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Cardiorenal syndrome

On the first Friday of every month I give a lecture to the residents at St. John Hospital and Medical Center. I like to do an electrolyte lecture but for March the chief resident asked me to talk about cardiorenal syndrome. In researching the lecture I came across this article by Claudio Ronco.

The article defines cardiorenal syndrome as any condition with simultaneous kidney and heart failure. He then goes on to subdivide cardiorenal syndrome into 5 types:

  1. Acute heart failure causing acute renal failure
  2. Chronic heart failure causing chronic kidney disease
  3. Acute kidney injury causing any type of acute cardiac dysfunction (including arrhythmia)
  4. Chronic kidney disease causing any chronic cardiac disease
  5. Any systemic condition that causes renal and cardiac dysfuction (e.g. sepsis)

This is terrible. Cardiorenal syndrome used to signify the unique cause of acute kidney injury where the decrease in function is due to apparent volume depletion in a patient that obviously overloaded. It named the only scenario where acute kidney injury responded to diuresis. It was unique and specific. Ronco comes along and says, yes I like your version of cardiorenal syndrome so I will make it type 1 in my new all purpose definition of cardiorenal syndrome. Now whenever there is cardiac dysfunction and simultaneous kidney dysfunction we can just call it cardiorenal syndrome.

It doesn’t have to be this way look at the example of hepatorenal syndrome. The syndrome does not refere to just any situation with simultaneous renal and liver dysfunction. It is a very specific diagnosis that only occurs with chronic liver disease and ascites. The patients must be oliguric, there is no non-oliguric HRS. Patients must be sodium avid and unresponsive to fluids and albumin. Additionally the patients cannot have laboratory or imaging evidence for an alternative cause of renal failure. Because of this definition hepatorenal syndrome identifies a very specific disorder, with a specific pathophysiology and unique prognosis and treatment options.

Ronco takes the beautiful and evocative name cardiorenal syndrome, strips it of all specificity and then tries to restore it by tacking on five different types. The fifth type 5 is the one that makes my brain explode. Sepsis, really? Acute kidney injury from sepsis that happens in the same patient who also suffers from sepsis induced cardiomyopathy should now be considered to have cardiorenal syndrome? Ronco is a man who has spent his life studying sepsis and acute renal failure, I can’t believe he is actually referring to that condition as CRS type 5.

I’m not buying what Ronco’s selling. Cardiorenal syndrome begins and ends with type 1 for me.

FYI: Here is the lecture (Keynote, PDF). It still needs some work. I’d like to add a section on ultrafiltration and I need to include the NEJM article on furosemide that was published yesterday.

6 Replies to “Cardiorenal syndrome”

  1. Hello,
    I am a nephrologist and completed fellowship in NY recently.
    Good post and thanks for sharing. I saw your post on FB. I think Ronco is trying to emphasize the mutual interaction between the two organs, which is absent between liver and Kidney. I don't think kidney disease can in any way cause liver disease. But I agree with you that Cardiorenal syndrome has to be fairly specific especially for purposes of research.
    however, I would include both 1, 2 and 4. instead of just one, since the mechanisms in 1, 2 are same and 4 highlights the effects Kidney disease can have on the heart. the treatments for all of these have major overlaps too

  2. Thanks for the comment.

    Patients with chronic compensated heart failure leading to progressive CKD (Type 2 CRS) I see as very different from type 1 CRS. These are patients, if I understand Ronco correctly, that require aggressive RAAS inhibition and diuresis to remain in compensated CHF. These are not patoients who would do better with increased diuresis or increased RAAS inhibition, as is seen in CRS type 1. So in my eyes this is a unique mechanism from type 1 and its therapy is also unique.

    Chronic renal failure leading chronic heart disease. In this situation a dialysis patient who develops left ventricular hypertrophy could be said to be suffering from cardiorenal syndrome. This doesn't pass the smell test and certainly is not a situation that would respond to the same therapeutics as CRS type 1.

  3. I like this part of your comment a lot:

    emphasize the mutual interaction between the two organs, which is absent between liver and Kidney. I don't think kidney disease can in any way cause liver disease

    thanks

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