[Video-assisted cardiac valve surgery]

BACKGROUND AND PURPOSE

Advances in the development of video-assisted systems for minimally invasive surgery now allow to perform cardiac surgery via a smaller anterolateral thoracotomy in order to reduce trauma, pain and improve cosmetics. In addition, due to sternal sparing, pulmonary function should improve resulting in reduced hospital stay and costs. However, only few centers worldwide abstain from spreading the ribs thus accepting considerable pain and reduced patient comfort. The minimally invasive approach described here uses a right-sided anterolateral incision (4-5 cm), a soft-tissue retractor and femorofemoral perfusion with endoclamping under continuous TEE (transesophageal echocardiography) control. It was the aim of this retrospective analysis to determine feasibility, safety and effectiveness of the method.

PATIENTS AND METHODS

At the West German Heart Center Essen, 47 patients were operated using minimally invasive endoscopic techniques between January 2004 and April 2006 on the mitral valve (n = 31), mitral and tricuspid valve (n = 9), including mini-Maze procedure in two cases, as well as atrial septal defects (n = 5) and myxomas (n = 2). Mean age was 58 +/- 15.2 years (range 29-87 years), NYHA II-III, 20 patients were male.

RESULTS

All but one patient survived (2.1%). Conversion to median sternotomy was necessary in three of the first twelve patients. After a mean follow-up period of 18 months all reconstructions and valves were competent, freedom from cardiac reoperation was 100%. On a visual analog scale 91% ot the patients reported no or mild postoperative pain, 96% felt they had an aesthetically pleasing scar. All but one patients would choose the same operation again.

CONCLUSION

Videoscopically assisted, endoscopic cardiac surgery can be performed safely, but requires a learning curve and intense training. After evaluation of efficacy and safety it is now the authors' exclusive approach to isolated atrioventricular valve disease with an ideal pain-free and cosmetic result.

Paradigmenwechsel in der Chirurgie der komplexen thorakalen Aortenerkrankung

One of the main issues in complex thoracic aortic disease, requiring the replacement of the ascending aorta, the entire aortic arch and the descending aorta, is the vast amount of surgery necessary to cure the patient. Though one-stage repair is feasible by a clamshell thoracotomy, the associated surgical trauma and perioperative morbidity limit this approach to younger patients only. Classic surgical repair consist of a two-stage strategy, whereby, in the first step, the ascending aorta and the aortic arch are replaced via a midline sternotomy. In the second step, via a lateral thoracotomy, the descending aorta is replaced. The two stages may sum up to a mortality of 20%; furthermore, the waiting period between the stages is associated with a mortality rate of 10% of its own. Additionally, the two-stage strategy has an inherent limitation, due to the comorbidity and advanced age of the majority of patients. Therefore, the second stage cannot be offered to up to 30% of patients. New developments and improvements in aortic surgery were introduced to overcome these shortcomings and to simplify the surgical repair. The "elephant trunk" principle, introduced by Borst et al. in 1983, was an important step to facilitate surgical repair, but still required the second step. With the introduction of endovascular repair of thoracic aortic disease with stent grafts implanted retrograde via the femoral artery, new therapeutic concepts emerged. In the late 1990s, two Japanese groups reported first trials to stabilize the free-floating "elephant trunk" prosthesis by implantation of nitinol stent grafts into the vascular graft. The applied devices were purely custom-made and nonstandardized. The availability of industrially made and CE-marked stent-graft devices raised the possibility to apply them in open aortic arch surgery. The experience with stent-graft devices implanted antegrade into the descending aorta (Medtronic Talent) was reported first by the Essen and the Vienna group. The experience gained with these devices revealed the limitations of the devices designed for pure retrograde aortic delivery. This required a complete redesign and new construction of the stent graft itself as well as the introducer system. In a preliminary series of 14 patients the required stent-graft properties were presented in detail and resulted in the first industrially manufactured standardized and CE-marked Hybrid stent graft (Essen 1 prosthesis, E-vita Open, Jotec), especially made for antegrade open stent grafting of the descending aorta. This device consists of a stent graft with an integrated Dacron vascular prosthesis, enabling for direct and continuous aortic arch replacement after stent grafting of the descending aorta. From 01/2005 to 03/2006, this hybrid prosthesis was implanted in 16 patients (one aneurysm and 15 aortic dissections). In all cases, the underlying pathology within the thoracic aspect of the aorta could be excluded in a one-stage approach. In case of aortic dissection, thrombosis of the false lumen was detectable by transesophageal echocardiography already at the end of surgery. Though long-term results using this new method are not yet available, the initial promising results postoperatively are encouraging toward true one-stage repair by combining classic aortic surgery with open antegrade stent grafting utilizing the newly designed hybrid prosthesis. While surgical trauma is markedly reduced, this treatment option can be offered to elderly patients as well.

