Background: Palliative surgery for the treatment of functionally univentricular heart malformations consists of a staged approach to separation of the pulmonary and systemic circulation, including the creation of a superior cavopulmonary connection. Literature on the superior cavopulmonary connection in porcine models lacks information on details of the procedure as well as data on its acute hemodynamic effects. In preliminary experiments, we were unable to reproduce an already published porcine model. Therefore, we used a conduit extension and cardiopulmonary bypass in order to achieve hemodynamic stability and still employ the commonly used straight downward pathway for the superior caval vein onto the right pulmonary artery, as in the human clinical setting. This model of a univentricular circulation utilising the superior cavopulmonary anastomosis is intended to be applied in the setting of unilateral diaphragmatic palsy. Hence, we aim to investigate the effect of unilateral diaphragmatic pacing in a reproducible model of univentricular physiology. Methods: Therefore, we constructed an anastomosis between the superior caval vein and the right pulmonary artery (RPA) in 14 pigs on cardiopulmonary bypass using a 12 mm expanded polytetrafluorethylene interposition graft. Six pigs received a bidirectional cavopulmonary connection with unrestricted atrial septal communication (BDCPC), while eight pigs received a unidirectional cavopulmonary connection (UDCPC) to the excluded RPA. Results: The BDCPC resulted in an impaired cardiopulmonary state (cardiac output dropped from 3.15 ± 0.21 to 2.17 ± 0.19 L/min; p < 0.01), mean arterial pressure plummeted (from 80.8 ± 3.7 to 49.3 ± 7.3 mmHg; p = 0.02), arterial lactate concentration rose (from 0.82 ± 0.09 to 4.36 ± 0.96 mmol/L; p = 0.01), arterial oxygen saturation dropped (from 95.8 ± 1.1 to 60.9 ± 10.4%; p < 0.01), and right ventricular function deteriorated (tricuspid annular plane systolic excursion decreased from 12 ± 0.7 to 5 ± 0.7 mm; p < 0.01). In contrast, in the UDCPC group, the cardiopulmonary parameters indicated a stable condition. Conclusions: Consequently, a UDCPC is a more suitable acute model in pigs for a univentricular circulation. The model’s reproducibility may aid in future research on partial cavopulmonary connection.

Unilateral diaphragmatic paralysis in children with univentricular circulation poses significant challenges, including impaired hemodynamics and increased postoperative complications. Restoring diaphragmatic function is crucial to mitigate these risks. This study investigates the feasibility of automated stimulation of the paretic diaphragm half using electromyography (EMG) signals from the non-paretic side following transection of the right phrenic nerve. Our findings demonstrate successful automated stimulation, suggesting the potential development of an EMG-triggered synchronized unilateral diaphragmatic pacemaker. This innovative approach holds promise as a novel therapeutic intervention for managing unilateral diaphragmatic paralysis in pediatric patients with univentricular circulation.

Abstract Background A frequent complication of Fontan operations is unilateral diaphragmatic paresis, which leads to hemodynamic deterioration of the Fontan circulation. A potential new therapeutic option is the unilateral diaphragmatic pacemaker. In this study, we investigated the most effective stimulation location for a potential fully implantable system in a porcine model. Methods Five pigs (20.8 ± 0.95 kg) underwent implantation of a customized cuff electrode placed around the right phrenic nerve. A bipolar myocardial pacing electrode was sutured adjacent to the motor point and peripherally at the costophrenic angle (peripheral diaphragmatic muscle). The electrodes were stimulated 30 times per minute with a pulse duration of 200 µs and a stimulation time of 300 ms. Current intensity was the only variable changed during the experiment. Results Effective stimulation occurred at 0.26 ± 0.024 mA at the phrenic nerve and 7 ± 1.22 mA at the motor point, a significant difference in amperage (p = 0.005). Even with a maximum stimulation of 10 mA at the peripheral diaphragm muscle, however, no effective stimulation was observed. Conclusion The phrenic nerve seems to be the best location for direct stimulation by a unilateral thoracic diaphragm pacemaker in terms of the required amperage level in a porcine model.

