(1/358) Contrast transcranial Doppler ultrasound in the detection of right-to-left shunts. Reproducibility, comparison of 2 agents, and distribution of microemboli.
BACKGROUND AND PURPOSE: Cardiac right-to-left shunts can be identified by transcranial Doppler ultrasound (TCD) with the use of different contrast agents and by transesophageal echocardiography (TEE). Systematic data are available on neither the reproducibility of contrast TCD, the comparison of different contrast agents, nor the comparison of simultaneous bilateral to unilateral recordings. Furthermore, we assessed the side distribution of thus provoked artificial cardiac emboli. METHODS: Fifty-four patients were investigated by TEE and by bilateral TCD of the middle cerebral artery. The following protocol was performed twice: injection of 9 mL of agitated saline without Valsalva maneuver, injection of 9 mL of agitated saline with Valsalva maneuver, injection of 5 mL of a commercial galactose-based contrast agent without Valsalva maneuver, and injection of 5 mL of the galactose-based contrast agent with Valsalva maneuver. RESULTS: In 18 patients, a right-to-left shunt was demonstrated by TEE and contrast TCD (shunt positive). Twenty-nine patients were negative in both investigations, 1 was positive on TEE and negative on TCD, and 6 patients were only positive on TCD. Both bilateral and repeated recordings increased the sensitivity of contrast TCD. There was a symmetrical distribution of microembolic signals in the right and left middle cerebral artery. CONCLUSIONS: TCD performed twice and with the use of saline or a galactose-based contrast agent is a sensitive method in the identification of cardiac right-to-left shunts also identified by TEE. The cardiac microemboli in this study did not show any side preference for one of the middle cerebral arteries. (+info)
(2/358) Physiological reflux and venous diameter change in the proximal lower limb veins during a standardised Valsalva manoeuvre.
OBJECTIVES: the aim of this study was to provide normal values for venous diameter at rest, and venous diameter and physiologic venous reflux during a standardised Valsalva manoeuvre. The impact of the patient's sex, body mass index (BMI), and family history was investigated. MATERIAL AND METHODS: eighty legs of 40 healthy volunteers were investigated in a supine position. The median age was 28 years (range 20-66 years). The common femoral vein (CFV), the proximal superficial femoral vein (SFV) and the proximal long saphenous vein (LSV) were investigated by duplex sonography. The following parameters were assessed: resting diameter (VDrest) and maximum diameter (VDmax) as well as reflux time (tr) during the Valsalva manoeuvre. The Valsalva manoeuvre was elicited by a forceful expiration into a tube system. The standard values used were a pressure of 30 mmHg, established within 0.5 seconds (s) and maintained over a time period of at least 3 s. RESULTS: mean VDrest and VDmax were 8.3+/-2.2 and 11.1+/-2.8 mm in the CFV, 5.9+/-1. 3 and 7.2+/-1.6 mm in the SFV and 3.5+/-0.9 and 4.3+/-1.4 mm in the LSV. Mean values for tr were 0.61+/-0.63 s in the CFV, 0.25+/-0.26 s in the SFV and 0.28+/-0.40 s in the LSV. A BMI >22.5 kg/m2 was associated with statistically significant larger values for VDrest and tr. If adjusted for BMI, tr in the SFV and the LSV did not differ by sex. For healthy subjects with first-degree relatives suffering from varicose veins (n=19), mean VDrest in the SFV as well as VD in the LSV was significantly larger (p=0.02, 0.05, respectively). Coefficients of variation for repeated measurements (VDrest, VDmax, tr) in the same segment varied between 3.3% and 16. 4% for the three investigated sites. CONCLUSIONS: normal values for VDrest and VDmax as well as reflux time during a standardised Valsalva manouevre were assessed in the proximal lower limb veins. The influences of BMI, sex and family history were investigated. The described standardised Valsalva manoeuvre led to highly reproducible results and can be recommended for further research projects or as a routine procedure for the assessment of venous reflux. (+info)
(3/358) Methodological parameters influence the detection of right-to-left shunts by contrast transcranial Doppler ultrasonography.
