Prospective, Randomized Un-Blinded Three Arm Controlled Study in Coronary Artery Revascularization with Minimal Invasive Extracorporeal Circulation Systems (MiECC): Surrogate Parameter Analysis of Biocompatibility.

OBJECTIVES: Minimal extracorporeal circulation techniques and systems (MiECC) may reduce the negative side effects of conventional extracorporeal circulation (ECC). However, it is still unclear as to what this is caused by, the reduced priming volume and hemodilution, or the avoidance of blood-air contact and dispersion of mediastinal debris into the systemic circulation. The aim of the trial was the comparison of MiECC to an open ECC setup (openECC) or a system with reduced blood air and debris interaction (closeECC). Methods: In a prospective randomized trial, 72 patients (73 ± 5.3 years; 83% male) referred for coronary artery bypass graft (CABG) were randomly assigned either to MiECC (priming volume 550mL), closeECC, or openECC (priming volume 1250mL). The laboratory surrogate endpoints (renal function, inflammatory response, ischemia, coagulation, and hemolysis) and clinical data were measured at six different time points (T1-6). Results: Patients were comparable for all preoperative variables. The operation times (MiECC 261 ± 79min; openECC 264 ± 75min; closeECC 231 ± 68min) and perfusion times (MiECC 115 ± 49min; openECC353 107 ± 37min; closeECC 99 ± 22min) revealed a trend of faster performance in the closeECC group (P < .05). Pro-inflammatory cytokines, ischemia, and coagulation markers were significantly elevated postoperatively in all cardiopulmonary bypass types, and decreased to pre-baseline levels at discharge (T5) without identifiable statistical differences between the three study groups. Free-hemoglobin was not significantly increased by centrifugal pump or cell saver procedures. Significant intraoperative hemodilution effects due to the different priming volumes were demonstrated only at the end of operation (T2) (MiECC Hb 9.6 ± 1.1g/dL; openECC Hb 9.0 ± 0.8g/dL; closeECC Hb 8.7 ± 1g/dL; P =. 01). CONCLUSION: Neither the hemodilution, suction technique (MiECC), nor blood-air interface (closeECC) could show sustainable benefits in this underpowered study, compared to conventional ECC systems (openECC) in a high volume series of surrogate parameters.

Hemodynamic Consequence of Different Pacing Modes after Aortic Valve Replacement.

OBJECTIVES: Ventricular pacemaker stimulation may cause deterioration of hemodynamics in patients with left-ventricular hypertrophy following aortic valve replacement. Since the diastolic function is often impaired, it remains unclear which heart rate best optimizes cardiac output. Low heart rates are suggested to treat impaired diastolic function chronically, but it is possible that cardiac output may be augmented by increasing the heart rate in patients with a fixed stroke volume (SV). The aim of this study is the identification of the best pacing mode and heart rate for the surrogate parameter SV and cardiac index(CI) in patients with left ventricular hypertrophy. METHODS: Various pacemaker stimulation modes and different heart rates, as well as their influence on hemodynamics, were tested following aortic valve replacement in 48 patients with severe left-ventricular hypertrophy (Intraventricular septum (IVS)>1.5 cm) and aortic stenosis. SV and cardiac output were recorded by pulse curve analysis. Four modes of stimulation (right ventricular pacemaker stimulation (DDDright), left ventricular pacemaker stimulation (DDDleft), biventricular pacemaker stimulation (DDDbi), atrial pacemaker stimulation (AAI)) were documented at five different rates (60, 80, 100, 120, 140 beats/min) and three different postoperative time points (intraoperatively, 3h and 24h postoperatively). RESULTS: The highest CI was found at linear rates between 60 to 140bpm. AAI was the best mode of stimulation in the majority of cases (35%), but in others, either left, right and/or biventricular stimulation was found to be better (15%). SV showed a u-shaped trend with a peak at 100 beats/min. CONCLUSION: An increase in the heart rate does not lead to a notable drop in SV postoperatively in left-ventricular hypertrophy; hence a rise in cardiac output can be anticipated up to a rate of 100 beats/min. A standardized response in terms of an ideal pacemaker stimulation mode could not be identified.

Real-time measurement of rectal mucosal microcirculation during cardiopulmonary bypass.

