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G Leftheriotis

Publications and source records attributed to G Leftheriotis.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of computational algorithms applied on transthoracic impedance waveforms to predict head-up tilt table testing outcome.

The goal of the present study was to develop and evaluate new algorithms for the prediction of the outcome of a head-upright tilt test (HUTT). Using transthoracic impedance and its first derivative, we attempted to determine if indexes computed on these waveforms could detect a positive outcome to a 70 degrees -45min HUTT with reliable sensitivity and specificity. The methods were evaluated retrospectively in a group of 70 patients and validated prospectively in a group of 59 patients. The best detector obtained used a neural network. It compares very favorably with published results for other syncope detectors.

Adolescent↗
PubMed2005

Systematic diagnostic approach to proximal-without-distal claudication in a vascular population.

BACKGROUND: Very few observations of proximal-without-distal claudication have been reported in the literature. This is likely due to the use of questionnaires limiting vascular claudication to the calves and to the problems encountered in attributing unexplained "buttock" claudication to a vascular origin. METHODS: During a 2 1/2-year period, we searched for proximal-without-distal exercise-related pain with the San Diego claudication questionnaire among some 2000 patients referred for lower limb arterial investigations. Of these patients, 97 presented no contraindication to treadmill testing and were investigated with exercise transcutaneous oxygen pressure (tcpO2). We used buttock tcpO2 (DROP index<-15 mm hg) to argue for the presence of ischemia on the corresponding side. RESULTS: Ischemia consistent with symptoms was found in 61 patients, whereas pain on one or both sides without underlying ischemia was found in 36 patients, suggesting a non-arterial origin of the symptoms. More than half of the patients with proximal-without-distal claudication and underlying exercise-related ischemia had been suffering for more than 2 years before they were referred to the laboratory. Eleven of the patients were treated. The treatment was successful in all but one of them. CONCLUSIONS: An important delay before diagnosis is frequently observed in proximal-without-distal claudication. TcpO2 is useful in attributing proximal exercise-related pain to a vascular origin. Given the number of detected and successfully treated patients in this small monocentric study, it is surprising that so few observations have been published to date, suggesting that proximal-without-distal arterial claudication is most likely an underestimated diagnosis.

Journal Article↗
PubMed2004

Reproducibility of proximal and distal transcutaneous oxygen pressure measurements during exercise in stage 2 arterial claudication.

AIM: Although transcutaneous oxygen pressure measurements (tcpO2) are largely used in the investigation of vascular patients, its reproducibility is still debated. Indeed an unpredictable gradient exists between arterial and transcutaneous oxygen pressure. We hypothesised that indices taking into account changes over time and independent of absolute starting values would be more reproducible than other indices. METHODS EXPERIMENTAL DESIGN: comparative test-retest procedure (1 to 13 days between tests). SETTINGS: institutional practice, ambulatory care. PATIENTS AND PARTICIPANTS: 15 subjects with stage 2 claudication. INTERVENTIONS: tcpO2 recordings at rest and at exercise during the 2 treadmill tests. MEASURES: calculation of the Delta-from-rest of oxygen pressure index (limb tcpO2 changes minus chest tcpO2 changes), of the resting - or minimal values attained during exercise - of absolute tcpO2 and of the regional perfusion index (regional perfusion index: ration of limb to chest). RESULTS: Both absolute tcpO2 and regional perfusion index at rest showed low reproducibility. During exercise the best reproducibility was attained through Delta-from-rest of oxygen pressure index calculation. Equations from the linear regression analysis (test 2 versus test 1) were 0.88 x -4.2 (r(2)=0.82) at the buttock level and 0.82 x -3.8 (r(2)=0.80) at the calf level. CONCLUSION: TcpO2 measurement on the calf or buttock during exercise, is a reproducible measurement in patients with vascular claudication, specifically when corrected for exercise-induced systemic pO2 changes trough Delta-from-rest of oxygen pressure calculation.

Aged↗
PubMed2003

Efficacy of pentasaccharide on a prethrombosis model based on a calibrated stasis by the increase in up-stream venous pressure.

