Internal Carotid Artery Flow Velocity Research Articles

Is there a relationship between vascular flow parameters of carotid arterial system and trigeminal neuralgia?

Aim: To investigate the flow velocity values and resistance parameters determined by carotid artery doppler ultrasonography (DUS) examination in patients with trigeminal neuralgia (TN). Materials and Methods: 79 patients diagnosed with TN and who underwent carotid DUS were included in the study. Spectral examination results were recorded for the TN side and the healthy side. Results: Peak systolic velocity (PSV) internal carotid artery (ICA), resistive index (RI) (ICA) and PSV (ICA)/PSV external carotid (ECA) values in patients were relatively higher in arterial structures on the TN clinical side compared to the healthy side. RI (ICA)/RI common carotid artery (CCA) value was also high in arterial structures on the TN diagnosed side. Conclusion: It was shown that especially ICA flow velocity and vascular resistance parameters increased in the carotid arterial system on the TN side. These findings indicate that flow parameters in the carotid artery system may also be effective in TN pathophysiology.

Transcranial Doppler in Childhood Moyamoya: An Underutilized Tool?

BackgroundChildren with moyamoya are at high risk for incident and recurrent stroke. Transcranial Doppler (TCD) ultrasound is an attractive option to screen high-risk populations for moyamoya and to provide stroke risk stratification information due to its safety and cost-effectiveness. We used TCD to evaluate cerebral blood flow velocities in children with presurgical moyamoya and to determine if velocities differ between children with stable and unstable disease. MethodsFourteen participants aged ≤21 years with a radiographic diagnosis of moyamoya or moyamoya-like arteriopathy underwent a research TCD at a median age of 7.2 years. TCDs were performed outside of the setting of acute stroke and before surgical revascularization. Arteriopathy was classified as unstable if the participant had a stroke or transient ischemic attack within three months preceding the TCD. ResultsMiddle cerebral artery and internal carotid artery (ICA) blood flow velocities were elevated. The median M1 velocity was 138 cm/s (interquartile range [IQR] 106 to 168). Individual M1 flow velocities were a median of 5.0 S.D.s above age-based normative values. The median distal ICA velocity was 146 cm/s (IQR 124 to 163). Individual ICA flow velocities were a median of 5.9 S.D.s above normative values. Participants with unstable arteriopathy had higher M1 velocities compared with those with stable arteriopathy (170 vs 119 cm/s, P = 0.0003). We did not identify velocity differences based on comorbid conditions or age. ConclusionsThese preliminary data suggest that TCD is a promising tool for screening for cerebral arteriopathies in high-risk pediatric populations and assessment for unstable disease.

Common Carotid Flow Velocity is Associated with Cognition in Older Adults

To assess the relationship between carotid flow velocity and cognitive impairment in patients with mild-moderate (<50%) carotid artery disease. We studied 407 participants with available carotid ultrasound and cognitive measures. We related peak systolic velocity (PSV) and end diastolic velocity (EDV) of internal carotid artery (ICA) and common carotid artery (CCA) and intimal medial thickness (IMT) to Mini Mental State Examination (MMSE), Clock Draw Test (CDT), Activities of Daily Living Scale (ADL)and Montreal Cognitive Assessment (MoCA). EDV of CCA was significantly different in higher and lower MoCA (MMSE) groups. Multiple regression analysis demonstrated that lower EDV was significantly associated with lower MoCA (+0.459 per standard deviation (SD), p<0. 01 for the left; +0.539 per SD, p<0. 01 for the right) and CDT (odds ratio (OR) 0.093, p< 0.05 for the left; OR) 0.120, p<0. 01 for the right) scores. PSV of left CCA (-0.205 per SD, p<0.05) and IMT (+42.536 per SD, p< 0.001) were associated with ADL. PSV of right CCA was associated with MMSE (+0.081 per SD, p<0.001). No significant relationship between ICA flow velocity and cognitive performance was observed. Our preliminary data show that common carotid artery flow velocity was associated with cognitive performance.

Focused examination of cerebral blood flow in peri-resuscitation: a new advanced life support compliant concept—an extension of the focused echocardiography evaluation in life support examination

