Properties of the catalytic center of a secretory 28kDa protein (1-cys peroxiredoxin) from rat olfactory epithelium

BACKGROUND: Percutaneous mitral valvuloplasty with the Inoue balloon is conventionally performed with double vascular access: arterial and venous. However, in patients with a good echogenic window it may be performed with venous access only and the procedure monitored by 2D-echocardiography and colour flow mapping. This should result in early ambulation and hospital discharge with reduced arterial complications. AIMS: To compare retrospectively the immediate results of percutaneous mitral valvuloplasty with the Inoue balloon in two groups of patients: Group I: venous access only (no arterial access, n = 102) and Group II: conventional double vascular access (arterial and venous access, n = 275). METHODS AND RESULTS: The baseline characteristics of the two groups were comparable for age, sex, clinical, echocardiographic, radiological and haemodynamic variables. The mitral valve area (Group I: 1.1 +/- 0.3 to 1.85 +/- 0.5 cm2 vs Group II: 1.05 +/- 0.2 to 1.85 +/- 0.5 cm2, P = ns) and transmitral gradient (Group I: 11 +/- 4 to 4.7 +/- 2 mmHg vs Group II: 12 +/- 4 to 4.8 +/- 2 mmHg, P = ns) before and after mitral valvuloplasty were not statistically different. A good immediate result, defined as mitral valve area > 1.5 cm2 and mean mitral gradient < 5 mmHg with mitral regurgitation < or = 2+ at the end of the procedure, was observed in 77% of the cases in the venous-only group and 79% in the double access group (P = ns). The incidence of severe mitral regurgitation (Grade III or IV) was not statistically significant. Procedural duration (71 +/- 24 min vs 109 +/- 26 min, P < 0.01), fluoroscopic time (12.5 +/- 5.5 min vs 18.5 +/- 6 min, P < 0.01) and hospital stay (2.8 +/- 1.5 days vs 4.8 +/- 2.6 days, P < 0.001) were significantly shorter in the venous-only group than in the conventional Inoue series. CONCLUSION: Single venous access balloon mitral valvuloplasty is as equally safe and effective as double vascular access. The additional advantages of single venous access are shorter procedural duration, fluoroscopic time and hospital stay. We recommend that it be performed by an experienced operator (minimum of 100 trans-septal punctures) in patients without major thoracic deformity and a good echogenic window.     

Hepatic imaging. An overview

Chronic food restriction reduces blood pressure (BP) and sympathetic support of BP in aortic coarctation hypertension. The purpose of this study was to test the hypothesis that chronic food restriction would reduce sympathetic support of BP mediated by the paraventricular hypothalamic nuclei (PVN). Hypertension was induced in male Sprague-Dawley rats (n=40) by suprarenal aortic coarctation. Rats were assigned to either an ad libitum fed (AL) group or a food restricted (FR) group that received 60% of the food consumed by AL for 3 weeks. One week prior to data collection, catheters were implanted in the left carotid artery and right jugular vein. BP was measured for 2 days prior to, and 7 days after rats in AL and FR groups received either bilateral electrolytic lesions of the PVN (PVNx) or sham lesions (SHAM). Prior to either PVNx or SHAM, FR rats had significantly lower BP (AL=152+/-5; FR=113+/-2 mmHg), less of a depressor response to ganglionic blockade (AL=-58+/-4; FR=-35+/-2 mmHg), and lower plasma norepinephrine levels (AL=758+/-71; FR=380+/-23 pg/ml) compared to AL. PVNx reduced BP in both AL and FR rats (AL-PVNx=105+/-6 mmHg, FR-PVNx=101+/-3 mmHg). PVNx also lowered the depressor response to ganglionic blockade (AL-PVNx=-28+/-5 mmHg, FR-PVNx=-29+/-4 mmHg) and plasma norepinephrine levels (AL-PVNx=372+/-74 pg/ml, FR-PVNx=248+/-31 pg/ml). FR decreased the magnitude of the reductions in resting BP and in sympathetic activity in response to PVNx. These results indicate that intact PVN are required for maintenance of aortic coarctation hypertension, and implicate the PVN as a site involved in BP reductions produced by chronic food restriction.     