On a previous model using Wessler's principle in the rat, we have demonstrated that a partial ligature of the inferior vena cava leading to a 40% increase in up-stream venous pressure was thrombogenic only in association with the infusion of low dose of thromboplastin (90 microg/kg). In these thrombogenic conditions, the infusion of pentasaccharide (Arixtra, fondaparinux) should lead to a strong inhibition of thrombus formation. Therefore, we performed on five groups of 10 rats: stasis alone (group S) with a 40% increase in up-stream venous pressure; stasis and thromboplastin (group ST90); and stasis, thromboplastin and pentasaccharide (groups SPT50, SPT100 and SPT250) at three different dosages (50, 100 and 250 microg/kg). The efficacy of pentasaccharide was measured according to the variations in up-stream venous pressure, thrombus weight and thrombin-antithrombin complexes levels. Only 250 microl/kg pentasaccharide significantly reduced the thrombus weight in comparison with group ST90 (5 mg versus 23.8 mg, P = 0.01) but it was not sufficient to induce a return to the basic state (5 mg versus 0.2 mg in group S, P = 0.049). Thrombin-antithrombin complex levels measured at the end of the experiment were significantly reduced in comparison with group ST90 (16.7 versus 57.8 mg, P = 0.01) and were not statistically different from group S (16.1 versus 16.6 mg, P = 0.65). In conclusion, in a very borderline model toward thrombogenesis, pentasaccharide was able to reduce thrombus weight and abolished biological hypercoagulability.

Animals↗
PubMed1998

Calf vein compliance increases following bed rest after aortocoronary bypass surgery.

Early post-operative ambulation (< 3 days) is expected to decrease the risk of venous thrombosis, whereas late ambulation (> 7 days) increases the risk of orthostatic hypotension. The effect of post-operative bed rest on calf vein compliance was studied before (D - 1) and 7 days (D + 7) after aortocoronary bypass surgery in 50 patients (41 men and nine women, 65 +/- SD 10 years). Calf vein compliance was measured by strain gauge plethysmography and stepwise increases in thigh congestive pressure from 20 to 60 mmHg. Calf compliance [median (25 percentile-75 percentile)] increased significantly by 48% from D - 1 to D + 7 [0.044 (0.039-0.051) vs. 0.065 (0.048-0.083) ml (100 ml mmHg)-1, P < 0.001]. This increase was reflected as increased calf volume for the 50 mmHg [D-1 2.10 (1.75-2.65) vs. D + 7 2.60 (1.70-3.00) ml 100 ml-1, P < 0.01] and 60 mmHg [D - 1 2.50 (2.10-2.95) vs. D + 7 3.20 (2.30-4.00) ml 100 ml-1, P < 0.001] occlusion pressure levels. The associated pathologies (diabetes and arterial hypertension) and NYHA grades had no significant influence on the increase in compliance. Among the vasoactive therapeutic regimens, calcium channel blockers contributed significantly to the increased calf compliance, but only on D-1. The increase in venous compliance following aortocoronary bypass surgery is multifactorial but should be considered for prophylactic management of these patients.

Aged↗
PubMed1998

Autoregulation of human inner ear blood flow during middle ear surgery with propofol or isoflurane anesthesia during controlled hypotension.

UNLABELLED: We used controlled hypotension to obtain a bloodless cavity during middle ear surgery under an optical microscope. No previous study has assessed the effect of controlled hypotension on inner ear blood flow (IEF) autoregulation in humans receiving propofol or isoflurane anesthesia. In the present study, the IEF autoregulation was determined using laser Doppler flowmetry in combination with transient evoked otoacoustic emissions (TEOAEs) during controlled hypotension with sodium nitroprusside in 20 patients randomly anesthetized with propofol or isoflurane. A coefficient of IEF autoregulation (Ga) was determined during controlled hypotension, with a Ga value ranging between 0 (no autoregulation) and 1 (perfect autoregulation). During controlled hypotension with propofol, IEF remained stable (1%+/-6%; P > 0.05) but decreased by 25%+/-8% with isoflurane (P < 0.05). The Ga was higher during propofol anesthesia (0.62+/-0.03) than during isoflurane anesthesia (0.22+/-0.03; P < 0.0001). Under propofol anesthesia, there were individual relationships between TEOAE amplitude and change in IEF in four patients. Such a correlation was not observed under isoflurane anesthesia. These results suggest that human IEF is autoregulated in response to decreased systemic pressure. Furthermore, isoflurane has a greater propensity to decrease cochlear autoregulation and function than propofol. IMPLICATIONS: The present study shows that inner ear blood flow is autoregulated under propofol, but not isoflurane, anesthesia during controlled hypotension in humans during middle ear surgery. Further studies are needed to explore the postoperative auditory functional consequences of the choice of the anesthetic drug used in middle ear surgery.

