The effect of electrical stimulation on leg muscle pump activity in spinal cord-injured and able-bodied individuals.

The purpose of this study was to examine the difference in: (1) effective muscle pump activity (MPA) between voluntary and electrically (ES) induced contractions in able-bodied subjects (ABS); and (2) ES-induced MPA between spinal cord-injured (SCI) individuals and ABS. MPA was measured as relative volume changes in the calf using strain-gauge plethysmography during repeated muscle contractions in the supine position while venous outflow was impeded by a thigh cuff inflated to a range of pressures. Ten SCI individuals and ten ABS participated in this study. ABS showed no significant difference between voluntary and electrically induced MPA [58.1 (18.4)% versus 67.7 (8.7)%, respectively]. SCI individuals showed a significantly lower ES-induced MPA than ABS [21.5 (15.9)% versus 67.7 (8.7)%, respectively]. The low MPA in SCI individuals may be explained by: (1) extensive leg muscle atrophy and/or (2) an "atrophic" vascular system in the legs. The electrical current level seemed to influence MPA (43 mA, 21.5% versus 60 mA, 30.8%) for SCI individuals, whereas no influence of muscle contraction rate on MPA was observed in ABS. The results of this study demonstrate that although ES-induced leg muscle contractions result in adequate MPA in ABS, it leads to significantly less effective MPA in SCI individuals.

The postthrombotic syndrome in relation to venous hemodynamics, as measured by means of duplex scanning and strain-gauge plethysmography.

PURPOSE: Venous hemodynamics were evaluated in relation to the postthrombotic syndrome (PTS) 7 to 13 years after deep venous thrombosis (DVT). METHODS: The presence of flow, reflux, and compressibility of 1394 vein segments in 82 patients was assessed by means of duplex scanning. The venous outflow resistance was measured by means of strain-gauge plethysmography. The venous hemodynamics were related to the clinical severity of the PTS, characterized by the CEAP (clinical, etiologic, anatomic, pathophysiologic) classification. RESULTS: In patients with severe clinical symptoms of PTS, the prevalence of reflux was significantly higher. There was no relationship between the severity of the PTS and the noncompressibility or the combination of reflux and noncompressibility or an increased venous resistance. By means of multiple regression analysis with the variables of age, gender, reflux, and venous resistance, age and reflux were shown to be the main contributors to the severity of PTS. Significantly more patients (64%) with severe signs of PTS had a combination of deep and superficial reflux. In each of the traceable vein segments, the mean of the CEAP classification was calculated for the vein segments with and without reflux. In the proximal superficial femoral vein (P <.001), distal superficial femoral vein (P <.05), and popliteal vein (P <.05), a significantly higher mean CEAP classification was found in the veins with reflux, whereas in the distal, long, and short saphenous veins, no such relationship was found. CONCLUSION: Most patients with severe PTS had a combination of deep and superficial reflux. Reflux in the deep proximal veins contributes significantly to the PTS.

Venous duplex scanning of the leg: range, variability and reproducibility.

Despite the many studies on venous haemodynamics using duplex, only a few evaluated the normal values, variability and reproducibility. Therefore, the range and variability of venous diameter, compressibility, flow and reflux were measured. To obtain normal values, 42 healthy individuals (42 limbs, 714 vein segments) with no history of venous disease were scanned by duplex. To determine the reproducibility the intra-observer variability was measured in 11 healthy individuals (187 vein segments) and the inter-observer variability in 15 healthy individuals (255 vein segments) and 13 patients (169 vein segments) previously diagnosed with deep venous thrombosis. Of the 714 normal vein segments, 708 (99%) were traceable, including the crural veins. Of the traceable vein segments, 675 (95%) were compressible and in 696 (98%) flow was present. Of the 42 common femoral vein segments, in 25 (60%) the reflux duration exceeded 1.0 s, but in the other proximal vein segments the reflux duration was less than 1.0 s (95% confidence interval 3.0-10.0). With the exception of the distal long saphenous vein, in the distal vein segments the reflux duration was less than 0.5 s (95% confidence interval 3.5-8.2). The coefficient of variation of the diameter measurements ranged from 14 to 50% and that of the reflux measurements from 28 to 60%. The kappa-coefficient of the inter-observer variability in the classification of compressibility measurements in the patients was 0. 77 and that of the reflux measurements was 0.86. This study shows that almost all veins were compressible in healthy individuals, except the distal femoral veins. In healthy individuals the duration of reflux of the proximal veins was less than 1.0 s and in the distal veins it was less than 0.5 s. The inter-observer variability of the reflux and compressibility measurements in the patients was good.

