After heart surgery in neonates and infants, both low-flow bypass and circulatory arrest perfusion strategies have comparable effects on the nonneurological postoperative course and hemodynamic profile.

Abstract-Pulmonary hypertension is associated with diverse cardiac, pulmonary, and systemic diseases in neonates, infants, and older children and contributes to significant morbidity and mortality. However, current approaches to caring for pediatric patients with pulmonary hypertension have been limited by the lack of consensus guidelines from experts in the field. In a joint effort from the American Heart Association and American Thoracic Society, a panel of experienced clinicians and clinician-scientists was assembled to review the current literature and to make recommendations on the diagnosis, evaluation, and treatment of pediatric pulmonary hypertension. This publication presents the results of extensive literature reviews, discussions, and formal scoring of recommendations for the care of children with pulmonary hypertension. Key Words: AHA Scientific Statements ◼ bronchopulmonary dysplasia ◼ congenital diaphragmatic hernia ◼ congenital heart disease ◼ genetics ◼ persistent pulmonary hypertension of the newborn ◼ sickle cell disease © 2015 by the American Heart Association, Inc., and the American Thoracic Society.Circulation is available at http://circ.ahajournals.org DOI: 10.1161/CIR.0000000000000329 †Deceased. The American Heart Association and the American Thoracic Society make every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.This document was approved by the American Heart Association Science Advisory and Coordinating Committee on May 12, 2015, the American Heart Association Executive Committee on July 22, 2015, and the American Thoracic Society on July 24, 2015.The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIR.0000000000000329/-/DC1. The American Heart Association requests that this document be cited as follows: Abman SH, Hansmann G, Archer SL, Ivy DD, Adatia I, Chung WK, Hanna BD, Rosenzweig EB, Raj JU, Cornfield D, Stenmark KR, Steinhorn R, Thébaud B, Fineman JR, Kuehne T, Feinstein JA, Friedberg MK, Earing M, Barst RJ, Keller RL, Kinsella JP, Mullen M, Deterding R, Kulik T, Mallory G, Humpl T, Wessel DL; on behalf of the American Heart Association Council on Cardiopulmonary, Critical Care, Perioperative and Resuscitation, Council on Clinical Cardiology, Council on Cardiovascular Disease in the Young, Council on Cardiovascular Radiology and Intervention, Council on Cardiovascular Surgery and Anesthesia, and the American Thoracic Society. Pediatric pulmonary hypertension: guidelines from the American Heart Association and American Thoracic Society. Circulation. 2015;132:2037-2099 Copies: This document is available on the World Wide Web site of the American Heart Associat...

technology advances to double performance every 18 months. The implicit hardware/software contract was that increased transistor count and power dissipation were OK as long as architects maintained the existing sequential programming model. This contract led to innovations that were inefficient in terms of transistors and power (such as multiple instruction issue, deep pipelines, out-of-order execution, speculative execution, and prefetching) but that increased performance while preserving the sequential programming model. The contract worked fine until we hit the power limit a chip is able to dissipate. Figure 1 reflects this abrupt change, plotting the projected microprocessor clock rates of the International Technology Roadmap for Semiconductors in 2005 and then again just two years later. 16 The 2005 prediction was that clock rates should have exceeded 10GHz in 2008, topping 15GHz in 2010. Note that Intel products are today far below even the conservative 2007 prediction. After crashing into the power wall, architects were forced to find a new paradigm to sustain ever-increasing performance. The industry decided the only viable option was to replace the single power-inefficient processor with many efficient processors on the same chip. The whole microprocessor industry thus declared that its future was in parallel computing, with increasing numbers of processors, or cores, each technology generation every two years. This style of chip was labeled a multicore microprocessor. Hence, the leap to multicore is not based on a breakthrough in programming or architecture and is actually a retreat from the more difficult task of building power-efficient, high-clock-rate, single-core chips. 5 Many startups have sold parallel computers over the years, but all failed, as programmers accustomed to continuous improvement in sequential performance saw little need to explore parallelism.

In heart surgery in infants, a strategy consisting predominantly of circulatory arrest is associated with greater central nervous system perturbation in the early postoperative period than a strategy consisting predominantly of low-flow cardiopulmonary bypass. Assessment of the effect of these findings on later outcomes awaits follow-up of this cohort.