Percutaneous closure of a patent foramen ovale causing exercise hypoxemia: Case report and a review of the literature

Provoked exercise desaturation is a rare presentation of patent foramen ovale (PFO), when vigorous exercise leads to desaturation of arterial blood and subsequent dyspnea. We present a case of provoked exercise desaturation and curative percutaneous closure and review the literature. A 54-year-old male patient presented with shortness of breath during exercise in the pneumology outpatient department. During exercise spirometry, a relevant drop in arterial oxygen saturation and partial pressure of oxygen was observed and a right-left shunt suspected. In a transesophageal echocardiogram, a PFO was observed. Cardiac catheterization documented a right-left-shunt causing desaturation during exercise. Following percutaneous closure of the PFO, exercise induced desaturation was no longer detectable during exercise spirometry and there was considerable improvement in exercise capacity and subjective dyspnea. To sum up, provoked exercise desaturation is a rare but curable presentation of PFO. Percutaneous closure is a safe and effective way to treat this entity.

Importance of an adequately performed Valsalva maneuver for detecting a right-to-left shunt indicating foramen ovale reopening

OBJECTIVES

The purpose of this study was to investigate the importance of an adequately performed Valsalva maneuver for detecting a right-to-left shunt indicating reopening of the functional closure of the foramen ovale.

METHODS

We prospectively analyzed 260 patients (102 women and 158 men; mean age ± SD, 41 ± 19 years; range, 13-83 years) who underwent transesophageal echocardiography and agitated saline injection. Two-dimensional echocardiography, color Doppler imaging, and microbubbles were used to detect right-to-left shunts, and the Valsalva maneuver was performed to determine whether the functional closure of the foramen ovale had reopened.

RESULTS

Transesophageal echocardiography with color Doppler imaging identified a patent foramen ovale in 20 patients: 18 patients with a patent foramen ovale had left-to-right shunts, and 2 patients with atrial septal defects had bidirectional shunts. Both patients with atrial septal defects showed right-to-left shunt microbubbles without and with the Valsalva maneuver, whereas all 18 patients with a patent foramen ovale showed right-to-left shunt microbubbles only after the Valsalva maneuver. Foramen ovale reopening was identified by transesophageal echocardiography in an additional 40 patients with no shunt during rest on agitated saline injection and in whom the right-to-left shunt appeared only after the Valsalva maneuver. The Valsalva maneuver could cause an atrial septal swing, and its sensitivity and specificity were 100%.

CONCLUSIONS

An adequately performed Valsalva maneuver is important for detecting a right-to-left shunt indicating reopening of the functional closure of the foramen ovale.

Provoked exercise desaturation in patent foramen ovale and impact of percutaneous closure

OBJECTIVES

This study was designed to assess the prevalence of provoked exercise desaturation (PED) in patients with patent foramen ovale (PFO) referred for cardiovascular evaluation and to evaluate the impact of PFO closure.

BACKGROUND

Platypnea orthodeoxia syndrome is a rare, mechanistically obscure consequence of PFO that results in oxygen desaturation during postural changes. In our clinical experience, however, it is far less common than desaturation during exercise.

METHODS

This was a single-center prospective study of 50 patients with newly diagnosed PFO. Each patient underwent standardized assessment for arterial oxygen saturation with pulse oximetry during postural changes and stair climbing exercise. Provoked exercise desaturation was defined as a desaturation of at least 8% from baseline to <90%. All patients who underwent closure were reevaluated 3 months after the procedure. Those with baseline PED were similarly reassessed for desaturation at follow-up.

RESULTS

Mean age of the cohort was 46 ± 17 years, 74% were female, 30% had migraines, and 48% had experienced a cerebrovascular event. Seventeen patients (34%) demonstrated PED. Provoked exercise desaturation patients seemed demographically similar to non-PED patients. Ten PED patients underwent PFO closure (2 surgical, and 8 percutaneous). Drop in oxygen saturation was improved by an average of 10.1 ± 4.2% after closure (p < 0.001), and New York Heart Association functional class improved by a median of 1.5 classes (interquartile range: 0.75 to 2.00, p = 0.008).

