Retrograde blood flow in the aortic arch determined by transesophageal Doppler ultrasound.

BACKGROUND: Aortic arch atheromas may be important sources of cerebral embolism. Aortic plaques are frequently found somewhat distal to the origin of the cerebral arteries, implying that cerebral embolization from such plaques depends on local retrograde blood flow components in this area. Therefore, we investigated the occurrence of blood flow reversal in this part of the aorta. Furthermore, since the presence and magnitude of retrograde flow might be influenced by aortic wall properties, we also studied the relationship between plaque size and distribution, aortic strain and degree of retrograde flow. METHODS: We evaluated aortic arch ante- and retrograde blood flow velocities in 56 patients by transesophageal echocardiography using color-Doppler-guided pulsed-Doppler techniques. The velocity-time integrals (VTI) were measured and the diastolic/systolic VTI ratio was calculated. RESULTS: Retrograde diastolic blood flow was noted in all subjects, and diastolic/systolic VTI ratios were higher (p < 0.05) in patients with plaque >or=4 mm (n = 17) compared to those (n = 39) without. Patients exhibiting plaques exclusively in the aortic arch showed the highest VTI ratios (p < 0.01) and tended to have the lowest strain values. Aortic strain was also reduced in patients >50 years of age (p < 0.01). CONCLUSIONS: Our findings demonstrate retrograde aortic flow in all subjects and its proportion increases in subjects with atherosclerosis, particularly in the aortic arch. Aortic plaques situated distally to the origin of the cerebral arteries are therefore possible sources of cerebral emboli.

[Hip implant revision. Avoiding mistakes and managing risk]. / Implantatrevisionen am Hüftgelenk. Fehlervermeidung und Risikomanagement.

Hip revision surgery may lead to unexpected complications, with a negative impact on the treatment outcome. To refer to possible difficulties as"mistakes" is less helpful than defining ways to foresee such difficulties and developing possible strategies to avoid them. This approach requires a comprehensive amount of personal experience, which may follow consideration of some basic"rules" and possible surgical scenarios before an intervention. The author presents an individual risk management approach that includes hints on how to foresee the occurrence of certain intraoperative difficulties and how to help avoid errors by incorporating forward-thinking strategies into hip revision surgery.

Effect of varicose vein surgery on venous reflux scoring and plethysmographic assessment of venous function.

BACKGROUND: Colour duplex ultrasonography (CDU) is widely recommended before varicose vein surgery, combined with quantification of venous reflux by plethysmography where required. This study assessed venous haemodynamics before and after varicose vein surgery by venous outflow plethysmography (VOP), venous reflux plethysmography (VRP) and by adoption of a modified segmental venous reflux score (VRS). The effect of wearing one or two class I medical compression stockings was also assessed. The aim of the study was to identify parameters which reflect the outcome of treatment using medical compression stockings or surgical intervention. METHODS: 24 legs of 21 patients with superficial vein incompetence of clinical grade C(2-4a) (CEAP) were assessed before and a mean of 8 S.D. 4 months after superficial vein surgery. Investigations were CDU, as well as VOP and VRP using mercury in rubber gauges fitted either around the calf or the forefoot. Venous reflux was semi-quantitatively graded by CDU in relation to the actual vein diameter and transformed into a VRS with respect to the number of involved serial vein segments. The venous reflux rates were measured in standing patients after knee bending before and after application of one or two superimposed compression stockings (class I). RESULTS: According to VRP, one compression stocking reduced the maximum venous reflux rates (VR(max)) by about 30% which was comparable with the effect of surgery on VR(max). Two superimposed compression stockings were almost twice as effective and diminished VR(max) pre- and post operatively by around 60%. Varicose surgery reduced the maximum venous outflow rates significantly (pre-op: 166 S.D. 77 ml/min x 100 ml tissue, post op: 120 S.D. 34) and improved VRS (pre-op median 5.0 IQR: 4.5-5.5, post-op median 0.5 IQR: 0-1.0). Surgery had no effect on venous refilling time or venous reflux rates when measured without compression stockings. CONCLUSION: Venous reflux assessed by plethysmography was moderated by the use of compression stockings pre-operatively but did not reflect the outcome of surgical treatment of superficial venous reflux. Increased venous volume and venous outflow were restored to the levels of normal contralateral limbs by surgery. The VRS decreased considerably following surgery, reflecting the effect of surgical treatment on the number of incompetent venous segments. Changes in this parameter did not correlate with any of the plethysmographic measurements.

