[Outcome of 30 congenital atrio-ventricular blocks]. / Devenir à long terme de 30 blocs auriculo-ventriculaires complets congénitaux isolés.

Congenital isolated atrio-ventricular block (CAVB) is a rare pathology, and its management is still rather poorly described through international literature. Within the service of pediatric cardiology leaded by Pr Choussat and Dr Jimenez (Cardiologic Hospital Haut-Lévêque of Bordeaux), we collected from 1980 to 2003, 30 isolated congenital CAVB, constituting the purpose of this retrospective study. Average follow-up is 14 +/- 8.8 years. None death occurred. CAVB are discovered at an average age of 4.8 years old; 6 cases were diagnosed in utero, half of them were associated with maternal lupus. Twenty patients on 30 were fitted with stimulator at an average age of 8.7 +/- 6.9 years old, due to symptoms or bradycardy. Epicardic fitting in VVI mode represents 65% of first approaches, it is followed by endocavitary way for 81% of cases. Cardiac stimulation does not prevent from dilated cardiomyopathy. Among 30 patients 10 were not fitted with stimulator, half of them presents chronotrop insufficiency during effort. As a conclusion, our patients show a good long-term vital prognosis; although CAVB discovered in utero lead to worse prognosis for children.

Immunohistological and ultrastructural analysis of the intimal thickening in coarctation of human aorta.

OBJECTIVES: The histological nature and characteristics of aortic coarctation are not clearly defined, the aim of this study is to analyse intimal thickening in aortic coarctation. METHODS: In order to characterize the components of intimal thickening in coarctation, narrowed segments of aorta obtained after surgery from ten children were examined immunocytochemically and by electron microscopy. RESULTS: Histological analysis of aortic coarctation demonstrated a widened subendothelial region with separation of endothelial cells from the internal elastic lamina. Masson's trichrome staining showed a marked increase in extracellular matrix and cell numbers in the intimal thickening compared with normal aorta. Cellular component analysis demonstrated invagination of the intima by smooth muscle actin-positive cells, with a fragmentation of the internal elastic lamina. No proliferating smooth muscle and inflammatory cells were identified in the intima. In order to characterize the smooth muscle cell phenotypes, various smooth muscle cell markers were sought using specific monoclonal antibodies: alpha-smooth muscle actin, smooth muscle-myosin heavy chain, heavy caldesmon, desmin. In moderate coarcted aorta, at least two distinct smooth muscle phenotypes were identified. In the juxtamedial part of the intima smooth muscle, cells were differentiated and expressed all smooth muscle markers; in the subendothelial part of the intimal thickening, the majority of smooth muscle cells expressed only alpha-smooth muscle actin and appeared dedifferentiated. In regions of marked stenosis, a strong expression of smooth muscle-myosin heavy chain, and heavy caldesmon in the intimal thickening pointed to the presence of redifferentiated smooth muscle cells, not still expressing desmin. Electron microscopic examination also revealed a variety of smooth muscle cell phenotypes in the intimal thickening. In the superficial layer, smooth muscle cells appeared to be in the synthetic state, while in the deeper part, both synthetic and contractile components were identified. CONCLUSIONS: These observations indicated that human coarctation was characterized by intimal recruitment of non-proliferating smooth muscle cells with dedifferentiated phenotype. However, the presence of smooth muscle cells with an intermediate phenotype in the narrowest part of the coarctation suggest that the redifferentiation process could participate in the pathogenesis of aortic coarctation.

Cardiorespiratory response to exercise after venous switch operation for transposition of the great arteries.

