Dye dilution and oximetry for detection of patent foramen ovale

Abstract

Objectives ‐ Patent foramen ovale (PFO) is a risk factor for stroke of undetermined (cryptogenic) origin. Low cost and non‐invasive bedside tests for detection of PFO are needed as alternatives to contrast transesophageal echocardiography. We investigated whether dye dilution curves and oximeter recordings are useful for detecting PFO and what is the prevalence of PFO in patients with cryptogenic stroke determined with these bedside methods. We also studied whether stroke risk factors, number of brain lesions, and stroke recurrence rates were different in patients with an unexplained stroke with and without PFO. Material and methods ‐ Dye dilution curves and oximeter recordings with non‐invasive earpiece apparatus were obtained in 59 patients aged under 50 years who had had a cryptogenic brain infarction. The number of ischemic lesions in the brain was counted by MRI. Results ‐ PFO was found in 24 (41%) of 59 patients. There was a 100% concordance in results obtained by dye dilution and by oximetry. Risk factors for stroke were similar in subjects with PFO and those without PFO. No significant association was found between PFO and Valsalva‐like activity at stroke onset. Those with PFO did not have more ischemic lesions detected by MRI nor did they have more recurrent ischemic episodes. Conclusion ‐ Dye dilution and oximetry are cheap and useful methods for detection of PFO and could be used for screening of the risk of paradoxical embolism. Because these 2 methods were not compared with the golden standard, transesophageal echocardiography, the specificity and sensitivity of the tests remain unsettled.

Non-invasive dye dilution method for measuring an atrial septal defect shunt size

“…One of the authors of this paper (MV) designed the densitometer and the software for the computer analysis of the dye dilution curves and the oximeter recordings. 18 20 The equipment became available for clinical use in 1993.…”

“…can also be detected non-invasively using an earpiece densitometer. [18][19][20][21] The purpose of this study was to evaluate the efficacy of shunt size calculation using this non-invasive dye dilution method with indocyanine green solution and compare it to the gold standard of invasive oximetric quantitation of shunting using Fick's principle. Second, we evaluated how well the measured shunt size correlates to the native and invasive stop-flow balloon measured size of the ASD on TEE.…”

Patent foramen ovale

“…First suggested by Karltunen et al, 25 pulse oximetry (SpO 2 ) via an ear sensor has been utilized for RLS screening through the detection of an oxygen desaturation response following repetitive Valsalva procedures.…”