Patent foramen ovale diameter and embolic stroke: a part of the puzzle?

Transcatheter closure of PFO as secondary prevention of cryptogenic stroke

This article covers the main unsolved issues regarding the potential role that the patent foramen ovale (PFO) plays in the genesis of so-called cryptogenic stroke. Some brief notions of the anatomy and epidemiology of the PFO are outlined. Subsequently, the results of the three trials on secondary prevention (medical therapy vs. transcatheter closure) in patients with PFO and a history of cryptogenic stroke are presented. The conflicting results of numerous meta-analyses derived from the three randomized controlled trials are discussed. Official scientific guidelines dispute an alleged superior efficacy of transcatheter PFO occlusion in comparison with antithrombotic therapy alone (anticoagulants or antiplatelet agents), except for selected cases of patients with documented PFO and a concomitant clinical-instrumental picture of deep venous thrombosis. Nevertheless, considering recent doubts about the presumptive thrombogenic and arrhythmogenic potential of PFO occlusion, which concerns only one of the septal occluders previously used, further in-depth investigations are warranted, centered on the use of newer dedicated devices to be tested in comparison with antithrombotic regimens alone.

Unresolved or Contradictory Issues About Management of Patients With Patent Foramen Ovale and Previous Cryptogenic Stroke: Additional Randomized Controlled Trials Are Eagerly Awaited

Stating a well-codified and widely accepted therapeutic conduct for patients with patent foramen ovale (PFO) and previous cryptogenic stroke is made difficult and somewhat controversial by several issues remained unresolved so far. In this short review, some aspects of the possible role played by the PFO in the pathogenesis of cryptogenic stroke are succinctly analyzed. First, some aspects of cardiovascular anatomy of the human fetus and the adult are outlined. Subsequently, the three randomized controlled trials (RCTs) that have been accomplished so far to compare the implant of a transeptal occluding device with a simple medical therapy in patients with PFO and history of cryptogenic stroke are briefly examined. These RCTs, when assessed using the “intention to treat” method, do not show a greater protective effect of therapy with transeptal device as regards the recurrences of stroke. Afterwards, there is a brief presentation of the findings of several meta-analyses that have been derived from the three above mentioned RCTs, whose results are strikingly discordant with each other. In fact, some of them come to the conclusion that the transcatheter closure of PFO does not offer significant advantages compared to antithrombotic therapy for the secondary prevention of cryptogenic stroke, while others based on subgroup analyses argue that the transcatheter closure of PFO with Amplatzer device, differently from the one performed using the STARFlex device, would be associated with significantly lower incidence of cerebrovascular events compared with medical therapy alone. Finally, the authors argue the need to adhere to the current scientific guidelines. They substantially deny an alleged superior efficacy of transcatheter PFO occlusion compared to medical therapy with antithrombotic agents (anticoagulants or antiplatelet agents), except for selected cases of patients with documented PFO and concomitant clinical-instrumental picture of deep venous thrombosis.

Leptin receptor action and mechanisms of leptin resistance

The adipose tissue-derived hormone leptin regulates energy balance and neuroendocrine function. Resistance to the appetite-suppressing effects of leptin is associated with common forms of obesity. Here, we review the mechanisms by which leptin activates intracellular signals and the roles that these signals play in leptin action in vivo. Furthermore, we discuss potential mechanisms of leptin resistance, specifically focusing on data regarding the neuroanatomical locus of leptin resistance and potential mechanisms by which expression of the suppressor of cytokine signaling-3 may impair leptin action.

Right-to-left shunt assessed by contrast transcranial Doppler sonography: new insights

OBJECTIVE

Simple diagnostic techniques such as contrast transcranial Doppler sonography (cTCDS) are popular for assessing a right-to-left shunt (RLS) because of their high sensitivity. In this study, we applied cTCDS to a large patient group with a patent foramen ovale, proved by contrast transesophageal echocardiography (TEE).

METHODS

One hundred one patients with stroke, in whom a patent RLS had been shown on contrast TEE, were investigated by TCDS of both middle cerebral arteries. Injection of 10 mL of agitated saline was applied without and subsequently with the Valsalva maneuver (VM) at the beginning of the contrast agent injection, and then 10 mL of a galactose-based contrast agent was applied in the same protocol.

RESULTS

In all patients, cTCDS with the galactose contrast agent showed an RLS when performed with VM, but it showed an RLS in only 59 patients without VM. In contrast, saline showed an RLS in 54 patients with VM and in 20 patients without VM. The differences in diagnostic sensitivity were statistically significant (P < .001). Eighteen patients had only 1 microembolic signal (MES) after galactose injection, whereas others had more. The mean (SD) arrival times of the MES were 9 (6) seconds (range, 1-51 seconds) after galactose injection with VM and 9 (3) seconds (range, 2-20 seconds) after agitated saline with VM. The differences were not significant.

