Left Pulmonary Artery Obstruction Research Articles

Left Pulmonary Artery Occlusion Following Device Closure of Patent Ductus Arteriosus in Premature Infants

BackgroundDevice closure of a patent ductus arteriosus (PDA) is rapidly evolving, with the Amplatzer Piccolo Occluder (Abbott) receiving US Food and Drug Administration approval and becoming the first device approved for PDA closure in patients ≥700 g. We report on the first known cases of complete left pulmonary artery (LPA) occlusion following Piccolo closure of a PDA in premature infants. MethodsRetrospective chart analysis of PDA closures. ResultsWe have performed over 50 cases of Piccolo device closure of the PDA in preterm neonates in the past 2 years, with these 2 cases representing our only complications (4%). This represents a total complication rate similar to or lower than most centers that have published data for this procedure. ConclusionsAlthough rare, severe LPA obstruction can be seen in premature infants following device closure of the PDA. The Piccolo device is designed to ideally remain entirely intraductal. Although our device selection appeared to provide a device short enough for the given ductal length, we recommend, whenever possible, giving consideration to using the shortest possible device. We also recommend increasing the frequency of echocardiographic surveillance to weekly studies if at any time the imaging demonstrates an increase in the degree of obstruction/turbulence.

Aneurysms of the fetal arterial duct are usually benign.

Fetal arterial duct aneurysm, saccular, or fusiform enlargement of the arterial duct affect > 8% of pregnancies. It is uncommonly associated with serious sequelae postnatally, including thromboembolic events such as stroke and left pulmonary artery obstruction, rupture with demise, and vocal cord compression. Risk factors include maternal diabetes, late maternal age, maternal blood type A, large size for gestational age, and connective tissue disorders. The clinical importance remains unknown, making it difficult to determine how to monitor this finding postnatally. This is a retrospective echocardiogram study assessing the outcomes of fetally diagnosed arterial duct aneurysm. Images and records were reviewed to confirm the diagnosis and assess risk factors and outcomes. Descriptive statistics were performed. Fifty-three affected fetuses were identified. The median gestational age at diagnosis was 34.9 weeks (IQR 32.6, 36.6). The median maternal age was 31 years (IQR 27.3-34.1). Eight (15%) had maternal diabetes. The most common blood type was type O. The median maximal dimension of the aneurysm was 7.6 mm (IQR 6.1, 8.7). The aortic end was the maximal dimension in 67.9%. Median postnatal follow-up period was 76 days (IQR 7.5, 368). No patients sustained postnatal demise related to the duct, rupture of the ductal aneurysm, cerebral infarction, or other sequelae. No newborn had associated connective tissue disorders. No patients underwent ductal intervention. In our experience, no adverse outcomes related to the ductal aneurysm were identified. This should be considered when counselling families about the need for postnatal follow-up.

DECISION MAKING FOR DEVICE CLOSURE IN ADULTS WITH ‘HYPERTENSIVE PDA’–NON-INVASIVE CRITERIA: IMMEDIATE RESULTS

Objective: To find the mean pulmonary artery pressures (PAP) in adults (>12 years) Patent Ductus Arteriosus (PDA) with ‘reversible pulmonary hypertension’ after the device closure. Residual PDA and immediate complications (embolization, pulse loss, obstruction in the aorta or pulmonary artery) are to be reported.
 Study Design: Retrospective study.
 Place and Duration of Study: Tertiary Care Referral Hospital, from Aug 2007 to Jun 2020.
 Methodology: This retrospective study is descriptive. Data collected by convenience sampling from 3 tertiary care referral hospital. 981 patients were undergone PDA device closure during the period from Aug 2007 to June 2020. After informed consent, an initial assessment was done by history, clinical examination, x-ray chest PA view, electrocardiography (ECG), and transthoracic echocardiography (TTE). Reversible pulmonary hypertension was labeled based on non-invasive criteria including room air saturation >93% and cardiomegaly on x-ray chest. Patients who had <93% and normal heart size on x-ray chest were excluded. The lower limit for age was 12 years.
 Results: Nine Hundred Eighty One patients had undergone PDA device closure. 32 (n=32/981 3.3%) had fulfilled our inclusion criteria. The mean age was 22 ± 9 (13–45) years. Mean weight was 41 ± 11 (25-66) kg. Successful device closure was done in 30 patients (93.7%). Mean diameter of PDA was 7 ± 0.1 (4.5-13 mm. Mean PAP decreased from 59 ± 13 mmHg to 38 ± 19 mmHg (p<0.05). Commonest device used was Shasma duct occluder (n=16/32 50%) followed by Occlutech Duct Occluder (n=7/32 21.9%), while 2 had muscular VSD device (n=5/32 15.6%). In 2 patients, there was an underestimation of the size of PDA so the device was retrieved and replaced with another larger one successfully. Two patients had the device fully dropped into the main pulmonary artery before it was released. Larger size device was not available at that time so the patients were referred for surgery. None of our patients had device embolization or residual shunt on echo performed next day to the procedure. Neither any patient had residual pulmonary hypertension on echocardiography. There was no significant obstruction in the aorta in any patients. Two patients had mild left pulmonary artery obstruction. There was no significant obstruction in the aorta in any of our patients. There was pulse loss in 3 patients which were treated successfully with heparin infusion with no residual damage.
 Conclusion: Device closure is a feasible option in adults with hypertensive PDA while the decision of reversibility is based on non-invasive criteria.

