Medical

The heart-kidney link

Heart and kidney illustration

Ever wondered why heart and kidney diseases often go together? Dr Paul Kalra, consultant cardiologist at Queen Alexandra Hospital, Portsmouth, talks to Judy O’Sullivan about how our vital organs interact.

Imagine there’s been an accident on one of the motorways linking some of the UK’s major cities. It’s rarely just the one road that’s affected – a traffic jam on one major route often leads to congestion on others.

The same is true for your body. Think of your vital organs as key cities linked together by a network of motorways and main roads – the arteries and veins. When there’s a problem in one, things often go wrong elsewhere. This is especially true of the heart and kidneys, which work very closely together.

How they work together

The heart’s job is to send a continuous supply of oxygenated blood around the body. The kidney filters the blood, extracting waste in the form of urine, and also helps regulate the water and salt levels to control blood pressure.

Relatively recent research has shown that heart failure is a significant risk factor for kidney disease

Relatively recent research has shown that heart failure is a significant risk factor for kidney disease. When the heart is no longer pumping efficiently it becomes congested with blood, causing pressure to build up in the main vein connected to the kidneys and leading to congestion of blood in the kidneys, too. The kidneys also suffer from the reduced supply of oxygenated blood. 

When the kidneys become impaired, the hormone system, which regulates blood pressure, goes into overdrive in an attempt to increase blood supply to the kidneys. The heart then has to pump against higher pressure in the arteries, and eventually suffers from the increase in workload. 

It’s routine for doctors to check your kidney function if they believe you may have heart disease. A simple blood test can check if the level of creatinine, a waste product usually secreted by the kidneys, is raised, suggesting impairment. Some patients may also need an ultrasound or CT scan to help examine their kidneys’ structure and function.

Can it be treated?

Combined heart and kidney disease is usually treated with several drugs. Control of high blood pressure is key.

Water tablets, or diuretics, help reduce blood pressure and remove excess fluid as they make the kidneys excrete more water and salt. Swollen ankles are a common indication of excess fluid: talk to your doctor if this keeps happening to you.

Other drugs include ace inhibitors (ramipril, enalapril, lisinopril, perindopril), beta blockers (bisoprolol, carvedilol, nebivolol) and aldosterone blockers (spironolactone, eplerenone). These all benefit patients with heart failure as they counteract the over-activation of the hormone system. However, they can have a negative effect on the kidneys so it takes careful monitoring and frequent blood tests to get the balance right.

How you can reduce your risk:

  • Be a non-smoker.
  • Eat a low-salt diet.
  • Ask your doctor or nurse how to adjust drug dosage according to your blood test results and weight. Weigh yourself regularly at home to warn of fluid overload or dehydration.
  • Get to know your drugs – ask your doctor, specialist nurse or pharmacist to explain.
  • Exercise regularly – swimming, cycling, dancing or power walking all help to lower blood pressure and improve heart and muscle function.

Meet the expert

Dr Paul KalraDr Paul Kalra is a Consultant Cardiologist at Portsmouth Hospitals NHS Trust, and has a sub specialty interest in heart failure. He maintains an active research interest and has in excess of 70 peer reviewed publications. He is UK Principle Investigator for a worldwide epidemiological study for patients with coronary artery disease (CLARIFY), which has recruited almost 35,000 subjects (nearly 2,500 in UK).

He has a clinical and academic interest in patients with cardio-renal disease. He was co-organiser of the UKs first national Cardio-Renal Conference in 2006; this has now developed into a very successful annual meeting with around 150 delegates. He edited ‘Specialist Training in Cardiology’ which was Highly Commended in the 2006 BMA Medical Book Competition.

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