Deep venous thrombosis: a prospective 3-month follow-up using duplex scanning and strain-gauge plethysmography.

1. The purpose of the study was to evaluate the degree of thrombus regression, development of valvular insufficiency, impaired calf muscle pump function and clinical symptoms after a period of acute deep venous thrombosis. 2. Seventy patients with acute deep venous thrombosis, diagnosed by duplex scanning or venography, received treatment with heparin and oral coumarin derivatives according to a standard protocol. All patients wore graduated compression stockings during the whole study period. Duplex scanning was performed at diagnosis and 1 and 3 months later to measure thrombus mass and reflux. The supine venous pump function test was used to assess calf muscle pump function. 3. Three months follow-up was completed in 60 patients. In total 218 (28%) out of 780 vein segments were initially thrombosed and 134 (17%) could not be traced. A statistically significant reduction of thrombus mass was recorded throughout the study period. Total resolution of thrombosis in all vein segments occurred in 25% of the patients within 1 month and in 40% in 3 months. There was no difference in regression between the various proximal vein segments. Distal segments showed more regression than proximal segments. Reflux occurred in 27% of the initially thrombosed veins and in 15% of the patent veins. Patients who showed total resolution after 1 month had a significantly higher calf muscle pump function than patients without total resolution (70%pf vs 61%pf, P < 0.05). Patients with reflux in two or more segments had a significantly lower calf muscle pump function than patients with reflux in less than two segments (58%pf vs 69%pf, P < 0.05). 4. Using duplex scanning and the supine venous pump function test 3 months after an acute deep venous thrombosis, overall haemodynamic abnormalities and local site of valve incompetence could readily be identified. Patients with haemodynamic abnormalities might be at risk to develop the post-thrombotic syndrome. There was no difference in thrombus regression between the various proximal vein segments. Reflux was significantly more often seen in initially thrombosed veins. Thirty-five percent of the patients developed an abnormal calf muscle pump function after 3 months. Patients with early resolution of thrombus had a higher calf muscle pump function after 3 months.

Changes in venous hemodynamics after renal transplantation.

To explain an occasionally observed transient swelling of the ipsilateral leg in renal transplant recipients in the absence of deep vein thrombosis, we took serial measurements of venous outflow resistance and duplex examinations of both legs. Fourteen recipients of a living related donor kidney graft were submitted to strain gauge plethysmography and duplex examination before transplantation and 1 and 6 weeks thereafter. Venous outflow resistance and venous flow were measured and the veins were assessed for thrombosis. Strain gauge plethysmography showed a significant increase in venous outflow resistance in the leg on the side of the renal transplant 1 week after transplantation [0.28 +/- 0.13 vs 0.40 +/- 0.15 mmHg.s (ml/100 ml)-1; P < 0.05]. Six weeks later, the venous outflow resistance had returned to preoperative values [0.30 +/- 0.11 mmHg.s (ml/100 ml)-1; P = NS]. On the contralateral side, no significant differences were found. Duplex examinations showed no signs of thrombosis. Venous flow measurements in the common femoral vein showed no significant differences. We conclude that the additional blood supply to the iliac veins results in an increase in venous outflow resistance in the ipsilateral leg, which can explain the observed swelling of this leg and may have implications for the preferred method of diagnosis of venous thrombosis after renal transplantation.