Abstract Background The porcine gall bladder and cystic duct gained attention in experimental research aimed at improving human clinical care. While the common bile duct has been investigated before, there is almost no data on the porcine cystic duct. Its relevance for research originates from its potential use in xenotransplantation. Methods We included 10 consecutive pigs (1♀, 9♂) that had been sacrificed after participation in another study. At necropsy, the distance from the biliary papilla to the gall bladder (gall bladder distance) was measured. The cystic duct was then subjected to linear traction. Ethical approval for the study was granted. Associations between force measurements and anatomical parameters were tested by correlation analysis. Results The pigs had a mean body weight of 21.9 kg (standard deviation 2 kg), a mean liver weight of 590 g (standard deviation 88 g), and a mean crown rump length of 67.3 cm (standard deviation 3 cm). The gall bladder distance was 8.2 cm (95% confidence interval: 7.6–8.7 cm). The cystic duct withstood mean linear traction forces of 4.8 N (95% confidence interval: 3.7–5.8 N) and could be elongated by a mean of 6 mm (95% confidence interval: 3.9–8 mm). Linear breaking strength was neither correlated to gall bladder distance (R = 0.3, 95% confidence interval: − 0.41 to 0.78, P = 0.406) or crown rump length (R = 0.42, 95% confidence interval: − 0.28 to 0.83, P = 0.222) nor liver weight (R = 0.02, 95% confidence interval: − 0.62 to 0.64, P = 0.954) or body weight (R = 0.36, 95% confidence interval: − 0.35 to 0.81, P = 0.304). This was also true for gall bladder distance. Conclusions Our study indicates that allometric parameters were not associated with the gall bladder distance or its resistance to traction forces. Consequently, substantial variation of these parameters can be expected in these surgically important parameters, which cannot be derived from easily accessible anatomical parameters.

Biomechanics are gaining ground in gastroenterology in the creation of educational models and to describe the necessary forces to perforate hallow organs during endoscopy. We thus investigated the breaking forces of porcine intestinal segments and whether they could be predicted based on body weight or crown–rump length. Based on a priori power-analyses, 10 pigs were included. The breaking forces were determined with a motorized test stand. We found that the breaking forces of intestinal segments were different (H(6) = 33.7, p < 0.0001): Ileal breaking force (x¯ = 24.14 N) was higher than jejunal (x¯ = 14.24 N, p = 0.0082) and colonic (x¯ = 11.33 N, p < 0.0001) breaking force. The latter was also smaller than cecal breaking force (x¯ = 24.6 N, p = 0.0044). Likewise, rectal (x¯ = 23.57 N) breaking force was higher than jejunal (p = 0.0455) and colonic (p = 0.0006) breaking force. Breaking forces were not correlated to body weight or crown–rump length (R < 0.49, p > 0.148). Intestinal segments differ in their breaking forces. The colon had the least resistance to traction forces. It remains to be determined if similar relationships exist in humans in order to validate porcine models for endoscopy and surgery.

Unilateral phrenic nerve damage is a dreaded complication in congenital heart surgery. It has deleterious effects in neonates and children with uni-ventricular circulation. Diaphragmatic palsy, caused by phrenic nerve damage, impairs respiratory function, especially in new-borns, because their respiration depends on diaphragmatic contractions. Furthermore, Fontan patients with passive pulmonary perfusion are seriously affected by phrenic nerve injury, because diaphragmatic contraction augments pulmonary blood flow. Diaphragmatic plication is currently employed to ameliorate the negative effects of diaphragmatic palsy on pulmonary perfusion and respiratory mechanics. This procedure attenuates pulmonary compression by the abdominal contents. However, there is no contraction of the plicated diaphragm and consequently no contribution to the pulmonary blood flow. Hence, we developed a porcine model of unilateral diaphragmatic palsy in order to evaluate a diaphragmatic pacemaker. Our illustrated step-by-step description of the model generation enables others to replicate and use our model for future studies. Thereby, it might contribute to investigation and advancement of potential improvements for these patients.

