Atrial Fibrillation After Patent Foramen Ovale Closure: Incidence, Pathophysiology, and Management

This comprehensive review explores the incidence, pathophysiology, and management of atrial fibrillation (AF) following percutaneous closure of patent foramen ovale (PFO). Although AF is considered a common adverse event post PFO closure, its incidence, estimated at <5%, varies based on monitoring methods. The review delves into the challenging task of precisely estimating AF incidence, given subclinical AF and diverse diagnostic approaches. Notably, a temporal pattern emerges, with peak incidence around the 14th day after closure and a subsequent decline after the 45th day, mimicking general population AF trends. The pathophysiological mechanisms behind post PFO closure AF remain elusive, with proposed factors including local irritation, device-related interference, tissue stretch, and nickel hypersensitivity. Management considerations encompass rhythm control, with flecainide showing promise, and anticoagulation tailored to individual risk profiles. The authors advocate for a personalized approach, weighing factors like age, comorbidities, and device characteristics. Notably, postclosure AF is generally considered benign, often resolving spontaneously within 45 days, minimizing thromboembolic risks. Further studies are required to refine understanding and provide evidence-based guidelines.

Ignored Role of Paroxysmal Atrial Fibrillation in the Pathophysiology of Cryptogenic Stroke in Patients with Patent Foramen Ovale and Atrial Septal Aneurysm

The association between cryptogenic stroke (CS) and patent foramen ovale (PFO) with or without atrial septal aneurysm (ASA) has been a debate for decades in terms of pathophysiologic processes and clinical courses. This issue has become more interesting and complex, because of the concerns associating the CS with so-called normal variant pathologies of interatrial septum, namely ASA and PFO. While there is an anatomical pathology in the interatrial septum, namely PFO and ASA, the embolic source of stroke is not clearly defined. Moreover, in patients with PFO and CS, the risk of recurrent stroke has also been associated with other PFOunrelated factors, such as hyperlipidemia, body mass index, diabetes mellitus, and hypertension, leading to the difficulty in understanding the pathophysiologic mechanism of CS in patients with PFO and/or ASA. Theoretically, the embolic source of cryptogenic stroke in which PFO and/or ASA has been involved can be categorized into three different anatomical locations, namely PFO tissue and/or ASA tissue itself, right or left atrial chambers, and venous vascular territory distal to the right atrium, i.e., inferior vena cava and lower extremity venous system. However, the possible role of paroxysmal atrial fibrillation associated with PFO and/or ASA as a source of cryptogenic stroke has never been mentioned clearly in the literature. This review aims to explain the association of cryptogenic stroke with PFO and/or ASA in a comprehensive manner, including anatomical, clinical, and mechanistic aspects. The potential role of paroxysmal atrial fibrillation and its contribution to clinical course have been also discussed in a hypothetical manner to elucidate the pathophysiology of CS and support further treatment modalities.

Impact of Patent Foramen Ovale Anatomic Features on Right-to-Left Shunt in Patients with Cryptogenic Stroke

The purpose of this study was to investigate the impact of the morphologic characteristics of patent foramen ovale (PFO) on right-to-left shunt (RLS) in patients with PFO and cryptogenic stroke using transesophageal echocardiography and saline contrast transthoracic echocardiography (c-TTE). Of the 165 patients with PFO stroke, both the height and the length of PFO in the provoked RLS group were smaller than those in the constant RLS group. PFO height, interatrial septum mobility and proportion of atrial septal aneurysms were greater in the severe RLS group than in the mild and moderate RLS groups. Multivariate analysis revealed that PFO height and interatrial septum mobility were independent predictors of severe RLS. Multiple territorial ischemic lesions were more common in the severe RLS or constant RLS group. Our findings indicated that the severity of RLS was related to the anatomic features in PFO, inducing different cerebral ischemia lesion patterns in cryptogenic stroke patients with PFO.

Hypoxemia in COVID-19 patients: An hypothesis

The current SARS-Cov-2 virus pandemic challenges critical care physicians and other caregivers to find effective treatment for desperately ill patients - especially those with sudden and extreme hypoxemia. Unlike patients with other forms of Acute Respiratory Distress Syndrome, these patients do not exhibit increased lung stiffness or dramatic dyspnea., even in the presence of arterial blood oxygen levels lower than that seen normally in mixed venous blood. Urgent intubation and mechanical ventilation with high inflation pressures and raised inhaled oxygen concentration have proved unhelpful or worse, but why? Our Hypothesis is that sudden opening of a previously undetected probe-patent foramen ovale (PPFO) may explain this mystery. As hypoxemia without acidosis is a rather weak stimulus of dyspnea or increased ventilation, and opening of such an intracardiac shunt would not worsen lung mechanical properties, the absence of dramatic symptom changes would not be surprising. We point out the high frequency of PFO both in life and at autopsy, and the physiological evidence of large shunt fractions found in Covid-19 patients. Published evidence of hypercoagulability and abundant evidence of pulmonary emboli found at autopsy are in accord with our hypothesis, as they would contribute to raised pressure in the pulmonary arteries and right heart chambers, potentially causing a shunt to open. We review the interaction between viral corona spike protein and ACE-2 receptors present on the surface of alveolar lining cells, and contribution to hypercoagulabilty caused by the spike protein. Search for an open PFO after a large drop in arterial oxygen saturation can be performed at the bedside with a variety of well-established techniques including bedside echocardiography, nitrogen washout test, and imaging studies. Potential treatments might include balloon or patch closure of the shunt, and various drug treatments to lower pulmonary vascular resistance.

