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Biomedical subjects

L N Benson

Publications and source records attributed to L N Benson.

At least 55 records · Page 3Linked to original sources

Interventional cardiac catheterization.

Over the past decade, transcatheter interventions have become increasingly important in the treatment of patients with congenital heart lesions. These procedures may be broadly grouped as dilations (e.g., septostomy, valvuloplasty, angioplasty, and endovascular stenting) or as closures (e.g., vascular embolization and device closure of defects). Balloon valvuloplasty has become the treatment of choice for patients in all age groups with simple valvar pulmonic stenosis and, although not curative, seems at least comparable to surgery for congenital aortic stenosis in newborns to young adults. Balloon angioplasty is successfully applied to a wide range of aortic, pulmonary artery, and venous stenoses. Stents are useful in dilating lesions of which the intrinsic elasticity results in vessel recoil after balloon dilation alone. Catheter-delivered coils are used to embolize a wide range of arterial, venous, and prosthetic vascular connections. Although some devices remain investigational, they have been successfully used for closure of many arterial ducts and atrial and ventricular septal defects. In the therapy for patients with complex CHD, best results may be achieved by combining cardiac surgery with interventional catheterization. The cooperation among interventional cardiologists and cardiac surgeons was highlighted in a report of an algorithm to manage patients with tetralogy of Fallot or pulmonary atresia with diminutive pulmonary arteries, involving balloon dilation, coil embolization of collaterals, and intraoperative stent placement. In this setting, well-planned catheterization procedures have an important role in reducing the overall number of procedures that patients may require over a lifetime, with improved outcomes.

Adolescent↗

L-carnitine attenuates doxorubicin-induced lipid peroxidation in rats.

Doxorubicin (DOX) was administered intraperitoneally to rats in six equal, 2.5 mg/kg doses over a 2-week period with or without L-carnitine. Injury was monitored by echocardiography, release of myosin light chain-1 (MLC-1), and by measurement of aldehydic lipid peroxidation products. General observation revealed that DOX alone caused more ascites than DOX plus L-carnitine. Animals sacrificed 2 h after the sixth dose had significantly higher aldehyde concentrations than 2 h after a single dose of DOX. Aldehydes in plasma and heart remained elevated for 3 weeks after the final dose of DOX, whereas L-carnitine prevented or attenuated the DOX-induced increases in lipid peroxidation. The increase in MLC-1 2 h after the sixth dose of DOX was greater than after a single dose, suggesting cumulative damage. Echocardiography did not detect either early injury or the protective effects of L-carnitine. These data indicate that lipid peroxidation following DOX occurs early, and parallels the cumulative characteristics of DOX-induced cardiotoxicity. The protective effects of L-carnitine may be due to improved cardiac energy metabolism and reduced lipid peroxidation.

Aldehydes↗

Equivalent survival following cavopulmonary shunt: with or without the Fontan procedure.

OBJECTIVES: In 1992, an analysis of our experience with the cavopulmonary shunt (CPS) demonstrated equivalent long-term survival, with or without subsequent conversion to a Fontan circulation. Before 1992 (era 1) intervention was deferred until mandated by clinical deterioration. Since 1992 (era 2), timing of both CPS and Fontan was compressed in an effort to improve survival. Survival following CPS is analyzed to ascertain whether Fontan confers any survival advantage over no further definitive intervention. METHODS: From 1962 to 1997 inclusive, 490 patients underwent CPS, excluding those who had a CPS concomitant with a Fontan. In 55 patients the CPS was performed at or after a biventricular repair (BVR), or after a Fontan, and these patients are excluded. The 435 patients remaining followed a surgical protocol which included a subsequent BVR (n = 28), or a subsequent Fontan operation (n = 220), or no further definitive surgery (CPS only, n = 187). Between eras the mean age at surgery decreased for all procedures. RESULTS: Long-term survival 20 years after a CPS in 435 patients is 56 +/- 5%. Survival at 20 years among the 220 patients who were subsequently converted to a Fontan circulation is 65 +/- 8% compared to 50 +/- 11% for the 187 patients who did not have a Fontan. However, most of their survival difference is because all early deaths after a CPS occurred in the non-Fontan group. Multivariable analysis demonstrated that proceeding to a Fontan did have a small survival advantage which was not evident by univariate analysis. Independent risk factors for death, at any time, are a common atrioventricular valve, or pulmonary artery banding. The era had no effect on survival. CONCLUSIONS: The single ventricle circulation appears to have a limited durability of, an average, 30-40 years. There is a slight survival advantage in converting patients after a CPS to a Fontan circulation. A marked reduction in age at CPS and at Fontan has, as yet, not improved survival.

