Elimination of Yellow Phase: An Effective Method to Achieve High Quality HC(NH2 )2 PbI3 -based Perovskite Films.

Formamidinium lead iodide-based (FAPbI3 ) perovskite is widely used in the field of photovoltaics, owing to its suitable bandgap (ca. 1.45 eV) and better thermal stability. FAPbI3 has two polymorphs (black α-FAPbI3 and yellow δ-FAPbI3 ) at ambient temperature. The yellow δ-FAPbI3 , which has no photoactivity, has a chain-like structure that likely hinders electron transport and reduces photovoltaic performance. However, pure-phase black α-FAPbI3 without any yellow phase is difficult to obtain and the underlying mechanism of the phase transition is rarely investigated. In this study, a facile bi-additive method (BA method) has been developed to completely eliminate the yellow δ-FAPbI3 phase by inducing a phase transition from δ-FAPbI3 to α-FAPbI3 . HI and Pb(SCN)2 were employed as dual additives. Based on the investigation of the annealing time and temperature, we determined that the BA method can induce the phase transition and enhance the stability of α-FAPbI3 . Owing to the enhanced crystallization as well as uniform morphology of the BA film, the perovskite solar cells (PSCs) exhibited an increased power conversion efficiency (PCE). Furthermore, the optimal devices displayed excellent stability and maintained over 80 % of initial PCE after aging for 400 h in air. This work provides a new insight into the fabrication of high-quality pure α-FAPbI3 perovskite films and makes high efficiency photovoltaic devices a reality.

Lower risk of postoperative arrhythmias in congenital heart surgery following intraoperative administration of magnesium.

OBJECTIVES: Postoperative arrhythmias are common in children undergoing congenital heart surgery. We evaluated whether intraoperative administration of magnesium was associated with a reduced occurrence of specific postoperative arrhythmias, as has been described previously, or had a broader effect on multiple arrhythmia types, and whether there existed a dose-effect of intraoperative magnesium. METHODS: We used a historical prospective observational cohort study. Propensity score matching using logistic regression was applied to establish similar populations of treatment groups balanced on 5 important covariates. RESULTS: Based on propensity score-matched groups, magnesium 50 mg/kg administration was associated with a reduced odds of occurrence of postoperative arrhythmias: any arrhythmia (odds ratio [OR] = 0.50, P < .001), junctional ectopic tachycardia (OR = 0.56, P = .004), accelerated junctional rhythm (OR = 0.56, P = .089), atrial tachycardia (OR = 0.48, P = .005), ventricular tachycardia (OR = 0.52, P = .04), and atrioventricular block (OR = 0.47, P = .03). The effect of magnesium on reducing the odds of occurrence of postoperative arrhythmias did not differ between 25 mg/kg versus 50 mg/kg. CONCLUSIONS: As many as one third of our patients undergoing congenital heart surgery had postoperative arrhythmias. Use of intraoperative magnesium was associated with a reduction in the odds of occurrence of all postoperative arrhythmias. Our results do not provide evidence that a greater dose of magnesium is associated with greater arrhythmia risk reduction. Despite the intraoperative use of magnesium, there continued to be a high residual incidence of postoperative arrhythmias, raising the question for studying new or additional agents.

Pump in Parallel-Mechanical Assistance of Partial Cavopulmonary Circulation Using a Conventional Ventricular Assist Device.