Right-to-left shunts and hormonal therapy influence cerebral vasomotor reactivity in patients with migraine with aura

Patent Foramen Ovale and impaired cerebral hemodynamics were proposed among the pathophysiological mechanisms explaining the increased risk for stroke in patients with Migraine with Aura (MA). Our study aimed at comparing the vasomotor reactivity (VMR) of the anterior and the posterior cerebral circulation in patients with Migraine with Aura, in patients with acute vascular ischemic accidents, and in controls. We hypothesized that VMR in MA patients is preserved in the anterior circulation and reduced in the posterior circulation. We prospectively assessed with Transcranial Doppler the vasomotor reactivity to breath holding of the Middle and Posterior Cerebral Arteries (MCA, PCA) in MA patients, in acute vascular patients and healthy controls. We also evaluated the possible effect of clinical characteristics of MA (attack frequency, aura length or type, disease history), vascular factors and the presence of right-to-left shunt on VMR. Diverging from our hypothesis, MA patients displayed a higher breath-holding index (BHI) than controls in the MCA (1.84±0.47%/s vs 1.53±0.47%/s, p = .001) as well as in the PCA (1.87±0.65%/s vs 1.47±0.44%/s, p < .001). In MA patients, MCA BHI was higher in those with large right-to-left shunts (2.09±0.42 vs 1.79±0.47, p = .046) and lower in those taking estrogens (1.30±0.30%/s vs 1.9±0.45%/s, p = .009). We did not observe an effect of MA characteristics on BHI. The increased BHI in MA patients with large right-to-left shunts could be explained by the vasoactive effect in the cerebral circulation of substances bypassing the deactivating pulmonary filters or by a constitutional trait of the vascular system associating persistent right-to-left shunts and hyper-reactive hemodynamics. Our results discourage the hypothesis that altered hemodynamics contribute to increasing the stroke risk in all MA patients. However, estrogens can lower VMR, curtailing the hemodynamic resources of MA patients.

Morphological variations of the interatrial septum in ovine heart

Smooth septum interatrial septum, patent foramen ovale (PFO) channel and atrial septal pouches (SPs) are commonly described variants in humans. Recent discoveries on the clinical significance of left-sided SP may encourage the creation of new strategies and devices for the management of SPs. However, these strategies may first be tested in the ovine model before implementation in humans. Unfortunately, little is known about the presence of SPs in ovine. In this study a total of 60 ovine (Ovis aries) hearts were examined. The interatrial septum morphology was assessed and the PFO channel and SPs were measured. The most commonly occurring variant were PFO channels (25.0%) with channel lengths of 5.4±2.3 mm. Smooth septums were observed in 18.3% of hearts. In the remaining cases, septums had a left septal ridge (15.0%), left SP (11.7%), left septal bridge (10.0%), right SP (10.0%), or had both a right SP and left septal ridge (10.0%). No double SPs were observed. The mean right SP depth was 3.4 ± 1.2 mm, and its mean ostium width and height were 7.9±1.8 mm and 2.8±1.0, respectively. For the left SP, the mean depth was 6.0±1.7mm, the ostium width was 7.9±2.4mm, and the ostium height was 4.1±1.6mm (range: 2.3-6.4mm). In conclusion the interatrial septum of ovine hearts exhibit morphologies that are more similar to humans than they are to swine, which should be taken into account during experimental studies. The presence of a left SP in sheep hearts make ovine models a promising alternative to the human heart for developing left-sided SP management devices and techniques.

Secondary prevention of cryptogenic stroke in patients with patent foramen ovale: a systematic review and meta-analysis

The aim of our study is to compare patent foramen ovale (PFO) closure versus medical treatment and antiplatelet versus anticoagulant therapy in patients with cryptogenic stroke (CS) and PFO. We conducted a systematic review and meta-analysis with trial sequential analysis (TSA) of randomized trials. Primary outcomes are stroke or transient ischemic attack (TIA) and all-cause mortality. Secondary outcomes are peripheral embolism, bleeding, serious adverse events, myocardial infarction and atrial dysrhythmias. We performed an intention to treat meta-analysis with a random-effects model. We include six trials (3677 patients, mean age 47.3 years, 55.8% men). PFO closure is associated with a lower recurrence of stroke or TIA at a mean follow-up of 3.88 years compared to medical therapy [risk ratio (RR) 0.55, 95% CI 0.38-0.81; I² = 40%]. The TSA confirms this result. No difference is found in mortality (RR 0.74, 95% CI 0.35-1.60; I² = 0%), while PFO closure is associated with a higher incidence of atrial dysrhythmias (RR 4.55, 95% CI 2.16-9.60; I² = 25%). The rate of the other outcomes is not different among the two groups. The comparison between anticoagulant and antiplatelet therapy shows no difference in terms of stroke recurrence, mortality and bleeding. There is conclusive evidence that PFO closure reduces the recurrence of stroke or TIA in patients younger than 60 years of age with CS. More data are warranted to assess the consequences of the increase in atrial dysrhythmias and the advantage of PFO closure over anticoagulants.

