The effect of hydroxyethyl starch 6% 130/0.4 compared with gelatin on microvascular reactivity.

We compared the effects on microvascular reactivity of hydroxyethylstarch (Volulyte(®) ) and gelatin (Geloplasma(®) ) during acute haemodilution. The hypothesis was that Volulyte would provide better microvascular reactivity than Geloplasma. Forty patients undergoing elective cardiac surgery were randomly assigned to receive either Volulyte or Geloplasma as the exclusive priming solution of the cardiopulmonary bypass. To evaluate microvascular reactivity, postocclusive reactive hyperaemia was examined before and after cardiopulmonary bypass. Microvascular reactivity assessments included the rate of the occlusion and reperfusion slopes and reperfusion times. After cardiopulmonary bypass, increases in reperfusion time were significantly smaller in the Volulyte group (3 (-27 to 9 [-35 to 33]%) vs 29 (-17 to 76 [-34 to 137]%) in the Geloplasma group, p = 0.02 between groups). Rate of reperfusion increased in the Volulyte group (26 (-17 to 43 [-59 to 357])%), whereas it decreased in the Geloplasma group (-22 (-47 to 16 [-84 to 113])%), p = 0.02 between groups. The shorter reperfusion times and increased reperfusion rate suggest that Volulyte maintains better microvascular reactivity than Geloplasma.

Active or passive bio-coating: does it matters in extracorporeal circulation?

BACKGROUND: Two types of surface coating for cardiopulmonary bypass (CPB) are used: bioactive (heparin, nitric oxide) and biopassive (albumin, polyethyleneoxide (PEO), phosphorylcholine). When haemocompatible coatings are combined with the separation of pleuro-pericardial aspiration, attenuation of both the coagulation and complement cascades, as well as better platelet preservation, has been demonstrated. This study wants to investigate if the combination of a bioactive with a biopassive coating (unfractionated heparin embedded in a phosphorylcholine matrix) combines the beneficial effects of both approaches. MATERIALS AND METHODS: Thirty patients undergoing elective CABG were prospectively randomized into two groups of 15 patients. The sole exclusion criterion was an ejection fraction of less than 40%. In the control group (PC), the whole CPB circuit was coated with phosphorylcholine (PC). In the study group (XPC), unfractionated heparin was embedded in the PC matrix of the oxygenator and arterial line filter. RESULTS: No differences were found for haemolytic index, thrombin-anti-thrombin complex (TAT), IL-6, IL-10 and blood loss. PF4 plasma concentration increased from 27.6±22.0 IU/mL to 165.7±43.9 IU/mL (p<0.001) at 15 minutes of CPB in the PC and from 16.0±9.7 IU/mL to 150.9 ± 61.3 IU/mL (p<0.001) in the XPC group. Terminal complement complex (TCC) increased over time in both groups until the end of CPB (Figure 2A). Within each group, TCC generation was statistically significantly higher after the release of the aortic cross-clamp (p<0.001) and at the end of CPB (p<0.001). Total TCC generation was statistically significantly higher in the XPC group compared to the PC group (p=0.026). The difference was statistically significant after the release of the aortic cross-clamp (p=0.005) and at the end of CPB (p=0.001). CONCLUSIONS: Based on our results, there is no additional benefit in combining phosphorylcholine with unfractionated heparin in elective patients undergoing coronary artery bypass grafting (CABG). Massive haemodilution leads to enhanced complement activation.

The influence of low afterload on the nature of the stress-velocity relationship.

