Download Infrarenal Aortic Aneurysm

Preparation for Cardiac Surgery
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Evaluation for Congenital HD
• Signs of symptoms of hypoxia
1. Tachypnea & tachycardia
2. Clubbing of the nail bed
3. Small for age from poor feeding
4. Fatigue and poor exercise tolerance
5. Mental obtundation
• Signs & symptoms of congestive heart failure
1. Tachypnea & tachycardia
2. Frequent respiratory infections
3. Wheezing, diffuse rhonchi
4. Feeding difficulty & failure to thrive(small for age)
5. Evidence of peripheral vasoconstriction(pale, cool, mottled)
6. Hepatomegaly, ascites
Preoperative Considerations
Premature Infants
• Lungs; bronchopulmonary dysplasia,
meconium aspiration, pneumothorax
• Heart ; other associated congenital anomalies
• G-I tract ; malrotation, intestinal atresia,
necrotizing enterocolitis
• Hematologic ; Vk deficiency
• Matabolic ; hypoglycemia, hypocalcemia
Preoperative Considerations
Infants under 1 year
• Otitis media
• Upper respiratory infections; RS virus
Toddlers & children
• URI(otitis media, tonsillitis) and G-I
infection(parasites)
• Parental involvement in daily care
Preoperative Considerations
Adult (History)
•
•
•
•
•
•
•
•
•
•
Bleeding issues ; aspirin, warfarin, bleeding disorder
Smoking ; COPD, bronchospasm
Alcohol ; cirrhosis, delirium tremens
Diabetes ; protamine reaction, wound infection
Neurologic symptoms; TIA, stroke, carotid endart.
Vein stripping ; alternative conduits
Ulcer disease/ G-I bleeding
Active infections ; urinary tract
Current medications
Drug allergy
Preoperative Considerations
Adult (Physical Examination)
•
•
•
•
•
•
•
•
Skin infections/rash
Dental caries ; valve surgery
Presence of heart murmur
Vascular examination ; carotid bruits &
peripheral pulse(IABP)
Heart/lung ; congestive heart failure
Differential arm blood pressures
Abdominal aortic aneurysm
Varicose vein ; alternative conduit
Preoperative Diagnosis
•
•
•
•
•
•
•
•
Hematologic
Chemistry
Urinalysis
Chest x-ray
Electrocardiogram
Two-dimensional echocardiography
Cardiac catheterization
CT scan , PET scan, MRI etc
Preoperative Bleeding Issues
• Aspirin irreversibly acetylates platelet cyclooxygenase,
impairing thromboxane A2 formation and inhibiting
platelet aggregation for 7 days, needs to stop for 5-7 days
before surgery.
• Warfarin should be stopped 4 days before surgery.
Consideration may be given to use IV heparin (low-molecular-weight
heparin 3000u sc bid), when INR falls below therapeutic level,
although the risk of thromboembolism is low.
• Bleeding disorders or coagulopathy needs evaluation.
Thrombolytic or antiplatelet medications (ticlopidine, clopidogrel,
glycoprotein IIb/IIIa inhibitors , such as, abcximab (reopro)
tirofiban(aggrastat), or eptifibatide(integrilin), specific measure is
needed. Nonsteridal antiinflammatory drugs have a reversible effect
on platelet function and need to be stopped only a few days.
Preparation for Heart Surgery
• Antibiotics; cefazolin 12.5mg/kg before surgical
incision or vancomycin of same dose in allergic to
cefazolin
• Blood bank
• Most medications are withheld (digoxin, diuretics)
the morning of surgery
• Vk 0.25mg/kg before OHS
• Premedication ; avoid to increase PVR
• Kept NPO after midnight and fluids can be given
about 3~4 hours before surgery to avoid dehydration
States of Congenital Heart Diseases
• Acute conditions of left and/or right ventricular volume or pressure
overload or both may reduce myocardial reserve & high energy
phosphate and impair recovery from periods of ischemia during
cardiac surgery.
1. Acute hypoxia and acidosis
2. Chronic ischemia ; decreased EF, drop high energy phosphate
3. Volume overload ; effects the distensibility of the other,
unfavorable structural & metabolic changes in myocardium
4. Pressure overload ; inefficient O2 use, lower level of high
energy phosphates
5. Noncoronary collateral flow ; washout cardioplegia
Structural Abnormalities of Great Arterial Wall
in Congenital Heart Disease
• Etiology
Inherent, one or more genetic defects?