Mechanical assistance of systemic single ventricle is effective in pulling blood through a cavopulmonary circuit. In patients with superior cavopulmonary connection, this strategy can lead to arterial desaturation secondary to increased inferior caval flow. We hypothesized that overall augmentation in cardiac output with mechanical assistance compensates for the drop in oxygen saturation thereby maintaining tissue oxygen delivery (DO2). Bidirectional Glenn (BDG) was established in seven swine (25 kg) after a common atrium had been established by balloon septostomy. Mechanical circulatory assistance of the single ventricle was achieved using an axial flow pump with ventricular inflow and aortic outflow. Cardiac output, mean pulmonary artery pressure (PAP), common atrial pressure (left atrial pressure [LAP]), arterial oxygen saturation (SaO2), partial pressure of arterial oxygen (PaO2), and DO2 were compared between assisted and nonassisted circulation. Significant augmentation of cardiac output was achieved with mechanical assistance in BDG circulation (BDG: median [interquartile range {IQR}], 0.8 [0.9-1.15] L/min versus assisted BDG: median [IQR], 1.5 [1.15-1.7] L/min; p = 0.05). Although oxygen saturations and PaO2 trended to be lower with assistance (SaO2; BDG: median [IQR], 43% [32-57%]; assisted BDG: median [IQR], 32% [24-35%]; p = 0.07) (PaO2; BDG: median [IQR], 24 [20-30] mm Hg; assisted BDG: median [IQR], 20 [17-21] mm Hg; p = 0.08), DO2 was unchanged with mechanical assistance (BDG: median [IQR], 94 [35-99] ml/min; assisted BDG: median [IQR], 79 [63-85] ml/min; p = 0.81). No significant change in the LAP or PAP was observed. In the setting of superior cavopulmonary connection/single ventricle, the systemic ventricular assistance with a ventricular assist device (VAD) leads to increase in cardiac output. Arterial oxygen saturations however may be lower with mechanical assistance, without any change in DO2.

Selective autonomic stimulation of the AV node fat pad to control rapid post-operative atrial arrhythmias.

Junctional ectopic tachycardia (JET) and atrial fibrillation (AF) occur in patients recovering from open-heart surgery (OHS). Pharmacologic treatment is used for the control of post-operative atrial arrhythmias (POAA), but is associated with side effects. There is a need for a reversible, modulated solution to rate control. We propose a non-pharmacologic technique that can modulate AV nodal conduction in a selective fashion. Ten mongrel dogs underwent OHS. Stimulation of the anterior right (AR) and inferior right (IR) fat pad (FP) was done using a 7-pole electrode. The IR was more effective in slowing the ventricular rate (VR) to AF (52 +/- 20 vs. 15 +/- 10%, p = 0.003) and JET (12 +/- 7 vs. 0 +/- 0%, p = 0.02). Selective site stimulation within a FP region could augment the effect of stimulation during AF (57 +/- 20% (maximum effect) vs. 0 +/- 0% (minimum effect), p<0.001). FP stimulation at increasing stimulation voltage (SV) demonstrated a voltage-dependent effect (8 +/- 14% (low V) vs. 63 +/- 17 (high V) %, p<0.001). In summary, AV node fat pad stimulation had a selective effect on the AV node by decreasing AV nodal conduction, with little effect on atrial activity.

Palliation of Truncus Arteriosus Associated With Complete Atrioventricular Canal--Results of Single Ventricle Palliation.

BACKGROUND: Truncus arteriosus associated with complete atrioventricular canal defect is rare and continues to be a surgical challenge with high morbidity and mortality. In the absence of extension of the ventricular septal defect to the outlet septum, biventricular repair is precluded, and single ventricle palliation remains the only option. We present our experience with five patients with truncus arteriosus and complete atrioventricular canal defect who underwent single ventricular palliation. METHODS: Five patients with truncus arteriosus and complete atrioventricular canal defect managed along the single ventricle palliation pathway were retrospectively reviewed. Demographic, echocardiographic, cardiac catheterization, and perioperative data were analyzed. RESULTS: All patients underwent neonatal palliation tailored to their anatomy (excision of pulmonary arteries from the common trunk and systemic to pulmonary artery shunt in two patients, excision of pulmonary artery and right ventricle to pulmonary artery conduit in two patients, and bilateral branch pulmonary artery bands in one patient). There were two early deaths after neonatal palliation. At a median follow-up of 210 days (interquartile range 1,210 days), all three survivors have undergone second-stage palliation. Of these patients, one is interstage II to III, and two patients have completed their Fontan procedure and are doing well. CONCLUSION: Truncus arteriosus with complete atrioventricular canal defect is a rare combination of defects. Single ventricle palliation pathway with a tailored neonatal approach may be employed for patients with uncommitted ventricular septal defects.