OBJECTIVES: Correct assessment of contractility by conventional methods during manipulation of afterload is often disappointing. To this purpose, the stress-velocity relationship offers assessment of contractility at different levels of afterload. We decided to study the influence of afterload on the nature of the stress-velocity relation. BACKGROUND: Although linear at baseline conditions in a population older than two years, data in newborns or after administration of low-dose dobutamine suggest a different nature of this relationship at low afterload. METHODS: Ten healthy piglets (five to six weeks; 11 to 13 kg) were studied. End-systolic meridional wall stress (ESWS) and rate-corrected velocity of circumferential fiber shortening (VcFc) were measured in these piglets at baseline, after balloon occlusion of the descending aorta, and at nitroprusside infusion rates of 1, 2 and 5 microg/kg/min. To eliminate inotropic influences mediated by reflex tachycardia, we subsequently studied five piglets and six adult pigs after bilateral cervical vagotomy. RESULTS: The ESWS changed from a baseline mean of 50 g/cm2 to 137 g/cm2 after balloon occlusion and to 19 g/cm2 at 5 microg/kg/min of nitroprusside. The VcFc changed from 1.19 c/s (circumference/second) to values of 0.9 c/s and 1.73 c/s, respectively. The ensuing stress-velocity regression line proved to be curvilinear instead of linear. The steeper slope at low afterload could suggest enhanced contractility compared to expected values had the relationship been linear. CONCLUSIONS: Data from young piglets and adult pigs suggest a curvilinear relationship of the stress-velocity relationship. This could probably explain some of the "hypercontractile states" encountered in conditions with low afterload.

Tissue factor as the main activator of the coagulation system during cardiopulmonary bypass.

OBJECTIVE: This study investigates the influence of foreign material and blood aspirated from nonvascular structures on activation of coagulation, hemolysis, and blood loss. METHODS: The series comprises 3 randomized groups (groups C, S, and S+P) of 10 patients undergoing routine coronary artery bypass grafting with cardiopulmonary bypass. In group C, the control group, all aspirated blood was returned into the circulation. In group S suction blood was discarded, whereas group S+P was identical to group S, with surfaces coated with phosphorylcholine. Plasma concentrations of beta-thromboglobulin, thrombin generation, haptoglobin, and free hemoglobin, as well as blood loss, were measured. RESULTS: A steady increase in free plasma hemoglobin, as well as an increased generation of thrombin, was noticed in group C. Moreover, a close correlation (r = 0.916) between the generation of thrombin and its inhibition (thrombin-antithrombin complexes) was observed. Platelets were clearly activated in group C and, to a lesser extent, in group S. In contrast, platelet activation in group S+P was negligible, resulting in a 30% decrease in blood loss (P =.05). CONCLUSIONS: Aspirated blood contaminated by tissue contact is the most important activator of the coagulation system and the principal cause of hemolysis during cardiopulmonary bypass. Contact with a foreign surface is not a main variable in the procoagulant effect of bypass. Mimicking the outer cell membrane structure resulted in decreased platelet activation and decreased blood loss.

Tricuspid valve replacement: postoperative and long-term results.

A series of 146 consecutive patients who underwent tricuspid valve replacement at the University Brugmann Hospital between 1967 and 1987 was reviewed. Mean age at operation was 51.4 years (+/- 12.1 years). Different types of prostheses were implanted including porcine and bovine pericardial bioprostheses and older and bileaflet mechanical valves. Most patients were severely disabled by their cardiac disease before operation, with 30.1% in New York Heart Association functional class III and 69.9% in class IV. Operative mortality and hospital mortality rates (30 days) were high (16.4%). Incremental risk factors for hospital death included icterus (p < 0.005), preoperative hepatomegaly (p = 0.012), and New York Heart Association functional class IV (p = 0.013). Multivariate analysis only selected preoperative icterus (p < 0.01) as being independently significantly related to hospital mortality. The hospital survivors were followed up for a median of 94 months. A complete follow-up was available for all patients except two for 30 months or more. At 30 months the only two significant parameters were the type of myocardial protection (p = 0.024) and the year of operation (before 1977 or after [precardioplegia era or after], p = 0.011). There were 70 late deaths during the entire follow-up period. The univariate (log-rank statistics) incremental risk factor for late death was the type of tricuspid prosthesis (Smeloff-Cutter and Kay-Shiley versus St. Jude Medical versus bioprosthesis) (p = 0.04). A trend was observed for the type of operative myocardial protection (normothermia and coronary perfusion) (p = 0.06) and preoperative New York Heart Association functional class IV (p = 0.055). Actuarial survival was 74% at 60 months and 23.4% at 180 months. Cumulative follow-up added up to 1015 patient-years. In a more detailed analysis of the effect on survival of the type of tricuspid prosthesis, a significant difference was observed between the bioprostheses and some older mechanical prostheses (Smeloff-Cutter and Kay-Shiley) (p = 0.04) but not between the bioprostheses and the bileaflet valves (p = 0.15). When the follow-up period was stratified according to less than 7 years and more than 7 years of follow-up, no difference was observed for the first period, but for the late follow-up the new mechanical prostheses did better than the bioprostheses (p = 0.05), suggesting a degradation of the bioprostheses after 7 years and favoring mechanical prostheses for those patients with a good long-term prognosis.

