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referral guide PFO/ASD  practitioner main page Whats a PFO?
A patent foramen ovale (PFO) is a small flap like structure that permits flow from the right to the left side of the heart whilst the fetus is in utero. As a fetus is using the placenta and mother for oxygenation and nutrition, the majority of blood flow is redirected away from the lungs through this flap. When a baby is born and commences normal breathing  the pressures and blood gas levels change and cause the flap to close. It is now understood that in 10% and perhaps up to 30% of the population that flap does not close completely. Of that percentage, a small number of people develop problems from the crossing over (shunting) of blood from the right atrium directly to the left atrium. Problems arise because the blood in the right side of the heart has been returned from all parts of the body. It is low in oxygen, high in carbon dioxide, it may have partially degraded blood cells (red blood cell, platelets, white blood cells), other by-products, proteins present that are potentially harmful if recirculated in the body. The lung is an incredible filter of not only gases such as oxygen and carbon dioxide but it plays a role in the purification of our blood. Therefore, if a volume of blood is shunted away before it can be processed and returned to the arterial (left heart) side of the body it can have damaging effects. One of the most serious effects would be for some clotted venous blood to pass through the shunt and be pumped into the brain and cause a stroke, or into the arteries that supply the heart causing a heart attack. The opening of this flap is often intermittent and may be exacerbated by increased pressure on the right side of the heart, increased stress, coughing, straining, extreme exercise and scuba diving (pressure changes). Whats a PFO  2  3 

Practitioners

Sharpe Cardiology and Endovascular provide unique cardiovascular services to South East Queensland and Northern New South Wales. We provide a holistic head to toe cardiovascular service. We aim to efficiently assess and treat all existing and new patients. How do we do this?... multidisciplinary approach (experienced cardiac nurse, cardiac and vascular technicians) pre-consult assessment and testing (most of the essential screening and baseline testing is done on the same day prior to the initial consult with Dr Sharpe). Good referral details are essential. same day assessment with initiation of a clear treatment plan patients requiring urgent intervention or treatment can be admitted the same/ next day for angiography/ stenting etc. Please refer to our services page to find out what consulting and testing services available. click here.         

TRANSCRANIAL DOPPLER INVESTIGATION

FOR PATENT FORAMEN OVALE/ ATRIAL SEPTAL DEFECT

we have a dedicated website for patients explaining PFO and relationships between migraine and stroke click here to view
One of the problems facing general practitioners when it comes to patent foramen ovale (PFO) screening has been who should be screened and then finding that there was not  a reliable simple screening test available - that is until now.  That test is called Transcranial Doppler Imaging (TCDI) with contrast.   The current tests have not been suitable as screening tools for a number of reasons including poor sensitivity, invasiveness and expense.  TCDI has been validated as a method for PFO screening having high shunt detection sensitivities, when compared to Transoesophageal echocardiography. It should be noted that if a TCDI is positive then a TOE is required to document whether the shunt is cardiac, and if so what is the type of PFO or Atrial septal defect present (this is important in device selection as some devices are inappropriate based on anatomical considerations and it also helps guide correct technique when placing the closure device). TCDI will also detect pulmonary arterio-venous fistula and malformations. Patients suffering from Haemorrhagic Heriditary Telangectasia (HHT) for instance may have AVM’s detectable by TCDI.  What is TCDI and how is it done? 	The test is done in the office with the patient awake and sitting in a comfortable chair. A venous arm canula is placed for contrast injection (often just saline, although I use a special contrast agent to achieve high sensitivity).  Multiple low intensity Doppler signals of 2.5MHz are focused on the cerebral vessels usually from a temporal window. If a shunt is present the contrast will cross to the arterial circulation often needing the help of a valsalva maneuver to open the PFO flap. When the contrast passes through the cerebral vessels we see a ‘hit” (High Intensity Transient Signal) which is an altered signal seen on the screen. The entire test takes about ten minutes in trained hands and is cost effective.   Why has it not been available until now?	 Few cardiologists have been trained in this area as it was not initially a test of a cardiac disease state when first used; the rebate is low and the equipment expensive. TCDI compliments my interest in carotid, endovascular and stroke intervention so really it is a necessary tool of the trade.  Who should be referred for TCDI?	Clearly not everyone as most PFOs are not clinically significant. We and others have found that TCDI positivity closely correlates to the probability of PFO closure efficacy.  Once found should the PFO be closed?  Not always. This recommendation is on a case by case basis.   Click here to view our YouTube page with a video of a PFO closure by Dr Sharpe. Further information can be found under PFO/ASD closures under the services page.   Table: reference guide for PFO/ASD screening using TCDI with contrast     Table: Reference guide for PFO screening using TCDI                     Migraine with Aura    SCUBA Divers     Cryptogenic CVA/TIA i.e. patients <60 years  without a definable cause •	Life disabling symptoms and frequent events •	Failed medical therapy •	Intolerance to medical therapy •	Focal neurology •	MRI evidence of silent CVA   •	Divers with history of migraine should be screened as per section A4.8(c) of the SPUMS diving medical guidelines. •	Commercial, military and advanced recreational/ technical divers are strongly advised to undergo screening, as is the norm in Europe & USA. •	Any diver with an unexplained decompression illness (DCI) event    •	40- 60% of patients will have a significant PFO and this places the patient at 3-4 times greater risk of a secondary event. It is mandatory to exclude shunt in these patients.