Surgical Closure of Patent Ductus Arteriosus in Premature Neonates Weighing Less Than 1,000 grams: Contemporary Outcomes

Objective:

The safety of surgical closure of patent ductus arteriosus (PDA) in very low birth weight premature neonates has been questioned because of associated morbidities. However, these studies are vulnerable to significant bias as surgical ligation has historically been utilized as “rescue” therapy. The objective of this study was to review our institutions’ outcomes of surgical PDA ligation.

Methods:

All neonates with operative weight of ≤1.00 kg undergoing surgical PDA ligation from 2003 to 2015 were analyzed. Records were queried to identify surgical complications, perioperative morbidity, and mortality. Outcomes included pre- and postoperative ventilator requirements, pre- and postoperative inotropic support, acute kidney injury, surgical complications, and 30-day mortality.

Results:

One hundred sixty-six preterm neonates underwent surgical ligation. One hundred twenty-one (70.3%) had failed indomethacin closure. One hundred sixty-four (98.8%) patients required mechanical ventilation prior to surgery. At 17 postoperative days, freedom from the ventilator reached 50%. Of 109 (66.4%) patients requiring prolonged preoperative inotropic support, 59 (54.1%) were liberated from inotropes by postoperative day 1. Surgical morbidity was encountered in four neonates (2.4%): two (1.2%) patients had a postoperative pneumothorax requiring tube thoracostomy, one (0.6%) patient had a recurrent laryngeal nerve injury, and one (0.6%) patient had significant intraoperative bleeding. The 30-day all-cause mortality was 1.8% (n = 3); no deaths occurred intraoperatively.

Conclusion:

In this retrospective investigation, surgical PDA closure was associated with low 30-day mortality and minimal morbidity and resulted in rapid discontinuation of inotropic support and weaning from mechanical ventilation. Given the safety of this intervention, surgical PDA ligation merits consideration in the management strategy of the preterm neonate with a PDA.

Circumflex aorta with double aortic arch in an infant

Circumflex aorta and double aortic arch are two forms of rare vascular rings. We present a case of an infant who was diagnosed with circumflex aorta and double aortic arch, and describe the surgical management of this rare anomaly.

Acute humoral rejection in an infant without risk factors after heart transplantation

Graft rejection is the most common factor that limits graft survival after transplantation. During infancy, the humoral immune system is partially suppressed and humoral rejection of a cardiac allograft has not been reported in the absence of risk factors such as prior transplantation, blood transfusions, ventricular assist devices, and elevation of panel reactive antibodies. We present a case of an infant with dilated cardiomyopathy who developed multiple episodes of acute humoral rejection after heart transplantation in the absence of risk factors.

Pediatric Mechanical Circulatory Support

Over the past two decades clinicians and researchers have sought to bring mechanical circulatory support (MCS) to pediatric patients with heart failure. ECMO, IABPs, and VADs have all been used in infants and children as a bridge to myocardial recovery or as a bridge to transplant. However, until recently, a commitment by industry, government, and researchers towards the development of pediatric MCS has not been present, especially in the United States. Advancements in adult VAD design to smaller, quieter, and fully implantable pumps capable of complete outpatient support have sparked curiosity in the application of this technology to children. Also, the increasing success of palliating congenital heart disease is creating an ever-growing cohort of children and adolescents with heart failure. These changing demographics and technological advances have caused a refocus of attention. This is most clearly demonstrated by the international use of several established MCS pediatric and neonatal systems, by the FDA's increasing proclivity to allow the use of international pediatric VADs in the USA, and by the recent National Heart, Lung, and Blood Institute funding of several institutions to develop pediatric VADs. This review describes the different aspects of pediatric MCS including indications, the features of the various VADs, and their current application in children worldwide.

Whole exome sequencing in 342 congenital cardiac left sided lesion cases reveals extensive genetic heterogeneity and complex inheritance patterns

BACKGROUND

Left-sided lesions (LSLs) account for an important fraction of severe congenital cardiovascular malformations (CVMs). The genetic contributions to LSLs are complex, and the mutations that cause these malformations span several diverse biological signaling pathways: TGFB, NOTCH, SHH, and more. Here, we use whole exome sequence data generated in 342 LSL cases to identify likely damaging variants in putative candidate CVM genes.

METHODS

Using a series of bioinformatics filters, we focused on genes harboring population-rare, putative loss-of-function (LOF), and predicted damaging variants in 1760 CVM candidate genes constructed a priori from the literature and model organism databases. Gene variants that were not observed in a comparably sequenced control dataset of 5492 samples without severe CVM were then subjected to targeted validation in cases and parents. Whole exome sequencing data from 4593 individuals referred for clinical sequencing were used to bolster evidence for the role of candidate genes in CVMs and LSLs.