Device deformation and left pulmonary artery obstruction after transcatheter patent ductus arteriosus closure in preterm infants

BackgroundTranscatheter closure of patent ductus arteriosus (PDA) is an effective alternative to surgical ligation in preterm infants. However, data on device deformation and risk of left pulmonary artery (LPA) obstruction remain scant. This study describes the outcomes and complications of transcatheter closure of PDA in preterm infants weighing <2500 g. MethodsAmplatzer Piccolo Occluder and Amplatzer Vascular Plug were used. Echocardiography was repeated at prespecified intervals. The device waist and length were assessed through lateral fluoroscopy immediately and at least 3 months after deployment. ResultsFourteen infants were prospectively enrolled (mean procedural weight 1335 g, procedural age 24 days), and all procedures were successful. There was no obstruction of adjacent vessels immediately after deployment. At follow-up, three infants developed aortic coarctation, all of which resolved gradually. Obstruction of the LPA occurred in eight infants, with five being severe cases. Compared with the shape immediately after deployment, the devices became significantly more flattened and lengthened at follow-up in patients with LPA obstruction. This deformation was nonsignificant in infants without any LPA obstruction. The ratio of the device waist after deployment to the nominal waist (<0.75) was highly predictive of LPA obstruction and late device deformation. The cannulated femoral vein was patent compared with the contralateral side. ConclusionsDevice deformation occurring late at follow-up is common and may be associated with LPA obstruction in preterm infants after transcatheter PDA closure. Meticulous device selection and implantation technique are crucial for minimizing the associated risks.

Follow-up after Percutaneous Patent Ductus Arteriosus Occlusion in Lower Weight Infants

To describe longer term outcomes for infants <6kg undergoing percutaneous occlusion of the patent ductus arteriosus (PDA). This was a retrospective cohort study of infants <6kg who underwent isolated percutaneous closure of the PDA at a single, tertiary center (2003-2017). Cardiopulmonary outcomes and device-related complications (eg, left pulmonary artery obstruction) were examined for differences across weight thresholds (very low weight, <3kg; low weight, 3-<6kg). We assessed composite measures of respiratory status during and beyond the initial hospitalization using linear mixed effects models. In this cohort of lower weight infants, 92 of 106 percutaneous occlusion procedures were successful. Median age and weight at procedure were 3.0months (range, 0.5-11.1months) and 3.7kg (range, 1.4-5.9kg), respectively. Among infants with pulmonary artery obstruction on initial postprocedural echocardiograms (n=20 [22%]), obstruction persisted through hospital discharge in 3 infants. No measured variables were associated with device-related complications. Rates of oxygenation failure (28% vs 8%; P<.01) and decreased left ventricular systolic function (29% vs 5%; P<.01) were higher among very low weight than low weight infants. Pulmonary scores decreased (indicating improved respiratory status) following percutaneous PDA closure. Percutaneous PDA occlusion among lower weight infants is associated with potential longer term improvements in respiratory health. Risks of device-related complications and adverse cardiopulmonary outcomes, particularly among very low weight infants, underscore the need for continued device modification. Before widespread use, clinical trials comparing percutaneous occlusion vs alternative treatments are needed.

