Prolonged elevation of plasma free fatty acids impairs pancreatic beta-cell function in obese nondiabetic humans but not in individuals with type 2 diabetes

Our recent in vivo observations in healthy nonobese humans have demonstrated that prolonged elevation of plasma free fatty acids (FFAs) results in diminished glucose-stimulated insulin secretion (GSIS) when the FFA-mediated decrease in insulin sensitivity is taken into account. In the present study, we investigated whether obese individuals and patients with type 2 diabetes are more sensitive than healthy control subjects to the inhibitory effect of prolonged elevation of plasma FFAs on GSIS. In seven patients with type 2 diabetes and seven healthy nondiabetic obese individuals, we assessed GSIS with a programmed graded intravenous glucose infusion on two occasions, 6-8 weeks apart, with and without a prior 48-h infusion of heparin and Intralipid, which was designed to raise plasma FFA concentration approximately twofold over basal. The nondiabetic obese subjects had a significant 21% decrease in GSIS (P = 0.0008) with the heparin and Intralipid infusion, associated with a decrease in whole body insulin clearance. The impairment in GSIS was evident at low (<11 mmol/l) but not at higher plasma glucose concentrations. In contrast, the patients with type 2 diabetes had a slight increase in GSIS (P = 0.027) and no change in insulin clearance, although there was marked interindividual variability in response. Plasma proinsulin concentrations measured in a subset of subjects were not altered in either group by the infusion of heparin and Intralipid. In summary, 1) obese nondiabetic individuals are susceptible to a desensitization of GSIS with heparin and Intralipid infusion, and 2) patients with type 2 diabetes do not demonstrate such susceptibility when FFAs are elevated approximately twofold above basal with heparin and Intralipid. Our results suggest that FFAs could play an important role in the development of beta-cell failure in obese individuals who are at risk for developing type 2 diabetes. They do not, however, seem to further deteriorate the beta-cell function of patients who already have established type 2 diabetes and may even result in a slight increase in GSIS in this latter group.

Tolerance induced without immunosuppression in a T-lymphocyte suicide-gene therapy cardiac allograft model in mice

BACKGROUND

Life-long immunosuppression is a major cause of mortality and morbidity in transplant recipients. Gene therapy could provide new ways to obtain tolerance and avoid indefinite immunosuppression. EpTK mice are derived from the FVB/N strain (H2q) and express the thymidine kinase gene of herpesvirus in all mature T cells. Thus any mature dividing T cell can be killed in the presence of ganciclovir. We investigated the survival of alloincompatible C57B1/6 (H2b) hearts heterotopically transplanted into EpTK mice given only ganciclovir from day 0 to day 7 or 14.

METHODS

Abdominal cardiac transplantations were performed in 22 control mice (untreated FVB [n = 15], ganciclovir-treated FVB [n = 5], and untreated EpTK mice [n = 2]) and in 28 EpTK mice given ganciclovir from day 0 to day 7 (n = 15) or day 14 (n = 13). Rejection was defined as complete cessation of cardiac beat. Histologic examination of the grafts was performed at rejection, at day 7, or at day 100. Lymphocyte proliferation assays (concanavalin A stimulation or mixed lymphocyte reaction) were performed at day 7 and at day 100.

RESULTS

All control animals rejected transplants in 7 days (range, 5-9 days), whereas indefinite survival (>100 days) was observed in 89% of the ganciclovir-treated EpTK group, irrespective of the duration of ganciclovir treatment. Graft histology showed extensive cellular infiltrates with myocyte necrosis and arteritis in the control animals but only a mild infiltrate without necrosis or arteritis in the ganciclovir-treated EpTK group. The proliferative responses of the tolerant mice at day 100 were identical to those of naive mice, including a preserved proliferation against the donor's lymphocytes in mixed lymphocyte reaction.

CONCLUSION

Functional transplantation tolerance of a fully incompatible heart can be achieved without immunosuppressive drugs in this model of suicide gene therapy.

[Left ventricular reconstruction after excision of a large fibroma]

The authors report the case of a 15 year old boy with a large left ventricular fibroma discovered after a series of syncopal episodes due to obstruction to ejection. The first attempt to remove the fibroma in Columbia was only partially successful. In view of the risk of death associated with this type of tumour, it was decided to offer the patient complete excision after a full morphological and functional evaluation of myocardial function and the consequences of the tumour on mitral valve function and on the coronary circulation. The operation was performed under cardiopulmonary bypass and aortic clamping by conventional surgery, associated with reconstruction of the cardiac free wall with a large patch of autologous pericardium which was necessary to avoid cardiac transplantation, the ultimate sanction in this indication.

Single breath exhaled nitric oxide in lung transplant patients: a preliminary clinical study

Exhaled nitric oxide is considered as a marker of airway inflammation. We report here our preliminary experience with single-breath exhaled nitric oxide measured in lung transplant patients with and without bronchiolitis obliterans syndrome and in cardiac transplant patients. Peak and end-expiratory nitric oxide concentrations did not differ between groups, but single-breath exhaled nitric oxide recordings were strikingly different in patients suffering from bronchiolitis obliterans syndrome, with a slower decrease from peak to end-expiratory nitric oxide concentration. Further studies are required in order to determine whether theses abnormalities reflect the inflammatory process of bronchiolitis obliterans syndrome.

A stable isotope method using a [(2)H(5)]glycerol bolus to measure very low density lipoprotein triglyceride kinetics in humans

We have developed a method using a bolus of [(2)H(5)]glycerol to determine parameters of VLDL-triglyceride (VLDL-TG) turnover and have compared the data to that obtained using simultaneously a bolus of [2-(3)H]glycerol in six young normolipidemic men. No measurable enrichment was found after 12 h for [(2)H(5)]glycerol; therefore, we could only perform a monoexponential analysis of its data. No differences in fractional catabolic rate (FCR) were seen when comparing the multicompartmental modeling of [2-(3)H]glycerol data (modeled over 48 h) either to the monoexponential analyses of the [2-(3)H]glycerol or that of the [(2)H(5)]glycerol data. The two monoexponential approaches were highly correlated (r = 0.96 for FCR), however, FCR was 18% higher with the [(2)H(5)]glycerol than with the [2-(3)H]glycerol data (P < 0.003). In all six subjects, a 10-h infusion of [1-(13)C]acetate was started at the same time as the glycerol boluses were given. In two men we were able reliably to detect VLDL-TG-fatty acid enrichment. The measurement of FCR in these two subjects using the mass isotopomer distribution analysis (MIDA) approach was in good agreement (within 10%) with FCRs determined with the labeled glycerol methods. In conclusion, our results have shown that results obtained with the [(2)H(5)]glycerol bolus were highly correlated with those obtained with the [2-(3)H]glycerol, but the FCRs were slightly higher with the former. We have also demonstrated that FCRs determined from monoexponential modeling were in good agreement with those determined from the multicompartmental modeling of the TG-glycerol data.

[Stenotrophomonas maltophilia endocarditis following mitral valve prosthesis implantation. Report of a case]

The authors report the first case of early postoperative endocarditis after mitral valvuloplasty due to Stenotrophomonas Maltophilia, a Gram negative organism, in a 37 year old man with no special risk factors. Pyrexia and mitral valve vegetations were the main features, and, in the absence of complications or of embolism, the patient was treated initially with triple antibiotherapy (ceftazidime, amikacine, ciprofloxacine). Relapse two weeks after withdrawal of treatment due to two variants of Stenotrophomas Maltophilia, one of which was resistant to ciprofloxacine, and the presence of a large vegetation, required repeat mitral valvuloplasty and a change in antibiotic therapy (ticarcilline with clavulanic acid, trimethoprim sulphamethoxazole, colistine). This time, the outcome was good. The little known Stenotrophomonas Maltophilia infectious endocarditis is a serious complication and, in the absence of standardised management, the authors suggest that, in view of the multi-resistant character of the organism and in the light of this case, surgery should be considered in association with prolonged antibiotic therapy.

Comparison of the acute hemodynamic effects of hypertonic or colloid infusions immediately after mitral valve repair

OBJECTIVE

To determine the acute hemodynamic effect of hypertonic saline and/or colloid solutions as volume resuscitation in postoperative mitral valve repair patients.

DESIGN

Prospective, randomized trial.

