Multiorgan recovery in a cadaver body using mild hypothermic ECMO treatment in a murine model

BACKGROUND

Transplant candidates on the waiting list are increasingly challenged by the lack of organs. Most of the organs can only be kept viable within very limited timeframes (e.g., mere 4-6 h for heart and lungs exposed to refrigeration temperatures ex vivo). Donation after circulatory death (DCD) using extracorporeal membrane oxygenation (ECMO) can significantly enlarge the donor pool, organ yield per donor, and shelf life. Nevertheless, clinical attempts to recover organs for transplantation after uncontrolled DCD are extremely complex and hardly reproducible. Therefore, as a preliminary strategy to fulfill this task, experimental protocols using feasible animal models are highly warranted. The primary aim of the study was to develop a model of ECMO-based cadaver organ recovery in mice. Our model mimics uncontrolled organ donation after an "out-of-hospital" sudden unexpected death with subsequent "in-hospital" cadaver management post-mortem. The secondary aim was to assess blood gas parameters, cardiac activity as well as overall organ state. The study protocol included post-mortem heparin-streptokinase administration 10 min after confirmed death induced by cervical dislocation under full anesthesia. After cannulation, veno-arterial ECMO (V-A ECMO) was started 1 h after death and continued for 2 h under mild hypothermic conditions followed by organ harvest. Pressure- and flow-controlled oxygenated blood-based reperfusion of a cadaver body was accompanied by blood gas analysis (BGA), electrocardiography, and histological evaluation of ischemia-reperfusion injury. For the first time, we designed and implemented, a not yet reported, miniaturized murine hemodialysis circuit for the treatment of severe hyperkalemia and metabolic acidosis post-mortem.

RESULTS

BGA parameters confirmed profound ischemia typical for cadavers and incompatible with normal physiology, including extremely low blood pH, profound negative base excess, and enormously high levels of lactate. Two hours after ECMO implantation, blood pH values of a cadaver body restored from < 6.5 to 7.3 ± 0.05, pCO2 was lowered from > 130 to 41.7 ± 10.5 mmHg, sO2, base excess, and HCO3 were all elevated from below detection thresholds to 99.5 ± 0.6%, - 4 ± 6.2 and 22.0 ± 6.0 mmol/L, respectively (Student T test, p < 0.05). A substantial decrease in hyperlactatemia (from > 20 to 10.5 ± 1.7 mmol/L) and hyperkalemia (from > 9 to 6.9 ± 1.0 mmol/L) was observed when hemodialysis was implemented. On balance, the first signs of regained heart activity appeared on average 10 min after ECMO initiation without cardioplegia or any inotropic and vasopressor support. This was followed by restoration of myocardial contractility with a heart rate of up to 200 beats per minute (bpm) as detected by an electrocardiogram (ECG). Histological examinations revealed no evidence of heart injury 3 h post-mortem, whereas shock-specific morphological changes relevant to acute death and consequent cardiac/circulatory arrest were observed in the lungs, liver, and kidney of both control and ECMO-treated cadaver mice.

CONCLUSIONS

Thus, our model represents a promising approach to facilitate studying perspectives of cadaveric multiorgan recovery for transplantation. Moreover, it opens new possibilities for cadaver organ treatment to extend and potentiate donation and, hence, contribute to solving the organ shortage dilemma.

The completeness of the left atrial appendage amputation during routine cardiac surgery

BACKGROUND

Left atrial appendage (LAA) is the origin of most heart thrombi which can lead to stroke or other cerebrovascular event in patients with non-valvular atrial fibrillation (AF). This study aimed to prove safety and low complication rate of surgical LAA amputation using cut and sew technique with control of its effectiveness.

METHODS

303 patients who have undergone selective LAA amputation were enrolled in the study in a period from 10/17 to 08/20. The LAA amputation was performed concomitant to routine cardiac surgery on cardiopulmonary bypass with cardiac arrest with or without previous history of AF. The operative and clinical data were evaluated. Extent of LAA amputation was examined intraoperatively by transoesophageal echocardiography (TEE). Six months in follow up, the patients were controlled regarding clinical status and episodes of strokes.

RESULTS

Average age of study population was 69.9 ± 19.2 and 81.9% of patients were male. In only three patients was residual stump after LAA amputation larger than 1 cm with average stump size 0.28 ± 0.34 cm. 3 patients (1%) developed postoperative bleeding. Postoperatively 77 (25.4%) patients developed postoperative AF (POAF), of which 29 (9.6%) still had AF at discharge. On 6 months follow up only 5 patients had NYHA class III and 1 NYHA class IV. Seven patients reported with leg oedema and no patient experienced any cerebrovascular event in early postoperative follow up.

CONCLUSION

LAA amputation can be performed safely and completely leaving minimal to no LAA residual stump.

First clinical experience with the novel cold storage SherpaPak™ system for donor heart transportation

Background

The current gold standard for donor heart preservation is a three-bag-technique and storage in a cooler filled with slush ice. This technique can cause freezing injury with protein denaturation. We report our early experience with a single-use disposable device (SherpaPak™, Paragonix Technologies, MA, USA) specifically designed for sterile permanent temperature-controlled transportation of donor hearts.

Methods

In this case control study with 2:1 matching we identified 21 patients after heart transplantation depending on type of organ transport (standard three-bag-technique vs. SherpaPak™). The outcome after donor heart storage in the SherpaPak™ was compared with donor heart transportation with the standard technique.

Results

Since July 2018 seven patients (5 males; mean age 50.3±13.2years) underwent heart transplantation with the SherpaPak™ system. Cold ischemic time was longer in the SherpaPak™ group (207.7±23.3 vs. 181.6±21.9, P=0.027). SherpaPak™ kept the organ temperature at 5.1±0.8 °C, with an average outside temperature of 21.4±3.6 °C. Among all 21 transplanted patients four developed fatal early graft failure (28.6% vs. 21.4%, P=0.432). Over the first hours we noticed no difference in hemodynamic parameters, CK-MB levels or vasoactive-inotropic score. During first follow-up we noticed slightly better right heart function in the SherpaPak™ group (TAPSE 17.83±2.71 vs. 14.52±2.61 mm, P=0.020). We identified no positive blood cultures in the SherpaPak™ group within the first 30 days after heart transplantation.