CONCLUSIONS

One-third of patients referred for assessment of PFO experience oxygen desaturation during stair exercise. Closure of PFO seems to ameliorate this phenomenon and improve functional status.

Paradoxical emboli--clinical importance of transcranial Doppler for detection of patent foramen ovale

A patent foramen ovale has been reported to be more frequently detected in cryptogenic stroke, with paradoxical embolism as the major pathogenetic mechanism. The standard procedure for the detection of a patent foramen ovale is transesophageal echocardiography. Transcranial Doppler sonography with bubble test is almost as reliable as transesophageal echocardiography. Seventeen patients with acute ischemic stroke and transient ischemic attacks hospitalized at the Department of Neurology in Novi Sad underwent examinations to detect a patent foramen ovale, which was found in 55.6% of patients with cryptogenic stroke. The average age of these patients was 30.6 years. Transcranial Doppler sonography showed 100% sensitivity and 100% specificity for the prediction of right-to-left shunts proven by transesophageal contrast echocardiography. Both positive and negative predictive values in our group of patients were 1. Transcranial Doppler with bubble test is a reliable method for the detection of a patent foramen ovale, with a high level of sensitivity and specificity which is comparable with transesophageal echocardiography. Moreover, it is cheaper and more comfortable than transesophageal echocardiography, and should be used routinely in neurological practice.

Prenatal cardiovascular shunts in amniotic vertebrates

During amniotic vertebrate development, the embryo and fetus employ a number of cardiovascular shunts. These shunts provide a right-to-left shunt of blood and are essential components of embryonic life ensuring proper blood circulation to developing organs and fetal gas exchanger, as well as bypassing the pulmonary circuit and the unventilated, fluid filled lungs. In this review we examine and compare the embryonic shunts available for fetal mammals and embryonic reptiles, including lizards, crocodilians, and birds. These groups have either a single ductus arteriosus (mammals) or paired ductus arteriosi that provide a right-to-left shunt of right ventricular output away from the unventilated lungs. The mammalian foramen ovale and the avian atrial foramina function as a right-to-left shunt of blood between the atria. The presence of atrial shunts in non-avian reptiles is unknown. Mammals have a venous shunt, the ductus venosus that diverts umbilical venous return away from the liver and towards the inferior vena cava and foramen ovale. Reptiles do not have a ductus venosus during the latter two thirds of development. While the fetal shunts are well characterized in numerous mammalian species, much less is known about the developmental physiology of the reptilian embryonic shunts. In the last years, the reactivity and the process of closure of the ductus arteriosus have been characterized in the chicken and the emu. In contrast, much less is known about embryonic shunts in the non-avian reptiles. It is possible that the single ventricle found in lizards, snakes, and turtles and the origin of the left aorta in the crocodilians play a significant role in the right-to-left embryonic shunt in these species.

Enhanced detection of patent foramen ovale by systematic transthoracic saline contrast echocardiography

OBJECTIVE

We aimed to evaluate the effectiveness of transthoracic saline contrast echocardiography (TSCE) in detecting patent foramen ovale (PFO).

BACKGROUND

Transesophageal echocardiography (TEE) is semi-invasive and not ideal for PFO screening.

METHODS

112 patients (48 males, 46 ± 14 years) with suspected PFO received intravenous agitated-saline contrast at rest and stress (strain and release phases of Valsalva maneuver and coughing). The presence of interatrial shunting was defined as >5 bubbles appearing in the left heart within 3 cardiac cycles. The stage of the maneuver at which interatrial shunting occurred was recorded. The TSCE findings were validated by TEE.

RESULTS

TEE identified PFO in 45% of patients. The sensitivities of TSCE in detecting PFO at rest, during strain and release of Valsalva maneuver, and coughing were 12.0%, 38.0%, 80.0% and 94.0% respectively (each p<0.05 when compared to previous stage). Specificities were similar and >95% for all stages. Moreover, the release phase of the maneuver improved the diagnostic accuracy [defined as (number of true positives+true negatives) divided by total in sample] with incremental value over the preceding strain phase (89.2 vs. 70.5%, p<0.001).

CONCLUSIONS

Patent foramen ovale can be identified confidently with proper conduct of the Valsalva maneuver during the transthoracic saline contrast echocardiography.