Patency of the foramen ovale is associated with migraine with aura but not with migraine without aura. The increased risk of stroke found in epidemiologic studies in patients with migraine with aura may be explained by an increased propensity to paradoxical cerebral embolism.

A relationship between migraine and patent foramen ovale (PFO) has been observed in relatively small series of patients so far. Furthermore, the exact mechanism underlying such an association remains unknown. In the present study we determined the prevalence of PFO by contrast–enhanced transcranial Doppler (TCD) in a group of 260 patients with migraine with aura (MA+), 74 patients with migraine without aura (MA–), and 38 patients with cluster headache (CH). One–hundred–sixty–one MA+subjects (61.9%), 12 MA–subjects (16.2%), and 14 CH–subjects (36.8%) were PFO–carriers. The association was independent on the frequency of migraine attacks and complexity of aura. Finally, among the 15 patients who had a history of at least one migraine attack occurring during a Valsalva maneuver only one subject turned out to be PFO–carrier. Our findings confirm previous observations of a link between MA+, CH, and PFO. They also suggest that such an association is independent on migraine clinical phenotype and is probably unrelated to the pathogenic mechanism of paradoxical embolism.

Transcranial Doppler sonography (TCD) can detect the passage through the middle cerebral artery of microbubbles present in intravenous injected saline when an intracardiac right-to-left shunt occurs. Given the increasingly recognized importance of patent foramen ovale (PFO) as a possible anatomical factor predisposing to stroke, we tried to assess the efficiency of TCD in the evaluation of PFO in comparison to the gold standard represented by transesophageal echocardiography (TEE). Seventy-two consecutive patients scheduled for TEE also underwent TCD, simultaneously in 18 cases. A 20-ml agitated saline bolus was injected into an antecubital vein through an indwelling catheter while the patient was performing a Valsalva manoeuvre. The procedure was repeated a maximum of 10 times or until the contrast medium was tracked from the right to left atrium (TEE+) and/or the high-intensity spike typical for embolism was recorded on TCD (TCD+). Among non-simultaneous cases, the first 14 were studied with a non-standardized protocol: the resulting sensitivity and specificity of TCD as compared to TEE were both 43% (TEE+/TCD+ = 3; TEE–/TCD– = 3; TCD+/TEE– = 4; TCD–/TEE+ = 4). In all the 18 simultaneous examinations, however, there was 100% agreement between TEE and TCD (TEE+/TCD+ = 12; TEE–/TCD– = 6). Moreover, when the protocol was standardized in 40 further patients studied non-simultaneously, sensitivity and specificity were 90 and 100%, respectively (TCD+/TEE+ = 19; TCD–/ TEE– = 19; TCD–/TEE+ = 2; TCD+/TEE– = 0) Standardization was obtained by timing of Valsalva manoeuvre to injection, delay of embolic signals, caliber of venous catheters, content of air bubbles in the saline, velocity of injection. In conclusion, when properly standardized techniques are applied, TCD can be used as a screening test for the detection of PFO.

Injection compression molding is an injection molding process with the addition of a compression stage after the injection. This process is useful for the injection molding of precision parts. A stable and controlled manufacturing process is needed to guarantee reliability of complex products, and usually process optimization is achieved by experimental and time consuming approaches. However, for being competitive a minimal market time is a very important requirement and computer simulations can help to optimize the process at the only expense of computational time. This paper reports and discusses for the first time the results of a 3D finite element simulation of reactive injection compression molding (RICM) by commercial software for the production of rubber diaphragms. In particular, the stages of mold filling dynamics and material curing are analyzed and the results verified with experimental tests. To get an accurate representation of the process, the rheological behavior, thermal properties, and kinetic behavior during curing of the real rubber compound were described by mathematical models. A differential scanning calorimeter (DSC) and a capillary rheometer are employed to characterize the rubber material in order to achieve an appropriate curing reaction and viscosity models, respectively. The computations are found to be in good agreement with the experimental results, indicating that reliable information on material viscosity and curing kinetics can play a key role in making well-founded predictions and avoiding trial and error methods.

Transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) permits the detection of high intensity transient signals (HITS), which are believed to represent microemboli. Non-valvular atrial fibrillation (NVAF) and prosthetic heart valves (PV) are important risk factors for embolic stroke. We evaluated both the prevalence and the frequency of microemboli in these high risk groups and the correlation with previous stroke. Sixty-six patients were monitored for 30 min on both MCAs sequentially. Twenty healthy subjects were studied as well. The total number of HITS recorded on both sides, expressed as HITS/h, was used for comparison. In NVAF patients (n = 24) the prevalence of HITS was 25%, in PV (n = 16) 62% and in those patients in whom PV coexisted with atrial fibrillation (PVAF) (n = 26), it was 42%. None in the control group showed HITS. HITS occurred significantly more frequently in PVAF (12.3/h) than in both NVAF (1.4/h, p = 0.007) and PV (2.7/h, p = 0.011), whereas there was no difference between PV and NVAF. The prevalence of HITS was not statistically different in patients with and without previous stroke, but among HITS positive patients those with previous stroke had a significantly higher HITS frequency (18.9 vs 8.5/h, p = 0.04). In conclusion, in patients with cardiac embolic sources the frequency of HITS increases from the classes with the lower (NVAF, PV) to the class with the highest (PVAF) risk factor. Patients with previous stroke have more HITS than asymptomatic ones. Therefore, embolus detection monitoring seems a promising tool in the assessment of the individual stroke risk in patients with cardiac embolic sources.