The National Institute for Health and Clinical Excellence (NICE) has issued full guidance to the NHS in England, Wales, Scotland and Northern Ireland on Percutaneous closure of patent foramen ovale for the secondary prevention of recurrent paradoxical embolism in divers.

NICE has also written guidance on this procedure for:


The foramen ovale is a hole in the wall that divides the two upper chambers of the heart. The hole is present in the heart of a developing fetus, but normally closes up soon after the baby is born. If it fails to close it is known as a patent foramen ovale (PFO) and in most people causes no problems. However, some studies have shown that having a PFO can increase the chance of substances (e.g. gas bubbles or blood clots) crossing from the right side into the left side of the heart, and from there into the arterial circulation where they may block blood vessels and cause serious problems such as a stroke. In divers resurfacing too quickly from a dive, bubbles of gas can form in the veins and cross into the arterial circulation causing permanent damage with stroke-like symptoms.

This procedure involves passing a device through a large vessel in the groin up into the heart and closing/blocking the hole in the wall. The aim is to lower the chances of substances crossing the heart and causing serious problems.

Coding and clinical classification codes for this guidance

Your responsibility

This guidance represents the view of NICE, arrived at after careful consideration of the evidence available. When exercising their judgement, healthcare professionals are expected to take this guidance fully into account, and specifically any special arrangements relating to the introduction of new interventional procedures. The guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer. 

All problems (adverse events) related to a medicine or medical device used for treatment or in a procedure should be reported to the Medicines and Healthcare products Regulatory Agency using the Yellow Card Scheme.

Commissioners and/or providers have a responsibility to implement the guidance, in their local context, in light of their duties to have due regard to the need to eliminate unlawful discrimination, advance equality of opportunity, and foster good relations. Nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties. Providers should ensure that governance structures are in place to review, authorise and monitor the introduction of new devices and procedures.

Commissioners and providers have a responsibility to promote an environmentally sustainable health and care system and should assess and reduce the environmental impact of implementing NICE recommendations wherever possible.

  • National Institute for Health and Care Excellence (NICE)