BACKGROUND AND PURPOSE: Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the contrast transcranial Doppler examination in the detection of right-to-left shunts. METHODS: A total of 72 patients (mean age, 58.2+/-14.7 years) had a contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the contrast medium, and the patient's posture during the examination. RESULTS: The median contrast signal count was 58.5 and 48.0 (P<0.001) and the median latency of the first intracranially detected contrast signal was 12.5 and 8.5 seconds (P=0.05) when the Valsalva maneuver was performed 5 and 0 seconds after the start of the injection, respectively. Reducing the contrast medium dose from 10 to 5, 2.5, and 1.2 mL resulted in a decline of the median signal count from 54.5 to 28.5, 20.5, and 12.0 (P<0.01), respectively, while the latency of the first contrast signal increased from 13.3 to 14.0, 14.6, and 15.0 seconds (P<0.05). The sitting position also produced a lower signal count than the supine position (P<0.02). CONCLUSIONS: This study demonstrates that several essential methodological parameters influence the results of the contrast transcranial Doppler ultrasonography examination. Therefore, it is necessary to standardize the procedure to permit comparable quantitative assessments of the shunt volume. The findings of the present study suggest that 10 mL of contrast medium be injected with the patient in the supine position and that the Valsalva maneuver be performed 5 seconds after the start of the injection. (+info)
(4/358) Ultrasonographic diagnosis and color flow Doppler sonography of internal jugular venous ectasia in children.
We investigated the diagnostic utility of ultrasonography in the diagnosis of internal jugular venous ectasia. Eight children (six boys, two girls) were recruited into this prospective study. Sonography of internal jugular venous ectasia in these patients revealed fusiform dilation of the internal jugular vein, and the possibility of thrombus and external compression could be ruled out. Marked variation in size of ectatic jugular veins during respiration was demonstrated under real-time sonography. The mean anteroposterior diameter of these dilated internal jugular veins was 0.79+/-0.18 mm (mean+/-standard deviation), which increased to 1.58+/-0.27 mm with Valsalva maneuver. Our study showed that the anteroposterior diameters of the internal jugular veins in cases of ectasia were greater than those of contralateral jugular veins in same patients as well as those in normal children, and they showed greater increase after Valsalva maneuver. Under color Doppler flow studies, turbulent vascular flows were demonstrated in these patients with jugular venous ectasia. No progression of venous ectasia was found in any of our patients during a 6 month follow-up period. We conclude that internal jugular venous ectasia in children is a benign condition, which usually does not require surgical intervention. Ultrasonography is a good diagnostic modality for the diagnosis of internal jugular venous ectasia. Color Doppler ultrasonography demonstrate the turbulent flow in jugular venous ectasia. (+info)
(5/358) Acute manipulations of plasma volume alter arterial pressure responses during Valsalva maneuvers.
The effects of changes in blood volume on arterial pressure patterns during the Valsalva maneuver are incompletely understood. In the present study we measured beat-to-beat arterial pressure and heart rate responses to supine Valsalva maneuvers during normovolemia, hypovolemia induced with intravenous furosemide, and hypervolemia induced with ingestion of isotonic saline. Valsalva responses were analyzed according to the four phases as previously described (W. F. Hamilton, R. A. Woodbury, and H. T. Harper, Jr. JAMA 107: 853-856, 1936; W. F. Hamilton, R. A. Woodbury, and H. T. Harper, Jr. Am. J. Physiol. 141: 42-50, 1944). Phase I is the initial onset of straining, which elicits a rise in arterial pressure; phase II is the period of straining, during which venous return is impeded and pressure falls (early) and then partially recovers (late); phase III is the initial release of straining; and phase IV consists of a rapid "overshoot" of arterial pressure after the release. During hypervolemia, early phase II arterial pressure decreases were significantly less than those during hypovolemia, thus making the response more "square." Systolic pressure hypervolemic vs. hypovolemic falls were -7.4 +/- 2.1 vs. -30.7 +/- 7 mmHg (P = 0.005). Diastolic pressure hypervolemic vs. hypovolemic falls were -2.4 +/- 1.6 vs. -15.2 +/- 2.6 mmHg (P = 0.05). A significant direct correlation was found between plasma volume and phase II systolic pressure falls, and a significant inverse correlation was found between plasma volume and phase III-IV systolic pressure overshoots. Heart rate responses to systolic pressure falls during phase II were significantly less during hypovolemia than during hypervolemia (0.7 +/- 0.2 vs. 2.82 +/- 0.2 beats. min-1. mmHg-1; P = 0.05) but were not different during phase III-IV overshoots. We conclude that acute changes in intravascular volume from hypovolemia to hypervolemia affect cardiovascular responses, particularly arterial pressure changes, to the Valsalva maneuver and should be considered in both clinical and research applications of this maneuver. (+info)
(6/358) Older subjects show no age-related decrease in cardiac baroreceptor sensitivity.