Administration of C1-esterase inhibitor during emergency coronary artery bypass surgery in acute ST-elevation myocardial infarction☆

OBJECTIVE

Myocardial inflammatory response including complement activation was demonstrated as an important mechanism of ischemia-reperfusion injury and complement inhibition by C1-esterase inhibitor (C1-INH) has recently shown to have cardioprotective effects in experimental and clinical settings.

METHODS

The effects of C1-INH on complement activation, myocardial cell injury, and clinical outcome were studied in patients undergoing emergency CABG due to acute ST-elevation myocardial infarction (STEMI) with (group 1, CABG+STEMI+C1-INH, n=28) and without (group 2, CABG+STEMI, n=29) bolus administration of C1-INH (40 IU kg(-1)) during reperfusion and 6 h postoperatively (20 IU kg(-1)) besides the same study protocol. C1-INH activity, C3c and C4 complement activation fragments, and cardiac troponin I (cTnI) were measured preoperatively and up to 48 h postoperatively and compared to another elective set of CABG patients without STEMI as controls (group 3, CABG-STEMI, n=10). Clinical data, adverse events, and patient outcome were recorded prospectively.

RESULTS

Patient characteristics were not different between groups 1 and 2. No drug-related adverse events were observed. Constant plasma levels of C1-INH were found in group 1, but not in groups 2 and 3. Plasma levels of C3c and C4 complement fragments were reduced in all three groups after surgery throughout the observation time, but tended to be lower in groups 1 and 2 compared with group 3. Preoperative cTnI levels were elevated but not different between the groups 1 and 2. The area under curve (AUC), as well as the postoperative cTnI serum levels, was significantly lower (P<0.05) in group 1 with a treatment delay < or = 6 h between reperfusion and symptom onset compared to group 2 at 36 h (47.9+/-11.1 ng/ml vs 97.7+/-17.2 ng/ml; mean+/-SEM), and 48 h (33.5+/-5.8 ng/ml vs 86.5+/-19.2 ng/ml) after surgery, but remained unchanged between groups among patients with a treatment delay of more than 6-24 h. In-hospital adverse events and postoperative complications, ICU and hospital stay, as well as in-hospital mortality (14.3% vs 13.8%; P=NS) were not different between groups 1 and 2.

CONCLUSIONS

C1-INH administration in emergency CABG with acute STEMI is safe and effective to inhibit complement activation and may reduce myocardial ischemia-reperfusion injury as measured by cTnI.

Prognostic Value of Preoperative Cardiac Troponin I in Patients Undergoing Emergency Coronary Artery Bypass Surgery With Non-ST-Elevation or ST-Elevation Acute Coronary Syndromes

BACKGROUND

Cardiac troponin I (cTnI) is a highly sensitive and specific biomarker which has been shown to predict patient outcome pre- and postoperatively following elective coronary artery bypass surgery (CABG). Whether preoperatively elevated cTnI levels similarly predict the outcome in patients undergoing emergency CABG with acute myocardial infarction (AMI) is currently unknown.