Conclusions

The SherpaPak™ provides a constant temperature during transportation with permanent monitoring, never dropping below 4 °C. Organs transported with this novel device showed a normal perioperative function.

Venovenous extracorporeal membrane oxygenation for the management of contralateral iatrogenic bronchus perforation during lower bilobectomy

Tracheobronchial rupture by a double-lumen endobronchial tube is a rare but life-threatening complication. We report a case of bronchial rupture during contralateral bilobectomy. Venovenous extracorporeal membrane oxygenation support was instituted via the right femoral vein and the internal jugular vein with the patient in the left lateral decubitus position. Sleeve resection of the ruptured bronchus was performed. The patient was successfully discharged home. Rapid institution of venovenous extracorporeal membrane oxygenation is helpful to manage this intraoperative complication.

HO-1 concentrations 24 hours after cardiac surgery are associated with the incidence of acute kidney injury: a prospective cohort study

Background

Acute kidney injury (AKI) is a serious complication after cardiac surgery that is associated with increased mortality and morbidity. Heme oxygenase-1 (HO-1) is an enzyme synthesized in renal tubular cells as one of the most intense responses to oxidant stress linked with protective, anti-inflammatory properties. Yet, it is unknown if serum HO-1 induction following cardiac surgical procedure involving cardiopulmonary bypass (CPB) is associated with incidence and severity of AKI.

Patients and methods

In the present study, we used data from a prospective cohort study of 150 adult cardiac surgical patients. HO-1 measurements were performed before, immediately after and 24 hours post-CPB. In univariate and multivariate analyses, the association between HO-1 and AKI was investigated.

Results

AKI with an incidence of 23.3% (35 patients) was not associated with an early elevation of HO-1 after CPB in all patients (P=0.88), whereas patients suffering from AKI developed a second burst of HO-1 24 hours after CBP. In patients without AKI, the HO-1 concentrations dropped to baseline values (P=0.031). Furthermore, early HO-1 induction was associated with CPB time (P=0.046), while the ones 24 hours later lost this association (P=0.219).

Conclusion

The association of the second HO-1 burst 24 hours after CBP might help to distinguish between the causality of AKI in patients undergoing CBP, thus helping to adapt patient stratification and management.

The COMT-polymorphism is not associated with the incidence of acute kidney injury after cardiac surgery - a prospective cohort study

Background

The Catechol-O-methyltransferase (COMT) represents the key enzyme in catecholamine degradation. Recent studies suggest that the COMT rs4680 polymorphism is associated with the response to endogenous and exogenous catecholamines. There are, however, conflicting data regarding the COMT Met/Met phenotype being associated with an increased risk of acute kidney injury (AKI) after cardiac surgery. The aim of the current study is to prospectively investigate the impact of the COMT rs4680 polymorphism on the incidence of AKI in patients undergoing cardiac surgery.

Methods

In this prospective single center cohort study consecutive patients hospitalized for elective cardiac surgery including cardiopulmonary-bypass (CPB) were screened for participation. Demographic clinical data, blood, urine and tissue samples were collected at predefined time points throughout the clinical stay. AKI was defined according to recent recommendations of the Kidney Disease Improving Global Outcome (KDIGO) group. Genetic analysis was performed after patient enrolment was completed.

Results

Between April and December 2014, 150 patients were recruited. The COMT genotypes were distributed as follows: Val/Met 48.7%, Met/Met 29.3%, Val/Val 21.3%. No significant differences were found for demography, comorbidities, or operative strategy according to the underlying COMT genotype. AKI occurred in 35 patients (23.5%) of the total cohort, and no differences were evident between the COMT genotypes (20.5% Met/Met, 24.7% Val/Met, 25.0% Val/Val, p = 0.66). There were also no differences in the post-operative period, including ICU or in-hospital stay.

Conclusions

We did not find statistically significant variations in the risk for postoperative AKI, length of ICU or in-hospital stay according to the underlying COMT genotype.

TIMP-2*IGFBP7 (Nephrocheck®) Measurements at Intensive Care Unit Admission After Cardiac Surgery are Predictive for Acute Kidney Injury Within 48 Hours

BACKGROUND/AIMS

Acute kidney injury (AKI) is a postoperative complication after cardiac surgery with a high impact on mortality and morbidity. Nephrocheck® [TIMP-2*IGFBP7] determines markers of tubular stress, which occurs prior to tubular damage. It is unknown at which time-point [TIMP-2*IGFBP7] measurement should be performed to ideally predict AKI. We investigated the association of [TIMP-2*IGFBP7] at various time-points with the incidence of AKI in patients undergoing elective cardiac surgery including cardio-pulmonary bypass.

METHODS

In a prospective cohort study, serial blood and urine samples were collected from 150 patients: pre-operative, at ICU-admission, 24h and 48h post-surgery. AKI was defined as Serum-Creatinine rise >0.3 mg/dl within 48hrs. Urinary [TIMP-2*IGFBP7] was measured at pre-operative, ICU-admission and 24h post-surgery; medical staff was kept blinded to these results.

RESULTS

A total of 35 patients (23.5%) experienced AKI, with a higher incidence in those with high [TIMP-2*IGFBP7] values at ICU admission (57.1% vs. 10.1%, p<0.001). In logistic regression [TIMP-2*IGFBP7] at ICU admission was independently associated with the occurrence of AKI (Odds Ratio 11.83; p<0.001, C-statistic= 0.74) after adjustment for EuroSCORE II and CBP-time.

CONCLUSIONS

Early detection of elevated [TIMP-2*IGFBP7] at ICU admission was strongly predictive for postoperative AKI and appeared to be more precise as compared to subsequent measurements.