Unilateral diaphragmatic paralysis in patients with univentricular heart is a known complication after pediatric cardiac surgery. Because diaphragmatic excursion has a significant influence on perfusion of the pulmonary arteries and hemodynamics in these patients, unilateral loss of function leads to multiple complications. The current treatment of choice, diaphragmatic plication, does not lead to a full return of function. A unilateral diaphragmatic pacemaker has shown potential as a new treatment option. In this study, we investigated an accelerometer as a trigger for a unilateral diaphragm pacemaker (closed-loop system).Seven pigs (mean weight 20.7 ± 2.25 kg) each were implanted with a customized accelerometer on the right diaphragmatic dome. Accelerometer recordings (mV) of the diaphragmatic excursion of the right diaphragm were compared with findings using established methods (fluoroscopy [mm]; ultrasound, M-mode [cm]). For detection of the amplitude of diaphragmatic excursions, the diaphragm was stimulated with increasing amperage by a cuff electrode implanted around the right phrenic nerve.Results with the different techniques for measuring diaphragmatic excursions showed correlations between accelerometer and fluoroscopy values (correlation coefficient 0.800, P < 0.001), accelerometer and ultrasound values (0.883, P < 0.001), and fluoroscopy and ultrasound values (0.816, P < 0.001).The accelerometer is a valid method for detecting diaphragmatic excursion and can be used as a trigger for a unilateral diaphragmatic pacemaker.

BACKGROUND:This study's objective was to determine the effect of age, prolonged bypass, and hypothermia on serum cefazolin concentrations in children undergoing cardiac surgery. METHODS:A prospective, single-center, observational study was conducted, examining children undergoing cardiac surgery. Participants received cefazolin intravenously approximately 1 hour before skin incision, 3 hourly intraoperatively, and 8 hourly postoperatively. Blood samples were collected at 6 to 8 time points intraoperatively and at 6 time points in the first 24 hours postoperatively. Target unbound serum cefazolin concentrations were 2 mg/L. RESULTS:Sixty-eight patients were enrolled in the study, and 64 were included in the analysis. All maintained concentrations ≥ 2 mg/L throughout the operation. Nineteen patients (30%) did not maintain concentrations ≥ 2 mg/L in the first 24 hours after surgery. Older, larger children (P < .0001) were significantly less likely to achieve target unbound serum cefazolin concentrations. CONCLUSIONS:Intraoperative cefazolin concentrations reached the target concentration in all pediatric cardiac surgical cases. Postoperative cefazolin dosing appears to be insufficient to achieve minimum inhibitory concentrations in many patients.

Objectives: Bilateral pulmonary artery banding (PAB) is an initial palliation option in the management of single ventricle patients including hypoplastic left heart syndrome (HLHS). PAB yields good results especially in high-risk HLHS patients. However, there is concern with pulmonary artery growth after PAB. In addition, it has been speculated that longer duration of PAB might have a more pronounced negative effect on PA size.

