Utilidad de las fístulas arteriovenosas autólogas para hemodiálisis en pacientes diabéticos / Value of autologous arteriovenous fistulae for haemodialysis in diabetic patients

Objetivo. Evaluar la permeabilidad de las fístulas arteriovenosas (FAV) para hemodiálisis realizadas en nuestro servicio, con la comparación de los resultados en pacientes diabéticos y no diabéticos. Pacientes y métodos. Análisis retrospectivo de 273 FAV autólogas realizadas en 222 pacientes, durante tres años (1998-2000). De estos 222 pacientes, 73 (32,9 per cent) eran diabéticos, y 149 (67,1 per cent), no diabéticos. Se realizaron un total de 138 FAV radiocefálicas (50,5 per cent) -48 en diabéticos y 90 en no diabéticos- y 135 FAV humerocefálicas (49,5 per cent) -43 en diabéticos y 92 en no diabéticos-. Al 20,3 per cent de los pacientes se les realizó más de una FAV. Se aplicó análisis estadístico univariante y multivariante mediante regresión de Cox y cálculo de probabilidad por Kaplan-Meier. Resultados. El seguimiento medio fue de 12 meses (intervalo, 136). La permeabilidad global primaria al año y a los dos años fue de 65 y 58 per cent, respectivamente. Los pacientes diabéticos tienen una permeabilidad al año y a los dos años del 60 y 40 per cent, respectivamente, frente a un 73 y 62 per cent, respectivamente, de los no diabéticos, pero en el seguimiento tardío los diabéticos tienen una mayor probabilidad de trombosis frente a los no diabéticos -odds-ratio, 1,49 (0,97-2,3)-. No hubo diferencias de permeabilidad al año entre FAV radiocefálicas y humerocefálicas. Ninguno de los factores analizados tuvo significación estadística en la permeabilidad. Conclusiones. La diabetes actúa de factor de riesgo en la permeabilidad de las fístulas a largo plazo. No hay diferencias estadísticamente significativas según el lugar de realización de las FAV (AU)

New-generation valved conduit: an experimental study.

OBJECTIVE: An ideal valved conduit to repair complex congenital heart defects is yet to be developed. In this study we have evaluated the merits of our newly developed calcification-free biologic valve incorporated in a compatible conduit of biologic origin in an animal model. METHODS: Porcine aortic valves and main pulmonary arteries were cross-linked in glutaraldehyde, followed by coupling to partially degraded heparin through an intermediate surface-bound substrate containing amino groups. Because commercially available valves are treated only with glutaraldehyde, control aortic valves and main pulmonary arteries were cross-linked in 0.625% glutaraldehyde. Valved conduits were fabricated from main pulmonary arteries, which were sewn to the aortic and ventricular ends of aortic valves. Valved conduits were examined for calcification and other pathologic changes after being implanted in the descending thoracic aorta in juvenile sheep for 5 months. RESULTS: Severe calcification was noticed in all layers of cusps (calcium, 231.86 +/- 17.90 mg/gm) and aortic wall (calcium, 123.24 +/- 24.72 mg/gm) of aortic valves and main pulmonary arteries (calcium, 135.43 +/- 26.63 mg/gm) of valved conduits treated with 0.625% glutaraldehyde. Cusps (calcium, 1.28 +/- 0.22 mg/gm) of the aortic valve of heparin-bonded conduits did not calcify at all. Only sparse calcific deposits were noticed in the medial layer of the aortic wall (calcium, 25.90 +/- 22.79 mg/gm) of aortic valves and main pulmonary arteries (calcium, 9.64 +/- 10.79 mg/gm) of the valved conduits coupled to heparin. CONCLUSION: Heparin coupling is effective in preventing calcification of glutaraldehyde cross-linked valved conduits implanted in the systemic circulation of juvenile sheep.

Single-institution effectiveness assessment of open-heart surgery in octogenarians.