METHODS AND RESULTS

A possible correlation between preoperative cTnI and in-hospital mortality and major adverse cardiac events (MACE) was investigated in 57 patients with ST-elevation AMI (STEMI) in group 1 and 197 with Non-ST-elevation AMI (NSTEMI) in group 2, who were operated within 24 hours after onset of symptoms. Primary study end point was all-cause in-hospital mortality. Secondary end points were low cardiac output syndrome (LCOS) and hospital course. CTnI levels on admission were higher in group 1 compared with group 2 (7.1+/-1.8 versus 1.4+/-1.8 ng/mL; P<0.001). Overall in-hospital mortality was higher in group 1 compared with group 2 (14.3 versus 4.1%; odds ratio [OR], 3.9, 95% confidence interval [CI], 1.3 to 12.3; P<0.01). LCOS occurred in 16/57 (28.1%), and 18/197 (9.1%) patients, respectively (OR, 3.9, 95% CI, 1.7 to 8.8; P<0.001). Postoperative ventilation time, intensive care, and hospital stay were significantly longer in group 1 versus group 2. Multivariate logistic regression analyses revealed preoperative cTnI as the strongest independent predictor for in-hospital mortality (P<0.001) and MACE (P<0.001) in all AMI patients, regardless whether ST-elevation was included as an additional risk factor or not.

CONCLUSIONS

Preoperative cTnI measurement before emergency CABG appears as a powerful and independent determinant of in-hospital mortality and MACE in acute STEMI and NSTEMI.

Prognostic Significance of Multiple Previous Percutaneous Coronary Interventions in Patients Undergoing Elective Coronary Artery Bypass Surgery

Background— A possible relationship between increased perioperative risk during coronary artery bypass grafting (CABG) and previous percutaneous coronary intervention (PCI) is debatable. We sought to determine the impact of previous PCI on patient outcome after elective CABG.

Methods and Results— Between January 2000 and January 2005, 2626 consecutive patients undergoing first-time isolated elective CABG as the primary revascularization procedure (group 1) were evaluated for in-hospital mortality and major adverse cardiac events (MACEs) and were compared with 360 patients after single PCI (group 2) and with 289 patients after multiple PCI sessions (group 3) before elective CABG. Unadjusted univariate and risk-adjusted multivariate logistic-regression analysis revealed previous multiple PCIs to be strongly associated with in-hospital mortality (odds ratio [OR], 2.24; 95% confidence interval [CI], 1.52 to 3.21; P <0.001) and MACEs (OR, 2.28; 95% CI, 1.38 to 3.59; P <0.001). To control for selection bias, a computed propensity-score matching based on 13 patient characteristics and preoperative risk factors was performed separately comparing group 1 versus 2 and group 1 versus 3. After propensity matching, conditional logistic-regression analysis confirmed previous multiple PCIs to be strongly associated with in-hospital mortality (OR, 3.01; 95% CI, 1.51 to 5.98; P <0.0017) and MACEs (OR, 2.31; 95% CI, 1.45 to 3.67; P <0.0004).

Conclusions— In patients with a history of multiple PCI sessions, perioperative risk for in-hospital mortality and MACEs during subsequent elective CABG is increased.

Tacrolimus pharmacokinetics in lung transplantation: new strategies for monitoring

BACKGROUND

Tacrolimus (TAC) dosing in lung transplantation is traditionally based on blood trough levels (C0). The best sampling strategy for the estimation of total drug exposure (area-under-the-curve [AUC]) has not been determined.

METHODS

Thirty-one 12-hour pharmacokinetic profiles were studied in 15 patients (8 men and 7 women, 42.0 +/- 13 years) post-bilateral lung transplantation (7.3 +/- 3.7 months; range, 3-18 months). Twelve-hour AUC (AUC0-12) was calculated by trapezoidal rule. Relationships between individual concentration points or abbreviated kinetics (2-4 concentration points) and AUC0-12 were determined by linear regression analysis (R2; absolute prediction error [APE]).

RESULTS

Pharmacokinetic profiles showed high variability, particularly in the absorption phase. AUC was 221 +/- 47.2 ng/ml (range, 156-329.3 ng/ml) at C0 10 to 15 ng/ml and was independent of TAC dose (R2 = 0.002). C0 was poorly predictive of AUC0-12 (R2 = 0.64; APE, 16.1% +/- 10.9%; range, 1.4%-37.8%). The predictive performance for AUC0-12 was highest with abbreviated kinetics using 4 (C0/C2/C3/C4: R(2) = 0.99; APE, 2.6% +/- 2.0%; range, 0.1%-7%) or 3 concentration points (C0/C2/C4: R2 = 0.98; APE, 2.6% +/- 2.1%; range, 0.1%-9.1%). Of the 2-point kinetics C2/C6 (R2 = 0.96; APE, 5.3% +/- 3.7%; range, 0.1%-12.7%), C2/C4 (R2 = 0.94, APE 6.7% +/- 4.8%; range 0.1%-14.6%) and C0/C4 (R2 = 0.94; APE 4.1% +/- 2.9%; range, 0.5%-11.4%) performed best. Single point strategies (best was C4: R2 = 0.94; APE 7.1% +/- 5.5%, range, 0.2%-24.1%) all had unacceptably high APE (range > 15%).