Prevalence of micro-emboli in symptomatic high grade carotid artery disease: a transcranial Doppler study.

BACKGROUND AND PURPOSE: Echolucent carotid plaques, as well as downstream micro-embolisation, may be associated with an increased risk of stroke. However, the relationship between carotid plaque ultrasound characteristics and micro-embolic signals (MES) detected in the middle cerebral artery (MCA) is still controversial. The purpose of this study was to investigate the prevalence of MES in patients with symptomatic high-grade internal carotid artery (ICA) stenosis and to identify predisposing factors, such as plaque echogenicity and intra stenotic blood flow velocity pattern. METHODS: 197 patients (mean age 69.5+/-8.6, 161 males) with confirmed symptomatic high-grade ICA stenosis and anti-platelet treatment underwent bilateral MES monitoring for 30 minutes within the anterior circulation, using Power M-mode transcranial Doppler techniques (TCD). Carotid artery plaques were characterized by Gray-Weale scaling. RESULTS: In 32.0% of the patients, we detected MES by TCD within the MCA on the symptomatic side, but the same finding was made in only 4.5% on the corresponding asymptomatic site (p<0.0001). The presence or absence of MES was associated with neither ultrasonic plaque characteristics nor the intrastenotic blood flow velocities at peak systole and end diastole. The median time since the last ischemic event symptoms was shorter in the patient group with MES [+] than in MES [-] (p=0.013). CONCLUSIONS: Despite optimum standard anti-platelet therapy, cerebral micro-embolisation occurs in 30% of patients with symptomatic carotid artery disease, which might therefore be a possible risk factor for recurrent neurological symptoms. However, the presence of MES is independent of intrastenotic blood flow disturbances and grey scale ultrasound plaque characteristics. The presence of MES as an indicator of unstable plaque and thereby a possible risk factor for stroke should be evaluated prospectively using various algorithms for plaque classifications.

Actions of novel antidiabetic agent englitazone in hyperglycemic hyperinsulinemic ob/ob mice.

The effects of CP 68722 (racemic englitazone) were examined in ob/ob mice, in adipocytes and soleus muscles from ob/ob mice, and in 3T3-L1 adipocytes. Administration of englitazone at 5-50 mg.kg-1.day-1 lowered plasma glucose and insulin dose dependently without producing frank hypoglycemia in either the diabetic or nondiabetic lean animals. The glucose-lowering effect in ob/ob mice preceded the reduction in hyperinsulinemia. On cessation of drug, plasma insulin returned to untreated levels within 48 h, whereas plasma glucose rose slowly over 5 days. Englitazone (50 mg/kg) for 11 days lowered plasma glucose (22.2 +/- 1.4 to 14.0 +/- 1.9 mM), insulin (7.57 +/- 0.67 to 1.64 +/- 0.60 nM), nonesterified fatty acids (1813 +/- 86 to 914 +/- 88 microM), glycerol (9.20 +/- 0.98 to 4.94 +/- 0.03 mM), triglycerides (1.99 +/- 0.25 to 1.03 +/- 0.11 g/L), and cholesterol (6.27 +/- 0.96 to 3.87 +/- 0.57 mM), but no effects were observed 3 h after a single dose. Basal and insulin-stimulated lipogenesis were enhanced in adipocytes from ob/ob mice treated with 50 mg/kg englitazone for 11 days compared with lipogenesis in cells from vehicle-treated controls. Treatment of ob/ob mice with 50 mg/kg englitazone reversed the defects in insulin-stimulated glycolysis (from [3-3H]glucose) and glycogenesis and basal glucose oxidation (from [1-14C]glucose) in isolated soleus muscles. Englitazone (30 microM) stimulated 2-deoxy-D-glucose transport in 3T3-L1 adipocytes from 0.37 +/- 0.03 to 0.65 +/- 0.06 and 1.53 nmol.min-1.mg-1 protein at 24 and 48 h, respectively. Thus, englitazone has 1) insulinomimetic and insulin-enhancing actions in vitro and 2) glucose-, insulin-, triglyceride-, and cholesterol-lowering properties in an animal model of non-insulin-dependent diabetes mellitus (NIDDM) in which sulfonylureas have little or no effect. Thus, this new agent may have beneficial effects including a reduced risk of hypoglycemia in patients with NIDDM.