Antihypertensive effects of food-intake restriction in aortic coarctation hypertension

OBJECTIVE: To test the hypothesis that reductions in mean arterial pressure (MAP) induced by food-intake restriction in aortic coarctation hypertension are the result of a reduction of the sympathetic support of the MAP. We also wanted to determine whether the baroreflex control of the heart rate, and alpha- and beta-adrenergic responsivenesses were influenced by chronic food-intake restriction. METHODS: Four days after aortic coarctation, female Sprague-Dawley rats were assigned to a group that had access ad libitum to food (CON; n = 19) or to a food-intake-restricted group (FRG; n = 17) that was allowed 60% of the CON group's food intake per rat. After 3 weeks, carotid and jugular catheters were implanted for measurement of the MAP and infusion of drugs into conscious rats. The sympathetic contribution to the blood pressure was assessed by measuring the depressor response to ganglionic blockade by hexamethonium plus atropine (30.0 and 0.1 mg/kg intravenously). The baroreflex control of the heart rate was assessed by administering alternating bolus doses of phenylephrine and nitroprusside. The alpha-adrenergic sensitivity was assessed by measuring the response of the MAP to phenylephrine in areflexive rats (after ganglionic blockade), and the beta-adrenergic sensitivity was assessed by measuring the responses of the MAP and heart rate to isoproterenol administration both in reflexive and in areflexive rats. RESULTS: Four days after catheterization, both the MAP (CON 150 +/- 5 mmHg, FRG 116 +/- 4 mmHg) and the heart rate (CON 414 +/- 8 beats/min, FRG 365 +/- 11 beats/min) were significantly lower in rats of the FRG. That the sympathetic support of the MAP had diminished in FRG rats was evidenced by an attenuated depressor response to ganglionic blockade (40 +/- 3 versus 65 +/- 3 mmHg). FRG rats exhibited significantly greater reflex bradycardia in response to phenylephrine (slope -1.44+/- 0.07 versus -0.54 +/- 0.05 beats/min per mmHg), whereas their reflex tachycardia was not altered (slope -1.58 +/- 0.08 versus -1.53 +/- 0.13 beats/min per mmHg). FRG rats also displayed blunted responses of the heart rate and MAP to isoproterenol administration. CONCLUSION: Food-intake restriction attenuates the rise in MAP which occurs after aortic coarctation significantly. The antihypertensive effect of food-intake restriction may be mediated via a reduction in sympathetic tone.     

Early clinical and hemodynamic evaluation of the aortic intact porcine bioprosthesis

Between October 1990 and June 1992, 89 patients underwent aortic valve replacement using the Intact porcine bioprosthesis. Their mean age (+/- SD) was 74.6 +/- 7.8 years (range 48 to 92). Seventy-five percent were in NYHA Class III-IV, 79 (89%) had AS or AS/AI, 10 (11%) had had previous cardiac surgery and 25 (32%) had an EF < 0.50. Associated procedures included CABG 45 (51%), septal myectomy 13 (15%), annular enlargement eight (9%), LV aneurysmectomy one, ascending aortic replacement one, and arch replacement one. Hospital mortality was four (4.5%). Hemodynamics were assessed with 2D echo with Doppler at seven days, six weeks and 12 months, and compared with 130 standard Carpentier-Edwards (C-E) porcine bioprostheses. At follow up, two patients have 2/4 perivalvular AI. The transvalvular gradients for the Intact valve were as follows: 21 mm-16.9 +/- 7.4 mmHg; 23 mm-18.9 +/- 6.2 mmHg; 25 mm-17.1 +/- 5.4 mmHg; 27 mm-15.0 +/- 3.7 mmHg; and 29 mm-15.0 +/- 2.1 mmHg. When compared to the standard Carpentier-Edwards porcine bioprostheses, the 21 mm Intact valve had the same gradient as the C-E prosthesis. However, the transvalvular gradients were slightly higher for the Intact valve for sizes 23-29 mm when compared to the corresponding C-E valve. The effective orifice area and effective orifice area index was no different between the two valves. Satisfactory hemodynamics are seen in the smaller prostheses when valves are matched for BSA and when aortic annular enlargement is performed when necessary.     