OBJECTIVES: Mesenteric ischemia is still a fatal event after cardiac procedures. No adequate intraoperative methods are available to monitor the gastrointestinal mucosal microcirculation in real-time conditions. The aim of the study was to assess a newly designed microprobe using laser Doppler flowmetry and remission spectroscopy. DESIGN: One-group, prospective, nonrandomized, open, pilot diagnostic study. SETTING: Monocenter university hospital. PARTICIPANTS: 50 patients (n = 38 males, 67±6 years) scheduled for cardiopulmonary bypass (CPB) were prospectively included. INTERVENTION: During anesthetic induction, the transrectal microprobe (30×15 mm) was positioned between the inferior and middle rectal valve (5-8 cm). Time periods were summarized at T1 = pre-CPB, T2 = CPB, T3 = post-CPB. MEASUREMENTS AND MAIN RESULTS: In 39 of 50 patients, data recruitment with the microprobe was successful. Measurement failures were due to fecal contaminations and probe dislocations. Rectal blood flow and velocity significantly decreased after bypass initiation (T2). Lowest flow rates were recorded after cross-clamp removal and did not recover at the end of bypass (T3). No side effects of the probe were noted. CONCLUSIONS: The new microprobe allows reproducible, safe, intraoperative, real-time evaluation of the rectal mucosal microcirculation. It could be a useful diagnostic tool to prevent mesenteric ischemia by optimizing extracorporeal circulation in future studies. However, first correlation of rectal blood flow and postoperative events (eg, ischemia, lactate) in a large cohort are necessary.

Midterm follow up in patients with reduction ascending aortoplasty.

BACKGROUND: The reduction ascending aortoplasty in patients with an aortic ectasia/dilatation is a common procedure during concomitant cardiac operations. Aim of the follow up study was the evaluation of possible re-dilatation and complications. METHODS: From 1998 to 2010 124 patients (69% male; mean age 66.6 ± 12 ys) with ectasia of the ascending aortic who had no further indication for an aortic replacement, were included. The mean preoperative diameter of the ascending aorta was 4.2 ± 0.6 cm. The patients risk profile was moderate (mean EF 51% ± 11%, Euroscore 4.2 ± 2.1). To treat the dilatation of the ascending aorta, a longitudinal incision was performed and a strip of the aortic wall was resected. A reduction aortoplasty was carried out with a double-layered suture line using a 4/0 Prolene mattress suture with an additional 4/0 Prolene running suture. A follow up (rate 95%) was performed by echocardiography- and clinical examination. RESULTS: All patients underwent reduction aortoplasty associated with a primary cardiac surgical procedure (AVR 63%, CABG 13%, other or combination 24%). The intrahospital mortality rate was 4%. Four aortic bleeding complications occurred. After a mean postoperative period of 57 ± 39 months, the ascending aortic diameter (3.6 ± 0.6 cm) was still significantly (P < 0.01) reduced. No postoperative aortic-related complications including aortic rupture, dissection and reoperation were observed. In 4 patients, the ascending aorta had re-dilated to the preoperative diameter. CONCLUSION: Reduction ascending aortoplasty without external wrapping is a safe procedure with acceptable midterm results in patients with asymptomatic dilatations and concomitant cardiac surgical procedures.

Long-term follow-up of minimally invasive cardiac surgery using an endoaortic occlusion system.

OBJECTIVES: We reviewed the initial patient series (n=116) of our institution performing minimally invasive coronary artery bypass grafting (CABG) (n=79), mitral valve surgery (n=1), or atrial septal closure (ASD) procedures (n=26) using an endoaortic occlusion system. With this technique relevant intra-aortic pressures are exerted on the aortic wall during the clamping time. This might lead to late aortic degeneration and aneurysm formation. Our study sought to evaluate postoperative aortic complications and the quality of life (modified SF-12). METHODS: One hundred sixteen patients (56% male; 54 years ± 14.5; range 19 years to 77 years) underwent a cardiac procedure using an endoaortic clamp. The endoaortic balloon clamp catheter was used to occlude the ascending aorta at pressures >300 mmHg. Patients were rescheduled for echocardiographic examination after a mean follow-up period of 8.8 years. RESULTS: The analysis performed among 78 patients showed no incidence of any structural damage to the ascending aorta at the intraoperative position of the endoaortic balloon. The physical and mental summary scores are equal to those of comparable patient groups. CONCLUSIONS: The endoaortic occlusion system causes no damage to the aortic wall. If the system causes any problems, they occur immediately during surgery. Patients treated with this minimally invasive technique exhibited the same quality of life as those undergoing conventional surgery.