Transcatheter closure of patent ductus arteriosus in children weighing 5 kg or less: Initial experienc

Introduction: Trans-catheter closure (TCC) of patent ductus arteriosus (PDAs) is a well-establishednon-surgical method of closure. Objectives: To evaluate safety, feasibility &amp; complicationsof device closure of patent ductus arteriosus (PDA) in small children weighing ≤ 5 kg with different types of devices for closure. Methods: patients with PDA underwent transcatheter closure, among whom 16 (33%) weighed 5 kg or less. All of these patients underwent transcatheter closure of PDA using an Amplatzer duct occluder I, Amplatzer duct occluder II or Amplatzer duct occluder 2 IIAS (Additional size) devices. Results: Sixteen patients (9 females &amp; 7 males) between theages 20 days to 16 months had undergone device closures. Amplatzer Duct Occluder (ADOI) was used in 12 cases, 3 were closed with Amplatzer Duct Occluder (ADO2) and one the smallest of all (1.6 kg) patientwere selected for closure with Amplatzer Duct Occluder (ADO2 AS).At 1 month after the closure, the signs and symptoms improved markedly in all patients, and PDAs were completely closed and devices remained in situ on follow-up. Mild obstruction of left pulmonary artery (n=2) and aortic isthmus flow (n=1) was noted at the time of discharge which gradually improved on follow up. Conclusions: TCC of PDAin small babies 5 kg or less is feasible &amp; safe alternative to surgical PDA closure in carefully selected patients. The immediate &amp; short-term outcomes have proven this method to be safe &amp; valid.

PATENT DUCTUS ARTERIOSUS DEVICE OCCLUSION

Objectives: To determine immediate outcomes and complication rate oftranscatheter closure of patent ductus arteriosus. Study Design: Retrospective analysis.Setting: CPE Institute of cardiology. Period: 2009 to May 2016. Materials and Methods:Two hundred and seventy four (274) results of transcatheter occlusion of PDA performed bypediatric cardiologists. All patients who underwent PDA occlusion regardless of their weighteither by ADO device or SHSMA occlude were included for analysis. SPSS V23 was used fordata processing. Frequency was calculated for qualitative variables and mean for quantitativeones. Results: The mean age of study participants was 9.57+8.82 years. There was femalepredominance with 65.7% females and 34.3% males. Regarding severity of PDA, 90 (32.8%)patients were presented with large PDA, 70 (25.5%) with moderately large PDA, 107 (39.1%)with moderate PDA and only 6 (2.2%) were presented with small sized PDA. Classical conicalshaped PDA was most common manifestation, diagnosed in 66.8% patients and long ampullashaped in 70 (25.5%) patients. Regarding complications, device embolization occurred in onepatient. Residual PDA in catheterization lab was present in 4 (1.5%) patients. Radial pulse lossoccurred in 6 (2.2%) patients for which heparin infusion was started until the pulse becamepalpable. Blood transfusion was required in 3 (1.1%) patients due to excessive blood lossduring the procedure. Mild left pulmonary artery obstruction due to protrusion of pulmonaryend of device occurred in 2 (0.7%) patients. Device protrusion into aorta was noted in only 16(5.8%), in all of these patients there was no aortic flow obstruction. Overall success rate was99.63%. There was no procedure related mortality. Conclusion: Percutaneous patent ductusarteriosus closure is safe with minimum number of complications. Pulse loss, protrusion o aorticend of device into aorta and residual PDA in cath lab (resolved within 24 hours) are commonprocedural complications.

