What is the bubble test and what is it for? Bubble testing or microbubble testing is a minimally invasive, ultrasound-based method that allows the detection of any communication between right and left sections within the heart cavities. The most frequent and known case is PFO (Pervio Oval Foramen). PFO is a kind of "hole" in the intertrinal sept, present in 25-30% of the population. Before birth, in the foetal period, this hole promotes the passage of blood between the two atria and is therefore important to distribute oxygen and blood to the body. At birth, however, and within the first year of the newborn's life, the whole septet should physiologically close, because in the meantime the lungs are activated. If this closure does not take place we speak of "the persistency of the oval foramen". In a very small percentage of cases this can cause cerebral ischemia and/or neurological symptoms. How does the bubble test take place? The examination consists of infusing from a superficial vein of the arm a saline solution (mixed or not with a gel suitable to increase its viscosity) capable of forming small bubbles that have no interference in the body. These bubbles under the pressure of venous circulation reach the heart and, in case of the presence of shunt between the heart chambers, it is possible to observe the direct passage from the right sections to the left sections through a transtoracic echocardiogram. The nurse will place a venous access before the start of the examination, using an agocannula from which the previously prepared solution will then be injected. After 5 seconds of infusion, the patient will be asked to perform a Valsalva manoeuvre (forced closed glottis exhalation) that increases abdominal pressure and, consequently, in the right atrium. In case of abnormal communication, bubbles will be passed through the arterial circle. The timing of the passage of these bubbles may point to the location of this abnormal passage (early at the heart level, late in the extracardial level). The entire procedure will be repeated later under ecodoppler monitoring of the average brain artery through a temporal or occipital transcranial window. This second step allows the quantification and grading of the defect according to a standardized classification. What are the limits and risks? The bubble test is an extremely safe method whose limits are exclusively related to the presence or not of a suitable acoustic window to the transthoracic echo and/or transcranial doppler. In rare cases, vague reactions (lowering blood pressure, dizziness and weakness, blurring of vision) can occur as a result of administration of solution prepared for infusion. However, the necessary medical facilities are readily available to deal with this situation and the staff is trained to handle emergency situations. How long does the bubble test last? The bubble test is typically run in 20 minutes. It is not a painful, or invasive examination. It consists of a simple ultrasound evaluation performed after administration of physiological solution. How to prepare for the test. The bubble test is a simple execution survey and does not involve major side effects, requires no preparation and allows you to return to your activities immediately after the exam. The test is indicated in all cases of Ischemic Transient Attacks (TIA) or Stroke of an undefined nature. What are the possible alternatives? The bubble test is the only examination capable of providing a diagnosis of certainty regarding the presence of intracardiac shunts along with the quantitative functional data of any pathological findings. The results of the bubble test should be supplemented with an assessment of the significance of any pathological shunts found, in case a chryptogenetic stroke/TIA diagnostic process is being carried out using cerebral MRI. An alternative examination of the bubble test for morphological evaluation of intracardiac defects is the transesophageal ecocolordoppler, which nevertheless represents a superior invasiveness examination and does not allow an equally accurate functional grading.