Risk factor analysis for fast track protocol failure.

BACKGROUND: The introduction of fast-track treatment procedures following cardiac surgery has significantly shortened hospitalisation times in intensive care units (ICU). Readmission to intensive care units is generally considered a negative quality criterion. The aim of this retrospective study is to statistically analyse risk factors and predictors for re-admission to the ICU after a fast-track patient management program. METHODS: 229 operated patients (67 ± 11 years, 75% male, BMI 27 ± 3, 6/2010-5/2011) with use of extracorporeal circulation (70 ± 31 min aortic crossclamping, CABG 62%) were selected for a preoperative fast-track procedure (transfer on the day of surgery to an intermediate care (IMC) unit, stable circulatory conditions, extubated). A uni- and multivariate analysis were performed to identify independent predictors for re-admission to the ICU. RESULTS: Over the 11-month study period, 36% of all preoperatively declared fast-track patients could not be transferred to an IMC unit on the day of surgery (n = 77) or had to be readmitted to the ICU after the first postoperative day (n = 4). Readmission or ICU stay signifies a dramatic worsening of the patient outcome (mortality 0/10%, mean hospital stay 10.3 ± 2.5/16.5 ± 16.3, mean transfusion rate 1.4 ± 1,7/5.3 ± 9.1). Predicators for failure of the fast-track procedure are a preoperative ASA class > 3, NYHA class > III and an operation time >267 min ± 74. The significant risk factors for a major postoperative event (= low cardiac output and/or mortality and/or renal failure and/or re-thoracotomy and/or septic shock and/or wound healing disturbances and/or stroke) are a poor EF (OR 2.7 CI 95% 0.98-7.6) and the described ICU readmission (OR 0.14 CI95% 0.05-0.36). CONCLUSION: Re-admission to the ICU or failure to transfer patients to the IMC is associated with a high loss of patient outcome. The ASA > 3, NYHA class > 3 and operation time >267 minutes are independent predictors of fast track protocol failure.

Mid-term follow up of a novel bioprosthesis in aortic valve surgery.

BACKGROUND AND AIM OF THE STUDY: The BioPhysio bioprosthesis (Edwards Lifesciences LLC, Irvine, CA, USA) was designed to further improve the hemodynamic performance currently achieved by stented valves. A flexible Nitinol stent that preserves aortic root dynamics, thus maximizing the effective orifice area (EOA), is a key innovation of this prosthesis. The study aim was to provide a clinical evaluation of this new device. METHODS: Between December 2004 and August 2005, a total of 50 patients (27 males, 23 females; mean age 75.8 +/- 5.1 years; range: 55-84 years) received a BioPhysio aortic bioprosthesis. Clinical outcomes, EOAs, mean gradients and regression of left ventricular hypertrophy were evaluated echocardiographically at discharge, and at six, 12, 24, 36, 48, and 60 months after surgery. RESULTS: The 60-month follow up was complete for all patients. No patients died within 30 days of surgery, but the late mortality was 14% (n = 6). There was one sudden unexplained death. One patient developed endocarditis at two years after surgery and underwent reoperation. There were no cases of stroke or renal failure. The BioPhysio prosthesis showed a good hemodynamic performance, with a significant fall in mean gradient to 15.1 +/- 8.3 mmHg, a mean EOA of 1.5 +/- 0.7 cm2, and a mean ejection fraction of 61 +/- 7.2%. There were no cases of aortic regurgitation. The NYHA functional class was improved in all patients, and there was a significant reduction in the left ventricular mass index to 185.7 +/- 49.6 g/m2 at 24 months. CONCLUSION: The clinical performance of the BioPhysio aortic bioprosthesis is comparable to that of regular stentless aortic valves. However, clinical approval for the widespread use of this bioprosthesis was not obtained.

Comparative evaluation of left ventricular mass regression after aortic valve replacement: a prospective randomized analysis.