Duplex ultrasound in the hemodynamic evaluation of the late sequelae of deep venous thrombosis.

PURPOSE: The use of duplex ultrasound scanning to evaluate the hemodynamic outcome of deep venous thrombosis 7 to 13 years after the original diagnosis. METHODS: Duplex ultrasound was used to re-examine 1212 segments of vein from 72 patients (49 men, 23 women) with deep venous thrombosis previously diagnosed by means of phlebography to detect reflux and obstruction and evaluate flow; 611 segments were initially thrombosed and 601 segments were open. To define reflux, reversed flow in 31 healthy persons was measured. RESULTS: In a review of all veins of the 72 patients, 8 patients (11%) had completely normal duplex results in all veins, 33 (46%) had reflux, 6 (8%) had at least one noncompressible vein segment, and 25 (35%) had a combination of both. In the proximal vein segments without initial thrombosis a higher percentage was normal (73%) than in segments with initial thrombosis (46%). There was a significantly higher frequency of reflux (46%, p = 0.05) and noncompressibility (12%, p < 0.01) in initially thrombosed proximal vein segments than in vein segments without initial thrombosis (reflux 25%, noncompressibility 3%). Distal to the knee 125 (17%) of 720 vein segments were not traceable. Significantly more initially thrombosed vein segments were not traceable (p < 0.01). In distal vein segments there was no significant difference in reflux (7% versus 5%) and noncompressibility (10% versus 5%) between vein segments with and without initial thrombosis. Flow was present in 99% of the 611 previously thrombosed proximal and distal segments. CONCLUSIONS: Most patients with deep venous thrombosis still had venous abnormalities 7 to 13 years after the initial diagnosis. The most common abnormality was reflux. Significantly more abnormalities were found in initially thrombosed segments. The abnormalities were found in the proximal vein segments and in the distal vein segments, although less frequently in the latter.

Doppler spectrum analysis versus direct femoral artery pressure measurement for rapid assessment of aortoiliac obstruction.

Adequate patient selection is required to limit the clinical workload and improve the cost-effectiveness of noninvasive hemodynamic evaluation of the aortoiliac system. In a prospective blinded fashion the traditional invasive technique of direct femoral artery pressure measurements and the computerized Doppler spectrum analysis of blood flow velocities in the common femoral artery were studied. Both tests for rapid assessment of aortoiliac obstruction were compared with duplex ultrasonographic imaging, using a peak systolic velocity ratio of 2.5 to demonstrate stenoses of 50% or more. In a series of 17 consecutive patients (34 aortoiliac segments) with suspected aortoiliac obstructive disease, a good level of agreement (kappa = 0.6) was found for both methods when compared with duplex scanning. Analysis of deviations from the duplex registrations indicated an overestimation of the pathologic cases using femoral artery pressure measurements and an underestimation using Doppler spectrum analysis of blood flow velocities in the common femoral artery. Both methods were well tolerated, but femoral artery pressure measurements had a higher technical failure rate. Because of its noninvasive character and its feasibility the Doppler technique is preferred for the selection of patients for more extensive duplex sonographic investigation.

Clinical and haemodynamic sequelae of deep venous thrombosis: retrospective evaluation after 7-13 years.