Magnesium Lowers the Incidence of Postoperative Junctional Ectopic Tachycardia in Congenital Heart Surgical Patients: Is There a Relationship to Surgical Procedure Complexity?

Magnesium sulfate was given to pediatric cardiac surgical patients during cardiopulmonary bypass period in an attempt to reduce the occurrence of postoperative junctional ectopic tachycardia (PO JET). We reviewed our data to evaluate the effect of magnesium on the occurrence of JET and assess a possible relationship between PO JET and procedure complexity. A total of 1088 congenital heart surgeries (CHS), performed from 2005 to 2010, were reviewed. A total of 750 cases did not receive magnesium, and 338 cases received magnesium (25 mg/kg). All procedures were classified according to Aristotle score from 1 to 4. Overall, there was a statistically significant decrease in PO JET occurrence between the two groups regardless of the Aristotle score, 15.3 % (115/750) in non-magnesium group versus 7.1 % (24/338) in magnesium group, P < 0.001. In the absence of magnesium, the risk of JET increased with increasing Aristotle score, P = 0.01. Following magnesium administration and controlling for body weight, surgical and aortic cross-clamp times in the analyses, reduction in adjusted risk of JET was significantly greater with increasing Aristotle level of complexity (JET in non-magnesium vs. magnesium group, Aristotle level 1: 9.8 vs. 14.3 %, level 4: 11.5 vs. 3.2 %; odds ratio 0.54, 95 % CI 0.31-0.94, P = 0.028). Our data confirmed that intra-operative usage of magnesium reduced the occurrence of PO JET in a larger number and more diverse group of CHS patients than has previously been reported. Further, our data suggest that magnesium's effect on PO JET occurrence seemed more effective in CHS with higher levels of Aristotle complexity.

Congenital aneurysm of the aortomitral intervalvular fibrosa.

A 5-year-old boy was found to have a congenital left ventricular outflow tract (LVOT) aneurysm of the intervalvular fibrosa, LVOT obstruction after repair of a perimembranous ventricular septal defect, and aortic coarctation. The patient underwent successful plication of the aneurysm, resection of the fibrous subaortic stenosis, and septal myectomy.

Effect of mechanical assistance of the systemic ventricle in single ventricle circulation with cavopulmonary connection.

BACKGROUND: Previous attempts to support single ventricle circulation mechanically have suggested that a custom-built assist device is needed to push, rather than pull, through the pulmonary circulation. We hypothesized that using a conventional ventricular assist device, with or without conversion of a total cavopulmonary connection to a bidirectional Glenn cavopulmonary connection, would allow assistance by pulling blood through the circuit and improve the cardiac index (CI). METHODS: Cavopulmonary connections were established in each of 5 Yorkshire pigs (25 kg) using ePTFE conduits in a Y configuration with appropriate clamping of the limbs of the Y to achieve a total cavopulmonary Fontan connection (TCPC), superior vena cava cavopulmonary connection (SVC Glenn), and inferior vena cava cavopulmonary connection (IVC Glenn). A common atrium had been established previously by balloon septostomy. Mechanical circulatory assistance of the single systemic ventricle was achieved using a centrifugal pump with common atrial inflow and proximal ascending aortic outflow. The CI was calculated using an ultrasonic flow meter placed on the distal ascending aorta and compared between the assisted and nonassisted circulation for 3 conditions: TCPC, SVC Glenn, and IVC Glenn. The mean pulmonary artery pressure, common atrial pressure, arterial oxygen saturation, partial pressure of arterial oxygen, and oxygen delivery were calculated. RESULTS: The unassisted SVC Glenn CI tended to be greater than the TCPC or IVC Glenn CI. Significant augmentation of total CI was achieved with mechanical assistance for SVC Glenn (109% ± 24%, P = .04) and TCPC (130% ± 109%, P = .01). The assisted CI achieved at least a mean baseline biventricular CI for all 3 support modes. Oxygen delivery was greatest for assisted SVC Glenn (1786 ± 1307 mL/L/min) and lowest for TCPC (1146 ± 386 mL/L/min), with a trend toward lower common atrial and pulmonary artery pressures for SVC Glenn. CONCLUSIONS: SVC bidirectional Glenn circulation might allow optimal augmentation of the CI and oxygen delivery in a failing single ventricle using a conventional pediatric ventricular assist device. The results from our model also suggest that the Fontan circulation itself can be supported with systemic ventricular assistance of the single ventricle.