BACKGROUND: We assessed the hemodynamic performance of various prostheses and the clinical outcomes after aortic valve replacement, in different age groups. METHODS: One-hundred-and-twenty patients with isolated aortic valve stenosis were included in this prospective randomized randomised trial and allocated in three age-groups to receive either pulmonary autograft (PA, n = 20) or mechanical prosthesis (MP, Edwards Mira n = 20) in group 1 (age < 55 years), either stentless bioprosthesis (CE Prima Plus n = 20) or MP (Edwards Mira n = 20) in group 2 (age 55-75 years) and either stentless (CE Prima Plus n = 20) or stented bioprosthesis (CE Perimount n = 20) in group 3 (age > 75). Clinical outcomes and hemodynamic performance were evaluated at discharge, six months and one year. RESULTS: In group 1, patients with PA had significantly lower mean gradients than the MP (2.6 vs. 10.9 mmHg, p = 0.0005) with comparable left ventricular mass regression (LVMR). Morbidity included 1 stroke in the PA population and 1 gastrointestinal bleeding in the MP subgroup. In group 2, mean gradients did not differ significantly between both populations (7.0 vs. 8.9 mmHg, p = 0.81). The rate of LVMR and EF were comparable at 12 months; each group with one mortality. Morbidity included 1 stroke and 1 gastrointestinal bleeding in the stentless and 3 bleeding complications in the MP group. In group 3, mean gradients did not differ significantly (7.8 vs 6.5 mmHg, p = 0.06). Postoperative EF and LVMR were comparable. There were 3 deaths in the stented group and no mortality in the stentless group. Morbidity included 1 endocarditis and 1 stroke in the stentless compared to 1 endocarditis, 1 stroke and one pulmonary embolism in the stented group. CONCLUSIONS: Clinical outcomes justify valve replacement with either valve substitute in the respective age groups. The PA hemodynamically outperformed the MPs. Stentless valves however, did not demonstrate significantly superior hemodynamics or outcomes in comparison to stented bioprosthesis or MPs.

Tremendous bleeding complication after vacuum-assisted sternal closure.

Vacuum-assisted closure (VAC) of complex infected wounds has recently gained popularity among various surgical specialties. The system is based on the application of negative pressure by controlled suction to the wound surface. The effectiveness of the VAC System on microcirculation and the promotion of granulation tissue proliferation are proved. No contraindications for the use in deep sternal wounds in cardiac surgery are described. In our case report we illustrate a scenario were a patient developed severe bleeding from the ascending aorta by penetration of wire fragments in the vessel. We conclude that all free particles in the sternum have to be removed completely before negative pressure is used.

Evaluating a new method for maintaining body temperature during OPCAB and robotic procedures.

BACKGROUND: We evaluated the performance of a new temperature management system (Allon Thermowrap, MTRE, Israel) in maintaining normothermia during OPCAB (Off-Pump Coronary Artery Bypass) procedures and Zeus-robotic IMA (internal mammary artery) takedowns. MATERIAL/METHODS: One hundred patients were prospectively randomized to either a conventional temperature management method (thick blanket, warm intravenous fluids, operating room temperature 25 degrees C), or the new Allon Thermowrap system (pads with temperature-controlled water circulation placed on the patient's back, legs, and arms). The mean age, body surface area, total operating time, and OR air temperature were similar in both groups. RESULTS: The Allon Thermowrap system maintained a higher bladder and nasopharyngeal temperature (p<0.05). The SVR decreased (p<0.05) and the cardiac index increased (p<0.05) in patients with a body temperature>35.80 degrees C. Without reaching a significant level, the postoperative blood loss was lower in the Allon Thermowrap group. CONCLUSIONS: The Allon Thermowrap system significantly out-performed conventional techniques in achieving and maintaining normothermia during off-pump and robotic procedures.

Advanced sternal closure to prevent dehiscence in obese patients.

Sternal dehiscence is a frequent complication after cardiac surgical procedures. The objective was to evaluate a novel method for advanced sternal closure compared with standard techniques for preventing sternal dehiscence. Our investigation comprised 100 patients with a body mass index above 32. Patients were randomly assigned to receive either advanced sternal closure with three stainless steel double wires or standard techniques with stainless steel single wires. The incidence of sternal refixation was 6 of 50 patients in the standard techniques group and 1 of 50 in the advanced sternal closure group during a follow-up period of 6 months.

Blood-air interface during cardiopulmonary bypass.

The aim of this study was to compare the systemic blood activation with open and closed perfusion management during cardiopulmonary bypass. In 30 patients undergoing coronary artery bypass grafting, we prospectively studied systemic blood activation, blood loss and the need for donor blood. In 15 patients we used an open venous reservoir consisting of a hard shell venous reservoir with an integrated cardiotomy filter. In another 15 patients we used a totally closed venous reservoir consisting of a collapsible venous reservoir, no coronary suction, modified vent and cell saver. Venous blood samples were collected pre, post and 24 hours postoperatively. Sex, age and perfusion times were identical in both groups. There were no statistically significant differences in concentrations of FXIIa and C3a, amount of blood loss and need for donor blood. Interleukin-6 and Elastase levels showed trends toward a lesser inflammatory reaction in closed venous reservoir patients. Modification of perfusion management with optimized air management does not seem to be an effective strategy in reducing the inflammatory response and influencing the coagulation system in this small cohort.