OBJECTIVE: To determine short- and long-term outcome of open-heart surgery in octogenarians. METHODS: We reviewed the medical charts of 130 consecutive octogenarians undergoing open-heart surgery. Patients with significant comorbidity were excluded from the study. The effect of cardiac and operative risk factors on mortality and morbidity was evaluated. General practitioners and cardiologists were contacted in order to obtain information on the patients' current medical and functional status. RESULTS: Operative mortality for valve replacement (VR) and coronary artery bypass grafting (CABG) was 11.5%. Four-year survival was 73.5% with 75.9% still living independently. The relative risk for operative mortality was 4.3 in case of extracorporeal bypass time exceeding 95 min and 3.6 in case of significant left main stem disease. The risk of late death increased 2.5 times at a left ventricular ejection fraction lower than 50%. CONCLUSIONS: Our data match the results of similar studies involving large numbers of patients. When a multicenter data bank is missing, the evaluation of a relatively small patient group can yield information that may be as useful to patient and physician as information obtained by large studies. Open-heart surgery in octogenarians carries an acceptable mortality risk and its effectiveness in terms of improved quality of life is good.

Mitral valve repair-related hemolysis: a report of two cases.

Two patients are described who suffered from progressive intravascular hemolysis following different kinds of reconstructive surgery of the mitral valve. Within the context of increasing numbers of operations aimed to preserve the mitral valve, the importance and difficulty of prompt recognition and adequate treatment of this very uncommon but potential lethal complication are emphasised.

Single access for minimally invasive aortic valve replacement.

BACKGROUND: The method of replacing the aortic valve via a minithoracotomy has been reported in the recent literature. Although this strategy has clear advantages, further refinements of the process make the procedure even less invasive. METHODS: Aortic valve replacement was performed in 27 patients via a right parasternal minithoracotomy without rib resection. Cardiopulmonary bypass was connected through the same access site. Standard surgical technique and equipment were employed. RESULTS: There were no intraoperative complications. All patients survived and could be discharged home within 1 week, except 1. Cardiopulmonary bypass time, aortic cross-clamp time, and total operating time averaged 114 +/- 26, 76 +/- 19, and 190 +/- 40 minutes, respectively. Three patients could be extubated in the operative theater, the others in the intensive care unit at an average of 10 +/- 7 hours postoperatively. Chest drainage lost averaged 430 +/- 380 mL. CONCLUSIONS: The advantages of this method include further reduction of surgical trauma, early mobilization, and rehabilitation of the patient. Surgical technical improvements include avoidance of groin cannulation, simpler equipment, safe venting of the left ventricle, and preservation of chest wall integrity.

Improved regional left ventricular performance in mitral valve replacement with orthotopic refixation of the anterior mitral leaflet.

BACKGROUND AND AIMS OF THE STUDY: To investigate the influence of different surgical techniques of chordal preservation in mitral valve replacement (MVR) on left ventricular size and function, we studied a series of 244 patients who underwent mitral valve replacement either with (n = 161) or without (n = 83) preservation of the subvalvular structures. RESULTS: Preoperatively there were no differences between the two patient groups. Three months postoperatively, echocardiography demonstrated that chordal preservation in MVR resulted in smaller left ventricular end-systolic diameter (LVESD) and end-diastolic diameter (LVEDD): preservation versus resection, LVESD: 43.4 +/- 7.8 mm versus 48.8 +/- 9.2 mm (p < 0.05), LVEDD: 57.3 +/- 7.8 mm versus 62.9 +/- 10.5 mm (p < 0.05) and a significantly decreased LV-L (long axis) (87.1 +/- 4.2 mm versus 97.5 +/- 5.7 mm; p < 0.05). There was no significant difference in cardiac dimensions between the three patient subgroups in whom chordal preservation was possible. In addition, left ventricular ejection fraction in the preservation groups was significantly improved compared with the resection group (54.2 +/- 11.2% versus 48.1 +/- 12.4%, p < 0.05); there were no differences between the preservation subgroups. Regional wall motion analysis revealed significantly improved segmental myocardial performance in all segments if both leaflets were preserved or the anterior mitral leaflet was reattached to the anterior mitral annulus.

Porcine mitral stentless valve mid-term clinical results.