Adolescent↗

Clinical outcomes of acute myocarditis in childhood.

OBJECTIVE: To describe clinical outcomes of a paediatric population with histologically confirmed lymphocytic myocarditis. DESIGN: A retrospective review between November 1984 and February 1998. SETTING: A major paediatric tertiary care hospital. PATIENTS: 36 patients with histologically confirmed lymphocytic myocarditis. MAIN OUTCOME MEASURES: Survival, cardiac transplantation, recovery of ventricular function, and persistence of dysrhythmias. RESULTS: Freedom from death or cardiac transplantation was 86% at one month and 79% after two years. Five deaths occurred within 72 hours of admission, and one late death at 1.9 years. Extracorporeal membrane oxygenation support was used in four patients, and three patients underwent heart replacement. 34 patients were treated with intravenous corticosteroids. In the survivor/non-cardiac transplantation group (n = 29), the median follow up was 19 months (range 1.2-131.6 months), and the median period for recovery of a left ventricular ejection fraction to > 55% was 2.8 months (range 0-28 months). The mean (SD) final left ventricular ejection and shortening fractions were 66 (9)% and 34 (8)%, respectively. Two patients had residual ventricular dysfunction. No patient required antiarrhythmic treatment. All survivors reported no cardiac symptoms or restrictions in physical activity. CONCLUSIONS: Our experience documents good outcomes in paediatric patients presenting with acute heart failure secondary to acute lymphocytic myocarditis treated with immunosuppression. Excellent survival and recovery of ventricular function, with the absence of significant arrhythmias, continued cardiac medications, or restrictions in physical activity were the normal outcomes.

Acute Disease↗

Closure of persistently patent arterial duct and its impact on cerebral circulatory haemodynamics in children.

PURPOSE: Closure of a patent arterial duct (PDA) is suggested as a risk factor associated with intraventricular haemorrhage and/or cerebral ischemia in neonates. This study evaluate the effects of transcatheter closure of a patent arterial duct in children on cerebral blood flow velocity. METHODS: Twelve children, aged from one to eight years were enrolled. Anaesthesia induction consisted of thiopentone, fentanyl and diazepam. Tracheal intubation was facilitated with vecuronium. Anaesthesia was maintained with N2O 70% in O2 and a PaCO2 between 35 to 40 mmHg. No cerebral vasoactive agents were used. Mean arterial pressure (MAP), central venous pressure (CVP), heart rate were continuously recorded. Systolic (Vs) and diastolic (Vd) cerebral blood flow velocity (CBFV) were recorded. Cerebral perfusion pressure (CPP) was calculated. The mean CBFV, the systolic-mean ratio and the cerebral blood volume were estimated from the area under the velocity-time curve (AUC) before PDA closure, immediately after and for 10 min following occlusion. RESULTS: The mean (+/- SD) age and weight were 30 +/- 22 mo and 13 +/- 5 kg, respectively. Continuous recording during duct closure showed an abrupt increase in Vd (P < 0.05) whereas Vs remained constant. The AUC increased after closure and persisted for 10 min (P < 0.05). CONCLUSION: This study confirms that closure of a PDA leads to acute changes in intracerebral diastolic flow and volume. This observation gives weight to mechanisms involved in IVH in smaller infants after arterial surgical duct closure. The anaesthetic technique used for arterial duct closure in these procedure could influence these observations.