SETTING

Postoperative cardiac intensive care unit of Broussais Hospital.

PATIENTS

Twenty-six patients who underwent mitral valve repair were prospectively studied. Two patients were excluded during the study.

INTERVENTIONS

During the immediate postoperative period, when wedge pressure decreases to <8 mm Hg, patients were randomly assigned to receive 250 mL of either hypertonic saline 7.2%-hydroxyethyl starch 6% (molecular weight, 200,000; hydroxyethylation ratio, 0.5) solution (HS-HES group), hypertonic saline 7.2% solution (HS group), or hydroxyethyl starch 6% solution (HES group). The infusion was completed within 15 mins. No additional volume was infused throughout the study.

MEASUREMENTS AND MAIN RESULTS

Standard hemodynamic measurements and echocardiographic data demonstrated that HS-HES and HS induced a higher increase in left ventricular end-diastolic area than HES. In the HS-HES and HS groups, systemic vascular resistances decreased significantly and end-systolic area tended to decrease. In the HES group, systemic vascular resistances did not change and end-systolic area tended to increase. Accordingly, ejection fraction increased significantly by 21% and 18% with HS-HES (from 50.5 +/- 5.5 to 61.2 +/- 4.8) and HS (from 49.7 +/- 3.6 to 58.8 +/- 3.3), respectively, and did not change with HES. A major increase in cardiac index was observed after hypertonic solutions infusion, from 2.9 +/- 0.3 to 4.1 +/- 0.4 L/min/m2 in the HS-HES group and from 2.7 +/- 0.3 to 3.8 +/- 0.4 L/min/m2 in the HS group. Then, cardiac index progressively returned to baseline values within the 3 hrs after the infusion. No significant difference was observed between HS-HES and HS. In these groups, plasma sodium increased significantly after the infusion and remained higher than baseline values throughout the study. Adverse events were observed only with hypertonic solution administration: hypotensive episodes, sudden increases in pulmonary capillary wedge pressure, and ventricular arrhythmias. These side effects are likely attributable to a too-high dose and/or rate of infusion. All patients included in the study were discharged from the hospital before the 10th postoperative day.

CONCLUSION

We conclude that in patients who have undergone mitral valve repair, postoperative infusion of hypertonic saline solutions increases left ventricular preload and left ventricular ejection fraction. The use of these hypertonic solutions may be of interest in patients with valvular cardiomyopathy. A titrated dose and a low rate of infusion may substantially improve the safety.

Effect of time of day on force variation in a human muscle

The effect of time of day on the neural activation and contractile properties of the human adductor pollicis muscle was investigated in 13 healthy subjects. Two different times of day were chosen, corresponding to the minimum (7 h) and maximum (18 h) levels of strength. The force produced was compared with the associated electromyographic (EMG) activity during voluntary and electrically induced contractions in order to determine whether peripheral or central mechanisms play a dominant role in diurnal force fluctuation. The results indicated that the force produced during a maximum voluntary contraction (MVC) was significantly higher (+8.9%) in the evening than the morning. Since the increase in force of the MVC and the tetanic contraction (100 Hz) were similar, it is suggested that peripheral mechanisms are responsible for diurnal fluctuations in force. This conclusion is supported by the observation that central activation, tested by the interpolated twitch method during an MVC, did not change, and that the EMG was less per unit force in the evening. In addition to the increase in maximum twitch and tetanus force, significant changes in muscle contractile kinetics were also observed. The maximum rate of tension development and the relaxation of the twitch and tetanus increased in the evening, and the twitch contraction time (CT) and the time to half-relaxation (TR(1/2)) were reduced. Because the mean range of variation in skin temperature (2. 6 degrees C) observed over the course of the day was very low, this change cannot entirely explain those observed in muscle contractile properties.

[Intracranial arachnoid cysts. A review]

The diagnosis of arachnoid cyst has become easier and more frequent with the general use of CTscanner and MRI. Their congenital origin is usually accepted. They correspond to liquid formations surrounded by an arachnoid sheet but their pathophysiologie remains unclear. When they are asymptomatic and incidentally discovered, they do not require any peculiar treatment. Variable neurological signs depending on location may be inaugural, although intracranial hypertension is the most frequent. The treatment of these symptomatic cysts remains surgical. Several options are possible: direct approach of the cyst, derivation of the cyst with different modalities, or endoscopic fenestration. This last technique, the most recent, seems to give interesting results especially for deep located cysts or those close to the ventricles.

[Informatics, robotics and medicine]

Information technology is becoming common use in Medicine. Among the numerous applications are data processing, image analysis, 3D reconstruction, telemedicine, to mention only few of them. The interest of computers in surgical research and development is lesser known. Two examples are given: computer aided conception and simulation of physiologic systems. Robotics has been introduced more recently. There are three types of robotics corresponding to three types of use: targetting used by neural surgeons to localize tumors or anatomical structures, visualization used by general surgeons to hold and mobilize laparoscopes, instrumentation introduced more recently by cardiac surgeons to perform totally endoscopic cardiac operations. All these techniques open new ways for tomorrow "Instrumental Medicine".

Endoscopic coronary artery bypass grafting with the aid of robotic assisted instruments

OBJECTIVE

The development of endoscopic coronary artery bypass grafting has been limited because of poor visualization and increased technical difficulties in carrying out operations through ports. We investigated whether the use of robotic assisted instruments could minimize these difficulties.

METHODS

After a period of technical development and training on cadavers (n = 8) with the Intuitive Surgical system (Intuitive Surgical, Inc, Mountain View, Calif), the first clinical application in coronary artery surgery was performed in 4 male patients (mean age 59 +/- 6 years) with the indication of grafting the left internal thoracic artery to the left anterior descending coronary artery. Robotic assisted 3-dimensional endoscopes and instruments were introduced into the left side of the chest through 3 intercostal ports. The Heartport system (Heartport, Inc, Redwood City, Calif) was used for arresting the heart during the anastomosis.

RESULTS

In 2 patients, the harvesting of the left internal thoracic artery was completed endoscopically with robotic assisted instruments and the anastomosis to the left anterior descending artery was performed through a minithoracotomy with conventional instruments. In 2 other patients, the entire operation was completed endoscopically with robotic assisted instruments. Early postoperative coronary angiography demonstrated the patency of the grafts in all cases. At 6-month follow-up, all patients were free of symptoms.

CONCLUSIONS

Robotic assisted instruments make endoscopic coronary bypass possible and open a new era in minimally invasive surgery.

Acute enhancement of insulin secretion by FFA in humans is lost with prolonged FFA elevation

The in vivo effect of elevated free fatty acids (FFA) on beta-cell function in humans remains extremely controversial. We examined, in healthy young men, the acute (90 min) and chronic (48 h) effects of an approximately twofold elevation of plasma FFA vs. control on glucose-stimulated insulin secretion (GSIS). GSIS was studied in response to a graded intravenous glucose infusion (peak plasma glucose, approximately 10 mmol/l, n = 8) and a two-step hyperglycemic clamp (10 and 20 mmol/l, n = 8). In the acute studies, GSIS was significantly higher, insulin sensitivity index (SI) was lower, and disposition index (DI = insulin sensitivity x insulin secretion) was unchanged with elevated FFA vs. control [2-step clamp: DI = 8.9 +/- 1.4 x 10(-3) l2. kg-1. min-2 in control vs. 10.0 +/- 1.9 x 10(-3) l2. kg-1. min-2 with high FFA, P = nonsignificant (NS)]. In the chronic studies, there was no difference in absolute GSIS between control and high FFA studies, but there was a reduction in SI and a loss of the expected compensatory increase in insulin secretion as assessed by the DI (2-step clamp: DI = 10.0 +/- 1.2 x 10(-3) l2. kg-1. min-2 in control vs. 6.1 +/- 0.7 x 10(-3) l2. kg-1. min-2 with high FFA, P = 0.01). In summary, 1) acute and chronic FFA elevation induces insulin resistance; 2) with acute FFA elevation, this insulin resistance is precisely countered by an FFA-induced increase in insulin secretion, such that DI does not change; and 3) chronic FFA elevation disables this beta-cell compensation.