Echocardiographic features of PFOs and paradoxical embolism: a complicated puzzle

Patent foramen ovale (PFO) is a residual, oblique, slit or tunnel like communication in the atrial septum that persists into adulthood. It is usually an incidental finding with no clinical repercussions. Nevertheless, recent evidence supports the association between the presence of a PFO and a number of clinical conditions, most notably cryptogenic stroke (CS). There is enough evidence that paradoxical embolism is a mechanism which can explain this association. Patient characteristics and certain echocardiography-derived anatomical and hemodynamic features of PFO provide great assistance in estimating the probability of paradoxical embolism. In this review, we initially describe PFO embryology and anatomy. We extensively present the available data on clinical, anatomical and hemodynamic features of PFOs which have been correlated with increased likelihood of paradoxical embolism and recent evidence of therapeutic management.

Inspiratory and expiratory resistance cause right-to-left bubble passage through the foramen ovale

A patent foramen ovale (PFO) is linked to increased risk of decompression illness in divers. One theory is that venous gas emboli crossing the PFO can be minimized by avoiding lifting, straining and Valsalva maneuvers. Alternatively, we hypothesized that mild increases in external inspiratory and expiratory resistance, similar to that provided by a SCUBA regulator, recruit the PFO. Nine healthy adults with a Valsalva-proven PFO completed three randomized trials (inspiratory, expiratory, and combined external loading) with six levels of increasing external resistance (2-20 cmH2 O/L/sec). An agitated saline contrast echocardiogram was performed at each level to determine foramen ovale patency. Contrary to our hypothesis, there was no relationship between the number of subjects recruiting their PFO and the level of external resistance. In fact, at least 50% of participants recruited their PFO during 14 of 18 trials and there was no difference between the combined inspiratory, expiratory, or combined external resistance trials (P > 0.05). We further examined the relationship between PFO recruitment and intrathoracic pressure, estimated from esophageal pressure. Esophageal pressure was not different between participants with and without a recruited PFO. Intrasubject variability was the most important predictor of PFO patency, suggesting that some individuals are more likely to recruit their PFO in the face of even mild external resistance. Right-to-left bubble passage through the PFO occurs in conditions that are physiologically relevant to divers. Transthoracic echocardiography with mild external breathing resistance may be a tool to identify divers that are at risk of PFO-related decompression illness.

Potential Role of Patent Foramen Ovale in Exacerbating Hypoxemia in Chronic Pulmonary Disease

Patent foramen ovale has been associated with multiple pulmonary diseases, such as pulmonary hypertension, platypnea-orthodeoxia syndrome, and chronic obstructive pulmonary disease. A connection between patent foramen ovale and chronic pulmonary disease was first described more than 2 decades ago in case reports associating patent foramen ovale with more severe hypoxemia than that expected based on the severity of the primary pulmonary disease. It has been suggested that patients with both chronic pulmonary disease and patent foramen ovale are subject to severe hypoxemia because of the right-to-left shunt. Furthermore, investigators have reported improved systemic oxygenation after patent foramen ovale closure in some patients with chronic pulmonary disease. This review focuses on the association between chronic pulmonary disease and patent foramen ovale and on the dynamics of a right-to-left shunt, and it considers the potential benefit of patent foramen ovale closure in patients who have hypoxemia that is excessive in relation to the degree of their pulmonary disease.

4D flow MRI assessment of right atrial flow patterns in the normal heart - influence of caval vein arrangement and implications for the patent foramen ovale

AIM

To investigate atrial flow patterns in the normal adult heart, to explore whether caval vein arrangement and patency of the foramen ovale (PFO) may be associated with flow pattern.

MATERIALS AND METHODS

Time-resolved, three-dimensional velocity encoded magnetic resonance imaging (4D flow) was employed to assess atrial flow patterns in thirteen healthy subjects (6 male, 40 years, range 25-50) and thirteen subjects (6 male, 40 years, range 21-50) with cryptogenic stroke and patent foramen ovale (CS-PFO). Right atrial flow was defined as vortical, helico-vortical, helical and multiple vortices. Time-averaged and peak systolic and diastolic flows in the caval and pulmonary veins and their anatomical arrangement were compared.

RESULTS

A spectrum of right atrial flow was observed across the four defined categories. The right atrial flow patterns were strongly associated with the relative position of the caval veins. Right atrial flow patterns other than vortical were more common (p = 0.015) and the separation between the superior and inferior vena cava greater (10±5mm versus 3±3mm, p = 0.002) in the CS-PFO group. In the left atrium all subjects except one had counter-clockwise vortical flow. Vortex size varied and was associated with left lower pulmonary vein flow (systolic r = 0.61, p = 0.001, diastolic r = 0.63 p = 0.002). A diastolic vortex was less common and time-averaged left atrial velocity was greater in the CS-PFO group (17±2cm/sec versus 15±1, p = 0.048). One CS-PFO subject demonstrated vortical retrograde flow in the descending aortic arch; all other subjects had laminar descending aortic flow.

CONCLUSION

Right atrial flow patterns in the normal heart are heterogeneous and are associated with the relative position of the caval veins. Patterns, other than 'typical' vortical flow, are more prevalent in the right atrium of those with cryptogenic stroke in the context of PFO. Left atrial flow patterns are more homogenous in normal hearts and show a relationship with flow arising from the left pulmonary veins.