RESULTS

Our analyses revealed 28 candidate variants in 27 genes, including 17 genes not previously associated with a human CVM disorder, and revealed diverse patterns of inheritance among LOF carriers, including 9 confirmed de novo variants in both novel and newly described human CVM candidate genes (ACVR1, JARID2, NR2F2, PLRG1, SMURF1) as well as established syndromic CVM genes (KMT2D, NF1, TBX20, ZEB2). We also identified two genes (DNAH5, OFD1) with evidence of recessive and hemizygous inheritance patterns, respectively. Within our clinical cohort, we also observed heterozygous LOF variants in JARID2 and SMAD1 in individuals with cardiac phenotypes, and collectively, carriers of LOF variants in our candidate genes had a four times higher odds of having CVM (odds ratio = 4.0, 95% confidence interval 2.5-6.5).

CONCLUSIONS

Our analytical strategy highlights the utility of bioinformatic resources, including human disease records and model organism phenotyping, in novel gene discovery for rare human disease. The results underscore the extensive genetic heterogeneity underlying non-syndromic LSLs, and posit potential novel candidate genes and complex modes of inheritance in this important group of birth defects.

Aborted Sudden Cardiac Death After Unroofing of Anomalous Left Coronary Artery

We describe a patient with anomalous left coronary artery with a short intramural course and a previously unrecognized myocardial bridge who presented with a recurrent episode of aborted sudden cardiac death. Intravascular ultrasound and fractional flow reserve showed significant compression at the left coronary artery ostium by the intercoronary pillar and at the myocardial bridge. Intravascular ultrasound and fractional flow reserve were normal after coronary translocation and unroofing of the myocardial bridge. All potential anatomic culprits should be addressed when operating on patients with anomalous coronaries.

Outcomes of surgical intervention for anomalous aortic origin of a coronary artery: A large contemporary prospective cohort study

OBJECTIVE

The purpose of this study was to prospectively analyze the outcomes of patients with anomalous aortic origin of a coronary artery undergoing surgical intervention according to a standardized management algorithm.

METHODS

All patients aged 2 to 18 years undergoing surgical intervention for anomalous aortic origin of a coronary artery between December 2012 and April 2017 were prospectively included. Patients underwent stress nuclear perfusion imaging, stress cardiac magnetic resonance imaging, and retrospectively electrocardiogram-gated computed tomography angiography preoperatively. Patients were cleared for exercise at 3 months postoperatively if asymptomatic and repeat stress nuclear perfusion imaging, stress cardiac magnetic resonance imaging, and computed tomography angiography showed normal results.

RESULTS

A total of 44 patients, with a median age of 14 years (8-18 years), underwent surgical intervention: 9 (20%) for the anomalous left coronary artery and 35 (80%) for the anomalous right coronary artery. Surgical procedures included unroofing in 35 patients (80%), translocation in 7 patients (16%), ostioplasty in 1 patient (2%), and side-side-anastomosis in 1 patient (2%). One patient who presented with aborted sudden cardiac death from an anomalous left coronary and underwent unroofing presented 1 year later with a recurrent episode and was found to have an unrecognized myocardial bridge and persistent compression of the coronary requiring reintervention. At last follow-up, 40 patients (91%) are asymptomatic and 4 patients have nonspecific chest pain; 42 patients (95%) have returned to full activity, and 2 patients are awaiting clearance.

CONCLUSIONS

Surgical treatment for anomalous aortic origin of a coronary artery is safe and should aim to associate the coronary ostium with the correct sinus, away from the intercoronary pillar. After surgery, the majority of patients are cleared for exercise and remain asymptomatic. Longer follow-up is needed to assess the true efficacy of surgery in the prevention of sudden cardiac death.

The Neonatal Arterial Switch Operation: Technical Pearls

The neonatal arterial switch operation has become the standard of care for transposition of the great arteries, including transposition with intact ventricular septum, transposition with ventricular septal defect with or without aortic arch hypoplasia, and double outlet right ventricle with subpulmonary ventricular septal defect (Taussig-Bing anomaly). While technically demanding, the operation is enormously gratifying and exciting for the congenital heart surgeon. In the current era, outcomes and expectations for the neonatal arterial switch operation are extremely high with many centers, including our own, reporting 30-day or hospital survivorship approaching 100%. Long-term results are also outstanding, although these patients do require lifelong follow-up and have the potential for need of remedial surgical intervention.