Abstract Aim To introduce a new concept of the extension of focused echocardiography evaluation in life support (FEEL) with advanced life support (ALS)-compliant duplex sonography of the extracranial internal carotid artery (ICA) blood flow velocity for monitoring of cerebral blood circulation during peri-resuscitation. Concept and results With respect to pulseless electrical activity states, the question of adequate cerebral blood flow (CBF) cannot be answered by echocardiography alone. Pulse checks are unreliable. To build up a concept for assessing CBF, we analyzed duplex sonography workflow in three adults on the intensive care unit (postoperative, cardiogenic shock, cardiac standstill), and in simulated procedures. We decided to use duplex flow velocity of the ICA, for it is an accepted measurement for estimating CBF and it seems to be easy to obtain a window and interpretation during peri-resuscitation. The presence of an arterial blood flow pattern and an end-diastolic flow velocity of more than 20 cm/s, arbitrarily set, is considered to indicate sufficient CBF. The method of ICA flow velocity analysis during peri-resuscitation was tentatively added to the FEEL concept and is described with algorithm, workflow and three cases. This method may give an assist to answer the question, if CBF is sufficient, when myocardial wall motion is detectable in peri-resuscitation care. Conclusion This new concept of an ALS-conformed analysis of ICA blood flow velocity by duplex sonography may provide a simple, fast applicable and inexpensive method to qualitatively assess CBF in the peri-resuscitation setting.

Evaluation of cerebral blood flow volume using color duplex sonography in patients with untreated panic disorder

The aim of this study was to compare cerebral blood flow (CBF) using color duplex sonography in panic disorder and normal controls. We report 24 untreated patients and 20 healthy subjects. State-Trait Anxiety Inventory, Beck Depression Inventory, Beck Anxiety Inventory, and Symptom Check List-90 were completed on each subject. The internal carotid artery (ICA) and vertebral artery (VA) of both sides were explored with a 7.5-Mhz linear array transducer. CBF volume and mean ICA flow velocity were significantly higher in patients than normal subjects adjusted for age. However, we could not find a statistically significant difference in flow volume and velocity of VA and the sum of bilateral ICA volume between patients and controls adjusted for age. There was also no correlation between CBF volume and the other radiological data with STAI scores. In conclusion, we found that independent of anxiety levels, CBF volume has increased in panic disorder patients. In addition, color duplex sonography is a non-invasive and easily applicable technique and it is a preferable alternative to quantify CBF volume.

Positron Emission Tomographic Cerebral Perfusion Disturbances and Transcranial Doppler Findings among Patients with Neurological Deterioration after Subarachnoid Hemorrhage

Abstract OBJECTIVE After aneurysmal subarachnoid hemorrhage, approximately 30% of patients experience delayed neurological deficits, related in part to arterial vasospasm and dysautoregulation. Transcranial Doppler (TCD) ultrasonography is commonly used to noninvasively detect arterial vasospasm. We studied cerebral perfusion patterns and associated TCD indices for 25 patients who developed clinical signs of delayed neurological deficits. METHODS Patients were treated in a neurosurgical intensive care unit and were studied if they exhibited delayed focal or global neurological deterioration. Positron emission tomographic cerebral blood flow (CBF) studies and TCD studies measuring the mean flow velocity (FV) of the middle cerebral artery and the middle cerebral artery FV/internal carotid artery FV ratio (with the internal carotid artery FV being measured extracranially at the cranial base) were performed. Glasgow Outcome Scale scores were assessed at 6 months. RESULTS A markedly heterogeneous pattern of CBF distribution was observed, with hyperemia, normal CBF values, and reduced flow being observed among patients with delayed neurological deficits. TCD indices were not indicative of the cerebral perfusion findings. The mean CBF value was slightly lower for patients who did not survive (32.3 ml/100 g/min), compared with those who did survive (36.0 ml/100 g/min, P= 0.05). CONCLUSION Among patients who developed delayed neurological deficits after aneurysmal subarachnoid hemorrhage, a wide range of cerebral perfusion disturbances was observed, calling into question the traditional concept of large-vessel vasospasm. Commonly used TCD indices do not reflect cerebral perfusion values.

Positron Emission Tomographic Cerebral Perfusion Disturbances and Transcranial Doppler Findings among Patients with Neurological Deterioration after Subarachnoid Hemorrhage

After aneurysmal subarachnoid hemorrhage, approximately 30% of patients experience delayed neurological deficits, related in part to arterial vasospasm and dysautoregulation. Transcranial Doppler (TCD) ultrasonography is commonly used to noninvasively detect arterial vasospasm. We studied cerebral perfusion patterns and associated TCD indices for 25 patients who developed clinical signs of delayed neurological deficits. Patients were treated in a neurosurgical intensive care unit and were studied if they exhibited delayed focal or global neurological deterioration. Positron emission tomographic cerebral blood flow (CBF) studies and TCD studies measuring the mean flow velocity (FV) of the middle cerebral artery and the middle cerebral artery FV/internal carotid artery FV ratio (with the internal carotid artery FV being measured extracranially at the cranial base) were performed. Glasgow Outcome Scale scores were assessed at 6 months. A markedly heterogeneous pattern of CBF distribution was observed, with hyperemia, normal CBF values, and reduced flow being observed among patients with delayed neurological deficits. TCD indices were not indicative of the cerebral perfusion findings. The mean CBF value was slightly lower for patients who did not survive (32.3 ml/100 g/min), compared with those who did survive (36.0 ml/100 g/min, P = 0.05). Among patients who developed delayed neurological deficits after aneurysmal subarachnoid hemorrhage, a wide range of cerebral perfusion disturbances was observed, calling into question the traditional concept of large-vessel vasospasm. Commonly used TCD indices do not reflect cerebral perfusion values.

