Download Atrioventricular Septal Defect

Management of the Patient
with AV Canal
Lindsey Justice, MSN, RN, CPNP-AC
CICU Nurse Practitioner
The Heart Institute
Cincinnati Children’s Hospital Medical Center
AV Canal Classifications
• Complete AV canal: primum ASD, inlet VSD, common AV
valve
– Rastelli type A: 75%, the superior common leaflet cleft is over the
crest of the septum, with chordal attachments between the leaflet and
septum
– Rastelli type B: rare, chordal attachments straddle septum to the left
– Rastelli type C: 25%, superior leaflet with no chordal attachments to
the septum, most common type in TOF and other assoc. defects
• Partial AV canal defect: primum ASD, no VSD, cleft mitral
valve
• Transitional AV canal defect: partial defect with inlet VSD
that is partially obstructed by chordal attachments
Unbalanced AV Canal
• Present when the common AVV opens predominantly
toward one ventricle or the other
• If the common AVV opens predominantly into the
morphologic left ventricle = LV-dominant AV canal
• If the common AVV opens predominantly into the
morphologic right ventricle = RV-dominant AV canal
• Varies from mildly unbalanced with 2 nearly normal-sized
ventricles to severely unbalanced with a single dominant
ventricle and a second hypoplastic ventricle
• Single-ventricle physiology and surgical management
Physiology
• Hemodynamics depend on:
– Size of the ASD and VSD
– Competency of AV valve
– Pulmonary vascular
resistance (PVR)
• newborn period-PVR  thus
minimal shunting of blood
• PVR falls over time (normal by
6-8 weeks)
– left to right shunting increases and
pulmonary blood flow increases,
results in CHF symptoms
– If no CHF then PVR is 
Trisomy 21 (Down Syndrome)
• 40% of children with
Down Syndrome have
CHD
– 40% of the defects are AV
canal
– Generally fare better than
non-Down Syndrome AVC
Considerations with Trisomy 21
• Pulmonary hypertension
• Airway abnormalities
– Tracheal stenosis
• Thyroid disorders
• GI tract abnormalities
(12%)
–
–
–
–
TE fistula
Duodenal atresia
Omphalocele
Hirschprung disease
Loukanov et al. JTCVS 2005
– Laryngo/Tracheomalacia
• CNS abnormalities
– Hypotonia
– Seizures (<9%)
• Difficulty with sedation
– Use of Precedex
• Difficulty with vascular
access
Sulemanji et al. Anaesthesiol Scand 2009
Kalyanaraman et al. Pediatr Cardiol 2007
– PCICS Post-op Guideline
Trisomy 21 and Pulmonary
Hypertension
• 42 patients undergoing pulmonary hypertension
study protocol in cath lab
• Baseline, FiO2 1.0, then add 20,40,80 ppm iNO
• 11 Trisomy 21 patients (7 CAVC) vs. 31 without
chromosomal abnormalities
• 42% PVR decrease with O2 + iNO in non Trisomy 21
• 21% PVR decrease with O2 + iNO in Trisomy 21
(p=0.02)
• Conclusion: Patients with Trisomy 21 may be less
responsive to iNO
Cannon et al. Pediatr Cardiol 2005
Trisomy 21 - Hypothyroidism
• Incidence is 32.5%
Purdy et al. J. Perinatol 2014
• Pre-op thyroid screening is essential
• Subclinical hypothyroidism is common, may
decrease myocardial contractility and cardiac
output
Biondi et al. 1999; Di Bello et al. 2000; Kahaly 2000
• Hypothyroidism associated with:
–
–
–
–
longer mechanical ventilation and O2 supplementation
greater use of epinephrine
greater use of furosemide
longer CICU LOS (p<0.0001)
Bettendorf et al. Pediatr Res 1997
Thyroid Hormone
• Thyroid hormones have important effects on
cardiovascular function
–
–
–
–
 Preload
 Afterload
 Contractility
 Heart rate
• T3, T4, and TSH levels are significantly depressed following
cardiac surgery
• Results of T3 repletion in children following cardiac surgery
are mixed and optimal dosing is unknown
King et al, Ir J Med Sci 2014; Bettendorf et al, Lancet 2000; Chowdhury et al, JTCVS 2001
AV Canal Surgical Repair
• Timing of surgical repair:
– Amount of CHF and
pulmonary overcirculation
– Size and age of infant
– Typically 4-6 months
• Surgery:
–
–
–
–
Cardiopulmonary bypass
Closure of ASD
Patch closure of VSD
Valve repair and division
(determined by number of
leaflets on common valve)
– Extent of valve involvement
crucial
Postoperative Concerns
• Low cardiac output syndrome
• Residual or Recurrent Lesions
– VSD
– Left AV valve stenosis or insufficiency
• Arrhythmias/Heart Block
• Pulmonary Artery Hypertension
Low Cardiac Output Syndrome
• LCOS: transient decrease in CO due to myocardial
dysfunction, results in inadequate oxygen delivery.