Evaluation of HBsAg carrier rate in acute viral hepatitis and high risk individuals using RPHA and ELISA

INTRODUCTION: Balloon valvuloplasty in neonates and small infants with critical aortic stenosis is a palliative procedure. The present report describes the results of the technique in our center. METHODS: From April 1993 to March 1995, six consecutive patients with critical aortic valve stenosis underwent catheter-balloon valvuloplasty. Their ages ranged from 2 to 120 days old (45.5 +/- 47.5 days). Four patients had associated lesions: 2 had coarctation of the aorta, 1 had ischemic dilated cardiomyopathy and 1 had endocardial fibroelastosis. Percutaneous femoral artery access was used in four cases and axillary artery dissection in two. RESULTS: The balloon-annulus diameter ratio was 0.92 +/- 0.12. The peak systolic ejection gradient decreased from 66.1 +/- 26.4 to 38 +/- 15.7 mmHg (p < 0.05) and the left ventricle systolic pressure decreased from 136.3 +/- 26.8 to 115 +/- 22.5 mmHg (p < 0.05). There were no mortalities related to the procedure. Both patients who had aortic coarctation developed aortic regurgitation and died after repairing of the coarctation. The patient with endocardial fibroelastosis died during an attempt to perform the Norwood operation (Stage I) and the other patient with ischemic dilated cardiomyopathy survived after cardiac transplantation. The remaining two patients with isolated aortic valve stenosis are currently asymptomatic. CONCLUSIONS: Catheter-balloon valvuloplasty is an effective procedure in the initial treatment of critical aortic stenosis and may be life saving.     

Doppler haemodynamic assessment of clinically and echocardiographically normal mitral and aortic Allcarbon valve prostheses. Valve Prostheses Ligurian Cooperative Doppler Study

Doppler echocardiographic characteristics of normally functioning Allcarbon prostheses were studied in 149 consecutive patients with 157 valves in the mitral (n = 73) and aortic (n = 84) positions whose function was considered normal by clinical and echocardiographic evaluation. In the mitral position, the mean gradient and the effective mitral orifice area were not significantly different in either the 25-mm or the 31-mm size valves (from 5 +/- 1 to 4 +/- 1 mmHg and from 2.2 +/- 0.6 to 2.8 +/- 0.9 cm2, respectively; P = ns for both). Conversely, peak gradient was significantly and inversely correlated to actual orifice area (r = -0.70; P < 0.0006), decreasing from 15 +/- 3 mmHg in the 25-mm size valve to 9 +/- 1 mmHg in the 31-mm size. In the aortic position, the mean gradient was 29 +/- 8 mmHg in the 19-mm size valve; it decreased to 8 +/- 2 mmHg in the 29-mm size. Effective prosthetic aortic valve area, calculated using the continuity equation, ranged between 0.9 +/- 0.1 cm2 for the 19-mm size valve to 4.1 +/- 0.7 cm2 for the 29-mm size. By analysis of variance, effective prosthetic aortic valve area differentiated various valve sizes (F = 25.3; P < 0.0001) better than peak (F = 5.34; P = 0.012) or mean (F = 4.34; P = 0.0052) gradients alone, and it correlated better with actual orifice area (r = 0.89, r = -0.70 and r = -0.65, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of blood flow rates and hydraulic resistance between the Mahurkar catheter, the Tesio twin catheter, and the Ash Split Cath

The Ash Split Cath (Medcomp, Harleysville, PA) is a recently introduced dual lumen permanent catheter designed to be placed through the internal jugular vein into the superior vena cava by single venipuncture technique. The transcutaneous portion is a 14 French cylindrically shaped catheter with D-shaped lumens and a Dacron (DuPont, Wilmington, DE) cuff. At the entrance to the jugular vein, the catheter splits into two separate D-shaped limbs that then merge into multiholed cylindrical tips in the vena cava. Split Caths (n = 10) have been placed in patients with end-stage renal disease and used for outpatient dialysis for approximately 2 months. Flow rates and hydraulic resistance have been compared with Mahurkar (Bard, Salt Lake City, UT) (n = 22) and Tesio (Medcomp) (n = 17) catheters in the same unit. Average blood flow rates (Qb) were 295 +/- 42 (SD) for Ash Split Caths vs 279 +/- 38 and 300 +/- 39 ml3/min for Mahurkar and Tesio catheters, respectively, and hydraulic resistances were 0.44 +/- 0.17, 0.52 +/- 0.15, and 0.56 +/- 0.11 mmHg/ml/min, respectively (not significant). No Split Caths have been removed for bleeding or flow complications. The Split Cath provides the simplicity of placement and removal of a single-bodied catheter with flow advantages of independent, cylindrical, multiholed tips.     

Malnutrition in geriatric patients: a neglected problem?

