The impact of surgical repair on left ventricular outflow tract in atrioventricular septal defect with common atrioventricular valve orifice

Objective

Although a narrow left ventricular outflow tract in atrioventricular septal defect is related to its intrinsic morphology, the contribution from the repair technique remains to be quantified.

Methods

A total of 108 patients with an atrioventricular septal defect with a common atrioventricular valve orifice were divided into 2 groups: 2-patch (N = 67) and modified 1-patch (N = 41) repair. The left ventricular outflow tract morphometric was analyzed by quantifying the degree of disproportion between subaortic and aortic annular dimensions (disproportionate morphometrics ratio was defined as ≤ 0.9). Z-scores (median, interquartile range) were further analyzed in a subset of 80 patients with immediate preoperative and postoperative echocardiography. A total of 44 subjects with ventricular septal defects served as controls.

Results

Before repair, 13 patients (12%) with an atrioventricular septal defect had disproportionate morphometrics (vs 6 [14%] ventricular septal defect P = .79), but the subaortic Z-score (-0.53, -1.07 to 0.06) was lower than the ventricular septal defect (0.07, -0.57 to 1.17; P < .001). After repair, both 2-patch (8 [12%] preoperatively vs 25 [37%] postoperatively; P = .001) and modified 1-patch (5 [12%] vs 21 [51%], P < .001) procedures showed a greater degree of disproportionate morphometrics. Both 2-patch (postoperatively -0.73, -1.56 to 0.08 vs preoperatively -0.43, -0.98 to 0.28; P = .011) and modified 1-patch (-1.42, -2.63 to -0.78 vs -0.70, -1.18 to -0.25; P = .001) procedures also demonstrated lower subaortic Z-scores postrepair. The postrepair subaortic Z-scores were lower in the modified 1-patch group (-1.42 [-2.63 to -0.78]) compared with the 2-patch group (-0.73 [-1.56 to 0.08]; P = .004). Low postrepair subaortic Z-scores (<-2) were observed in 12 patients (41%) in the modified 1-patch group and 6 patients (12%) in the 2-patch group (P = .004).

Conclusions

Surgical correction resulted in greater disproportionate morphometrics seen immediately postrepair. The impact on the left ventricular outflow tract was observed in all repair techniques, with a greater burden seen after modified 1-patch repair.

Video Abstract

This morphometric study in AVSD with common atrio-ventricular valve orifice confirmed further derangements of LV outflow tract morphometrics immediately after surgical repair.

The role of abnormal subaortic morphometry as a substrate for left ventricular outflow tract obstruction following atrioventricular septal defect repair

OBJECTIVES

Although left ventricular outflow tract (LVOT) obstruction is a recognized risk after atrioventricular (AV) septal defect (AVSD) repair, quantitative assessments to define the substrate of the obstruction are lacking.

METHODS

Morphometric analyses were based on measurements from early 2-dimensional echocardiographic scans (within 3 months postoperatively) for 117 patients (82 CAVVO = common AV valve; 35 SAVVO = separate AV valve orifices), which were compared to 50 age/weight matched controls (atrial septal defect/ventricular septal defect). Late echocardiographic analyses were performed in 57 patients with AVSD (follow-up range, 1.2-10.7 years).

RESULTS

Adequate z scores (above -2.5) were observed in 109 (93%) patients with AVSD at the aortic annulus and in 89 (76%) with AVSD in the subaortic area. Compared to the control group, patients with AVSD had lower median z scores at the aortic annulus (-0.64 vs 0.60; P < 0.001) and the subaortic areas (-1.48 vs 0.59; P < 0.001), disproportionate subaortic/aortic annulus ratio <1.00 (67% vs 22%; P < 0.001), narrower annuloaortic-septal angle (94.0 vs 104.0; P < 0.001) and annuloaortic left AV valve angle (78.0 vs 90.0; P < 0.001). Compared to patients with CAVVO, those with SAVVO had narrower annuloaortic-septal angles (P = 0.022) that persisted at late analysis, with lower subaortic/aortic annular ratios (P = 0.039). In patients with CAVVO, lower early postoperative subaortic z scores were found following modified single-patch repairs (median -2.12 vs -1.02 in two-patch repairs; P = 0.004). A total of 6/117 (5%) patients (4 CAVVO, 5% and 2 SAVVO, 6%) required reoperations for LVOT obstruction (mean 6.9 years postoperatively), with no difference in morphology or types of operations.