Feasibility of a pumpless extracorporeal respiratory assist device.

BACKGROUND: Our study evaluated the efficacy and feasibility of a pumpless respiratory assist device and determined its capacity for carbon dioxide removal. METHODS: In five adult pigs the left femoral vein and artery were cannulated with a 20F cannula and connected to a low-pressure hollow-fiber artificial lung. After we had obtained baseline values of mean arterial pressure, cardiac output, and blood flow across the artificial lung, the mean arterial pressure was reduced 20% and 40% relative to baseline; in a second phase, it was raised 20% and 40. Cardiac output and artificial lung flow were simultaneously recorded. We determined the carbon dioxide removal capacity of the artificial lung by gradually increasing the arterial partial carbon dioxide tension of the animal. RESULTS: An increase of 10 mm Hg in mean arterial pressure resulted in an increase of flow of 0.14 L/min. The mean pressure drop across the artificial lung was measured at 17 +/- 9 mm Hg. The shunt flow over the artificial lung varied between 14 and 25% of the cardiac output of the animal. Depending on inlet conditions, carbon dioxide removal by the artificial lung was between 62 +/- 22 mL/L/min and 104 +/- 25 mL/L/min. CONCLUSIONS: A pumpless respiratory assist device can remove a significant proportion of the metabolic carbon dioxide production. However, adequate mean arterial pressure is mandatory to maintain sufficient flow across the device. The technique seems attractive because of its simplicity and can be used in acute lung injury in conjunction of apneic oxygenation for prolonged respiratory support.

Surgical treatment of impending paradoxical embolism through patent foramen ovale.

We describe the case of a patient with deep venous thrombosis who had cerebral and extremity paradoxical emboli and an intracardiac thrombus crossing a patent foramen ovale identified by echocardiography. He was treated successfully with immediate intracardiac embolectomy and closure of the patent foramen ovale.

Deformation of the stentless porcine valve scaffold enhances accelerated leaflet fibrosis and calcification in juvenile sheep.

Stent mounting of xenografts induces a loss of mobility and reduces the effective valve orifice. By contrast, the higher surgical technical expertise required for stentless procedures is a major obstacle for many surgeons. To facilitate the insertion of the Toronto SPV (St Jude Medical Inc, St Paul, Minneapolis, MN) stentless aortic valve, we tried to alter the porcine design by lowering the invasive profile at the depth of the sinuses on both coronary sites. This technique could theoretically facilitate implantation of the modified stentless valve with an easygoing single-layer suture at the challenging subcoronary level and make it more attractive for the surgeon. The standard model was modified by lowering the profile at the depth of the sinuses on both coronary sites, whether by plication (in 3 specimens, one of each size) or excision (in 3 others) of the protruding porcine aortic wall at the nadir of each coronary sinus. Animal implants in juvenile sheep (6 standard Toronto versus 6 modified valves of 21, 23, and 25 mm) were studied for durability and biocompatibility for 3 to 6 months. All valves were evaluated by postoperative echocardiography and after explantation examined macroscopically, radiographically, histologically, and electron microscopically. The standard valves performed well, although at 6 months after implantation, marked fibrosis was found at the outflow parts with scattered calcifications, essentially in the porcine aortic wall. The leaflets remained mobile and contained scant mineralization. By contrast, the modified specimen showed markedly accelerated fibrosis and significant cusp calcifications at distance from the altered zones. Severe restriction of the mobility of the leaflets was visible 3 months after implantation in the juvenile sheep model. The more pronounced the deformation of the modified scaffold, the faster and more intense the degradation and calcification of the leaflets far from the altered zones (worse in the heavily deformed, plicated cusps). Because all valve types were prepared by identical preservation techniques, this study shows that loss of mobility by distortion of the natural scaffold induces early failure. It is extremely important to correct implantation of stentless valves to prevent early degeneration.

Stentless or stented aortic valve implants in elderly patients?