1. In contrast to the extensive documentation on diagnosis and treatment of deep venous thrombosis (DVT), information about long-term complications, like the post-thrombotic syndrome (PTS), is scarce. Most studies report on clinical examination only, whereas adequate haemodynamic investigation is lacking. Therefore 81 patients with venographically confirmed lower extremity DVT were clinically and haemodynamically reexamined 7-13 years after DVT (mean 10 years) to assess PTS. Interest was focused on the relation between clinical and haemodynamic PTS and the relation between location of the initial DVT and incidence of PTS. 2. Clinical signs and symptoms of PTS were classified according to the latest consensus of the international consensus committee on chronic venous disease. Non-invasive venous vascular laboratory tests were performed to assess the venous outflow resistance and calf muscle pump function (CMP). CMP was determined by the supine venous pump function test (SVPT). 3. Clinically only 20 of 81 patients (25%) were asymptomatic, 34 (42%) had mild PTS (class 1-3), 25 (31%) moderate PTS (class 4) and 2 (2%) severe PTS (class 5-6); 57% had an abnormal CMP. Both the severity of clinical symptoms and the haemodynamic abnormalities were related to the location of the initial thrombus. Of the patients with distal DVT 11% developed moderate clinical PTS and 39% developed an abnormal CMP. CMP and difference in CMP between post-thrombotic and non-thrombotic leg were significantly related to the different classes of PTS. 4. This study indicates that 7-13 years after DVT 31% of the patients had moderate and 2% had severe clinical PTS, while 57% of the patients had abnormal haemodynamic findings (both related to the initial site of the thrombosis). Secondly, it reveals that the risk of PTS after distal DVT is not negligible, which causes concern about not diagnosing and treating patients with distal DVT. Thirdly, we have demonstrated that a functional test, such as the SVPT, is a sensitive test to assess post-thrombotic damage. Therefore its use as a screening tool after a period of DVT should be investigated to select patients at risk of PTS.

Decreased ankle/brachial indices in relation to morbidity and mortality in patients with peripheral arterial disease.

To determine the relationship between ankle/brachial indices (ABIs) and morbidity and mortality in patients with peripheral arterial disease (PAD), a historical cohort study was performed. A total of 154 patients who had undergone noninvasive arterial assessment of the lower extremities in 1989 and 1990 were selected for this purpose. Selection criteria were age > 40 years at the time of investigation, a resting ABI < 0.90 and the availability of an ABI after exercise or arterial occlusion. Mortality and vascular events were recorded after an average follow-up period of 6 years. A vascular event was defined as an intervention because of PAD, the occurrence of a nonfatal myocardial infarction or stroke, a transient ischaemic attack or a coronary artery bypass graft (CABG) or percutaneous transluminal coronary angioplasty (PTCA) procedure. During the period studied, 44 patients died and 111 patients suffered a vascular event. The relative risk for mortality was 3.1 per 0.50 decrease of the ABI at rest (95% confidence interval (CI) 1.1-8.7, p = 0.03) and 2.4 per 0.50 decrease of the ABI after exercise or arterial occlusion (95% CI 0.9-6.4, p = 0.08). The relative risk for mortality or the occurrence of a vascular event was 3.3 per 0.50 decrease of the resting ABI (95% CI 1.7-6.3, p < 0.001) and 2.5 per 0.50 decrease of the ABI after exercise or occlusion (95% CI 1.5-4.4, p < 0.001). After standardization, the prognostic power of the two types of ABIs was equivalent. The cumulative survival after 5 years was 63% for patients with resting ABIs < 0.50, 71% for patients with ABIs 0.50-0.69 and 91% for those with ABIs of 0.70-0.89. There were obvious differences between the mean initial ABIs of patients who suffered a vascular event and/or died and those of survivors, who did not suffer an event. A relatively simple measurement like the determination of the resting ABI can give valuable information about the prognosis for vascular related morbidity and mortality. This can be of help in the approach of patients with PAD and assist in therapeutical decision making. Determination of the ABI after exercise or occlusion has no additional value for this purpose.

Effect of apheresis of low-density lipoprotein on peripheral vascular disease in hypercholesterolemic patients with coronary artery disease.