IMMEDIATE RESULTS AND COMPLICATIONS

Objectives: To determine immediate outcomes and complication rate oftranscatheter closure of patent ductus arteriosus. Study Design: Retrospective analysis.Setting: CPE Institute of cardiology. Period: 2009 to May 2016. Materials and Methods:Two hundred and seventy four (274) results of transcatheter occlusion of PDA performed bypediatric cardiologists. All patients who underwent PDA occlusion regardless of their weighteither by ADO device or SHSMA occlude were included for analysis. SPSS V23 was used fordata processing. Frequency was calculated for qualitative variables and mean for quantitativeones. Results: The mean age of study participants was 9.57+8.82 years. There was femalepredominance with 65.7% females and 34.3% males. Regarding severity of PDA, 90 (32.8%)patients were presented with large PDA, 70 (25.5%) with moderately large PDA, 107 (39.1%)with moderate PDA and only 6 (2.2%) were presented with small sized PDA. Classical conicalshaped PDA was most common manifestation, diagnosed in 66.8% patients and long ampullashaped in 70 (25.5%) patients. Regarding complications, device embolization occurred in onepatient. Residual PDA in catheterization lab was present in 4 (1.5%) patients. Radial pulse lossoccurred in 6 (2.2%) patients for which heparin infusion was started until the pulse becamepalpable. Blood transfusion was required in 3 (1.1%) patients due to excessive blood lossduring the procedure. Mild left pulmonary artery obstruction due to protrusion of pulmonaryend of device occurred in 2 (0.7%) patients. Device protrusion into aorta was noted in only 16(5.8%), in all of these patients there was no aortic flow obstruction. Overall success rate was99.63%. There was no procedure related mortality. Conclusion: Percutaneous patent ductusarteriosus closure is safe with minimum number of complications. Pulse loss, protrusion o aorticend of device into aorta and residual PDA in cath lab (resolved within 24 hours) are commonprocedural complications.

Transcatheter occlusion of the patent ductus arteriosus in premature infants weighing less than 1200 g

ObjectivesOver the last few decades different strategies have been proposed to treat persistent ductal patency in premature infants. The advent of the Amplatzer Duct Occluder II Additional Size (ADOIIAS) provided...

Stent angioplasty to relieve left pulmonary artery obstruction caused by patent ductus arteriosus device occlusion

A 7-month-old patient in congestive heart failure due to a moderate sized patent ductus arteriosus (PDA) underwent uncomplicated implantation of an Amplatzer Ductal Occluder (ADO1). Two months after percutaneous device PDA closure, left pulmonary artery (LPA) stenosis was discovered. Rather than spontaneous improvement as reported in previous cases, our patient's LPA stenosis progressed in severity 7 months after ADO1 placement. A catheterization demonstrated a 32 mm Hg peak gradient from her main pulmonary artery to her LPA. She underwent successful stent angioplasty of her LPA with an excellent result and preserved PDA closure. This case demonstrates that stent angioplasty is a feasible an effective method of relieving LPA obstruction caused by a PDA occluder device. Additionally, despite slight deflection by the stent, the ADO1 device continued to provide complete ductal closure. Stent angioplasty should be considered in patients who have LPA stenosis caused by ADO1 occluder device that does not improve over time.

Transcatheter closure of large patent ductus arteriosus with severe pulmonary arterial hypertension: Short and intermediate term results

Objective:To assess the efficacy and safety of transcatheter closure (TCC) of patent ductus arteriosus (PDA) with severe pulmonary arterial hypertension (PHT).Background:TCC of small and moderate-sized PDAs is well established. However, there is a paucity of data on TCC of large PDA with severe PHT.Methods:This is a retrospective observational study of 76 patients with large PDA and severe PHT who were referred for TCC. Multiple clinical and investigational parameters were evaluated to decide the reversibility of PHT. Following the TCC, patients were serially followed up to assess the efficacy and safety of closure and its impact on PHT.Results:Of 76 patients, nine were found to have PDA with Eisenmenger's syndrome. Of remaining 67, two were thought to have irreversible PHT based on hemodynamic data obtained after balloon occlusion of the duct. Sixty five patients, who eventually underwent TCC of PDA, had a median age of 9.1 years (range 1 month to 40 years). The weight ranged between 2.5 to 62 kg (median 14 kg). The PDA size was 9.1 ± 4.6 mm. The mean systolic pulmonary artery pressure was 66.9 ± 15.3 mm Hg. Duct occluder was used in 63 and muscular ventricular septal defect closure device in 2. The follow up was available in 56 (86%) with a mean follow up period of 65 ± 34 months. All the patients had complete closure of the PDA at 6 months follow up. Mild obstruction of left pulmonary artery (n=3) and aortic isthmus flow (n=6) was noted at the time of discharge. During the follow up, partial or complete resolution of PHT was observed in all the patients in whom Doppler-derived right ventricular systolic pressure was recorded (available in 40 of 56 patients).Conclusions:TCC of large PDA with severe PHT and significant left to right shunt was found to be effective and safe in the short and intermediate term.