Area Under Curve↗

Brain damage and myocardial dysfunction: protective effects of magnesium in the newborn pig.

BACKGROUND: Brain damage is associated with myocardial dysfunction resulting from excessive release of endogenous catecholamines and Ca2+ overload. Magnesium ion, a natural Ca2+ blocker, has recently been recognized as a myoprotective agent. METHODS: Myocardial function was assessed in 3- to 7-day-old piglets from pressure-volume data (obtained by the conductance catheter/micromanometer technique) before and for 4 hours after ligation of the aortic arch vessels and was correlated with ultrastructural changes. Group a (n = 6) received MgSO4 immediately after induction of brain damage for 4 hours, whereas group b (n = 6) did not receive MgSO4 and served as control. RESULTS: In both groups after induction of brain damage, there was a significant (p < 0.05) increase in end-systolic elastance and preload-recruitable stroke work that persisted for 1 hour. However, after 2 and 4 hours, there was a significant (p < 0.05) reduction in both variables in group b (end-systolic elastance, 74% +/- 5% and 59% +/- 6%, respectively, and preload-recruitable stroke work, 77% +/- 4% and 64% +/- 3%, respectively, compared with baseline), and in group a, the values returned to baseline. The chamber stiffness index rose significantly (p < 0.05) in group b 15 minutes after induction of brain damage and remained significantly (p < 0.05) higher for 4 hours versus no significant change in group a. Plasma levels of epinephrine and norepinephrine were similar in the groups before and after brain damage. Electron microscopic study showed severe ultrastructural changes in group b and significantly milder changes in group a. CONCLUSIONS: We conclude that MgSO4 may protect the neonatal myocardium when administered immediately after brain damage.

Adrenergic Agonists↗

The physiology of the bidirectional cavopulmonary connection.

This article reviews the indications for the bidirectional cavopulmonary connection and demonstrates its efficacy in reducing mortality for the Fontan procedure. The indications for adding an additional source of pulmonary blood flow to the bidirectional cavopulmonary connection are discussed, but this issue remains controversial. Also unclear is whether the bidirectional cavopulmonary connection promotes symmetric growth of the pulmonary arteries, or whether growth of the left pulmonary artery is disadvantaged. Finally, systemic venous collateralization is a well-recognized sequel after cavopulmonary connection. The clinical implications of this collateralization are reviewed.

Anastomosis, Surgical↗

Diagnosis and management of stenotic aorto-arteriopathy in childhood.

Stenotic aorto-arteriopathy is an uncommon vascular lesion characterized by segmental arterial stenoses. We reviewed the experience with several management algorithms to define the most effective management course. The clinical records of 14 pediatric patients with acquired SAA who presented over a 16-year period were reviewed. Most patients presented with a mid-thoracoabdominal coarctation and were diagnosed with Takayasu arteritis. Differentiating between Takayasu arteritis and fibromuscular dysplasia was difficult on clinical grounds or by angiography. Medical management of the end-organ disease and renovascular hypertension was only palliative. Selective percutaneous transluminal balloon angioplasty of the stenotic renal arteries had only transient benefits; renal autotransplantation had slightly better success. Dilation of stenosed aortic segments with balloon-expandable endovascular stents and subsequent renal autotransplantation proved useful. Distinguishing SAA resulting from fibromuscular dysplasia caused by Takayasu arteritis in the chronic vaso-occlusive phase may be unnecessary for effective treatment. Therapy should focus on interventions to minimize the end-organ damage caused by the vaso-occlusive manifestations of the disorders.

Adolescent↗

Assessment of myocardial perfusion and function in childhood systemic lupus erythematosus.