PURPOSE: The authors report their experience with the translumbar inferior vena cava (IVC) approach for central venous access during a 6-year period at three teaching hospital sites. PATIENTS AND METHODS: Twenty-nine percutaneous IVC central venous access catheters were inserted in 22 patients during a 6-year period in the radiology departments of three teaching hospital sites. All patients had undergone unsuccessful attempts at conventional central venous access. Information was gathered by retrospective radiologic and hospital chart review. RESULTS: All attempted placements were successful. Catheters were in place for a total of 3,510 catheter days. The average length of catheter placement was 121 days (range, 14-536 days). Life-table analysis predicted catheter function rates of 55% and 29% at 6 and 12 months, respectively. Three procedure-related complications occurred. A lower pole branch of the right renal artery was inadvertently entered with a 22-gauge needle during attempted IVC puncture in one patient without clinical sequelae. A second patient developed a small groin hematoma at the femoral venous puncture site, which resolved spontaneously. A third patient developed a moderate retroperitoneal hematoma, which resolved without specific intervention. The sepsis rate was 2.8 infections per 1,000 catheter days with an average time to infection of 127 days (range, 10-536 days). CONCLUSION: In the authors' experience of 29 translumbar central venous catheter insertions, all attempts were successful. Percutaneous central venous access via the IVC is a safe and effective option for patients in whom more conventional access is not possible.     

Applications and outcome of hemodialysis in cats: a review of 29 cases

Hemodialysis (HD) has been used in the management of renal failure in dogs, but its feasibility has not been reported for uremic cats. Therefore, we investigated the technical possibility, efficacy, and complications of intermittent HD in cats with severe uremia. A total of 160 HD treatments were performed on 29 cats with acute renal failure (ARF) (n = 15), chronic renal failure (CRF) (n = 6), or acute on CRF (n = 8) between November 1993 and June 1996. Hemodialysis treatments were performed with transcutaneous dialysis catheters using a bicarbonate-based delivery system, sodium modeling, and volumetric-controlled ultrafiltration. Presenting serum chemistries (mean +/- SD) for all cats were creatinine, 16.4 +/- 7.5 mg/dL; blood urea nitrogen (BUN), 229 +/- 87 mg/dL; phosphate, 15.4 +/- 5.4 mg/dL; potassium, 6.0 +/- 1.6 mEq/L; and HCO3-, 16.0 +/- 4.4 mEq/L. For intensive HD treatments, pre-HD versus post-HD creatinine changed from 10.3 +/- 4.4 to 1.6 +/- 0.9 mg/dL and BUN from 105 +/- 33 to 8 +/- 10 mg/dL. One or more adverse events occurred during 111 (69%) treatments. Dialysis-related events included hypotension, dialysis dysequilibrium, clotting, and bleeding. Nine of 15 (60%) cats with ARF and 1 cat with CRF recovered sufficiently to survive without ongoing need for HD. For the remaining cats, the proximate causes of death were dialysis related in 9 cats, uremia related in 6 cats, and iatrogenic or unknown in 4 cats. Hemodialysis is technically feasible and effectively controls the biochemical disturbances of uremic cats. It is especially valuable for the management of severe ARF, permitting recovery in a large number of cats refractory to conventional therapy. Technical complications and chronic debility, however, may limit its usefulness for cats with advanced CRF.     

A subconjunctival degradable implant for cyclosporine delivery in corneal transplant therapy

The effect of local cyclosporine therapy upon corneal transplant survival was investigated. A high risk rabbit model with vascularized corneas was used to assess the efficacy of subconjunctivally implanted degradable devices for cyclosporine therapy. Animals were divided into four groups, receiving either no therapy, a placebo PLGA device, or drug containing devices implanted either at the time of transplantation or two weeks previous. The mean survival times of animals in the control and placebo groups were statistically equivalent (21 +/- 4 days vs 18 +/- 4 days). Devices containing CsA improved the survival time of grafts. Predosing the animals with CsA improved the survival time to 28 +/- 7 days, and CsA devices implanted at the time of transplantation increased the survival time to 35 +/- 7 days. The improvement in survival times was consistent with the in vitro drug release profiles. No systemic CsA was detected, suggesting that the effect may have been local. Histological assessment indicated that devices were well tolerated.     