OBJECTIVES: Time testing is essential with any valvular procedure, especially when a new concept is introduced such as the mitral stentless valve. Our purpose is to evaluate the results obtained over 4 years with this operation, particularly to attest the impact of preservation of annulo ventricular continuity on the long term results of these patients. METHODS: From March 1992 to August 1996, 120 patients had their mitral valves replaced with a porcine stentless mitral valve. The observation period was 54 months with total patients follow-up of 3424 months with a mean of 28.5 months. The age ranged from 11 to 72 years (mean 35.22 +/- 14.98). There were 73 females (60.8%) and 47 males (39.2%). The predominant etiology was rheumatic heart disease. Associated procedures were performed in 12 patients (10%), and the great majority of the patients were in functional class III and IV (NYHA). RESULTS: Hospital mortality occurred in seven patients (5.83%) non valve related except for one early case of endocarditis. Early reoperation related to technical failure were necessary in 4 patients without mortality. Follow-up was accomplished in 101 patients and ranged from 2 to 54 months. Late reoperations were required in 16 patients (nine due to mitral insufficiency, five because of endocarditis and two for mitral stenosis). Most reoperations were related to technical failure. Among the 82 patients presently in control, 72 showed a competent mitral stentless valve, eight with stable mild mitral regurgitation and in two a decreased mitral orifice. Hemodynamic performance of the valve has been excellent in this group, particularly in patients with left ventricular dysfunction. CONCLUSION: Although technical complexity remains the main cause of reoperations with this valve, experience has shown that it not only provides preservation of the left ventricular function but also promised significant increase of the ejection fraction in patients with poor left ventricular function.

Left ventricular remodelling and improvement in Freestyle stentless valve haemodynamics.

OBJECTIVE: To assess how left ventricular (LV) hypertrophy, geometry and function change after stentless aortic valve replacement for aortic stenosis, and to elucidate the physiological mechanism of the improvement in stentless valve haemodynamics. METHODS: 81 patients with aortic stenosis (age 75 +/- 6 years, 47 male) underwent aortic valve replacement (plus CABG in 33 patients) with a Freestyle stentless porcine valve (mean size 23 +/- 2 mm). They were prospectively investigated by Doppler echocardiography at 2 weeks, 3-6, 12, and 24 months after operation. Two hundred and forty-six echocardiograms were obtained and analysed. Aortic valve performance was assessed from its effective orifice area (EOA), the transvalvular increase in mean flow velocity (delta mV), the deceleration time of aortic flow velocity, and mean pressure drop (mPG). LV hypertrophy was assessed from LV mass index; LV geometry, from the ratio of wall thickness to the radius (T/R ratio) and LV function, from stroke volume index (LVSVI) and myocardial stroke work (SW). RESULTS: By 2 years after operation, LV mass index had fallen from 162 +/- 64 to 109 +/- 36, g/m2, and T/R ratio from 0.61 +/- 0.25 to 0.43 +/- 0.10. LVSVI increased from 29.4 +/- 10 to 42 +/- 17, ml/m2, and myocardial SW from 3.1 +/- 1.6 to 5.2 +/- 2.2, mJ/cm3 (all P < 0.001 by ANOVA), while LV outflow tract diameter remained unchanged. At the same time, stentless valve EOA increased from 1.59 +/- 0.75 to 2.2 +/- 0.72, cm2, and delta mV (from 82 +/- 31 to 49 +/- 24, cm/s) and mPG (from 9.7 +/- 5.0 to 5.2 +/- 3.7 mmHg) both fell significantly (all P < 0.001 by ANOVA): as the deceleration time of aortic flow velocity increased from 153.6 +/- 64.1 to 202.7 +/- 37.6 ms (P < 0.001 by ANOVA). CONCLUSION: After stentless aortic valve replacement, LV mass index and wall thickness both fall towards normal, and myocardial stroke work increases. These ventricular remodelling processes are accompanied by a more physiological flow jet at valve cusp level, which permits a greater stroke volume to be ejected with a smaller transvavular velocity increase, so that effective orifice area increases.

Minimally invasive mitral valve replacement: port-access technique, feasibility, and myocardial functional preservation.

