Computational Flow Dynamic Analysis of Right and Left Atria in Patent Foramen Ovale: Potential Links with Atrial Fibrillation

Feasibility and safety of cryoballoon ablation for atrial fibrillation and closing patent foramen ovale without implantation：A pilot study

BACKGROUND

Patent foramen ovale (PFO) affects 20%-34% of adults and is associated with strokes and other disorders. The conventional treatment of PFO-related strokes is a closure procedure. The metal device is associated with some adverse events.

OBJECTIVE

Our aim was to investigate the efficacy and safety of PFO closure using cryoablation without implantation in patients with atrial fibrillation (AF) who underwent pulmonary vein isolation (PVI).

METHODS

We divided the 22 patients with both PFO and AF who underwent PVI via cryoablation into 2 groups: standard PVI + atrial septal (AS) cryoablation group (group 1, n = 11) and standard PVI group (group 2, n = 11). The guidewire accesses the left atrium through the PFO without AS puncture during the procedure. Standard PVI via cryoablation was performed. The cryoballoon was retracted to the right atrium and inflated against the AS post-PVI. Patients in group 1 had cryoablation for 120-150 seconds, whereas patients in group 2 received sham ablation. The co-primary end points were the PFO closure rate and a composite of AF recurrence and stroke/transient ischemic attack (TIA) events.

RESULTS

There were no differences in procedure-related adverse events between the 2 groups. Neither group had an ischemic stroke report at 1-year follow-up. The PFO closure rate at 6 months in group 1 was significantly higher than that in group 2 (7 [63.6%] vs 1 [9.1%]; P = .002). AF recurrence post ablation was comparable in both groups at 3 months (3 [27.3%] vs 1 [9.1%]; P = .269), 6 months (0 vs 0), and 12 months (2 [18.2%%] vs 1 [9.1%]; P = .534) of follow-up.

CONCLUSION

Cryoablation is a safe and effective approach to close PFO in patients with AF undergoing PVI in a single procedure.

Long-term impact of transcatheter closure interatrial shunts on disabling migraine

BACKGROUNDS

Effectiveness of patent foramen ovale (PFO) closure on relief of migraine, is still unclear. We sought to analyse the long-term (>10 years) effects of interatrial septal shunt repair on disabling migraine performing a retrospective non-randomised study.

METHODS

Clinical records of patients with disabling, medication-refractory migraine and PFO or significant ASD referred to our centre for closure from 2006 to 2018, were analysed.

RESULTS

Forty -six patients (38 female, mean age 40.0 ± 3.7 years) with PFO and 32 patients with significant ASD (28 female, mean age 38.0 ± 4.1 years) submitted to transcatheter closure had a pre-existing disabling migraine with mean Migraine Disability Assessment Score (MIDAS) of 35.8 ± 4.7. After a mean follow-up of 118.2 ± 19.1 months (range 96 to 144), 72 out of 78 patients were still followed-up: in all subjects, aura was abolished, and migraine improved also in patients without aura. The mean MIDAS significantly decreased from baseline value (p < 0.01). Complete migraine resolution was associated in PFO patients with a shorter history of migraine, a more severe thrombophilic profile, a more severe Right-to-Left Shunt (RLS) and larger left atrial diameter and volume, and in ASD patients with bidirectional shunt.

CONCLUSIONS

Device-based repair of PFO/ASD in patients with migraine was associated with abolition of aura and symptoms reduction in the long-term period.

Atrial septal aneurysm contribution to the risk of cryptogenic stroke in patients with patent foramen ovale: A brief updated systematic review and meta-analysis

Atrial septal aneurysms (ASA) play an important role in cryptogenic stroke (CS) in patients with patent foramen ovale (PFO) but its contribution remains still not fully clarified in current literature. We sought to evaluate the contribution of ASA to the risk of CS in PFO patients based on studies published so far by means of a systematic review and metanalysis. A literature search, based on PubMed, Google Scholar and EMBASE databases, was performed to locate articles, published English language between 2000 and 2021, analysing the relationship between ASA and CS. The final research was conducted in September 2021. A total of 577 articles were retrieved after excluding duplicates. The initial screening excluded 215 articles because they did not meet inclusion criteria, leaving 362 articles to assess for eligibility. Subsequently, after evaluation of the full-text articles, 354 were excluded and 8 investigations met the inclusion criteria. Overall, 822 patients (mean age 48.3 years) were enrolled in the reviewed manuscripts with a prevalence of males of 48.7% and a normal distribution of the classical cardiovascular risk factors. ASA was present in 25.3% (208 subjects) of the patients enrolled, while the association of PFO+ASA was observed in 24.3% (200 subjects) of patients enrolled. PFO Patients with ASA were at higher risk of CS compared to those without (odd ratio: 3.38, 95% CI: 2.72-5.51, p<0.001, I2=4.3%,). The relative funnel plot did not show any evident asymmetry, confirming absence of publication bias. Our updated metanalysis enhances the importance of ASA contribution to stroke in patients with patent foramen ovale, being present in a third of patients with symptomatic PFO to whom it confers an additional odd ratio of 3.38.