OBJECTIVES: To determine the prevalence of abnormalities in myocardial perfusion or function in children with systemic lupus erythematosus (SLE), and describe potential factors that may predict their development. STUDY DESIGN: Patients (n = 40; 30 female) were enrolled through the Lupus Clinic at The Hospital for Sick Children between 1990 and 1992. Resting and exercise thallium myocardial perfusion scans, radionuclide angiography with multiple gated acquisition (MUGA), and resting M-mode and two-dimensional echocardiography were performed. RESULTS: All patients were free of symptoms, and none had a history of ischemic heart disease. Their median age was 15.9 years (range 10.5 to 19.8 years) at enrollment. Abnormalities of coronary perfusion were found in 5 (16%) of 31 patients (95% confidence interval: 3%, 29%) and included a large fixed perfusion defect in 1; 5 of 27 MUGA scans showed marginally low left ventricular ejection fractions at rest, whereas all had normal exercise responses. In the group with abnormal thallium scans, three of five patients had antiphospholipid antibodies detected, and two of four had an abnormal plasma lipid profile. This group tended to have a shorter disease duration and had received a lower cumulative dose of corticosteroids; these differences were not statistically significant compared with the group with normal scans. CONCLUSION: Asymptomatic abnormalities of myocardial perfusion occur in children with SLE and are more common than previously suspected. Patients with these abnormalities of myocardial perfusion may be predisposed to the previously recognized early-onset ischemic heart disease seen in adults with SLE.

Adolescent↗

Fate of the neopulmonary valve after the arterial switch operation in neonates.

OBJECTIVES: The purpose of this study was to determine the incidence, risk factors, and outcomes of acquired stenosis of the neopulmonary valve after the neonatal arterial switch operation. METHODS: Reviewed were the preoperative and follow-up echocardiograms from 136 of 288 patients undergoing the arterial switch operation for whom adequate studies were available. Pulmonary stenosis was defined as a thickened and doming pulmonary valve and a pressure gradient of 20 mm Hg or more. Transposition of the great arteries was present with intact ventricular septum in 91 patients, with a ventricular septal detect in 39, with an aortic coarctation in 5, and with double-outlet right ventricle in 1 patient. No patient had preoperative valvular abnormalities (i.e., a bicuspid valve). RESULTS: During a median follow-up of 18 months (range <1 to 90 months), 32 patients (24%) had the development of supravalvular pulmonary stenosis, 15 (11%) with associated pulmonary valve stenosis (group I). Kaplan-Meier estimates of freedom from any intervention were 94% (95% confidence interval, 90% to 99%) at 1 year and 79% (95% confidence interval, 64% to 94%) at 5 years. The valve anulus before the arterial switch operation was significantly larger (p < 0.03) in those in whom neopulmonary valve stenosis did not develop (group II) than it was in those in whom it did (group I). At follow-up, the pulmonary valve anulus had decreased significantly in diameter in group I (p < 0.0005) and had remained larger in group II (p = 0.06) compared with normal diameter. Group I patients had the development of significant pulmonary valve hypoplasia (p < 0.03) whereas group II patients continued to have significantly larger valves compared with normal size (p < 0.0001). CONCLUSIONS: Neopulmonary valve stenosis after the arterial switch operation is not uncommon and is associated with growth failure of the valve anulus often associated with supravalvular pulmonary stenosis.

Female↗

Systemic venous collateral development after the bidirectional cavopulmonary anastomosis. Prevalence and predictors.

