgery. According to the study, aortic valve surgery was particularly problematic.

However, researchers also noted that while kidney complications may be more common when they stem from aortic valve surgery, they also tend to have better short- and long-term outcomes.

When a person’s heart health reaches a point when surgery is necessary, the kidneys are likely already feeling the strain.

Poor heart function can cause blood to back up in the kidneys’ veins, affecting their ability to filter wastes and toxins from your blood. Poor circulation can also keep your kidneys from receiving sufficient supplies of oxygen-rich blood.

A 2016 study suggests that kidney problems tend to follow heart surgery either due to preexisting health problems, such as diabetes and high blood pressure, or due to complications related to the surgical procedure or postoperative recovery in the intensive care unit (ICU).

For example, a 2022 study notes that the kidneys may experience a greater burden and potential injury the longer a person is connected to a cardiopulmonary bypass machine before, during, and immediately after surgery.

A 2023 report on kidney injury related to cardiac surgery notes that low blood pressure (hypotension) and reduced blood flow from the heart (cardiogenic shock) are common complications. The reduced circulation in the kidneys from these complications can cause them to fail.

Not surprisingly, having kidney issues before your heart surgery raises the risk of postoperative kidney complications.

But other risk factors may increase the chances of kidneys failing after heart surgery. A 2021 study identified several key factors, including:

  • advanced age
  • female sex
  • preexisting heart problems, kidney problems, or both

Surgeries that are especially complex or done on an emergency basis also raise the risk of kidney failure following heart surgery.

Strategies for preventing postoperative kidney dysfunction

A 2021 study suggests several strategies that may help prevent or lower the risk of kidney injury after heart surgery. These include:

  • corticosteroids to reduce inflammation and ease the workload of the kidneys
  • delaying heart surgery for 24 to 72 hours after the use of contrast dye for imaging, because contrast agents can sometimes cause kidney problems as they are flushed from the body
  • greater attention to hemodynamics, which is the measure of cardiac output, arterial pressure, and other heart-related functions

There are two main treatments for kidney failure after heart surgery: dialysis and kidney transplant. This is also true for kidney failure that develops without cardiac surgery.

Dialysis is a machine-assisted treatment that helps the body remove waste material and toxins from the blood when the kidneys can no longer do a sufficient job.

The frequency and duration of dialysis treatments depend on the severity of kidney disease. As your heart function and overall health improve after surgery, it’s possible you may be able to stop dialysis or have treatments less often.

However, it’s important to know that kidney failure has no cure. Medical treatments and lifestyle strategies, however, can slow disease progression and, in some cases, reverse some damage.

A kidney transplant can offer a person with kidney failure greater health and a longer life. Kidneys are donated from recently deceased donors or living donors.

The outlook for someone who experiences kidney failure following heart surgery depends on several factors, including the person’s age and overall health.

The American Kidney Fund suggests that with dialysis, a person with kidney failure may live another 5 to 10 years.

A kidney transplant could extend a person’s life another 10 to 20 years, depending on whether the kidney is from a deceased or living donor.

Serious kidney injury affects about 30% of people who have heart surgery, though many of these people are already at risk of kidney problems before their procedures.

If you are scheduled for cardiac surgery, talk with your doctor about all the potential complications, including kidney failure.

Feel free to ask what precautions your surgery team will take before and during the operation, and what can be done to minimize kidney problems during your recovery.