Christian Sebening

External Stabilization of Long-Segment Tracheobronchomalacia Guided by Intraoperative Bronchoscopy

BACKGROUND Symptomatic obstruction of long-segment tracheal or bronchial portions either related to congenital instability or secondary to vascular compression are rare malformations, which remain difficult to manage. A method of external tracheal or bronchial stabilization is described. METHODS From July 1992 to April 1995, 7 children (age range, 4 months to 4 years; mean age, 19 months) and 1 adult (age, 46 years) were operated on for severe respiratory insufficiency. In 4 cases of congenital tracheal instability, 2 children had associated type IIIb esophageal atresia. Both children with esophageal atresia had previous operations (two and three times, respectively): 1 child had aortopexy and division of a patent ductus arteriosus and another child had distal tracheal resection elsewhere, both without relief of malacia. All children were intubated and ventilated since birth for 11 to 15 months. Secondary tracheobronchomalacia due to vascular compression was seen in 4 patients caused by double aortic arch (n = 2) and persisting ligamentum arteriosum after previous ligation of a patent ductus arteriosus (n = 2), with 1 child ventilated thereafter for 5 months. Operation was performed with the aid of extracorporeal circulation in all patients but 1, and consisted of transection of vascular rings and persistent ligamentum Botalli (n = 5), closure of multiple ventricular septal defects (n = 1) and extensive mobilization of the tracheobronchial tree as well as the great arteries. External stabilization of the severely dysplastic distal trachea (n = 6) or left main bronchus (n = 2) was achieved by suspending the malacic segment within an oversized and longitudinally opened ring-reinforced polytetrafluoroethylene prosthesis. Multiple plegeted sutures were placed extramucosally to the dysplastic tracheal wall and the dyskinetic pars membranacea, as well as to the polytetrafluoroethylene prosthesis in a radial orientation. Guided by simultaneous video-assisted bronchoscopy, reexpansion of the collapsed segments was achieved by gentle traction on the sutures while tying. RESULTS Stenosis-free tracheobronchial reexpansion was achieved in all patients, as seen on repeated bronchoscopies during hospitalization and thereafter. All patients were extubated within 1 to 12 days after the operation. There was one late death, unrelated to the procedure, in a 31-month-old child 20 months after the operation. All other patients are free of stridor and in excellent clinical condition 21 to 54 months (mean, 38 months) thereafter. CONCLUSIONS The presented method of bronchoscopically guided external tracheobronchial suspension within a ring-reinforced polytetrafluoroethylene prosthesis immediately relieves severe malacia of the trachea or main bronchi in infants as well as adults without necessitating resection. Midterm preliminary data suggest that growth potential of the affected segment exists within the oversized polytetrafluoroethylene prosthesis.

Modulation of coronary perfusion pressure can reverse cardiac dysfunction after brain death

BACKGROUND Brain death results in a rapid decline in left ventricular function, which has clinical relevance for organ transplantation. The aim of the present study was to investigate coronary perfusion changes during brain death and their role in cardiac dysfunction. METHODS In an in situ isolated canine heart model, brain death was induced by inflation of a subdural balloon catheter. The heart was perfused separately with the animals own blood by a pressure-controlled roller pump that was coupled to the measured aortic pressure. Myocardial contractility was estimated by the slope of the end-systolic pressure-volume relation. RESULTS Induction of brain death resulted in a transient hyperdynamic response, followed by a significant decrease in systemic vascular resistance, coronary blood flow, and the end-systolic pressure-volume relation (p<0.05). However, if coronary perfusion pressure was decoupled from aortic pressure and elevated to pre-brain death levels, coronary blood flow and the end-systolic pressure-volume relation were also restored to baseline levels. CONCLUSION Severe impairment of coronary blood flow may contribute to decreased contractility after brain death that can be reversed by modulation of coronary perfusion pressure.