Triglyceride enrichment of HDL enhances in vivo metabolic clearance of HDL apo A-I in healthy men

Triglyceride (TG) enrichment of HDL resulting from cholesteryl ester transfer protein-mediated exchange with TG-rich lipoproteins may enhance the lipolytic transformation and subsequent metabolic clearance of HDL particles in hypertriglyceridemic states. The present study investigates the effect of TG enrichment of HDL on the clearance of HDL-associated apo A-I in humans. HDL was isolated from plasma of six normolipidemic men (mean age: 29.7 +/- 2.7 years) in the fasting state and after a five-hour intravenous infusion with a synthetic TG emulsion, Intralipid. Intralipid infusion resulted in a 2.1-fold increase in the TG content of HDL. Each tracer was then whole-labeled with 125I or 131I and injected intravenously into the subject. Apo A-I in TG-enriched HDL was cleared 26% more rapidly than apo A-I in fasting HDL. A strong correlation between the Intralipid-induced increase in the TG content of HDL and the increase in HDL apo A-I fractional catabolic rate reinforced the importance of TG enrichment of HDL in enhancing its metabolic clearance. HDL was separated further into lipoproteins containing apo A-II (LpAI:AII) and those without apo A-II (LpAI). Results revealed that the enhanced clearance of apo A-I from TG-enriched HDL could be largely attributed to differences in the clearance of LpAI but not LpAI:AII. This is, to our knowledge, the first direct demonstration in humans that TG enrichment of HDL enhances the clearance of HDL apo A-I from the circulation. This phenomenon could provide an important mechanism explaining how HDL apo A-I and HDL cholesterol are lowered in hypertriglyceridemic states.

Resistance to insulin's acute direct hepatic effect in suppressing steady-state glucose production in individuals with type 2 diabetes

We and others have shown that insulin acutely suppresses glucose production in fasting nondiabetic humans and dogs, by both a direct hepatic effect and an indirect (extrahepatic) effect, and in diabetic dogs by an indirect effect alone. In type 2 diabetes, there is resistance to insulin's ability to suppress hepatic glucose production, but it has not previously been determined whether the resistance is primarily at the level of the hepatocyte or the peripheral tissues. To determine whether the diabetic state reduces the direct effect of insulin in humans, we studied nine patients with untreated type 2 diabetes who underwent three studies each, 4-6 weeks apart. 1) Portal study (POR): intravenous tolbutamide was infused for 3 h with calculation of pancreatic insulin secretion from peripheral plasma C-peptide. 2) Peripheral study (PER): equidose insulin was infused by peripheral vein. 3) Half-dose peripheral insulin study (1/2 PER): matched peripheral insulin levels with study 1. In all studies, glucose was clamped at euglycemia, glucose turnover was measured with the constant specific activity method, and 3-[3H]glucose was purified by high-performance liquid chromatography. Peripheral insulin was lower in POR versus PER but slightly higher in POR versus 1/2 PER, although most of the difference could be accounted for by higher proinsulin levels in POR (stimulated by tolbutamide). Calculated portal insulin was approximately 1.3-fold higher in POR versus PER and approximately 2.2-fold higher in POR versus 1/2 PER. In the final 30 min of the clamp, glucose production reached a lower steady-state level in PER than in POR (4.0 +/- 0.4 vs. 5.3 +/- 0.5 pmol(-1) x kg(-1) x min(-1), P < 0.05), despite the higher hepatic insulin level in POR. In contrast with our studies in nondiabetic individuals, glucose production was not more suppressed at steady state in POR versus 1/2 PER (5.3 +/- 0.4 micromol x kg(-1) x min(-1)), despite much higher hepatic insulin levels in POR. In conclusion, this is the first study in patients with type 2 diabetes to characterize insulin resistance to the acute direct suppressive effect of insulin on hepatic glucose production.

Counterregulatory response to hypoglycemia differs according to the insulin delivery route, but does not affect glucose production in normal humans

The magnitude of the counterregulatory response to insulin-induced hypoglycemia is primarily determined by the degree of hypoglycemia. We examined whether the route of acute insulin delivery (portal or peripheral venous) is also important in determining the magnitude of the counterregulatory response to hypoglycemia in nine healthy nondiabetic men. Pancreatic insulin secretion, stimulated by an i.v. tolbutamide infusion (portal insulin study), was matched with an exogenous insulin infusion into the peripheral vein 4-6 weeks later (peripheral insulin study). Each study consisted of a 150-min baseline tracer equilibration period, a 180-min euglycemic hyperinsulinemic (portal or peripheral insulin delivery) period, a 60-min hypoglycemic period in which insulin secretion diminished during tolbutamide or was reduced during exogenous insulin, and a 30-min recovery period. Peripheral venous glucose concentrations were well matched in the portal and peripheral studies during euglycemia and hypoglycemia (glucose nadir, 2.9 +/- 0.1 mmol/L in the portal and 2.7 +/- 0.1 mmol/L in the peripheral; mean +/- SEM; P = NS), and insulin concentrations were about 1.5-fold higher throughout the experiment in the peripheral vs. the portal insulin study due to the first pass extraction of insulin in the portal study. There was a much greater increment (P < 0.0001) in FFA in the portal vs. the peripheral study (area under the curve: portal, 19.5 +/- 3.9 mmol/L x 90 min; peripheral, 3.3 +/- 1.1 mmol/L x 90 min), whereas plasma glucagon and GH were higher in the peripheral study (P = 0.01 for glucagon; P = 0.015 for GH). There was no significant difference between studies in epinephrine and norepinephrine responses to hypoglycemia or stimulation of endogenous glucose production (area under the curve: portal, 636 +/- 103 micromol/kg x 90 min; peripheral, 705 +/- 69 micromol/kg x 90 min; P = NS). In summary, we have shown that the glucagon, GH, and FFA responses to hypoglycemia during insulin dissipation are affected by the route of insulin delivery and are not controlled exclusively by the nadir blood glucose level. The clinical importance of these observations in diabetic subjects as they relate to route of insulin delivery (portal or peripheral) during insulin dissipation remains to be determined.

[The pericardium: a heterogeneous tissue. Anatomic and morphometric considerations]

BACKGROUND AND AIMS OF THE STUDY

Short-term glutaraldehyde fixed autologous pericardium is widely used in cardiac valve repair or in autologous pericardial bioprosthesis construction. The thinner the tissue, the better the fixation. The aim of this study was to determine thickness and useful surface area of pericardium in relation to harvesting site using a digital thickness counter (0.01 mm precision). Parietal pericardium fragments were obtained from the pericardial sac of six fresh cadavers (group I). In the other groups, pericardial strips (80 x 30 mm) were obtained from patients undergoing surgery: group II patients (n = 5 females) and group III (n = 10 males) were non-cardiomegalic (cardiothoracic ratio (CTR) < 0.5)), while group IV patients (n = 5) were all cardiomegalic (CTR > 0.5). Results were reported on a coloric scale according to measurement position. In group I, mean surface area was 93 +/- 18 cm2, and thickness gradually increased from 0.1 to 0.6 mm, maximally on the diaphragm, along the left heart side. In other groups, a gradual increase in thickness was identified towards the diaphragmatic zone. Significant differences in tissue thickness appear as a result of cardiomegaly, but are not related to the sex of the patients. Pericardium taken from the right anterior aspect of the pericardial sac in patients without cardiomegaly is the most appropriate tissue for valve reconstructive surgery, due to its thin nature and hence better fixation properties.

Correlation between clinical and histologic patterns of degenerative mitral valve insufficiency: a histomorphometric study of 130 excised segments

The objectives of this study were to examine quantitatively the histological changes in incompetent degenerative mitral valves obtained at surgery for mitral valve repair, and to determine whether Barlow's disease (BD) and fibroelastic deficiency (FED) can be distinguished by histology. The billowing mitral leaflet syndrome (or Barlow's disease) and FED can be distinguished on the basis of clinical patterns and gross features, but their histologic patterns have not been described. One hundred thirty patients were studied. Thirty-nine (24 males) had BD; 44 (38 males) FED; 15 (7 males) Marfan's syndrome (MS); and 32 patients (25 males) a non-determined degenerative disease. Histological changes of the resected segment of the valve were quantitatively evaluated using scores of severity. A discriminant analysis was performed. The groups defined by the computer were checked for concordance with groups defined by the surgeon. Collagen alterations were found the most severe in MS patients. BD and MS had the most myxoid infiltration. MS and FED patients had the most elastic fiber alterations. No BD in males and only one in females were misclassified by the discriminant procedure into the FED group. Overall, the percentages of correct matchings were 54% in males and 62% in females. When the age of patients and the size of ring were added to histology to determine whether this additional information provided more discrimination, the percentages of correct matchings reached 90% in males and 100% in females. BD and FED are two fairly distinct entities, which can be distinguished by quantitative histology, whereas only modest differences were found in qualitative histology.