Central venous catheter failure is induced by injury and can be prevented by stabilizing the catheter tip

PURPOSE: Thrombosis associated with central venous catheters is a significant cause of device failure, morbidity, and loss of access sites. We hypothesized that central vein thrombosis is caused by catheter injury to the vein wall and that it can be reduced by stabilizing the catheter tip. To test these hypotheses, we studied central vein catheters in a porcine model. Test catheters had a silicone-encased stainless steel loop at the indwelling end that contacted the vein wall and stabilized the catheter tip in the center of the vessel. METHODS: Sealed silicon elastic (Silastic) catheters (3.2 mm outer diameter) with and without a stabilizing loop were inserted via the external jugular vein into the superior vena cava just above the right atrium. Animals were killed at 1, 2, 4, and 8 weeks, and the vena cava was inspected for the presence of thrombus and entrapment of the catheter tip. RESULTS: In control animals mural thrombus developed at the site of the catheter tip. This thrombus organized by invasion of macrophages and smooth muscle cells, eventually forming a lesion similar to intimal hyperplasia. Lesion cross-sectional area was significantly smaller in animals with loop catheters than in control animals at 2 weeks (1.2 +/- 1.3 vs 34.5 +/- 23.9 mm2; p = 0.05) and 4 weeks (2.8 +/- 0.3 vs 13.9 +/- 5.8 mm2; p < 0.05). By 8 weeks the vena cava was nearly occluded in most animals and the catheter tip was entrapped in this lesion in all cases. Test catheters eliminated the injury process for up to 8 weeks (p < 0.01, chi2 control vs loop catheter entrapment). Very little injury response was found where the loop contacted the vein wall, and the catheter tip was free of thrombus in all cases. CONCLUSIONS: Mural thrombosis at the tip of indwelling central catheters is caused by chronic mechanical venous wall injury. Vessel injury and the resulting thrombosis can be prevented by a catheter modification that stabilizes the tip. Such a catheter may significantly reduce catheter malfunction and morbidity associated with these devices.     

Use of the Nippon-Zeon pneumatic ventricular assist device as a bridge to cardiac transplantation

The Nippon-Zeon (NZ) ventricular assist device is a sac type, air driven, heterotopic, external pump. Its performance has been evaluated in Japan as a bridge to myocardial recovery. Few data are available on the device as a bridge to heart transplantation. Since 1991, 10 patients (9 men) were bridged to heart transplantation with NZ, all in biventricular support. The mean age was 39 +/- 13 years (range, 21-60 years), mean body weight was 75 +/- 13 kg (range, 51-95 kg). Five patients had a dilated cardiopathy, and five were ischemic (three acute myocardial infarctions). Despite maximal inotropic support, including enoximone in seven, epinephrine in three, and intraaortic balloon pumping in one, eight patients were anuric, three were in acute hepatic failure, and three were intubated. Preoperative hemodynamic and biologic values were: cardiac index, 1.57 +/- 0.4 l/min/m2; pulmonary capillary wedge pressure, 34 +/- 5 mmHg; creatinine, 200 +/- 80 mumol/l; blood urea nitrogen, 17.5 +/- 8 mmol/l; total bilirubin 36 +/- 6 mumol/l; aspartate aminotransferase, 1,000 +/- 2,000 IU/l. In all patients, a biventricular assist device was implanted without the use of cardiopulmonary bypass. Improvement occurred immediately in all but one. Mean left ventricular flow was 4.5 +/- 0.8 l/min. Anticoagulation was maintained with intravenous heparin. Recently for bleeding was required in one case (10%), and two patients had positive blood cultures that were successfully treated. There was no mechanical failure. Hemolysis was not significant (lactate dehydrogenase, 378 +/- 50 IU/l; plasma-free hemoglobin below 10 mg/dl). Each device was free of thrombi and deposits at time of explantation. One patient died while on assist. Nine patients (90%) were transplanted after 11 +/- 8 days (range, 1-32 days). Three died early after transplantation, one of graft failure, two of sepsis. Six patients (66%) could be discharged. The follow-up ranges from 7 to 28 months. NZ is a simple, reliable, pneumatic device driven by a light, silent console; it can be rapidly implanted without cardiopulmonary bypass in patients in desperate condition who are awaiting cardiac transplantation. The difficulty of patient rehabilitation while using this device should limit the duration of support to weeks to allow the patient to be in optimal condition for heart transplantation.     

