Reducing painful shocks in people with implanted defibrillators

12 February 2016        

How an ICD is inserted

We are funding researchers at Imperial College London £200,000 to find new ways of reducing the number of damaging and painful shocks that people with an implantable defibrillator receive.

BHF Research Fellow Dr Zachary Whinnett and his team are working towards creating a new therapy to help the heart withstand an abnormal heart rhythm without the need to immediately deliver an often painful and potentially damaging electric shock. 

During an abnormal rhythm, the new therapy will be designed to ensure the heart continues to supply blood to the brain and the body until a normal heart rhythm resumes. 

What is an ICD?

People at risk of developing an abnormal heart rhythm known as ventricular tachycardia (VT) are often fitted with an implantable cardioverter-defibrillator (ICD), which acts as both a pacemaker and defibrillator. 

The footballer Fabrice Muamba was fitted with an ICD after he survived a cardiac arrest back in 2012. The device is fitted internally to deliver either an Anti-tachycardia pacing (ATP) therapy or shocks to the heart when VT takes place, and prevents the onset of a cardiac arrest, which could otherwise be deadly.

How would it work?

Dr Zachary Whinnett, the lead researcher on the study at Imperial, spoke about the “massive” potential impact that a new therapy could have for people with an ICD:

“Shocks delivered by ICDs are painful and can be harmful, both psychologically to the patient and physically to the heart. For a person with an ICD, ATP therapy and shocks are vital, but we want to develop a new treatment which can be delivered by an ICD to support the heart during ventricular tachycardia episodes in order to maintain heart function.

“If successful this research could have huge implications for patients with VT, by reducing the number of potentially harmful shocks and ATP therapies delivered to the heart, and providing them with a safe alternative.” 

How does a shock feel?

Rehana Browne, aged 25 from London, had her ICD fitted in 2013 after suffering a cardiac arrest while in the gym which was caused by an abnormal heart rhythm. She has since had a shock from her ICD while she was out jogging.

Rehana said: “I was trying to build up my fitness again. I had been put in a medically induced coma following my cardiac arrest and was in intensive care for four days so I had to build it up slowly. I went for a jog and a funny feeling came over me so I stopped. Seconds later the shock came. It was really, really painful, more so than I had been expecting. I felt quite shaky afterwards although I’m not sure if that was due to emotional shock or physical shock from the pain. After that I wasn’t able to drive for 6 months. Luckily I haven’t had another one since but I suppose it is always in the back of my mind.”

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