Patent foramen ovale diagnosis: The importance of provocative maneuvers

Patent foramen ovale (PFO) is a frequent congenital anomaly, but massive right-to-left shunt (RTLS) is normally prevented by higher pressures in left heart chambers. However, mechanical ventilation with positive end-expiratory pressure (PEEP) can significantly increase right atrial pressure, accentuating the RTLS, mainly after major cardiothoracic surgery. We report a patient admitted to the intensive care unit after cardiac surgery. Pre- and intraoperative transesophageal echocardiography only described an aneurysmal interatrial septum with no shunt. However, high-PEEP ventilation induced a paradoxical response with life-threatening hypoxemia, triggering further echocardiographic evaluation, revealing massive RTLS across a stretch PFO. Provocative maneuvers (Valsalva/PEEP) significantly increase echocardiographic sensitivity, unmasking silent PFO. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:58-61, 2017.

Recognition of Undiagnosed Neonatal Heart Disease

Heart defects are the most common congenital malformation. Approximately 8000 infants per year in the United States require diagnosis in the newborn period to avoid severe injury or death. It is incumbent on the neonatologist and pediatrician to expeditiously detect the presence of symptomatic heart disease so that infants can be stabilized before cardiovascular decompensation. Evaluating infants and further categorizing them into the particular pathophysiology are necessary to stabilize them in anticipation of more definitive care by the pediatric cardiac team.

Patent foramen ovale: Unanswered questions

The foramen ovale is a remnant of the fetal circulation that remains patent in 20-25% of the adult population. Although long overlooked as a potential pathway that could produce pathologic conditions, the presence of a patent foramen ovale (PFO) has been associated with a higher than expected frequency in a variety of clinical syndromes including cryptogenic stroke, migraines, sleep apnea, platypnea-orthodeoxia, deep sea diving associated decompression illness, and high altitude pulmonary edema. A unifying hypothesis is that a chemical or particulate matter from the venous circulation crosses the PFO conduit between the right and left atria to produce a variety of clinical syndromes. Although observational studies suggest a therapeutic benefit of PFO closure compared to medical therapy alone in patients with cryptogenic stroke, 3 randomized controlled trials (RCTs) did not confirm the superiority of PFO closure for the secondary prevention of stroke. However, meta-analyses of these RCTs demonstrate a significant benefit of PFO closure over medical therapy alone. Similarly, observational studies provide support for PFO closure for symptomatic relief of migraines. But one controversial randomized study failed to replicate the results of the observational studies while another two demonstrated a partial benefit. The goal of this review is to discuss the clinical conditions associated with PFO and provide internists and primary care physicians with current data on PFO trials, and clinical insight to help guide their patients who are found to have a PFO on echocardiographic testing.

Sleep Apnea in Patients with and without a Right-to-Left Shunt

OBJECTIVES

To assess the presence of right-to-left shunting (RLS) in patients with obstructive sleep apnea (OSA), and compare clinical characteristics and parameters of the sleep studies of patients with and without RLS.

BACKGROUND

The most common cause of RLS is due to intermittent flow through a patent foramen ovale (PFO). PFO occurs more frequently in patients with OSA and may be involved in the exacerbation of OSA.

METHODS

Patients with an abnormal polysomnogram seen at UCLA-Santa Monica Sleep Medicine Clinic were enrolled. A diagnosis of RLS was made using a transcranial Doppler (TCD) bubble study. Gender and age-matched controls were drawn from patients referred for cardiac catheterization who underwent a TCD. The frequency of RLS in OSA patients and the controls was evaluated. Clinical characteristics and polysomnogram parameters were compared between OSA patients with and without a RLS.

RESULTS

A total of 100 OSA patients and 200 controls participated in the study. The prevalence of RLS was higher in patients with OSA compared to the control group (42% versus 19%; p < 0.0001). Patients with OSA and a RLS had a lower apnea-hypopnea index (AHI), less obstructive apnea, and fewer hypopnea episodes than patients with OSA without a RLS. The baseline and nadir SpO2 were similar in both groups and did not correlate with the level of RLS assessed by TCD. The degree of desaturation for a given respiratory disturbance, as measured by oxygen desaturation index (ODI)/AHI ratio, was higher in OSA patients with RLS versus OSA patients without RLS (0.85 ± 0.07 versus 0.68 ± 0.04; p < 0.0001).

CONCLUSION

RLS, most commonly due to a PFO, occurs 2.2 times more frequently in OSA patients compared to a control population that was matched for age and gender. The severity of sleep apnea is not greater in OSA patients who have a PFO. However, patients with OSA and a PFO are more likely to become symptomatic at a younger age with an equivalent decrease in nocturnal SpO2, and have greater arterial desaturation in proportion to the frequency of respiratory disturbances.

Clinical Performance of the New Gore Septal Occluder in Patent Foramen Ovale Closure: A Single-Center Experience

BACKGROUND

Several progressively refined percutaneous devices for patent foramen ovale (PFO) closure have been recently developed. We describe our single-center experience with the new Gore septal occluder (GSO).

METHODS

Between January 2012 and May 2013, all consecutive patients with a PFO and previous cerebral thromboembolic events underwent percutaneous closure with the GSO system. Device implantation was performed under local anesthesia with combined fluoroscopic and intracardiac echographic monitoring. Follow-up schedule was: transthoracic echo at day 1 and day 30, as well as transcranial Doppler at 6 months and 12 months, all with clinical concomitant evaluation.