Right ventricular function after brain death: Response to an increased afterload

OBJECTIVE A major cause of early postoperative morbidity and mortality after cardiac transplantation is right ventricular (RV) failure which is attributed to the inability of the donors RV to acutely compensate for the recipients elevated pulmonary vascular resistance. This study was performed to determine: (1) the acute effects of brain death on the RV function; and (2) the adaptation potential of the RV to a progressive increase in RV afterload. METHODS In 13 anesthetized, open-chest dogs (eight with brain death vs. five control with sham operation), brain death was induced by inflation of a subdural balloon catheter. Heart rate, RV systolic and end-diastolic pressure (RVSP, RVEDP), pulmonary arterial pressure (PAP), and cardiac output (CO), and pressure-length loops (sonomicrometry) were recorded. Afterload increase was induced 2 h after brain death induction by constriction of the pulmonary artery with an increase in RVP from 25 to 50 mmHg in 5 mmHg steps. RESULTS Cushing phenomenon occurred within a few minutes after brain death induction, with a significant increase of HR (229 +/- 10 vs. 89 +/- 6 min(-1), P < 0.001), CO (3.2 +/- 0.2 vs. 1.7 +/- 0.1 l/min, P < 0.001), PAP (30.4 +/- 2.5 vs. 15.5 +/- 1.3 mmHg, P < 0.01) RVSP (55 +/- 5 vs. 23 +/- 2 mmHg, P < 0.001) and RVEDP (7.4 +/- 0.9 vs. 3.3 +/- 0.6 mmHg, P < 0.001). All these values were also significantly (P < 0.01) higher than the time corresponding values of the control group. The analysis of the pressure-length loops showed a hypercontractile state. Within 15-60 min, all parameters turned to baseline and remained stable for up to 2 h. When afterload was increased progressively, RVEDP increased markedly in the brain death and slightly in the control group (9.4 +/- 0.7 vs. 4.2 +/- 1.1 mmHg, P < 0.01, at RVSP = 50 mmHg). On the other hand, the increase of peak positive dP/dt was significantly higher in the control group (430 +/- 37 vs. 644 +/- 55 mmHg/s, P < 0.01, at RVP = 50 mmHg). However, global RV pump function characterized by CO and stroke work was similar in both groups. While regional RV contractility remained unchanged in the brain death group in terms of pressure-length relationships, RV contractility significantly increased in the control group. CONCLUSION (1) Brain death per se does not result in an acute impairment of RV function. (2) While control animals adapt to an increased afterload by the homeometric, as well as the heterometric regulation, after brain death, an increase in RV preload follows elevations in RV afterload by the Frank-Starling mechanism subserving the increased stroke work required to ensure unchanged pump function.

Long-Term Outcome After External Tracheal Stabilization Due to Congenital Tracheal Instability

BACKGROUND Long-segment tracheobronchial malacia may cause life-threatening dysfunction of the airway system at different levels. This study presents the long-term follow-up (1992 through 2008) of patients who received surgical treatment with external tracheal stabilization in our institution. METHODS Eleven patients fulfilled the inclusion criteria. In surviving patients who presented for reexamination, pulmonary function testing, ergometry, and magnetic resonance imaging (MRI) were performed. RESULTS All patients could be weaned from the ventilator and discharged. Patients were aged a median 11 months (range, 3 to 48 months) at operation for tracheal compression. Age at follow-up was 9.1 years (range, 0.5 to 16.3 years). Median follow-up was 7.3 years (range, 0.1 to 15.1 years). Postoperatively, 1 patient was lost to follow-up, and 4 died at 2.6 years (range, 0.5 to 6.6 years) of comorbidities. Pulmonary function testing showed a moderate residual airflow restriction, with maximal vital capacity at 75% of normal (range, 45% to 92%). Treadmill exercise testing demonstrated 70% to 89% of the expected normal values for age. Magnetic resonance imaging examination confirmed tracheal patency, but the lumen of the left main bronchus in 2 patients was 50% smaller than on the right. Diaphragmatic motion was normal in all patients. CONCLUSIONS Children with congenital tracheal stenosis benefit from external tracheal stabilization. Survival in patients after external tracheal stabilization is significantly influenced by concomitant conditions.

