Carotid Artery Velocity Research Articles

84 INTRAOPERATIVE EVALUATION OF SURGICALLY CREATED A SYSTEMIC TO PULMONARY SHUNTS WITH PULSED DOPPLER ULTRASOUND

Pulsed Doppler ultrasound (PDU) blood velocity measurements in the carotid artery were compared with outcome of surgically created systemic-to-pulmonary shunts. In 9 shunt cases an 8 MHz PDU probe was placed over the ipsilateral carotid artery and flow velocity was recorded while the shunt was mechanically manipulated from open to closed. The following indices were derived from the velocity waveforms: integrated systolic velocity to integrated diastolic velocity ratio (DV/SV), end diastolic velocity to peak systolic ratio (EDV/PSV), and reverse velocity to'forward velocity ratio (R/F). The mean for each index for each patient was less during the shunt open state than the corresponding mean during the shunt closed state. A paired t test for each index showed significance levels of p<.01, p<.001, and p<025 for DV/SV, EDV/PSV, and R/F, respectively. The patient with the smallest difference between means of DV/SV and EDV/PSV for the open and closed states required shunt enlargement and the patient with the greatest difference between means required shunt reduction. The remaining 7 shunts were bracketed by these two end points and were deemed adequate at the two week follow-up exam. This preliminary data suggests that PDU velocity derived indices correlate well with shunt magnitude in the acute operative setting. Noninvasive PDU is potentially an inexpensive, convenient, repeatable, and safe alternative to aortography and cardiac catheterization in the assessment of shunt function.

Pulsed Doppler Evaluation of Diameter, Blood Velocity and Blood Flow of Common Carotid Artery in Sustained Essential Hypertension

Diameter, blood flow velocity, and volumic flow of the common carotid artery were measured in 38 patients with sustained essential hypertension and compared with those of 38 age-matched normal subjects. Both hypertensive and control subjects were classified according to age into those younger and those older than 45 years. For the determinations, a pulsed Doppler velocimeter with an adjustable range-gated time system and a double transducer probe was used. In the younger group, the diameter of the common carotid artery had a similar value in hypertensive patients (0.639 +/- 0.014 cm) and in controls (0.651 +/- 0.015). The same level of blood flow velocity in hypertensive patients (19.7 +/- 0.9 cm/s) and in controls (21.2 +/- 0.9 cm/s) was observed. Therefore, the volumic flow was equal in the common carotid artery of the hypertensive patients (385 +/- 20 ml/min) and of the normotensive subjects (410 +/- 23 ml/min). In the older group, blood flow velocity was reduced in the common carotid artery of the hypertensive patients (19.4 +/- 1.0 cm/s vs. 15.6 +/- 0.6 cm/s; p less than 0.01), but the diameter was unchanged (0.653 +/- 0.018 cm in hypertensive patients and 0.665 +/- 0.018 cm in controls). Thus, there was a significant reduction of volumic blood flow in common carotid artery of the hypertensive patients over 45 years (321 +/- 14 ml/min). A negative relationship was observed between common carotid artery blood flow and age in elderly hypertensive patients (r = -0.42; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ACTH on cerebral blood flow in children with intractable epilepsy

Cerebral blood flow was assessed by ultrasound in 12 children with intractable epilepsy who were treated with ACTH. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) of the internal carotid artery were measured, before, during and after ACTH therapy in each subject. The right and left mean A/L and d values were significantly decreased during ACTH therapy, and these values returned to the previous levels after the treatment. Cerebral function in children treated with ACTH may be affected by a decrease in cerebral blood flow.

Energetics of isometric contraction in porcine carotid artery.