Balloon pulmonary valvuloplasty in children, one year follow-up experience at Ramathibodi Hospital

Balloon valvuloplasty has become the treatment of choice in pulmonary valvular stenosis. The objective of this report is to review the experience of this procedure in children at the Department of Pediatrics, Ramathibodi Hospital in the past 4 years (1991-1994) with at least one year follow-up. During the study period, 19 children aged 2.1-14.3 years (mean 5.11 years) with the diagnosis of pulmonary valvular stenosis had successful pulmonary balloon valvuloplasty at this institution. The immediate peak systolic pressure gradient across the pulmonary valve by cardiac catheterization decreased from 92.05 +/- 46.92 to 34.26 +/- 25.30 mmHg, by Doppler from 78.58 +/- 26.55 to 34.83 +/- 15.60 mmHg. Peak pressure gradient across the pulmonary valve by Doppler of the last examinations, one to 4 years after the procedure (mean 1.9 years), was 23.05 +/- 9.40 mmHg in 17 patients. The mean ratio of balloon size and pulmonary valve ring was 1.06. One patient still has a residual gradient of 54 mmHg and two were lost to follow-up. No serious complication was encountered during the procedures. CONCLUSION: Balloon pulmonary valvuloplasty is effective in the management of children with valvular pulmonary stenosis. The intermediate term result is excellent.     

Treatment of end-stage renal failure after heart transplantation

BACKGROUND: Five to 10% of heart-transplant recipients develop end-stage renal failure (ESRF). Little is known about the outcome of these patients under renal replacement therapy. METHODS: We conducted a retrospective study in 16 men (mean age 52.8+/-7.4 years at heart transplantation) who developed ESRF 5.3+/-2.1 years later. Results. Haemodialysis (HD) was the first-line treatment (mean Kt/V 1.35+/-0.4). Vascular access was unsuccessful in six patients (37.5%) due to peripheral arteriopathy and they were treated with tunnelled catheters for an average 15 months without bacterial infection. Mean weight was 68.4+/-10 kg at onset of HD and 61.7+/-9 kg one month later. Despite this reduction in extracellular overload, one antihypertensive drug was required in 75% of patients and two drugs in 12.5%. One patient tolerated automated peritoneal dialysis (PD) for 16 months (weekly Kt/V 2.1) despite persistent anuria. Renal transplantation (RT) was contraindicated in eight patients because of aortoiliac arteriopathy (n=5), poor general status (n=2), or ischaemic heart disease (n=1). RT was performed in eight patients with no acute episode of heart or renal graft rejection. There were no serious infectious complications. Three months after RT, mean serum creatinine was 115 micromol/l. One patient developed post-transplant lymphoproliferative disorder 3.5 months after RT and was successfully treated with transplant nephrectomy. Sudden death occurred in two patients 18 and 33 months after RT. Overall patient survival was 100, 78, and 59%, 1, 2 and 3 years after HD onset respectively. Using a time-dependent variable, the Cox model analysis demonstrated that heart-transplant recipients with ESRF have a relative risk of death 3.2 times higher than those without ESRF (95% CI = 1.3-7.8). CONCLUSIONS: HD, PD, and RT can be useful for the treatment of ESRF after heart transplantation. After initiating HD, patient survival is nearly the same as that reported in patients in Europe undergoing HD for other causes. But ESRF seems to reduce life expectancy in heart-transplant recipients.     

Correlates of lens thickness: the Beaver Dam Eye Study

Stenosis of the subclavian vein (SVS) after cannulation occurs in 15 to 50% of chronic hemodialysis patients, and impedes the placement of an arteriovenous fistula in the ipsilateral arm. Its natural history and pathogenic mechanisms are not well established. This study examined 42 consecutive chronic renal failure patients (28 men and 14 women; 46+/-19 yr) in whom subclavian catheters had been placed as the initial vascular access for hemodialysis. All patients underwent sequential venography studies: at baseline (24 to 48 h after removal of the catheter) and 1, 3, and 6 mo thereafter. Venograms were considered abnormal when there was evidence of unequivocal strictures (more than 30% narrowing), with or without collateral circulation. At baseline, 52.4% (n=22) of patients showed stenotic vein lesions (n=19) or total thrombosis (n=3), and identical lesions were also observed after 1 mo. Surprisingly, 10 of 22 patients with initial SVS (45.4%) showed spontaneous recanalization of venous lesions in the venographies performed 3 mo after removal. The patients with normal baseline venograms (n=20) showed no change during follow-up. Patients with definitive stenosis at 6 mo (n=12) had a higher number of inserted catheters (1.58+/-0.6 versus 1.2+/-0.48; P < 0.05), longer time in place (49.08+/-32.2 versus 29.03+/-26.6 d; P < 0.05), and higher number of dialysis sessions (21+/-13.8 versus 12.4+/-11.4; P < 0.05) than those without SVS or with spontaneous recanalization of venous lesions during follow-up. Furthermore, a higher number of catheter-related infections were observed in patients with definitive SVS (66.6% versus 33.3%; P < 0.05). In summary, SVS is observed in more than half of patients 24 to 48 h after catheter removal and 1 mo later. Even when recanalization occurs in many cases, a definitive stenosis is seen in 28% of patients by the third month. Thus, the creation of an ipsilateral vascular access is possible provided that venography is normal at this time. Finally, mechanical factors and catheter-related infections are the major risk factors for the development of late SVS.     