Growth of diminutive central pulmonary arteries after right ventricle to pulmonary artery homograft implantation.

BACKGROUND: The management of tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collateral arteries is controversial because of the wide variability of pulmonary artery (PA) and major aortopulmonary collateral arteries morphology. Several different staged strategies have been used to promote growth of diminutive PA branches. We have preferred a right ventricular (RV)-PA homograft for symmetrical growth of the central PA branches. In this study we evaluated the success of this strategy. METHODS: Between 2006 and 2012, 23 patients with pulmonary atresia and diminutive PAs underwent RV-PA homograft implantation. Median age was 2 months (range, 4 days to 18 months), and median body weight was 5.1 kg (range, 1.7 to 8.5 kg). The type of homograft was aortic in 8, pulmonary in 6, and femoral vein in 9. The mean diameter of the homograft was 10.5 mm (range, 6 to 16 mm). All procedures were performed on cardiopulmonary bypass. The PA diameter was measured at the time of the operation and subsequent catheterization. RESULTS: The median size of the branch PA was 2.1 mm. In the 18 patients who had serial assessment of PA size, the right PA increased by 307% ± 184%, the left PA increased by 283% ± 139%, and the Nakata index increased from 28.8 ± 20.1 mm(2)/m(2) to 253 ± 96 mm(2)/m(2) during a median period of 347 days (range, 44 to 1,520 days). The PA growth ratio (PA growth in mm/mo) was similar between the right PA (0.42 ± 0.46 mm/mo) and the left PA (0.43 ± 0.47 mm/mo). There was no acute conduit failure. Seventeen patients required 28 percutaneous interventions for embolization of an aortopulmonary collateral or stenosis of the conduit or PA. There were no hospital deaths. Three patients died late after other procedures during a mean follow-up of 44.7 months. Twenty patients (87%) have undergone complete repair to date. CONCLUSIONS: RV-PA homograft implantation can be performed in neonates and infants with minimal risk of acute occlusion. The RV-PA homograft promotes rapid and balanced growth of central pulmonary arteries leading to complete repair in most patients.

Radiofrequency catheter ablation of intractable ventricular tachycardia in an infant following arterial switch operation.

A full-term male neonate presented with cyanosis upon delivery and was subsequently diagnosed with d-transposition of the great arteries, ventricular septal defect, and restrictive atrial septal defect. Following initiation of intravenous prostaglandins and balloon atrial septostomy, an arterial switch operation was performed on day 3 of life. The postoperative course was complicated by intractable ventricular tachycardia that was refractory to lidocaine, amiodarone, esmolol, fosphenytoin, and mexiletine drug therapy. Ventricular tachycardia was suppressed with overdrive atrial pacing but recurred upon discontinuation. Seven weeks postoperatively, radiofrequency catheter ablation was performed due to hemodynamically compromising persistent ventricular tachycardia refractory to medical therapy. The ventricular tachycardia was localized to the inferior-lateral right ventricular outlet septum. The procedure was successful without complications or recurrence. Antiarrhythmics were discontinued after the ablation procedure. Seven days after the ablation, a different, slower fascicular rhythm was noted to compete with the infant's sinus rhythm. This was consistent with the preablation amiodarone having reached subtherapeutic levels given its very long half-life. The patient was restarted on oral beta blockers and amiodarone. The patient was subsequently discharged home in predominantly sinus rhythm with intermittent fascicular rhythm.

