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SINGLE VENTRICLE PHYSIOLOGY Sarah Tabbutt MD PhD Director Cardiac Intensive Care, Benioff Children’s Hospital Associate Professor of Pediatrics University of California, San Francisco

Friday, June 29, 12


View from the ICN

PATIENT PHOTOS WITH CONSENT Friday, June 29, 12


SINGLE VENTRICLE PHYSIOLOGY • ductal

dependent

• shunt

dependent

• cavopulmonary • fontan

Friday, June 29, 12

anastomosis


DUCTAL DEPENDENT • in

general, the ductus arteriosus is an unrestrictive aortopulmonary shunt when being maintained with prostaglandin infusion

Friday, June 29, 12


BALANCING SYSTEMIC AND PULMONARY BLOOD FLOW • Qp:Qs

is the ratio of pulmonary to systemic blood flow

• High

Qp:Qs relatively more pulmonary blood flow

Friday, June 29, 12


BALANCING SYSTEMIC AND PULMONARY BLOOD FLOW • Qp:Qs

is the ratio of pulmonary to systemic blood flow

• Low

Qp:Qs relatively more systemic blood flow

Friday, June 29, 12


BALANCING SYSTEMIC AND PULMONARY BLOOD FLOW

• Qp:Qs

reflects pulmonary versus systemic vascular resistance

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DOES A OXYGEN SATURATION OF 80% MEAN THE QP:QS IS 1:1? 80%

Friday, June 29, 12


DOES A OXYGEN SATURATION OF 80% MEAN THE QP:QS IS 1:1? 80% 100% 60%

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Qp:Qs = 1:1 good systemic perfusion AVO2 = 20


DOES A OXYGEN SATURATION OF 80% MEAN THE QP:QS IS 1:1? 80% 100% 20%

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Qp:Qs = 3:1 poor systemic perfusion AVO2 = 60


TYPICAL PREOPERATIVE SCENARIO 90% 100% 65%

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Qp:Qs = 3.5:1 adequate systemic perfusion AVO2 = 25


PREOPERATIVE QP:QS DECREASE

Increase PVR Decrease SVR inspired CO2 hypoxic gas mixture acidosis benzodiazapenes alpha blockers Friday, June 29, 12

Qp:Qs

INCREASE

Decrease PVR Increase SVR oxygen iNO hyperventilation PGE fever, agitation


HIGH QP:QS WITH SYSTEMIC HYPOPERFUSION •

example: HLHS with unbalanced atrioventricular canal •

no restriction at atrial septum

pulmonary over-circulation

diminished systemic perfusion

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INSPIRED GAS MIXTURES • hypoxic

gas mixture Wessel, JTVCS, 1996

• inspired

carbon dioxide Jobes, Ann Thorac Surg, 1992

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INSPIRED GAS MIXTURES • Pre-operative

neonates with HLHS under conditions of anesthesia and fixed minute ventilation.

• Prospective, randomized, crossover

trial comparing hypoxia (17% FiO2) to hypercarbia (2.7% FiCO2).

• SVC

gas.

(SvO2) and arterial (SaO2) co-oximetry and blood

• NIRS

determined cerebral mixed oxygen saturation (ScO2).

Tabbutt, Circulation, 2001

Friday, June 29, 12


INSPIRED GAS MIXTURES

• both

hypoxia (p = .06) and hypercarbia (p = .03) decreased the Qp:Qs

Tabbutt, Circulation, 2001 Friday, June 29, 12


difference between condition and baseline

INSPIRED GAS MIXTURES SaO2

ScO2

SvO2 p=.02

p=.0001

AVO2 ns ns

p=.002 p=.001

hypoxia

p=.009 p=.005

hypercarbia Tabbutt, Circulation, 2001

Friday, June 29, 12


INSPIRED GAS MIXTURES • Assuming

oxygen consumption remains constant, oxygen delivery is unchanged during hypoxia and increased during hypercarbia.

• The

relative effects on cerebral vs. systemic oxygen delivery could not be distinguished.

Friday, June 29, 12


DUCTAL DEPENDENT BABIES IN THE CURRENT ERA • Natural

airway (room air)

• tolerate • PGE

(lowers PVR)

• low

dose 0.01 mcg/kg/min

• Palliation

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tachynpnea

within first week of life


EVOLUTION IN MANAGEMENT 1980

1990

2000

2010

increase pulmonary vascular resistance

decrease systemic vascular resistance milrinone, phenoxybenzamine

avoid oxygen

use oxygen

dopamine, epinephrine

low dose dopamine

paralysis

early extubation

high dose narcotics

low dose narcotics

Friday, June 29, 12


HISTORICAL POSTOPERATIVE MANAGEMENT • Avoiding

a high Qp:Qs and compromised systemic blood flow by manipulation of PVR • avoidance • inspired

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of oxygen

carbon dioxide


CURRENT POSTOPERATIVE MANAGEMENT

•a

well sized shunt provides appropriate resistance to pulmonary blood flow

• management

reducing SVR

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focused on


PHENOXYBENZAMINE: HLHS AVO2

p = .02

Qp:Qs p = .014

hours tweddell, Ann Thor Surg, 1999

hours Friday, June 29, 12

used at approximately 10% of centers


OPTIMIZING MIXED VENOUS SATURATIONS • continuous

in SVC

SVO2 monitoring

• NIRS • goal

directed therapy to maximize SVO2 Ghanayem, JTCVS, 2010

Tweddell, Ann Thorac Surg, 2007 Friday, June 29, 12


MILRINONE: HLHS used at over 90% of centers following stage 1 palliation

wernovsky, cardiol young, 2007

-100 mcg/kg load on bypass -modified ultrafiltration increases plasma concentrations 35% zuppa, anesth analg, 2006 -0.2 mcg/kg/min infusion