STUDY OBJECTIVES: This study reports on the cardiorespiratory response to graded exercise in patients after venous switch operation for transposition of the great arteries. DESIGN: Several small studies have documented a diminished exercise tolerance after Mustard repair for transposition of the great arteries, little information exists, however, about long-term cardiorespiratory exercise performance in patients who have had the Senning procedure. PATIENTS: This prospective study reports on the serial long-term (mean, 11 +/- 2.8 years) cardiopulmonary exercise performance of 43 patients (age, 12 +/- 3.1 years) who underwent a Senning procedure, with no significant postoperative abnormalities. Forty-three matched healthy children were also studied as a control group. MEASUREMENTS AND RESULTS: All underwent exercise testing (Bruce protocol) with metabolic gas exchange to determine parameters at 3 min, anaerobic threshold, similar heart rate (150 beats/min), and peak exercise. Time of exercise was 10.5 +/- 1.9 min in patients and 13.4 +/- 2 min in control subjects (p = 0.0001). Overall, patients reached 73% of peak oxygen uptake achieved by control subjects (32.6 +/- 5.6 vs 44.7 +/- 6 mL/kg/min). Chronotropic response (188 +/- 15.7 vs 166.5 +/- 19.6 beats/min [p = 0.0001]) and oxygen pulse (7.4 +/- 2.9 vs 10.7 +/- 4.2 mL/beat [p = 0.0002]) were lower in patients at peak exercise. Patients had a greater respiratory response to exercise: both respiratory rate and ventilatory equivalent for carbon dioxide were significantly higher at all stages of exercise. Exercise capacity assessed by peak oxygen uptake was correlated with time elapsed since surgical repair (r = 0.48; p = 0.001). CONCLUSIONS: It is concluded that even in asymptomatic patients, exercise endurance and respiratory response are generally altered as much as 11 +/- 2.8 years after venous switch operation, although early surgical repair is predictive of a better long-term functional result.

Repair of tricuspid atresia in 100 patients.

One hundred consecutive patients with situs solitus of the atria and tricuspid atresia have undergone surgical repair since 1968. In patients with ventriculoarterial concordance, a nonvalved Dacron conduit or an aortic valve homograft was interposed between the right atrium and right ventricular outlet chamber. In patients with ventriculoarterial discordance, an aortic valve homograft established continuity between the right atrium and pulmonary artery. Among 73 patients with ventriculoarterial concordance, the hospital mortality rate was 11% (eight deaths), and in 27 patients with ventriculoarterial discordance, it was 15% (four deaths). Before 1974, the year of operation was a significant determinant of hospital mortality (p less than 0.001). Thereafter, the hospital mortality declined and is currently 3.7%. In 82 patients with ages ranging from 4 to 16 years, there were six deaths (7.3%) whereas there were six deaths (33.3%) in 18 patients less than 4 or more than 16 years (p less than 0.001). Mode of ventriculoarterial connection and type of repair did not influence significantly the hospital mortality. There were six late deaths due to infection (two), reoperation (two), heart failure (one), and sudden death (one). Regardless of the mode of ventriculoarterial connection, use of a homograft valve produced better results, i.e., more asymptomatic patients (NYHA Class I) (p = 0.0168) and higher postoperative exercise capacity. Postoperative catheterization data and angiocardiographic measurements in patients with ventriculoarterial concordance demonstrated significant advantages with the interposition of a homograft valve between the right atrium and outlet chamber. Of 82 surviving patients, 94% are in NYHA Class I or II.

Aortic valve homografts in the surgical treatment of complex cardiac malformations.

From April of 1968 to March of 1983, the surgical treatment of complex congenital cardiac malformations requiring an extracardiac conduit for their correction was performed with aortic valve homografts or aortic valved homograft conduits sterilized and preserved in our hospital. Our experience concerns 93 patients in whom a total of 103 aortic valve homografts were implanted. Ages of the patients ranged from 7 months to 36 years (mean 11.6 years). The aortic valve homografts were used from the right atrium to the pulmonary arteries or right ventricle (right atrium-dependent conduit), from the venous ventricle to the pulmonary arteries (ventricle-dependent conduit), or in the pulmonary orifice and in the superior and/or inferior venae cavae. There were 25 early and nine late deaths (36.5%), none of them related to the aortic valve homograft. The clinical follow-up of the 59 survivors (1 month to 15 years, mean 4.3 years) evidenced neither dysfunction of the aortic valve homograft nor thromboembolism or hemolysis; 93% of the patients are in New York Heart Association Class I or II. Control cardiac catheterization in 53 patients evidenced a pressure gradient in only 14 ventricle-dependent conduits. In seven patients with serial control catheterizations after 5 to 10 years, the pressure gradient had not increased.

Isolated ventricular inversion with situs solitus: successful surgical repair.

