Relation Between Interatrial Shunts and Decompression Sickness in Divers

339

233

Background and Purpose-Transesophageal echocardiography (TEE) has detected a high prevalence of patent foramen ovale (PFO) in stroke patients, but the clinical implications of the distinctive characteristics of this patency are still a matter of debate. Methods-We studied 350 patients with acute ischemic stroke or transient ischemic attack (TIA) within 1 week of admission. Of these, 101 (29%) were identified by contrast TEE to have a PFO; 86 patients (25%) were cryptogenic stroke patients, and 163 were excluded because of the presence of a definite or possible arterial or clinical evidence of a source of emboli or small-vessel disease. Thirteen PFO subjects without a history of embolism were designated as the control group. All PFO and cryptogenic stroke patients were followed up by neurological visits. Results-Compared with controls, PFO patients with acute stroke or TIA more frequently presented with a right-to-left shunt at rest and a higher membrane mobility (PϽ0.05). Patients with these characteristics were considered to be at high risk. During a median follow-up period of 31 months (range, 4 to 58 months), 8 PFO and 18 cryptogenic stroke patients experienced recurrent cerebrovascular events. The cumulative estimate of risk of cerebrovascular event recurrence at 3 years was 4.3% (95% confidence interval [CI], 0% to 10.2%) for "low-risk" PFO patients, 12.5% (95% CI, 0% to 26.1%) for "high-risk" PFO patients, and 16.3% (95% CI, 7.2% to 25.4%) for cryptogenic stroke patients (high-risk PFO versus low-risk PFO, Pϭ0.05). Conclusions-The association of right-to-left shunting at rest and high membrane mobility, as detected by contrast TEE, seems to identify PFO patients with cerebrovascular ischemic events who are at higher risk for recurrent brain embolism.

Section: Possible Clinical Implicationsmentioning

confidence: 99%

Morphological and Functional Characteristics of Patent Foramen Ovale and Their Embolic Implications

Castro

Cartoni

Fiorelli

et al. 2000

339

233

“…7,8 Some authors do not confirm the association between isolated PFO and increased risk of ischemic stroke 9 or recurrent stroke. 4,10 The size of PFO and the degree of right-to-left cardiac shunt (RLS) in these disorders are debated.…”

mentioning

confidence: 99%

Controlled Contrast Transcranial Doppler and Arterial Blood Gas Analysis to Quantify Shunt Through Patent Foramen Ovale

Devuyst

Piechowski-Jóźwiak

Karapanayiotides

et al. 2004

Background and Purpose-A right-to-left shunt can be identified by contrast transcranial Doppler ultrasonography (c-TCD) at rest and/or after a Valsalva maneuver (VM) or by arterial blood gas (ABG) measurement. We assessed the influence of controlled strain pressures and durations during VM on the right-to-left passage of microbubbles, on which depends the shunt classification by c-TCD, and correlated it with the right-to-left shunt evaluation by ABG measurements in stroke patients with patent foramen ovale (PFO). Methods-We evaluated 40 stroke patients with transesophageal echocardiography-documented PFO. The microbubbles were recorded with TCD at rest and after 4 different VM conditions with controlled duration and target strain pressures (duration in seconds and pressure in cm H 2 O, respectively): V5-20, V10-20, V5-40, and V10-40. The ABG analysis was performed after pure oxygen breathing in 34 patients, and the shunt was calculated as percentage of cardiac output. Results-Among all VM conditions, V5-40 and V10-40 yielded the greatest median number of microbubbles (84 and 95, respectively; PϽ0.01). A significantly larger number of microbubbles were detected in V5-40 than in V5-20 (PϽ0.001) and in V10-40 than in V10-20 (PϽ0.01). ABG was not sensitive enough to detect a shunt in 31 patients. Conclusions-The increase of VM expiratory pressure magnifies the number of microbubbles irrespective of the strain duration. Because the right-to-left shunt classification in PFO is based on the number of microbubbles, a controlled VM pressure is advised for a reproducible shunt assessment. The ABG measurement is not sensitive enough for shunt assessment in stroke patients with PFO. Key Words: foramen ovale, patent Ⅲ oxygen Ⅲ ultrasonography, Doppler, transcranial Ⅲ Valsalva maneuver T he patent foramen ovale (PFO) with or without coexistent atrial septal aneurysm is generally considered to be associated with brain disorders, including first-ever ischemic stroke in young patients, 1,2 cryptogenic stroke, 3,4 migraine, 4 -6 and cerebral decompression sickness in scuba divers. 7,8 Some authors do not confirm the association between isolated PFO and increased risk of ischemic stroke 9 or recurrent stroke. 4,10 The size of PFO and the degree of right-to-left cardiac shunt (RLS) in these disorders are debated. 4,10 The presence of large PFO and high-degree RLS was demonstrated to increase the risk of cryptogenic stroke, 10 -13 recurrent stroke, 14 -16 the number of silent ischemic brain lesions in divers, 16 migraine with aura, 5,6,18 and cerebral decompression sickness. 19 Other studies show that either percutaneous or surgical closure of PFO decreases the number of recurrent ischemic strokes, 20,21 improves migraine symptoms, 22 and decreases the number of decompression cerebral ischemic events 23 and support the positive relation between highdegree RLS and the aforementioned pathologies.Contrast transcranial Doppler ultrasonography (c-TCD) is a complementary method to contrast-enhanced transesophageal echocardiography (c-T...

“…5,6 Moreover, a high prevalence of RLS has been recently reported in other clinical condition, such as migraine, cluster headache, obstructive apnea, and diving, but the clinical relevance of RLS in these conditions is not yet clear. [7][8][9][10][11][12][13] Gaseous-contrast transcranial Doppler (cTCD) is a highly sensitive and specific technique for the diagnosis of RLS due to patent foramen ovale. 14 -18 Recent evidence has been accumulated on the importance of the dimension of the shunt, evaluated by cTCD, in the stratification for risk of stroke, and a semiquantitative classification with 4 categories has been suggested.…”

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confidence: 99%

Diagnosis of Right-to-Left Shunt With Transcranial Doppler and Vertebrobasilar Recording

Sette

Dinia

Rizzi

et al. 2007

Background and Purpose-Right-to-left shunt (RLS) due to patent foramen ovale is a well-established risk factor for cryptogenic stroke and is highly prevalent in cases of migraine, cluster headache, and obstructive apnea. It can be diagnosed by gaseous-contrast transcranial Doppler, yet in a small percentage of cases it cannot be done owing to an insufficient temporal window. The aim of the study was to compare transtemporal with transoccipital approaches for gaseous-contrast transcranial Doppler for RLS diagnosis. Methods-We evaluated 183 subjects with a standard protocol for RLS diagnosis by simultaneously monitoring the right middle cerebral and vertebrobasilar circulations. Results-Vertebrobasilar recording reached high specificity (100%) and good sensitivity (83.72%) for the diagnosis of RLS after the Valsalva maneuver. For only medium and large shunts, both sensitivity and specificity reached 100%. Time to bubble appearance after injection was higher in the vertebrobasilar circulation (4.36Ϯ1.7 vs 6.77Ϯ2.5 seconds; PϽ0.001). There was a positive correlation between the number of bubbles in the right middle cerebral and vertebrobasilar circulation (ϭ0.97). Conclusions-Transcranial Doppler with vertebrobasilar monitoring is highly sensitive and specific in detecting RLS, particularly when medium or large. It can be proposed for subjects with an insufficient temporal bone window. (Stroke.