Secondary sclerosing cholangitis in cardiac surgical patients: A complication with a dismal prognosis

OBJECTIVES

Secondary sclerosing cholangitis in critically ill patients is a rapidly progressing disease leading to biliary fibrosis and cirrhosis. We describe the course of sclerosing cholangitis in critically ill patients after cardiac surgery and compare this with matched patients.

METHODS

A retrospective search for "secondary sclerosing cholangitis" and "liver and/or hepatic failure" in all adult patients (aged 18-93 years) who underwent cardiac surgery from April 2007 to March 2016 identified 192 of 8625 patients. Of those, 12 were diagnosed with sclerosing cholangitis in critically ill patients (incidence, 0.14%). A 3:1 matching was performed. Laboratory values, pharmacologic requirements, ventilation times, mechanical circulatory support, and endoscopic retrograde cholangiopancreatography studies were extracted from the hospital database.

RESULTS

A total of 9 men and 3 women were affected (age 71 years; range, 59.8-75.5 years). Critically ill patients with sclerosing cholangitis required vasoconstrictors and inotropes longer than control patients (norepinephrine 356.5 hours [264.5-621] vs 68 hours [15-132.5], P = .003; enoximone 177 hours [124.3-249.5] vs 48.5 hours [12-81 hours], P < .001, respectively). Critically ill patients with sclerosing cholangitis had longer intubation time (628.5 hours [377.3-883] vs 25 hours [9.8-117.5]; P < .001) and more surgical revisions (3 [2.5-6] vs 1 [0-2], P = .003) than the matching group. Bilirubin (23.3 mg/dL [14.4-32.9] vs 1 mg/dL [0.6-2.7]; P < .001), gamma-glutamyltransferase (1082.3 U/L [259.5-2265.7] vs 53.8 U/L [35.1-146]; P < .001), and alkaline phosphatase (751.5 U/L [372-1722.3] vs 80.5 U/L [53.3-122]; P < .001) were higher in critically ill patients with sclerosing cholangitis. One critically ill patient with sclerosing cholangitis underwent successful liver transplantation. A total of 11 patients sclerosing cholangitis died (92%) versus 12 patients (33%, P < .001) in the control group.

CONCLUSIONS

Sclerosing cholangitis in critically ill patients is a fatal complication in patients undergoing cardiac surgery who have a complicated postoperative course with prolonged vasoconstrictor, inotropic, and respiratory therapy, or who require frequent surgical revisions. Liver transplantation remains the only curative option but is often precluded by the age and critical state of patients undergoing cardiac surgery.

Cardiac Surgery is Safe in Female Patients with a History of Breast Cancer

PURPOSE

In cardiac surgery candidates, a concomitant history of breast cancer suggests adverse outcomes. The possibility of internal mammary artery (IMA) utilization and its patency rate is frequently discussed. Secondary, blood loss and wound related infections might be important issues. However, publications focusing on these issues are limited.

METHODS

We analyzed 32 patients with previously treated breast cancer undergoing cardiac bypass (CABG) and combined CABG surgery matched to 99 control subjects in a retrospective cohort study. Patients were analyzed regarding IMA utilization, blood loss and substitution and frequent perioperative complications as well as long-term mortality.

RESULTS

No significant differences between groups were observed regarding duration of surgery, IMA-utilization, incidence of infections and postoperative complications or mortality. A pronounced decline of hemoglobin/hematocrit was evident within the first 6 postoperative hours (3.3 ± 1.8 vs. 2.5 ± 1.8 mg/dl; p = 0.03) in breast cancer patients not related to an increased drainage loss but associated with an increase of international normalized ratio (INR) (0.39 ± 0.16 vs. 0.29 ± 0.24; p <0.01).

CONCLUSION

In breast cancer patients, CABG and combined CABG procedures can safely be performed with comparable short- and long-term results.

Impact of levosimendan and ischaemia-reperfusion injury on myocardial subsarcolemmal mitochondrial respiratory chain, mitochondrial membrane potential, Ca2+ cycling and ATP synthesis

OBJECTIVES

Levosimendan (LS) is increasingly used in case of myocardial failure after cardiac surgery. The impact of LS on myocardial mitochondrial functions, such as respiratory chain function (RCF), mitochondrial membrane potential (ΔΨm), Ca(2+) handling, mitochondrial permeability transition pore (mPTP) opening and ATP during ongoing ischaemia/reperfusion (IR) injury, is not well understood. Depending on LS, I/R injury or the combination of both, we analysed myocardial functions in a retrograde Langendorff-model followed by the analysis of subsarcolemmal mitochondrial (SSM) functions.

METHODS

Rat hearts were divided into four study groups; two were subjected to 30 min of perfusion without (control) or with the application of 1.4 µmol/20 min LS (Levo). Experiments were repeated with hearts being subjected to 40 min of normothermic stop-flow ischaemia and 30 min of reperfusion without (IR) or with LS application (Levo-IR). Systolic left ventricular pressure (LVPsys), left ventricular contractility (LVdp/dtmax) and coronary flow were determined. SSM were analysed regarding RCF, ΔΨm, ATP, and Ca(2+) retention capacity (CRC), Ca(2+)-induced swelling and Ca(2+) fluxes after (re)perfusion.