Load-dependent muscle strategy during plantarflexion in humans

This study analyses the relative contribution of the triceps surae and tibialis anterior (TA) muscles to tension development with reference to voluntary plantarflexion at two articular positions of the knee joint (extended and flexed at 90 degrees) for various inertial loads. Subjects were instructed to perform plantarflexions at various sub-maximal and maximal velocities with no intention of stopping the movement. Whereas in one series of experiments the subjects were informed of the load countering the movement, in the other they were not. The average electromyographic (EMG) activity of the different muscles was recorded. The main results were that with loading: (a) greater maximal plantarflexion velocities were recorded in flexed as compared to extended-knee positions; (b) greater durations and amplitudes of agonist and antagonist EMG bursts were recorded; (c) the co-activation of the TA and triceps surae muscles was enhanced; (d) unexpected sub-maximal loads induced greater EMG activity and speed of movement. It is concluded that increasing the load during plantarflexion in humans brings about changes in neuromuscular strategies that contribute to the efficiency of contractile activity during rapid movements. The results also indicate that unexpected sub-maximal loading induces a potentiated neuromuscular activity which increases the speed of movement.

[Importance of dual isotope myocardial tomoscintigraphy in the detection of coronary disease in the graft among 96 heart transplant recipients]

With a survival rate of 70% at 3 years, cardiac transplantation is the best treatment for end-stage heart disease. However, progressive development of graft atherosclerosis is frequent. Diagnosis of transplant coronary disease remains difficult and non-invasive tests have proved relatively insensitive. Therefore, coronary angiography performed annually is still the gold-standard test for the detection of heart transplant vasculopathy. We analyzed the records of 96 patients (82 men and 14 women) who were transplanted from 1986 to 1996. Mean age was 53 +/- 2.7 and time elapsed from transplantation was mean 5.3 +/- 10 years. All patients had rest myocardial TI 201 perfusion SPECT, followed by MIBI gated SPECT after exercise. MIBI gated SPECT allows simultaneous evaluation of perfusion, regional LV function and global ejection fraction. Angiocoronarography, performed in all patients during the six months following radionuclide investigation, showed the presence of coronary heart vasculopathy in nine (9.3%). Seven of these patients had abnormal dual isotope imaging and 2 of them had normal perfusion but altered LV regional function. Sensitivity of dual isotope scintigraphy was 77% and specificity was 97.7%. Dual isotope scintigraphy is helpful to detect coronary vasculopathy in heart transplant recipients and may reduce indications of angiocoronarography.

Cardiac valve papillary fibroelastoma: surgical excision for revealed or potential embolization

OBJECTIVE

We have reviewed the case histories of 4 patients who underwent operations between September 1994 and November 1997 at Broussais Hospital for cardiac valvular papillary fibroelastoma.

METHODS

Diagnosis was strongly suggested by echocardiography. Tumor locations were mitral (1), tricuspid (1), and aortic (2). Indications for operation were previous stroke for the mitral tumor, prophylaxis for the tricuspid tumor, syncopal episodes for the first aortic tumor, and transient ischemic attack and mesenteric ischemia for the second aortic tumor.

RESULTS

Surgical excision with a conservative, valve-sparing approach was performed in all cases. For the first aortic tumor, aortic valve reconstruction was achieved with part of a cryopreserved aortic homograft cusp. Intraoperative transesophageal echocardiography showed no evidence of valvular regurgitation after excision in all cases. All patients had uneventful postoperative recoveries. No evidence of regurgitation or recurrence was seen on echocardiography at follow-up.

CONCLUSIONS

Despite their histologically benign aspect, cardiac papillary fibroelastomas should be excised because of potential embolic complications. A conservative, valve-sparing approach is recommended, however, because of the absence of recurrence after total excision.

The radial artery for coronary artery bypass grafting: clinical and angiographic results at five years

OBJECTIVE

The aim of this study was to assess the long-term results of use of the radial artery as a conduit for coronary artery bypass grafting.

METHODS

After revival of the technique in 1989, the radial artery was used as a conduit in 910 patients undergoing coronary artery bypass grafting. A complete follow-up was obtained for the first 102 consecutive patients from 4 to 7 years after the operation (mean 5.27 +/- 1.30 years). Fifty-nine percent of the patients were receiving calcium-channel inhibitors. An electrocardiographic stress test was obtained for 51 patients, with no contraindications found. Routine follow-up angiography was performed in 50 cases, including those of all patients with symptoms. Thus 64 radial artery and 48 left internal thoracic artery grafts were followed up from 4 to 7 years after the operation (mean 5.6 +/- 1.40 years).

RESULTS

The actuarial survival was 91.6% at 5 years, and the actuarial rate of freedom from angina was 88.7% at 5 years. Four patients underwent percutaneous transluminal angioplasty during the period of follow-up, and there were no reoperations for revision of the bypass. The electrocardiographic stress test showed negative results in 73% of cases, electrocardiographic changes alone in 21%, and clinically positive results in 6%. Angiography showed that the patency rate of the radial artery grafts was 83%. The patency rate of the left internal thoracic artery grafts (n = 47) was 91%. The difference in patency could be related to the implantation sites of the grafts, mainly the circumflex artery (51%) for the radial artery grafts and almost exclusively the left anterior descending artery (94%) for the left internal thoracic artery.

CONCLUSION

The use of the radial artery for coronary bypass grafting provides excellent clinical and angiographic results at 5 years. Routine use of the radial artery in combination with the left internal thoracic artery can be recommended.

New approach for reconstruction of the pulmonary outflow tract during the Ross procedure

BACKGROUND

This study describes and evaluates the early results of a new surgical technique to reconstruct the right ventricular outflow tract and fit it with a new valve after the Ross procedure.

METHODS AND RESULTS

Between March 1996 and November 1997, 20 patients underwent a Ross operation with a new approach consisting of a direct anastomosis between the remaining pulmonary artery trunk and the infundibulum and of the creation of a monocusp tailored from the anterior pulmonary artery wall as a means of reconstructing the valve. The 20 patients (12 males and 8 females) had a mean age of 27.4 years (range, 17 to 42 years). Ten of them had predominant aortic regurgitation, 8 had aortic stenosis, and 2 had mixed disease. There were no deaths during the follow-up period of up to 20 months, no early or late repeat operations, and no specific complications secondary to the surgical technique. During the follow-up, at the aortic autograft site, 19 patients had no or trivial regurgitation, and a mild regurgitation was found in only 1 patient. Across the pulmonary monocusp, color flow Doppler demonstrated no or trivial incompetence in 10 patients, mild incompetence in 7, and moderate incompetence in 3. No significant pressure gradient was shown.

CONCLUSIONS

Our experience supports the use of this new surgical procedure and allows extension of the Ross operation to where there are no facilities for homografts. It may be an alternative for right ventricular outflow tract reconstruction with a homograft should the results be confirmed at long-term follow-up.

[Coronary reoperation: indications, methods and immediate postoperative prognosis. Retrospective study of 184 reoperations]

The authors performed 184 coronary reoperations (172 redux, 12 tridux) between January 1986 and december 1995 in 177 patients (165 men, 12 women) with an average age at surgery of 62.9 +/- 7.6 years. The average interval between the surgical procedures was 9.5 +/- 4.5 years. The symptoms were recurrent angina, stable in 44%, unstable in 51%, and cardiac failure, 7%. Graft dysfunction was the cause in 94.5% of cases with progression of atheroma of the native coronary vessels in only 5.6% of cases. At reoperation 389 bypass procedures were performed (venous 39.5%, arterial 60.5%) (2.1 +/- 0.6 per patient) with 10 associated procedures (3 mitral valvuloplasties, 2 left ventricular aneurysmectomy, 3 aortic valve replacements, 1 replacement of the ascending aorta, 1 carotid endarteriectomy). The operative mortality was 10.9%. The causes of the 20 deaths were myocardial infarction (7), left ventricular failure (8), arrhythmias (2), mediastinitis (1) and multi-organ failure (2). The risk factors for death were: the date of surgery (19% before 1991 and 8% after: p = 0.03), age (18% after 60 years, 2% before: p = 0.015), the interval between the surgical procedures (33% after 15 years, p = 0.02), anterograde cardioplegic injection alone (15% versus 4.5% when mixed antero and retrograde perfusion was used: p = 0.02). The morbidity was 28% (52/184 patients); 132 patients (72%) had uncomplicated postoperative courses. The incidence of repeat coronary artery surgery is in constant progression. Improved medico-surgical management should continue to reduce the mortality which is still high.