Background. To characterize treatment of transposition of great arteries with ventricular septal defect and left ventricular outflow tract obstruction (LVOTO) in Germany and to analyze late outcomes. Methods. German Registry for Congenital Heart Defects data were searched for transposition of great arteries with ventricular septal defect and LVOTO. One hundred thirty-nine patients were treated at 15 institutions between 1968 and 2016. Risk factor analyses were performed for the primary endpoints of death and reoperation/reintervention. Results. Follow-up was 88% complete, with a mean follow-up of 16 +/- 7 years (median, 15 years [range, 1-48]) and a cumulative follow-up comprising 1739 patient-years. Atrial switches were performed in 15%, Rastelli procedure in 48%, Nikaidoh procedure in 9%, reparation a l'e tage ventriculair (REV) in 8%, and arterial switch in 20%. Actuarial survival at 30 years was 86% (range, 83%-90%), with no difference between repairs. Freedom from primary reoperation was 17%(range, 12%-21%) at 30 years. Freedom from reoperation for LVOTO at 30 years was 74% (range, 70%-78%). Recurrent LVOTO was found in 9%, with risk factor diffuse subvalvular LVOTO(odds ratio, 9.8; P = .04). Late freedom from first reoperations other than right ventricle-to-pulmonary artery conduit was 60% (range, 59%-61%), with predictors multiple ventricular septal defect (hazard ratio, 6; P = .03) and Rastelli procedure (hazard ratio, 12; P = .03). Absolute reoperation rates were lowest for REV procedure (16% at a mean of 12 years). Conclusions. Long-term survival is good without detectable differences between operations. Since the early 2000s increasing use of Nikaidoh and REV procedures was obvious, with REV performing particularly well. Surgery-specific and -unspecific reoperations are most common after the Rastelli technique. (C) 2020 by The Society of Thoracic Surgeons

Objective: The increasing experience in repair and follow up of tetralogy of Fallot(TOF), reported in many publications, have shown that transannular patch repair (TAP) resulting in pulmonary regurgitation(PR), might lead to right ventricular dilation and concomitant deleterious effects, e.g., right and also left ventricular dysfunction, with the need for repeated reinterventions. This is also confirmed by our own experience, which comprises of 502 TOF repairs from 1995 to 2005 (n = 216, TP1) and from 2005 to 2016 (n = 286, TP2). Over the years the percentage of TAP repair decreased from 68.5% in TP1 to 55.2% in TP2 (freedom from reoperation 79.7% ± 2.9 in TP1 vs. 84.5% ± 7.1 in TP2). This was due to continuous refinement of RVOT repair techniques aiming at limiting the rate of TAP. Most recently, to lower the amount of TAP repairs even more, we added since Nov 2016 to our armamentarium the delamination technique (DL), published recently by the group of Padua.

OBJECTIVES:Because data for neonates are limited, optimal management of critical aortic stenosis remains controversial (balloon valvotomy [BV] or open valvoplasty [OV]). In a center with balanced experience in both methods, we hypothesized that OV can provide a better individualized approach than blunt BV and better serve long-term outcomes. METHODS:A retrospective review of data and follow-up (survival, freedom from operation/replacement) of all neonates, suitable for biventricular repair, undergoing aortic valve procedure (1989-2015), was performed. RESULTS:One hundred three patients were concomitantly treated (BV [n = 51], OV [n = 52). Median age was 8 days, median aortic annulus Z-score was -1.3 for BV (range, -3.9 to 2.0) and OV (-3.9 to 3.2) groups. Operative mortality after BV or OV was 8% (n = 4) and 4% (n = 2), respectively. With a 13-year median follow-up, 10-year freedom from operation was 36% and 66% after BV or OV, respectively. Valve replacement was ultimately required in 32 patients (n = 20 [39%] in the BV group; n = 12 [23%] in the OV group) within a 5.9-year median time. After OV, tricuspid arrangement of the repaired aortic valve provided a 10-year freedom from operation and replacement of 87% and 95%, respectively. In multivariate analysis, associated left heart malformations, BV, nontricuspid geometry, and inadequate post procedural result were predictive of operation and replacement. CONCLUSIONS:In neonates with critical aortic stenosis, both methods (BV and OV) offer excellent survival benefit. OV significantly minimizes the need for operation, whereas BV did not postpone age of replacement. Clearly superior results are achieved with OV when a post repair tricuspid arrangement is obtained.

