Foramen ovale (heart)

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Fossa ovalis (bottom left)

The foramen ovale ( Latin for “oval hole”) in the heart is a door-like connection between the atria that allows blood to pass from right ( pulmonary circulation ) to left ( body circulation ) in the fetal ( prenatal ) circulation . After birth it is one of the atrial septal defects . Since the lungs are not yet ventilated before birth and therefore not yet functionally supplied with blood, the blood flows via the foramen ovale into the left atrium and through the ductus arteriosus (or Ductus arteriosus Botalli ) from the pulmonary artery into the aorta .

Physiological closure of the foramen ovale

After birth, the newborn will inflate its lungs and begin to breathe. The vascular resistance of the lungs decreases. This also reduces the pressure in the right atrium. The blood flow is reversed and the blood now flows from the left atrium through the foramen ovale into the right atrium. The septum primum in the left atrium is pressed against the septum secundum in the left atrium: the foramen ovale closes. Later the septum primum and septum secundum grow together and create a permanent seal.

The foramen ovale, which was already known in the 16th century, usually closes in the first days or weeks of life. Instead of the hole there is a shallow pit in the heart, the fossa ovalis ("egg-round pit"). The oval fossa in the right atrium is surrounded by a border ( Limbus fossae ovalis ) and in the left it is covered by the valvula foraminis ovalis ( Falx septi ).

Persistent foramen ovale (PFO)

If the closure is not complete, one speaks of a persistent (i.e. persistent, permanent) foramen ovale (PFO; English : patent [Latin: patens ' open '] foramen ovale , abbreviation also PFO; French foramen ovale perméable , abbreviation FOP). Up to 25% of all people live postnatally with an open foramen ovale in the atrial septum. The best information on the frequency and size of the PFO is provided by the systematic examination of the heart of the deceased by the pathologist ( autopsy ). At the Mayo Clinic in the United States, 965 hearts of the deceased were examined for the presence of a PFO. A PFO was found in 27.3%. The frequency was the same for both sexes, but the frequency and size decreased with age: 34.3% in the first three decades , 25.4% in the 4th to 8th decades and 20.2% in the 9th and 8th decades 10th decade. The size varied from 1 to 19 mm and averaged 4.9 mm. The mean size of the PFO increased with age: 3.4 mm in the first decade and 5.8 mm in the 10th decade of life. Many open oval foramina are undiscovered until death. Therefore the frequency in clinical studies is often lower. With the help of color Doppler echocardiography , a small amount of blood flow through this opening can then be detected. The children are not affected and treatment is usually not necessary even in adulthood. However, if the opening is large and hemodynamically significant, it is more likely to be assigned to atrial septal defect II (ASD II).

Stroke with PFO

The majority of ischemic strokes are caused by emboli. A paradoxical embolism is when the blood clot originates from the veins of the great circulation and bypasses the pulmonary vessels through the PFO into the arteries of the great circulation. If an end artery of the brain is closed, an ischemic apoplexy develops. The examination after a stroke usually reveals other causes, for example a severe narrowing of a carotid artery , atrial fibrillation or a previous dissection of the afferent cerebral arteries. In about 1/6 of the patients, the cause of the embolism remains unclear. This type is called “embolic stroke of undetermined source”, that is, embolic stroke with an unknown cause. Since every fourth patient statistically has a PFO, a paradoxical embolism need not be the cause of the stroke. The RoPE (Risk of Paradoxical Embolism) score was developed to decide whether it makes sense to occlude the PFO. The RoPE score takes into account high blood pressure , diabetes , smoking , previous strokes or TIAs , the cortical location of the current cerebral infarction and the patient's age. The RoPE score is a number between 0 and 10, with the larger numbers indicating a higher probability that it is a paradoxical embolism from the PFO.