Intracardiac left ventricular support in beating heart, multi-vessel revascularization.

BACKGROUND: Less invasive operation procedures without support of extracorporeal circulation are becoming increasingly important. A basic requirement for good long-term results in such cases is, however, the complete revascularization of the affected coronary vessels. The unsatisfactorily high conversion rate from bypass operations originally planned as off-pump to conventional operations with heart-lung machines, because of the failure to reach the target vessels on the rear wall of the heart through hemodynamic instability led to investigation of the efficiency of a microaxial pump (Impella elect) placed in the left ventricle. METHODS: In a prospective project 15 of 38 consecutive patients selected for coronary revascularization with beating heart had a micro pump transaortically implanted in the left ventricle to support the heart during the operation with a flow rate of 2.5 to 3.9 l/min. RESULTS: With 8 of 23 patients operated on without pump support, the operation had to be converted to conventional methods with a heart-lung machine. Only one patient out of the left-ventricle-supported group had to be further operated on conventionally because of a deep intramyocardial positioned left anterior descending coronary artery (LAD) (p < 0.05). The investigated laboratory parameters, especially creatine kinase (CK), CK-MB isoenzyme, and clotting showed no significant difference. There tended to be a higher blood loss recorded with the pump-supported patients. CONCLUSION: In summary, it appeared that the application of a left ventricular coaxial pump with comparable results seemed to make possible complete revascularization in nearly all patients.

Topical application of aprotinin in cardiac surgery.

The aim of our study was to compare a systemic and a local aprotinin application in patients during coronary artery bypass graft (CABG) surgery. The advantage of a topical aprotinin application is seen in the fact that this may not lead to systemic side effects. A prospective, randomized study comprising 97 patients was conducted. A dose of 5 x 10(6) KIU aprotinin was given systemically to 49 patients and four doses of 1.25 x 10(6) KIU aprotinin were applied topically to 48 patients by spraying the substance on the target area (A. mammaria interna region and pericardium). We determined markers for the inflammatory response, coagulation system, standard haematological markers and postoperative complications. Exclusion criteria were defined as surgical bleeding, redo operations, neurological, haematological, liver and kidney disorders. Sex, age, perfusion times, mortality, renal failure and strokes were identical in both groups. Biochemical markers and clinical outcome demonstrated no significant differences between the systemic and local applications. Interleukin 6 and elastase were tendentially higher (p = 0.1) in the local group, but with a high standard deviation in each patient. Our results suggest that there is no difference between the perioperative application of 5 x 10(6) KIU systemically given aprotinin and 1.25 x 10(6) KIU locally applied aprotinin.

Platelet function test HemoSTATUS 2: tool or toy for an optimized management of hemostasis?

BACKGROUND: Bleeding after open heart surgery is a common but unintended problem, which is unequivocally related to platelet function. The target of our study was to correlate platelet activation levels and postoperative blood loss as well as the predictive power of measurements focusing on postoperative hemostasis. MATERIALS AND METHODS: The prospective trial comprised 100 patients (mean age: 64.3 years, 68% male) undergoing cardiac surgery. Platelet activation was measured by the new and modified HemoSTATUS test. Blood samples were drawn pre-, intra- and postoperatively. Standard hemostasis tests, including activated clotting time (ACT), partial thromboplastin time (PTT), hemoglobin, platelet count, antithrombin III (AT III) and fibrinogen, were measured according to the clinical routine. Blood loss and consumed blood products were documented up to the 24th hour after the operation. RESULTS: Platelet activation showed a typical change, with lowest levels after the end of extracorporeal circulation and a restitution to preoperative levels after 24 h. Mean blood loss was 461 ml. Statistical analysis showed neither a correlation to the platelet activation measurements nor to low pre-, intra- or postoperative levels. CONCLUSION: The HemoSTATUS platelet function test is not suitable for a reliable monitoring of platelet pathophysiology and patient outcome after extracorporeal circulation. Furthermore, no correlation of preoperative platelet activation and blood loss could be shown.