Cardiorenal syndrome is a disorder of the kidneys or the heart where an acute or long term dysfunction in one of these organs may cause an acute or long-term dysfunction of the other. This condition is normally characterized by the triad of concomitant decreased function of the kidney.
The human kidneys and heart are responsible for maintaining the organ perfusion and hemodynamic balance via a complex network. These two organs exchange information with one another and they are dependent on each other.
Cardiorenal Syndrome results from simultaneous abnormalities of the heart and kidney.1 The disease of the heart or kidney in few cases affect normal kidney or heart respectively resulting in abnormalities. The heart and kidneys are linked together and communicate with each other through various pathways. In this article, we will discuss in detail the various aspects of Cardiorenal Syndrome.
How is Cardiorenal Syndrome Defined?
- Cardio-renal Syndrome- This Syndrome is caused by dysfunctions of the heart and kidneys.
- Cardiac Disease Causes Renal Dysfunction2– Cardiac disease such as congestive heart failure or myocardial infarction results in lower kidney blood flow. The low kidney blood flow initiates kidney diseases
- Effects of Cardiac or Kidney Dysfunction- Acute or chronic diseases of one organ leads to a dysfunction of the other organ.
- Hemodynamic Instability- Heart and kidneys maintain hemodynamic stability and supply oxygenated blood to entire body.
Causes of Cardiorenal Syndrome
Cardiorenal syndrome may be caused by chronic kidney disease. It can also be caused by comorbid conditions like anemia, hypertension that cannot be controlled and diabetes mellitus. Some medications like ACE inhibitors receptor blockers, NSAIDS, diuretics and aldosterone receptor antagonists can also cause cardiorenal syndrome.
Classification of Cardiorenal Syndrome
There are Three Types of Cardiorenal Syndrome-
Type 1 or Acute Cardiorenal Syndrome:
- In this type of Cardiorenal syndrome, there is sudden worsening of cardiac function along with kidney injury.
- Some of the examples of this type of Cardiorenal Syndrome is acute cardiogenic shock or heart failure
Type 2 or Chronic Cardiorenal Syndrome:
- In this type of Cardiorenal syndrome, there are chronic disorders of cardiac function resulting in progressive chronic kidney disease.
- An example of this type of Cardiorenal Syndrome is chronic heart failure.
Type 3 or Secondary Cardiorenal Syndrome:
- In this type of Cardiorenal syndrome, there are both cardiac as well as renal dysfunctions.
- Examples are diabetes mellitus, sepsis, or lupus.
Effects of Cardiorenal Syndrome
Cardio-Renal Syndrome is Attributed to Following Physiological Abnormalities:
- Low cardiac output.
- Increased intraabdominal and central venous pressures.
- Decreased kidney blood flow.
- Gradual worsening of renal function.
Risk Factors of Cardiorenal Syndrome
- Cardiorenal syndrome is mostly often seen in older age
- Dehydration is also a risk factor for Cardiorenal syndrome
Pre-Existing Cardiac Diseases as a Risk Factor for Cardiorenal Syndrome
- Congestive heart failure is a risk factor for Cardiorenal syndrome
- Myocardial infarction (heart attack)
Chronic Kidney Diseases as a Risk Factor for Cardiorenal Syndrome
- Anti-inflammatory agents,
- ACE inhibitors
Symptoms of Cardiorenal Syndrome
Non-Specific Symptoms of Cardiorenal Syndrome
- Nausea and vomiting
Specific Symptoms of Cardiorenal Syndrome
Symptoms Caused by Associated Diseases-
Diagnosis of Cardiorenal Syndrome
Tests to Diagnose Cardiorenal Syndrome
The tests for diagnosing cardiorenal syndrome depend on where the problem has begun. If the problem is started in the heart then tests include blood tests, chest X-ray, heart CT Scan, cardiac catheterization, electrocardiogram (ECG), stress electrocardiogram, Holter monitoring.
If the illness has started in the kidney then urine test, blood test, kidney tissue tests are conducted. Since cardiorenal syndrome affects both kidney and heart it is likely that the doctor will ask for tests which are related to both the functioning of heart and kidneys.