OBJECTIVE: To examine the relationship between age, blood pressure and cardiac baroreceptor sensitivity derived from spectral analysis, the Valsalva manoeuvre and impulse response function. METHODS: We studied 70 healthy normotensive volunteers who were free from disease and not taking medication with cardiovascular or autonomic effects. We measured beat-to-beat arterial blood pressure and used standard surface electrocardiography to record pulse interval under standardized conditions with subjects resting supine as well as during three Valsalva manoeuvres. We performed single, multiple and stepwise regression of patient characteristics against cardiac baroreceptor sensitivity results. RESULTS: There is a non-linear decline in cardiac baroreceptor sensitivity with advancing age, increasing systolic blood pressure and heart rate values (except for the Valsalva-derived result), but little further decline after the fourth decade. Only age significantly influenced values derived using the Valsalva manoeuvre and impulse response analysis. Using spectral analysis, age, systolic and diastolic blood pressure and heart rate influenced cardiac baroreceptor sensitivity, age contributing to 50% of the variability. Age also influenced the relationship between pulse interval and blood pressure, possibly indicating more non-baroreceptor-mediated changes with advancing age. CONCLUSIONS: Although age is the dominant factor influencing cardiac baroreceptor sensitivity in this normotensive population, there is little change in mean values after 40 years of age. The differences in the relationship between pulse interval and blood pressure with advancing age have implications for the calculation of cardiac baroreceptor sensitivity using spectral analysis. (+info)
(7/358) Contrast transcranial Doppler ultrasound in the detection of right-to-left shunts: comparison of different procedures and different contrast agents.
BACKGROUND AND PURPOSE: Cardiac right-to-left shunts can be identified by transesophageal echocardiography (TEE) and by transcranial Doppler ultrasound (TCD) with the use of different contrast agents and different provocation procedures. Currently, data on an appropriate time window for the appearance of contrast bubbles in the TCD recording after the injection of the contrast medium and the comparison of different provocation maneuvers to increase right-to-left shunting are insufficient. METHODS: Forty-six patients were investigated by both TEE and bilateral TCD of the middle cerebral artery. The following protocol with 6 injection modes was applied in a randomized way: (1) injection of 10 mL of agitated saline without Valsalva maneuver, (2) injection of 10 mL of agitated saline with Valsalva maneuver, (3) injection of 10 mL of a commercial galactose-based contrast agent (Echovist) without Valsalva maneuver, (4) injection of 10 mL of Echovist with Valsalva maneuver, (5) injection of 10 mL of Echovist with standardized Valsalva maneuver, and (6) injection of 10 mL of Echovist with coughing. RESULTS: In 20 patients, a right-to-left shunt was demonstrated by TEE and contrast TCD (shunt-positive). Sixteen patients were negative in both investigations, no patient was positive on TEE and negative on TCD, and 10 patients were only positive on at least 1 TCD investigation but negative during TEE. The amount of microbubbles detected in the various tests decreased in the following order: Echovist and Valsalva maneuver, Echovist with coughing, Echovist and standardized Valsalva maneuver, saline with Valsalva maneuver, Echovist, and saline. With a time window of 20 to 25 seconds for the bubbles to appear in the TCD recording and with a sequence of first Echovist and Valsalva maneuver and then Echovist with coughing, all shunts were reliably identified with a specificity of 65% compared with TEE as the traditional gold standard. The time of first microbubble appearance was not helpful to distinguish between shunts detected on TEE and other shunts. CONCLUSIONS: TCD performed twice with 2 provocation maneuvers using Echovist is a sensitive method to identify cardiac right-to-left shunts also identified by TEE. (+info)
(8/358) The effect of pregnancy on the lower-limb venous system of women with varicose veins.
OBJECTIVES: to assess the effect of pregnancy on the lower-limb venous system of women with varicose veins. Design a longitudinal prospective study of 11 pregnant women, with varicose vein disease. METHODS: eleven pregnant women with varicose veins were recruited as part of a larger study. Veins were assessed in both lower limbs using colour-flow duplex scanning at a 75 degrees head-up tilt. The diameter and velocity and duration of reflux were measured in each vein at 12, 20, 26, 34, 38 weeks gestation and 6 weeks postpartum. RESULTS: eleven women had reflux and varicose veins demonstrated at first scan. All veins dilated with increasing gestation. This was maximal in the superficial system, reaching significance (p=0.05) in the right long saphenous, superficial femoral and posterior tibial veins, left long and short saphenous, popliteal, peroneal, anterior and posterior tibial veins. The velocity of reflux increased while the duration decreased with increasing gestation. This was most obvious in the long saphenous veins but did not reach statistical significance. CONCLUSIONS: maximum changes were seen in the superficial venous system in the thigh. The effect was more pronounced on the left and the changes in reflux returned to pre-pregnancy levels in the puerperium. (+info)