Differential activity of pro-angiogenic CXC chemokines

We showed previously in a mouse model of lung ischemia-induced angiogenesis, enhanced expression of the three ELR+ CXC chemokines (KC, LIX, and MIP-2) and that blockade of the ligand receptor CXCR2 limited neovascularization. The present study was undertaken to determine the relative abundance and angiogenic potential of the three CXC chemokines and whether RhoA activation explained the measured differences in potencies. We found that LIX showed the greatest absolute amount in the in vivo model 4 h after left pulmonary artery obstruction (LIX>KC>MIP-2; p<0.05). In vitro, LIX induced the greatest degree of arterial endothelial cell chemotaxis and KC was without effect. A significant increase (∼40%) in active RhoA was observed with both LIX and MIP-2 compared with vehicle control (p<0.05). On average, LIX induced the greatest amount of tube formation within pleural tissue in culture. Thus, the results of the present study suggest that among the three ELR+ CXC chemokines, LIX predominates in eliciting a pro-angiogenic phenotype.

The role of CXCR2in systemic neovascularization of the mouse lung

We previously showed increased expression of the ELR+, CXC chemokines in the lung after left pulmonary artery obstruction. These chemokines have been shown in other systems to bind their G protein-coupled receptor, CXCR(2), and promote systemic endothelial cell proliferation, migration, and capillary tube formation. In the present study, we blocked CXCR(2) in vivo using a neutralizing antibody and also studied mice that were homozygous null for CXCR(2). To estimate the extent of neovascularization in this model, we measured systemic blood flow to the left lung 14 days after left pulmonary artery ligation (LPAL). We found blood flow significantly reduced (67% decrease) with neutralizing antibody treatment compared with controls. However, blood flow was not altered in the CXCR(2)-deficient mice compared with wild-type controls after LPAL. To test for ligand availability, we measured macrophage inflammatory protein (MIP)-2 in lung homogenates after LPAL, because this is the predominant CXC chemokine previously shown to be increased after LPAL (22). MIP-2 protein was two- to fourfold higher in the left lung relative to the right lung in all treatment groups 4 h after LPAL and this increase did not differ among groups. We speculate that the CXCR(2)-deficient mice have compensatory mechanisms that mitigate their lack of gene expression and conclude that CXCR(2) contributes to chemokine-induced systemic angiogenesis after pulmonary artery obstruction.

Systemic neovascularization of the lung after pulmonary artery occlusion: “decoding the Da Vinci code”

Five hundred years ago, Leonardo da Vinci demonstrated that new bronchial vessels can develop in a human lung. The development of a mouse model of pulmonary artery obstruction in recent years ([1][1]) has provided substantial insight into the mechanisms and consequences of the systemic

Regression of postobstructive vasculopathy after revascularization of chronically obstructed pulmonary artery

ObjectivesPulmonary vascular resistance decreases dramatically after pulmonary thromboendarterectomy and further improves in time. This may reflect the slow regression of postobstructive pulmonary vasculopathy. We hypothesized that postobstructive pulmonary vasculopathy may regress after reperfusion in a piglet model of chronic (5 weeks) left pulmonary artery obstruction. MethodsThe ligated left pulmonary artery was reimplanted into the pulmonary arterial trunk. Pulmonary artery blood flow and pressure were measured 2 days and 5 weeks after reperfusion. Pulmonary artery smooth muscle thickness, endothelium-dependent relaxation, and left lung endothelial nitric oxide synthase activity and expression were assessed 5 weeks after ligation (n = 10) and 5 weeks after reperfusion (n = 10), and compared with a sham group (n = 10). Patency of the anastomoses and systemic blood supply to the lung were assessed by pulmonary angiography and nonselective thoracic aortography, respectively. ResultsAngiography showed that pulmonary artery anastomoses were patent in all animals. Five weeks after reperfusion, left pulmonary blood flows were similar to those in the sham animals, and systemic blood supply to the left lung decreased. Left pulmonary vascular resistance decreased by 50% at 5 weeks after reperfusion compared with 2 days after reperfusion (P = .0009). Medial muscle thickness of the left pulmonary artery greater than 600 μm increased 5 weeks after ligation and regressed to sham values 5 weeks after reperfusion (P = .001). Endothelium-dependent relaxation was only partially restored 5 weeks after reperfusion, whereas left lung endothelial nitric oxide synthase expressions and activities returned to sham values. ConclusionsThis study shows that postobstructive pulmonary vasculopathy induced by ligation of the pulmonary artery for 5 weeks regresses after reperfusion, accounting for the progressive improvement in hemodynamics after thromboendarterectomy.

