Diagnosis of secondary source of right-to-left shunt with balloon occlusion of patent foramen ovale and power M-mode transcranial Doppler.

OBJECTIVES: We sought to assess the prevalence of secondary right-to-left circulatory shunt (RLS) in patients undergoing transcatheter closure of patent foramen ovale (PFO) as detected by power M-mode transcranial Doppler (TCD) and intracardiac echocardiography. BACKGROUND: Prevalence of residual RLS in late follow-up after PFO closure may be as high as 34%. Other cardiac and noncardiac sources of RLS may coexist and obscure PFO closure evaluation. METHODS: Eighty-eight patients who underwent transcatheter PFO closure to prevent recurrent paradoxical cerebral embolism between June 2005 and December 2006 were evaluated for a secondary source of RLS. Before device deployment, a sizing balloon was inflated in the PFO tunnel and agitated saline contrast was injected into the inferior vena cava. Clinically significant secondary RLS was defined as >10 embolic tracks on TCD at rest or immediately after calibrated (40 mm Hg), sustained (10 s) respiratory strain, with corresponding negative color-flow Doppler. Late residual RLS was evaluated in all patients with TCD and transthoracic echocardiography (mean: 192 days; 95% confidence interval [CI]: 161 to 223 days). RESULTS: The sample (n = 84) was 59% female, age 49 +/- 14 years. Seventeen patients (20%; 95% CI: 11.7 to 28.8) had secondary RLS during balloon occlusion. At late follow-up (n = 66), 13 of 14 (93%) patients with secondary RLS and 23 of 52 (44%) patients without secondary RLS had residual RLS (p = 0.002). CONCLUSIONS: This is the first report to systematically assess the prevalence of secondary RLS in patients undergoing PFO closure. Residual RLS detected by TCD may be due to secondary RLS, which may have implications for clinical outcomes.

Unilateral versus bilateral middle cerebral artery detection of right-to-left shunt by power M-mode transcranial doppler.

BACKGROUND AND PURPOSE: Comparison was performed between unilateral and bilateral power M-mode transcranial Doppler to detect right-to-left circulatory shunt (RLS). METHODS: Recorded Doppler data from 87 patients with confirmed RLS referred for transcatheter closure of patent foramen ovale were reanalyzed for embolic tracks (ET) counted from left and right temporal bone windows during bubble study. Unilateral counts were obtained by multiplying each side by 2; bilateral counts were obtained by summing left and right ET. Both unilateral and bilateral ET were converted to a 6-point logarithmic grade. Sex and age group subanalyses were performed. RESULTS: At rest, significantly more ET were detected with bilateral versus unilateral detection (P= .01), but not following Valsalva (P= .13). Unilateral and bilateral detection were equally able to detect large RLS (grades IV or V) following Valsalva (P= 1.00). For the group aged > or =55 years, the right-hand side yielded greater ET than the left-hand side (mean difference 9%+/- 37; 95% confidence interval -3 to 21%) at rest (P= .01), but not following Valsalva (mean difference 1%+/- 25; 95% confidence interval -7 to 9%, P= .10). CONCLUSIONS: Unilateral detection of ET by power M-mode transcranial Doppler is equivalent to bilateral detection to assess RLS.

Frequency of migraine headache relief following patent foramen ovale "closure" despite residual right-to-left shunt.

Retrospective studies have shown improvement in migraines after patent foramen ovale (PFO) closure. To date, no study has evaluated whether the completeness of closure affects headache status; therefore, the objective of this study was to evaluate the impact of residual right-to-left shunt (RLS) on migraine symptoms after transcatheter PFO closure in migraineurs with and without aura. This was a small-series, single-center, retrospective analysis of late follow-up data on 77 patients with presumed paradoxical embolism and migraine who underwent PFO closure for secondary stroke prevention. Power M-mode transcranial Doppler was used to assess RLS at baseline and 6 and 12 months after closure. A standardized migraine questionnaire was administered at baseline and 6, 12, and 24 months after closure. Fifty-five (71%) patients had migraine with aura. Final closure and migraine status were available for 67 patients; 23 (34%) had incomplete PFO closure, defined as 30 embolic tracks detected at final power M-mode transcranial Doppler examination (median 366 days, 95% confidence interval 332 to 474). Migraine relief (> or = 50% reduction in frequency) was independent of closure status (77% complete closure vs 83% incomplete closure, p = 0.76) at late follow-up (540 days, 95% confidence interval 537 to 711). Migraineurs with aura were 4.5 times more likely to experience migraine relief than migraineurs without aura. In conclusion, migraine relief may occur despite residual RLS after transcatheter PFO closure, which may suggest a reduction in RLS burden below a neuronal threshold that triggers migraine; however, this warrants further investigation. Migraine with aura may be an independent predictor of relief after PFO closure.