Aortic valve surgery in osteogenesis imperfecta: report of two cases and review of the literature

Aortic insufficiency is a well known but uncommon valvular dysfunction in patients with osteogenesis imperfecta. In such cases, aortic valve surgery has rarely been performed, and carries a high risk of perioperative complications. We report two patients with osteogenesis imperfecta, who underwent elective successful aortic valve replacement. The surgical problems encountered in this connective tissue disorder are also reviewed.

Preoperative localization of parathyroid lesions in hyperparathyroidism: relationship between technetium-99m-MIBI uptake and oxyphil cell content

The aim of this study was to assess the relationship between parathyroid oxyphil cell content and early or late phases of uptake of 99mTc-MIBI, a radioisotope preferentially retained in mitochondria-rich cells.

METHODS

This study is a retrospective, single-blind analysis of all double-phase 99mTc-MIBI parathyroid scintigraphy studies performed before surgery in our institution between 1990 and 1995. A total of 18 parathyroid lesions in 14 patients were reviewed. This sample included 11 cases of primary hyperparathyroidism (8 adenomas, 1 adenocarcinoma and 2 hyperplasias) and 3 cases of tertiary hyperparathyroidism secondary to chronic renal failure.

RESULTS

Uptake of 99mTc-MIBI in the early phase of scintigraphy was associated with larger parathyroid lesions (1.61 +/- 1.61 ml versus 0.33 +/- 0.27 ml; p < 0.02) and higher serum calcium levels (3.00 +/- 0.41 mM versus 2.67 +/- 0.14 mM; p < 0.02). More importantly, we found that a parathyroid oxyphil cell content greater than 25% was more often associated with a positive uptake of 99mTc-MIBI in the late phase of the test (positive late uptake in 78% of lesions with a high oxyphil cell content versus 33% in lesions with an oxyphil cell content between 1% and 25% and 0% in lesions with no oxyphil cells; p < 0.04).

CONCLUSION

These findings suggest that the late retention of 99mTc-MIBI in double-phase scintigraphy is related to parathyroid oxyphil cell content.

Bi-directional cavopulmonary shunt associated with ventriculo and valvuloplasty in Ebstein's anomaly: benefits in high risk patients

OBJECTIVE

The prognosis for surgical repair of Ebstein's anomaly depends on the tricuspid valve repair and on the right ventricular function. In order to decrease the preload of the compromised right ventricle, a bi-directional cavopulmonary shunt was added to the intracardiac repair.

METHODS

Among 113 patients operated on for Ebstein' s anomaly at our institution from 1980-1997, a cohort of 60 patients was selected for high risk for postoperative complications. Patients presented with one or more several criteria: massive tricuspid valve dysfunction, extended atrialized right ventricle, poor right ventricular contractility, or long standing atrial fibrillation. After prior informed consent, this cohort was divided into two groups. Both groups had similar preoperative clinical patterns: Group I (45 patients), surgical technique included longitudinal right ventricular plication and tricuspid valve valvuloplasty; Group II (15 patients), where the surgical technique was similar to Group I except a bi-directional cavopulmonary shunt was added at the end of the procedure.

RESULTS

Operative mortality was 24% (11/45) in Group I and 0% (0/15) in Group II (P < 0.05). The survival at 5 years was 66.1 +/- 14% in Group I and 80 +/- 16% in Group II (not significant). Reoperation rate was 11% (5/45) in Group I and 0% (0/15) in Group II. No deleterious effects of the bi-directional cavopulmonary shunts were observed clinically. Residual tricuspid valve insufficiency rate was 26% in both groups. However, patients with the bi-directional cavopulmonary shunt had a better tolerance and have not needed reoperations to date.

CONCLUSIONS

In high risk patients with Ebstein's anomaly, an associated bi-directional cavopulmonary shunt seems to offer several distinct advantages including decreased operative mortality and better tolerance of the residual tricuspid valve dysfunction.

[Cavo-pulmonary anastomosis associated with intracardiac repair of Ebstein anomaly. Value in high-risk patients]

The surgical prognosis of Ebstein's anomaly depends on the quality of tricuspid valve repair and right ventricular function. In patients with right ventricular failure, a decrease in afterload was attained by a cavo-bipulmonary anastomosis associated with the intraventricular repair. Fifty-nine out of 111 patients operated for Ebstein's anomaly were considered to be at high risk and were selected for this study. The inclusion criteria were one or more of the following factors: massive tricuspid regurgitation, extensive atrialisation of the right ventricle, poor right ventricular function, chronic atrial fibrillation. This population was divided into two groups with the same preoperative features: Group I (45 operated patients: tricuspid valvuloplasty with longitudinal plicature of the right ventricule: Group II (14 operated patients): same intracardiac repair as Group I and associated cavo-bipulmonary anastomosis. The operative mortality was 24% (11/45) in Group I and 7% (1/14) in Group II (p < 0.05). The 5 year actuarial was 68.6% in Group I and 61.8% in Group II (NS). The reoperation rate was 11% (5/45) in Group I and 0% in Group II. In Group II, the persistence of significant tricuspid regurgitation was better tolerated and the frequence of reoperation was decreased with respect to Group I. The authors conclude that high risk patients with Ebstein's anomaly have a lower operative mortality and improved functional tolerance when there is persistent tricuspid regurgitation after cavo-bipulmonary anastomosis.

[Computer assisted open heart surgery. First case operated on with success]

The recent development of less invasive intracardiac surgery using small incisions and videoscopic techniques allowed an evaluation of the advantages and limitations of this new approach. Among the limitations was the increased difficulty of the surgical technique when using long instruments through small incisions and ports. We investigated whether computer assisted surgical instruments might bring a solution to this problem. Among the existing systems, we selected the Intuitive System because of two original features. It provides a stable, magnified, three dimensional view of the operating field at a console where the surgeon is seated to operate, and it uses computer assisted instruments having the same dexterity and range of motion as the hand. After 10 months of active work to adapt this system to intracardiac surgery, the first open heart operation using computer assisted instruments was carried out on a 52-year-old woman presenting an aneurysm and a large defect of the atrial septum. The patient was extubated 8 h after the operation, returned to her room 16 h later and was discharged from the hospital 8 d post-operatively with normal heart function and no residual shunt. This preliminary experience showed that computer assisted cardiac surgery is feasible and may open new and promising directions in open heart surgery.

Less invasive techniques for mitral valve surgery

OBJECTIVE

Minimally invasive surgical techniques aim at reducing the consequences of currently used large incisions, such as bleeding, pain, and risk of infection. Although this new approach developed rapidly in coronary surgery, it remains questionable in mitral valve surgery. This article reports the longest experience with minimally invasive mitral valve surgery, with particular attention to approach and techniques.

METHODS

From February 1996, the date of the first case of minimally invasive mitral valve reconstruction, to April 1997, 22 patients with a mean age of 54 +/- 2.7 years were subjected to mitral valve surgery performed with less invasive techniques. Exposure of the mitral valve was achieved through a minithoracotomy (n = 12) or a ministernotomy (n = 10). Video assistance was used in all cases. Peripheral arterial cannulation (n = 21) and venous drainage (n = 22) were used in most cases.

RESULTS

In this series, valve surgery consisted in 19 repairs, two replacements, and one closure of a periprosthetic leak. In two cases it was necessary to convert to a larger incision. The average duration of cardiopulmonary bypass was 157 +/- 8.2 minutes, ventilatory assistance 16 +/- 4.6 hours, and intensive care unit stay 2.1 +/- 0.4 days. Two patients required reoperation for bleeding and another for early recurrence of mitral valve regurgitation. There were no deaths and all patients were discharged with normal valve function. At most recent follow-up, all patients were in functional class I, with resumption of normal activity.