Objective and methodsThe use of conventional metal stents in infants is severely limited by subsequent somatic growth. The use of a breakable balloon expandable stent (BS) designed for initial implant at small diameters but with properties that allow unlimited dilation in line with growth has potential advantages in this patient group. This study reports our experience with this stent between 2010 and 2014. A total of 17 BS were implanted in 14 infants (mean age 4.8 months). All but one stent was placed into the aorta to treat coarctation. ResultsAll implantations were successful and initial gradients dropped from a mean of 25-6 mm Hg (range from 1-50 down to 0-24 mm Hg). Mean follow-up was 3.3 years (range 5 days to 7 years) with a total cumulative follow-up of 46.7 patient years. Stent redilation was performed a median of 2.5 times (range 0-5). Sixteen stents in 13 patients remain in place. Following redilation beyond 10 mm, circumferential integrity of the BS was lost in 10 patients. No further stent implantation or related surgery was necessary. A 3 mm dissection occurred in one patient after redilation. ConclusionsThe BS performed well in terms of relief of stenosis and could be successfully dilated during the phase of the infants' most rapid growth. Mild intimal proliferation occurred in some patients early after implantation. In the course of the stepwise redilations and growth adjustments, both, planned longitudinal and transverse fractures occurred without allowing a collapse of the stented area.

Objectives: Any aortic valve (AoV) operation in children (repair, Ross or mechanical replacement) is a palliation and reinterventions are frequent. AoV repair is a temporary solution primarily aimed at allowing the patient to grow to an age when more definitive solutions are available. We assessed AoV repair effectiveness across the whole age spectrum of children, excluding AoV disease secondary to congenital heart disease. Established program began in 1989 for neonates and 2003 for older children.

Objectives: Studies in adults have shown that women have higher rates of both major adverse cardiac events and mortality from myocardial infarction compared with men. Very limited data are available if gender affects the outcome of patients after Norwood operation in large single-center series. Our objective was to determine if female sex (F) is associated with increased mortality after Norwood compared with male (M) patients.

BACKGROUND:Gastrointestinal blood flow may be compromised during and after vasopressor support. Endothelin expression may lead to microcirculatory dysfunction. The aim of this study was to analyze the effect of vasopressin and dobutamine after mesenteric ischemia on the gastrointestinal mucosal microcirculation, endothelin expression, and morphologic injury. MATERIALS AND METHODS:Pigs were studied in four groups (six pigs in each group): 1, sham; 2-4 ischemia (1 h superior mesenteric artery occlusion with 30 min reperfusion and 30 min of vehicle [2], dobutamine [3], or vasopressin [4] administration, followed by 30-min break and thiopental-induced hypotension [3, 4]). Blood flow of the gastric, jejunal, and rectosigmoidal mucosa was measured. At the end of the experiment, the mucosal expression of endothelin-1 (ET-1) and its receptor subtypes A (ETA) and B were determined by polymerase chain reaction. Mucosal injury, apoptotic cell death, and leukocytic infiltration were determined by histology and immunohistochemical analysis of cleaved caspase-3 and myeloperoxidase. RESULTS:Mesenteric ischemia increased jejunal mucosal ET-1 gene expression, arterial ET-1, intestinal fatty acid binding protein, and jejunal mucosal injury compared with sham. Dobutamine increased arteriovenous shunting at the cost of the jejunal mucosal blood perfusion. This was associated with an increased expression of ET-1 and ETA and mucosal leukocytic infiltration. In contrast, vasopressin increased postischemic capillary density and tissue blood flow. This was associated with a lower ET-1 gene expression. Vasopressin did not induce jejunal mucosal leukocytic infiltration. CONCLUSIONS:Vasopressin reduces mesenteric ischemia-associated alterations of the microcirculation and tissue integrity, whereas dobutamine does not.

Objectives: Aortic arch reconstruction during the Norwood operation almost always requires patch material. Reasons for arch reobstruction are still a matter of international debate. So far, pulmonary allografts demonstrated superior results in Norwood type reconstructions compared with other patch material. Unfortunately, the shortage of allografts represents a major challenge. Therefore, a suitable alternative is sought for. So, we studied in a retrospective analysis the incidence of aortic arch reobstruction in patients with Norwood type operations using pulmonary allografts compared with ADAPT treated bovine pericardium (CardioCel Admedus).