Risk of stroke after non-cardiac surgery with PFO

With PFO, the risk of ischemic stroke is increased after non-cardiac surgery under general anesthesia . In a retrospective cohort study , 150,198 patients with non- cardiological surgery under general anesthesia were analyzed. A PFO was known in 1540 patients (1%); no PFO was documented in 148,658. Up to the 30th day after surgery, 850 (0.6%) ischemic strokes were observed. With PFO there were 49 (3.2%) strokes, without PFO 801 (0.5%). However, the patients with PFO were older and had more risk factors (e.g. hypertension , diabetes , atrial fibrillation ). A regression analysis that took into account all known risk factors nevertheless showed an increased risk of stroke for patients with PFO.

Diving with PFO

Open foramina ovalia are particularly important in scuba diving , where microbubbles can enter the arterial system during the dive when the pressure is equalized ( Valsalva experiment ). In a case series of diving accidents at the University Hospital Düsseldorf , more than half of the diving accidents treated there could be traced back to the PFO.

According to recent research, there is a connection between a PFO and migraines . Migraine attacks disappeared or decreased in some adults whose PFO was blocked.

The latest findings indicate that pocket-shaped remnants of the foramen ovale in the left atrium are associated with strokes of unknown origin (especially in younger people), since blood clots can form in such a pocket.

Premature closure of the foramen ovale in the fetus

If the foramen ovale in the fetus narrows or closes before birth , this is a life-threatening risk factor for the circulatory change in the child after birth. Therefore, severe constrictions or occlusions of the foramen ovale are treated before birth in the womb in order to improve postnatal treatment options. This is possible with a minimally invasive procedure .

Web links

Individual evidence

  1. ↑ Gerhard Bauriedel, Dirk Skowasch, Alexander Jabs, René Andrié, Alexander Hartmann, Berndt Lüderitz : Treatment options for symptomatic open foramen ovale . In: Deutsches Ärzteblatt , 2003, Volume 100, Issue 34–35 / 2003, pp. A 2230 - A 2235.
  2. ↑ Barbara I. Tshisuaka: Pineau (Pinaeus), Severin. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 1163.
  3. ↑ PT Hagen, DG Scholz, WD Edwards: Incidence and size of patent foramen ovale during the first 10 decades of life: an autopsy study of 965 normal hearts . In: Mayo Clinical Procedures , 1984, Volume 59, Issue 1, pp. 17-20.
  4. ↑ MY Mi, PC Block, JP Broderick: Clinical Decisions: PFO Closure for Cryptogenic Stroke . tape 378 , issue 17, 2018, p. 1639–1642 (English, nejm.org [accessed December 11, 2018]).
  5. ↑ Emiliya Melkumova, David E. Thaler: Cryptogenic Stroke and Patent Foramen Ovale Risk Assessment . In: Interventional Cardiology Clinics . tape 6 , no. 4 , October 1, 2017, ISSN  2211-7466 , p. 487-493 , doi : 10.1016 / j.iccl.2017.05.005 ( theclinics.com [accessed December 11, 2018]).
  6. ↑ PY Ng, AKY Ng, B. Subramaniam and others: Association of preoperative diagnosed patent foramen ovale with perioperative ischemic stroke. JAMA ( Journal of the American Medical Association ) 2018; Volume 319: pages 452-462.
  7. ↑ Thomas Kromp , Hans J. Roggenbach, Peter Bredebusch: Practice of diving. Delius Klasing Verlag (Edition Nagelschmid), Stuttgart 2007, ISBN 978-3-7688-1816-2 .
  8. ↑ Diving accidents are increasing: examine first, then dive. Press release from the University Hospital Düsseldorf, August 10, 2007.
  9. ^ Sue Hughes: The atrial septal pouch - a new source of thrombus? medscape.com, January 29, 2010.
  10. ↑ PY Ng, AKY Ng, B. Subramaniam et al .: Association of preoperative diagnosed patent foramen ovale with perioperative ischemic stroke. In: JAMA , 2018, 319, pp. 452–462.
  11. ↑ UMM: Closure of the foramen ovale: University Hospital Mannheim. Retrieved July 26, 2018 .

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