Recent progress in patent foramen ovale and related neurological diseases: A narrative review

Patent foramen ovale (PFO) is a common congenital cardiac abnormality when the opening of the interatrial septum is not closed in adulthood. This abnormality affects 25% of the general population. With the development of precision medicine, an increasing number of clinical studies have reported that PFO is closely related to various neurological diseases such as stroke, migraine, obstructive sleep apnea, and decompression syndrome. It has also been suggested that PFO closure could be effective for preventing and treating these neurological diseases. Therefore, increasing attention has been given to the prevention, diagnosis, and treatment of PFO-related neurological diseases. By reviewing existing literature, this article focuses on the pathogenesis, epidemiology, and clinical characteristics of PFO-related neurological diseases, as well as the prevention and treatment of different neurological diseases to discuss, and aims to provide current progress for this field and decision-making evidence for clinical practice.

Increased Blood Residence Time as Markers of High-Risk Patent Foramen Ovale

Previous investigations have suggested that patients with patent foramen ovale (PFO) often have an atrial dysfunction, like to that observed in patients with atrial fibrillation (AF) which may concur to an increased risk of cryptogenic stroke. The aim of the study is to compare the atrial resident time (Rt) of PFO patients to those with sinus rhythm (SR) and AF using patient-specific 3D computational fluid dynamics (CFD) analysis. Models of left atrium (LA) hemodynamics were obtained from time-resolved CT scans and transthoracic echocardiography (TTE). Enrolled patients were divided into three groups: 30 healthy subjects with SR, 30 with PFO, and 30 with AF without PFO. Blood stasis was evaluated by determining the blood residence time (Rt) distribution in the LA and left atrial appendage (LAA). Overall, 90 patients (mean age 47.4 ± 7.5 years, 51 males) were included into the analysis. PFO patients exhibit higher mean Rt values compared to healthy subjects (2.65 ± 0.2 vs 1.5 ± 0.2 s). Conversely, AF patients presented higher Rt when compared to PFO patients (2.9 ± 0.3 vs 2.3 ± 0.2 s). Moreover, PFO patients presenting cerebral lesions at magnetic resonance imaging have a higher Rt compared to those without (2.9 ± 0.3 vs 2.3 ± 0.2 s, respectively, p < 0.001). PFO patients have a higher degree of atrial Rt compared to healthy subjects similar to that observed in AF patients. The higher mean LA Rt values offer an insight into the pathophysiological mechanism linking PFO with cryptogenic stroke and might be a marker of high-risk PFOs.

Applications of computational fluid dynamics to congenital heart diseases: a practical review for cardiovascular professionals

INTRODUCTION

The increased survival rate of patients with congenital heart disease (CHD) has made it likely that 70%-95% of infants with CHDs surviving into adulthood often require careful follow-up and (repeat) interventions. Patients with CHDs often have abnormal blood flow patterns, due to both primary cardiac defect and the consequent surgical or endovascular repair.

AREA COVERED

Computational fluid dynamics (CFD) alone or coupled with advanced imaging tools can assess blood flow patterns of CHDs to both understand their pathophysiology and anticipate the results of surgical or interventional repair.

EXPERT OPINION

CFD is a mathematical technique that quantifies and describes the characteristics of fluid flow using the laws of physics. Through dedicated software based on virtual reconstruction and simulation and patients' real data coming from computed tomography, magnetic resonance imaging, and 3/4 D-ultrasound, reconstruction of models of circulation of most CHD can be accomplished. CFD can provide insights about the pathophysiology of coronary artery anomalies, interatrial shunts, coarctation of the aorta and aortic bicuspid valve, tetralogy of Fallot and univentricular heart, with the capability in some cases of simulating different types of surgical or interventional repair and tailoring the treatment on the basis of these findings.

Right atrium and cryptogenic ischaemic stroke in the young: a case-control study

Background

Recent studies suggest left atrial (LA) dysfunction in cryptogenic stroke. We studied the dynamics of right atrium (RA) and right atrial appendage (RAA) in young adults with cryptogenic stroke. We hypothesised that bi-atrial dysfunction and blood stagnation might contribute to thrombosis formation in patients with patent foramen ovale (PFO), as deep venous thrombosis is detected only in the minority of patients.