• High risk following cardiac surgery requiring CPB
• Evaluation:
– Tachycardia, diminished urine output, elevated lactate, low SVO2
and hypotension (late sign)
• Treatment:
– Volume administration for inadequate preload
– Inotropic support to improve contractility
– Consider afterload reduction if SVR is elevated or to assist with AV
valve regurgitation
– Support right ventricular function, treat PAH
Koo et al., PCICS Guidelines 2014
Residual or Recurrent Lesions
• Lesions include:
– LVOTO obstruction (Partial or Transitional AVSD)
– AVV regurgitation and/or stenosis
– Intracardiac shunt (ASD or VSD)
• Intraoperative TEE essential in detecting
residual lesions
– Underestimates AVV regurgitation
• Low threshold for postoperative TTE in patients
not progressing appropriately
Chowdhury et al. JTCS 2009
Honjo et al. Ann Thorac Surg 2006
Kim et al. Ann Thorac Surg 2005
Medical Treatment of Left AVVR
• Nipride or Milrinone
• ACE inhibition:
– Reduces severity of MR
– Improves cardiac performance
– Promotes ventricular remodeling
Calabro et al. Am Heart J 1999
Momma Pediatr Drugs 2006
Operative Treatment of Left AVVR
Gillespie et al. Cardiol Young 2006
Post-operative Arrhythmias
• Rhythm disturbances decrease cardiac output
– Cardiac Output = Heart Rate x Stroke Volume
– Bradycardia decreases amount of blood ejected per
minute
– Tachycardia decreases diastolic filling time (stroke
volume) while increasing myocardial oxygen demand
• AV Synchrony assures optimal ventricular filling
(atrial kick = 15% of SV), especially important in
the setting of LCOS
Koo et al., PCICS Guidelines 2014
Post-operative Arrhythmias
Post-operative arrhythmias are common (15%)
AVSD repair independent risk of arrhythmia
Delaney et al. JTCVS 2006
Post-operative Arrhythmias - Treatment
• Epicardial pacing wires can be diagnostic and
therapeutic
• Can NOT predict who will need them
– Moltedo et al. 2007
• Transesophageal pacing is a good alternative in
supraventricular arrhythmias
Post-operative Junctional Tachycardia
• Anatomic substrate is unknown
• “Narrow complex” tachycardia
– AV dissociation (Atrial rate < Ventricular rate)
• Major cause of postoperative morbidity and
mortality
– Increased ventilator time/CICU stay
Dodge-Khatami et. al. 2002
Post-operative Junctional Tachycardia
Post-operative Junctional Tachycardia
• Address what is modifiable
–
–
–
–
Temperature
Electrolytes (K, Ca+2, Mg+2)
Catecholamines
Sedation (Precedex)
Rajput et al. Ann Pediatr Cardiol 2014; Chrysostomou et al. Anesth Analg 2008;
Munoz et al. Anesth Analg 2008
• Restore AV Synchrony
– IV Amiodarone or pacing
• Initiate early treatment
– Faster time to rate and rhythm control
– Less amiodarone
Hass et al. JTCVS 2008
– Shorter ICU LOS
Post-operative Complete Heart Block
• AV synchrony is important
– Transesophageal atrial sensing
• No data on efficacy of steroids
Spontaneous recovery in
66% of patients
• 95% by POD #10
Weindling et. al., Am. J. Cardiol. 1998
Pulmonary Artery Hypertension
(PAH)
• Most patients with high flow, high pressure and
low PVR lesions (CHF) will not require therapy
for postoperative PAH
• Risk stratification is mainly clinical as cardiac
catheterization and lung biopsy are not
routinely performed
• Risk factors:
– Extracardiac syndromes (Down syndrome)
– LA hypertension
Bando et al. JTCVS 1996
Lindberg et al. JTCVS 2002
PAH Crisis
• What is it?
– Spasm of pulmonary arteries and vasculature
– Results in decreased pulmonary blood flow
– Decreased pulmonary blood flow leads to
decreased cardiac output
• What can cause it?
– Increased PVR
– Agitation, pain, and suctioning
– Spontaneous
PAH Crisis
Symptoms
1. No ∆ or HR (early)
2. Acute  in PA pressure
3. CVP/RA
4.  End Tidal CO2
5.  sats
6.  pulses& perfusion
7. HR BP ( late)
8. Metabolic acidosis
**The
key is to avoid a crisis!
• No unnecessary
stimulation
• May require premedication before care
such as ETT suctioning
• Recognize symptoms and
intervene early
PAH Crisis Management
•
•
•
•
•
•
•
100% FiO2
Sedation, +/- paralysis
Sodium bicarb administration
Bag patient, slightly hyperventilate
Minimum amount of PEEP to keep FRC
Nitric oxide (iNO)
Volume administration
If these treatments fail:
CPR/resuscitation
ECMO
CAVC and Post-Bypass iNO
• 124 patients, prospective, randomized, placebocontrolled study of prophylactic iNO 10 ppm
– Infants at high risk for pulmonary hypertensive crises
– 30% had CAVC
• No differences in mortality
– (5 iNO vs. 3 placebo, p=0.49)
• Conclusion: routine
prophylactic use of iNO in
high risk patients reduces
PAH crises and time to
extubation
Miller et al. Lancet 2000
iNO and Milrinone for Post
CPB PAH
• 90 patients randomized in three groups:
• iNO 30 ppm
• Milrinone 0.5 mcg/kg/min
• iNO 30 ppm + milrinone 0.5 mcg/kg/min
• Mean PAP recorded
• Baseline, 10 and 20 minutes after drug start, 10 minutes
after cessation in drug regimen
• Larger decrease in mPAP with both drugs: 16% greater
(p<0.05)
• Conclusion: both drugs together produce larger
decrease in mPAP in post-CPB
Khazin et al. J Cardiothorac Vasc Anesth 2004
Conclusions
• AV Canal is associated with Down Syndrome; thus other
considerations of Down Syndrome are relevant for
management (Hypothyroid, Vascular access, Sedation)
• Patients without pre-op CHF indicates increased PVR and
should heighten concern for pulmonary hypertension
symptoms post-operatively
• Common post-operative problems include:
– LCOS
– Arrhythmias (JET or CHB)
– Residual lesions (left AVVR, ASD/VSD, or LVOTO)
– PAH
• Consider the PCICS Postoperative Management Guidelines