BACKGROUND: Apheresis of low-density lipoprotein (LDL) is an effective lipid-lowering treatment in hypercholesterolemic patients who have coronary artery disease and are refractory to drugs. More aggressive lipid-lowering therapy may further slow the progression of atherosclerosis. OBJECTIVE: To compare the effect of LDL apheresis and simvastatin therapy with the effect of simvastatin therapy alone on the progression of peripheral vascular disease. DESIGN: Open, randomized, single-center study. SETTING: University hospital. PATIENTS: 42 men with primary hypercholesterolemia (total cholesterol level > 8.0 mmol/L) and extensive coronary atherosclerosis. INTERVENTION: Biweekly apheresis of LDL plus simvastatin, 40 mg/d (n = 21), or simvastatin, 40 mg/d (n = 21), for 2 years. MEASUREMENTS: Lipid and lipoprotein levels, changes in hemodynamically significant stenoses in the aortotibial tract (measured by ankle:arm systolic blood pressure ratio combined with Doppler spectrum analysis of the femoral artery), and changes in the mean intima-media thickness of three carotid artery segments. RESULTS: Mean baseline LDL cholesterol levels decreased from 7.8 to 3.0 mmol/L in the apheresis and simvastatin group and from 7.9 to 4.1 mmol/L in the simvastatin-only group; mean lipoprotein(a) levels decreased from 57.0 to 44.5 mg/dL (change, -19%) in the former group and increased from 38.4 to 44.5 mg/dL (change, 15%) in the latter group. In the apheresis group, the number of patients with hemodynamically significant stenoses in the aortotibial tract decreased from 9 to 7; in the simvastatin-only group, the number increased from 6 to 13 (P = 0.002). Mean intima-media thickness decreased by a mean +/- SD of 0.05 +/- 0.34 mm in the apheresis group and increased by 0.06 +/- 0.38 mm in the simvastatin-only group (P < 0.001). According to multiple regression analysis, changes in apolipoprotein B, total cholesterol, and lipoprotein(a) levels accounted for changes in the aortotibial tract (R2 = 0.36); changes in lipoprotein(a) and apolipoprotein A1 levels accounted for changes in the intima-media thickness of the carotid artery (R2 = 0.49). CONCLUSIONS: Aggressive lipid lowering with simvastatin and LDL apheresis decreased the intima-media thickness of the carotid artery and prevented an increase in the number of hemodynamically significant stenoses in the lower limbs. Therapy with simvastatin alone did not prevent progression of carotid or aortotibial vascular disease.

Validation of the supine venous pump function test: a new non-invasive tool in the assessment of deep venous insufficiency.

1. A new non-invasive test was developed to assess calf muscle pump function: the supine venous pump function test. The technique uses strain-gauge plethysmography and is performed in the supine position. The method is superior to other non-invasive methods because basically the most essential haemodynamic parameter, venous pressure decrease, is used by properly converting venous volume measurements into venous pressure. The validity of this test was established by comparison with invasive venous pressure measurements and by determining the reproducibility. Additionally, normal values were determined. 2. In 28 extremities the supine venous pump function test was performed simultaneously with invasive venous pressure measurements. The reproducibility of the test was assessed in 10 randomly chosen volunteers. In 34 volunteers normal values were obtained and 26 patients with clinical venous insufficiency were examined. 3. Comparison of the two methods revealed a correlation coefficient of r = 0.98 (P < 0.001). A mean difference of 3.9%pf between both methods was found with limits of agreement of -6.3%pf to 14.1%pf. The coefficient of repeatability was 13%pf and the coefficient of variation was 9%. The normal range was found to be > 60%pf. The mean pump function in the patient group was 45%pf. 4. The limits of agreement are small enough to be confident that the supine venous pump function test can be used instead of invasive venous pressure measurements to assess calf muscle pump function in clinical practice. The reproducibility of the test is good.

Doppler spectrum analysis in the differential diagnosis of renal transplant dysfunction.