OBJECTIVE: This experiment examined the feasibility of minimally invasive port-access mitral valve replacement via a 2.5 cm incision. METHODS: The study evaluated valvular performance and myocardial functional recovery in six mongrel dogs after port-access mitral valve replacement with a St. Jude Medical prosthesis (St. Jude Medical, Inc., St. Paul, Minn.). Femoro-femoral cardiopulmonary bypass and a balloon catheter system for myocardial protection with cardioplegic arrest (Heartport, Inc., Redwood City, Calif.) were used. The mitral valve was replaced through a 2.5 cm port in the left side of the chest, and the animals were weaned from bypass. Cardiac function was measured before and at 30 and 60 minutes after bypass. Left ventricular pressure and electrical conductance volume were used to calculate changes in load-independent indexes of ventricular function. RESULTS: Each procedure was successfully completed. Recovery of left ventricular function was excellent at 30 and 60 minutes after bypass compared with the prebypass values for elastance (30 minutes = 4.04 +/- 0.97 and 60 minutes = 4.27 +/- 0.57 vs prebypass = 4.45 +/- 0.96; p = 0.51) and for preload recruitable stroke work (30 minutes = 76.23 +/- 4.80 and 60 minutes = 71.21 +/- 2.99 vs prebypass = 71.23 +/- 3.75; p = 0.45). Preload recruitable work area remained at 96% and 85% of baseline at 30 and 60 minutes (p = not significant). In addition, transesophageal echocardiography demonstrated normal prosthetic valve function, as well as normal regional and global ventricular wall motion. Autopsy revealed secure annular-sewing apposition and normal leaflet motion. CONCLUSIONS: These results suggest that minimally invasive mitral valve replacement using percutaneous cardiopulmonary bypass with cardioplegic arrest is technically reproducible, achieves normal valve placement, and results in complete cardiac functional recovery. Minimally invasive mitral valve replacement is now feasible, and clinical trials are indicated.

Mitral valve replacement with total preservation of native valve and subvalvular apparatus.

BACKGROUND AND AIMS OF THE STUDY: Preservation of the mitral valve and subvalvular apparatus was introduced clinically in the early 1960s, but for two decades the technique for mitral valve replacement included excision of both leaflets and their attached chordae tendineae. Lately, emphasis has been replaced on retaining the mitral subvalvular apparatus during valve replacement because of its role in left ventricular function. Hence, during the past six years, when performing mitral valve replacement we have, when possible, preserved the valvular and sub-valvular mitral apparatus. METHODS: Between January 1990 and November 1996, complete retention of all mitral tissue in connection with mitral valve replacement was performed in 58 patients (23 women and 35 men). Mean age was 63 years (range: 23 years to 77 years). Coronary bypass was a concomitant procedure in 19 patients; both the mitral and aortic valve was replaced in four cases. Calcified and/or stenotic valves were not a contraindication for the procedure; calcified plaques were removed. Adhesion between anterior and posterior leaflets was treated with sharp dissection. Valve and subvalvular tissue were preserved. The leaflets were reefed within the valve-sutures and compressed between the sewing ring and the native annulus when implanting the valve prosthesis. Chordal tension on the ventricle is thus maintained and the chordae pulled away from the valve effluent. RESULTS: Six patients died in the postoperative period and three had transient neurological symptoms. In no patient was death or transient neurological symptoms a consequence of the retention of mitral leaflets with subvalvular apparatus. CONCLUSIONS: We find the described technique to be useful not only in valve insufficiency but also in valve stenosis when preserving the mitral leaflets with sub-valvular apparatus during valve replacement. The technique is without procedure-related complications and prevents obstruction of left ventricular outflow tract.

[Simultaneous tricuspid valve operation in patients undergoing aortic and mitral double valve replacement].

In triple valvular surgery, AVR+MVR+TVR or TVP, there are some problems around operation, because patients impaired cardiac function after a long history of the disease and some of them are reoperation cases. The sixty-five patients operated from May in 1980 to June in 1993 were examined. They were divided into two groups, group P and group R, depending upon procedure of tricuspid position. Group P consisted of 51 patients and group R of 14 patients. There were 22 (34%) reoperations. In group P, organic changes in tricuspid valve were mild, however in group R, there were commissural fusion in 8 patients, destruction of leaflet due to infectious endocarditis in one patient, and marked tricuspid annular dilatation in five patients. There was one early death in group R, no early death in group P. Actuarial survival rate at the 10th postoperative year was good as 81.6% in group P and 85.7% in group R. There were no significant differences in operative mortality and actuarial survival between group P and R.

[Long-term clinical results with a new surgical method for the fragile valvular annulus].