RESULTS

Twenty-two patients (11 males and 11 females) with a mean age of 51.2 ± 13.9 years (range, 40-74 years) had PFO closure. At baseline, 4 and 18 subjects had medium-grade and large-grade right to left permanent shunt, respectively; isolated PFO was present in 13 patients and PFO with atrial septal aneurysm was present in 9 patients. Device placement was successful in all patients. Median procedural and fluoroscopic times were 40.5 minutes (range, 22-92 minutes) and 6.5 minutes (range, 3-16 minutes), respectively. Clinical and instrumental follow-up data were obtained at 12 months in 22 patients (100%). A low-grade (<5 microbubbles) permanent residual shunt was registered in 5 patients at 6 months and in 2 patients (during Valsalva only) at 12-month follow-up. Functional PFO occlusion was thus obtained in all patients.

CONCLUSION

This single-center initial experience suggests that the GSO is a safe and effective closure device, straightforward to implant with quick deployment and minimal imaging, and suitable for a range of atrial septal anatomies. Incidence and entity of residual shunts at follow-up were consistent with functional PFO occlusion in all patients.

Pathophysiology of inner ear decompression sickness: potential role of the persistent foramen ovale

Inner-ear decompression sickness (inner ear DCS) may occur in isolation ('pure' inner-ear DCS), or as part of a multisystem DCS presentation. Symptoms may develop during decompression from deep, mixed-gas dives or after surfacing from recreational air dives. Modelling of inner-ear inert gas kinetics suggests that onset during decompression results from supersaturation of the inner-ear tissue and in-situ bubble formation. This supersaturation may be augmented by inert gas counterdiffusion following helium to nitrogen gas switches, but such switches are unlikely, of themselves, to precipitate inner-ear DCS. Presentations after surfacing from air dives are frequently the 'pure' form of inner ear DCS with short symptom latency following dives to moderate depth, and the vestibular end organ appears more vulnerable than is the cochlea. A large right-to-left shunt (usually a persistent foramen ovale) is found in a disproportionate number of cases, suggesting that shunted venous gas emboli (VGE) cause injury to the inner-ear. However, this seems an incomplete explanation for the relationship between inner-ear DCS and right-to-left shunt. The brain must concomitantly be exposed to larger numbers of VGE, yet inner-ear DCS frequently occurs in the absence of cerebral symptoms. This may be explained by slower inert gas washout in the inner ear than in the brain. Thus, there is a window after surfacing within which VGE arriving in the inner-ear (but not the brain) would grow due to inward diffusion of supersaturated inert gas. A similar difference in gas kinetics may explain the different susceptibilities of cochlear and vestibular tissue within the inner-ear itself. The cochlea has greater perfusion and a smaller tissue volume, implying faster inert gas washout. It may be susceptible to injury by incoming arterial bubbles for a shorter time after surfacing than the vestibular organ.

Effect of body position and oxygen tension on foramen ovale recruitment

While there is an increased prevalence of stroke at altitude in individuals who are considered to be low risk for thrombotic events, it is uncertain how venous thrombi reach the brain. The patent foramen ovale (PFO) is a recruitable intracardiac shunt between the right and left atrium. We aimed to determine whether body position and oxygen tension affect blood flow through the PFO in healthy adults. We hypothesized that hypoxia and body positions that promote right atrial filling would independently recruit the PFO. Subjects with a PFO (n = 11) performed 11 trials, combining four different fractions of inhaled oxygen (FiO₂) (1.0, 0.21, 0.15, and 0.10) and three positions (upright, supine, and 45° head down), with the exception of FiO₂ = 0.10, while 45° head down. After 5 min in each position, breathing the prescribed oxygen tension, saline bubbles were injected into an antecubital vein and a four-chamber echocardiogram was obtained to evaluate PFO recruitment. We observed a high incidence of PFO recruitment in all conditions, with increased recruitment in response to severe hypoxia and some contribution of body position at moderate levels of hypoxia. We suspect that increased pulmonary vascular pressure, secondary to hypoxia-induced pulmonary vasoconstriction, increased right atrial pressure enough to recruit the PFO. Additionally, we hypothesize that the minor increase in breathing resistance that was added by the mouthpiece, used during experimental trials, affected intrathoracic pressure and venous return sufficiently to recruit the PFO.

Current status of percutaneous PFO closure

The clinical significance of persistent patent foramen ovale (PFO) is not well defined. Empirically, PFO has been associated with many clinical conditions. In cryptogenic stroke, migraine, and orthodeoxia/platypnea, a plausible biologic mechanism exists to support PFO closure as a possible treatment. Although transcatheter closure of PFO has been available for over 2 decades, it has remained controversial due to a paucity of evidence to guide patient and device selection. Contemporary studies investigating PFO closure as treatment for patients with these conditions have been published recently and longitudinal data regarding the safety and efficacy of the devices is now available. In this review, we aim to describe the potential clinical significance of a patent foramen in the adult, appraise the newest additions to the body of evidence, and discuss the safety, benefit, patient selection, and future of transcatheter treatment of PFO.

Magnetic resonance assessment of pulmonary (QP) to systemic (QS) flows using 4D phase-contrast imaging: pilot study comparison with standard through-plane 2D phase-contrast imaging

RATIONALE AND OBJECTIVES

To investigate four-dimensional (4D) phase-contrast (PC) magnetic resonance (MR) in the evaluation of intracardiac shunts by simultaneous assessment of pulmonary (QP) and systemic (QS) flows in a pilot study and to compare results to through-plane two-dimensional (2D) PC MR.