Adaptation of human atrial muscle repolarisation after high rate stimulation.

We analysed the effect of a sudden change from a high rate of stimulation to a "physiological" rate upon the repolarisation of human atrial muscle. Microelectrode technique was used to study the effect upon the action potential (AP) recorded from myocardial specimens obtained during open heart surgery in nine patients. Suction electrodes were used to record monophasic action potentials (MAPs) in 12 patients undergoing electroconversion of atrial fibrillation. The abrupt change from 30 min of high-rate stimulation of the atrial specimen to a pacing rate of 60 per min resulted in a successive prolongation of the atrial myocardial AP duration so that 50% of the prolongation was reached after 3 min according to an exponential analysis. A similar prolongation of repolarisation was seen in the MAP recordings after conversion of atrial fibrillation to sinus rhythm and during regular atrial stimulation at a rate of 100 per min. In these recordings, the time needed to reach 50% of the prolongation of the MAP after DC conversion was about 7 min. The findings demonstrate that human atrial muscle undergoes an adaptation of repolarisation after abrupt slowing from a fast stimulation rate. A steady-state level of the AP or MAP duration is reached 10 to 15 min after the change of rate. Together with earlier studies, these experiments indicate, that when right atrial MAP recording is done for assessment of the likelihood of the patient's remaining in sinus rhythm after conversion of atrial fibrillation, the recording must be made within a few minutes of the conversion.

Cerebral atherosclerosis as predictor of stroke and mortality in representative elderly population.

BACKGROUND AND PURPOSE: The aim of this study was to assess the relationship between cardiovascular risk factors, atherosclerotic disease in the carotid bifurcation, and the risk of stroke and mortality in a representative population sample. METHODS: One hundred forty-two men and women participated in a population study at ages 70 and 76 years. At age 78, extracranial and intracranial circulation was examined by means of duplex sonography and transcranial Doppler techniques. Mortality and hospitalization for stroke were analyzed over a 5-year follow-up period up to age 83 years. RESULTS: Carotid plaques were identified in 82% of the men and 79% of the women. Bilateral plaques were found in 57% of the men and 46% of the women, and stenosis resulting in >50% diameter reduction occurred in 28% of the men and 17% of the women. Carotid stenosis >75% was observed in 7 subjects (0.5%). Bilateral plaques at age 78 were correlated with systolic blood pressure and ischemic heart disease at age 70 years. The pulsatility index was 1.0 to 1.4 in 63% and > or =1.5 in 13% of the study population. The pulsatility index was correlated with systolic and diastolic blood pressure, serum cholesterol, and triglycerides. Men with bilateral carotid plaques at age 78 years had an increased risk of stroke or mortality during the 5-year follow-up period (74% bilateral plaques versus 21% unilateral or no plaques). This was not found in the women (33% versus 26%). CONCLUSIONS: Carotid atherosclerosis was prevalent in a majority of elderly subjects. Bilateral plaques were correlated with systolic blood pressure and ischemic heart disease at age 70 years and predicted the risk of stroke and mortality in men but not in women.

Norepinephrine overflow and renin pattern of the individual kidney in patients with unilateral renal artery stenosis.