OBJECTIVES: To determine the prevalence of systemic venous collaterals after the bidirectional cavopulmonary anastomosis and the factors associated with their development. BACKGROUND: Systemic venous collaterals have been found after cavopulmonary anastomosis. Methods. Cardiac catheterization was performed in 103 patients before and after a bidirectional cavopulmonary anastomosis. RESULTS: After surgery, 51 venous collaterals were identified in 32 patients (31%). Collateral development was associated with an abnormal superior vena caval connection (56% incidence vs. 26% with a single right superior vena cava, p = 0.01) and postoperative factors including pulmonary artery distortion (53% incidence vs. 22% without distortion, p = 0.002); increased superior vena caval mean pressure (14 +/- 5 mm Hg versus 11 +/- 4 mm Hg with no collaterals, p = 0.0002); increased pulmonary artery mean pressure (13 +/- 4 mm Hg vs. 11 +/- 4 mm Hg with no collaterals, p = 0.02); lower right atrial mean pressure (5 +/- 2 mm Hg vs. 6 +/- 3 mm Hg with no collaterals, p = 0.04); and increased mean gradient between superior vena cava and right atrium (8 +/- 3 mm Hg vs. 5 +/- 4 mm Hg with no collaterals, p = 0.0002). Using multiple logistic regression, only this last factor was independently associated with collateral development with an odds ratio per 1 mm Hg of 1.33 (95% CI 1.12-1.58, p = 0.001) for their presence. CONCLUSIONS: Systemic venous collaterals occur frequently after a bidirectional cavopulmonary anastomosis and are found postoperatively when a significant pressure gradient occurs between cava and right atrium.

Adolescent↗

Complications associated with pediatric cardiac catheterization.

OBJECTIVES: The aim of this study was to determine the relative risks of pediatric diagnostic, interventional and electrophysiologic catheterizations. BACKGROUND: The role of the pediatric catheterization laboratory has evolved in the last decade as a therapeutic modality, although remaining an important tool for anatomic and hemodynamic diagnosis. METHODS: A study of 4,952 consecutive pediatric catheterization procedures was undertaken. RESULTS: Patient ages ranged from 1 day to 20 years (median 2.9 years). One or more complications occurred in 436 studies (8.8%) and were classified as major in 102 and minor in 458, with vascular complications (n=189; 3.8% of procedures) the most common adverse event. Arrhythmic complications (n=24) were the most common major complication. Death occurred in seven cases (0.14%) as a direct complication of the procedure and was more common in infants (n=5). Independent risk factors for complications included a young patient age and undergoing an interventional procedure. CONCLUSIONS: Complications continue to be associated with pediatric cardiac catheterization. Efforts should be directed to improving equipment for flexibility and size, and finding alternative methods for vascular access. Patient age and interventional studies are risk factors for morbidity and mortality.

Adolescent↗

Long-term outcome and prognostic determinants in children with hypertrophic cardiomyopathy.

OBJECTIVES: We sought to determine clinical, angiographic, and echocardiographic predictors of survival in children with isolated hypertrophic cardiomyopathy (HCM) in a large pediatric centre. BACKGROUND: Sudden death is a catastrophic outcome of HCM in childhood but has been difficult to predict. Current therapies might provide for improved outcome if factors identifying high risk can be identified. METHODS: Records of 99 patients diagnosed with HCM from 1958 to 1997 at <18 yr were reviewed for clinical, angiographic (n = 62) and echocardiographic (n = 83) predictors of survival outcome. The effects of clinical characteristics on sudden death (including resuscitated sudden death) were individually tested in Cox's proportionate hazard modeling. RESULTS: Seventy-one subjects were male. Median age at diagnosis was 5.0 yr with a medical follow-up interval of 4.8 yr. Thirty-seven of 97 patients had a family history of HCM. Ambulatory electrocardiograms (ECG) in 78 patients demonstrated supraventricular tachycardia in 16 and ventricular tachycardia in 21. Death or resuscitated sudden death occurred in 18 patients. Sudden death rate was 2.7%/yr after age 8 yr. Cox's proportionate survival modeling revealed increased corrected QT interval (QTc) dispersion on ECG (relative risk [RR] 1.61 per 20 ms increment, p < 0.0003), ventricular tachycardia (VT) on ambulatory ECG (RR 3.75, p < 0.006) and myocardial bridging of the LAD coronary (RR 12.0, p < 0.003) to be associated with reduced time to death or resuscitated sudden death. CONCLUSIONS: Detailed assessment of ECGs, ambulatory ECGs, and coronary angiography can assist in identifying which children with HCM are at risk for sudden death.