Outcome After Mechanical Aortic Valve Replacement in Children and Young Adults

BACKGROUND We asked whether aortic valve replacement using a mechanical prosthesis would allow normalization of left ventricular function and structure in children and young adults. METHODS We performed a clinical follow-up examination in 30 patients with aortic valve replacement at 25 years of age or younger, including conventional and tissue Doppler echocardiography and magnetic resonance imaging. RESULTS Aortic valve replacement was performed at the median age of 14.3 years (range, 7.6 to 24.3 years) using a mechanical prosthesis (St. Jude Medical; median diameter, 23 mm; range, 17 to 27 mm). Indications were severe aortic stenosis in 6 of 30 patients, aortic regurgitation in 20 of 30 patients, or a combination of aortic stenosis and regurgitation (4 of 30 patients). Aortic valve replacement was a reoperation in 12 of 30 patients who primarily underwent aortic valvotomy at a median of 7.1 years (range, 1.0 to 11.3 years). In-hospital mortality was 0%. Follow-up was a median of 6 years (range, 1.2 to 14.5 years). Twenty-nine of 30 patients were in New York Heart Association functional class I without thromboembolic complications, cerebrovascular accidents, or major bleeding on oral anticoagulation. Left ventricular dilatation before aortic valve replacement was present in 20 of 30 patients but normalized in all but 4 patients on follow-up. Most patients showed a normal end-diastolic volume on magnetic resonance imaging, and 23 of 26 patients showed a normal left ventricular ejection fraction (median, 0.53; range, 0.33 to 0.75). Peak systolic strain of the left ventricular myocardium was a median of -13.3% (range, -0.5% to -31%), and was normal in 28 of 30 patients. CONCLUSIONS Aortic valve replacement in children and young adults offers a good treatment option and may lead to normalization of left ventricular size and function in most patients.

Modified Sliding Tracheal Plasty Using the Bridging Bronchus for Repair of Long-Segment Tracheal Stenosis

A child with severe respiratory distress, previously operated on at age 4 months for pulmonary sling and atrial septal defect, underwent reoperation at age 4 years because of long-segment congenital tracheal stenosis complicated by an abnormal branching of the trachea-bridging bronchus. We review the anatomy of that rare pathomorphology and describe a slide tracheoplasty that uses the bridging bronchus for treatment of this complex anomaly.

Replacement of valved right ventricular to pulmonary artery conduits: an observational study with focus on right ventricular geometry

ObjectiveTiming of the operation for exchange of right ventricular (RV) to pulmonary artery (PA) conduits is a matter of considerable debate. We aimed to study the course of right ventricular dimension in patients undergoing conduit exchange.Patients and methodsWe retrospectively studied all patients who underwent implantation and or replacement of RV/PA conduits during the time period between 1990 and 2005. Clinical and echocardiographic data were recorded as obtained at follow-up visits.ResultsA total of 229 (144 boys and 85 girls) underwent surgery for implantation and or replacement of RV/PA conduits during the study period. Patients were assigned to three age groups including 37 infants, 125 children aged 1−10 years and 67 patients more than 10 years of age. 185 pulmonary (81%) and 44 aortic homografts (19%) were implanted. Fifty-eight of these 185 patients (25%) required exchange of conduits after a median time of 6.4 (8 months–12 years) (median (range)). The follow-up was 7.55 (0.1–17) years. The survival of the patients after homograft change was 98%. Freedom from failure for aortic and pulmonary homografts at an interval of 10 years for all patients was 38.5% for aortic and 56.2% for pulmonary homografts (P = 0.018; Mann–Whitney). Age at conduit exchange (coefficient: −4.917; P < 0.001) and right ventricular end-diastolic dimension (RVDD) before conduit exchange (coefficient: 8.255; P < 0.001) were related to RVDD as measured by M-mode echocardiography at follow-up (“best subset” regression analysis; R squared = 0.746). RVDD decreased in 48/58 patients, remained unchanged in 8/58 and increased in 2/59 patients at follow-up. An increased RVDD was positively correlated to the duration of artificial ventilation after the operation for conduit exchange (R = 0.56; P < 0.001).ConclusionsReoperation for exchange of degenerated conduits should be performed early to prevent the development of irreversible structural myocardial changes and persistence of right ventricular dilatation.

Endothelial nitric oxide synthase gene polymorphism (Glu298Asp) and acute pulmonary hypertension post cardiopulmonary bypass in children with congenital cardiac diseases.

