Transcript Anaesthesia for Acyanotic Congenital Heart Disease

ANAESTHESIA FOR PATIENT WITH VSD
UNDERGOING NON CARDIAC SURGERY
Dr. Adham A.monem Saleh, M.D.
Lecturer of Anesthesia, Intensive care, and Pain
management.
Ain Shams university
Situation
A male child 5 years old, presented to the ED with acute
appendicitis. He is a known case of unrepaired VSD. The
decision of open appendectomy was made.
O/E: mild orthopnea, mild wheezes, pansystolic murmur, no
cyanosis.
Preop. labs were within normal range, except for leukocytosis.
Echo: VSD with RVSP=70 mmHg, RV++.
VSD
Most common CHD (20-30%): 2.6 – 5.7 per 1000 live
births.
Types:
I.
Subpulmonary (5 – 7 %) , ass. With aortic valve
insufficiency
II.
Perimembranous (80% ) , ass with tricuspid valve
abnormality
III. AV canal (5 – 8 %)
IV.
Muscular (5 – 20%)
ANATOMY
Pathophysiology

L→R shunt predominantly during systole. The
septal defect is anatomically close to the RVOT
such that the shunted blood bypasses the RV
cavity. Hence RV hypertrophies sec to pul. HTN
only.

Adaptive mechanisms include ↑Stroke volume,
contractility, Heart rate & myocardial mass.
FEATURES OF VSD BASED ON SIZE
Shunt
Gradient
↑PVR
RVP
RVH
Small
L→R
High
─
N
No
Med
L→R
20mmHg
±
mild↑
Mild
Large
L→R R→L
None
+
↑
Yes
Large with
↑ PVR
R→L
None
+
↑↑
Yes
Natural History
- Spontaneous closure of defects <5mm before 2-5 years
of age
- Natural course depends on:
i.
Size of defect
ii.
changes in PVR
iii.
Changes in the above with age




Large defects lead to CHF in infancy (2- 6 weeks of
life)
Failure to thrive
Recurrent Resp. tract infections
Eisenmenger’s syndrome
Clinical features
Cardiomegaly
Restrictive VSD: Pansystolic murmur Left
sternal border radiating across the sternum
Non restrictive VSD:Decrescendo murmur or
absent murmur
ECG: LVH
Echo: LV enlarged , PA dilated
RVH proportionate to degree of PHT
PREOP EVALUATION OF CHD PATIENT
1.
2.
Review underlying anatomy & physiology of cardiac lesion
A.
Previous cardiac surgeries – palliative vs. reparative
B.
Evaluate existing residual or sequelae
Assess other congenital anomalies
3.
Review information from last cardiological examination
A.
Recent cardiac cath, echo
B.
Functional status
C.
Current medication
4.
Assess risk factors
i.
Pulmonary HTN
ii.
Cyanosis
iii.
Arrhythmias
iv.
Vent. dysfunction
6. Review proposed surgical procedure
A.
Elective vs. emergent
B.
Expected length & invasiveness
7. Plan treatment of potential complications
A.
Dysrhythmias
B.
Pulmonary hypertension
C.
Ventricular dysfunction
8. Plan postop. care
A.
Monitoring
B.
Pain management
C.
Cardiology follow up
9. Discuss anesthetic plan & risk with patient/parent
History:


Infants:
 Cyanosis
 Respiratory difficulty
 Failure to thrive
Children
 Chronic cough
 Cyanosis
 Poor feeding
 Failure to thrive
 ↓ activity during exercise
 Fatigue
 Syncope
Examination:
Airway
Cardiac
Respiratory
Investigation:
CBC, Electrolytes
ECG, CXR, ABG
Echo, Cath.
Fasting Guidelines:
Avoid dehydration/hypovolemia
Premedication:
Benefits:
Anxiolysis
↑cooperation
↓separation anxiety
↓cardiovascular liability
Detrimental effects:
Hypoventilation
Hypotension
Pain on administration
INFECTIVE ENDOCARDITIS
Congenital heart disease (CHD)