A 7-month-old infant with ventricular inversion without transposition of the great arteries in situs solitus, associated with a ventricular septal defect, is reported. When the infant was 13 months of age, successful surgical repair was undertaken by performing an intraatrial transposition of venous return using the Senning procedure and by closing the ventricular septal defect with a patch. The postoperative course was uneventful except for a well-tolerated complete heart block. No systemic valve incompetence appeared during the 53 months of actual follow-up. A complete review of the literature suggests that this is the sixth reported instance of successful repair. Injury of the abnormally located conduction tissue is regarded as the most threatening complication.

Isolation of the right subclavian artery.

Loss of continuity between subclavian artery and aorta with persistent connection to the homolateral pulmonary artery through a ductus arteriosus is an uncommon malformation, involving generally the left subclavian artery and associated with intracardiac or aortic arch anomalies. We report a case of right subclavian isolation with a left-sided aortic arch, presenting as a single anomaly and surgically corrected by aortic reimplantation.

Exclusive double outlet right ventricle with atrioventricular concordance and pulmonary stenosis. Results of reconstructive surgery.

Double outlet right ventricle associated with atrioventricular concordance, pulmonary stenosis and situs solitus of the atria is a subset of double outlet right ventricle related through the surgical treatment. From 1974 to 1985, 14 patients, 5 males, 9 females (mean age 8.9 years, range 13 months-22 years) were operated upon. All patients had infundibular stenosis and normal or large pulmonary arteries. The apex of the heart was to the right in 2 patients, the right and left ventricles were superior and inferior in 2 patients and 1 patient had both anomalies. The ventricular septal defect was subaortic in 11 patients (aorto-mitral discontinuity in 5) and non-committed in 3 patients. Three patients had 2 ventricular septal defects. The aorta was anterior in 3 patients and to the right of the pulmonary artery in 11 patients. All patients, through a transventricular and transatrial approach, had a reconstructive surgery. In 3 patients, an aortic homograft valved conduit was used. One patient had the ventricular septal defect enlarged. There was one early death (7.1%) from high residual right ventricle pressure and no late death. One patient had a transient atrioventricular block. One patient was reoperated upon for a residual ventricular septal defect. All survivors had a good clinical result. Re-evaluation in 8 patients confirmed excellent haemodynamics: the right ventricle to pulmonary artery pressure gradient decreased from 80 mm Hg (range 60-95) preoperatively to 24 mm Hg (range 3-32) postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

The short- and mid-term results of bidirectional cavopulmonary shunt with additional source of pulmonary blood flow as definitive palliation for the functional single ventricular heart.

OBJECTIVE: The purpose of this study was to demonstrate the early and late outcomes of bidirectional cavopulmonary shunt (BCPS) as a definitive procedure for the functional single ventricular heart. METHOD: From September 1991 to December 1997, 34 patients underwent a BCPS procedure without a routine conversion to Fontan circulation. The additional source of pulmonary blood flow was left in all patients. Conversion was performed only when it was required for excessive cyanosis. RESULTS: The hospital mortality rate was 8.8% (3/34, 95% confidence limit; 1.9-23%) and the 5-year survival rate was 75% for a mean follow-up period of 33+/-22 months. Seven patients underwent a conversion procedure for remnant or recurrent cyanosis and deterioration of exercise tolerance. Four of these patients died after conversion to Fontan circulation. Twenty-five long-term survivors with BCPSs maintained an arterial oxygen saturation of 84+/-6.1%, and 52% of them had a normal exercise tolerance or mild limitation. No patients developed severe late complications other than recurrent cyanosis. CONCLUSION: Due to the high mortality after conversion to Fontan circulation in patients whose conditions had deteriorated, we could not demonstrate the clear superiority of long-term BCPS over the construction of Fontan circulation for management of the functional single ventricular heart. If deteriorated conditions were successfully managed in the late period, the outcome of long-term BCPS would have been better.

Clinical characteristics affecting success or failure of PTCA in patients with multiple vessel disease and poor candidates for surgery.