This study was performed to determine divided renal efferent sympathetic nerve activity from kidneys in seven patients with renin-positive, unilateral renal artery stenosis before and 30 minutes after an acute intravenous dose of 1.25 mg enalaprilat. Renal norepinephrine release was calculated from split renal plasma flow, venoarterial plasma concentration gradients across the kidney, and the fractional extraction of tritiated norepinephrine. All patients had unilateral renin secretion, the affected kidney increasing its plasma renin activity gradient 1.7-fold, whereas no statistically significant change was noted on the contralateral side in response to enalaprilat. Total norepinephrine release to plasma and norepinephrine plasma clearance (assessed by isotope dilution) were similar before and after administration of enalaprilat (approximately 400 ng/min and 1.0 l/min), despite a 26% fall in mean arterial pressure (from 125 mm Hg, p less than 0.01). Heart rate remained unchanged. After enalaprilat, norepinephrine venoarterial difference increased in the renin-secreting kidney (from 264 to 396, SED = 57 pg/ml, p less than 0.05), whereas it increased only slightly in the contralateral kidney (from 149 to 256, SED = 72 pg/ml, NS). Tritiated norepinephrine extraction fell approximately 25% (p less than 0.01) in both kidneys. Thus, renal norepinephrine spillover increased from 49 to 62, SED = 9 ng/min (NS) and from 81 to 129, SED = 17 ng/min (p less than 0.05) from the affected and the contralateral kidney, respectively. Hence, in this relatively small study in patients with renovascular hypertension, no evidence for increased renal nerve activity could be observed in the affected kidney, despite its marked renin production.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive ultrasound assessment of renal artery stenosis by means of the Gosling pulsatility index.

OBJECTIVE: To gauge the effectiveness of a new Doppler test for renal artery stenosis (RAS), based on the pulsatility index of the blood flow velocity spectrum within several interlobar arteries of both kidneys. METHODS: Twenty normotensive volunteers and 49 hypertensive patients were investigated with ultrasound. Patients with angiographic signs of RAS underwent bilateral renal vein catheterization for renin measurement. Significant RAS was assumed if lateralization of renal vein renin to the stenotic side was proven. RESULTS: The pulsatility index was higher in the hypertensives without RAS than in normal volunteers. Side differences between both kidneys were within methodological variations with the exception of one case, in whom side difference was > 0.12. The pulsatility index was lower in kidneys with significant RAS than in kidneys without RAS. In most patients with significant unilateral RAS the side difference was < 0.12. In the other patients with a low pulsatility index and a side difference < 0.12 RAS was found to be bilateral upon angiography. Doppler signals were absent in all kidneys with renal occlusion. CONCLUSIONS: A side difference of > or = 0.12 predicts unilateral RAS, whereas the absence of parenchymal Doppler signals indicate occlusive RAS. A low pulsatility index combined with normal side difference may, in hypertensive patients, indicate bilateral RAS. Renovascular hypertension was correctly diagnosed in 84% of the patients and the presence of RAS in 94%.

Renovascular resistance in primary hypertension: experimental variations detected by means of Doppler ultrasound.

OBJECTIVE: To gauge the influence of renovascular resistance changes on blood flow velocity pulsatility in kidneys of hypertensive patients by means of the ultrasonic colour and pulsed-wave Doppler method, since we have previously shown in normotensive subjects that the blood flow velocity pulsatility in renal interlobar arteries varies with changes in renovascular resistance. METHODS: In six male patients with primary hypertension, renal blood flow velocity profiles were investigated by means of duplex ultrasound. Single-kidney renovascular resistance was assessed by measurements of split renal function (gamma-camera renography), renal plasma flow (steady-state para-aminohippurate clearance) and cuff blood pressure. The pulsatility index of the blood flow velocity spectrum in the renal interlobar artery and renovascular resistance were measured either at rest, during infusion of angiotensin II, or after angiotensin converting enzyme inhibition. RESULTS: A significant correlation existed between pulsatility index and renovascular resistance (r = 0.50, P < 0.002), which did not improve after correction for the blood pressure pulsatility. Changes of pulsatility index were more closely related (r = 0.64, P < 0.001) to the corresponding changes in renovascular resistance. CONCLUSIONS: With the two-dimensional image-guided colour and pulsed-wave Doppler method it is possible to assess semiquantitatively small intra-individual changes in renovascular resistance in hypertensive patients by means of pulsatility index measurements. Pharmacologically induced alterations in renovascular haemodynamics may therefore be evaluated with this technique.