The rate of ATP utilization ( JATP ) and unloaded shortening velocity ( Vus ) of porcine carotid artery were studied during tension development and maintenance to assess the importance of mechanisms proposed to account for its high economy of tension maintenance. Previous work from our laboratory established that the rate of O2 consumption ( JO2 ) can be used to measure rates of tissue phosphagen utilization as early as 30 s after initiation of contraction. Studies at 37 degrees C of tissue JO2 indicated the following. 1) The basal JO2 was 0.069 +/- 0.017 mumol O2 X min-1 X g-1) (n = 10). During steady-state tension maintenance suprabasal JO2 was 0.079 +/- 0.012 mumol O2 X min-1 X g-1 for tissues stimulated with KCl (n = 11) and 0.213 +/- 0.022 (n = 3) for tissues stimulated with KCl + histamine. 2) For both stimulation conditions an initial elevated (peak) suprabasal JO2 was observed that correlated with the rate of tension development. The peak suprabasal JO2 was approximately twice the steady-state suprabasal JO2 measured 10 min after stimulation. 3) There was no significant change in JO2 during tension redevelopment after a rapid length step at 15-20 min after stimulation (n = 4). Studies of Vus indicated the following. 1) During steady-state tension maintenance Vus was 0.008 +/- 0.001 tissue lengths/s for tissues stimulated with KCl (n = 13) tissue lengths/s for tissues stimulated with KCl + histamine (n = 6). 2) An initial twofold peak in Vus was observed at 0.25-0.5 min in that decreased to steady-state levels by 4 min after KCl stimulation, whereas minor decreases in Vus still occurred until 10-20 min after KCl + histamine stimulation. 3) The measured transient in Vus , although biphasic, does not temporally correlate with the transient in JO2 even after the JO2 time course was corrected for delays resulting from O2 diffusion and the electrode response time. The mechanism underlying the observed maximum change of two- to fourfold in both JATP and Vus is not sufficient to account for the high economy of tension maintenance.

Cerebral blood flow measured by doppler flow meter during petit mal seizure

We measured the cerebral blood flow velocity percutaneously using the Doppler ultrasound method while concurrently recording the EEG during seizures in two patients with petit mal epilepsy. The average maximal blood flow velocity (A/L) and end-diastolic blood flow velocity (d) of the internal carotid artery were measured. Somewhat increased A/L and d values were found at the onset of 3 Hz spike and wave bursts on EEG in one case. However, no increase or even reductions in A/L and d values were found during spontaneous petit mal seizures compared with interictal ones in the other case. These results are opposite to the previous other report.

Diagnosis of brain death by common carotid artery velocity waveform analysis.

In addition to neurologic criteria, some test of cessation of brain blood flow is recommended before diagnosing "brain death." Cerebral arteriography, radionuclide scintigraphy, and contrast computed axial tomography, though reliable, possess significant practical limitations. Analysis of the dimensions and contours of common carotid Doppler velocity tracings of brain-dead patients has identified qualitative and quantitative differences not only from normal subjects, but also from patients with complete atheromatous carotid occlusion and from those unconscious after brain injury. Though accurate separation was initially made using computer-assisted classification function analysis, a simplified algorithmic approach using only three velocity waveform variables has been developed without loss of accuracy. The speed, simplicity, portability, and inexpensiveness of this approach commend its use.

Internal carotid blood flow velocity in children with cerebral palsy by doppler ultrasound method

Cerebral blood flow assessed noninvasively by Doppler ultrasound technique in 30 children with cerebral palsy. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) of internal carotid artery were measured before and during brief digital compression of contralateral common carotid artery. Both A/L and d values in children with cerebral palsy were significantly lower than those observed in normal healthy children. In 13 children with spastic hemiplegia, no significant difference in either A/L or d was seen between the non-affected side and affected side both before and during brief digital compression. This data suggests that mean cerebral blood flow decreases in our children with cerebral palsy, and that no lateralization of the decrease in hemispheric cerebral circulation in hemiplegic children may explain by supposing the existence of generalized bilateral brain damage in those subjects.

Evaluation of carotid bifurcation disease: the role of common carotid artery velocity patterns.

We evaluated duplex ultrasonographic velocity patterns from the common carotid artery in 156 patients with arteriographically verified internal carotid artery disease. Flow to zero during diastole in the common carotid was found in three groups of patients: (1) those with flow to zero in both common carotids not related to disease of the carotid bulb; (2) those with a tight (90% to 99%) stenosis in the internal carotid; and (3) those with total occlusion of the internal carotid. Although such flow to zero is commonly observed with total occlusion of the internal carotid artery, it may also be seen with high-grade stenosis. Thus, when found, it is essential to ascertain if flow is indeed present in the internal carotid artery; understanding changes in velocity patterns of the common carotid has improved our overall accuracy in detecting extracranial carotid artery disease.

The Effects of Stellate Ganglion Block and Intravenous Administration of ATP on the Velocity of the Cerebral Blood Flow

The effects of the stellate ganglion block were investigated in 10 patients with sudden deafness, recording the blood flow pattern of the common carotid and the vertebral arteries by ultrasonic doppler method. Increased blood flow of the common carotid and vertebral arteries on the diseased side was demonstrated after the block of the diseased side.The effects of intravenous administration were investigated in 5 healthy persons by the same method. The velocity of the common carotid artery was increased after bolus injection of ATP, whereas both the velocities of blood flow of the common carotid and the vertebral arteries were increased after drip infusion of ATP.