BACKGROUND Intra-cardiac repair of congenital cardiac diseases in children with left-right shunt is often associated with acute elevation of pulmonary artery pressure following cardiopulmonary bypass. We studied the correlation between the Glu298Asp polymorphism of the endothelial nitric oxide synthase gene and pulmonary hypertension in children with congenital cardiac diseases. METHODS AND RESULTS A total of 80 children with congenital cardiac diseases at a median age of 3.8 years, ranged 0.1-36.2 years, and 136 controls were enrolled. Most patients presented with significant left-to-right shunt - pulmonary-to-systemic blood flow of 2.8, with a range from 0.6 to 7.5. In all, 40 out of 80 children showed pulmonary hypertension with mean pressure of 42, ranged 26-82, millimetres of mercury. Thirty-one out of 40 children underwent intra-cardiac repair and 15 out of 31 operated patients were found to have an acute elevation of pulmonary artery pressure after cardiopulmonary bypass. The Glu298Asp polymorphism was identified using polymerase chain reaction and restriction fragment length polymorphism. Both in patients and in controls, the genotype distribution corresponded to the Hardy-Weinberg equilibrium. The gene frequency for Glu298Glu, Glu298Asp and Asp298Asp was not different in the control group compared to the patients (Armitage trend test: p = 0.37). The endothelial nitric oxide synthase polymorphism was related to acute post-operative elevation of pulmonary artery pressure (genotypic frequency 53.3 versus 25%; Armitage trend test: p = 0.038). In addition, the allelic frequency of the Glu298Asp was related to post-operative pulmonary hypertension (Fischers exact test: p = 0.048). The positive predictive value was 71.43%. CONCLUSION Patients with left-to-right shunt are more likely to develop acute elevation of pulmonary artery pressure after cardiopulmonary bypass when presenting with the Glu298Asp polymorphism of the gene endothelial nitric oxide synthase. This could be used as a genetic marker for the predisposition for the development of pulmonary hypertension after intra-cardiac repair.

The evolution of the pulmonary arterial sling syndrome, with particular reference to the need for reoperations because of untreated tracheal stenosis

BACKGROUND We present a group of infants and children with pulmonary arterial sling and tracheal stenosis. In some of the patients, the anomalously located pulmonary artery had previously been reimplanted, but without simultaneous repair of the trachea. METHODS From 1992 to 2007, we reimplanted the left pulmonary artery in 13 children with a pulmonary arterial sling. Their median age was 8 months, with a range from 1 to 72 months. We also performed tracheal resection with end-to-end anastomosis, or complex tracheal reconstructions. In 5 patients, the reoperation was indicated because of persistent tracheal stenosis not treated initially at first correction of the arterial sling. All patients presented with stridor and respiratory distress. Cardiac catheterization, bronchoscopy and multidetecting computer tomography angiography were performed in all cases prior to the operation. All operations were performed under cardiopulmonary bypass. RESULTS There was no operative or late mortality. The patients were extubated under bronchoscopic control. The mean period of intubation was 18 plus or minus 8 days, and the average follow-up was 8 plus or minus 4 years. The patients showed no signs of tracheal re-stenosis clinically or on bronchoscopy. The group of the patients under reoperations, however, required longer periods of intubation and hospitalization. CONCLUSION Our experience demonstrates that, in patients with a pulmonary arterial sling, any associated tracheal stenosis should be explored at the initial operation, since decompression of the trachea by reimplanting the anomalously located pulmonary artery fails to provide relief. The funnel trachea, if present, undergoes progressive stenosis, and will require surgical repair. The use of cardiopulmonary bypass permitted extensive mobilization of the tracheobronchial tree, and allowed us to perform a tension-free anastomotic reconstruction of the trachea.

Anomalous connection of the right superior caval vein to the morphologically left atrium.

Anomalous drainage of the right superior caval vein into the morphologically left atrium as an isolated cardiac malformation is a rare anomaly. Most patients present with cyanosis. Thus far, about 20 cases have been reported in the literature. We report a case of cyanosis due to this malformation in a male neonate, which was complicated by the meconium aspiration syndrome. The malformation was diagnosed by echocardiography and cardiac catheterization. Surgery resulted in complete recovery.