OBJECTIVE: To assess differences in indication and mid-term results between stentless and stented procedures in elderly patients, we followed aortic valve patients over a period of 5 years. METHODS: In a consecutive series of 154 elderly aortic patients in regular sinus rhythm from 1992 to 1997, we inserted 103 stentless (Toronto SPVTM, St Jude Medical Inc., St Paul, Minneapolis, MN) and 51 stented (Carpentier-Edwards supra annular porcine, Baxter Inc., Irvine, CA) bioprostheses in the aortic position. RESULTS: All 154 patients seemed preoperatively eligible for a stentless procedure. Mean age was 74.8 years (range 67-86 years) with a majority of female patients. The surgeon's (in)experience, major dilatation or calcifications of the ascending aorta and aberrant coronary anatomy were the most common reasons for drawback from the stentless procedure (51/154 patients). Aortic clamp time was significantly higher in the stentless vs. stented group (70 vs. 57 min, P < 0.0001). The large average 25.3 mm size of the stentless prostheses (vs. 23.7 mm stented) stands in full contrast with the low mean body surface area of 1.68 m2 (vs. 1.70 m2) of the patients. We encountered. respectively. 5 and 2 hospital-deaths (P = n.s.). The follow-up period ranged from 6 to 66 months and was 97% complete, yielding, respectively, 302 and 139 patient-years. Survival (Kaplan-Meier method) was statistically higher in favor of the stentless procedures (log rank: P = 0.03). All survivors progressed markedly to a mean postoperative NYHA class 1.3 respectively, 1.4 (vs. preop. 3.3 and 3.2). Echocardiographic transvalvular gradients compared favorable for the stentless group in the small under 25 mm valves (P = 0.02 for 23 mm sized valves between groups) with improved left ventricular function and a significant decrease of left ventricular end diastolic diameter (LVEDD 48.0 vs. 56.5 mm) at 1 year follow-up. Cusp calcifications on control echocardiography were detected earlier (beyond 3 years) in the stented group, without signs of early significant regurgitation or dysfunction in both groups, except for one patient necessitating re-operation. CONCLUSION: Although the implantation technique is much more demanding for stentless procedures, reflected by a longer aortic clamp-time, and remains impossible in some cases, elderly, small sized patients take full benefit of their large, non-obstructive prostheses.

In vivo evaluation of a phosphorylcholine coated cardiopulmonary bypass circuit.

A complete phosphorylcholine coated cardiopulmonary bypass circuit, including the Dideco D901 oxygenator, was tested for gas transfer, blood path resistance, and biocompatibility in a standardized setting. Blood compatibility was tested by measuring complement and platelet activation. Three dogs (mean body weight 28 +/- 3 kg) were placed on cardiopulmonary bypass at a flow rate of 600 mL/min during 6 hours. The animals were weaned from cardiopulmonary bypass and sacrificed electively after 7 days. Oxygen and carbon dioxide transfer were 26.6 +/- 2.4 mL/min and 33.0 +/- 1.9 mL/min, respectively. Mean pressure drop across the oxygenator was 52.6 +/- 0.2 mmHg. The respective baseline values for thromboxane B2, prostaglandin E2 and platelet factor 4 were 1817 +/- 283 pg/mL, 12783 +/- 2109 pg/mL, and 0.35 +/- 0.08 IU/mL. Thromboxane B2 and prostaglandin E2 increased slightly to 2881 +/- 868 pg/mL and 18083 +/- 3144 pg/mL at 30 minutes of bypass, whereas platelet factor 4 values remained stable curing the procedure. Concentrations of complement split products C5a were only mildly increased. After use scanning electron microscopy was performed on the inner housing, heat exchanger, and outer surface of the hollow fibers. No thrombi nor organized cellular deposits were found on any of the components. Phosphorylcholine coating of CPB seems to be very promising regarding platelet activation and complement activation.

[Long-term follow-up after Kaunitz repair of hiatal hernia]. / Lange termijn follow-up na herstel van hiatus hernia volgens Kaunitz.