MATERIALS AND METHODS

Institutional review board approval and written informed consent were obtained. Nineteen patients with suspected intracardiac shunts underwent cardiac MR at 1.5T. Assessments of QP and QS were performed using free-breathing retrospectively gated 2D PC gradient recalled echo (GRE; 1.6 × 1.6 × 5 mm(3)) imaging with one-dimensional through-plane velocity encoding gradient (venc = 150 cm/s) in consecutive measurements for the main pulmonary artery (MPA) and ascending aorta (AA), respectively. A prospectively triggered 4D PC GRE technique (2.4 × 1.8 × 3 mm(3)) with three orthogonal venc directions was also used with volume coverage of both MPA and AA.

RESULTS

QP and QS assessed by 4D PC correlated with 2D PC acquisitions (r = 0.92 and r = 0.67 respectively; P < .0001 for both) but demonstrated significant underestimation of individual flow volumes (-21.9 ± 12.2 mL; P < .0001 and -10.7 ± 13.1 mL; P = .0023, respectively). Calculated QP:QS ratios demonstrated high correlation (r = 0.78; P < .0001) and no significant differences between 4D PC and 2D PC acquisitions (-0.09 ± 0.24, P = .14). Image acquisition times for 2D PC assessment of QP and QS were 2.98 ± 0.52 and 2.84 ± 0.50 minutes, respectively (P = .038), whereas time to acquire 4D PC images was significantly longer, 18.75 ± 4.58 minutes (P < .001).

CONCLUSIONS

Four-dimensional PC MR imaging allows for accurate assessment of QP:QS ratios in the evaluation of intracardiac shunts while absolute flow volumes demonstrate offsets. Further refinement of the technique with improvement in acquisition times may be required before widespread clinical implementation.

Hypoxemia in the setting of right to left shunting through patent foramen ovale without pulmonary hypertension

Patent foramen ovale is often seen in the population but rarely observed with right to left shunting in the absence of pulmonary hypertension. Our report describes such a case where a patient with progressive shortness of breath had resolution of symptoms upon percutaneous closure. A discussion of the case and relation to similar cases is presented. A literature review along with explanation of possible contributing mechanisms in our patient's situation is explained. We also discuss several implications for practice and suggest that percutaneous closure is effective in our case and in similar situations.

Resting pulmonary haemodynamics and shunting: a comparison of sea-level inhabitants to high altitude Sherpas

The incidence of blood flow through intracardiac shunt and intrapulmonary arteriovenous anastomoses (IPAVA) may differ between Sherpas permanently residing at high altitude (HA) and sea-level (SL) inhabitants as a result of evolutionary pressure to improve gas exchange and/or resting pulmonary haemodynamics. To test this hypothesis we compared sea-level inhabitants at SL (SL-SL; n = 17), during acute isocapnic hypoxia (SL-HX; n = 7) and following 3 weeks at 5050 m (SL-HA; n = 8 non-PFO subjects) to Sherpas at 5050 m (n = 14). SpO2, heart rate, pulmonary artery systolic pressure (PASP) and cardiac index (Qi) were measured during 5 min of room air breathing at SL and HA, during 20 min of isocapnic hypoxia (SL-HX; PETO2 = 47 mmHg) and during 5 min of hyperoxia (FIO2 = 1.0; Sherpas only). Intracardiac shunt and IPAVA blood flow was evaluated by agitated saline contrast echocardiography. Although PASP was similar between groups at HA (Sherpas: 30.0 ± 6.0 mmHg; SL-HA: 32.7 ± 4.2 mmHg; P = 0.27), it was greater than SL-SL (19.4 ± 2.1 mmHg; P < 0.001). The proportion of subjects with intracardiac shunt was similar between groups (SL-SL: 41%; Sherpas: 50%). In the remaining subjects, IPAVA blood flow was found in 100% of subjects during acute isocapnic hypoxia at SL, but in only 4 of 7 Sherpas and 1 of 8 SL-HA subjects at rest. In conclusion, differences in resting pulmonary vascular regulation, intracardiac shunt and IPAVA blood flow do not appear to account for any adaptation to HA in Sherpas. Despite elevated pulmonary pressures and profound hypoxaemia, IPAVA blood flow in all subjects at HA was lower than expected compared to acute normobaric hypoxia.

Patent foramen ovale closure in the treatment of obstructive sleep apnea

Obstructive sleep apnea (OSA) and patent foramen ovale (PFO) are common conditions and may coexist. In patients with OSA, increases in right-to-left shunting across a PFO may result in increased burden of hypoxia, although the effect of this is unknown. We report the cases of 3 patients with highly symptomatic OSA and PFO who underwent percutaneous closure with the Coherex FlatStent PFO Closure System. Although PFO closure can be achieved with minimally invasive techniques and low rates of adverse events, its importance in reducing hypoxia in this population is unknown. PFO closure may result in improvement in apneas and symptoms in selected OSA patients and may impact cardiovascular events in this group through hypoxia-mediated or other unrecognized mechanisms.