CONCLUSION

Mitral valve surgery can be performed safely by means of less invasive techniques, but with increased technical difficulty. A low asymmetric median sternotomy seems preferable to an anterior thoracotomy.

[Effects on myointimal proliferation of an antisense oligonucleotide directed against c-myb: specificity of action and consequences on vasoreactivity]

Several reports have shown that an antisense oligonucleotide directed against c-myb (AS 18) inhibits the proliferation of smooth muscle cell. The aims of this study were to confirm the specificity of a new c-myb antisens and to evaluate changes in vasoreactivity following treatment with a c-myb antisense. Five groups of rats were constituted. All underwent desendothelialisation of the abdominal aorta. A solution containing pluronic gel, or one of the following oligonucleotides: AS 18, 15 mere antisense directed against c-myb, an aleatory 4G sequence containing 4 consecutive guanosines, a 15 mere antisense mismatch (n = 11), was applied around the aorta. After 21 days, the thickness and mean surface areas of the media and intima were calculated. Four groups of rats were constituted for the reactivity study: control (A), desendothelialisation (B), desendothelialisation + application of AS 18 (C), and application of AS 18 alone (D). One ring per aorta was sampled at the 21st day and analysed in an organ chamber. The following results were obtained: the thickness and average surface areas of the intima were smaller (p < 0.05) in the 4G and AS 18 groups; in group B, none of the 8 segments responded to acetylcholine; in group C, 6 out of 8 segments responded. The contraction study showed no difference between groups A and D or between B and C. The mode of action of AS 18 antisense of c-myb is non specific but due to the presence of 4 consecutive guanosines in the oligonucleotide. Oligonucleotide with this sequence inhibits myo-intimal hyperplasia and improves endothelium-dependent relaxation in this model without affecting the contraction.

The activity of c-myb antisense oligonucleotide to prevent intimal hyperplasia is nonspecific

BACKGROUND

We sought to determine the efficacy and specificity of a new c-myb antisense by inhibiting neointimal hyperplasia in a rat abdominal aorta injury model. Using c-myb antisense oligonucleotides, inhibition of vascular smooth muscle cell proliferation has been reported.

METHODS

Sixty-six male Wistar rats had a de-endothelialization of the abdominal aorta. Following a double blind randomization protocol, F127 pluronic gel containing one of the five oligonucleotides or plain gel was applied around the aorta: 1) 18-mer c-myb antisense (AS18) with four contiguous guanosines (G-quartet); 2) 15-mer c-myb antisense (AS15) without G-quartet; 3) 1-bp mismatch AS15 without G-quartet (MM1); 4) an oligonucleotide with G-quartet (4G), whereas the other bases were chosen at random; 5) 1-bp mismatch 4G without G-quartet (MM2). After 21 days all rats were sacrificed and aortas harvested for histomorphometric evaluation. Four rats were given fluorescent-labeled oligonucleotides to study in vivo localization after local advential delivery.

RESULTS

Morphometric analysis showed significant suppression of neointimal hyperplasia in AS18 and 4G and MM2 groups compared with GEL, AS15 and MM1 groups (p<0.05). The oligonucleotide-labeled aortas showed penetration of the oligonucleotides into the media which increased with time.

CONCLUSIONS

Our findings pointed to the potential non specificity of the c-myb antisense oligonucleotide in vivo. Such results will minimize the importance of antisense strategy as a potential therapeutic for preventing neointimal hyperplasia. The two oligonucleotides with a G-quartet inhibited neointimal hyperplasia in our model. Exploring a non-antisense mechanism, G-quartet oligonucleotides as potential drugs to reduce neointimal hyperplasia is attractive.

Autologous pericardial patch harvesting site for cardiac valve repair: anatomic and morphometric considerations

BACKGROUND AND AIMS OF THE STUDY

Short-term glutaraldehyde-fixed autologous pericardium is widely used in cardiac valve repair or in autologous pericardial bioprosthesis construction. The thinner the tissue, the better the fixation. The aim of this study was to determine thickness and useful surface area of pericardium in relation to harvesting site using a digital thickness counter (0.01 mm precision).

METHODS

Parietal pericardium fragments were obtained from the pericardial sac of six fresh cadavers (group I). In the other groups, pericardial strips (80 x 30 mm) were obtained from patients undergoing surgery: group II patients (n = 5 females) and group III (n = 10 males) were non-cardiomegalic (cardiothoracic ratio (CTR)<0.5), while group IV patients (n = 5) were all cardiomegalic (CTR >0.5).

RESULTS

Results were reported on a coloric scale according to measurement position. In group I, mean surface area was 93+/-18 cm2, and thickness gradually increased from 0.1 to 0.6 mm, maximally on the diaphragm, along the left heart side. In other groups, a gradual increase in thickness was identified towards the diaphragmatic zone. Significant differences in tissue thickness appear as a result of cardiomegaly, but are not related to the sex of the patients.

CONCLUSIONS

Pericardium taken from the right anterior aspect of the pericardial sac in patients without cardiomegaly is the most appropriate tissue for valve reconstructive surgery, due to its thin nature and hence better fixation properties.

Mechanical modifications to human pericardium after a brief immersion in 0.625% glutaraldehyde

BACKGROUND AND AIMS OF THE STUDY

The use of human pericardium pretreated for 10 min with 0.625% glutaraldehyde (GLUT) in valvular repair or intracardiac reconstruction has produced good results. However, to date, no investigations have been made to determine the mechanical changes that occur in the tissue following such pretreatment.

METHODS

Human pericardial samples were harvested from 25 patients and immersed in GLUT for increasing times (5, 10, 30, 60 min and 6 months). Either untreated human pericardium or bovine pericardium treated for six months with GLUT served as controls. Tensile tests were performed with a uniaxial load machine and a pulsative bench. Fatigue testing was for 14 days; each sample was tested at 1,200 cycles/min at a controlled pressure of 90-120 mmHg.

RESULTS

Untreated tissue thickness was 0.44+/-0.16 mm, but after six months GLUT treatment it was 0.53+/-0.15 mm (p<0.001). There was a 13.7% shrinkage of tissue after six months immersion. Strain was significantly greater in treated tissue than in untreated tissue, while stiffness decreased with the duration of GLUT immersion. Young's modulus was significantly lower after six months GLUT treatment (0.26+/-0.06 MPa) compared with untreated, and 5-, 10- and 30-min GLUT treatment (0.32+/-0.15, 0.35+/-0.09, 0.32+/-0.09 and 0.36+/-0.10 MPa (p<0.05)), respectively. Creep was greater after six months GLUT treatment (0.5+/-0.03%) than in untreated and 10-, 30- and 60-min treatments (0.3+/-0.50, 0.27+/-0.01, 0.27+/-0.02, 0.3+/-0.01% (p<0.05)), respectively. Ultimate tensile stress (UTS) was greater in 10-min treated pericardium than in untreated tissue: 38.46+/-11.75 versus 22.17+/-8.30 MPa (p<0.05) respectively. Strain at rupture was greater in the 6-month group (30.62+/-2.54%) than for untreated and 10-, 30- and 60-min GLUT immersion 16.3+/-0.73, 21.85+/-0.75, 20.12+/-1.04 and 18.87+/-0.86% (p<0.05), respectively. Fatigue testing showed an increased length after five and 10 min, and six months, with a lengthening of 14.66, 12.53, 7.66%, respectively compared with 3.5% for untreated tissue (p<0.05). There were three failures in the untreated group (n = 5), none in the 5- and 10-min groups, and one in the 6-month group (p<0.05).

CONCLUSION

Brief immersion of human pericardial tissue in 0.625% glutaraldehyde reduces the tissue's stiffness and improves its durability for use in cardiac surgery.

Reconstructive surgery in congenital mitral valve insufficiency (Carpentier's techniques): long-term results

BACKGROUND

Previous publications have stressed the benefits of mitral valve repair over mitral valve replacement in children. However, few communications have reported the long-term results and none with a follow-up of more than 10 years. This article reports our results in a series of 145 patients operated on for congenital mitral valve insufficiency by means of the same technique (Carpentier's technique) in a single center.