Adolescent↗

Impact of dynamic 3D transoesophageal echocardiography in the assessment of atrial septal defects and occlusion by the double-umbrella device (CardioSEAL)

Occlusion of the atrial septal defects in the oval fossa by interventional catheterization has progressed, but still has limitations. Three-dimensional (3D) echocardiography can provide unique views unavailable by cross-sectional imaging. The objective of this study was to define the clinical application of 3D echocardiography in the assessment and monitoring of transcatheter occlusion of atrial septal defects. Three-dimensional echocardiography was attempted prior to occlusion of atrial septal defects in 41 patients (median age 8.6 years). Serial cross-sectional images were acquired by multiplane transoesophageal echocardiography and displayed by means of computer reconstruction. Dynamic 3D echocardiographic images of defects in the oval fossa were obtained in 40 of 41 patients (98%). Volume-rendering demonstrated the anterosuperior rim in 36 (90%) and the inferoposterior rim in 24 (60%), but failed to reveal small additional fenestrations in six. Sizes measured by 3D echocardiography were significantly larger than those provided by cross-sectional transoesophageal echocardiography (p=0.007), but differed little from those obtained with balloon sizing (p=0.6). After occlusion, 3D echocardiography showed positions of all arms of the device in 20 of 24 cases. Location of any protruding arms, or residual defects, were also clearly revealed. Three-dimensional images obtained in 12 patients during deployment of the double-umbrella device were useful in monitoring its position (single-frame) and for explaining the mechanism of protrusion. Current 3D echocardiography provides clinically relevant information for selection of patients for closure of atrial septal defects by interventional catheterization and when monitoring during implantation. Information obtained by this technique can clarify the mechanism of deployment of the device and closure of the defect, therefore influencing outcomes.

Adolescent↗

Left ventricular hemodynamics in anemic fetal lambs.

OBJECTIVE: To assess the left ventricular determinants of cardiac output in 12 chronically instrumented fetal lambs, six of which where made anemic. METHODS: Twelve, singleton pregnant ewes were instrumented between 123-126 days gestation and chronic catheters placed in-situ. In six fetal lambs, isovolemic fetal anemia was induced (reducing the hematocrit from a mean of 35% to 20%). In a prospective study, absolute 'beat-to-beat' LV volumes and pressures were obtained (gestational age 131-134 days) using a conductance catheter method and a comparison made with non-anemic fetal lambs. RESULTS: The group of anemic fetuses (n = 6) had a significantly reduced hematocrit as compared to the control group (37% decrease: mean difference--13.4%; P < 0.001). The arterial blood gases of the two groups were not statistically different, with the exception of the pO2 and oxygen content which were significantly lower in the anemic group (P < 0.05). There was no significant change in fetal heart rate, LV preload (as assessed by venous pressure, end-diastolic volume and pressure) or mean arterial pressure between the anemic and control groups. However, a 75% increase in LV stroke volume was observed in the anemic fetal lambs (P < 0.05), secondary to a 61% fall in LV afterload (P < 0.05). There was no significant change in inherent myocardial contractility of the LV, although this did increase to approach statistical significance in the anemic group (P = 0.056). The diastolic time interval was increased by 22% in the anemic fetus, possibly allowing prolonged LV filling time. The indices measuring LV relaxation (Tau and dP/dtmin) were not significantly different in either group. CONCLUSIONS: This is the first study to report absolute left ventricular volumes in the anemic ovine fetus and the relationship of these data to LV pressure during the cardiac cycle. The model used produces a state of moderately severe, non-hydropic, isovolemic, fetal anemia consistent with those previously described. Although the anemic state was not prolonged, an observed increase in LV stroke volume (which is predominantly due to a decrease in afterload) has been described.

Anemia↗

Experimental branch pulmonary artery stenosis angioplasty using a novel cutting balloon.