We performed prosthetic valve replacement with skirt in 11 patients for the fragile valvular annulus. Subjects included 6 patients with active infective endocarditis involving aortic root abscess, 2 patients with systemic disease requiring steroid treatment, and 3 patients with hemolysis or perivalvular leakage. Operative procedure in 11 patients was performed aortic valve replacement with Dacron or Xenomedica skirt attached to the prosthetic ring. One patient died of heart failure during perioperative period. 2 patients died of arrhythmia, heart failure in late postoperative period. The event free rate was 77.1% since 5 years after operation. We conclude that prosthetic valve replacement with skirt is useful to tha fragile valvular annulus.

Wear patterns in the Sorin Bicarbon mechanical heart valve: a clinical explant study.

BACKGROUND AND AIMS OF THE STUDY: Mechanical heart valve prostheses are subject to wear due to impact and friction between the occluder(s) and valve housing. Reference data on the extent of wear in vivo is lacking. Therefore, the aim of this study was to describe the wear pattern in Sorin Bicarbon valves explanted from humans for comparison with the findings established in an earlier in vitro study. METHODS: We investigated eight valves explanted from seven patients, which had been functioning for more than six months and were returned to the Sorin Company for investigation. The protocol comprised: (i) initial visual inspection on receipt; (ii) stereomicroscopy after cleaning and disassembly; (iii) computed planimetry of the worn areas in the housing; (iv) pivot surface profilometry; and (v) scanning electron microscopy. RESULTS: All wear depths and exposed areas of titanium were less than that predicted from in vitro figures. No valves were explanted due to mechanical failure and none of the patients had reported peripheral embolic events which could be attributed to valve wear. The extent of wear was comparable with that of other valves. CONCLUSIONS: This descriptive study did not indicate any association between the Bicarbon valve wear characteristics and clinical complications. Clinical studies on valve performance are of paramount importance for elucidating this issue. The establishment of an independent body for studying explanted valves in collaboration with the manufacturers may promote the publication of findings which are of interest for the entire medical community.

Hemodynamic characterization of the CarboMedics mitral valve prosthesis.

BACKGROUND AND AIMS OF THE STUDY: The hemodynamic function of the CarboMedics bileaflet mitral valve prosthesis was evaluated by Doppler echocardiography and by heart catheterization. The clinical state of the invasively examined patients was evaluated before and after surgery. METHODS: Doppler echocardiography was performed in 54 patients at six months after surgery. Further, combined right and left heart catheterization was performed in 22 of these patients before surgery and at six months thereafter. RESULTS: The Doppler mean gradients were small (3.6 +/- 1.2 mmHg), and corresponded well with Doppler mean gradients in the subgroup examined with both methods (3.5 +/- 1.1 mmHg) and with the invasive gradients (3.4 +/- 1.9 mmHg); there was also no difference between the different valve sizes. Clinically, pressure recovery distal to the valve is probably so small that no systematic difference between the two techniques of measurement is present. Only physiological regurgitation was found, and no case of valve dysfunction. The patients improved from functional NYHA class 3.1 +/- 0.4 to 1.4 +/- 0.6, regardless of preoperative diagnosis, with most pronounced improvement in those with mitral stenosis. Pulmonary artery pressure was normalized. Pulmonary vascular resistance and cardiac index improved slightly. CONCLUSIONS: In conclusion, the valvular prostheses demonstrated excellent hemodynamic function. There was striking agreement between the small invasive and non-invasive gradients. Finally, the functional status of the patients improved considerably, most distinctly in those patients with prior mitral stenosis.

Hemodynamics of St. Jude Medical prostheses in the small aortic root: in vivo studies using dobutamine Doppler echocardiography.