Cyclosporin A (CyA) nephrotoxicity and rejection of a renal allograft each demands a specific therapy. This study was designed to establish the capability of Doppler spectrum analysis to diagnose either one of these causes during renal dysfunction. Between October 1989 and October 1991 we performed echo-Doppler examinations in 209 renal transplant recipients on a routine basis during the first three months after transplantation. Echo-Doppler examinations during periods of renal dysfunction were analyzed. A total of 93 periods of renal dysfunction, retrospectively due to rejection (n = 40) or CyA toxicity (n = 53), occurred in 70 patients during the study period. A control group consisted of 82 patients with normal functioning grafts. When compared to the control group, the Doppler features (in segmental arteries) of the rejection group showed significant lower frequency shifts [Fmax (Hz) 1637 +/- 423 vs. 1436 +/- 465; p < 0.05; Fdia (Hz) 582 +/- 180 vs. 458 +/- 225; p < 0.05], a shorter deceleration time of the Doppler spectrum [Tdown (ms) 340 +/- 100 vs. 276 +/- 102; p < 0.05], and a higher Resistance Index (RI 0.64 +/- 0.08 vs. 0.68 +/- 0.13; p < 0.05). Doppler spectra during CyA toxicity showed only a significantly longer acceleration time [Tmax (ms) 123 +/- 36 vs. 139 +/- 40; p < 0.05]. The capability of differentiation between the two causes was assessed with ROC analysis of single Doppler features, stepwise regression and canonic discriminant analysis on a set of Doppler features and with manual selection of several features with extreme values. ROC analysis yielded maximum sensitivity and specificity for the diagnosis of rejection using Tdown (sensitivity 65%; specificity 68%). Stepwise regression and canonic discriminant analysis of a set of features rendered a sensitivity and specificity of 73% and 64%, respectively. Explorative selection of extreme Doppler feature values showed that 18 of the 40 grafts with rejection had values that were only seen in 2 cases with CyA toxicity (positive predictive value 90%; sensitivity 45%; specificity 96%). In half of these cases Doppler features preceded the clinical diagnosis of rejection by a median of 4 d. In conclusion, Doppler spectra are influenced by rejection and CyA toxicity in specific ways. The Doppler features, however do not enable definite differentiation between rejection and CyA toxicity in all cases. Some changes in Doppler spectra are only seen in cases of rejection and thus enable positive identification of grafts with rejection, often earlier than clinical signs indicate rejection. A normal Doppler spectrum does not exclude rejection as the cause of renal dysfunction.

Diagnosis of deep vein thrombosis, an overview.

Because clinical signs and symptoms are unreliable the diagnosis of deep vein thrombosis (DVT) should be objectified. Advantages and disadvantages of contrast venography, plethysmography, ultrasound techniques, fibrinogen leg scanning, computer-assisted tomography, magnetic resonance imaging and blood tests are discussed. In patients with a first event of suspected DVT non-invasive methods like serial plethysmography or ultrasound testing are sensitive and specific enough to make a treatment decision. It is safe to withhold anticoagulants if the test remains normal within 1 week. In patients with suspected recurrent DVT new non-invasive techniques are being tested, but up to now the definitive objective diagnostic test continues to be contrast venography. In first period as well as in recurrent DVT D-Dimer testing could be an additional test to exclude active thromboembolism.

The prevalence of peripheral vascular disease in familial hypercholesterolaemia.

OBJECTIVES: In patients with familial hypercholesterolaemia (FH), the prevalence of haemodynamically significant peripheral vascular disease (PVD) was measured in relation to lipoproteins, general risk factors and the presence of coronary artery disease (CAD). DESIGN: A case control study. SETTING: The outpatient lipid clinic of a university hospital (tertiary referral centre). SUBJECTS: Patients with heterozygous FH [n = 68; age 45.8 +/- 11.6 years; untreated LDL-cholesterol 9.2 +/- 2.0 mmol L-1] were compared with control subjects matched for gender, age, weight, smoking and presence of hypertension [n = 27; age 44.0 years; LDL-cholesterol 3.8 +/- 1.3 mmol L-1]. MAIN OUTCOME MEASURES: PVD was assessed during cholesterol-lowering treatment using ankle/arm blood pressure ratios and analyses of Doppler-derived blood flow velocities in the femoral artery at rest and during reactive hyperaemia. The diagnosis of CAD was assessed clinically. RESULTS: Haemodynamically significant PVD was found in 21 (31%) FH patients and in one (3.7%) control subject, predominantly localized in the femoro-popliteal vessels. CAD was present in 30 (44.1%) FH patients and in one (3.7%) control subject. PVD could be demonstrated in 50% of FH patients with CAD [relative risk 3.2 (95% CI 1.4-7.2)] and in 19% as the first manifestation of vascular disease. Males and females were equally affected. Mean arterial blood pressure of FH patients with PVD was higher compared to FH patients without PVD. CONCLUSIONS: Haemodynamically significant PVD appears to be more prevalent in FH patients than is generally assumed, especially in those with CAD. A relation with lipoprotein levels could not be demonstrated.