Substituted dihydrobenzopyran and dihydrobenzofuran thiazolidine-2,4-diones as hypoglycemic agents.

A series of dihydrobenzofuran and dihydrobenzopyran thiazolidine-2,4-diones (compounds 3-26) was synthesized from the corresponding aryl aldehydes 1 in two steps. These compounds represent conformationally restricted analogues of the novel hypoglycemic ciglitazone. The series was evaluated by hypoglycemic effects in vitro by measuring stimulation of 2-deoxyglucose uptake in L6 myocytes and stimulation of expression of the glucose transporter protein in 3T3-L1 adipocytes. In vivo hypoglycemic effects were evaluated in the genetically obese ob/ob mouse, and structure-activity relationships are discussed. On the basis of this in vivo potency, we have selected the 2(R)-benzylbenzopyran derivative to be further studied in a clinical setting.

Biosynthesis of D-amino acid-containing peptides: exploring the role of peptide isomerases.

The discovery of D-amino acid residues in a growing number of gene-encoded peptides suggests that such biochemical modifications are more common than initially thought. In fact, the extent to which D-amino acids are incorporated into peptides by multicellular organisms probably has not been fully realized, since routine Edman sequencing does not provide the absolute stereochemistry of amino acid residues. Unless both the D and L isomers of a particular peptide sequence are isolated, D-amino acid-containing peptides are often identified only after synthesis of naturally-occurring peptide fails to yield the desired activity. To date, D-amino acid residues (e.g., alanine, methionine, leucine, isoleucine, phenyl alanine, asparagine, tryptophan and serine) have been identified in peptides from a variety of species, including frogs, snails, clams, lobsters and spiders. While most have a single D-amino acid residue located near their N-termini, an exception is found with omega-Aga IVB. The examples highlighted in this chapter are the result of a unique strategy of multicellular organisms to circumvent stereochemical limitations imposed by the genetic code in an effort to increase molecular diversity. The presence of D-amino acids permits the generation of novel tertiary structure that could not be accessed from L-amino acids alone. Moreover, advantages of increased potency and protease stability are often observed. Our understanding of the biosynthesis of these D-amino acid-containing peptides is still in its infancy. Nevertheless, the discovery of a novel peptide isomerase from the venom of the Agelenopsis aperta spider provides some important clues to explain the incorporation of single D-amino acid residues within a peptide chain. Given its high homology with other serine proteases, the isomerase may represent an opportune mutation in response to evolutionary pressures. Yet, is the isomerase a unique exception or simply the first in a class of enzymes of varying substrate specificity capable of synthesizing D-amino acid-containing peptides? To be sure, much more remains to be explored about the precise timing and mechanism of the isomerization process, in addition to obtaining further structural data on the enzyme itself. Therein lies the continuation of this fascinating story in enzyme biochemistry.

Allogeneic cancellous bone graft and a Burch-Schneider ring for acetabular reconstruction in revision hip arthroplasty.

BACKGROUND: There is an ever-increasing number of failed hip arthroplasties associated with massive deficiency of acetabular bone stock consisting of a segmental or cavitary defect. This study was undertaken to evaluate the long-term results after use of morselized cryopreserved allogeneic bone graft and an antiprotrusio cage to treat such a deficiency. METHODS: From January 1, 1988, to January 1, 1994, forty-one patients (forty-one hips) with an acetabular defect classified as type IIl or IV according to the American Academy of Orthopaedic Surgeons system were operated on with use of a Burch-Schneider ring and morselized cryopreserved allogeneic cancellous bone graft. Thirty-eight patients (thirty-eight hips) were available for clinical and radiographic follow-up examinations at an average of 7.3 years (range, 4.2 to 9.4 years) after surgery. RESULTS: All measured clinical parameters had improved significantly by the time of the follow-up examination (p < 0.0001). Radiographs confirmed that none of the thirty-eight hips had any measurable migration or displacement of the acetabular component and that osseous consolidation occurred only within the grafted area in all patients. CONCLUSION: Acetabular reconstruction with use of morselized cryopreserved allogeneic cancellous bone graft and the Burch-Schneider ring can be highly successful in managing massive acetabular deficiencies in revision hip arthroplasty.