Static cerebrovascular pressure autoregulation remains intact during deep hypothermia

BACKGROUND

Clinical studies measuring cerebral blood flow in infants during deep hypothermia have demonstrated diminished cerebrovascular pressure autoregulation. The coexistence of hypotension in these cohorts confounds the conclusion that deep hypothermia impairs cerebrovascular pressure autoregulation.

AIM

We sought to compare the lower limit of autoregulation and the static rate of autoregulation between normothermic and hypothermic piglets.

METHODS

Twenty anesthetized neonatal piglets (5-7 days old; 10 normothermic and 10 hypothermic to 20°C) had continuous measurements of cortical red cell flux using laser Doppler flowmetry, while hemorrhagic hypotension was induced without cardiopulmonary bypass. Lower limit of autoregulation was determined for each subject using piecewise regression and SRoR was determined above and below each lower limit of autoregulation as (%change cerebrovascular resistance/%change cerebral perfusion pressure).

RESULTS

The estimated difference in lower limit of autoregulation was 1.4 mm Hg (lower in the hypothermic piglets; 95% C.I. -10 to 14 mm Hg; P=0.6). The median lower limit of autoregulation in the normothermic group was 39 mm Hg [IQR 38-51] vs 35 mm Hg [31-50] in the hypothermic group. Intact steady-state pressure autoregulation was defined as static rate of autoregulation >0.5 and was demonstrated in all normothermic subjects (static rate of autoregulation=0.72 [0.65-0.87]) and in 9/10 of the hypothermic subjects (static rate of autoregulation=0.65 [0.52-0.87]). This difference in static rate of autoregulation of 0.06 (95% C.I. -0.3 to 0.1) was not significant (P=0.4).

CONCLUSION

Intact steady-state cerebrovascular pressure autoregulation is demonstrated in a swine model of profound hypothermia. Lower limit of autoregulation and static rate of autoregulation were similar in hypothermic and normothermic subjects.

Intra-Aortic Missile After Gunshot Wound to Chest: An Interesting Case of Traumatic Cardiac Injury

Missile embolus to the heart, although uncommon, is one of the most challenging scenarios in trauma. We describe a 36-year-old man who presented with a gunshot wound to the left chest and a chest x-ray revealing a foreign body in the mediastinum. A median sternotomy was performed and an injury to the left ventricle was identified. After intraoperative echocardiography and fluoroscopy confirmed a foreign body in the aortic root, cardiopulmonary bypass was implemented. A bullet was retrieved from the noncoronary sinus of the aortic valve. Injuries to the anterior leaflet of the mitral valve and left ventricle were repaired.

The Ontogeny of Cerebrovascular Critical Closing Pressure

Premature infants are at risk of vascular neurological insults. Hypotension and hypertension are considered injurious, but neither condition is defined with consensus. Critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow ceases. CrCP may serve to define subject-specific low or high ABP. Our objective was to quantify CrCP as a function of gestational age (GA). One hundred eighty-six premature infants with a GA range of 23-33 weeks, were monitored with umbilical artery catheters and transcranial Doppler insonation of middle cerebral artery flow velocity (FV) for 1-h sessions over the first week of life. CrCP was calculated using an impedance model derivation with Doppler-based estimations of cerebrovascular resistance and compliance. CrCP increased significantly with GA (r = 0.47; slope = 1.4 mmHg/week gestation), an association that persisted with multivariate analysis (p < 0.001). Higher diastolic ABP and higher GA were associated with increased CrCP (p <0.001 for both). CrCP increases significantly at the end of the second and beginning of the third trimester. The low CrCP observed in premature infants may explain their ability to tolerate low ABP without global cerebral infarct or hemorrhage.

The Diastolic Closing Margin Is Associated with Intraventricular Hemorrhage in Premature Infants

Premature infants are at an increased risk of intraventricular hemorrhage (IVH). The roles of hypotension and hyperemia are still debated. Critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. When diastolic ABP is equal to CrCP, CBF occurs only during systole. The difference between diastolic ABP and CrCP is the diastolic closing margin (DCM). We hypothesized that a low DCM was associated with IVH. One hundred eighty-six premature infants, with a gestational age (GA) range of 23-33 weeks, were monitored with umbilical artery catheters and transcranial Doppler insonation of middle cerebral artery flow velocity for 1-h sessions over the first week of life. CrCP was calculated linearly and using an impedance model. A multivariate generalized linear regression model was used to determine associations with severe IVH (grades 3-4). An elevated DCM by either method was associated with IVH (p < 0.0001 for the linear method; p < 0.001 for the impedance model). Lower 5-min Apgar scores, elevated mean CBF velocity, and lower mean ABP were also associated with IVH (p < 0.0001). Elevated DCM, not low DCM, was associated with severe IVH in this cohort.