To determined the safety and efficacy of a bladed balloon in the treatment of branch pulmonary artery stenosis, a model of left pulmonary artery stenosis was surgically created in two-week-old pigs. Seven pigs underwent angioplasty, five with the bladed balloon and two with conventional balloons. Overall, acute results showed a fall in the peak systolic pressure gradients from 8.3 +/- 2.3 mmHg to 3.2 +/- 3.1 mmHg and an increase in the minimum stenotic diameters from 4.5 +/- 2mm to 5.6 +/- mm. Acute pathological examination after cutting angioplasty showed regular luminal cuts that healed completely by four to six weeks in chronically surviving animals. Two of three surviving animals had persistent vessel enlargement at follow-up with one showing little overall change. Cutting balloons are effective in branch pulmonary artery angioplasty and may have clinical applications.

Angioplasty, Balloon↗

Doxorubicin-induced acute changes in cytotoxic aldehydes, antioxidant status and cardiac function in the rat.

Doxorubicin (DOX)-induced cardiotoxicity is thought to be caused by free radical-mediated mechanisms. An in vivo rat model was developed to investigate the DOX-induced cascade of early biochemical changes focusing on the central role of the aldehydic lipid peroxidation products. Antioxidant status was evaluated by glutathione measurements. Creatine Kinase (CK) activity was measured as an index of cardiac injury. Development of functional abnormalities were documented by echocardiography. The results showed that aldehydes in rat plasma and heart tissues increased significantly following DOX treatment. The changes occurred early, peaked around 2 h after DOX administration, and the levels declined or returned to baseline value within 8-24 h. Toxic aldehyde levels including malondialdehyde, hexanal and 4-hydroxy-non-2-enal also increased. Acyloin levels, metabolic products of aldehydes, increased early and then decreased in plasma, and there was a significant decrease in heart tissues after DOX treatment. GSH levels decreased early, then increased by 24 h, while GSSG levels decreased initially, then increased after DOX treatment, suggesting early depletion of GSH and a later rebound phenomenon. CK levels were elevated after treatment. The functional abnormalities were documented by stress echocardiography in some rats although the changes were not consistent at such an early stage following treatment. Our data confirmed the involvement of free radicals, and suggested that the cytotoxic aldehydes play a central role in initiating the steps that lead to functional impairment of the myocardium following DOX administration. Scavengers and the metabolic removal of some of the aldehydes also play a role in protecting the myocardium against injury.

Aldehydes↗

Transcatheter perforation of the right ventricular outflow tract as initial therapy for pulmonary valve atresia and intact ventricular septum in the newborn.

The clinical impact of transcatheter perforation and dilatation of the right ventricular outflow tract in neonates with pulmonary atresia and intact ventricular septum was reviewed. Between April 1992 and December 1994, 8 neonates underwent transcatheter perforation of the right ventricular outflow tract. Radiofrequency energy was employed in 6 patients and wire perforation in 2 patients. Mean patient age at intervention was 1.9 +/- 0.6 days and weight 3.4 +/- 0.5 kg. Median tricuspid valve annulus was 10.9 mm (range: 4.0-13.0 mm) and Z-value -0.85 (range: -4.5-1.0). The mean right ventricular systolic pressure fell from 117 +/- 16 to 55 +/- 15 mm Hg (P < 0.0001), and the right ventricular to aortic pressure ratio decreased from 1.81 +/- 0.33 to 0.82 +/- 0.28 (P < 0.0001). The arterial duct was patent in all. No acute complications occurred. Aortopulmonary shunts were performed in 7 patients at a median 6 days (range: 3-23 days) following catheterization. One patient developed sepsis and died after surgical resection of infected tissue, while a second patient died of a blocked aortopulmonary shunt 17 months following discharge. Median follow-up for the 6 surviving patients was 8 months (range: 4-32 months). One patient has achieved and a second is awaiting biventricular repair. Transcatheter perforation appears to be a promising form of therapy in selected patients with pulmonary atresia, and potentially facilitates algorithms leading to a biventricular repair.

Angioplasty, Balloon↗