Adult↗
PubMed1998

Cerebral hemodynamics during carotid massage in patients with carotid sinus syndrome.

The effect of cardioinhibition and/or vasodepression on cerebral hemodynamics assessed by transcranial Doppler has been investigated during carotid massage in 11 patients (62-87 years, mean age 72) with carotid sinus syndrome. The patients were tested in the OOO mode (n = 11) with six tested in the DDD mode. Carotid massage in the OOO mode decreased mean arterial pressure by 44% (P < 0.01) and mean cerebral blood flow velocity by 50% (P < 0.01). Although not significant, cerebrovascular resistance increased transiently by 17% during massage, then decreased by 31% upon recovery. Carotid massage in the DDD mode decreased arterial pressure by 30% (P < 0.01), cerebral blood velocity by 23% (P < 0.01), and resistance by 15% (P < 0.05). The decreased cerebral perfusion induced by cardioinhibition and/or vasodepression results from the delayed onset of cerebral autoregulation. Pacing in the DDD mode temporarily assists the critical period preceding the onset of cerebral autoregulation that plays a key role in preventing the deleterious effects of vasodepression.

Aged↗
PubMed1998

Laser Doppler flowmetry in the diagnosis of chronic compartment syndrome.

Chronic compartment syndrome (CCS) is usually considered to be due to ischaemia of muscle. We have attempted to use the direct measurement of muscle blood flow for diagnosis since the assessment of intracompartmental pressure does not provide accurate knowledge of the vascular state. We recorded simultaneously continuous measurements of the laser Doppler flow (LDF) in muscle and the intracompartment pressure (ICP) after exercise in seven patients with CCS, and in seven control subjects. The mean ICP was 74.1 +/- 4.4 mmHg in CCS patients and 24.2 +/- 3.4 mmHg in control subjects one minute after exercise, decreasing to 34.6 +/- 2.3 mmHg and 15.0 +/- 1.6 mmHg at 20 min, respectively. The LDF was 0.80 +/- 0.11 arbitrary units (AU) in control subjects and 1.09 +/- 0.14 AU in CCS patients one minute after exercise, and 0.41 +/- 0.11 AU and 0.27 +/- 0.04 AU, respectively, at the end of the recovery period. The ICP showed a progressive decrease over time in both groups. The LDF decreased sharply during the first minutes of recovery in control subjects, but in patients with CCS there was a delayed hyperaemic peak with blood flow reaching 0.84 +/- 0.10 AU at nine minutes as against 0.33 +/- 0.06 AU for control subjects (p < 0.01). The ICP increased in both control subjects and CCS patients after exercise with no clear cut-off point between the groups. By contrast, changes in muscle blood flow over time were clearly different between control subjects and patients with CCS. For this reason, LDF should be investigated further as a technique for the diagnosis of CCS.

Chronic Disease↗
PubMed1997

Effects of positive pressure on both femoral venous and arterial blood velocities and the cutaneous microcirculation of the forefoot.

OBJECTIVE: The balance between the apparent beneficial effect and the risk of arterial ischaemia resulting from an external uniform compression is unclear. The purpose of this study was to determine the effects of a positive uniform compression on the lower limb circulation until a critical threshold was reached. METHODS: We used Doppler ultrasound to measure femoral venous and arterial blood velocities. The effects of positive pressure on cutaneous microcirculation were evaluated by laser Doppler flux (LDF), transcutaneous oxygen pressure (tcpO2) and transcutaneous carbon dioxide pressure (tcpCO2) on the forefoot of 17 healthy subjects. RESULTS: The results are expressed as median [lowest observed value-highest observed value]. Whereas the arterial femoral velocity (A.F.V.) decreased from 0.21 [0.08-0.36] to 0.17 [0.08-0.28] m s-1 for an external pressure as low as 10 mmHg (p < 0.001), the venous femoral velocity (V.F.V.) decreased from 0.13 [0.06-0.40] to 0.09 [0.05-0.34] m s-1 at 20 mmHg (p < 0.001). An increase of tcpCO2 from 39.8 [29.9-53.7] to 40.2 [30.0-55.5] mmHg (p < 0.05) and a decrease of LDF from 8.7 [3.1-25.9] to 5.5 [2.3-21.1] A.U. (p < 0.001) occurred at 10 mmHg. However, tcpO2 decreased only from 76.7 [40.2-91.2] to 64.6 [18.9-85.2] mmHg when the splint pressure reached 60 mmHg (p < 0.05). The observed parameters (LDF, tcpO2, V.F.V. and A.F.V.) decreased further (except for tcpCO2 which increased) up to the end of the study as the applied pressure was increased. CONCLUSION: Positive pressure on the full leg provided no significant beneficial effect on femoral venous blood velocity. Whereas we showed that for an external uniform pressure as low as 10 mmHg, significant impairments in both arterial inflow of the lower limb and microcirculation of the forefoot appeared in recumbent healthy young subjects.