Nonpharmacologic control of postoperative supraventricular arrhythmias using AV nodal fat pad stimulation in a young animal open heart surgical model.

BACKGROUND: Supraventricular arrhythmias (junctional ectopic tachycardia [JET] and atrial tachyarrhythmias) frequently complicate recovery from open heart surgery in children and can be difficult to manage. Medical treatment of JET can result in significant morbidity. Our goal was to develop a nonpharmacological approach using autonomic stimulation of selective fat pad (FP) regions of the heart in a young canine model of open heart surgery to control 2 common postoperative supraventricular arrhythmias. METHODS AND RESULTS: Eight mongrel dogs, varying in age from 5 to 8 months and weighting 22±4 kg, underwent open heart surgery replicating a nontransannular approach to tetralogy of Fallot repair. Neural stimulation of the right inferior FP was used to control the ventricular response to supraventricular arrhythmias. Right inferior FP stimulation decreased baseline AV nodal conduction without altering sinus cycle length. AV node Wenckebach cycle length prolonged from 270±33 to 352±89 ms, P=0.02. Atrial fibrillation occurred in 7 animals, simulating a rapid atrial tachyarrhythmias. FP stimulation slowed the ventricular response rate from 166±58 to 63±29 beats per minute, P<0.001. Postoperative JET occurred in 7 dogs. FP stimulation slowed the ventricular rate during postoperative JET from 148±31 to 106±32 beats per minute, P<0.001, and restored sinus rhythm in 7/7 dogs. CONCLUSIONS: Right inferior FP stimulation had a selective effect on the AV node, and slowed the ventricular rate during postoperative JET and atrial tachyarrhythmias in our young canine open heart surgery model. FP stimulation may be a useful new technique for managing children with JET and atrial tachyarrhythmias.

Newly created animal model of human postoperative junctional ectopic tachycardia.

OBJECTIVE: Junctional ectopic tachycardia complicates the postoperative recovery from open heart surgery in children. The reported risk factors include younger age, prolonged cardiopulmonary bypass times, and administration of inotropic agents. Junctional ectopic tachycardia occurs early after open heart surgery, in the setting of relative postoperative sinus node dysfunction, and exhibits QRS morphology consistent with an origin from the atrioventricular node or proximal conduction system. Our goal was to develop a reproducible animal model for postoperative junctional ectopic tachycardia. METHODS: Eleven pigs, aged 2 to 4 months, underwent open heart surgery after induction of general anesthesia. Electrodes were sewn to the left atrium and right ventricle. RESULTS: Sinus node dysfunction was created using clamp crushing without or with radiofrequency ablation (successful in 1 of 5 pigs) or sinus node removal (successful in 4 of 4). After prolonged cardiopulmonary bypass (>120 minutes) alone and with isoproterenol infusion, no spontaneous junctional ectopic tachycardia developed. Junctional ectopic tachycardia or fascicular tachycardia could be initiated after either slow atrioventricular nodal pathway ablation and/or digoxin administration. Junctional ectopic tachycardia occurred in 8 of 9 pigs (mean ventricular rate, 171 ± 32 bpm), and fascicular tachycardia occurred in 9 of 9 pigs (mean ventricular rate, 187 ± 39 bpm). His and right bundle recordings confirmed the conduction system origin. CONCLUSIONS: Experimental junctional ectopic tachycardia or fascicular tachycardia can occur in the intraoperative setting of sinus node dysfunction, prolonged cardiopulmonary bypass, and enhanced conduction system automaticity. Conduction system automaticity occurred after either physical injury (ablation or tricuspid valve stretch) or measures to augment the transient inward current of the conduction system (isoproterenol and digoxin). This animal model can serve as the basis to assess new treatments of postoperative junctional ectopic tachycardia.

Left thoracoscopic sympathectomy used as primary therapy for a young child with intractable long QT syndrome.