Breathing and brain blood flow during sleep in patients with chronic mountain sickness

Chronic mountain sickness (CMS) patients have lower arterial O2 saturation (SaO2) during sleep compared with healthy high-altitude residents, but whether nocturnal arterial O2 content (CaO2) and brain O2 delivery are reduced is unknown. We measured SaO2, CaO2, sleep-disordered breathing (SDB), and internal carotid artery flow velocity in 8 CMS patients, 8 age-matched healthy CMS controls, 11 healthy younger-aged Han, and 11 healthy younger-aged Tibetan male residents of Lhasa, Tibet (3,658 m). CMS patients spent a greater portion of the night in SDB (total no. of episodes of apnea, hypopnea, and hypoventilation) than did the CMS controls, young Han, or young Tibetans (15% vs. 5, 1, and 1%, respectively; P < 0.05) because of more frequent apnea and hypoventilation episodes and longer duration of all types of episodes. SDB and unexplained arterial O2 desaturation caused nocturnal SaO2 to be lower and more variable in CMS patients than in CMS controls or in younger-aged Han or Tibetan men. Average CaO2 was similar, but the CMS patients spent 29%, whereas the other groups spent < 4%, of the night at values < 18 ml O2/100 ml whole blood. Internal carotid artery flow velocity during wakefulness was similar in CMS patients and CMS controls despite higher end-tidal PcO2 values in the CMS patients. When contiguous sleep stages are compared, flow velocity rose from stage 2 to rapid-eye-movement sleep in both groups. Whereas flow velocity remained elevated from awake to rapid-eye-movement sleep in the CMS controls, it fell in the CMS patients. During episodes of SDB, internal carotid flow velocity increased in CMS controls but did not change in the CMS patients such that values were lower in the CMS patients than in CMS controls at the end and after SDB episodes. We concluded that SDB and episodes of unexplained desaturation lowered nocturnal SaO2 and CaO2, which, together with a lack of compensatory increase in internal carotid artery flow velocity, likely decreased brain O2 delivery in CMS patients during a considerable portion of the night.

Transcranial Doppler Monitoring in Head Injury

Eighty-six patients with head injuries with an admission Glasgow Coma Scale score between 3 and 12 were studied sequentially by transcranial and cervical Doppler sonography. On a subset of 26 patients, sequential autoregulation and CO2 reactivity testing was also performed. Patient characteristics and hemodynamic data were correlated and analyzed with respect to the final outcome. The internal carotid artery (ICA) and middle cerebral artery flow velocities followed a typical pattern. Both were depressed during the first 3 days after the trauma and then increased to a maximum between Days 5 and 7. The increase of the middle cerebral artery flow velocities was more pronounced than the increase of the ICA flow velocities, thus indicating some degree of vasospasm. The amount of subarachnoid hemorrhage on the initial computed tomography correlated with the average middle cerebral artery/ICA flow velocity ratio (r = 0.5). Subarachnoid hemorrhages on computed tomography and, to a lesser degree, subdural and intracerebral hematomas were correlated with an unfavorable outcome. Vasospasm remained subcritical, and no negative relationship to outcome could be identified. Hyperperfusion, as based on ICA flow velocities, and vasospasm were correlated with diminished vasoreactivity. However, disturbed vasoreactivities, particularly during the first days, were common and did not necessarily predict an unfavorable outcome.

Internal carotid arterial flow velocity during exercise in Tibetan and Han residents of Lhasa (3,658 m).

Cerebral blood flow increases with acute exposure to high altitude, but the effect of hypoxia on the cerebral circulation at rest and during exercise appears influenced by the duration of high-altitude exposure. To determine whether internal carotid artery flow velocity increased with exercise in long-term residents of high altitude and whether resting values and the response to exercise differed in lifelong vs. acclimatized newcomer male residents of high altitude, we studied 15 native Tibetan and 11 Han ("Chinese") 6 +/- 2-yr residents of Lhasa (3,658 m), Tibet Autonomous Region, China. Noninvasive Doppler ultrasound was used to measure internal carotid artery diameter, mean flow velocity, and, in combination, hemoglobin and arterial O2 saturation to assess cerebral O2 delivery. Tibetan and Han groups were similar in body size and resting internal carotid artery diameter, blood pressure, hemoglobin concentration, internal carotid artery mean flow velocity, and calculated cerebral O2 delivery. Submaximal exercise increased internal carotid artery mean flow velocity and cerebral O2 delivery in the Tibetan and Han subjects. At peak exercise, the Tibetans sustained the increase in flow velocity and cerebral O2 delivery, whereas the Hans did not. Across all exercise levels up to and including peak effort, the Tibetans demonstrated a greater increase in internal carotid artery flow velocity and cerebral O2 delivery relative to resting values than did the Hans. The greater cerebral O2 delivery was accompanied by increased peak exercise capacity in the Tibetan compared with the Han group. Our findings suggest that the cerebral blood flow response to exercise is maintained in Tibetan lifelong residents of high altitude.

