Adult ; Carotid Artery, Internal ; pathology ; physiopathology ; Headache ; pathology ; physiopathology ; Humans ; Male ; Migraine Disorders ; pathology ; physiopathology

Carotid Artery, Internal ; physiology ; Carotid Body Tumor ; blood supply ; complications ; surgery ; Carotid Sinus ; physiopathology ; Female ; Humans ; Middle Aged ; Syncope ; etiology ; Syndrome

OBJECTIVESTo establish a theoretical model for the tortuosity of internal carotid artery and summarize the hemodynamic rule of blood flow in a tortuous artery. To explore the relationship of cerebral ischemia and tortuous internal carotid artery.

METHODSTaking the internal carotid artery as a prototype, a geometric model of a tortuous artery was constructed according to the normal physiological and anatomical parameters of internal carotid artery. The boundary conditions and calculation conditions of blood flow are proposed. The numerical simulation of the blood flow in the tortuous artery is carried out with finite element method. Hemodynamic parameters of internal carotid artery were measured in 15 cases with the tortuosity of internal carotid artery and in 15 cases of normal control group. Blood pressure was measured by microcatheter connecting a pressure transducer at internal carotid artery, pre-tortuous and post-tortuous artery. The diameter and length of the above artery were measured and calculated by DSA machine.

RESULTSNumerical simulation results indicated pressure drop of blood flow and elongated length of artery is increased with diminution of the angle of tortuous artery. Clinical measurement data disclosed the same trend in the same curve as numerical simulation.

CONCLUSIONThe elongation and tortuosity of internal carotid artery results in decrease of blood pressure in the distal segment of tortuous internal carotid artery, kinking of internal carotid artery may be one of factors related to attack of cerebral ischemia on certain conditions.

Adult ; Aged ; Brain ; blood supply ; Brain Ischemia ; etiology ; physiopathology ; Carotid Artery, Internal ; physiopathology ; Carotid Stenosis ; complications ; physiopathology ; Female ; Finite Element Analysis ; Hemodynamics ; Humans ; Male ; Middle Aged ; Models, Cardiovascular ; Regional Blood Flow

Carotid Artery, Internal ; diagnostic imaging ; Cerebrovascular Disorders ; diagnostic imaging ; physiopathology ; Extremities ; physiopathology ; Humans ; Ischemic Attack, Transient ; complications ; diagnostic imaging ; drug therapy ; Male ; Middle Aged ; Middle Cerebral Artery ; diagnostic imaging ; Thromboembolism ; diagnostic imaging ; physiopathology ; Ultrasonography, Doppler, Transcranial

PURPOSE: Although time-of-flight (TOF)-magnetic resonance angiography (MRA) can clearly depict intracranial arteries, the arterial flow of middle cerebral artery (MCA) is occasionally not detected. We evaluated this phenomenon with reference to cerebrovascular dynamics. MATERIALS AND METHODS: Seventeen patients with suspected occlusion of MCA or internal carotid artery on TOF-MRA were enrolled. All patients underwent CT angiography (CTA) and quantitative cerebral blood flow (CBF) examination for measurement of resting CBF and cerebrovascular reactivity (CVR). Depending on appearance, patients were categorized into three groups. Group A (n=6) had MCA delineation on both MRA and CTA, while groups B (n=6) and C (n=5) had no signal on MRA, but Group B had a MCA delineation on CTA.
Acetazolamide/administration & dosage ; Aged ; Aged, 80 and over ; Carotid Artery, Internal/physiopathology ; Cerebrovascular Circulation ; Computed Tomography Angiography ; Female ; Humans ; Magnetic Resonance Angiography ; Male ; Middle Aged ; Middle Cerebral Artery/diagnostic imaging

PURPOSE: We evaluated hemodynamic significance of stenosis on magnetic resonance angiography (MRA) using acetazolamide perfusion single photon emission computed tomography (SPECT). MATERIALS AND METHODS: Of 171 patients, stenosis in internal carotid artery (ICA) and middle cerebral artery (MCA) (ICA-MCA) on MRA and cerebrovascular reserve (CVR) of MCA territory on SPECT was measured using quantification and a 3-grade system. Stenosis and CVR grades were compared with each other, and their prognostic value for subsequent stroke was evaluated. RESULTS: Of 342 ICA-MCA, 151 (44%) presented stenosis on MRA; grade 1 in 69 (20%) and grade 2 in 82 (24%) cases. Decreased CVR was observed in 9% of grade 0 stenosis, 25% of grade 1, and 35% of grade 2. The average CVR of grade 0 was significantly different from grade 1 (p<0.001) and grade 2 stenosis (p=0.007). In quantitative analysis, average CVR index was -0.56+/-7.91 in grade 0, -1.81+/-6.66 in grade 1 and -1.18+/-5.88 in grade 2 stenosis. Agreement between stenosis and CVR grades was fair in patients with lateralizing and non-lateralizing symptoms (kappa=0.230 and 0.346). Of the factors tested, both MRA and CVR were not significant prognostic factors (p=0.104 and 0.988, respectively), whereas hypertension and renal disease were significant factors (p<0.05, respectively). CONCLUSION: A considerable proportion of ICA-MCA stenosis detected on MRA does not cause CVR impairment despite a fair correlation between them. Thus, hemodynamic state needs to be assessed for evaluating significance of stenosis, particularly in asymptomatic patients.
*Acetazolamide ; Adult ; Aged ; Aged, 80 and over ; Brain/blood supply/radionuclide imaging ; Carotid Artery, Internal/physiopathology/radionuclide imaging ; Carotid Stenosis/physiopathology/*radionuclide imaging ; *Cerebrovascular Circulation ; Constriction, Pathologic ; Diuretics ; Female ; *Hemodynamics ; Humans ; Hypertension/physiopathology ; Iodine Radioisotopes ; *Magnetic Resonance Angiography ; Male ; Middle Aged ; *Radiopharmaceuticals ; Tomography, Emission-Computed, Single-Photon/*methods