CONCLUSIONS

Despite having adequate z scores, patients with AVSD demonstrated abnormal LVOT morphometrics early postoperatively. Besides intrinsic morphology, repair techniques may have an impact on postoperative LVOT morphometrics and requires further evaluation.

Remote ALCAPA Repair-Total Arterial Reconstruction Using Free Aortic Graft Technique

A late presenting anomalous left coronary artery from pulmonary artery (ALCAPA) with remote origin may be associated with several technical caveats due to distance for coronary transfer and inadequate autologous tissues for reconstruction. A technique using full circumferential aortic wall as a free graft that is sutured as a posterior hood on an anterior pulmonary arterial flap is used to achieve reconstruction of a neo-left coronary that is tension free, with laminar flow and without the use of any prosthetic material. The technique with potential modifications described could potentially be applied to any variant of ALCAPA to achieve total arterial reconstruction to yield an optimal long-term outcome.

Superior Vena Cava Inflow Following Repair for Anomalous Right Pulmonary Venous Drainage in Children

Risk of superior vena cava (SVC) obstruction following repair of anomalous right upper pulmonary veins in children is unclear. The incidence and outcome of subclinical obstruction remained unknown. Retrospective single institutional study (07/1993-02/2017) in a pediatric population (N = 42, median age 3.9-year, range 0.1-15.3 years). 33 (79%) children had repair without SVC translocation ("non-Warden") and 9 (21%) had Warden-type surgery. Echocardiographic SVC obstruction was defined as (I) turbulent flow across SVC and (II) continuous flow pattern without return to baseline velocity (0 m/s); severe obstruction was defined as loss of distinct biphasic profile ± mean gradient ≥ 5 mmHg. 3 (7%) patients required intra-operative revision due to obstruction (non-Warden: 1, Warden: 2). After discharge, 2 (5%) patients required reintervention (3 and 6-month post-op) for severe symptomatic obstruction (non-Warden: 1, Warden-type: 1). Both patients responded to balloon angioplasty with symptomatic resolution (one required repeat catheter reintervention). 10 (24%) patients had subclinical echocardiographic obstruction (2, 22% Warden vs. 8, 24% non-Warden; p = 1.0; 8 of 10 patients had mild gradient), which resolved and remained well without reintervention. At follow-up (mean 7.2-year, range 0-23 years), all patients were alive. Freedom from SVC reintervention at 10 and 20-year is 95% (97% at 10, 20-year in non-Warden and 89% at 5, 8-year in Warden-type group; log-rank p = 0.34). Surgical repair for anomalous right upper pulmonary veins is associated with risk of SVC obstruction in children. The need for reintervention for severe obstruction is rare at late follow-up. Patients with subclinical obstruction remain asymptomatic and demonstrate echocardiographic improvement.

Surgical Approach for Hypoplastic Mirror Circumflex Aortic Arch

Surgical approach for the mirror-form of circumflex aortic arch with a long-segment hypoplasia is described. Instead of "uncrossing" the arch, posterior aortic translocation of the aorta is required for the mirror-form. These surgical strategies addressed all the associated patho-mechanisms: (1) relief of vascular ring, (2) removal of posterior arch compression on the trachea, and (3) correction of any arch obstruction. Posterior tracheobronchopexy was further required to address severe underlying tracheobronchomalacia.

Extracorporeal membrane oxygenation in pediatric cardiac surgery: A retrospective review of trends and outcomes in Scotland

Introduction:

Around 3.2%–8.4% of patients receive venoarterial (VA) extracorporeal membrane oxygenation (ECMO) support after pediatric cardiac surgery. The desired outcome is “bridge-to-recovery” in most cases. There is no universally agreed protocol, and given the associated costs and complications rates, the decisions as of when and when not to institute VA ECMO are largely empirical.

Methods:

A retrospective review of the ECMO database at the Scottish Pediatric Cardiac Services (SPCS) was undertaken. Inclusion criterion encompassed all children (<16 years of age) who were supported with VA ECMO following cardiac surgery between January 2011 and October 2016. The timing of ECMO support was divided into three distinct phases: “endofcase” or intheatre ECMO for patients unable to effectively wean from cardiopulmonary bypass (CPB), ECMO for cardiopulmonary resuscitation (“ECPR”), and Intensive Care Unit ECMO for “failing maximal medial therapy” following cardiac surgery. The patients were analyzed to identify survival rates, adverse prognostic indicators, and complication rates.