CONCLUSION

True TAC exposure shows high variability in stable lung transplant patients and is poorly predicted by C0. Abbreviated kinetics covering at least 2 concentration points between 0 and 4 hours post-drug intake are required for an accurate estimation of AUC.

Prognostic value of preoperative cardiac troponin I in patients with non-ST-segment elevation acute coronary syndromes undergoing coronary artery bypass surgery

STUDY OBJECTIVES

Elevated levels of cardiac troponin I (cTnI) have been associated with adverse short-term and long-term outcomes in acute coronary syndrome (ACS) patients and in patients who underwent coronary artery bypass grafting (CABG); however, the prognostic implications of preoperative cTnI determination have not been investigated so far.

DESIGN AND SETTING

Retrospective study in a department of cardiothoracic surgery of a university hospital.

PATIENTS AND METHODS

A possible correlation between preoperative cTnI levels and major adverse cardiac events (MACE) and in-hospital mortality in CABG patients with non-ST-segment elevation ACS (NSTE-ACS) was investigated. cTnI was determined in 1,978 of 3,124 consecutive CABG patients. Among these, 1,592 patients had preoperative cTnI levels < 0.1 ng/mL and therefore served as control subjects (group 1), 265 patients had NSTE-ACS with cTnI levels from 0.11 to 1.5 ng/mL (group 2), and 121 patients had NSTE-ACS with cTnI levels > 1.5 ng/mL (group 3). cTnI levels, clinical data, MACE, and in-hospital mortality were recorded prospectively. Logistic regression and receiver operating characteristic analyses were applied to determine prognostic cutoff values of cTnI.

RESULTS

Perioperative myocardial infarction was found in 5.8% of the patients in group 1, 8.3% of the patients in group 2 (odds ratio [OR], 1.5; 95% confidence interval [CI], 0.9 to 2.5), and 18.2% patients in group 3 (OR, 3.6; 95% CI, 2.1 to 6.2; p < 0.0001, Cochran-Armitage trend test). Low cardiac output syndrome occurred in 1.5% of patients in group 1, 4.2% of patients in group 2 (OR, 2.8; 95% CI, 1.3 to 6.1), and 10.9% patients in group 3 (OR, 6.5; 95% CI, 2.9 to 14.4; p < 0.0001). In-hospital mortality was 1.5% in group 1, 3.0% in group 2 (OR, 2.0; 95% CI, 0.8 to 4.8), but 6.6% in group 3 (OR, 4.6; 95% CI, 1.9 to 11.1; p < 0.0001). Univariate and multivariate logistic regression analyses identified cTnI as the strongest preoperative predictor for MACE and in-hospital mortality, respectively.

CONCLUSIONS

Preoperative cTnI measurement before CABG appears as a powerful and independent determinant of short-term surgical risk in patients with NSTE-ACS.

Diagnostic discrimination between graft-related and non-graft-related perioperative myocardial infarction with cardiac troponin I after coronary artery bypass surgery

AIMS

The rise of markers for myocardial injury indicates early graft-related or non-graft-related perioperative myocardial infarction (PMI) after coronary artery bypass grafting (CABG). A diagnostic discrimination between these two situations may enable adequate therapeutic measures, limiting myocardial damage, and improving outcome.

METHODS AND RESULTS

In a prospective study, 94 among 3308 consecutive CABG patients underwent acute reangiography because of evidence of PMI. Of these 94 patients, 56 had graft-related PMI (group 1), 38 patients had non-graft-related PMI (group 2), and 95 patients without evidence of PMI and angiographically patent grafts served as control (group 3). Cardiac troponin I (cTnI), creatine kinase (CK), and its MB fraction were determined. CTnI, but not CK/CK-MB levels were significantly higher in group 1 than in groups 2 and 3 at 12 and 24 h after aortic unclamping (P<0.0001). Receiver operating characteristic and multivariable logistic regression analyses indicated cTnI as the best discriminator between PMI 'in general' and 'inherent' release of cTnI after CABG with a cut-off value of 10.5 ng/mL and between graft-related and non-graft-related PMI with a cut-off value of 35.5 ng/mL.