Angiographic and hemodynamic predictors for successful outcome of transcatheter occlusion of patent ductus arteriosus in infants less than 8 kilograms.

Transcatheter occlusion of patent ductus arteriosus (PDA) using Gianturco coils (GCs) has been performed for the past decade. However, little has been written regarding anatomical and hemodynamic predictors for successful occlusion of the PDA in infants. This report is to evaluate the outcome of transcatheter occlusion of PDA in symptomatic infants less than 8 kg and to assess predictors of successful occlusion. Retrospective review of catheterization charts and cineangiograms of 42 symptomatic infants who underwent cardiac catheterization for attempted transcatheter occlusion of their PDA was conducted. The hemodynamic and angiographic data evaluated included the length/diameter (L/D) ratio, defined as the length divided by the narrowest diameter of the ductus arteriosus, and preocclusion pulmonary artery pressures. Thirty-one out of 42 patients (74%) had successful occlusion. Twenty-nine out of 42 infants had an L/D ratio > 3. Of these, 26 (90%) had successful occlusion of their PDA. Thirteen out of 42 patients had an L/D ratio < or = 3. Of these, 8 (62%) had unsuccessful occlusion. Complications encountered were transient loss of femoral arterial pulse (n = 6), coil embolization (n = 5), hemolysis (n = 2), and mild left pulmonary artery obstruction (n = 2). No permanent loss of femoral arterial pulse was noted. These complications resulted in no mortality and minimal morbidity. The L/D ratio was the strongest predictor of successful outcome, with an L/D ratio greater than 3.0 being more amenable to transcatheter occlusion (odds ratio of 4.6). Other predictors for success included lower preocclusion systolic, diastolic, and mean pulmonary artery pressure and smaller ductal diameter. Our conclusion was that infants less than 8 kg with an L/D ratio > 3.0 can safely and successfully undergo transcatheter occlusion of their PDA using transcatheter coils.

Left Pulmonary Artery Kinking Caused by Outflow Tract Dilatation After Transannular Patch Repair of Tetralogy of Fallot

Background. Stenosis of the branch pulmonary arteries after tetralogy of Fallot repair can result from several mechanisms. In patients with free pulmonary regurgitation and right ventricular dilatation after transannular patch repair, we have observed that the pulmonary outflow tract can dilate and elongate craniad and rotate to the left, resulting in kinking and obstruction of the previously normal left pulmonary artery. Methods. Ten patients referred for reoperation after tetralogy repair with severe pulmonary regurgitation and right ventricular outflow tract dilatation were found to have left pulmonary artery kinking. In 8 of these patients kinking was the sole or partial cause of left pulmonary artery obstruction, whereas there was no documented obstruction in the other 2. All patients underwent right ventricular outflow tract reconstruction and left pulmonary artery repair with removal of the redundancy at the kink point. Patching alone is not an effective method of repair in this condition, because the mechanism of obstruction is not corrected and the patch material can become redundant and lead to recurrent obstruction. Results. All patients underwent successful pulmonary outflow tract reconstruction. Left pulmonary artery kinking was corrected in all patients, and relief of obstruction was attained in the 8 patients with stenosis. At follow-up ranging from 9 to 58 months, no patient has evidence of recurrent left pulmonary artery stenosis. Conclusions. Left pulmonary artery kinking should be suspected at long-term follow-up after tetralogy repair in patients with significant pulmonary regurgitation and right-sided dilatation, even if previous evaluations showed no evidence of left pulmonary arterial abnormality. Because unilateral obstruction caused by kinking may lead to asymmetric pulmonary flow, it can exacerbate pulmonary regurgitation and right ventricular dilatation, in effect accelerating the processes that led to kinking in the first place. Kinking can be relieved successfully with the techniques described in this report.