Migraineurs with patent foramen ovale have larger right-to-left shunt despite similar atrial septal characteristics.

The objective of the study was to assess differences in proportion of large right-to-left shunt (RLS) and atrial septal characteristics between migraineurs and non-migraineurs referred for transcatheter closure of patent foramen ovale (PF0). This retrospective study took place in a large metropolitan medical centre. The patients were migraineurs with aura (n=52), migraineurs without aura (n=19) and non-migraineurs (n=149). RLS was evaluated before closure using bilateral power m-mode transcranial Doppler at rest and after calibrated, sustained Valsalva manoeuvre, and graded with a validated 0-5 scale. Intracardiac echocardiography was used to assess atrial septal characteristics. Migraineurs had a higher proportion of large RLS (Grade IV or V) than nonmigraineurs at rest and after calibrated Valsalva (rest, p=0.04; Valsalva, p=0.01). Atrial septal characteristics were similar between groups. Migraine is associated with larger RLS at rest and strain; however migraine status does not predict PFO characteristics.

Outcomes after transcatheter closure of patent foramen ovale in patients with paradoxical embolism.

The purpose of the present study was to assess clinical outcomes and closure status after the transcatheter closure of patent foramen ovale. Two hundred thirty-seven consecutive patients (mean age 53 +/- 15 years; 48% men) who underwent patent foramen ovale closure for the prevention of recurrent stroke were evaluated. Primary end points were death, recurrent stroke, and residual right-to-left shunt (RLS). Closure status was monitored at 1, 6, 12, 24, 36, and 48 months after the index procedure by power M-mode transcranial Doppler and was defined by the number of embolic tracks detected after the release of a sustained, calibrated Valsalva maneuver. During a mean follow-up period of 568 +/- 364 days, the cumulative event rate for recurrent stroke (n = 8) was 3.4%, for an estimated event-free survival of 0.94 (SE 0.03). There was a significant difference in the estimated probability of recurrent stroke for patients grouped by age (< or =55 years 1.4% vs >55 years 6.6%, p = 0.03). There were 7 deaths (3.0%), 1 secondary to and 6 unrelated to recurrent strokes, and 3 surgical explantations (1.3%). Event-free survival, defined as freedom from death, stroke, or explantation, was 0.92 (SE 0.02). The magnitude of RLS was significantly less at late follow-up compared with baseline (grade 4.6 +/- 0.7 vs 1.8 +/- 1.6, p <0.001). Complete closure or minimal residual RLS (grade 0 to II) was achieved in 66% of patients. Device type (CardioSEAL or Amplatzer) did not affect the risk for adverse events or the presence of large residual RLS. In conclusion, transcatheter patent foramen ovale closure is associated with a low recurrent stroke rate in long-term follow-up.

Power M-Mode Doppler and single-gate spectral analysis using a 2-MHz pulsed-wave Doppler transducer to directly detect cervical internal carotid artery stenosis: use of the continuity principle: report of a novel technique.