RESULTS

I/R injury suppressed LVdp/dtmax (1381 ± 927 vs 2464 ± 913 mmHg/s; P = 0.01 at 30 min (re-)perfusion time). IR revealed complex I-V state3 (19.1 ± 7.4 vs 27.6 ± 11.0 nmolO2/min; P < 0.044) and II-V state3 (20.6 ± 6.8 vs 37.3 ± 9.10 molO2/min; P < 0.0001) suppression and Levo limited I-V (14.8 ± 11.1 vs 27.6 ± 11.0 nmolO2/min; P < 0.001) and II-V (24.1 ± 6.4 vs 37.3 ± 9.10 molO2/min; P < 0.0001) function. After energizing, ΔΨm hypopolarization was observed in Levo (0.76 ± 0.04 vs 0.84 ± 0.04; P = 0.02), IR (0.75 ± 0.06 vs 0.84 ± 0.04; P = 0.007) and Levo-IR (0.75 ± 0.06 vs 0.06 ± 0.04; P = 0.01). IR (AUC: 626 vs 292; P = 0.023) and Levo-IR (AUC: 683 vs 292, P = 0.003) increased Ca(2+)-induced mPTP-opening susceptibility. CRC declined in IR (6.4 ± 2.1 vs 10.5 ± 2.6; P = 0.04) or Levo (6.5 ± 2.0 vs 10.5 ± 2.6; P = 0.023). Ca(2+) uptake was delayed in IR and Levo-IR without LS impact (P < 0.0001). Ca(2+) liberation was increased in Levo-IR. ATP synthesis was reduced in Levo (0.49 ± 0.14 vs 0.74 ± 0.14; P = 0.002) and Levo-I/R (0.34 ± 0.18 vs 0.74 ± 0.14; P < 0.002).

CONCLUSION

LS limited RCF at complex IV and V with ΔΨm hypopolarization suggesting a specific [Formula: see text]-dependent pathway. Ca(2+) redistribution from SSM by LS during I/R injury possibly prevents from Ca(2+) overload due to mPTP flickering. LS-induced mPTP flickering did not promote permanent Ca(2+)-induced mPTP opening. LS-dependent inhibition of ATP generation presumably resulted from complex IV and V limitations and lowered ΔΨm. However, a resulting impact of limited ATP synthesis on myocardial recovery remains arguable.

A multicentre evaluation of the autograft procedure for young patients undergoing aortic valve replacement: update on the German Ross Registry†

OBJECTIVES

Conventional aortic valve replacement (AVR) in young, active patients represents a suboptimal solution in terms of long-term survival, durability and quality of life. The aim of the present work is to present an update on the multicentre experience with the pulmonary autograft procedure in young, adult patients.

METHODS

Between 1990-2013, 1779 adult patients (1339 males; 44.7 ± 11.6 years) underwent the pulmonary autograft procedure in 8 centres. All patients underwent prospective clinical and echocardiographic examinations annually. The mean follow-up was 8.3 ± 5.1 years (range 0-24.3 years) with a total cumulative follow-up of 14 288 years and 662 patients having a follow-up of at least 10 years.

RESULTS

The early (30-day) mortality rate was 1.1% (n = 19). Late (>30 day) survival of the adult population was comparable with the age- and gender-matched general population (observed deaths: 101, expected deaths: 91; P = 0.29). Freedom from autograft reoperation at 5, 10 and 15 years was 96.8, 94.7 and 86.7%, respectively, whereas freedom from homograft reoperation was 97.6, 95.5 and 92.3%, respectively. The overall freedom from reoperation was 94.9, 91.1 and 82.7%, respectively. Longitudinal modelling of functional valve performance revealed a low (<5%) probability of a patient being in higher autograft regurgitation grades throughout the first decade. Similarly, excellent homograft function was observed throughout the first 15 years.

CONCLUSION

The autograft principle results in postoperative long-term survival comparable with that of the age- and gender-matched general population and reoperation rates within the 1%/patient-year boundaries and should be considered in young, active patients who want to avoid the shortcomings of conventional prostheses.

Preoperative serum h-FABP concentration is associated with postoperative incidence of acute kidney injury in patients undergoing cardiac surgery

Background

Fatty acid binding protein (FABP) is an intracellular transport protein associated with myocardial damage size in patients undergoing cardiac surgery. Furthermore, elevated FABP serum concentrations are related to a number of common comorbidities, such as heart failure, chronic kidney disease, diabetes mellitus, and metabolic syndrome, which represent important risk factors for postoperative acute kidney injury (AKI). Data are lacking on the association between preoperative FABP serum level and postoperative incidence of AKI.

Methods

This prospective cohort study investigated the association between preoperative h-FABP serum concentrations and postoperative incidence of AKI, hospitalization time and length of ICU treatment. Blood samples were collected according to a predefined schedule. The AKI Network definition of AKI was used as primary endpoint. All associations were analysed using descriptive and univariate analyses.

Results

Between 05/2009 and 09/2009, 70 patients undergoing cardiac surgery were investigated. AKI was observed in 45 patients (64%). Preoperative median (IQR) h-FABP differed between the AKI group (2.9 [1.7–4.1] ng/ml) and patients without AKI (1.7 [1.1–3.3] ng/ml; p = 0.04), respectively. Patients with AKI were significantly older. No statistically significant differences were found for gender, type of surgery, operation duration, CPB-, or X-Clamp time, preoperative cardiac enzymes, HbA1c, or CRP between the two groups. Preoperative h-FABP was also correlated with the length of ICU stay (r_s = 0.32, p = 0.007).

Conclusions

We found a correlation between preoperative serum h-FABP and the postoperative incidence of AKI. Our results suggest a potential role for h-FABP as a biomarker for AKI in cardiac surgery.

[Indications, risk factors, specialities and after-care of surgical treatment for cardiac and thoracic vascular diseases]

Despite a known high risk and complexity in the operative therapy of cardio-thoracic patients, cardiac surgery is medical routine activity today. The German Society of Cardiothoracic Surgery regularly analyses the more than 100.000 cases a year in Germany. Fixing procedural statics, it gives us the knowledge of individual risk factors and success rates for surgical therapy of our patients.Following we want to shortly summarize indications, risk factors, specialities and after-care of surgical treatment for cardiac and thoracic vascular diseases in adults.

Cardiac surgery in cases of myeloproliferative neoplasm: risk factor for stroke

Objectives: a history of myeloproliferative neoplasms is considered to increase the risks in cardiac surgery. In patients with myeloproliferative neoplasms, increased rates of perioperative infections and thromboembolic complications are suspected, but studies analyzing the impact of myeloproliferative neoplasms on results after cardiac surgery are lacking.

Methods: 13 patients with the diagnosis of myeloproliferative neoplasm underwent cardiac surgery. These patients were matched to 36 controls. Matching criteria consisted of sex, age, diagnosis, and comorbidities. Patients were analyzed regarding laboratory parameters, blood transfusion demands, morbidity, and mortality.

