Tsvetomir Loukanov

Management of Adult Patients with Perioperative Pulmonary Hypertension: Technical Aspects and Therapeutic Options

Pulmonary hypertension (PH) is an independent risk factor for increased mortality in patients undergoing heart surgery. Existing chronic PH may be exacerbated by acute post-bypass PH, and this can lead to acute right ventricular failure. The prevention and treatment of right ventricular failure in cardiac surgery is based on three principles: optimize right ventricular preload, improve right ventricular contractility, minimize right ventricular afterload. The last of these may involve specific measures such as the inhalation of nitric oxide (NO) or of the stable prostacyclin analogue iloprost. The advantage of these inhalable substances is their pulmonary selectivity, and the subsequent reduction in systemic side effects. In order to avoid disastrous results in high-risk cardiac surgical patients, intra- and post-operative monitoring with pressure lines, a qualified team that pays attention to details, and an aggressive and early treatment in the operating room with inhaled iloprost and/or NO is necessary. The philosophy of ‘wait and see’ should be abandoned in favour of ‘be suspicious and act early’. In a prospective randomized trial, the efficacies of inhaled iloprost and of inhaled NO in the therapy of PH immediately following weaning from cardiopulmonary bypass in cardiac surgical patients were compared. Iloprost proved to be significantly more effective with respect to mean pulmonary arterial pressure, pulmonary vascular resistance, and cardiac output than inhaled NO.

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.

Hypoplastic left heart syndrome - unresolved issues.

Hypoplastic left heart syndrome (HLHS) is one of the most challenging congenital heart defects. At present, it is expected that – at best – 70% of newborns with HLHS will reach adulthood. This review addresses the problems of right ventricular (RV) failure and insufficient growth of pulmonary vasculature in these patients. In order to further improve long-term prognosis translational research to control RV function, growth of pulmonary arteries and progress in chronic circulatory support are clearly needed to provide a further improvement for adults with HLHS.

Right Ventricular Failure and Pathobiology in Patients with Congenital Heart Disease – Implications for Long-Term Follow-Up

Right ventricular dysfunction represents a common problem in patients with congenital heart defects, such as Tetralogy of Fallot or pulmonary arterial hypertension. Patients with congenital heart defects may present with a pressure or volume overloaded right ventricle (RV) in a bi-ventricular heart or in a single ventricular circulation in which the RV serves as systemic ventricle. Both subsets of patients are at risk of developing right ventricular failure. Obtaining functional and morphological imaging data of the right heart is technically more difficult than imaging of the left ventricle. In contrast to findings on mechanisms of left ventricular dysfunction, very little is known about the pathophysiologic alterations of the right heart. The two main causes of right ventricular dysfunction are pressure and/or volume overload of the RV. Until now, there are no appropriate models available analyzing the effects of pressure and/or volume overload on the RV. This review intends to summarize clinical aspects mainly focusing on the current research in this field. In future, there will be increasing attention to individual care of patients with right heart diseases. Hence, further investigations are essential for understanding the right ventricular pathobiology.

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.

Patent ductus arteriosus in preterm infants: Benefits of early surgical closure

Background Patent ductus arteriosus in preterm neonates leads to significant morbidity. Surgery is indicated when pharmacological treatment fails or is contraindicated, but the optimal timing remains unclear. Methods We retrospectively studied all 41 preterm neonates with symptomatic ductus arteriosus who underwent ligation between 1988 and 2009. We compared early complications rates and late neurological outcomes of patients operated on before 21 days of age with these operated on later. Results The median gestational age at birth was 26 weeks (range 23–31 weeks) and median weight at birth was 930 g (range 510–1500 g); 34 (82.9%) received pharmacological treatment before surgery. Fourteen (34.1%) patients underwent surgical closure before 21 days of age and 27 (65.9%) after 21 days. The 2 groups did not differ significantly in gestational age and weight at birth, but those operated on after 21 days received significantly more pharmacological treatment cycles. Patients in the early closure group had shorter intubation times: median 23 days (range 13–35 days) vs. 43 days (range 27–84 days; p < 0.001) and shorter neonatal intensive care unit stay: median 44 days (range 31–66 days) vs. 76 days (range 41–97 days; p < 0.001), with significantly lower rates of bronchopulmonary dysplasia, intraventricular hemorrhage, and acute renal failure, and significantly better neurological outcomes. Discussion Performing early ligation of symptomatic ductus arteriosus after unsuccessful pharmacological therapy in preterm neonates might lower complication rates and improve neurological outcome. Prospective randomized studies are needed to determine the optimal treatment.