BACKGROUND AND PURPOSE: We hypothesized that direct cervical investigation with Power M-Mode Doppler (PMD) combined with single-gate Doppler spectral analysis (SGDSA) using a 2-MHz pulsed-wave Doppler transducer would show reasonable accuracy parameters when compared with standard color-coded carotid duplex ultrasound (CDU). METHODS: We prospectively screened for cervical internal carotid artery (ICA) stenosis by direct observation using a 2 MHz PMD/SGDSA device. PMD identified the artery (location, depth, flow direction) and SGDSA assessed waveform; peak systolic, end diastolic, and mean flow velocities (MFV) of the common carotid artery; cervical ICA proximally and distally; and external carotid artery. Diagnostic accuracy was compared with concurrent carotid duplex ultrasound. The continuity principle was applied using the proximal/distal cervical ICA MFV ratio. RESULTS: We examined 456 vessels (228 patients). Using ICA proximally/ICA distally MFV ratio of 1.5 or greater or absence of ICA signature, for 40% to 59% or greater stenosis (including occlusions), sensitivity was 75.4%, specificity 99.8%, positive predictive value 97.7%, negative predictive value 96.6%, and accuracy 96.7%. For MFV ratio 1.6 or greater or absence of ICA signature and 60% to 79% or greater stenosis (including occlusions), sensitivity was 92.3%, specificity 98.1%, positive predictive value 81.8%, negative predictive value 99.3%, and accuracy 97.6%. CONCLUSIONS: Use of combined PMD and SGDSA to directly observe the extracranial ICA is reasonably accurate compared with carotid duplex ultrasound. Using the MFV ratio of proximal/distal extracranial ICA improves accuracy parameters and provides a quick and effective bedside screen for ICA stenosis. This novel technique should be considered part of the standard PMD/transcranial Doppler examination.

Migraine headache relief after transcatheter closure of patent foramen ovale.

OBJECTIVES: The purpose of this study was to determine the effects of transcatheter patent foramen ovale (PFO) closure on migraine frequency in patients with paradoxical cerebral embolism. BACKGROUND: The prevalence of migraine headache is higher in cryptogenic stroke patients with PFO than in the general population. Previous studies have suggested that closure of the PFO may reduce migrainous symptoms. METHODS: Between April 2001 and December 2003, 162 consecutive patients with paradoxical cerebral embolism underwent transcatheter PFO closure for prevention of recurrent cryptogenic stroke or transient ischemic attack. A one-year retrospective analysis of migraine symptoms before and after PFO closure was performed. RESULTS: Active migraine was present in 35% (57 of 162) of patients, and 68% (39 of 57) experienced migrainous aura; 50 patients were available for analysis at one year. Complete resolution of migraine symptoms occurred in 56% (28 of 50) of patients, and 14% (7 of 50) of patients reported a significant (>or=50%) reduction in migraine frequency. Patients reported an 80% reduction in the mean number of migraine episodes per month after PFO closure (6.8 +/- 9.6 before closure vs. 1.4 +/- 3.4 after closure, p < 0.001). Results were independent of completeness of PFO closure at one year. CONCLUSIONS: In patients with paradoxical cerebral embolism, migraine headaches are more frequent than in the general population, and transcatheter closure of the PFO results in complete resolution or marked reduction in frequency of migraine headache.

Power m-mode transcranial Doppler for diagnosis of patent foramen ovale and assessing transcatheter closure.

BACKGROUND AND PURPOSE: Transcatheter closure of patent foramen ovale (PFO) can benefit from a less invasive diagnostic method than transesophageal echocardiography (TEE). Thirty-three gate power m-mode transcranial Doppler (pmTCD) was evaluated for its accuracy in diagnosis of PFO and utility in evaluating residual intracardiac right-to-left shunt (RLS) following transcatheter closure. METHODS: The sensitivity of pmTCD and single-gate TCD (sgTCD) to detect contrast bubble emboli through RLS was compared during transcatheter PFO closure. During 100 preclosure diagnostic evaluations and in 81 postclosure assessments, embolic tracks on pmTCD were counted following intravenous contrast injections and were graded using a 6-level logarithmic scale. The accuracy of TEE and pmTCD was separately compared to PFO anatomical findings during transcatheter closures. RESULTS: There were significantly more microemboli detectable on pmTCD (322 +/- 166; 95% confidence interval [CI], 388-257) than on sgTCD (186 +/- 109; 95% CI, 229-143; P < .001). McNemar change tests suggest that the diagnostic capabilities of pmTCD and TEE for detecting PFO are comparable and correspond to the anatomical findings determined during cardiac catheterization (P = .69 and .45, respectively). During 6-month postclosure evaluation (mean = 185 days), 66% of the patients demonstrated successful closure without significant RLS (ie, grades 0, I, or II), and 34% were found to have incomplete closure with significant RLS (ie, grades III, IV, or V). CONCLUSIONS: pmTCD provides greater sensitivity to contrast bubble emboli than does sgTCD. Among candidates for transcatheter closure, pmTCD provides an improved noninvasive method for diagnosing PFO and evaluating transcatheter closure.