CONCLUSIONS

Contrast TCDS with VM shows a TEE-proven RLS with 100% sensitivity, but this was not true with galactose application without VM or agitated saline with or without VM. Therefore, use of the galactose contrast agent with VM is strongly recommended for detecting an RLS on TCDS. However, the arrival time and number of MESs detected need to be tested further.

[Prevalence of patent foramen ovale in young patients with cerebral ischemic accident of unknown origin]

INTRODUCTION AND OBJECTIVE

Patent foramen ovale has been associated with stroke in young patients with cryptogenic stroke. The purpose of this study is to examine the prevalence of patent foramen ovale in this group of patients, as well as their anatomical and functional characteristics by contrast echocardiography, trying to determine ictus risk markers in young patients with acute ischemic stroke.

PATIENTS AND METHOD

Prospective study of 90 patients under the age of 50 who were hospitalised consecutively due to a clinical presentation suggestive of stroke. No cause was found in 55 out of 90 (group I) and the rest, in which an stroke was finally disregarded, were used as the control group (group II). A transthoracic and transesophageal echocardiography examination with 2 types of contrast agents was performed in all patients to determine the presence of a patent foramen ovale and its anatomical and functional characteristics.

RESULTS

Patent foramen ovale was observed more frequently in group I than in group II (43 versus 21%; p < 0.05). Among patients with a patent foramen ovale those with an ischemic stroke showed greater mobility of the oval membrane, more frequent large shunts of contrast in a single frame in the left heart, and more frequent shunts at rest. Transesophageal echocardiography without contrast showed a high sensitivity (90%) and specificity (93%) for detecting anatomically permeable foramen ovale whereas contrast transthoracic echocardiography showed a low sensitivity (13%). There were no differences between the two contrasts used.

CONCLUSIONS

Near half of young patients with ischemic stroke of an unknown origin have a patent foramen ovale. A bigger mobility of the membrane of the oval cavity and a large degree of shunt contrast as well as shunt at rest detected by contrast transesophageal echocardiography, seem to identify patent foramen ovale patients with ischemic stroke. In these patients, transthoracic echocardiography has low sensibility for detecting permeability of the foramen ovale.

Inherited thrombophilic disorders in young adults with ischemic stroke and patent foramen ovale

BACKGROUND AND PURPOSE

The pathogenic link between patent foramen ovale (PFO) and stroke remains unknown in most cases. We investigated the association between inherited thrombophilic disorders and PFO-related strokes in a series of young adults in the setting of a case-control study.

METHODS

We investigated 125 consecutive subjects (age, 34.7+/-7.3 years) with ischemic stroke and 149 age- and sex-matched control subjects. PFO was assessed in all patients with transcranial Doppler sonography with intravenous injection of agitated saline according to a standardized protocol. Genetic analyses for the factor V (FV)(G1691A) mutation, the prothrombin (PT)(G20210A) variant, and the TT677 genotype of methylenetetrahydrofolate reductase (MTHFR) were performed in all subjects.

RESULTS

A pathogenic role of PFO was presumed in 36 patients (PFO+). Interatrial right-to-left shunt either was not detected or was considered unrelated to stroke occurrence in the remaining 89 patients (PFO-). The PT(G20210A) variant was more frequent in the PFO+ group compared with control subjects and the PFO- group (PFO+ versus control subjects, 11% versus 2%; 95% CI, 0.04 to 0.94; PFO+ versus PFO-, 11% versus 1.1%; 95% CI, 1.09 to 109; P=0.047). A similar distribution was observed for subjects carrying either the PT(G20210A) variant or the FV(G1691A) mutation (PFO+ versus control subjects, 19.4% versus 5.3%; 95% CI, 0.08 to 0.75; PFO+ versus PFO-, 19.4% versus 3.3%; 95% CI, 1.45 to 26.1; P=0.021). Combined thrombophilic defects were observed in 3 subjects of the PFO+ group, in 2 control subjects (8.3% versus 1.3%; 95% CI, 0.01 to 0.66; P=0.015), and in 0 subjects in the PFO- group. A trend toward a difference in the frequency of the FV(G1691A) mutation between PFO+ and control subjects was found after bivariate analysis (11% versus 3.3%; P=0.068) but not after multinomial logistic regression analysis. No significant association was found in the distribution of the TT MTHFR genotype in the 3 groups.

CONCLUSIONS

In young adults, the PT(G20210A) variant and, to a lesser extent, the FV(G1691A) mutation may represent risk factors for PFO-related cerebral infarcts. A role of systemic thrombophilic disorders in the pathogenesis of this specific subtype of stroke may be hypothesized.