Kaunitz-procedure for gastro-oesophageal reflux. Between May '74 and May '86 we performed 121 Kaunitz-procedures for gastro-oesophageal reflux, mostly with oesofagitis. Follow-up was obtained in 120 of these 121 patients. The mean follow-up is 55 months and the mean age 49.5 years at the time of operation. Of these patients 103 were completely free of reflux-symptoms after the operation while 6 patients had apparent amelioration of their symptoms. In 7 patients we obtained no subjective improvement but in 4 of them the oesofagitis, which they had preoperatively, has disappeared. 4 patients were reoperated because of anatomical recurrence. The results can be considered as good or excellent in 94% of the patients. The Kaunitz procedure is a simple and efficient operative technique in patients with hiatus hernia and reflux.

Operative outcome of minimal access aortic valve replacement versus standard procedure.

BACKGROUND: to determine the advantages and/or risks of minimal access aortic valve replacement compared to standard sternotomy procedure. METHODS: from January 1997 to December 2001, 271 consecutive adult patients underwent isolated aortic valve replacement of which 174 underwent a minimal access procedure (Group 1) and 97 a standard procedure (Group 2). The preoperative variables of both groups were comparable. Retrospective analysis of postoperative outcome was performed. RESULTS: follow-up was complete and ranged from 6 months to 4 years. Overall in-hospital mortality was 3.3% (respectively 2.8 and 4.1%). No statistical difference was noted regarding operative time variables, mortality rate and hospital stay. There was a significant higher incidence of revision (p = 0.018) and late pericardial effusion (p = 0.022) in the minimal access group. Also trends were in favour of the standard group for incidence of postoperative pneumothorax and pericarditis constrictiva. CONCLUSIONS: minimal access aortic valve replacement is a safe and reliable technique, but carries the risk of incision-related morbidity. Proper patient selection and perioperative management is mandatory.

Intramyocardial paravalvular abscess after aortic valve replacement.

Myocardial abscess is a rare but life-threatening disease with various clinical presentations. We describe the case of a paravalvular abscess distending intramurally 7 years post surgery for aortic valve replacement. Early detection and urgent surgical intervention is essential for this otherwise fatal disease entity.

Haemostasis monitoring during sequential aortic valve replacement and liver transplantation.

Despite advances in anaesthesiological and surgical techniques, cardiac surgery in cirrhotic patients remains hazardous. This report outlines our experience with haemostasis monitoring in two consecutive cases of sequential aortic valve replacement and liver transplantation. Clotting disturbances proved to have fatal consequences since one of these patients died following massive lung embolism. The second patient underwent successfully this combined procedure and is in good clinical state 14 months postoperatively. Evaluation and discussion of the coagulation monitoring by the Sonoclot Analyzer in both patients and related therapeutic suggestions for the prevention of thrombotic events are discussed.

A subcutaneous lead array for implantable cardioverter defibrillators.

Two patients received an implantable cardioverter defibrillator with the combination of a transvenous lead and a subcutaneous lead array with three branches. This approach allowed us to find low defibrillation thresholds in both patients (< or = 10 and < or = 15 joules [J], respectively), which was impossible with a transvenous catheter. In a third patient, a crinkled subcutaneous patch was replaced by an array. The defibrillation threshold with the array was < or = 20 J, as opposed to > 24 J with the patch. No surgical problems occurred. The subcutaneous array is a technical improvement for the therapy with implantable defibrillators, when a single catheter system is not sufficient to ensure a safety margin for defibrillation, or when surgical or postsurgical problems occur with a subcutaneous patch.

Removal of endocardial defibrillation leads.

Two patients, each with an endocardial defibrillation lead system (Endotak O62), required lead removal; one because of chronic lead infection and the second because of spurious shocks caused by lead insulation damage. Neither lead could be removed by simple traction. The defective lead was removed by a combination of catheterization techniques including a steerable ablation catheter and traction, both under general anesthesia. The lead with the insulation defect was rapidly removed with a locking stylet, suggesting that endocardial lead defibrillating leads can be removed similarly to pacemaker leads, thus avoid thoracotomy.

Transcatheter treatment of angina after coronary surgery due to concomitant internal mammary steal and right coronary artery stenosis: a need for staging.

Unligated side branches of the internal mammary artery used as a conduit in bypass surgery can be responsible for a flow steal phenomenon, causing recurrent angina. In this report we describe such a case, which was treated with a transcatheter embolization technique using coils as an alternative to surgery. However, heparin administration for simultaneous balloon dilatation of another lesion delayed successful embolization. Whenever balloon dilatation and embolization have to be performed on the same patient, both procedures should be staged to avoid heparin administration during and after the embolization procedure.

