scholarly journals Assessments of flow by transcranial Doppler ultrasound in the middle cerebral artery during exercise in humans

1999 ◽  
Vol 86 (5) ◽  
pp. 1632-1637 ◽  
Author(s):  
Marc J. Poulin ◽  
Rebecca J. Syed ◽  
Peter A. Robbins
Keyword(s):  
Doppler Ultrasound ◽  
Transcranial Doppler ◽  
Transcranial Doppler Ultrasound ◽  
Weighted Mean ◽  
Arterial Pressure Waveform ◽  
Mean Velocity ◽  
Nonsignificant Increase ◽  
Human Volunteers ◽  
Graded Exercise ◽  
Exercise In Humans

This study examined the consistency between three indexes of cerebral blood flow (CBF) obtained by using transcranial Doppler ultrasound in eight human volunteers. Each subject undertook three sessions of graded exercise, consisting of 6 min of rest, 6 min at 20% of maximal oxygen uptake (V˙o 2 max), 6 min at 40% V˙o 2 max, and 6 min of recovery. Values were obtained every 10 ms for the velocity associated with the maximal frequency of the Doppler shift ( V P), the intensity-weighted mean velocity ( V IWM), and total signal power ( P). Beat-by-beat averages for three indexes ([Formula: see text] P,[Formula: see text] IWM,[Formula: see text]provided significantly different results for the percent changes in CBF with exercise. At 20% ofV˙o 2 max,[Formula: see text] P and[Formula: see text] IWM showed significant ( P < 0.05) increases of 8 and 6%, respectively, whereas[Formula: see text]showed a nonsignificant increase of 3%. At 40% ofV˙o 2 max,[Formula: see text] P and[Formula: see text] IWM showed significant ( P < 0.05) increases of 14 and 8%, respectively, whereas[Formula: see text]showed a nonsignificant increase of 4%. Our results suggest that the increase in CBF with exercise that has been reported with transcranial Doppler ultrasound needs to be treated with caution, as much of the response could arise as an artifact from the increase in amplitude and frequency of the arterial pressure waveform.

Dynamic response of cerebral perfusion during low-intensity cycling exercise: A study using transcranial Doppler ultrasound

2016 ◽  
Vol 2 (11) ◽  
Author(s):  
Mikio Hiura ◽  
Akitaka Muta ◽  
Tadashi Nariai
Keyword(s):  
Doppler Ultrasound ◽  
Transcranial Doppler ◽  
Cerebral Perfusion ◽  
Transcranial Doppler Ultrasound ◽  
Cycle Ergometer ◽  
Moderate Intensity ◽  
Mean Velocity ◽  
Low Intensity ◽  
End Tidal ◽  
Low Intensity Exercise

<p><tt>We investigated the changes in cerebral perfusion during constant low-intensity exercise and the effect of a late increase in workload. Eleven healthy males participated in this study. Four subjects performed 15 min of constant low-intensity exercise on a cycle ergometer, while seven subjects performed 20 min of exercise consisting of 17 min of low-intensity exercise, which was incremented to moderate-intensity for the final 3 min. As an index for cerebral perfusion, the time-averaged mean velocity of flow in the middle cerebral artery (MCAV<sub>mean</sub>) was measured using transcranial Doppler ultrasound. During the 15-min of low-intensity exercise (78 ± 3 Watts), pulmonary oxygen consumption (<em>V</em>O<sub>2</sub>) increased to 19.1 ± 2.5 ml/min/kg within 3-6 min, while </tt>end-tidal pressure of carbon dioxide (P<sub>ET</sub>CO<sub>2</sub>) increased to <tt>42.0 ± 3.2 mmHg, and MCAV<sub>mean</sub> increased to a peak 19.2 ± 9.1 % above the pre-exercise resting level then gradually decreased back toward the resting level. During the 20-min exercise at low and then moderate intensity </tt>(77 <tt>± 4 and </tt>111 <tt>± 7 Watts for low and moderate intensity, respectively), <em>V</em>O<sub>2</sub> increased from 19.1 ± 2.8 to 24.2 ± 3.6 ml/min/kg after the late increment in exercise intensity, while</tt> P<sub>ET</sub>CO<sub>2</sub> remained unchanged (<tt>p = 0.48, Tukey’s post hoc test</tt>), and <tt>MCAV<sub>mean</sub> tended to increase but did not change significantly. K</tt>inetic analysis of <em>V</em>O<sub>2</sub> and <tt>MCAV<sub>mean</sub></tt> at low and moderate exercise intensities <tt>using a monoexponential model revealed that the </tt>time constant (τ) for <em>V</em>O<sub>2</sub> was significantly related to the τ for <tt>MCAV<sub>mean</sub></tt> at low (n=9) (R<sup>2 </sup>=0.52, P =0.03) and moderate intensity (n=6) (R<sup>2</sup> = 0.69, P =0.04). These findings imply that cardiac output exerts an indirect effect to alter cerebral perfusion and that cerebral autoregulation likely operates to stabilize cerebral blood flow during prolonged exercise at a constant workload.</p>

scholarly journals Transcranial Doppler Waveforms During Intra-aortic Balloon Pump Counterpulsation for Vasospasm Detection After Subarachnoid Hemorrhage

