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Single Ventricle Palliation: Stage One Reconstruction Louise Callow, CPNP, MSN Pediatric Cardiac Surgery University of Michigan Congenital Heart Center I have no disclosures What We Know, Why We Care, How We Learn • What: – 1 in 5000 live births – Goals S1P consistent • Why: – Resource utilization – Morbidity significant, mortality high – Belief that MBTS and associated low DBP created tenuous hemodynamics • How: – Single Ventricle Reconstruction Trial (SVR Trial) – The Tale of Two Shunts www.wikipedia.org Rosenthal D. Single Ventricle Reconstruction Trial. A work in Progress. Circulation, 2014; 129:200-2001. SVR Trial: Searching for Answers • NHLBI in association with PHN • 15 clinical centers from May 2005 to July 2008 • 549 neonates randomized to RVPAS (N=274) or MBTS (275) • Primary outcome transplant free survival at 12 months SVR Trial Outcomes • Overall: – 54% mortality S1P hospitalization – 33% mortality interstage • Shunt: The winner? – RVPAS lower freedom from death or OHT at 12 months (74% vs 64%) – Really?????? Ohye RG et al. N Engl J Med 2010;362:1980-1992. The Tale of Two Shunts – No difference clinical sequelae, cause of death (cardiovascular) or early mortality – ESV and EDV lower, EF higher in RVPAS – No difference in MAP, although DBP higher with RVPAS – MBTS mortality higher early, RVPAS later – Effects of shunt choice neutralized by 14 months Norwood Operation—S1P • S1P – Arch reconstruction – Controlled PBF through shunt – Nonrestrictive ASD • Parallel circulation – Output determined by relative resistance between circulations • Decreased ventricular mass • Cardiac output twice normal at baseline • Increased oxygen demand – Surgical trauma – Myocardial edema/inflammation from CPB – Post ischemic RV www.blogspot.com Goals of Postoperative Care • • • Balancing the parallel circulation – PBF for oxygenation – SBF for aerobic metabolism, avoid volume load on SV – SVR/PVR Matching oxygen delivery, demand and consumption – Dependent on optimizing CO – Maintain end organ function Remember the shunt – MBTS: afterload reduction, vasopressors for DBP, manipulation of ventilation – RVPAS: maintain RVEF for PBF, inotrope, volume, HR control Migliavacca F et al. Modeling of the Norwood circulation: effectsof shunt size, vascular resistances and heart rate. Am J Physiol Heart Circ Physiol. 2001;280:2076-2080. DO2 and SaO2 - Increase CO increase Qp:Qs and SaO2 - DO2 declines DO2 and SvO2 - SvO2 /DO2 better, more accurate predictor DO2/demand balance - Only value predict mortality - SvO2 <40% reflects critical decrease in DO2 DO2 and AVO2 Difference - Optimal DO2 for any CO Qp:Qs < 1 − Qp:Qs lower DO2 and wider AVO2 difference Qp:Qs and DO2 Assumptions about PvO2 - Errors in PVO2 lead to serious miscalculation of Qp:Qs - Is there a better way? The Ω Factor SaO2/SaO2-vO2 - Reflects relative excess DO2 - Ratio of DO2 to consumption - Linear relationship with CO - PVO2 irrelevant - High Ω high DO2 Oxygen Consumption and DO2 The Patient Issue: Parts of S1P - Sedate/paralyzed? - Fretful? - Seizure? - Fever/infection? - NPO or feeding? Change consumption change slope of relationship Ω and DO2 Goal Directed Therapy Remember: - Slight increase in SaO2 may create large decrease in DO2 Low SvO2 indicate low DO2 Estimating Qp:Qs leaves potential for errors Ω linearly related to DO2 and not effected by change in CO and PV saturation Balanced circulation maintains DO2 and demand, CO, O2 capacity, O2 consumption and pulmonary oxygenation Balanced or not if lactate high/trending tissue oxygen deficit exits Goal Directed Therapy Pulmonary Undercirculation • • • • • • SaO2: 60-65% SvO2: 40% A-V O2 difference: 20-25 Qp:Qs: <1 Ω: 2-3 Lactate: >4, uptrending Barnea O et al. Balancing the Circulation: Theoretic Optimization of Pulmonary/Systemic Flow Ratio in Hypoplastic Left Heart Syndrome. 1994;24:1376-1381. Goal Directed Therapy Regain balance: SVR PVR • Preload for volume loading, contractility, HR and AV synchrony • Mild hyperventilation, oxygen, iNO, FRC • Increase SVR, alpha agents, hypertension • Decrease demand/consumption • Maintain O2 carrying capacity • Treat acidosis, correct electrolytes • Mechanical issue: too small? tamponade? • Anticoagulation • Fluid balance Goal Directed Therapy Pulmonary Overcirculation • • • • • • SaO2: 80-85% SvO2: <40% A-V O2 difference: >45 Qp:Qs: >2 Ω: 2 Lactate >4, uptrending Goal Directed Therapy Regain Balance: SVR PVR • Preload, contractility, HR • Mild hypoventilation, hypoxic gases, FRC, PEEP, PPV • Decrease SVR • Match DO2, demand and consumption • Mechanical issues: too big? • Treat acidosis, electrolytes • Fluid balance • ECMO Photiadis J et al. Optimal pulmonary to systemic blood flow ratio for best hemodynamic status and outcome early after Norwood operation. European J Cardio-thorac Surg. 2006;29:551556. • It’s hard work • Lots of unknowns • Need for improvement in all areas • Quest for knowledge never ending • Nursing SVR trial???????? www.123rf.com