Results:

We identified 66 patients who met the inclusion criterion. 30day survival rate was 45% and survival rate to hospital discharge was 44% (the difference represents one patient). On followup (median: 960 days, range: 42–2010 days), all survivors to hospital discharge were alive at review date. “End-of-case” ECMO showed a trend toward better survival of the three subcategories (“end of case,” ECPR, and ECMO for “failing maximal medical therapy” survival rates were 47%, 41%, and 37.5%, respectively, P = 0.807). The poorest survival rates were in the younger children (<6 months, P = 0.502), patients who had prolonged CPB (P = 0.314) and aortic crossclamp times (P = 0.146), and longer duration of ECMO (>10 days, P = 0.177).

Conclusions:

Allcomers VA ECMO following pediatric cardiac surgery had survival to discharge rate of 44%. Elective “end-of-case” ECMO carries better survival rates and therefore ECMO instituted early maybe advantageous. Prolonged ECMO support has a direct correlation with mortality.

Restrictive Cardiomyopathy or Constrictive Pericarditis: An Unresolved Conundrum

Cardiomyopathy may have a variety of causes and may lead to significant morbidity. Often, there is no "perfect" treatment. New investigative techniques may add insight but retain the possibility of uncertainty. The distinction between restrictive cardiomyopathy and pericardial constriction may be challenging, particularly when considering the incidence of these entities. This distinction may significantly impact patient management and this is becoming increasingly important in the context of donor organ austerity. We present a case of a 17-year-old male to illustrate the overlap highlighting this debate and our subsequent management.

An Extended Role of Continuous Flow Device in Pediatric Mechanical Circulatory Support

BACKGROUND

Mechanical circulatory support in the pediatric population is currently limited to pulsatile ventricular assist devices (VAD). In recent years, the use of durable, newer generation, continuous flow devices have increased substantially among adults with end-stage heart failure. We examined the extended role of this device in the pediatric population (aged less than 18 years).

METHODS

Between 2010 and 2015, 12 patients (median age 7.1 years; range, 3.7 to 17.0; one third of patients were aged 5 years or less) received a HeartWare ventricular assist device (HVAD; HeartWare, Framingham, MA), 11 for cardiomyopathy and 1 for posttransplant rejection. Right VAD support (n = 5; 42%) was provided by a short-term device (Levitronix, Zurich, Switzerland).

RESULTS

Overall, 1 patient died (day 638), 8 patients (67%) underwent transplantation, 1 patient (8.3%) recovered, and 2 patients (17%) remain on HVAD. The mean length of support was 150 days (range, 16 to 638). Four patients (33.3%) were discharged home (all left VAD). In the left VAD group (n = 7), 3 patients subsequently received transplants (days 185, 201, and 234, respectively), 1 recovered (day 149), 1 died (day 638), 1 remained on HVAD (day 198), and 1 needed conversion to biventricular assist device (BIVAD [day 73]). In the BIVAD group (n = 5), right VAD was weaned in 3 (60%), all subsequently received transplants, and 2 remained on BIVAD support until transplant (days 16 and 17, respectively). One BIVAD patient required conversion to central cannulation for longer-term support. Four BIVAD patients (80%) were in Interagency Registry for Mechanically Assisted Circulatory Support level 1 before VAD compared with 2 (29%) in the left VAD group (p = not significant). The actuarial survival rate was 100% at 1 year with no neurologic events.

CONCLUSIONS

The third-generation, continuous flow device can provide durable support in the pediatric population. The selection strategy for patients who benefit most from the device continues to evolve. It is anticipated that a smaller design in the future will benefit an even wider pediatric population with heart failure.

Three-Sinus Repair of Elastin Arteriopathy Associated Supravalvar Pulmonary Stenosis With Bilateral Branch Pulmonary Artery Involvement

Elastin arteriopathy-associated supravalvar pulmonary stenosis is characterized by a thick intraluminal ringlike obstruction at the sinotubular junction of the pulmonary valve. Extension of disease into the branch pulmonary arteries is common. A three-sinus pulmonary trunk augmentation combined with bilateral branch pulmonary augmentation is presented. This approach normalizes the pulmonary trunk and allows optimal augmentation of the central pulmonary arteries.