Methods

Thirty patients (aged 18–49) with a first-ever cryptogenic stroke and 30 age-matched and sex-matched stroke-free controls underwent cardiac magnetic resonance (CMR) imaging. An approach to estimate the RAA volume was developed, using crista terminalis and pectinate muscles as anatomical landmarks. Atrial expansion indices were calculated as (maximal volume – minimal volume) ×100%/minimal volume. Total pulmonary to systemic blood flow ratio (Qp/Qs) was based on phase contrast CMR. Right-to-left shunt (RLS) was evaluated with transoesophageal echocardiography in 29 patients and transcranial Doppler in 30 controls, moderate-to-severe RLS considered as clinically significant.

Results

We found that RA and RAA volumes were similar between patients and controls. Also, RA expansion index was similar, but RAA (95.6%±21.6% vs 108.7%±25.8%, p=0.026) and LA (126.2%±28% vs 144.9%±36.3%, p=0.023) expansion indices were lower in patients compared with controls. Seven (24%) of 29 patients had an RLS compared with 1 (3%) of 30 controls (p=0.012). Among 59 study subjects, RLS was associated with lower RA (81.9%±15.9% vs 98.5%±29.5%, p=0.030), RAA (84.7%±18% vs 105.6%±24.1%, p=0.022), LA (109.8%±18.6% vs 140.1%±33.7%, p=0.017) and LAA (median 102.9% (IQR 65.6%–121.7%) vs 229.1% (151.8%–337.5%], p=0.002) expansion indices and lower Qp/Qs ratio (0.91±0.06 vs 0.98±0.07, p=0.027).

Conclusions

This study suggests bi-atrial dysfunction in young adults with cryptogenic stroke, associated with moderate-to-severe RLS. Dysfunction of the atria and atrial appendages may be an additional mechanism for PFO-related stroke.

Trial registration number

NCT01934725.

Computational fluid dynamics of the right atrium: Assessment of modelling criteria for the evaluation of dialysis catheters

Central venous catheters are widely used in haemodialysis therapy, having to respect design requirements for appropriate performance. These are placed within the right atrium (RA); however, there is no prior computational study assessing different catheter designs while mimicking their native environment. Here, a computational fluid dynamics model of the RA, based on realistic geometry and transient physiological boundary conditions, was developed and validated. Symmetric, split and step catheter designs were virtually placed in the RA and their performance was evaluated by: assessing their interaction with the RA haemodynamic environment through prediction of flow vorticity and wall shear stress (WSS) magnitudes (1); and quantifying recirculation and tip shear stress (2). Haemodynamic predictions from our RA model showed good agreement with the literature. Catheter placement in the RA increased average vorticity, which could indicate alterations of normal blood flow, and altered WSS magnitudes and distribution, which could indicate changes in tissue mechanical properties. All designs had recirculation and elevated shear stress values, which can induce platelet activation and subsequently thrombosis. The symmetric design, however, had the lowest associated values (best performance), while step design catheters working in reverse mode were associated with worsened performance. Different tip placements also impacted on catheter performance. Our findings suggest that using a realistically anatomical RA model to study catheter performance and interaction with the haemodynamic environment is crucial, and that care needs to be given to correct tip placement within the RA for improved recirculation percentages and diminished shear stress values.

Patent Foramen Ovale in Cryptogenic Ischemic Stroke: Direct Cause, Risk Factor, or Incidental Finding?

Patent foramen ovale (PFO) has been associated with cryptogenic stroke. There is conflicting data and it remains uncertain whether PFO is the direct cause, a risk factor or an incidental finding. Potential stroke mechanisms include paradoxical embolism from a venous clot which traverses the PFO, in situ clot formation within the PFO, and atrial arrhythmias due to electrical signaling disruption. Main risk factors linked with PFO-attributable strokes are young age, PFO size, right-to-left shunt degree, PFO morphology, presence of atrial septal aneurysm, intrinsic coagulation-anticoagulation systems imbalance, and co-existence of other atrial abnormalities, such as right atrial septal pouch, Eustachian valve and Chiari's network. These may act independently or synergistically, multiplying the risk of embolic events. The RoPE score, a scale that includes factors such as young age, cortical infarct location and absence of traditional stroke risk factors, is associated with the probability of a PFO being pathogenic and stroke recurrence risk after the index stroke. Multiple investigators have attempted to correlate other PFO features with the risk of PFO-related stroke, but further investigation is needed before any robust conclusions are reached. PFO presence in young patients with cryptogenic stroke should be considered as etiologically suspect. Caution should be exercised in interpreting the relevance of other PFO features.