CONCLUSION

Perioperative cTnI elevation after CABG separates among patients with graft-related, non-graft-related, and without PMI, however, not earlier than 12 h after surgery.

In vivo effects of hypothermia on the microcirculation during extracorporeal circulation

OBJECTIVE

Induced hypothermia has been shown to be protective during cardiac surgery, but also in traumatic, ischemic, burn, and neurological injury. In previous in vivo animal experiments, we documented increased leukocyte/endothelial (L/E) cell interaction following normothermic extracorporeal blood circulation (ECC). This study was carried out to investigate whether reduced core temperature during ECC affects the damage to the microcirculation as evidenced by leukocyte adherence and edema formation.

METHODS

Intravital fluorescence microscopy was used on the dorsal skinfold chamber preparation in Syrian golden hamsters. ECC was introduced via a micro-rollerpump (1 ml/min) and a 60 cm silicon tube (1mm inner diameter) shunted between the carotid artery and the jugular vein after application of 300IE Heparin/kg per body weight. Experiments were performed in chronically instrumented, awake animals (age 10-14 weeks, weight 65-75 g). Animals of the experimental group were cooled to 18 degrees C body temperature while ECC, followed by a rewarming period (n=7), controls experienced ECC under normothermia (37 degrees C, n=7).

RESULTS

30 min ECC at 18 degrees C resulted in a decrease of rolling and adherent leucocytes (stickers) in postcapillary venules after 1, 4 and 8h compared with the control group (119+/-46 vs. 274+/-113 n/mm2, P<0.05, mean+/-SD; n=7 in each group). Functional capillary density was significantly reduced during hypothermia (80+/-16 vs. 148+/-16 cm/cm2, P<0.05), but restored after rewarming. In contrast, edema formation was markedly increased during hypothermia.

CONCLUSIONS

Hypothermia during ECC significantly reduced L/E cell interaction in the early post-ECC period. Hypothermia markedly reduced microvascular perfusion, but was completely restored upon rewarming. Despite a reduced number of adherent leukocytes, no protection of endothelial barrier function was seen as a consequence of induced hypothermia.

Paradoxical attenuation of leukocyte rolling in response to ischemia- reperfusion and extracorporeal blood circulation in inflamed tissue

In contrast to acute preparations such as the exteriorized mesentery or the cremaster muscle, chronically instrumented chamber models allow one to study the microcirculation under “physiological” conditions, i.e., in the absence of trauma-induced leukocyte rolling along the venular endothelium. To underscore the importance of studying the naive microcirculation, we implanted titanium dorsal skinfold chambers in hamsters and used intravital fluorescence microscopy to study venular leukocyte rolling in response to ischemia-reperfusion injury or extracorporeal blood circulation. The experiments were performed in chambers that fulfilled all well-established criteria for a physiological microcirculation as well as in chambers that showed various extents of leukocyte rolling due to trauma, hemorrhage, or inflammation. In ideal chambers with a physiological microcirculation (<30 rolling leukocytes/mm vessel circumference in 30 s), ischemia-reperfusion injury and extracorporeal blood circulation significantly stimulated leukocyte rolling along the venular endothelium and, subsequently, firm leukocyte adhesion. In contrast, both stimuli failed to elicit leukocyte rolling in borderline chambers (30–100 leukocytes/mm), and in blatantly inflamed chambers with yet higher numbers of rolling leukocytes at baseline (>100 leukocytes/mm), we observed a paradoxical reduction of leukocyte rolling after ischemia-reperfusion injury or extracorporeal blood circulation. A similar effect was observed when we superfused leukotriene B4 (LTB4) onto the chamber tissue. The initial increase in leukocyte rolling in response to an LTB4 challenge was reversed by a second superfusion 90 min later. These observations underscore 1) the benefit of studying leukocyte-endothelial cell interaction in chronically instrumented chamber models and 2) the necessity to strictly adhere to well-established criteria of a physiological microcirculation.