Download Pathophysiologic consideration in patients with congenital

Pathophysiologic
Consideration
In Patients With
Congenital Heart
Disease
SAMIA SHARAF .MD
Professor Of Anaesthesia .. Ain Shams University
Classification Of Congenital Heart
Lesions
1)
1)
1)
Obstructive lesions eg.
Aortic stenosis – coarctation of aorta
Increased pulmonary blood flow eg.
ASD – VSD – PDA
Decreased pulmonary blood flow lesions eg.
Tetralogy of fallot – tricuspid atresia –
pulmonary atresia
Classification Of Congenital Heart Lesions
Left To Right Shunt
Atrial Level : ASD 5% , TAPVC
Ventricular Level : VSD 33%
Great Artery Level : PDA 10%
Truncus Arteriosus : 1%
Coronary Level : ALCAPA
Right To Left Shunt
TOF : 9%
TGA : 1%
Left Heart Obstructive Lesions
Mitral Stenosis
Aortic Stenosis : 8%
Coarctation : 5%
Hypoplastic Left Heart Syndrome
Right Side Obstructive Lesions
Pulmonary Stenosis / Atresia : 10%
Tricuspid Stenosis
Hypoplastic Right Heart
Single Ventricle
Others
Vascular Rings
Venous Anomalies
Arteriovenous Fistula
Clinical Presentation Of Children
With CHD
1)
2)
3)
4)
Cyanosis ( due to hypoxia )
Respiratory system abnormalities
Cardiac failure
Arrhythmias
Cyanosis
Pathophysiologic Effects of Hypoxia
(1) Growth
(2) Heart

Exercise intolerance :
myocardial dysfunction
ventricular compliance and contractility

Irreversible myocardial damage .

Increased sympathetic tone
down regulation of beta receptors
cardiomyopathy
(3) Hematology

A major adaptive response to chronic hypoxia
Red cell mass
Polycythemia


Secondary Spherocytosis
Blood viscosity
Risk of thromboembolic events
Hemostasis :
Polycythemia
Coagulation
abnormalities
Primary
fibrinolysis
DIC
Mechanism of coagulation abnormalities
DIC
Hypercoag.
blood &
tendency to
bleed
Thrombocyt
openia &
Low
Fibrinogen
& Other
Factor Level
Increased
blood
viscosity
Increase
intravascular
strains
Consumpution
of platlets ,
fibrinogen ,
factor V , VIII
Fibrin
deposition
&
platlet
aggreg.
(4) CNS



Chronic hypoxia causes impairment of
neurologic development and increase risk of
neurologic damage .
Brain abscess : Rt. – Lt. shunt
Cerebrovascular thrombosis and hemorrhage .
Respiratiry System Abnormalities


Anatomical abnormalities of airway
Pulmonary abnormalities associated with
pulmonary blood flow .
or
Anatomical Abnormalities Of
Airway
1)
2)


Short trachea eg. interrupted aortic arch
large airway obstruction : ( trachea & bronchi )
Compression by enlarged aorta or
pulmonary artery .
Upwards displacement and increase angle of
bifurcation of trachea by enlarged LA .
3)
•
•
Small airway obstruction :
Compression of lung parenchyma by
enlarged heart and vessels .
Pulmonary hypertension .
Pulmonary Changes Associated
With
Pulmonary Blood Flow
Patients with chronic hypoxia
1)
Slight of alveolar ventilation
2)
pulmonary venous PO2 is high
3)
V/Q mismatch
alveolar –
pulmonary venous O2 gradient
4)
Physiological dead space
end tidal
CO2 is lower than arterial PaCO2
Pulmonary Changes Associated
With
Pulmonary Blood Flow



Obstruction of small airway
Pulmonary congestion
pulmonary
compliance , lung water & Impaired gas
exchange
Progressive
of pulmonary vascular
resistance due to hypertrophy in muscular
layer of pulmonary arteries
reverse of left
to right shunt
Cardiac Failure
Causes of limited cardiac reserve :
(1) Increased cardiac workload
Pressure overload :
ventricular outflow tract obstruction
SVR
blood viscosity
Volume overload :
* Valvular insufficiency
* Single ventricle
* Left – right shunt
(2)




Myocardial contractility:
Prolonged workload of myocardium
Vascular supply to ventricles
Blood hyperviscosity
Chronic hypoxia
Compansatory Mechanism



Ventricular hypertrophy
Adrenergic system changes
Activation of B receptors
Renal system compansation
*Salt & water retention
*Renin secretion
Arrhythmias
Types :
* Congenital
* Acquired
Etiology :
 Intrinsic electrophysiology abnormalities
 Damage from chronic hypoxia – hemodynamic stress
 Surgical injury eg. F4 , Fontan operation , atrial
correction of TGA
Congenital Conduction System
Abnormalities




Congenital complete atrioventricular block
Wolf – Parkinson white syndrome
Supraventricular tachycardia
Arrhythmias associated with Ebstien anomaly
Acquired Conduction System
Abnormalities