Unrepaired cyanotic CHD, including palliative shunts and
conduits
Completely repaired congenital heart defect with prosthetic
material or device, whether placed by surgery or by catheter
intervention, during the first 6 months after the procedure
Repaired CHD with residual defects at the site or adjacent to
the site of a prosthetic patch or prosthetic device (which
inhibit endothelialization)
History of IEC
OR Preparation:
Equipment
Anesthesia machine check
Prepare for invasive monitoring
Set alarm limits appropriate for age & patient
Emergency drugs
Infusions & infusion pump
Monitoring
Pulse Oximetry
NIBP
ECG
Capnography
Urine Output, Temperature
CVP
IBP
TEE
Anesthetic Goals
1.
Bubble avoidance
2.
Optimizing O2 delivery & ventilatory
function
3.
↓ L→R shunt
4.
Avoid hypovolemia
Bubble Avoidance:
1.
2.
3.
4.
5.
6.
7.
Remove all bubbles from IV tubing
Connect IV tubing to the venous cannula while there
is free flow of fluid or blood
Eject small amount of solution from syringe to clear
air from needle to hub before injection
Aspirate injection port of 3 way before injection to
clear air
Hold the syringe upright to keep bubbles at the
plunger end
Do not inject the last ml from the syringe
Do not leave a central line open to air
Induction:
In L→R shunts with ↑ pulmonary blood flow, speed of
inhalation induction is unchanged.
“We found more episodes of severe hypotension & an increased
incidence of bradycardia and emergent drug use in the patients
that received halothane than in patients who received
sevoflurane”
(Anesth Analg 2001;92:1152–8)
Intravenous:
Time to appear in systemic circulation is unchanged.
Thiopentone:↓ SVR, well tolerated in normovolemic, stable
patients.
Propofol: Significant ↓ in SVR & MAP.
Ketamine: ↑ SVR, ↑ L→R shunt.
Etomidate: minimal cardiovascular effect.
HEMODYNAMIC GOALS
1.
Reduction of L→R shunt (avoid increased
SVR)
2.
Slight increase in preload as hypovolemia is
poorly tolerated (Why ??)
3.
If there is pulm. HTN, avoid factors that
increase PVR ………………, and avoid decreased
SVR…………
Hypovolemia is poorly tolerated in these
patients, Why ?
The low resistance pulmonary circulation tends to
steal volume from the high resistance systemic
circulation. This is further increased by the
systemic arterial vasoconstriction of hypovolemia.
Intraoperatively

O2 saturation starts to drop,
what happened ???!!!
↑ PVR
PEEP
High airway pressures
Atelectasis
Hypoxia
Hypercarbia
Acidosis
↑ HCT
Drugs
↓ SVR
Anesth. agents
Vasodilators
Neuraxial blocks
Eisenmenger’s syndrome


↑ PVR and Pulm HTN  RVSP exceeds LVSP  reversal
of shunt  hypoxia, cyanosis……., worsened by drop in
SVR.
TTT:
- Decrease PVR: hyperventilate with 100% O2, Pulm.
Vasodilators (NO, Milrinone, Isoprenaline, Dobutamine, PGE1,
Endothelin antagonist “Bosentan”), treatment of the
precipitating cause.
- Maintain SVR: systemic vasoconstrictors
- Combination: Milrinone or Dobutamine /+ Norepinephrine
infusion
CENTRAL NEURAXIAL BLOCKADE ??
Merit:
↓ SVR  ↓ LR shunt.
Demerits:
1)
IPPV allows hypervent & ↓ PVR
2)
Vasodil due to sudden profound fall in SVR can
reverse shunt
PREGNANCY & L→R SHUNTS
Modest L→R shunts are well tolerated during pregnancy
Anaesthetic management should pay attention to:
1.
Care to avoid bubble infusion
2.
LOR to saline rather than air during epidural
catheterization
3.
Early administration of labor analgesia as pain ↑ SVR &
catecholamine release worsening L→R shunt
4.
Slow onset of epidural anaesthesia is preferred
5.
Monitoring of SpO2 & provision of supplementary O2