A special form of complex coronary angioplasty is represented by the extension of indications for percutaneous transluminal coronary angioplasty (PTCA) to patients with multivessel disease (MVD) for whom surgery is not indicated, and thus for whom surgical standby is not available. Over a two-year period, 254 consecutive coronary patients with multivessel disease underwent PTCA under such conditions. These patients could not benefit from surgery for various reasons. Of the 612 arteries involved, 155 were occluded, 47 had been previously bypassed. A distal nonbypassable lesion in one of the three major arteries was found in 244 patients, 61 had suffered from a previous infarct, 24 demonstrated an ejection fraction below 0.40, and in 19 a single patent vessel was found. Fifteen patients were in cardiogenic shock and 69 procedures were undertaken for unstable angina. Of this latter group, 25 emergency PTCA were attempted for refractory unstable angina, and 44 additional emergency procedures were directed to the treatment of acute infarct. A total of 40 intra-aortic counterpulsations were needed. As far as possible the procedure aimed at full revascularization. Immediate outcome is strongly affected by the clinical context, and despite a rather constant initial success rate (88-95%), the procedural mortality (directly related or not) can change dramatically with clinical factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Radionuclide angiocardiography in the diagnosis of congenitally corrected transposition of the great arteries.

Congenitally corrected transposition of the great arteries (CTGA) may constitute a pitfall for interpretation of radionuclide angiocardiography, since the two anatomic discordances cancel each other from a physiologic point of view. However, the unusual shape of the ventricles (due to ventricular discordance) and the relative position of the great arteries (due to transposition) can allow a clear scintigraphic diagnosis, especially for CTGA with mild or absent associated congenital anomalies. Five cases are described. Gated cardiac blood pool imaging is particularly helpful since it permits multiple views, allowing a more detailed study of the scintigraphic signs.

[The best of pediatric cardiology in 2002]. / L'essentiel de 2002 en cardiologie pédiatrique.

This past year has been remarkable for considerable advance in the field of interventional cardiology for congenital heart disease. Ostium secundum atrial defect is by now cured by percutaneous closure with excellent results. Closure of patent foramen ovale (PFO) in patients with paradoxical embolism is still controversial. Nevertheless, some studies demonstrate the efficiency of this procedure, reducing the incidence of ischemic events. In cases of platypnoea-orthodeoxia syndrome occurring in patients having undergone pneumonectomy or presenting dilatation of ascending aorta, closure of PFO with an occluder gives spectacular results with disappearance of dyspnea and cyanosis. Other more complex procedures such as closure of membranous ventricular septal defect, replacement of an pulmonary or aortic valve are still to be assessed. As the last point let us underline the progress of foetal cardiology, the studies of sudden death in children an adolescents, and the care of adults with congenital heart disease.

[The best of 2001. Pediatric cardiology]. / L'essentiel de 2001 en cardiologie pédiatrique.

During this last year, paediatric cardiology has gone through significant changes, although no capital evolution is to be pointed out. Foetal cardiology, initiated some years ago has been remarkably developed. The rate of cardiac anomalies detected is increasing, which leads to very difficult discussions regarding therapeutic abortion and even increasing legal responsibility as evidenced by "arrêt Perruche". Interventional cardiology is more and more resorted to and a reliable, safe and efficient procedure which improved atrial septal defect (ASD) occlusion devices. Data on occlusion of ASD and patent foramen ovale confirm the reliability of these methods. In the field of imaging. Nuclear Magnetic Resonance angiography which gadolinium can, in some cases, replace fluoroscopy with clearer pictures. Reinforced interest is given to Primary Pulmonary Hypertension (PPH) due to genetic studies and new therapies. The rate of familial PPH is about 6%. It is an autosomic dominant disorder located on chromosome 2q31-32. New treatment use various prostacyclines administrated by different ways: subcutaneously, orally or by inhalation. It is too early to assess their impact on the prognosis. Finally, we may note the paradoxical importance of congenital heart disease in adult as an outcome of interventional cardiology and follow-up of operated children becoming adults. As the beginning of the 21st century, the definition of paediatric cardiology has considerably evolved.

[Value of fetal echocardiography in screening for congenital heart diseases. Report of 1,049 consecutive examinations]. / Intérêt de l'échographie cardiaque foetale dans le dépistage des cardiopathies congénitales. A propos de 1,049 examens consécutifs.