Results: compared to controls, patients with myeloproliferative neoplasms demonstrated a significantly lower body-mass index ( p < 0.01), creatinine ( p = 0.024), prothrombin time ( p = 0.001), and urea level ( p = 0.012). The perioperative leukocyte response ( p = 0.03) was ameliorated, and platelet counts ( p < 0.02) increased. Patients with myeloproliferative neoplasms had a reduced need for erythrocyte concentrates (54% vs. 86%, p = 0.047) but increased need for plasma and thrombocytes (15% vs. 0%, p = 0.07). Patients with myeloproliferative neoplasms had a significantly increased incidence of thromboembolic events compared to controls (31% vs. 3%, p = 0.014). Hospital mortality remained at zero, but mid-term survival was lower in patients with myeloproliferative neoplasms ( p = 0.078).

Conclusions: myeloproliferative neoplasm as a concomitant diagnosis increases the risk of thromboembolic complications during cardiac surgery. Plasma and platelet substitutions have to be administered, although strokes were not associated with hemostatic treatment.

Glutathione preconditioning ameliorates mitochondria dysfunction during warm pulmonary ischemia-reperfusion injury

OBJECTIVES

Reduced glutathione (GSH) has been shown to improve pulmonary graft preservation. Mitochondrial dysfunction is regarded to be the motor of ischemia-reperfusion injury (IR) in solid organs. We have shown previously that IR induces pulmonary mitochondrial damage. This study elucidates the impact of GSH preconditioning on the integrity and function of pulmonary mitochondria in the setting of warm pulmonary IR.

METHODS

Wistar rats were subjected to control, sham, and to two-study-group conditions (IR30/60 and GSH-IR30/60) receiving IR with or without GSH preconditioning. Rats were anesthetized and received mechanical ventilation. Pulmonary in situ clamping followed by reperfusion generated IR. Mitochondria were isolated from pulmonary tissue. Respiratory chain complexes activities (I-IV) were analyzed by polarography. Mitochondrial viability (Ca2+-induced swelling) and membrane integrity (citrate synthase assay) were determined. Subcellular-fractional cytochrome C-content (Cyt C) was quantified by enzyme-linked immunosorbent assay (ELISA). Mitochondrial membrane potential (ΔΨm) was analyzed by fluorescence-activated cell sorting (FACS) after energizing and uncoupling. Inflammatory activation was determined by myeloperoxidase activity (MPO), matrix-metalloproteinase 9 (MMP-9) activity by gel zymography.

RESULTS

Pulmonary IR significantly reduced mitochondrial viability in combination with ΔΨm hyper-polarization. GSH preconditioning improved mitochondrial viability and normalized ΔΨm. Cyt C was reduced after IR; GSH protected from Cyt C liberation. Respiratory chain complex activities (I, II, III) declined during IR; GSH protected complex II function. GSH also protected from MMP-9 and neutrophil sequestration (P>.05).

CONCLUSIONS

GSH preconditioning is effective to prevent mitochondrial death and improves complex II function during IR, but not mitochondrial membrane stability. GSH-mediated amelioration of ΔΨm hyper-polarization appears to be the key factor of mitochondrial protection.

Glycine preconditioning to ameliorate pulmonary ischemia reperfusion injury in rats

This study examines the impact of glycine (Gly) preconditioning on ischemia reperfusion (IR)-induced pulmonary mitochondrial injury to research the previously, in pig lungs, demonstrated Gly-dependent amelioration of pulmonary IR injury. IR injury was induced in rat lungs by 30 min pulmonary hilum clamping followed by 60 min reperfusion time. Rats were subjected to controls, shams and two study groups (IR30/60, Gly-IR30/60) receiving 37.5 mg Gly i.v. or not before IR induction. The wet/dry-weight ratio, mitochondria viability (MV), membrane integrity (MI), respiratory chain complex (RCC) activities, mitochondrial membrane potential (ΔΨm) and cytochrome C (Cyt C) content were analysed. In IR30/60, RCC and MV were impaired; Cyt C loss and MI combined with matrix metalloproteinase-9 (MMP-9) activation and ΔΨm alteration were observed when compared with controls. In Gly-IR30/60, complex II function and mitochondrial viability were protected during IR, and MMP-9 activation combined with tissue-water content accumulation and ΔΨm alteration were ameliorated. Cyt C loss, mitochondrial membranes damage, tissue GSH oxidation or neutrophil sequestration was not extenuated in Gly-IR30/60. Gly ameliorates IR-associated mitochondrial dysfunction and decay of viability and normalizes ΔΨm but does not protect from Cyt C liberation and mitochondrial membrane damage. Our data suggest that the previously described effect of Gly preconditioning results at least partially from mitochondrial protection. A dose-finding study is necessary to improve results of Gly preconditioning.

Ischemia-reperfusion injury-induced pulmonary mitochondrial damage

BACKGROUND

Mitochondrial dysfunction is a key factor in solid organ ischemia-reperfusion (IR) injury. Impaired mitochondrial integrity predisposes to cellular energy depletion, free radical generation, and cell death. This study analyzed mitochondrial damage induced by warm pulmonary IR.

METHODS

Anesthetized Wistar rats received mechanical ventilation. Pulmonary clamping was followed by reperfusion to generate IR injury. Rats were subjected to control, sham, and to 2 study group conditions: 30 minutes of ischemia without reperfusion (IR30/0), or ischemia followed by 60 minutes of reperfusion (IR30/60). Pulmonary edema was quantified by wet/dry-weight ratio. Polarography determined activities of respiratory chain complexes. Mitochondrial viability was detected by using Ca(2+)-induced swelling, and integrity by citrate synthase assay. Enzyme-linked immunosorbent assay determined cytochrome C content. Mitochondrial membrane potential (ΔΨm) stability was analyzed by flow cytometry using JC1, inflammation by myeloperoxidase (MPO) activity, and matrix-metalloproteinase-9 (MMP-9) activity by gel zymography, respectively.