A 3-year-old boy with familial long QT syndrome type 2 presented with recurrent syncope despite adequate beta-blocker therapy. Two family members had experienced sudden cardiac arrest, and one other relative had experienced sudden cardiac death. Given the high risk for ventricular arrhythmia/syncope, the decision was made to perform primary cardiac denervation therapy through a minimally invasive approach without concomitant automatic cardioverter-defibrillator implantation. Using video-assisted thoracoscopic surgery, the left-sided sympathetic ganglia from T2-T5 were identified, and dissection along the sympathetic chain with transection of the corresponding rami along T2-T5 in addition to the lower half of the stellate ganglion was performed. The chest tube was removed on day 1 after surgery, and the patient was discharged on postoperative day 4. During 14 months of follow-up evaluation, no intervening episodes of ventricular arrhythmia or syncope and no symptoms of Horner's syndrome were noted.

Intra/extracardiac fenestrated modification leads to lower incidence of arrhythmias after the Fontan operation.

OBJECTIVE: The study objective was to compare the incidence of short- and intermediate-term arrhythmias among 3 different surgical modifications of the Fontan procedure. METHODS: We performed a retrospective review of all patients who underwent the Fontan operation at a single institution between January 2004 and May 2010 for preoperative, perioperative, and follow-up variables. Three surgical modifications were studied: intra/extracardiac conduit with limited atriotomy, standard extracardiac conduit, and lateral tunnel. Rhythm was classified as normal or abnormal. A rhythm dysfunction grading was devised and used to identify worsening of rhythm for patients with abnormal rhythm preoperatively. Multivariable logistic regression was used to determine predictors of abnormal rhythm. To eliminate confounding effects of transient immediate postoperative arrhythmias, data were analyzed for abnormal rhythm within the first 2 weeks and for more than 2 weeks after surgery. RESULTS: Of the 134 patients (n = 50 with intra/extracardiac conduit with limited atriotomy, n = 19 with standard extracardiac conduit, n = 65 with lateral tunnel) (median follow-up, 36 months; interquartile range, 22-50 months; 2 operative deaths and 6 late deaths), rhythm data for more than 2 weeks postoperatively were available in 88 (40 with lateral tunnel, 14 with standard extracardiac conduit, 34 with intra/extracardiac conduit with limited atriotomy). These patients constituted the study groups. Patients in the lateral tunnel group were relatively younger at the time of the Fontan operation (P < .001) and had a longer follow-up (P < .001). Multivariable logistic regression confirmed that greater than moderate atrioventricular valve regurgitation was the only independent predictor of abnormal rhythm during the first 2 postoperative weeks. Older age at Fontan (odds ratio, 1.20; 95% confidence interval, 1.05-1.38; P = .012) and higher preoperative mean pulmonary artery pressure (odds ratio, 1.2; 95% confidence interval, 1.03-1.44; P = .026) were predictors of abnormal rhythm more than 2 weeks postoperatively. Intra/extracardiac conduit with limited atriotomy Fontan modification was associated with a significantly lower incidence of abnormal rhythm after 2 weeks postoperatively compared with lateral tunnel modification (odds ratio, 0.28; 95% confidence interval, 0.10-0.84; P = .015). CONCLUSIONS: Intra/extracardiac conduit with limited atriotomy Fontan modification has a significantly lower risk of abnormal rhythm postoperatively in the short and intermediate term when compared with the lateral tunnel.

Pulmonary overcirculation following left atrial decompression in hypoplastic left heart syndrome with intact/restrictive atrial septum.

Patients with hypoplastic left heart syndrome (HLHS) with intact or severely restrictive atrial septum have slow resolution of their elevated pulmonary vascular resistance after left atrial decompression. We report two neonates who required urgent surgical intervention because of unusually rapid fall in their pulmonary vascular resistance following left atrial decompression leading to pulmonary overcirculation and severe congestive heart failure. HLHS with intact or severely restrictive atrial septum is a predictor of poor outcome. The need for left atrial decompression can be predicted by well defined fetal echocardiographic indicators. However evolution of pulmonary resistance can be difficult to predict. In some patients decompression of the left atrium can lead to early excessive pulmonary blood flow and congestive heart failure requiring urgent intervention. Here, we report two cases of HLHS with highly restrictive atrial septum that after atrial septostomy had an accelerated transition requiring urgent intervention. Because of retrospective nature of the study, Children's National Medical Center approved waiver of informed consent.