Non surgical : rare
Surgical by :
* cardioplegia
* mechanical retraction
* ischemia
* metabolic abnormalities
Why we are conserned
about the
pathophysiology of CHD
Provide Safe
Anaesthetic
Technique
Decrease
Anaesthetic
Risk
Anaesthetic Risk
factors affecting anaesthetic risk in congenital heart disease
Pulmonary
disease
Myocardial
dysfunction
Cyanotic heart
disease
Cardiovascular
impairment
Arrhythmias
Magnitude
of surgery
Anaesthetic risk
How To Reduce Anaesthetic Risk ??
1
• Consultation
2
• Surgical Status
3
• How To Look To
The Data
Consultation
Role Of Surgeon
Case discussion :
Pts. with CHD may not tolerate :
 Abdominal laparoscopic procedures
( eg. stenotic valvular lesions , single ventricle )
 Absorption of CO2 ( C.O.P dependant low PVR) .
 One lung ventilation
 Prone position ( Fontan pt. )
Role Of Pediatric Cardiologist
Preoperative consultation
sometimes add a little
benefit to anesthiologist
!!!!!
History data
exact anatomy
Previous cardiac operation
Myocardial function status
Murmurs
Gallops
Pulse in extremities
Pediatric
cardiologist
consultation
Base line O2
saturation
Vital data
Planned followup
as needed
2-3 months interval
New echo
Unstable pt.
Major operation
Surgical Status
Of The Patient
Untreated
Cured
Corrected
Palliated
*Normal life
expectancy
*Normal CV
reserve
*No further
medical ttt
*Markedly
prolonged life
expectancy
*Some limitation
of cardiac
reserve
*May require
further medical
ttt
*Prolonged life
expectancy
*Definitly
abnormal CV
physiology
*Certainly require
medical or
surgical ttt
Efficacy Of Repairs For CHD Lesions
CURED
PDA
ASD
CORRECTION
VSD
TFO
Coarctation of aorta
Pulmonary or aortic stenosis
AV Canal repair
PALLIATION
Conduits
PA banding
Modified Glenn shunt
How To Look To Patient Data
DATA
History Taking
o Growth
o Exercise Intolerance
o Recurrent Chest Infection
o Syncopal Attacks
o Squatting
ECG , Echo & Cardiac Cath.
Systolic & Diastolic Dysfunction
Systolic Dysfunction
Reduced Fractional Shortening
Diastolic Dysfunction
Ventricular Hypertrophy
Concentric
Eccentric
Obstructive
Before
Repair
e.g
valvular
&
outflow
obst.
After Repair
e.g
Homograft
conduit
Volume
Before
Repair
e.g
Lt . to Rt.
shunt
After
Repair
e.g
•Pulmonary
valve regurge
( F4 )
•MV repair
Anaesthetic considerations :
Consider determinants of coronary
perfusion & myocardial oxygen balance
• Heart rate changes
• Hypotension
• Myocardial contractility
Anaesthetic considerations
Cardiomyopathy
RV
increase wall
thickness
coronary
filling
becomes
diastolic
coronary
perfusion
depends on
bl. p. & hr
LV
anaesthetic
myocardial
depression
Decrease driving
filling pressure
of coronary
arteries
Coronary
ischemia
Maintain heart rate
to decrease
regurgitant
fraction
Syst. Dysfunction
In Dialted type
Diast.
Dysfunction
In Hypertrophic
& restrictive
type
Residual Shunts :
o Occasionally present after repair of ASD ,
VSD & F4
o Small patch leaks are hemodynamically
benign
Dysrhythmias :
Atrial & ventricular types increase mortality and
morbidity
Arrhythmias Associated With Specific
Surgical Procedures
Ostium secondum ASD :
• P-R interval is prolonged in 20-30% of patients
• AF , atrial flutter with advancing age
VSD :
•RBBB
•Atrial ectopic , junctional beats , premature ventricular
beat
•Late onset of complete heart block or ventricular
arrhythmias are rare
Repair of F4 :
•RBBB & complete heart block
Mustard or Senning operation :
•Sinus nodal dysfunction
•Bradycardia
•A-V block , AF
Pulmonary hypertension
Severity of hypertension of base line PAH correlated with the
incidence of major complications
( pulmonary hypertensive crisis or cardiac arrest )
Cardiovascular risk of PAH
Major perioperative hemodynamic deterioration
mainly pulmonary hypertensive crisis and acute right
ventricular failure and cardiac arrest .
Data to look for :
o Mean pulmonary artery pressure > 25 mmHg
o Severity of base line PH :
Subsystemic PAP < 70% of syst. bl. pressure
Systemic PAP = 70 – 100 of syst. bl. pressure
Suprasystemic PAP > 70 of syst. bl. pressure
( based on mean pressures )
ANAESTHETIC CONSIDERATIONS
Avoid Factors Rapidly Increasing PVR
Laboratory data
Hematocrit value
HCT.
Decompansated
Erythrocytosis
Increase Red Cell Mass
Increase
Erythropoitin
Level
Increase More Blood Viscocity
Hyperviscosity
symptoms
Decreased oxygen
delivery
Blood Indicies :
Iron Deficiency Anaemia
Microspherocytosis
Low Hemoglobin
Concentration
Rigid Cell
Membrane
Increase Blood Viscosity
Hyperviscosity Symptoms At Lower
Hematocrit Value
Phlebotomy
Done to relieve hyperviscosity symptoms with
hematocrit > 65 % in absence of iron deficiency
anaemia or signs of dehydration
Hemostatic values
•Prolonged PT , PTT , APTT values most
frequently seen in cyanotic patients
•Thrombocytopenia is related to degree of
polycythemia .
Summary
General associated risk factors in CHD
 Severe form of isolated lesion
 Complex lesions
 Concurrent infectious disease
 Congestive heart failure
 Acute hemodynamic deterioration
 Previous palliative or corrective procedures
Summary
Risk criteria of hemodynamic critical impairment
in perioperative period in CHD
•
•
•
•
•
•
Arterial saturation < 75 %
Hematocrit > 65 %
Qp / Qs > 2 : 1
LV outflow tract gradient > 50 mmHg
RVOT gradient > 50 mmHg
PVR > 6 wood units
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