RESULTS

In IR30/60 rats, tissue water content was elevated from 80.6 % (sham) to 86.9%. After ischemia, ΔΨm showed hyperpolarization and rapid decline after uncoupling compared with controls. IR, but not ischemia alone, impaired respiratory chain function complexes I, II and III (p < 0.05). Mitochondrial viability (p < 0.001) and integrity (p < 0.01) was impaired after ischemia and IR, followed by mitochondrial cytochrome C loss (p < 0.05). Increased activation of MPO (p < 0.01) and MMP-9 (p < 0.001) was induced by reperfusion after ischemia.

CONCLUSIONS

Ischemia-related ΔΨm hyper-polarization induces reperfusion-associated mitochondrial respiratory chain dysfunction in parallel with tissue inflammation and degradation. Controlling ΔΨm during ischemia might reduce IR injury.

Cardiac operations in the presence of meningioma

BACKGROUND

We investigated the effect of concomitant intracranial meningiomas on perioperative and postoperative complications after cardiac operations. Also studied was the intraoperative and perioperative management and long-term outcome of such patients.

METHODS

We retrospectively evaluated 16 cardiac surgical patients with intracranial meningiomas between January 1996 and July 2007. Neurologic outcome, incidence of transient neurologic deficits, and long-term follow-up focusing on freedom from any cardiac or neurosurgical intervention were assessed.

RESULTS

Five men and 11 women with a concomitant diagnosis of intracranial meningioma underwent cardiac operations using extracorporeal circulation. One patient received additional edema prophylaxis by intravenous dexamethasone. All patients were discharged home in good physical condition. Data on long-term survival were available on 14 patients, with 12 alive. Postoperatively, 2 patients died from myocardial infarction at 26.8 months and 2 from metastatic colon cancer at 57.9 months. Perioperative neurologic disorders were observed in 2 patients, comprising one stroke after intervention for aortic dissection and one thromboembolic event 2 weeks after biologic mitral valve replacement due to anticoagulation disorders. No meningioma-related adverse event was observed.

CONCLUSIONS

The presence of intracranial meningioma does not appear to be a risk factor for patients undergoing cardiac operations. No meningioma-related neurologic sequelae were documented postoperatively. Neurosurgical consultation should be obtained in all patients preoperatively.

Heterotopic rat heart transplantation (Lewis to F344): early ICAM-1 expression after 8 hours of cold ischemia

BACKGROUND

Primary graft dysfunction is a still poorly understood complication after cardiac transplantation. Ischemia/reperfusion injury contributes to different disorders resulting in impaired graft function.

METHODS

In a heterotopic rat heart transplantation model we extended graft ischemic time up to 8 hours.

RESULTS

Using immunohistochemistry we detected an up to 4-fold increase in intracellular adhesion molecule-1 (ICAM-1) expression during 4 hours of reperfusion, independent of ischemic time (30-minute ischemia: 7.65 +/- 2.15 without reperfusion, 19.46 +/- 4.6 after 4-hour reperfusion; 240-minute ischemia: 5.6 +/- 1.99 and 22.3 +/- 3.77; 480-minute ischemia: 3.7 +/- 1.56 and 13.1 +/- 2.2). Eight-hour ischemic allografts had an increase in CD8-positive cells (1.37 +/- 0.5 and 2.3 +/- 0.77) and a significant increase in MHC II expression (11.48 +/- 2.1 and 18.27 +/- 1.34) during 4 hours of reperfusion.

CONCLUSIONS

We hypothesize that these findings reflect an early inflammatory reaction in the allograft possibly triggered by oxidative stress. During therapeutic interventions, both of these pathways must be considered.

Impact of ascending aorta replacement combined with a Ross procedure on autograft root distensibility and function in patients with combined pathology of the aortic valve and ascending aorta

In this study we aimed to assess the autograft root dimensions, distensibility, and autograft valve function in patients after Ross operation combined with replacement of the ascending aorta compared to patients that underwent Ross operation only. Forty patients received a Ross operation, and in 12 of them an additional replacement of the ascending aorta was performed. Autograft root dimensions, distensibility, and valve function were assessed by echocardiography. There were no differences in root size, distensibility, and valve function between groups. Our preliminary results indicate that replacement of the ascending aorta with a noncompliant prosthesis has no effect on the autograft root.

Aortic valve replacement and coronary revascularization in paroxysmal nocturnal hemoglobinuria

Cardiac surgery in patients with paroxysmal nocturnal hemoglobinuria (PNH), which is an acquired hemolytic anemia associated with thrombocytopenia and an abnormal susceptibility to venous thromboses, requires special perioperative measures. PNH is based on a clonal defect of hematopoietic stem cells characterized by deficiency in glycosyl-phosphatidylinositol-anchored surface proteins. The major mechanism of hemolysis consists of unregulated complement activation. In cardiac surgery, PNH-induced granulocytopenia increases the risk of postoperative infection. PNH-induced complement activation is further exaggerated by extracorporeal circulation in cardiac surgery leading to putative hemolytic crisis. Here, we report on a patient who developed PNH after severe aplastic anemia undergoing aortic valve replacement and coronary revascularization using extracorporeal circulation and discuss the special perioperative management and the relevant literature on this issue. Special emphasis should be given to optimal preoperative patient preparation including G-CSF administration and red blood pack transfusions, perioperative platelet substitution, fluid management, and antibiotic prophylaxis.

The Innominate Vein as Alternative Venous Access for Complicated Implantable Cardioverter Defibrillator Revisions

BACKGROUND

Venous complications of implantable cardioverter defibrillator (ICD) systems may cause significant problems when the need for system revision or upgrades arises. Such revisions require venous access close to the site of the previous ICD implantation. The internal and external jugular vein have disadvantages due to a long subcutaneous course crossing the clavicle and problems with lead extraction if infection occurs.