Internal carotid flow velocity with exercise before and after acclimatization to 4,300 m

Cerebral blood flow and O2 delivery during exercise are important for well-being at altitude but have not been studied. We expected flow to increase on arrival at altitude and then to fall as O2 saturation and hemoglobin increased, thereby maintaining cerebral O2 delivery. We used Doppler ultrasound to measure internal carotid artery flow velocity at sea level and on Pikes Peak, CO (4,300 m). In an initial study (1987, n = 7 men) done to determine the effect of brief (5-min) exercises of increasing intensity, we found at sea level that velocity [24.8 +/- 1.4 (SE) cm/s rest] increased by 15 +/- 7, 30 +/- 6, and 22 +/- 8% for cycle exercises at 33, 71, and 96% of maximal O2 uptake, respectively. During acute hypobaric hypoxia in a decompression chamber (inspired PO2 = 83 Torr), velocity (23.2 +/- 1.4 cm/s rest) increased by 33 +/- 6, 20 +/- 5, and 17 +/- 9% for exercises at 45, 72, and 98% of maximal O2 uptake, respectively. After 18 days on Pikes Peak (inspired PO2 = 87 Torr), velocity (26.6 +/- 1.5 cm/s rest) did not increase with exercise. A subsequent study (1988, n = 7 men) of the effect of prolonged exercise (45 min at approximately 100 W) found at sea level that velocity (24.8 +/- 1.7 cm/s rest) increased by 22 +/- 6, 13 +/- 5, 17 +/- 4, and 12 +/- 3% at 5, 15, 30, and 45 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal carotid velocity measurements in children with cerebrovascular disease

Internal carotid artery flow velocity was evaluated by the Doppler ultrasound method in 32 children with cerebrovascular disease. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) were compared with each other as indices of blood flow velocity. The right and left mean A/L and d of moyamoya disease were significantly lower than those observed in normal children. The A/L and d of the affected side both in internal carotid artery occlusion and in middle cerebral artery occlusion were also significantly low. In the subarachnoid hemorrhage after rupture, these values were significantly low. In basilar artery occlusion, these values were similar to those in normal children. The results of this study indicate that Doppler ultrasound assessment of internal carotid flow velocity provides noninvasive reliable information for the diagnosis of cerebrovascular disease in childhood.

Changes in internal carotid artery flow velocities with cerebral vasodilation and constriction.

Non-invasive Doppler-shift ultrasound, together with spectral analysis, have been used to study the changes in internal carotid artery flow velocity patterns that occur with cerebral vasoconstriction and vasodilation provoked by over-breathing and breath-holding. Significantly different waveform shapes, characteristic for each vessel, were demonstrated from the internal and external carotid arteries, making identification of the internal carotid certain. In 5 healthy subjects over-breathing for 3 minutes significantly lowered the mean height of the internal carotid waveform by an average of 32% (p less than 0.001). Breath-holding for 40-60 seconds raised the mean height by an average of 31% (p less than 0.001). The pulsatility index of the waveforms varied inversely to mean height. These results show that the effects of cerebral dilation or constriction are easily detected by flow-velocity changes in the internal carotid artery.

Precerebral arterial blood flow pattern in intracranial hypertension with cerebral blood flow arrest.

A pulsed echo Doppler flowmeter was used to confirm cerebral flow arrest in patients with intracranial hypertension resulting in a cerebral perfusion pressure of zero or close to zero. The cerebral angiograms showed non-filling. The term brain tamponade is used for this condition. The patient had a mean arterial blood pressure at the time or recording ranging from 70 to 160 mmHg. Under these conditions the transcutaneous recording of internal carotid artery flow velocity immediately distal to the carotid bifurcation showed a reverberating flow pattern with marked pulsations. The forward flow in systole was counterbalanced by the retrograde flow during diastole resulting in a net flow of zero. This flow pattern is basically caused by a combination of intracranial vascular obstruction, the arterial blood pressure at the site of measurement, and finally the compliance of the distal arterial segment as well as the intracranial compliance. This non-invasive method is of potential value in the determination of intracranial flow arrest.