Adult↗
PubMed1997

Prolonged asymptomatic micro-embolism after hip or knee arthroplasty.

We studied the time course of micro-embolism by recording high intensity transient signals (HITS) on Doppler venous blood flow studies during a 7-day period in 57 of 63 consecutive patients after hip or knee replacement. No HITS were found before surgery, or in the non-operated leg after surgery. In the operated leg, the median number of HITS per minute showed an exponential decrease with time; a 50% reduction in the number of HITS took 72 minutes. Regardless of the duration and severity of HITS, we found no clinically apparent embolic event. Colour Doppler imaging at days 8 to 10 after operation showed a deep venous thrombosis in 17% of our patients with one thrombosis of the long saphenous vein. The presence or severity of HITS did not predict the venous thrombi. Although we found no pulmonary complications, we detected micro-emboli over a longer period after surgery than is usually reported. Spectral analysis of the Doppler venous signal is a repeatable and non-invasive monitoring technique in the post-surgical period. We failed to prove a correlation between deep venous thrombi and micro-emboli detected by this method.

Aged↗
PubMed1997

[Isolated plantar venous thrombosis. Report of a case].

We report the case of a patient with isolated plantar thrombophlebitis as a post operative complication of saphenectomy. Risk factors such as prolonged bed rest, perioperative inflammation and surgery of the greater saphenous vein itself should be considered. Moreover multiple episodes of superficial venous thrombosis had already occurred as complication of the superficial venous insufficiency. Literature on this unusual outcome is lacking. Ultrasound imaging revealed this superficial thrombosis. Usual echographic signs (non compressible vein, hypoechogenicity of the vessel lumen) can be found. The main problem is to differentiate veins from adjacent tendinous structures. Slow mobilisation of the toes and comparative analysis on contralateral foot are helpful. Thrombosis of the plantar veins must be considered as a possible diagnosis of unexplained plantar unilateral pains. Development of ultrasonic investigations and knowledge of its occurrence could further improve its diagnosis.

Female↗
PubMed1996

Ankle to arm index following maximal exercise in normal subjects and athletes.

Recent reports have suggested that minor arterial lesions can be responsible for claudication in athletes occurring only during maximal exercise. Ankle to arm index measurements (AAI) prove the arterial origin of this claudication, but little is known about the normal response of AAI to maximal exercise. Therefore, we studied the response of AAI to maximal exercise in trained and untrained normal subjects. AAI and heart rate (HR) were recorded at rest and following maximal exercise on a cycle ergometer in 15 untrained (VO2 = 41.5 +/- 4.0 ml.kg-1.min-1) and 15 trained (VO2 = 58.4 +/- 2.8 ml.kg-1.min-1) volunteers. All subjects were without known peripheral arterial disease. At rest, AAI was 1.08 +/- 0.08 in untrained subjects and 1.15 +/- 0.05 in trained subjects (P < 0.05). HR was 73.9 +/- 11.0 in untrained subjects and 57.1 +/- 8.3 in trained subjects (P < 0.05). Following exercise, AAI decreased during the first minutes of recovery in all subjects, with a significant difference between untrained and trained subjects. Although untrained subjects sustained a lower workload than trained subjects, at 1 min following exercise AAI was 0.70 +/- 0.06 in untrained versus 0.8 +/- 0.08 in trained subjects (P < 0.05). No difference in AAI to HR relationships was noted between untrained and trained subjects. In conclusion, we suggest that AAI should be interpreted with regard to HR at the end of maximal exercise and we project normal results for the AAI to HR relationships following maximal exercise.

Adolescent↗
PubMed1996

Ankle to arm index response to exercise and heat stress in healthy subjects.