METHODS

In seven patients with ICD revisions due to lead dysfunction (n = 4) and upgrade to a biventricular device (n = 2) and status after system removal due to infection with new device implantation (n = 1) conventional venous access could not be obtained. Intraoperative contrast venography demonstrated an occluded left subclavian and/or left innominate vein in all patients. In all patients, we gained venous access through puncture of the right innominate vein and tunneled the new lead subcutaneously to the ICD pocket on the left.

RESULTS

No intraoperative complications were observed. All patients are followed in our ICD clinic. Mean follow-up is 16 +/- 4 months now. So far, no clinical or lead complications with this access have been observed.

CONCLUSIONS

We have demonstrated that ICD lead placement through puncture of the right innominate vein is feasible. We propose the innominate vein as an alternative route for establishing venous access in patients requiring ICD revisions or upgrades who suffer from venous obstruction. ICD implanting physicians should acquaint themselves with the technique of right innominate vein puncture to use this vein as a bail-out strategy in patients with complicated venous access.

Tissue engineering of viable pulmonary arteries for surgical correction of congenital heart defects

BACKGROUND

Tissue-engineered pulmonary arteries could overcome the drawbacks of homografts or prosthetic conduits used in the repair of many congenital cardiac defects. However, the ideal scaffold material for tissue-engineered conduits is still subject of intensive debate. In this study, we evaluated an acellularized allogeneic matrix scaffold for pulmonary artery tissue engineering with and without in-vitro reseeding with autologous endothelial cells in the pulmonary circulation in a growing sheep model.

METHODS

Ovine pulmonary arteries (n = 10) were acellularized by trypsin/ethylenediamine tetraacetic acid incubation. Autologous endothelial cells were harvested from carotid arteries, and the pulmonary conduits were seeded with endothelial cells. We implanted in-vitro, autologous, reendothelialized (group A, n = 5) and acellularized pulmonary conduits (group B, n = 5) in the pulmonary circulation. The animals were sacrificed 6 months after the operation. Explanted valves were examined histologically and by immunohistochemistry.

RESULTS

The conduit diameter increased in both groups (group A, 44% +/- 11%; group B, 87% +/- 18%; p < 0.05). In group A, however, a proportional increase in diameter was present, whereas in group B, a disproportionate increase resulting in aneurysm formation was observed. Histologically, the conduit wall integrity was destroyed in group B and preserved in group A. In group B, the extracellularmatrix degenerated with a reduced amount of collagens and proteoglycanes. Furthermore, no elastic fibers were detectable. In contrast, the extracellularmatrix in group A was close to native ovine tissue.

CONCLUSIONS

Tissue-engineered pulmonary conduits (autologous endothelial cells and allogeneic matrix scaffolds) functioned well in the pulmonary circulation. They demonstrated an increase in diameter and an extracellular matrix comparable to that of native ovine tissue.

Aspekte der Mitralklappenrekonstruktion bei der chirurgischen Therapie der Mitralklappeninsuffizienz

Mitral valve repair (MVR) is the golden standard for the surgical treatment of mitral valve regurgitation and is superior to mitral valve replacement in terms of perioperative and long-term morbidity and mortality. However, the underlying disease has a significant impact on the functional long-term result of the repair. To evaluate the results of MVR, patients have to be divided by the underlying disease, degenerative mitral valve regurgitation, rheumatic mitral valve regurgitation, ischemic mitral valve regurgitation, and mitral valve regurgitation due to advanced cardiomyopathy. The best functional result for MVR can be achieved for degenerative mitral valve regurgitation (10-year freedom from reoperation for recurrent mitral regurgitation up to 94%) followed by patients with rheumatic mitral valve regurgitation (10-year freedom from reoperation for recurrent mitral regurgitation up to 82%). The progress in the underlying disease of the mitral valve is responsible for recurrent mitral valve regurgitation in these patients. For both underlying disease the 10-year survival rate is > 75%. For patients with ischemic mitral valve regurgitation the functional and survival rates are worse with a 5-year survival rate < 60% and recurrent mitral valve regurgitation > MI (mitral valve insufficiency) II degrees in 28% of patients within 6 months. However, ischemic mitral valve regurgitation is not a disease of the valve, it is a disease of the myocardium; thus, the myocardium is the key factor influencing the functional results of MVR and not pathologic changes in the mitral valve per se. There are no long-term results on patients operated on MI in conjunction with advanced cardiomyopathy; however, the initial mid-term results are encouraging with improved survival. Besides the underlying disease the timing of surgery is of utmost importance for the long-term survival; patients with preoperative NYHA functional class III/IV have a significantly worse short-term and long-term outcome compared to patients operated on for significant mitral valve regurgitation who have only minor or even no symptoms (NYHA class I/II). However, the compliance to undergo complex open-heart surgery via a median sternotomy in asymptomatic patients is very low. Minimally invasive endoscopic mitral valve repair may be an option to increase compliance in these patients, which will result in improved long-term survival with a normal life expectancy.

Effectiveness and safety of internal rectilinear biphasic versus monophasic defibrillation in patients undergoing cardiac surgery

BACKGROUND

Recently it has been shown that biphasic external shocks are more effective in the treatment of ventricular fibrillation (VF) compared with monophasic external shocks in terms of number of defibrillation attempts and maximal energy used for termination of VF. Biphasic defibrillators apply different biphasic impulse forms, depending on technology. To the authors' knowledge, there are no existing data concerning the effects of rectilinear biphasic internal shocks in patients undergoing cardiac surgery. The purpose of this study was to compare monophasic with rectilinear biphasic internal shock waveforms for termination of VF in patients undergoing cardiac surgery.

METHODS

One hundred thirty-four patients scheduled for elective cardiac surgery were prospectively randomized either to monophasic (group A) or biphasic (group B) internal defibrillation. Defibrillation was started with 7 J and increased stepwise to 30 J in each group until successful termination of VF after aortic declamping. The number of defibrillations, as well as the cumulative and maximal energy for termination of VF, were determined. Preoperatively, intraoperatively, and postoperatively troponin T, total creatine phosphokinase (CPK), and CPK- MB isoenzymes were measured.