Premature closure or restriction of the foramen ovale: prenatal diagnosis by directional enhanced flow imaging

Premature closure or restriction of the foramen ovale may occur at any time during pregnancy and may be due to various causes. We describe 2 patients with premature closure or restriction of the foramen ovale during the third trimester. In both patients the foramen ovale was detected by directional enhanced flow imaging technology (DeFLOW; Hitachi-Aloka Medical, Ltd, Tokyo, Japan), a novel method of imaging blood flow dynamics. Our findings indicate that D-eFLOW can display blood flow information with higher sensitivity and resolution than conventional methods, helping obstetricians and pregnant women make timely decisions about delivery.

Type A aortic dissection complicated with fistulization into the right atrium and right-to-left shunt

Fistulization between the aorta and the right atrium is a rare complication of ascending aortic dissection. Because of the typical haemodynamic unstability, the diagnosis is often made by bedside or intraoperative transoesophageal echocardiography. The treatment is surgical, but with very high mortality. We describe a case of type A aortic dissection complicated with shock and fistulization into the right atrium with the right-to-left shunt through a patent foramen ovale. Surgical repair was successful.

Comorbidity in perimenstrual migraine

Comorbidity may be defined as the association of two or more diseases in individuals at a frequency greater than that expected statistically by chance. Studying the co-occurrence of two disorders requires a careful statistical analysis before any clear conclusion on causality is reached. Many studies have looked for an association between migraine and many diseases, reporting several sometimes controversial comorbidities in migraine subjects. Although migraine is more common in women than in men, very few studies have analyzed the comorbidity of perimenstrual migraine, a migraine sub-type characterized by attacks of migraine without aura related to menstruation. We review the studies on migraine comorbidities, particularly migraine without aura in women.

[Chronic migraine: pathophysiology]

Chronic migraine is considered a complication of episodic migraine. Several risk factors, which may be modifiable or non-modifiable, make varying contributions to the progression towards chronification. Every year 2.5% of patients with episodic migraine go on to suffer chronic migraine. Experimental studies point to a dysfunction in the descending pain modulatory system that would facilitate nociceptive afferents, in the absence of damage to tissues, and so chronic migraine would share a pathogenesis that is similar to that of fibromyalgia, irritable bowel syndrome or chronic tension-type headache (conditions that frequently coexist). This paper reviews the risk factors and the scientific evidence of the possible pathogenic mechanisms involved in the progression towards chronification.

[Stroke. are there any difference between patients with or without patent foramen ovale in left atrial appendage systolic function?]

INTRODUCTION

The aim of this study was to evaluate the systolic function of the left atrial appendage (LAA) in a group with and without patent foramen ovale (PFO) who suffered ischemic cerebrovascular events.

MATERIAL AND METHODS

Between September 2010 and October 2011, 17 patients were referred for transesophageal echocardiography (TEE) after suffering a stroke. PFO was defined as the passage of at least one bubble through atrial septum with bubble test. We compared systolic velocity in the appendage between patients with and without PFO and a control group.

RESULTS

Were 8 women and 9 men, mean age 54.1 ± 19.5 years and 8 patients were under 55 years of age. All patients had suffered a ischemic cerebrovascular events, 41.2% had stroke, 52.9% transient ischemic attack and amaurosis fugax 5.9%. In the assessment of TEE, 11.8% had atrial septal aneurysm and 35.3% PFO. Mean LAA systolic velocity was 66.3 ± 20.3 cm / sec. There was no difference in systolic velocity of the LAA between patients with and without PFO (67.5 ± 11.8 cm / sec vs 65.7 ± 24.3 cm / sec respectively, p = 0.87). The control group of 8 patients, 5 women and 3 men, mean age 39.5 ± 18 years, had a LAA systolic velocity of 77.6 ± 28.9 cm / sec, no significant differences with ischemic patients.

CONCLUSION

There were no differences in systolic function of the LAA between patients with and without PFO with ischemic cerebrovascular event.

Platypnoea-orthodeoxia syndrome

A 78-year-old man with a history of gastric ulcer and pulmonary embolism was admitted for elective revision of a right total hip replacement. He was mildly hypoxic preoperatively (saturation 89% on air). He became profoundly breathless postoperatively (saturation 75%). He was treated for presumed pulmonary oedema but failed to improve. A CT pulmonary angiogram and transthoracic echo showed no clear cause for his symptoms. Because the patient's symptoms were postural, exacerbated in the upright position and relieved by lying supine, the authors suspected a diagnosis of platypnoea-orthodeoxia syndrome associated with a patent foramen ovale (PFO). Transoesophageal echo and microbubble study confirmed he had a PFO. The patient's PFO was percutaneously closed and his symptoms and positional hypoxia completely resolved.

Regional cardiac tamponade resulting in hypoxia from acute right to left inter-atrial shunting

Loculated pericardial effusion, as a cause of acute hypoxia, is an unusual finding. Here, we describe the case of a patient who underwent percutaneous coronary intervention, complicated by a localized pericardial hematoma compressing the right atrium, resulting in right to left shunting of blood through a patent foramen ovale and subsequent hypoxia. Evacuation of the hematoma was eventually performed via a pericardial window with resolution of hypoxia.

Higher LA pressure may prevent opening of patent foramen ovale in acute ischemic stroke patients with atrial fibrillation

BACKGROUND AND PURPOSE

Detection rate of right-to-left shunt (RLS) may be lower in stroke patients with atrial fibrillation (AF) than in those without AF. This may be due to the mechanism of embolic stroke in AF patients that involves cardiac embolus rather than paradoxical embolism due to RLS. Patients with AF frequently have subclinical heart failure, resulting in elevated left atrial (LA) pressure, which may prevent opening of a patent foramen ovale (PFO). We aimed to investigate whether the detection rate of RLS in stroke patients with AF was affected by elevated LA pressure.