Ankle to arm index (AAI) defined as the ratio of ankle systolic blood pressure (ASBP), to brachial systolic blood pressure is largely used in the study of lower extremity arterial disease (LEAD). To study the hypothesis of the shunt of blood away from the skin as the explanation of AAI decrease in exercise, we studied the AAI and ASBP responses to an increase in cardiac output originating from an increase either in muscle blood flow (exercise) or in cutaneous blood flow (thermal stress). Brachial systolic pressure, ankle systolic pressure and heart rate (HR) were measured in 9 healthy subjects at rest, during heart thermal stress and following maximal exercise on a cycle ergometer. Compared to resting values, AAI decreased in all subjects from 1.05 +/- 0.07 to 0.75 +/- 0.07 (P < 0.05) 1 min following exercise and from 1.08 +/- 0.07 to 0.94 +/- 0.05 (P < 0.05) during heat stress. On the other hand, HR increased from 72.8 +/- 12.2 to 112.4 +/- 19.6 (P < 0.05) min following exercise and from 75.5 +/- 13.6 to 96.8 +/- 15.3 (P < 0.05) during heat stress. Since a comparable relation exists between AAI and HR in thermal stress and exercise, we suggest that the decrease in AAI in normal subjects following exercise is due to turbulences at high flow levels, rather than the shunting of blood to active muscles in exercise.

Adult↗
PubMed1995

Cerebral blood flow and resistances during hypotensive haemorrhage in the rabbit: transcranial Doppler and laser-Doppler flowmetry.

Transcranial Doppler (TCD) determined cerebral blood flow velocity and laser Doppler flowmetry (LDF) measured cortical perfusion were simultaneously assessed during hypotensive haemorrhage in 15 anaesthetized rabbits. Systolic (Fsys), diastolic (Fdia) and mean (Fmean) blood flow velocities were recorded into the intracranial internal carotid (ICA) and basilar artery (BA). Resistance (RI = Fsys-Fdia/Fsys) and pulsatility (PI = Fsys-Fdia/Fmean) indices were calculated. Step decreases of 10 mmHg of mean arterial pressure (MAP) from 80 to less than 30 mmHg provoked a fall of LDF signal below 50 mmHg. Blood velocities decreased into BA below 40 mmHg, and below 50 mmHg into ICA indicating regional differences in cerebral autoregulation. Cortical resistances (resLDF = MAP/LDF) fell below 60 mmHg whereas RI and PI increased when MAP decreased into BA below 40 mmHg and ICA below 50 mmHg. A weak correlation was found between Fmean and LDF (BA: r = 0.55, P < 0.01 and ICA = 0.46, P < 0.01). Both RI and PI were poorly correlated to resLDF into BA (RI-resLDF: r = -0.39, P < 0.01; PI-resLDF: r = -0.39, P < 0.01) and ICA (RI-resLDF: r = -0.18, ns; PI-resLDF: r = -0.22, ns). Pulse pressure (systolic-diastolic pressure) correlated with RI (ICA: r = -0.62, P < 0.001; BA: r = -0.61, P < 0.001) and PI (ICA: r = -0.61, P < 0.001; BA: r = -0.62, P < 0.001). In conclusion, during haemorrhagic shock, TCD correlates with LDF and indicates regional differences in autoregulatory settings. However, Doppler indices do not reflect the changes in cerebral resistances because they are influenced by the changes in pulsatile pressure.

Anesthesia↗
PubMed1995

Heart rate-corrected ankle-to-arm index in the diagnosis of moderate lower extremity arterial disease.

UNLABELLED: Although the ratio of ankle-to-arm systolic pressures (AAI) at rest is widely used in the clinical diagnosis of peripheral arterial disease, the heart rate (HR) at which the measurements are performed is rarely reported. The relation of ankle-to-arm index (AAI) to HR was studied in a normal population (n = 65) and in a population of patients (n = 101) suspected of moderate lower extremity arterial disease (LEAD). In the normal population, a significant inverse correlation was found between AAI and HR at rest: AAI = -0.277 x HR/100 + 1.303; r = -0.52, P < 0.001. In the second population suspected of LEAD, the authors recorded AAI and HR at rest on both legs; 80 normal legs, 110 diseased legs. Thereafter, with normal limits as superior to 0.8, 0.9, and 0.95, sensitivity was respectively 16, 39, and 46%, and specificity was 100, 100, and 98%. In defining normal limit as superior to -2 standard deviations of the AAI-HR relation found in the normal population, sensitivity and specificity were 57 and 100%, respectively. IN CONCLUSION: In screening for LEAD in the general population with the use of AAI at rest, the authors suggest that the heart rate at which arterial pressure measurements are performed should be reported.

Adult↗