Review: Detection of patient foramen ovale using transcranial Doppler or standard echocardiography

Abstract

A patent foramen ovale (PFO) is a common remnant of fetal circulation present in up to 25% of the worldwide adult population. Paradoxical embolism occurs when venous blood crosses the PFO into the arterial system, bypassing the pulmonary circulation. This allows for the direct passage of microemboli into cerebral blood vessels, increasing the risk of cryptogenic stroke. This review investigates the current diagnostic procedures used to detect and grade a PFO, including transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE) and transcranial Doppler (TCD). Only a few studies have directly compared the use of TTE with TCD for PFO detection but several have compared TTE and TCD independently against the clinical gold standard TOE. Known pitfalls of TTE and TCD are also discussed, including the difficulty of differentiating between intracardiac shunts and intrapulmonary shunts. This review also discusses methods to optimise imaging, such as performing an adequate Valsalva manoeuvre, the role of abdominal compression and the choice of the injection site for the contrast agent and how these may increase the diagnostic success of detecting a right-to-left shunt when prompted by a clinician.

Comparative analysis of echocardiographic and clinical characteristics among patients afflicted by embolic stroke of undetermined source and migraine, both accompanied by patent foramen ovale

“…PFO length was greater in ESUS patients compared to migraine patients (Migraine: 10 mm [IQR: [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]; ESUS: 15 mm [IQR: 7-24], p=0.001), while PFO width was similar between the groups (Figure 1).…”

Comparison of echocardiographic and clinical characteristics in embolic stroke and migraine patients with patent foramen ovale

“…Risk criteria for stroke in patients with PFO can be categorized as clinical, anatomical, and functional criteria. The Risk of Paradoxical Embolism (RoPe) score is based on 12 data and is used to distinguish incidental PFO from clinically significant PFO in ESUS patients 15 (Table 2).…”

“…PFO length was greater in ESUS patients compared to migraine patients (Migraine: 10 mm [IQR: [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]; ESUS: 15 mm [IQR: 7-24], p = .001), while PFO width was similar between the groups (Figure 2).…”

Sonografisches Neuromonitoring auf der Stroke Unit und in der neurologischen Intensivmedizin

“…B. mittels agitierter Kochsalzlösung (oder anderen Rechtsherz-Kontrastmitteln) und TCD oder transkranieller Duplexsonografie (transcranial color-coded sonography TCCS) der Übertritt von Gasmikrobläschen vom rechten in den linken Kreislauf durch deren Nachweis im Dopplerspektrum in der A. cerebri media mit hoher Sensitivität bewiesen oder ausgeschlossen werden. Die neurosonografische Technik hat gegenüber der transösophagealen Echokardiografie den Vorteil eines bei wachen Patienten besser durchzuführenden Valsalva-Manövers [37]. Während die aktuelle deutsche S2e-Leitlinie sehr großzügig über die ESUS-Kriterien die Indikation zum PFO-Verschluss stellt wird anderseits sehr kritisch über das häufig zufällige Vorhandenseins eines PFO spekuliert [38,39].…”