RESULTS

In 64 patients (47%) VF occurred. The groups consisted of 32 patients each. The number of defibrillations (1.3 +/- 0.6 v 1.9+/- 1.2; p = 0.013), maximal energy per patient (7.9 +/- 2.5 v 11.6 +/- 7.32; p = 0.006), and cumulative energy (10.1 +/-6.1 v 21.3 +/- 24.1; p = 0.016) for successful termination of VF were significantly reduced in group B. Troponin T, CPK, and CPK-MB did not differ between groups.

CONCLUSIONS

Results of this study indicate that rectilinear biphasic internal defibrillation is more effective in the treatment of VF during cardiac surgery than is monophasic defibrillation. However, no significant difference in myocardial damage could be detected between groups.

Upregulation of endothelial adhesion molecules in hearts with congestive and ischemic cardiomyopathy: immunohistochemical evaluation of inflammatory endothelial cell activation

OBJECTIVE

In recent years many data emphasized, that inflammatory reactions seem to be involved in the pathogenesis of ischemic (ICM) and congestive (CCM) heart disease. Since, it is well known that endothelial adhesion molecules play a pivotal role in the initiation and maintenance of inflammatory reactions we therefore, evaluated the endothelial expression of a wide variety of different adhesion molecules in hearts suffering from ICM and CCM.

METHODS

Tissue samples from coronary arteries, and left and right ventricle myocardium originating form heart with ICM and CCM were evaluated. Tissue samples from healthy human donor hearts, which were not transplanted, served as controls. Evaluated adhesion molecule expression: selectin-family ELAM-1, CD62, immunoglobulin-supergene-family PECAM-1, ICAM-1, VCAM-1, integrin-family VLA-1,-2,-3,-4,-5, and -6, complementary-adhesion-molecules CD34, CD44 and the von-Willebrand-factor (vWF).

RESULTS

While endocardial surfaces and coronary arteries revealed only little differences when comparing tissue samples originating from healthy donor hearts and those suffering from ICM and CCM, significant differences were found within the myocardial microvasculature. Both kinds of diseased hearts showed stronger expressions for CD62, ELAM-1, ICAM-1 and VCAM-1 (only CCM) than controls. More and above, integrin molecules showed differential expressions too. Whereas, VLA-1 showed stronger expressions in diseased hearts, VLA-3,-5, and -6 were expressed much weaker in those hearts. Complementary adhesion molecules (CD34/CD44) did not show significant differences and the vWF was not found in any sample.

CONCLUSIONS

Inflammatory reactions play a pivotal role in the propagation and maintenance of both these cardiac detoriating diseases.

Evolving Strategies for Treatment of Acute Aortic Dissection Type A

OBJECTIVE

To assess the outcome of 3 different surgical approaches for treatment of acute aortic dissection type A (AADA).

METHODS AND RESULTS

Between October 1990 and October 2003, we operated on 295 patients (pts) for AADA. Follow-up was complete for 257 pts (87%). Supracommissural replacement (SCR) of the ascending aorta was applied to 145 pts, 64 pts received a composite replacement (comp), and 48 pts were treated with the aorta valve-sparing (AVS) reimplantation technique. Pts in SCR were older compared with AVS and comp (P=0.002), gender (overall 65% male, P=0.143) and presence of Marfan syndrome (overall 5%, P=0.109) were comparable. Cannulation of the aorta was performed more often in AVS (58%) than in comp (19%) or SCR (22%; P<0.001). Mean operation time, extracorporeal circulation time, and aortic cross-clamp time differ significantly between groups (P<0.001, respectively). Stay in the intensive care unit (P=0.12) and time of hospitalization (P=0.32) were comparable. Overall perioperative mortality was 24% and did not show significant differences between groups (AVS 10.4% versus comp 28% versus SCR 26%; P=0.053). Incidence of neurological complications was similar between groups (P=0.95). Mean time of follow-up was shorter for AVS (19+/-20 months) compared with comp (48+/-48 months) and SCR (46+/-45 months). Survival at 5 years was comparable with 89% for AVS, 85% for comp, and 80% for SCR (P=0.61). Two patients from AVS (4.1%) required reoperation for failure of the reconstructed valve. Pts in comp required less aortic reoperations than pts in SCR (comp 6.3% versus SCR 22%; P=0.005).

CONCLUSIONS

In acute aortic dissection type A, the reimplantation technique leads to results comparable to established techniques. Complete removal of diseased tissue, low incidence of reoperation, and lack of anticoagulation may favor this approach in selected patients.

Guided tissue regeneration: porcine matrix does not transmit PERV

OBJECTIVE

For cardiovascular tissue engineering, acellularized scaffolds of porcine matrices have been successfully used. However, the possibility of porcine endogenous retrovirus (PERV) transmission remains debatable. In this study, we investigated whether acellularized porcine vascular scaffolds cause cross-species transmission of PERV in a xenogenic model.

METHODS

Porcine pulmonary arteries were acellularized and implanted into sheep in orthotopic position (n=6). Cardiopulmonary bypass support was used for all operations. Blood samples were collected regularly up to 6 months after the operation, and cellular components were tested for PERV infection by PCR and RT-PCR. Grafts were explanted 6 and 12 months after implantation. Tissue samples were characterized by histology and electron microscopy and tested for PERV sequences.

RESULTS

All animals survived the procedure and follow up until explantation of the grafts. PERV DNA was detectable in acellularized scaffolds of porcine matrices. Acellular porcine pulmonary arteries scaffolds were repopulated in vivo by autologous cells of the host, leading to a vessel consisting of all cellular components of the vessel wall. No PERV sequences were detectable neither in all tested peripheral blood samples nor in tissue samples of in vivo recellularized grafts up to 6 months after implantation. Electron microscopy revealed no signs of graft infection by retrovirus.

CONCLUSIONS

Guided tissue regeneration of acellularized vascular porcine matrix scaffolds leads to structured vessels up to one year without risk of PERV transmisson.