Comparison between Three- and Four-Element Windkessel Models to Characterize Vascular Properties of Pulmonary Circulation

In 11 anaesthetised pigs the accuracy of the three-element (WK3) and the four-element (WK4) Windkessel models to describe hemodynamic properties of the pulmonary circulation was compared during six different experimental conditions increasing pulmonary arterial pressure: increase in left atrial pressure, increase in alveolar pressure, increase in pulmonary blood flow, endotoxin shock, mechanical obstruction of left pulmonary artery or histamine infusion. Our results showed that WK4 fitted better the data than did WK3 because values of 1- R 2 decreased from 6 percent (WK3) to 1.4 percent (WK4) when WK4 was used (P < 0.0005). 1- R 2 was an adequate marker of the accuracy of the linear regression used to solve equations of both models. Compliance values estimated by WK4 were decreased by 5% comparatively to WK3 (P = 0.008). However, this difference can be considered as not physiologically relevant. Values of characteristic resistance corresponding to R 1 + (L/R 2 C) in WK4 and to R 1 in WK3 were not different (P = 0.22). The relative changes in R 1, R 2, and C observed due to the different experimental conditions were comparable regardless of the model. In conclusion, the conversion of WK3 in WK4 by adding an inductance, whose physiological meaning is not clear, resulted in an increased statistical accuracy of the model, but did not seem to have relevant influence on parameters or their evolution during experimental conditions.

Transcatheter closure with single or multiple Gianturco coils of patent ductus arteriosus in infants weighing ≤8 kg: Retrograde versus antegrade approach

Experience with transcatheter closure (TCC) of patent ductus arteriosus (PDA) in small infants is limited. Our goals were to evaluate the immediate and short-term results of TCC of PDA in small infants (≤8 kg) as attempted with single or multiple Gianturco coils and to compare results for PDA ≤2.5 mm versus PDA >2.5 mm. Twenty-four infants underwent an attempt at TCC of PDA at a median age of 0.7 years (range 2 weeks to 1.5 years) and median weight of 6.5 kg (range 2.3 to 8 kg). Coils were placed by the transvenous route in 14 patients and by the transarterial route in 10 patients. The median PDA diameter was 2.7 mm (range 0.4 to 5.2 mm). Ten patients had PDA diameters <2.5 mm and all had complete closure, 9 with a single coil and 1 with two coils. Fourteen patients had PDA diameters ≥2.5 mm; closure was complete in 10 patients, 9 of whom required multiple coils. There was a trend toward improved results with multiple coils delivered transvenously. There was immediate complete closure of the PDA with a diameter as large as 5.2 mm that persisted at a median follow-up period of 1.2 year. Closure was unsuccessful in 4 patients, each of whom required multiple coils. The median fluoroscopy time was 19 minutes. Complications included transient loss of femoral pulse in 2 infants, mild left pulmonary artery obstruction in 2, and nonretrievable coil migration to the right lung in one. We conclude that TCC is effective therapy for small infants with a PDA of diameter ≤5.2 mm by the single- or multiple-coil technique on an outpatient basis and that TCC can be performed in neonates as small as 2.3 kg.

SECTION ON CARDIOLOGY 1996 ANNUAL MEETING PROGRAM

Background: Cardiac catheterization (CC) has been utilized with caution in children on extracorporeal membrane oxygenation (ECMO) due to concerns related to anticoagulation, however there have been no reports of procedure outcome in the literature. This retrospective review was performed to evaluate the indications and outcome of cardiac catheterization (CC) in this population. Methods: We reviewed the catheterization records, hospital charts, and follow up records of all children who have undergone this procedure at our institution from 12/90 to 12/95 (n=14). Records were reviewed to assess indications, results, and complications of CC, as well as clinical outcome. Results: Patients ranged in age from 3 days to 46 months, and diagnoses included single ventricle variants (7), tetralogy of Fallot or variant (4), and others (3). ECMO was utilized preoperatively in 2 pts, and postoperatively in 12 pts; indications for ECMO included low cardiac output or ventricular dysfunction (7), severe hypoxemia (4), and pulmonary hypertension (3). Indications for CC were diagnostic in 12 pts (coronary anatomy, pulmonary artery anatomy, pulmonary vein obstruction, pulmonary hypertension, and/or ventricular function), and interventional in 2 pts (balloon atrial septostomy and aortopulmonary collateral (APC) coil embolization). Two unplanned therapeutic procedures were also performed (coil embolization of APC in 1 pt and of a vertical vein in 1 pt). Adequate evaluation of clinical questions was accomplished in all pts. Unexpected diagnostic information of clinical importance was obtained in 5 pts, including right coronary artery obstruction, significant APC, a vertical vein from a pulmonary venous confluence, left pulmonary artery obstruction, and a restrictive ventricular septal defect causing subaortic obstruction.