Specialised antenatal echocardiographic screening has allowed 1049 consecutive examinations in 992 patients resident in the Aquitaine region over a period of nine years. The most frequently encountered indications are expertise (suspicion of cardiopathy during initial screening) and family history. Expertise allows a higher detection rate (46.5%) compared to the other indications. We have screened 150 cardiopathies in utero and among them 143 were able to followed up after delivery. We have noticed a much greater severity of the anomalies compared to those encountered in paediatric cardiology. An associated chromosomal anomaly was noticed in 9% of cases and more frequently for atrio-ventricular communication and conotruncal cardiopathies. The rate of abortion was 35%, and the mortality for the surviving pregnancies was elevated (35%). Pharmacological treatment was instituted in 95% of cases of sustained supraventricular tachycardia with 81% successful. Diagnosis errors concerned benign cardiopathies above all and did not change the management of the pregnancy. The sensitivity of fetal echocardiography was 93.1% and its specificity 99.1%. This study shows the viability of fetal cardiac echography for the detection of the majority of congenital cardiopathies in a population at risk and in the management of fetal cardiac rhythm disorders. Nevertheless it remains a specialised examination for which the performance depends much on the initial screening performed by gynaecologists. Although the mortality rate of the screened children is elevated, indicating the frequent parental choice of abortion and the complexities of the cardiopathies, antenatal diagnosis has allowed optimisation of the neonatal management for certain curable cardiopathies.

[Adaptation of left ventricular performance to isometric stress]. / Adaptation de la performance ventriculaire gauche à un effort isométrique

The authors report the haemodynamic changes observed during isometric stress corresponding to 30% of the maximum isometric effort, sustained for 3 minutes, in 22 normal subjects and 12 patients with cardiomyopathy. Echocardiographic study of the left ventricular diameters of 10 cardiac patients completes the work. The heart rate in normal subjects during effort increases by 45 +/- 30%, and the flow by 30 +/- 24%. The blood pressure is raised by +/- 25 +/- 8 mmHg, without significant change in the left ventricular end-diastolic pressure (less than +4 mmHg), or in peripheral resistance. The external work of the left ventricle increases by 75 +/- 41%, demonstrating an increase in the inotropic state of the myocardium. Max. vec. and the various indices of contractility are increased on average by +8.29 +/- 4.55 28 c/s. Adaptation to the increased pressure brings into play only the contractile reserve of the myocardium.

[Left ventricular function of the coronary patient: relation between ventricular kinetic disorders and alterations of myocardial contractility]. / La fonction ventricularire gauche du coronarien: Relations entre les troubles de la cinétique ventriculaire et les altérations de la contractilité myocardique

The left ventricular kinaetics of 29 coronary patients (pure angina and with sequela of myocardial infarction) was studies by biplane angiocardiography. Their contractility was assessed by measurement of the Vmax and VECmax indices derived from the relationship between contractile elements shortening speed-overall wall tension, in isovolumetric phase. An excellent relationship links the hypokinaetic area with decrease of the ejection fraction (SV/LSV): when the hypokinaetic area exceeded 20% of the overall endocardial surface, the ejection fraction deveased below 0.40, and signs of cardiac failure were manifest. Pure anginal patients at rest kept normal kinaetics, late diastolic volume, ejection fraction and myocardial mass. A myocardial hypertrophy develops in the areas adjacent to the fibrous scar. In some cases (group I) it compensates for the ventricular dysfunction; in other cases, it is not sufficient to compensate for the ejection fraction reduction. One must then admit the presence of diminished contractility in the areas adjacent to the fibrous scar, as is suggested by the increase of the late diastolic pressure, the decrease of the externel work of the left ventricle and of the contractility indices. Analysis of both the natural and post-operative courses in these patients shows that Vmax the ejection fraction and the hypokinaetic areas afford excellent criteria for prognosis and operability.

[Hemodynamic effects of intravenous amiodarone in humans]. / Action hémodynamique de l'amiodarone intra-veineuse chez l'homme

The haemodynamic action of I-V Cordarone have been studied in 20 subjects over a 15 minute period. Over the 15 minute period we studied variations in left pulmonary and ventricular pressures, in cardiac output, and in the paramaters of contraction VEC max, V max and Taylor's index. At a dose of 5 mg/kg there is a fall in peripheral resistance (1274 +/- 232 to 915 dynes/s/cm-5), and the measurements of contraction hardly vary. At a dose of 10 mg/kg, after an initial increase in output and a fall in peripheral resistance there occurs, after 4 minutes, an increase in left ventricular end-diastolic pressure (from 6 +/- 2 to 13 +/- 4 mmHg, P less than 0.01), and a lowering of contractility (VEC max reduced from 49.7 +/- 12.4 to 27.1 +/- 3.8, P less than 0.001). We have shown that the first phase of this response is due to the solvent (Tween 80), while the fall in contractility is due to the amiodarone. Doses above 10 mg/kg must be used with care, and only if there is no evidence of impaired cardiac function.