Comparison of toxicity induced by HT-2 toxin on human and rat granulo-monocytic progenitors with an in vitro model

Catheter-associated bloodstream infections remain an important cause of nosocomial infection, with an estimated 50,000-100,000 cases occurring each year in the United States. Central venous catheters are believed to be responsible for 90% of such infections. The cumulative risk of acquiring a catheter-related bloodstream infection has ranged between 1 and 10% for central venous catheters in general and 6% for total parenteral nutrition catheters. The skin is the most common source of organisms causing catheter-related infections. Recent prospective studies have shown that the incidence density per catheter day does not increase with duration of catheterization and that routine changes, either over a guidewire or by new site puncture, do not appear to lower the risk of infection. Diagnosis of infection can be difficult in intensive care patients but is usually easier in less ill patients with a central venous catheter. Quantitative or semiquantitative laboratory techniques can be used to confirm the diagnosis in the appropriate clinical setting. A variety of preventive measures have been shown to minimize the risk of development of catheter-related bloodstream infection, including use of maximal aseptic technique for insertion, use of special teams for care of the catheter, limiting manipulation of the catheter, use of povidone-iodine ointment and cotton gauze dressings for recently inserted catheters, a silver-impregnated collagen cuff and antiseptic-impregnated catheters.     

Percutaneous mechanical mitral commissurotomy with a newly designed metallic valvulotome: immediate results of the initial experience in 153 patients

BACKGROUND: Percutaneous balloon valvotomy has become a common treatment of mitral stenosis, but the cost of the procedure remains a limitation in countries with restricted financial resources, leading to a frequent reuse of the disposable catheters. To overcome this limitation, a reusable metallic valvotomy device has been developed with the goals of both improving the mitral valvotomy results and decreasing the cost of the procedure. METHODS AND RESULTS: The device consists of a detachable metallic cylinder with 2 articulated bars screwed onto the distal end of a disposable catheter whose proximal end is connected to an activating pliers. By the transseptal route, the device is advanced across the valve over a traction guidewire. Squeezing the pliers opens the bars up to a maximum extent of 40 mm. The clinical experience consisted of 153 patients with a broad spectrum of mitral valve deformities. The procedure was successful in 92% of cases and resulted in a significant increase in mitral valve area, from 0.95+/-0.2 to 2. 16+/-0.4 cm2. No increase in mitral regurgitation was noted in 80% of cases. Bilateral splitting of the commissures was observed in 87%. Complications were 2 cases of severe mitral regurgitation (1 requiring surgery), 1 pericardial tamponade, and 1 transient cerebrovascular embolic event. In this series, the maximum number of consecutive patients treated with the same device was 35. CONCLUSIONS: The results obtained with this new device are encouraging and at least comparable to those of current balloon techniques. Multiple uses after sterilization should markedly decrease the procedural cost, a major advantage in countries with limited resources and high incidence of mitral stenosis.     

The loss of pacing-induced preconditioning in atherosclerotic rabbits: role of hypercholesterolaemia

