Pathophysiologic Consideration In Patients With Congenital Heart Disease

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Pathophysiologic Consideration In Patients
With Congenital Heart Disease
SAMIA SHARAF .MD
Professor Of Anaesthesia .. Ain Shams University
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Classification Of Congenital Heart Lesions

• 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

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Classification Of Congenital Heart Lesions
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Clinical Presentation Of Children With CHD

• Cyanosis ( due to hypoxia )
• Respiratory system abnormalities
• Cardiac failure
• Arrhythmias

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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

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• (3) Hematology
• A major adaptive response to chronic hypoxia
• Red cell mass
• Polycythemia Secondary
  Spherocytosis
• Blood viscosity
• Risk of thromboembolic events

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Hemostasis
Polycythemia
Coagulation abnormalities
Primary fibrinolysis
DIC
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Mechanism of coagulation abnormalities
Increased blood viscosity
DIC Hypercoag. blood tendency to bleed
Increase intravascular strains
Fibrin deposition platlet aggreg.
Thrombocytopenia Low Fibrinogen Other Factor
Level
Consumpution of platlets , fibrinogen , factor V
, VIII
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(4) CNS

• Chronic hypoxia causes impairment of neurologic
  development and increase risk of neurologic
  damage .
• Brain abscess Rt. Lt. shunt
• Cerebrovascular thrombosis and hemorrhage .

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Respiratiry System Abnormalities

• Anatomical abnormalities of airway
• Pulmonary abnormalities associated with or
  pulmonary blood flow .

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Anatomical Abnormalities Of Airway

• 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 .

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• Small airway obstruction
• Compression of lung parenchyma by enlarged
  heart and vessels .
• Pulmonary hypertension .

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Pulmonary Changes Associated With Pulmonary
Blood Flow

• Patients with chronic hypoxia
• Slight of alveolar ventilation
• pulmonary venous PO2 is high
• V/Q mismatch alveolar
  pulmonary venous O2 gradient
• Physiological dead space end
  tidal CO2 is lower than arterial PaCO2

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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

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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

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• (2) Myocardial contractility
• Prolonged workload of myocardium
• Vascular supply to ventricles
• Blood hyperviscosity
• Chronic hypoxia

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Compansatory Mechanism

• Ventricular hypertrophy
• Adrenergic system changes
• Activation of B receptors
• Renal system compansation
• Salt water retention
• Renin secretion

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Arrhythmias

• Types
• Congenital
• Acquired
• Etiology
• Intrinsic electrophysiology abnormalities
• Damage from chronic hypoxia hemodynamic stress
• Surgical injury eg. F4 , Fontan operation ,
  atrial correction of TGA

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Congenital Conduction System Abnormalities

• Congenital complete atrioventricular block
• Wolf Parkinson white syndrome
• Supraventricular tachycardia
• Arrhythmias associated with Ebstien anomaly

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Acquired Conduction System Abnormalities

• Non surgical rare
• Surgical by
• cardioplegia
• mechanical retraction
• ischemia
• metabolic
  abnormalities

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Anaesthetic Risk factors affecting anaesthetic
risk in congenital heart disease
Cyanotic heart disease
Pulmonary disease
Myocardial dysfunction
Cardiovascular impairment
Arrhythmias
Magnitude of surgery
Anaesthetic risk
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How To Reduce Anaesthetic Risk ??
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Consultation
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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. )

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Role Of Pediatric Cardiologist
Preoperative consultation sometimes add a little
benefit to anesthiologist !!!!!
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Efficacy Of Repairs For CHD Lesions
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How To Look To Patient Data
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History Taking

• Growth
• Exercise Intolerance
• Recurrent Chest Infection
• Syncopal Attacks
• Squatting

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ECG , Echo Cardiac Cath.
Systolic Diastolic Dysfunction
Systolic Dysfunction
Reduced Fractional Shortening
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Diastolic Dysfunction
Ventricular Hypertrophy
Concentric
Eccentric
Obstructive
Volume
Before Repair e.g valvular outflow obst.
After Repair e.g Homograft conduit
Before Repair e.g Lt . to Rt. shunt

• After Repair
• e.g
• Pulmonary valve regurge
• ( F4 )
• MV repair

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Anaesthetic considerations
Consider determinants of coronary perfusion
myocardial oxygen balance

• Heart rate changes
• Hypotension
• Myocardial contractility

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Anaesthetic considerations
CONCENTRIC Ventricular Hypertrophy
RV
LV
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• Residual Shunts
• Occasionally present after repair of ASD , VSD
  F4
• Small patch leaks are hemodynamically benign

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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

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• 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

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Pulmonary hypertension
Severity of hypertension of base line PAH
correlated with the incidence of major
complications ( pulmonary hypertensive crisis or
cardiac arrest )
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Cardiovascular risk of PAH

• Major perioperative hemodynamic deterioration
  mainly pulmonary hypertensive crisis and acute
  right ventricular failure and cardiac arrest .
• Data to look for
• Mean pulmonary artery pressure gt 25 mmHg
• Severity of base line PH
• Subsystemic PAP lt 70 of syst. bl.
  pressure
• Systemic PAP 70 100 of syst. bl.
  pressure
• Suprasystemic PAP gt 70 of syst. bl.
  pressure
• ( based on mean pressures )
  

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ANAESTHETIC CONSIDERATIONS Avoid Factors
Rapidly Increasing PVR
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Laboratory data Hematocrit value
Increase More Blood Viscocity
Hyperviscosity symptoms
Decreased oxygen delivery
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Blood Indicies
Increase Blood Viscosity
Hyperviscosity Symptoms At Lower Hematocrit Value
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Phlebotomy Done to relieve hyperviscosity
symptoms with hematocrit gt 65 in absence of
iron deficiency anaemia or signs of dehydration
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• Hemostatic values
• Prolonged PT , PTT , APTT values most frequently
  seen in cyanotic patients
• Thrombocytopenia is related to degree of
  polycythemia .

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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

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Summary Risk criteria of hemodynamic critical
impairment in perioperative period in CHD

• Arterial saturation lt 75
• Hematocrit gt 65
• Qp / Qs gt 2 1
• LV outflow tract gradient gt 50 mmHg
• RVOT gradient gt 50 mmHg
• PVR gt 6 wood units

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THANK YOU