[Fulguration of accessory pathways in children. Value of two-dimensional echocardiography]. / Fulguration des voies accessoires chez l'enfant. Intérêt de l'échocardiographie bidimensionnelle.

Six children (4 boys and 2 girls) aged from 3 to 7 years who had an accessory pathway and were suffering from paroxysmal (n = 4) or permanent (n = 2) refractory reciprocating tachycardia underwent transcatheter ablation of the accessory pathway alone in 5 cases and of the normal and accessory pathways in 1 case. Conduction in the accessory pathway was interrupted in 3 cases and sufficiently modified in 2 cases for the attacks of tachycardia to be suppressed by a simple and previously ineffective medical treatment. There was one failure. The authors underline the value of two-dimensional echocardiography in such cases. This technique is useful in the preoperative evaluation, during catheter insertion, and also in the choice of the electrodes to be used, for the ablation itself and in the search for postoperative lesions. Transcatheter ablation seems to be feasible and safe enough to be offered as an alternative to surgery in the treatment of refractory reciprocating tachycardia in children.

[Factors predictive of mortality in Ebstein's anomaly]. / Facteurs prédictifs de mortalité dans la maladie d'Ebstein.

Nearly 150 years after the description of Ebstein's anomaly the prognostic factors are not well known. Besides the foetal and neonatal forms which carry a poor prognosis the adult forms are often well tolerated and pose the difficult problem of management. This was a retrospective study of 73 patients with this malformation followed up between 1967 and 2002 at the University Hospital of Bordeaux. There were 14 deaths (19%) half of which (7) occurred during the first 3 months of life. The factors predictive of mortality (p<0.05) were: age, associated malformations, Classes III-IV of the New York Heart Association, cardiac failure, malaises, cyanosis, a raised cardiothoracic index, and a high mitro-tricuspid displacement indexed to body surface area. Supraventricular arrhythmia and the Wolff-Parkinson-White syndome do not seem to be associated with extramortality. Surgery, with reference to published studies, seems to improve survival, functional status and decrease the prevalence of arrhythmias. It would appear to be justified to propose surgery when functional status declines or when signs of poor prognosis are observed.

[Prosthetic valve thrombosis in pregnancy. A single-center study of 12 cases]. / Thromboses de prothèses valvulaires cardiaques chez la femme enceinte.

Pregnancy in women with mechanical prosthetic heart valves carried an increased risk of thromboembolic complications due to changes in haemostasis. Prosthetic valve thrombosis is a serious complication resulting in high mortality. Ten patients from 20 to 38 years of age had 12 thromboses of mechanical heart prostheses during pregnancy. The prosthesis was mitral in 8 cases and aortic in 4 cases. The prosthesis was a ball valve in 1 case, a tilting disc in 3 cases and bi-leaflet in 8 cases. Initial emergency treatment was surgical in 3 cases and medical in 9 cases (thrombolysis in 7 cases and simple heparin therapy in 2 cases). Secondary surgery was carried out in one patient after failure of heparin therapy. There was one death in the surgical group (4 cases, 25%) and 30% foetal mortality in the surviving women. In the thrombolysis group (7 cases), two women died (28%) after failure of treatment. Both patients had mitral valve prostheses and were in cardiogenic shock. Three women, of the other 5 thrombolysed cases, were able to complete their pregnancies and had healthy babies with no foetal mortality. No per-thrombolytic embolic complications were observed. However, there was one severe bleeding complication which was successfully managed by surgical drainage. Finally, a global success rate of 75% (9 out of 12 patients) and a mortality of 30% (3 maternal deaths in the 10 patients--all with mitral valve protheses) were observed irrespective of the therapeutic protocol used. Thrombosis is the most life-threatening complication for women with prosthetic heart valve during pregnancy. Emergency surgery for valve replacement or thrombectomy is the commonest treatment. Trombolysis is classically limited by the risk of haemorrhagic and thromboembolic complications reported in the literature. In this study, thrombolysis was effective in the 71% of cases with a low risk of haemorrhagic complications.