A brief rapid pacing has been shown to protect rabbit heart against global myocardial ischaemia induced by subsequent longer pacing. We studied whether pacing-induced preconditioning was reproducible in experimental hypercholesterolaemia. In conscious rabbits with an implanted right ventricular electrode and left ventricular polyethylene catheters, pacing of 500 bpm over 20 min induced an intracavitary ST-segment elevation of 3.2 +/- 0.41 mV, shortened ventricular effective refractory period and increased left ventricular end-diastolic pressure from prepacing 105 +/- 3.9 ms and 4.0 +/- 0.93 mmHg to post-pacing 62 +/- 6.4 ms and 27.9 +/- 7.2 mmHg, respectively. A 10-min preconditioning pacing followed by a 5-min interval markedly attenuated these test pacing-induced ischaemic changes. Rabbits were fed a cholesterol-enriched diet over 4, 8 and 12 weeks, responded to a 5- or 10-min pacing with ischaemic changes of the same degree as did controls to a 10- or 20-min pacing, respectively. A 4-week diet elevated total serum cholesterol from 1.7 +/- 0.4 to 24.1 +/- 2.9 mmol/l without apparent atherosclerotic lesions in the thoracic aorta assessed by Oil-Red O staining and planimetry, but it abolished protection induced by a 5-min preconditioning pacing. A 12-week diet increased serum cholesterol and lesion surface area to 26.9 +/- 3.2 mmol/l and 89.6 +/- 6.4%, respectively, and continued to block preconditioning. When these animals were refed normal chow over additional 6 weeks, serum cholesterol level dropped to 2.6 +/- 0.80 mmol/l with no change in atherosclerotic lesions, the preconditioning effect, however, recovered. We conclude that hypercholesterolaemia blocks preconditioning irrespective of the development of atherosclerosis.     

Surgical treatment of fixed subvalvular aortic stenosis. Immediate and long-term hemodynamic results

Forty patients operated on for fixed subvalvular aortic stenosis underwent cardiac catheterization preoperatively, immediately after coming off cardiopulmonary bypass and at long-term (1 to 14 years later, average 7 +/- 3.9 years). The age range was 3 to 50 years (average 15 +/- 12 years) with 27 (68%) aged under 18 years. Twenty-seven patients were male. The stenosis was the thin membranous type in 29, the fibromuscular collar type in 5, the tunnel type in 5 others and related to supernumerary mitral tissue in the remaining patient. Significant other pathology was associated in 13 cases. In addition to excision of the membrane or the fibromuscular ring, the surgeons performed myotomy in 6 cases, myomectomy in 12 cases, large resection of muscular and fibrous tissue in tunnels, and aortic valve replacement in 3 cases. There was no operative fatality. Permanent cardiac pacing was required in 1 patient for complete atrioventricular block. The peak systolic pressure gradient fell from 87 +/- 32 to 31 +/- 10 mmHg (p < 0.0001) at the immediate control: it remained > 30 and even 50 mmHg in 3 patients (7.5%), 2 of whom had tunnel types and the other the supernumerary mitral tissue. The gradient increased in the long-term to 42 +/- 11 mmHg, 1 patient with a membrane developed a gradient of 40 mmHg and 4 others (10%) developed a gradient > 50 mmHg (3 tunnels and 1 membrane). The 5 patients with tunnel types either had a residual stenosis or restenosis and underwent aorto-ventriculoplasty by Konno's procedure 1 to 8 years later. This operation should be the procedure of first intention, even in small children: the large resection is only acceptable when it cannot be performed or when aortic ring hypoplasia is mild. There is no residual stenosis and restenosis is rare (2.5%) in the membranous and fibromuscular types, probably because of the widespread use of myotomy and myomectomy. In the absence of severe associated malformations, surgery in only justified when peak systolic pressure gradients are > or = 50 mmHg.     

Evaluation of dual-tip micromanometers during 21-day implantation in goats

Investigative research efforts using a cardiovascular model required the determination of central circulatory haemodynamic and arterial system parameters for the evaluation of cardiovascular performance. These calculations required continuous beat-to-beat measurement of pressure within the four chambers of the heart and great vessels. Sensitivity and offset drift, longevity, and sources of error for eight 3F dual-tipped micromanometers were determined during 21 days of implantation in goats. Subjects were instrumented with pairs of chronically implanted fluid-filled access catheters in the left and right ventricles, through which dual-tipped (test) micromanometers were chronically inserted and single-tip (standard) micromanometers were acutely inserted. Acutely inserted sensors were calibrated daily and measured pressures were compared in vivo to the chronically inserted sensors. Comparison of the pre- and post-gain calibration of the chronically inserted sensors showed a mean sensitivity drift of 1.0 +/- 0.4% (99% confidence, n = 9 sensors) and mean offset drift of 5.0 +/- 1.5 mmHg (99% confidence, n = 9 sensors). Potential sources of error for these drifts were identified, and included measurement system inaccuracies, temperature drift, hydrostatic column gradients, and dynamic pressure changes. Based upon these findings, we determined that these micromanometers may be chronically inserted in high-pressure chambers for up to 17 days with an acceptable error, but should be limited to acute (hours) insertions in low-pressure applications.