Echo-Doppler diagnosis of renal allograft artery stenosis.

For the diagnosis of allograft artery stenosis in recipients of a renal transplant with hypertension a noninvasive investigation such as echo-Doppler is preferable to invasive methods such as angiography. Therefore we analyzed our experience with echo-Doppler diagnosis of renal allograft artery stenosis. In 131 renal transplant recipients with hypertension echo-Doppler examinations were performed. During the examinations several features indicative of stenosis were measured, and intrarenal Doppler spectra were quantitatively analyzed with a user-written program. Four patients showed signs of iliac artery stenosis. In 12 patients a renal allograft artery stenosis was suspected on echo-Doppler examination. In 8 of these 12 patients angiography was performed. All these showed a stenosis, 6 of which had more than > 75% stenosis. In 8 patients with normal echo-Doppler findings angiography was performed because of highly suggestive clinical signs of stenosis. In 7 of these no stenosis was found and in one a 50% stenosis was found. Comparison of quantitative Doppler spectrum features from patients with (n = 6) and without severe (> 75%) stenosis on angiography (n = 10) showed significant differences in several Doppler parameters. Subsequently an analysis of the best differentiation between these to groups on the basis of quantitative Doppler criteria was performed. In conclusion, echo-Doppler examinations with quantitative analysis of Doppler spectra enables reliable identification of renal allograft artery stenosis.

Properties of the venous vascular system in the lower extremities of individuals with paraplegia.

The purpose of this study was to examine the properties of the venous vascular system in the lower extremities of individuals with long-standing paraplegia (PP). The venous volume variations (VVV), the venous capacity (VC), the venous emptying rate (VER) and the venous flow resistance (VFR) were measured in the left calf of 14 male PP and 12 male able-bodied subjects (ABS) by means of strain-gauge occlusion plethysmography. VVV and VC were significantly lower in PP compared to ABS, -45% and -50% respectively. Both groups showed a similar resting venous pressure in the calf (PP = 24.4 mmHg; ABS = 19.6 mmHg). VER was significantly lower (-60%) and hence VFR was significantly higher (+75%) in PP compared to ABS. This study demonstrates that the venous vascular properties in the legs of individuals with paraplegia have changed, i.e. a decrease in venous distensibility and capacity and an increase in venous flow resistance. This is most probably the result of vascular adaptations to inactivity and muscle atrophy rather than the effect of a non-working leg-muscle pump and sympathetic denervation.

Doppler spectrum analysis to diagnose rejection during posttransplant acute renal failure.