Determination of split renal function from gamma camera renography: a study of three methods.

Three different methods for calculation of the split kidney function from gamma camera renography with 99Tcm-DTPA are surveyed in this study, the integral, the slope and the uptake index methods. The reproducibility in calculating the relative renal function was very good with all three methods (coefficient of variation 2-4%). Single kidney glomerular filtration rate (GFR) was assessed by the three methods and 51Cr-EDTA clearance prior to nephrectomy, giving the accuracy of each method. The slope and uptake index methods showed high accuracy (0.9-2.0 ml min-1), while it is significantly reduced with the integral method (4.6 ml min-1), compared to the postoperative 51Cr-EDTA clearance. The uptake index method enables calculation of a ratio between the kidneys (alpha/UI)SR, which relates each kidney's intrarenal blood volume (alpha) to its renal function (UI). This ratio was compared in a group consisting of 38 patients with kidney tumours and in a control group of 32 patients. It was rather constant in the control group but significantly higher and within a wider range in the group with renal tumours. These discrepancies may indicate an abnormal intrarenal blood volume. Furthermore, the correlation between results assessed by the three calculation methods in the control group was good, while the correlation in the group with renal tumours deteriorated.

Liver uptake function measured by IODIDA clearance rate in liver transplant patients and healthy volunteers.

Hepatobiliary scintigraphy with 99Tc(m)-diethyl-iodo-HIDA (IODIDA), an iminodiacetic acid derivative, is used to assess hepatocyte function and to visualize the hepatobiliary system. The aim of this study was to evaluate whether it is possible to describe liver function by calculating the clearance rate of IODIDA from the blood. Clearance rate was evaluated in 18 liver transplant patients (28 studies) and 11 healthy volunteers (11 studies). Two different clearance rates were calculated: the clearance of IODIDA from the blood due to liver uptake and the total clearance of IODIDA from the blood due to all possible routes of elimination. Both for the healthy controls and the liver transplant patients, there was an excellent correlation between these two methods (r = 0.92 and r = 0.93, respectively), indicating that the liver is the only essential pathway for elimination of IODIDA from the blood. The difference in clearance rate between healthy controls and liver transplant patients was highly significant (P < 0.01), corresponding to the clinical condition of the two groups. We conclude that the clearance rate of IODIDA, based on a simple measurement from the time-activity curve derived from a blood pool region of interest, is a reliable test of liver function.

Reliability of ACE inhibitor-enhanced 99Tcm-DTPA gamma camera renography in the detection of renovascular hypertension.

Twenty consecutive patients with renovascular hypertension, proven by cure or improvement of hypertension at 1-year follow-up after percutaneous transluminal angioplasty or surgical repair, were studied before intervention by means of gamma camera renography with 99Tcm-diethylenetriaminepentaacetic acid (99Tcm-DTPA) at baseline and after angiotensin-converting enzyme (ACE) inhibition. Sixteen patients underwent bilateral renal vein catheterization for measurement of renal vein renin release and extraction ratios of para-amino-hippurate (PAH) and 51Cr-EDTA before and after acute ACE inhibition. With the limit for a significant change in relative side distribution of 5% or more after ACE inhibition on gamma camera renography 13 patients responded (Group 1), while seven patients (Group 2) had unchanged side distribution. Glomerular filtration rate (GFR), measured with 99Tcm-DTPA, in the affected kidney decreased in Group 1 from 26 +/- 16 ml min-1 to 11 +/- 12 ml min1 (P < 0.0005), while GFR was unchanged in the affected kidney in Group 2, 26 +/- 13 ml min-1 versus 29 +/- 13 ml min-1. Extraction ratios of PAH and 51Cr-EDTA for the affected kidney in Group 1 decreased from 80 +/- 18 to 73 +/- 21% (P < 0.05) and from 16 +/- 5 to 7 +/- 5% (P < 0.005), respectively, while in Group 2 the PAH extraction ratio was not significantly changed, 86 +/- 5 versus 81 +/- 14%, but the 51Cr-EDTA extraction ratio for the affected kidney also decreased from 16 +/- 3 to 8 +/- 4% (P < 0.005). All patients had lateralization of renal vein renin to the affected kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