Power M-mode Doppler (PMD) for observing cerebral blood flow and tracking emboli.

Difficulties in location of transcranial ultrasound (US) windows and blood flow in cerebral vessels, and unambiguous detection of microemboli, have limited expansion of transcranial Doppler US. We developed a new transcranial Doppler modality, power M-mode Doppler (PMD), for addressing these issues. A 2-MHz digital Doppler (Spencer Technologies TCD100M) having 33 sample gates placed with 2-mm spacing was configured to display Doppler signal power, colored red and blue for directionality, in an M-mode format. The spectrogram from a user-selected depth was displayed simultaneously. This system was then explored on healthy subjects and patients presenting with varying cerebrovascular pathology. PMD facilitated window location and alignment of the US beam to view blood flow from multiple vessels simultaneously, without sound or spectral clues. Microemboli appeared as characteristic sloping high-power tracks in the PMD image. Power M-mode Doppler is a new paradigm facilitating vessel location, diagnosis, monitoring and microembolus detection.

Detection of Embolism with Doppler Ultrasound: A Review.

Doppler detection of venous and arterial gas emboli has been recognized since 1968. The technology has been applied using 5-MHz ultrasound to study decompression sickness and monitor cardiopulmonary bypass and intracranial surgery. Since the advent of transcranial Doppler, which requires the use of lower ultrasonic carrier frequencies to penetrate the temporal bone, the detection of particulates moving in the bloodstream has been available. Using 2 MHz, microembolic signals have been detected in a variety of clinical situations, including cardiac conditions known to have high probabilities to produce embolic stroke. The basic features of a Doppler embolic signal have been clarified, and many investigators are applying the technology to determine the clinical significance of the detected emboli and their use in diagnosis and medical and surgical treatments. The basis for automatic sizing, counting, and characterizing the emboli is under development. The applications of Doppler detection of emboli will range from diagnosis and localization of embolic sources to improvement in surgical techniques and adjustments in medical treatments. (ECHOCARDIOGRAPHY, Volume 13, September 1996)

Doppler Microembolic Signals for Diagnosis of Ulcerated Carotid Artery Plaques.

BACKGROUND: Finding the pathological meaning of Doppler microembolic signals is important to developing the clinical applications of this new technology. METHODS: Two hundred eighty-four plaques, removed at carotid endarterectomy, were examined by the surgeon and pathologist for evidence of ulceration. The ipsilateral middle cerebral artery was monitored, with 2-MHz pulsed Doppler, preoperatively and during surgical mobilization of the carotid arteries. Associated Doppler embolic signals representing formed element emboli (FEE) were sought for 15-273 (mean 60) minutes. The embolization rate was calculated in FEE/hour. RESULTS: Preoperatively, 21% of patients demonstrated FEEs. During surgical mobilization of the carotid arteries, 51% demonstrated FEEs. A 79% prevalence of plaque ulceration was found. Analysis demonstrated 61% sensitivity and specificity, and an 86% positive predictive value. The positive predictive value increased progressively with higher FEE rates, up to 100% for patients with >60 FEE/hour. CONCLUSIONS: FEEs detected in the middle cerebral artery ipsilateral to carotid artery stenosis are diagnostic of plaque ulceration or luminal thrombus formation. Other embolic sources may be ruled out by monitoring the contralateral carotid artery system and the ipsilateral carotid arteries. There is no significant relationship between the number and prevalence of FEEs and the severity of stenosis or preoperative symptoms. Postoperative cerebral complications of stroke were associated with more FEEs than were postoperative transient ischemic attacks. (ECHOCARDIOGRAPHY, Volume 13, September 1996)