During posttransplant acute renal failure (ARF), the diagnosis of allograft rejection constitutes a major problem. We evaluated the value of Doppler ultrasonography in identifying grafts at risk of rejection during ARF. In 184 recipients of a renal allograft, Doppler examinations were performed on the first and fifth postoperative day. Doppler spectra were quantitatively analyzed with a user-written computer program. Doppler findings were not used in clinical decision making. ARF was defined as a diuresis < 400 ml/24 hr and/or the necessity for dialysis. Doppler spectra obtained on the first day after transplantation showed a resistance index (RI) of 0.59 +/- 0.09 in recipients with immediately functioning cadaveric grafts (n = 123), while living related donor grafts (n = 20) showed a lower RI (0.55 +/- 0.07; P < 0.05). Grafts with ARF (n = 41) showed a considerably higher RI (0.67 +/- 0.13; P < 0.05). When grafts with a duration of ARF < or = 4 days (n = 17) were compared with ARF > 4 days (n = 24), RI was not significantly different (0.63 +/- 0.07 vs. 0.68 +/- 0.15; NS). However, the acceleration time of the systolic deflection of the spectrum waveform (Tmax) was shorter in grafts with ARF > 4 days (86 +/- 47 msec vs. 128 +/- 39 msec; P < 0.05). On the fifth day after transplantation, Doppler spectra in grafts with ARF > 4 days (n = 24) showed a Tmax < 90 msec in 9 patients, 8 of whom experienced rejection during ARF (positive predictive value, 8/9 = 89%). In the 15 patients with Tmax > or = 90 msec, only 2 rejections occurred (negative predictive value, 13/15 = 87%). For the RI (> 0.85), positive predictive value was 4/5 = 80% and negative predictive value (RI < or = 0.85) was 13/19 = 68%. In conclusion, a short acceleration time of the Doppler waveform on the first day after transplantation is associated with a longer duration of ARF. Quantitative analysis of Doppler spectra can be helpful in the identification of patients at risk for rejection and in the timing of allograft biopsy during ARF. Persistently short Tmax values on the fifth day after transplantation perform better in identifying grafts at risk of rejection than high RI values.

Importance of the coronary collateral circulation for the distribution of anterograde and retrograde delivered cardioplegic solution in aortocoronary bypass surgery: a haemodynamic study.

The importance of coronary collateral circulation for homogeneous distribution of anterograde and retrograde delivery of cardioplegia was evaluated in 36 patients undergoing myocardial revascularization. All patients had three-vessel coronary artery disease, with a stenosis of the right coronary artery of at least 80%. The patients were randomized into two groups: group A (n = 19) received anterograde delivered cardioplegic solution and group B (n = 17) received retrograde. Both groups were further subdivided depending on the pathology of the right coronary artery, as evaluated on preoperative coronary angiography. In group A1 (n = 8) and group B1 (n = 7) there was no visualization of collateral circulation from the left to the right coronary artery system, whereas in group A2 (n = 11) and group B2 (n = 10) there was retrograde filling of the right coronary artery by collateral circulation. Right atrial pressure increased significantly (P < 0.05) in group A1 and was elevated in group A2, but not significantly (P = 0.07). By contrast, right arterial pressure decreased in groups B1 and B2. Analysis of the individual differences in the right atrial filling pressure showed a statistical significance between the two subgroups (group B1-1.0(0.5) versus group B2-1.8(1.1), P < 0.05), although the individual decrease of the right ventricular stroke work index was not significant. It is concluded that collateral circulation is important for an adequate distribution of anterogradely delivered cardioplegia and is also beneficial in cases of retrograde delivery.

Sternal closure: comparison of two techniques.

A clinical trial was performed to evaluate sternal closure with the controlled tension osteosynthesis system and closure with twisted stainless steel wires. Some 451 consecutive patients who underwent isolated coronary bypass surgery between January 1991 and December 1991 were subdivided into three groups. Patients in group A (94 patients) and group B (98 patients) were all operated on by one surgeon, to reduce variability before, at the time of and after surgery, which might influence sternal wound healing. To exclude a possible preference of the surgeon in the study, group C was formed, consisting of 259 patients operated on by other hospital surgeons. In groups A and C, sternal closure was performed with the controlled tension osteosynthesis system. In group B, sternal closure was performed with (six) twisted stainless steel wires. Among groups A, B and C, no statistical significant difference could be found between the rate and the type of sternal wound complications. Despite this finding, there were significantly more reoperations, a longer cross-clamp time and more extensive use of the internal mammary artery as a graft in group B. Despite the non-randomization of the study, and the small patient numbers being a limitation, the use of the controlled tension osteosynthesis system in adults did not result in a decrease of early sternal wound complications.