BACKGROUND AND AIMS OF THE STUDY: The well known correlation between prosthetic valve orifice area and transvalvular pressure drop has raised concerns about the presence of significant residual gradients when only a small-sized prosthesis can be implanted, particularly in patients with a large body surface area. The aim of this study was to study the hemodynamic performance of small-size St. Jude Medical aortic prostheses using dobutamine echocardiography. METHODS: Fifteen patients (14 females, one male, of mean age 67 years) who had undergone aortic valve replacement with size 19 mm St. Jude Medical prostheses at a mean of 19 +/- 8 (SD) months previously were studied. Dobutamine infusion was started at a rate of 5 micrograms/kg/min and increased to 10 and subsequently to 20 micrograms/kg/min at 15-min intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area (EOA) and mean gradient across each prosthesis were calculated, and cardiac output (CO) was determined by Doppler measurement of flow in the left ventricular outflow tract. RESULTS: Dobutamine-stress increased heart rate and cardiac output by 57% and 86% respectively (both p < 0.0005), and mean transvalvular gradient increased from 22.0 +/- 4.9 mmHg at rest to 41.9 +/- 9 mmHg at maximum stress (p < 0.0001). Regression modeling analyses demonstrated that maximum stress gradient was independent of all variables except resting gradient (p = 0.0068). Body surface areas had no effect on the changes in cardiac output, effective orifice area or transprosthetic gradient at maximum stress. CONCLUSIONS: These data demonstrate that the size 19 mm St. Jude Medical prosthesis exhibits favorable hemodynamic performance. Transvalvular gradients remained within a clinically acceptable range, both at rest and under stress conditions. Moreover, in the patient population studied, overall hemodynamic performance indicates that with St. Jude Medical aortic valves, patient-prosthesis mismatch is unlikely to be a problem of clinical importance.

Importance of leaflet elongation in causing systolic anterior motion of the mitral valve.

BACKGROUND AND AIMS OF THE STUDY: There is growing evidence for mitral leaflet elongation in patients with hypertrophic cardiomyopathy. Such elongation could predispose to systolic anterior motion (SAM) of the mitral valve by increasing leaflet mobility and providing a geometry that promotes this condition. METHODS: To test this postulate, five porcine mitral valves were studied in a physiologic left heart pulsatile flow duplicator. They were elongated with patches sutured to the basal posterior leaflet (three sizes per valve) or anterior leaflet (basal, middle, or distal). Each geometry was studied with normal papillary muscle position and with anterior and inward displacement, as seen in hypertrophic cardiomyopathy, to shift the leaflets into the outflow stream. RESULTS: Four points became clear. 1) Leaflet elongation promoted the development of SAM in response to papillary muscle displacement by creating long overlapping residual leaflets capable of moving anteriorly. 2) Posterior leaflet elongation also promoted SAM by shifting leaflet coaptation anteriorly, with progressive increases in SAM. 3) Basal and mid-anterior leaflet elongation caused SAM with prolapse; distal anterior leaflet elongation created SAM with a mobile flap (leaflet elongation without papillary muscle displacement created prolapse). 4) Residual leaflet length correlated well with total leaflet length (r = 0.87-0.98 for each valve), and the degree of SAM in turn correlated well with residual leaflet length (r = 0.62-0.98 for individual valves). CONCLUSIONS: Mitral leaflet elongation, by increasing the residual leaflet length and leaflet mobility, can play an important role in promoting SAM in response to outflow forces, as demonstrated by prospectively altering leaflet length. These findings are consistent with recent observations that reducing leaflet redundancy and posterior leaflet height can reduce obstructive SAM following mitral valve repair in patients with mitral valve prolapse and help relieve obstruction in patients with hypertrophic cardiomyopathy and enlarged leaflets.

Prosthetic mitral valve replacement: late complications after native valve preservation.

Preservation of the mitral valve leaflet and tensor apparatus during valve replacement is believed to maintain left ventricular performance. The routine use of this technique may lead to left ventricular outflow or inflow obstruction as illustrated in the present report. We recommend mobilization or excision of the anterior mitral valve leaflet and preservation of the posterior leaflet if replacement of the valve is contemplated for incompetence.

Technique for reconstruction of the sinotubular junction.

Correct geometric relationships between the annulus and sinotubular junction during stentless valve implantation are critical to minimize the development of insufficiency. Some patients with aortic valve disease have dilatation of the sinotubular junction and are unable to have a stentless valve placed by standard techniques. We recently encountered such a patient and reconstructed the sinotubular junction by aortic crenation. Multiple interrupted plicating sutures were used to reduce the aorta from a diameter of 42 mm to 28 mm. This method allows tailoring of the aorta to appropriate size by varying the number of crenating sutures.