Effects of glutaraldehyde concentration, pretreatment time, and type of tissue (porcine versus bovine) on postimplantation calcification.

OBJECTIVE: Our objective was to evaluate the effects of glutaraldehyde (GA) concentration, time of pretreatment, and type of tissue (porcine vs bovine) on quantitative and qualitative postimplant calcification of tissues. METHODS: Freshly obtained porcine and bovine pericardial tissues were each treated with increasing concentrations of GA (controls, 0.3125%, 0.625%, and 1.2%) for a fixed time (15 minutes) or increasing exposure times (5, 10, 20, and 30 minutes) at a fixed concentration of GA (0.625%). Pretreated tissues were subcutaneously implanted in 10-week-old Sprague-Dawley rats for 45 days before explantation. Quantitative calcium analysis was performed by flame atomic spectrophotometry. Histologic examination of tissue samples with hematoxylin and eosin and von Kossa staining was performed for cellular and inflammatory response, autolysis, and calcification. RESULTS: Two-way analysis of variance indicated significantly greater calcium levels at 1.2% compared with each lower concentration for both porcine and bovine samples (P < .01). Significantly lower calcium levels were detected with increased exposure time in porcine samples (F = 6.97; P < .001); however, no significant differences in calcium levels were observed between different exposure times for bovine samples (F = 1.46; P = .23). Histologic evidence of inflammatory response with infiltration with mononuclear cells, fibroblasts, and histiocytes was seen in all grafts; however, it varied from mild to severe without any pattern. There were no differences in degree or pattern of inflammatory response according to GA concentration or time of exposure. Estimation of amount of calcification by histologic examination correlated with the quantitative assay. CONCLUSIONS: Increasing GA concentration leads to greater calcification with a sharp rise in calcium levels above a concentration of 0.625%, in both bovine and porcine pericardial tissues. At a concentration of 0.625%, increasing pretreatment time is inversely related to tissue calcification for porcine pericardium but not for bovine pericardium. Differences in the tissue composition in terms of cellular content and composition of the extracellular matrix could account for the observed findings.

Complete atrioventricular canal with guarded primum septal defect.

Common atrioventricular canal (CAVC) is a common congenital heart lesion resulting from a defect in development of the endocardial cushions during early embryogenesis. Depending on the type of defect, CAVC can encompass a spectrum of lesions ranging from partial atrioventricular (AV) canal to complete AV canal. We describe a case of CAVC with unique anatomy in a 4-month-old male infant with Down syndrome.

Reversal of mitochondrial defects before ischemia protects the aged heart.

Myocardial injury is increased in the aged heart during ischemia and reperfusion. Aging decreases oxidative metabolism in interfibrillar mitochondria (IFM) located between the myofibrils. We asked whether reversal of aging defects in IFM before ischemia would decrease injury in the aged heart following ischemia and reperfusion. Treatment with acetylcarnitine (AcCN) increases the activity of cytochrome oxidase in the aged heart. Aged (24 months) and adult (6 months) Fischer 344 rats were treated with AcCN (300 mg/kg i.p. 3 h before excision of the heart) or served as controls. AcCN restored oxidative phosphorylation and the activity of complexes III and IV in IFM from aged hearts to rates present in adults. Isolated hearts underwent 25 min global ischemia and 30 min reperfusion without additional treatment. Contractile recovery during reperfusion improved in hearts from AcCN-treated aged rats compared to aged controls and were similar to adults in recovery. AcCN-treated aged hearts sustained less damage, indicated by decreased lactate dehydrogenase (LDH) release during reperfusion. AcCN treatment did not alter functional recovery or LDH release in adults. Restoration of mitochondrial function in the aged heart before ischemia was accompanied by enhanced contractile recovery and decreased tissue injury following ischemia and reperfusion.