Lab Test for Kidney Failure
- Urine Examination
- Blood in urine
- Creatinine clearance test
- Increase urine glucose excretion as in diabetes
- Blood Examination
- Increases Blood urea nitrogen and creatinine
- Low hemoglobin
- Increase blood glucose
- Radiological Studies
- CT scan of kidney
- Magnetic Resonance Imaging of kidney
- Electrocardiogram: Following diseases are diagnosed
- Echocardiogram: Following diseases are diagnosed
- Congestive heart failure
- Check coronary (heart) and renal (kidney) blood supply
Treatment for Cardiorenal Syndrome5
Since each individual with cardiorenal syndrome has a different risk profile, medical history and combination of comorbidities there is no straight forward treatment approach even today.
Since the patients’ body has the capability to resist numerous standard therapies such as inotropes and diuretics and this has led to an increased concern about novel treatments.
It is very important for the doctors to make sure that the victims’ blood pressure is normal. Similarly the weight of the sufferer should also be taken into account. If the sufferers’ blood pressure is low then it is recommended that the patient takes only 1 liter of water per day. The blood pressure also has to be monitored continuously.
Diuretics which are also called as water pills are the first line of treatment for cardiorenal syndrome. In clinical practices, low doses of dopamine are commonly used together with diuretic therapy. There is however available data that does not clearly support favorable effects on the kidney function.
If the renal dysfunction in cardiorenal syndrome is due to low CO, a trial of inotropic therapy using milrinone or dopamine may also be considered. There is a negative impact on survival of acute and chronic heart failure that use inotropes basing on systematic reviews.
Ultra filtration treatment modality is also useful as a palliative measure in cases of chronic cardiorenal syndrome when the renal functional is declining despite using loop diuretics and also when the patient is extremely edematous. Ultra filtration however does not provide a long term solution to the chronic cases of cardiorenal syndrome. The patients often continue to retain fluid. The condition may further worsen the already compromised renal function if the dose of diuretics is increased.
In case of renal insufficiency then ACE inhibitors should be used cautiously. ACE inhibitors should be started at a lower dose while monitoring the patient’s hydration status in order to reduce the incidence of renal dysfunction. The accompanying intake of the NSAIDs should be avoided.
Cardiac transplantation treatment modalities have a very low clinical applicability because of the high surgical risks involved and poor prognosis. Candidates for cardiac transplantation are the patients with substantial reduction in exercise capacity.
- Fluid control
- Correct protein loss
- Dialysis- For End Stage Renal Disease
- Cardiac Arrhythmia- List of Anti-Arrhythmic Medications are as Follows:
- Amiodarone (Cordarone, Pacerone)
- Bepridil Hydrochloride
- Congestive Heart Failure
- ACE Inhibitors: Useful for protection of cardiac and renal tissues
- Beta Blocker- Indicated to treat arrhythmia, cardiomegaly and cardiomyopathy
- Calcium Channel Blocker- Indicated for hypertension, arrhythmia and cardiomyopathy.
Prevention of Cardiorenal Syndrome
Living an active life, exercising, eating healthy foods, avoiding stress is very crucial in preventing cardiorenal syndrome.
Prognosis/Outlook for Cardiorenal Syndrome
Patients of cardiorenal syndrome have got poor outcome or prognosis considering the unclear pathophysiology and the treatment modality of the condition. A worsened prognosis is associated with a rise in serum creatinine or decrease in creatinine clearance in patients. If the decrease in creatinine clearance is accompanied by oliguria then the prognosis is even poorer. Two of the three non-invasive measures found to predict in hospital mortality drawn from ADHFNR (Acute Decompensated Heart Failure National Registry) analysis were reflections of kidney function; systolic blood pressure, baseline blood urea nitrogen levels and serum creatinine concentrations. The probably of the patient surviving can be reduced by 50 percent if the patient receiving dialysis has got heart failure.
Risk Factors for Cardiorenal Syndrome
The risk factors include the following; old age, comorbin conditions such as anemia, diabetes mellitus and uncontrolled hypertension. Medications such as diuretics, NSAIDs, aldosterone receptor antagonists and ACE inhibitors are also risk factors of cardiorenal syndrome. History of heart failure or impaired ventricular ejection fraction, prior myocardial infarction, elevated cardiac troponin, and chronic kidney disease are also risk factors of cardiorenal syndrome.
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