Haemodynamic effects of R 80122 immediately after cardiopulmonary bypass; preliminary results.

R 80122 is a new short-acting phosphodiesterase type III inhibitor. In a preliminary investigation, three patients, scheduled for coronary artery bypass surgery, were given R 80122 after weaning from cardiopulmonary bypass. Two patients received 10 micrograms.kg-1.min-1 for 10 min as a loading infusion followed by a 5 micrograms.kg-1.min-1 maintenance dose. One patient received a 20 micrograms.kg-1.min-1 for 10 min loading infusion followed by a 10 micrograms.kg-1.min-1 maintenance infusion. After weaning from cardiopulmonary bypass and during the administration period, no arrhythmias or cardiac ischaemia were detected. The administration of R 80122 improved the haemodynamic profile with an increase in cardiac output, a decrease in systemic vascular resistance and a stable heart rate and mean arterial blood pressure. These preliminary results indicate that R 80122 possesses positive inotropic activity in combination with vasodilating properties.

Clinical experience with the first 100 ATS heart valve implants.

Between May 1992 and March 1994, 100 consecutive patients had 119 new ATS mechanical bileaflet valves inserted (61 aortic, 50 mitral, eight tricuspid). The mean age of the patients was 63.7 (range 13-82) years. The follow-up period ranged from 5 to 27 months and was complete in all cases. Before surgery, 53 aortic valve patients were in New York Heart Association functional class III or higher. This improved to a mean of 1.3 postoperatively, all patients being in classes I or II. One patient died in hospital, and another 3 months after implantation (actuarial survival rate 98%). One patient had an embolic event 9 days after an aortic valve reoperation which caused a parietal infarction. One tricuspid valve blocked in the open position 6 weeks after implantation as a result of inadequate anticoagulation and was successfully unblocked after 2 days of intensive thrombolytic therapy. Patients were treated by mild anticoagulation without developing bleeding complications. Echocardiographic, transoesophageal and transthoracic valvular gradients compared favourably with the gradients reported in other mechanical valves (including small aortic valves). The haemodynamics were excellent without evidence of significant regurgitation. This was confirmed by an in vitro hydrodynamic evaluation of the valve using a pulse duplicator system. The valve closure caused little noise and was as a result well tolerated.

Pulse duplicator hydrodynamics of four different bileaflet valves in the mitral position.

The hydrodynamic performance of four different types of bileaflet heart valve was tested both in steady flow conditions and in a newly designed computerized artificial left heart system. Four 29-mm valves, manufactured by either St. Jude Medical, CarboMedics, ATS Medical or Medtronic Parallel were studied under a steady state and in pulsatile conditions by pressure and flow recording and colour Doppler echocardiography in the 'mitral position' at rest and at exercise (cardiac output range 4-30 l/Min). In the steady state, significant differences were measured at peak flows of 30 l/min, with mean (s.d.) increasing pressure drops (mmHg) recorded at 3.48(0.13) (St. Jude Medical), 3.80(0.11) (Medtronic Parallel), 4.31(0.06) (ATS Medical) (P < 0.005), and 4.78(0.06) (Carbo Medics), (P < 0.005). The mean ratio of the closing volume to the stroke volume was comparable for all valves despite one faulty sample. In the pulsatile state the effective orifice area calculated by the Continuity and Gorlin equations decreased from 2.10(0.04) (ATS Medical), 1.95(0.05) (St. Jude Medical), 1.87(0.03) (Carbo Medics) to 1.67(0.02) (Medtronic Parallel) independently of method used. No significant difference was found in the mean ratio of the regurgitant volume to the stroke volume. The performance index, defined as the ratio of effective orifice area to geometric orifice area ranks the valves in the order ATS Medical (0.44), St. Jude Medical (0.43), Carbo Medics (0.41) and Medtronic Parallel (0.38). Regurgitation visible on colour Doppler echo was a mere consequence of the working principle of the bileaflet valves in the mitral position and was by no means hydrodynamically important nor representative of severe insufficiencies. Differences between the valve types were notable under severe conditions, such as high peak flow.