METHOD

We enrolled consecutive acute stroke patients with AF and, as controls, consecutive acute stroke patients without AF. RLS was diagnosed using contrast transcranial Doppler. To assess LA pressure, the ratio of early mitral inflow velocity to diastolic mitral annular velocity (E/E') was measured using transthoracic echocardiography.

RESULT

We enrolled 171 patients with AF (AF group, age, 78 years [IQR, 70-83]) and 171 patients without AF (control group, age, 73 years [IQR, 64-81]). RLS was observed less frequently in AF patients than in the control group (9% vs. 18%, p=0.024). E/E' ratio was higher in AF patients (13.1 [9.4-17.4] vs. 10.9 [8.2-13.7], p<0.001). Among controls, E/E' ratio did not differ between patients with and without RLS (11.8 [8.5-12.9] vs. 10.8 [8.0-13.9], p=0.884). Conversely, in AF patients, E/E' ratio was lower in patients with RLS than in those without RLS (9.0 [8.3-12.6] vs. 13.6 [10.2-18.1], p=0.008). Multivariate regression analysis demonstrated that E/E' ratio of <11.0 was an independently associated with RLS (OR 4.61, 95%CI 1.21-17.62, p=0.025).

CONCLUSION

RLS was detected less frequently in AF patients than in controls. Elevated LA pressure was associated with the absence of RLS in AF stroke patients and may prevent opening of a PFO.

Patent foramen ovale: thromboembolic structure or incidental finding?

A patent foramen ovale (PFO) is identified in approximately 27% of healthy individuals undergoing routine autopsy and in 25% of the general population on transesophageal echocardiography (TEE). PFO generally considered benign, but has been associated with stroke, migraine and diving decompression sickness. We searched Pubmed for English language articles that examined the relationship of PFO to vascular events. PFOs are highly prevalent in patients with cryptogenic stroke and in patients with migraine, but the incidence of primary and recurrent stroke does not seem to be increased in patients with PFO. Consequently, neither anticoagulation nor antiplatelet drugs are recommended in asymptomatic patients lacking other indications for anticoagulation. In symptomatic patients with PFO, current guidelines consider antiplatelet medications as treatment of choice for cerebrovascular events. There is no strong evidence that supports routine closure of PFO in patients with stroke or migraine although some patients with combined characteristics of PFO might benefit from closure. In conclusion, this review suggests that PFO is not an established risk factor for stroke even in the young population with recurrent cryptogenic stroke.

[Patent foramen ovale and migraine: a causal or casual relationship?]

The occlusion of a patent foramen ovale (PFO) is one of the most promising and controversial issues of interventional cardiology, with an increasing number of procedures, indications and scientific publications. Although this procedure is considered relatively feasible and efficacious, complications may occur, and the balance between risks and benefits is not always favorable. Data on long-term safety and efficacy are also lacking. From cryptogenic stroke in young patients, indications for occlusion have been extended to include patients with drug-refractory migraine. In this setting, the prevalence of PFO is higher than in the general population, suggesting a possible pathogenetic role. Pathophysiology of this condition and evidence to support occlusion of PFO are incomplete, but a trend towards improving has been reported in many retrospective studies. The only randomized study for migraine benefits in PFO occlusion (MIST) has failed to show a reduction in frequency and intensity of attacks. Selection criteria for patients who will most probably benefit from occlusion are needed. The aim of this brief analysis is to focus the pathophysiological and diagnostic issues on migraine, evaluate their relation with PFO, and review studies to outline percutaneous closure indications.

Patent foramen ovale, systemic embolization, and closure

Patent foramen ovale has become the subject of increasing interest in modern cardiovascular disease. This has been the result of several factors including, among others, description of paradoxical embolism, documentation of patent foramen ovale with right to left shunt, the rather ubiquitous use of echocardiography, the issue of stroke prevention, and more recently, the relationship between patent foramen ovale and migraine.

[Comparative clinical and anatomic characteristic of patients with patent foramen ovale in cryptogenic and noncryptogenic stroke]

In order to study anatomical and functional characteristics of patent foramen ovale (PFO) in patients with cryptogenic stroke and with other stroke subtypes we examined 56 stroke patients (male--35, female--21, age 46.7 +/- 16.5 years) with PFO and ischemic stroke. Diagnosis of PFO was made by transesophageal echocardiography (TEE), contrast transcranial Doppler monitoring (C-TCD), contrast transthoracic echocardiography (C-TTE). Group 1 was made up of patients with definite stroke cause (cardioembolic, lacunar, atherotrombotic) (n=40), and group 2--of patients with cryptogenic stroke (n=16). Patients in group 2 were younger than patients in group 1 (38.7 +/- 13.4 and 50.4 +/- 16.5 years, p < 0.05) and had slight neurological symptoms. These patients also more frequently had avalvular, or "window-like" anatomic types of PFO (2 [13%] and 4 [27%] patients, respectively), combination of large anatomic size (3 mm and larger) and functional level of PFO (3 degree of the right-to-left shunt by C-TCD) (p < 0.05).