Neurosurgery ◽  
2017 ◽  
Vol 83 (3) ◽  
pp. 416-421 ◽  
Author(s):  
Nicholas A Morris ◽  
Nathan Manning ◽  
Randolph S Marshall ◽  
E Sander Connolly ◽  
Jan Claassen ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Flow Velocity ◽  
Doppler Ultrasound ◽  
Transcranial Doppler ◽  
Cerebral Perfusion ◽  
Delayed Cerebral Ischemia ◽  
Transcranial Doppler Ultrasound ◽  
Mean Velocity ◽  
Doppler Waveform ◽  
Velocity Coefficient

Abstract BACKGROUND Transcranial Doppler ultrasound is a standard screening tool for vasospasm after subarachnoid hemorrhage. Prevention of vasospasm-induced delayed cerebral ischemia after subarachnoid hemorrhage depends on optimization of cerebral perfusion pressure, which can be challenged by neurogenic stress cardiomyopathy. Intra-aortic balloon pumps have been utilized to augment cerebral perfusion, but they change the transcranial Doppler waveform, altering its interpretability for vasospasm screening. OBJECTIVE To assess the features of the transcranial Doppler waveform that correlate with vasospasm. METHODS We retrospectively reviewed cases of subarachnoid hemorrhage that underwent same-day transcranial Doppler ultrasound and angiography. Transcranial Doppler waveforms were assessed for mean velocity, peak systolic velocity, balloon pump-augmented diastolic velocity, and a novel feature, “delta velocity” (balloon pump-augmented velocity − systolic velocity). Relationship of flow velocity features to vasospasm was estimated by generalized estimating equation models using a Gaussian distribution and an exchangeable correlation structure. RESULTS There were 31 transcranial Doppler and angiography pairings (12 CT angiography/19 digital subtraction angiography) from 4 patients. Fourteen pairings had proximal vasospasm by angiography. Delta velocity was associated with proximal vasospasm (coefficient –6.8 [95% CI –9.8 to –3.8], P &lt; .001). There was no significant correlation with proximal vasospasm for mean velocity (coefficient –13.0 [95% CI –29.3 to 3.4], P = .12), systolic velocity (coefficient –8.7 [95% CI –24.8 to 7.3], P = .29), or balloon pump-augmented velocity (coefficient –15.3 [95% CI –31.3 to 0.71], P = .06). CONCLUSION Delta velocity, a novel transcranial Doppler flow velocity feature, may reflect vasospasm in patients with subarachnoid hemorrhage and intra-aortic balloon pumps.

High-Grade Stenosis of a Traumatic Brachiocephalic Pseudoaneurysm and the Change in Cerebral Blood Flow Assessed With Transcranial Doppler Ultrasound

2021 ◽  
pp. 154431672110023
Author(s):  
Winnie Nguyen ◽  
Tammy Albanese ◽  
Vanessa Tran ◽  
Anne Moore ◽  
Laligam Sekhar
Keyword(s):  
Doppler Ultrasound ◽  
Transcranial Doppler ◽  
Transcranial Doppler Ultrasound ◽  
Computed Tomographic Angiography ◽  
Computed Tomographic ◽  
Vertebral Arteries ◽  
Luminal Narrowing ◽  
Basilar Arteries ◽  
The Right ◽  
Tomographic Angiography

This is a case report of a 35-year-old female pedestrian struck by a semi-truck. computed tomographic angiography (CTA) revealed a pseudoaneurysm at the proximal brachiocephalic artery measuring 1.8 cm in cranio-caudal length and 1.2 × 0.6 cm transverse. Just distal to the pseudoaneurysm, there was severe luminal narrowing caused by either a dissection flap or mural thrombus. Due to profound left-sided weakness, transcranial Doppler ultrasound was performed which demonstrated “hesitant” waveforms in the right middle cerebral and right vertebral arteries secondary to proximal obstruction. Hesitant waveforms display mid-systolic velocity deceleration and may also be referred to as the “bunny” waveform. Emboli monitoring of the right middle cerebral and basilar arteries were positive for active embolization

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