METHODS

Between 1970 and 1995, 145 patients younger than 12 years old underwent surgery for congenital mitral valve insufficiency. Mean age was 5.7 +/- 3.1 years, ranging from 0.17 to 12 years. Mitral valve insufficiency associated with atrioventricular defect, atrioventricular discordance, straddling mitral valve, acquired diseases, Marfan syndrome, and degenerative disease was excluded from this study. According to Carpentier classification, 31 patients had type I mitral valve disease (normal leaflet motion), 79 patients type II (leaflet prolapse), and 35 type III (restricted leaflet motion), with 15 having normal papillary muscles and 20 abnormal papillary muscles. Associated lesions were present in 51 patients (35%). A conservative operation was possible in 138 patients (95%). Among them, 70 patients required a prosthetic annuloplasty and 21 patients valve extension with a pericardial patch. Valve replacement was necessary in seven patients (5%).

RESULTS

In-hospital mortality was 5% (95% CL: 2.5% to 9.9%) (seven patients). No early death was observed in the group of patients who underwent valvular replacement. In-hospital mortality was as follows: type I, 9.6%; type II, 2.5%; and type III, 13%. No statistically significant difference was noted among patients with the different types of disease. Mean follow-up was 9.3 +/- 6.9 years (1 to 26 years), and cumulative follow-up was 1142 patient-years. Ten late deaths occurred. Actuarial survival at 10 years was 88% in patients who underwent valve repair and 51% in patients who underwent valve replacement. Late reoperation was required in 15% (n = 21) of patients who had undergone valve repair and 28% (n = 2) in patients with valve replacement. Causes of reoperation were recurrent left ventricular failure (n = 1), residual or recurrent mitral valve insufficiency (n = 17), mitral valve stenosis (n = 3), and calcification of the bioprosthesis (n = 2). No failure resulting from leaflet extension was observed. In the repair group, actuarial freedom from reoperation was 68% (95% CL: 80.5% to 51.5%) at 15 years, and the linearized rate of exposure to reoperation was 1.9% per patient-year. No thromboembolic event was observed in any group.

CONCLUSION

Congenital mitral valve insufficiency can be repaired in infancy with a low mortality. Conservative surgery with Carpentier's techniques is feasible in the majority of cases of congenital mitral valve insufficiency. This technique offers stable long-term results with a low rate of reoperation. Leaflet extension associated with prosthetic ring annuloplasty could prevent reoperations in selected cases.

Inhibition of intimal hyperplasia by an antisense oligonucleotide of farnesyl transferase delivered endoluminally during iliac angioplasty in a rabbit model

The major complication of vascular recanalization is intimal hyperplasia which is due mainly to proliferation and migration of smooth muscle cells (SMC). Activation of SMC results from stimulation of protooncogens (c-myb, c-myc, c-fos) by growth factors induced by activated ras-proteins. Ras-proteins become activated after receiving a farnesyl group in a reaction catalyzed by famesyl transferase. The purpose of this study was to test the effectiveness in preventing intimal hyperplasia of an antisense oligonucleotide of the alpha subunit of farnesyl-transferase delivered endoluminally during angioplasty of the common iliac artery in rabbit model. Twenty-one male New Zealand rabbits with a mean weight of 3.3 kg fed a high cholesterol diet underwent bilateral angioplasty of the common iliac artery using hydrogel-coated balloon catheters. On the right side three types of treatment were randomly performed by adding one of the following three oligonucleotides to the hydrogel precoating:antisense oligonucleotide of farnesyl transferase (n = 7), mismatch oligonucleotide (n = 7), and scramble oligonucleotide (n = 7). On the left side hydrogel was used with saline so that each animal served as its own control. Animals were killed 6 weeks after angioplasty and arteries were studied. The thickness and mean surface of the neointima (MTI and MSI) and the ratio (R) of the neointima to neointima + media were calculated. In the scramble and mismatch groups there was no difference between the treated and control arteries with regard to MTI, MSI, or R. In the antisense group mean all three values were significantly lower on the treated side than the control side (EMI: p < 0.02, SMI: p < 0.02, and R: p < 0.01). Treated arteries in the antisense group presented significantly lower EMI (p < 0.02), SMI (p < 0.02), and R (p < 0.01) than treated arteries in the other groups whereas the thickness and mean surface of the media were comparable. Endoluminal administration of an antisense oligonucleotide against the alpha subunit of farneysyl transferase inhibited intimal hyperplasia in our model.

Distinct sensitivity of neuroblastoma cells for retinoid receptor agonists: evidence for functional receptor heterodimers

Retinoic acid (RA) plays a major role in embryogenesis of the nervous system and has been reported to induce differentiation in neuroblastoma cell lines. To identify RA signaling pathways involved in such differentiation processes, two RA-sensitive neuroblastoma cell lines (LA-N-5 and SH-SY5Y) were extensively studied. Northern blot experiments determined that of the three RAR mRNAs, only RARalpha was significantly expressed, with respectively weak or undetectable levels of RARgamma and RARbeta. RXRs (alpha and beta) receptors were weakly expressed. Western blotting analysis confirmed the constitutive expression of RARalpha and absence of RARbeta and weak levels of RXRalpha. Treatment with all-trans-RA up-regulated RARalpha and induced a drastic increase of RARbeta (both at the RNA and protein level). To further characterize the function of RARalpha, RARbeta and RXRalpha in NB cells, nuclear extracts from LA-N-5 cells were analysed by EMSA studies. Three specific retarded complexes were observed which were significantly decreased or shifted in the presence of monoclonal antibodies to RARalpha, RARbeta and RXRalpha. RA treatment dramatically induced a DR5-binding RXRalpha-RARbeta heterodimer. Treatment with combinations of RARalpha or RARbeta agonists with a RXRalpha agonist or with a RARalpha agonist alone, induced neurite-outgrowth supporting the probability that both RXRalpha-RARalpha or RXRalpha-RARbeta heterodimers are involved in RA-mediated differentiation of NB cells. The availability of novel synthetic RA-specific receptor ligands should provide the possibility of tissue specific therapeutic regimes.

Dynamic cardiomyoplasty: clinical follow-up at 12 years

OBJECTIVE

The purpose of this study is to evaluate the long-term outcome of dynamic cardiomyoplasty. This surgical technique was conceived to assist the failing heart. The many proposed mechanisms of action of cardiomyoplasty are: (1) systolic assist; (2) limitation of ventricular dilation; (3) reduction of ventricular wall stress (sparing effect); (4) ventricular remodeling with an active girdling effect; (5) angiogenesis; and (6) a neurohumoral effect.

METHODS

We investigated 95 patients in our hospital undergoing this procedure due to severe chronic heart failure, refractory to optimal medical treatment. Patients had a mean age of 51 +/- 12 years. The etiology of heart failure was ischemic 55%, idiopathic 34%, ventricular tumor 6%, and other 5%. The mean follow-up was 44 months.

RESULTS

The mean New York Heart Association (NYHA) functional class improved postoperatively from 3.2 to 1.8. Average radioisotopic left ventricular (LV) ejection fraction increased from 17 +/- 5 to 27 +/- 4% (P < 0.05). Stroke volume index increased from 32 +/- 7 to 43 +/- 8 ml/beat per m2 (P < 0.05). The heart size remained stable over the long term. Following cardiomyoplasty, the number of hospitalizations due to congestive heart failure was reduced to 0.4 hospitalizations/patient per year (preoperative: 2.5, P < 0.05). Computed tomography scans showed at long term a preserved latissimus dorsi muscle structure in 84% of patients. Survival probability at 7 years is 54%. Six patients underwent heart transplant after cardiomyoplasty (mean delay: 25 months), due to the natural evolution of their underlying heart disease. There were no specific technical difficulties.

CONCLUSIONS

Clinically, this procedure reverses heart failure, improves functional class and ameliorates quality of life. The latissimus dorsi muscle histological structure is maintained at long-term, when postoperative electrostimulation is performed, avoiding excessive stimulation. Cardiomyoplasty may delay or prevent the progression of heart failure and the indication of cardiac transplantation.