Epicardial implantation of a transvenous implantable cardioverter-defibrillator system in Ebstein's malformation with tricuspid valve repair

In this case report, we describe the implant of a transvenous implantable cardioverter-defibrillator lead on the left ventricular epicardial surface of a young patient with Ebstein's anomaly, facilitating effective defibrillation and anti-tachycardia pacing. The difficulties of conventional placement in Ebstein's malformation as well as the technique and outcome of epicardial lead implantation of a transvenous defibrillator-pacer system are discussed. <Learning objective: This case report highlights the possible placement of a conventional transvenous defibrillator lead on alternative site such as epicardial surface as a solution in patients with Ebstein's anomaly undergoing open heart surgery. This case report also discusses technical challenges, which precluded the transvenous implantation route in a post-operative patient with Ebstein's anomaly. The advantages of epicardial versus subcutaneous system are also discussed.>.

Size dependent magnetic hyperthermia of octahedral Fe3O4 nanoparticles

Octahedral Fe₃O₄ nanoparticles show a wide size range for high SAR values to be used as an excellent thermal seed for magnetic hyperthermia cancer treatment.

Right ventricular outflow tract tumour: an unsuspected intracardiac ectopic thyroid mass

Ectopic thyroid is a rare embryogenic anomaly that occurs during its migration from foramen caecum to its pretracheal position. An intracardiac ectopic location is even rarer and found most commonly in the right ventricular outflow tract in sporadic reports. While surgery in symptomatic patients seems appropriate, resection of non-neoplastic ectopic tissue remains a clinical equipoise. Its occurrence is often unsuspected by clinicians, but its possibility should be considered due to its typical location in the right ventricular outflow tract. Unlike true neoplastic intracardiac tumour which mandates surgical resection, both surgical and non-surgical approach may be considered for an intracardiac ectopic thyroid mass.

Methylation of hMLH1 promoter correlates with the gene silencing with a region-specific manner in colorectal cancer

Microsatellite instability is present in over 80% of the hereditary non-polyposis colorectal carcinoma and about 15-20% of the sporadic cancer. Microsatellite instability is caused by the inactivation of the mismatch repair genes, such as primarily hMLH1, hMSH2. To study the mechanisms of the inactivation of mismatch repair genes in colorectal cancers, especially the region-specific methylation of hMLH1 promoter and its correlation with gene expression, we analysed microsatellite instability, expression and methylation of hMLH1 and loss of heterozygosity at hMLH1 locus in these samples. Microsatellite instability was present in 17 of 71 primary tumours of colorectal cancer, including 14 of 39 (36%) mucinous cancer and three of 32 (9%) non-mucinous cancer. Loss of hMLH1 and hMSH2 expression was detected in nine and three of 16 microsatellite instability tumours respectively. Methylation at CpG sites in a proximal region of hMLH1 promoter was detected in seven of nine tumours that showed no hMLH1 expression, while no methylation was present in normal mucosa and tumours which express hMLH1. However, methylation in the distal region was observed in all tissues including normal mucosa and hMLH1 expressing tumours. This observation indicates that methylation of hMLH1 promoter plays an important role in microsatellite instability with a region-specific manner in colorectal cancer. Loss of heterozygosity at hMLH1 locus was present in four of 17 cell lines and 16 of 54 tumours with normal hMLH1 status, while loss of heterozygosity was absent in all nine cell lines and nine tumours with abnormal hMLH1 status (mutation or loss of expression), showing loss of heterozygosity is not frequently involved in the inactivation of hMLH1 gene in sporadic colorectal cancer.

The Missing Link: Early Methane ("T") Dwarfs in the Sloan Digital Sky Survey

We report the discovery of three cool brown dwarfs that fall in the effective temperature gap between the latest L dwarfs currently known, with no methane absorption bands in the 1-2.5 µm range, and the previously known methane (T) dwarfs, whose spectra are dominated by methane and water. The newly discovered objects were detected as very red objects in the Sloan Digital Sky Survey imaging data and have JHK colors between the red L dwarfs and the blue Gl 229B-like T dwarfs. They show both CO and CH(4) absorption in their near-infrared spectra in addition to H(2)O, with weaker CH(4) absorption features in the H and K bands than those in all other methane dwarfs reported to date. Due to the presence of CH(4) in these bands, we propose that these objects are early T dwarfs. The three form part of the brown dwarf spectral sequence and fill in the large gap in the overall spectral sequence from the hottest main-sequence stars to the coolest methane dwarfs currently known.