Pathophysiologic Pathophysiologic Consideration Consideration

In Patients With In Patients With Congenital Heart Congenital Heart

DiseaseDisease

Professor Of Anaesthesia .. Ain Shams UniversityProfessor Of Anaesthesia .. Ain Shams University

SAMIA SHARAF .MDSAMIA SHARAF .MD

Classification Of Congenital Heart Classification Of Congenital Heart LesionsLesions

1) Obstructive lesions eg.

Aortic stenosis – coarctation of aorta

1) Increased pulmonary blood flow eg.

ASD – VSD – PDA

1) Decreased pulmonary blood flow lesions eg. Tetralogy of fallot – tricuspid atresia – pulmonary atresia

Classification Of Congenital Heart LesionsClassification 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 StenosisAortic 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 Clinical Presentation Of Children With CHDWith CHD

1) Cyanosis ( due to hypoxia )

2) Respiratory system abnormalities

3) Cardiac failure

4) Arrhythmias

Cyanosis Cyanosis Pathophysiologic Effects of HypoxiaPathophysiologic 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 : PolycythemiaPolycythemia

DICDIC

Primary fibrinoly

sis

Coagulation abnormalities

Mechanism of coagulation abnormalities

Increased blood viscosity

Fibrin depositio

n&

platlet aggreg.

Thrombocytopenia

& Low Fibrinogen & Other

Factor Level

Increase intravasc

ular strains

DIC Hypercoag. blood

& tendency to bleed

Consumpution of

platlets , fibrinogen , factor V ,

VIII

Chronic hypoxia causes impairment of neurologic development and increase risk of neurologic damage .

Brain abscess : Rt. – Lt. shunt Cerebrovascular thrombosis and hemorrhage .

(4) CNS(4) CNS

Respiratiry System AbnormalitiesRespiratiry System Abnormalities

Anatomical abnormalities of airway Pulmonary abnormalities associated with or

pulmonary blood flow .

Anatomical Abnormalities Of Anatomical Abnormalities Of AirwayAirway

1) Short trachea eg. interrupted aortic arch 2) 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 Pulmonary Changes Associated With Pulmonary Blood FlowWith Pulmonary Blood Flow

Patients with chronic hypoxia1) 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 Pulmonary Changes Associated With Pulmonary Blood FlowWith 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 FailureCardiac 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 MechanismCompansatory Mechanism

Ventricular hypertrophy Adrenergic system changes

Activation of B receptors Renal system compansation

*Salt & water retention

*Renin secretion

Types :Types :

* Congenital

* Acquired

Etiology :Etiology : Intrinsic electrophysiology abnormalities Damage from chronic hypoxia – hemodynamic stress Surgical injury eg. F4 , Fontan operation , atrial

correction of TGA

ArrhythmArrhythmiasias

Congenital Conduction System Congenital Conduction System AbnormalitiesAbnormalities

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

Acquired Conduction System Acquired Conduction System AbnormalitiesAbnormalities

Non surgical : rare Surgical by :

* cardioplegia

* mechanical retraction

* ischemia

* metabolic abnormalities

Anaesthetic Risk factors affecting anaesthetic risk in congenital

heart disease

Cyanotic heart Cyanotic heart diseasedisease

Cardiovascular Cardiovascular impairmentimpairment

Pulmonary Pulmonary diseasedisease

Myocardial Myocardial dysfunctiondysfunction

Arrhythmias Arrhythmias

Magnitude Magnitude of surgeryof surgery

Anaesthetic riskAnaesthetic risk

How To Reduce Anaesthetic Risk ??

ConsultatiConsultationon

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 Preoperative consultation sometimes add a little sometimes add a little

benefit to benefit to anesthiologist !!!!!anesthiologist !!!!!

Efficacy Of Repairs For CHD LesionsEfficacy Of Repairs For CHD Lesions

CURED CORRECTION PALLIATION

PDAASD

VSDTFOCoarctation of aortaPulmonary or aortic stenosisAV Canal repair

ConduitsPA bandingModified Glenn shunt

How To Look To Patient Data

History Taking

o Growtho Exercise Intoleranceo Recurrent Chest Infection o Syncopal Attacks o Squatting

ECG , Echo & Cardiac Cath.

Systolic & Diastolic Dysfunction

Reduced Fractional Shortening

Systolic Dysfunction

Diastolic Dysfunction

Ventricular Hypertrophy

Obstructive Volume

Before Repair

e.gvalvular

& outflow

obst.

After Repair

e.g Homograft conduit

Before Repair

e.gLt . to Rt.

shunt

After Repair

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

Concentric Eccentric

Anaesthetic considerations :

Consider determinants of coronary perfusion & myocardial oxygen balance

• Heart rate changes • Hypotension • Myocardial contractility

Anaesthetic considerations

increase wall

thickness

coronary filling become

s diastoli

c

coronary perfusion

depends on bl. p. & hr

Maintain heart rate to

decrease regurgitant

fraction

Syst. DysfunctionIn Dialted

type

RV LVanaesthet

ic myocardia

l depressio

nDecrease driving filling

pressure of coronary arteries

Coronary ischemia

Diast. Dysfunction

In Hypertrophi

c & 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 Arrhythmias Associated With Specific Surgical ProceduresSurgical 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

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

Pulmonary hypertension

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 dataHematocrit value

Increase More Blood ViscocityIncrease More Blood Viscocity

Hyperviscosity Hyperviscosity symptomssymptoms

Decreased oxygen Decreased oxygen deliverydelivery

Blood Indicies :

Increase Blood Increase Blood Viscosity Viscosity

Increase Blood Increase Blood Viscosity Viscosity

Hyperviscosity Symptoms At Hyperviscosity Symptoms At Lower Hematocrit ValueLower Hematocrit Value

Hyperviscosity Symptoms At Hyperviscosity Symptoms At Lower Hematocrit ValueLower 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 .

SummaryGeneral 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

SummaryRisk 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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