Friday, June 29, 12


PaO2 (torr) SvO2 (%) AVO2 (%)

low oxygen (30%)

high oxygen (100%)

40

56 (P < .01)

44

54 (P < .01)

36

36

100% FiO2 improves oxygen delivery following the Norwood procedure for HLHS Friday, June 29, 12

bradley, jtcvs, 2006


OXYGEN IS HELPFUL • ventilator

may be on 21-30% oxygen

• hand

ventilate for suctioning on 100% oxygen • watch

arterial blood pressure and heart rate while suctioning

Friday, June 29, 12


POSTOPERATIVE CARE

• anticoagulation • enalapril

Friday, June 29, 12


SHUNT THROMBOSIS

hlhs with mbts thrombosis Friday, June 29, 12

following balloon angioplasty


HEPARIN •

acute shunt failure is less common

Children’s Hospital of Philadelphia 2002 - 2005 •

206 patients with shunts

early shunt thrombosis requiring reintervention in 3%

shunt re-intervention associated with ECMO, 3%

shunt re-intervention associated with CPR, 1.5%

O’Connor, Ann Thor Surg, 2011

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heparin •

postoperative low-dose

no data


ASPIRIN •

hlhs, norwood (n = 323)

2001 - 2005

aspirin decreased one-year non-surgical mortality (hazard ratio 0.34, p < .oo1)

no difference in low (<20mg) vs high (>40mg) dose

li, circulation, 2007 Friday, June 29, 12


multicenter, randomized, placebo controlled

32 countries, n = 906

infants < 3 months with AP shunt

randomized to plavix (0.2mg/kg/day) vs placebo

primary outcome was death, shunt thrombosis or cardiac procedure prior to 120 days of age

88% of subjects on aspirin

no difference found in composite or individual endpoints

no difference in bleeding events

Friday, June 29, 12

PLAVIX

Wessell, abstract , AHA, 2010


ENALAPRIL •

2003 - 2009, n - 185

double blind, placebo controlled

shunted single ventricle patients following stage 1 acute post-op phase

follow up at 14 months

no difference in height or weight

no difference in ejection fraction by echo

trial does not support empiric use of enalapril

Friday, June 29, 12

Hsu, Circulation 2010


alexa, HLHS, 4 years, s/p Fontan Friday, June 29, 12


THANK YOU Friday, June 29, 12


BIDIRECTIONAL GLENN: PREOPERATIVE EVALUATION •

Cardiac output (AVO2, MRI)

Atrioventricular valve regurgitation (MRI, echo)

Venous anatomy (angio, echo, MRI)

Pulmonary artery size (angio, MRI)

Aortopulmonary collaterals (angio)

Pulmonary vascular resistance (cath)

Pulmonary ateriovenous malformations

Other anatomic issues (atrial septum, arch)

Qp:Qs (cath, MRI)

Friday, June 29, 12


a children's hospital was formed in Boston and by the 1870's there were children's hospitals extending from Albany in the east to San Francisco in the west. Pediatrics was well on its way.

INSPIRED GAS MIXTURES

The hotbed for innovation, and the model for other children's hospitals, would continue to be in Philadelphia at Children's Hospital. It is here that the various specialties that now make up pediatrics evolved.

hypoxic gas mixture

â&#x20AC;˘ From the outset, some of the nation's outstanding pioneers in pediatric research and clinical care have been part of Children's Hospital. The succession of great names whoJTVCS, have1996 passed through the Wessel, Hospital includes: Sir William Osler, Joseph Stokes, Jr., C. Everett Koop, Gertrude and Werner Henle, Stanley Plotkin, William Rashkind, Audrey Evans and others. Early on, leaders at Children's Hospital recognized the importance and synergy of a vibrant environment for research and education. The pediatricians at Children's Hospital comprise the pediatric teaching department at the University of Pennsylvania Medical School, consistently ranked among the best in the nation. Researchers here have â&#x20AC;˘ discovered genes, pioneered new treatments, and developed vaccines. Jobes, Ann Thorac Surg, 1992

inspired carbon dioxide

These ingredients for excellence have long been bolstered by the support of a dedicated community. As a charitable, non-profit hospital, Children's Hospital has Friday, June 29, 12


VENTRICULAR DYSFUNCTION

• Children’s

Hospital of Philadelphia

• 2005-2009, 213

subjects; 19 (9%) with dysfunction; nearly all HLHS

• function

by ECHO at 5 months post BDG • 60%

improved

• 35%

unchanged

•3

died, 1 transplanted O’Connor, Pediatr Cardiol 2011

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PREOPERATIVE QP:QS Qp:Qs Restrictive or absent PDA in patient with hypoxemia due to limited pulmonary blood flow: -severe TOF -neonatal Ebsteins -single ventricle with severe PS or sub-PS

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INCREASE

Decrease PVR Increase SVR oxygen iNO hyperventilation phenylephrine prostaglandin


PREOPERATIVE QP:QS Qp:Qs DECREASE

Increase PVR Decrease SVR inspired CO2 hypoxic gas mixture hypoventilation benzodiazapenes alpha blockers avoid fever, agitation Friday, June 29, 12

Unrestrictive PDA, with signs of inadequate systemic perfusion: -low DBP -acidosis -low urine output -decreased oxygen saturations


POSTOPERATIVE QP:QS Restrictive Shunt DECREASE

Decrease SVR

milrinone phenoxybenzamine sedation Friday, June 29, 12

Qp:Qs

INCREASE

Increase SVR epinephrine norepinephrine vasopressin agitation fever

Presentation 12 - Tabbutt  

Presentation 12 - Tabbutt

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