Normal human immunoglobulins for intravenous use (IVIg) delay hyperacute xenograft rejection through F(ab')2-mediated anti-complement activity

Xenotransplantation between discordant species leads to a hyperacute rejection mediated by natural antibodies, both of the IgG and IgM isotypes, activation of complement and endothelial cell activation. The combination of these mechanisms leads to a transplant survival of minutes to a few hours. Polyclonal human immunoglobulins for intravenous use (IVIg) from normal donors have proved effective in a number of antibody-mediated disorders, as well as in inflammatory disorders. We demonstrate that administration of IVIg in a guinea pig to rat model of cardiac xenografting can effectively delay hyperacute rejection. This effect is mediated by the F(ab')2 fragments of IVIg, and is correlated to an anti-complementary activity.

Experimental bilateral lobar lung transplantation and its application in humans

BACKGROUND

The critical lack of donor organs from people of small size or children has created great difficulties in transplantation for recipients who are of smaller size. Surgical techniques of organ reduction and partial transplantation may to some extent solve the problem of disparity in organ size, be it liver or lung, and lessen the problem of scarcity of paediatric organs.

METHODS

In a series of experiments on dogs the surgical technique of pulmonary partition of a large organ from a grown dog followed by transplantation of lobes, either unilaterally or bilaterally, into a young dog was studied. Two series of experiments were performed in two groups of animals; in group 1 transplantation of a single right lobe (n = 6) or single left lobe (n = 6) from a split adult lung was carried out and in group 2 (n = 10) animals received bilateral lobar transplants from a single split adult lung. The animals were sacrificed at fixed intervals (days 8-120 in group 1, days 7-10 in group 2) and the results of the surgical technique were assessed.

RESULTS

Healing of lobar bronchial anastomoses was found to be excellent with no histological evidence of dehiscence or ulceration. There was one bronchial anastomotic stenosis and one arterial thrombosis. Morphological and functional adaptation of the lobes in the thorax was found to be excellent in both groups of animals. The technique has been applied in a clinical setting and the first patient with bilateral lobar lung transplantation followed for 30 months is reported.

CONCLUSION

Lung partition and subsequent lobar transplantation, either unilaterally or bilaterally, is associated with satisfactory early results in an animal experimental model. Initial clinical experience in one patient has been successful.

Study of muscular and ventricular function in dynamic cardiomyoplasty: a ten-year follow-up

BACKGROUND

The basic physiologic principle underlying cardiomyoplasty is long-term electrostimulation of a latissimus dorsi muscle (LDM) wrapped around the heart to obtain a phasic activity that could be integrated with ventricular kinetics. The aim of cardiomyoplasty is to prolong survival and to improve the quality of life of patients with severe chronic and irreversible myocardial failure by improving systolic contraction and correcting diastolic dysfunction.

METHODS

To evaluate the long-term outcome of cardiomyoplasty, we investigated 82 patients electively undergoing this procedure in-our hospital. All patients had severe chronic heart failure that did not respond to optimal medical treatment. Patients had a mean age of 50 +/- 12 years (84% males). The cause of heart failure was ischemic (55%), idiopathic cardiomyopathy (34%), ventricular tumor (6%), and other (5%). The mean follow-up was 4.3 years.

RESULTS

The mean New York Heart Association functional class improved after operation from 3.2 to 1.8. Average radioisotopic left ventricular ejection fraction increased from 17% +/- 6% to 28% +/- 3% (p < 0.05). Stroke volume index increased from 35 +/- 9 to 46 +/- 8 ml/beat/m2 (p < 0.05). The heart size remained stable at long term (evaluated by echo and computed tomography scanning). After cardiomyoplasty the number of successive hospitalizations resulting from congestive heart failure was reduced to 0.4 hospitalizations/patient/year (before operation 2.5, p < 0.05). Computed tomography scans showed at long-term a preserved LDM structure in 82% of patients who underwent operation. Survival probability at 7 years was 54% for the totality of patients, and 66% for patients who underwent operation in New York Heart Association functional class 3. Five patients underwent heart transplantation after cardiomyoplasty (mean delay 29 months), principally as a result of the natural evolution of their underlying heart disease, without major technical difficulties.

CONCLUSIONS

Our 10-year clinical experience demonstrates that cardiomyoplasty increases ejection fraction, improves functional class, and ameliorates quality of life. Ventricular volumes and diameters remain stable long term. LDM structure is maintained long term if electrostimulation is performed avoiding excessive myostimulation. Patient selection is the most important determinant for early and late outcome. Late death in patients undergoing cardiomyoplasty is principally due to sudden death. Our future aim is to incorporate a cardioverter-defibrillator in the cardiomyostimulator, thus improving long-term results. Cardiomyoplasty may delay or prevent end-stage heart failure and the need for heart transplantation.

Early extubation after mitral valve surgery: a target-controlled infusion of propofol and low-dose sufentanil

OBJECTIVE

In the current study, the use of a target-controlled infusion of low-dose propofol was combined with a continuous infusion of sufentanil for patients undergoing mitral valve surgery. The purpose of the study was to evaluate the hemodynamic stability, the time to awakening and spontaneous ventilation, and the feasibility in an early extubation setting of a total intravenous anesthetic technique.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Fifteen patients scheduled for elective mitral valve surgery.

INTERVENTIONS

Induction of anesthesia consisted of sufentanil (1 microgram/kg), propofol (1 microgram/mL) target plasma concentration achieved over 3 minutes, and atracurium (0.5 mg/kg). The propofol target-controlled infusion was maintained at 1 microgram/mL throughout surgery and stopped at skin closure. A continuous infusion of sufentanil at 1.8 micrograms/kg/hr was started after induction and reduced to 0.9 microgram/kg/hr at the start of cardiopulmonary bypass and stopped at the end of bypass. Atracurium was infused at a rate of 0.5 mg/kg/hr up to sternal closure. No inhalation agents were used.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic data were within normal limits. Six patients (40%) responded to verbal commands within 15 minutes postoperatively, 10 (67%) within the first hour, and all patients recovered within 2 hours. Four patients (27%) resumed spontaneous ventilation within the first 15 postoperative minutes. The time to successful spontaneous ventilation was 169 +/- 42 minutes. Spontaneous ventilation was associated with a 21% increase in cardiac index. Total sufentanil dose was 328 +/- 28 micrograms (4.6 +/- 0.2 microgram/kg), whereas total propofol dose was 862 +/- 44 mg (13.1 +/- 1.2 mg/kg). No patient required reintubation.

CONCLUSION

The simplicity of the method with only one change in infusion rate is a major advantage. The technique permits predictable recovery and return to spontaneous ventilation in all patients. Its use in patients entering early extubation protocols is appealing for its reproducibility, simplicity, and safety.

Video-assisted aortofemoral bypass: results in seven cases

Between September 1995 and February 1996 we attempted to perform video-assisted aortofemoral bypass in nine patients. All patients were male with a mean age of 58.7 years, mean weight of 64.7 kg, and mean height of 1.69 m. In two patients it was necessary to switch to open laparotomy due to inadequate aortic exposure in one and extensive aortic calcification in the other. Aortobifemoral bypass was performed by the transperitoneal approach in three patients and unilateral aortofemoral bypass by the retroperitoneal approach in four patients. Exposure was more difficult by the transperitoneal approach. Postoperative graft patency was excellent in all patients. Video-assisted surgery did not shorten the delay to resumption of intestinal transit but it did reduce the duration of hospitalization and need for postoperative analgesia. Our experience suggests that video-assisted aortofemoral bypass without laparotomy can be performed and that it allows more rapid patient recovery.

[2 familial cases of metachromatic leukodystrophy of late onset]

We report here a familial observation of metachromatic leukodystrophy (MLD) in 2 sisters. The very beginning, with only psychiatric manifestations at adolescence, could be precisely established. The evolution towards a dementia, and the evidence of a pyramidal syndrome oriented later towards a clearly organic disease. A very wide bilateral and symmetrical demyelination was shown by Magnetic Resonance imaging. The deficiency in arylsulfatase A activity oriented towards MLD which was confirmed by metachromatic deposits in the nerve biopsy. Molecular biology evidenced in the two, compound heterozygoty with both the classical mutation of the infantile form with loss of a splicing site at the level of intron 2, and the ileu > Ser 179 mutation frequent in adult forms.