A Long Straight Stem with Distal Interlocking for Uncemented Stem Revision in THR.

Femoral revision in total hip replacement (THR) is often demanding due to severe bone defects of the proximal femur. The surgical technique must provide sufficient stability in the distal femur. However, long-term stability depends on preserving or even rebuilding proximal bone stock.

A modular system for cemented and cementless implantation of femoral stem prostheses.

A femoral stem [BiContact, Aesculap, Germany) has been developed which is suitable for both cemented and uncemented implantation. Thus a highly standardized procedure and a standard implant for any iritraoperative finding is available. While the cemented stems have a smooth surface, the cementless implants are proximally coated with a microporous titanium plasmaspray [Plasmapore]. The strategy based on the intraoperative choice of the surgeon to use either cemented or cementless implants after bone preparation turned out to be very successful in our institution. A consecutive series of 250 cases with cemented implantation and 250 cases with uncemented implantation was analyzed in a prospective follow-up study, Pollow-up time averaged 7 years for cemented and 6.5 years for uncemented THRs. The follow-up rate was 88.7% in cases treated with cemented stems and 93.1% in cases treated with uncemented stems. The rate of aseptic loosening was 1.2% for the cemented version and 0.4-% for the uncemented stem. Radiological loosening could be observed in another 1.2% of the cemented stems and was not to be found in the uncemented cases. Our data suggest an excellent midterm stability of both the cemented and the uncemented version of the BiContact hip system. The long-term results for both the cemented and uncemented prostheses of our series are still to be evaluated.

Changes of blood flow velocity indicating mechanical compression of the vertebral arteries during rotation of the head in the normal human measured with transcranial Doppler sonography.

The dynamical changes of blood flow velocity of the intracranial vertebral arteries (VA's) and proximal basilar artery (BA) provoked by rotation of the head in normal volunteers were measured using pulsed-wave transcranial Doppler sonography (TCD). In another group both VA's were examined simultaneously with 2-channel TCD. Blood flow velocities diminished compared to the neutral position in all vessels, independently of the side. Total obstruction of the flow was not observed. Our findings reveal a definitive decrease of blood flow velocity at the vertebrobasilar artery system provoked by rotation of the head in normal humans. This physiological phenomenon is suggested to have an impact on the cerebral blood flow in patients with impaired autoregulation of the cerebral vessels, low volume flow reserve in the contralateral VA or insufficient collateral channels because of normal anatomical variation, especially those patients under general anesthesia or comatose.

[Renal artery stenosis--an underestimated cause of hypertension and renal failure?]. / Njurartärstenos--underskattad orsak till hypertoni och njursvikt?

Although renovascular hypertension is associated with substantial cardiovascular morbidity, ultimately it is a curable disease. Early identification and appropriate treatment of renovascular hypertension may save years of antihypertensive therapy, reduce the morbidity associated with long-standing hypertension, and help to minimise the risk of renal failure. However, the main problem is to identify patients with renovascular disease suitable for treatment. This requires alertness in the clinician, and renographic screening of renal function or duplex-ultrasound scanning of renovascular circulation to augment the yield of angiographic procedures. The predominant treatment of renovascular disease today is percutaneous transluminal angioplasty, which can be used as a repeat procedure or in combination with endoluminal stenting of the stenotic renal artery.