Independent variables
Pregnancy, age, systemic hypertension influence aortic media
• Grading of Medial Change
Normal ; normal aortic media with closely packed long
parallel arrays of intact elastic fiber
Grade I ; mild elastic fiber fragmentation, patch pale zone in
continuity, & mild increase in collagen
Grade II ; widespread elastic fiber fragmentation & loss of
smooth muscle, further increase in ground substance
Grade III ; large areas of complete loss of elastic fiber & smooth
muscle & abundant collagen
Features of Pediatric Cardiac
Management
•
•
•
•
•
Variable pathology
Compensatory mechanism
Monitoring limitations
Assessment of LCO states
Special studies
Early reinvestigation is indicated
• Acceptable parameters
Neonatal Physiology of Normal
Myocardium
• Decreased compliance of fetal & neonatal
right and left ventricle
• Decreased capacity for peripheral vasodilation
• Decreased capacity for response to volume
loading (diminished preload reservoir)
Predisposition to Postoperative
RV Failure
•
•
•
•
•
•
•
Underdevelopment of RV structure
Chronic high pressure loading (hypertrophy)
Chronic volume overload (dilatation)
Less effective myocardial protection
Right ventriculotomy incision
Interruption of right coronary artery branches
Residual pulmonary stenosis or insufficiency or
tricuspid insufficiency
Factors Affecting Myocardial
Protection of Infant Heart
• Cardiac size
; large surface area to mass ratio
• Collateral circulation ; increased collateral circulation
• Microcirculation ; increased permeability of capillary
membrane to albumin & large molecules --- edema formation
• Traumatic myocardial injury ; excision, cardiotomy
• Pathologic states of myocardium ; cyanosis, congestive
heart failure, hypertrophy,
Assessment of RV Function
• Clinical signs of RV failure
Jugular venous distention
Hepatomegaly
Peripheral e4dema
Ascites
Periorbital, flank, and generalized edema
Rising BUN
• Elevated RA pressure with low LA pressure
Volume loading, often to an RA pressure of 15mmHg
or greater, may be necessary to ensure adequate
left-sided filling
Fluid & Electrolyte Requirement
• Fluid volume
a. Daily fluid requirement is 4ml/kg/h for the first
10kg, 2ml/kg/h for the next 10kg, and 1ml/kg/h
for each subsequent kg.
b. Intubated patients are given two-thirds of
maintenance of level (due to water gain)
• Eletrolytes
a. Sodium; 3mEq/100ml/d
b. Potassium; 2-3mEq/100ml/d
Physiology of Coronary Artery
• Proximal epicardial vessel
Richly innervated by sympathetic alpha & beta
fiber(alpha; proximal, beta; distal) -- cause spasm
• Distal intramyocardial vessel
Little autonomic innervation, less smooth muscle, do
not constrict markedly, but do dilate to the metabolic
demand -- cause little spasm
• Spasm is common in RCA & LAD,
especially in underlying obstruction
Arterial Blood Pressure
• Determinants of systolic blood pressure
1. Volume of blood ejected
2. Compliance of arterial wall
3. Rate of run-off (resistance)
• Determinants of diastolic blood pressure
1. Volume of blood remained
2. Compliance of arterial wall
3. Peripheral resistance
Venous Blood Pressure
• Determinants of venous pressure
1. Blood volume
2. Pressure-volume characteristics of venous bed
(compliance)
3. Size of venous bed (capacitance)
4. Ability of heart to eject venous return
• Location of venous blood volume
1. Peripheral vein ; 65%
2. Pulmonary venous system ; 5%
Cardiac Receptors
• Atrial receptors
Located mainly pulmonary venous and caval-atrial junction, others
on the body of left & right atrium, appendage connected to the
myelinated fiber of Vagus nerve.
Not related BT, PVR, myocardial contractility
1. Type A ; atrial contraction for pressure ( a wave )
2. Type B ; stretch receptor for volume ( v wave )
• Ventricular receptors
Myelinated & unmyelinated, but uncertain function
Ventricular reflexes – LV distention cause reflex vasodepression
Arterial Baroreceptors
1. Anatomic location
Carotid sinus ;
segmental enlargement of internal carotid
artery at it’s origin, (stimulation; drop BP in 23% & 14% of SVR,
low carotid sinus pressure; vasoconstriction, increase CO in 30%)
Aortic arch ; located in the adventitia adjacent to media
between brachiocephalic trunk and ligament arteriosum
2. Transmission
Afferent impulse ;
generated by stretch of arterial walls and
transmitted myelinated & nonmyelinated sensory fiber of carotid
sinus nerve travel glossopharyngeal nerve
No distant pathway of aortic arch stretch receptor
Efferent impulse ; consist of sympathetic adrenergic nerves
to heart, vessel
Low Cardiac Output Syndrome
• Diagnosis
a. Suspicion of LCO by evidence of peripheral vasoconstriction
( cool, pale extremities, mottling, absence of pedal pulses, and
capillary refill exceeding 3 seconds), oliguria, metabolic acidosis,
and hyperthermia.
b. Narrow arterial pulse, elevated filling pressure, low RA oxygen
saturation, development of atrial or ventricular arrhythmias,
should draw attention to a LCO
• Treatment
a. Assessment and manipulation of heart rate, and rhythm, volume
state, contractility, and afterload.
b. Additional contributory factors should be identified
Cardiac temponade, ventilator problems, metabolic problems
Cardiac Surgery during Pregnancy
 Measures to reduce maternal & fetal mortality
• Avoid functional deterioration during pregnancy
• Prescribe earlier surgery to prevent these patients from
requiring an emergency procedure
• Perform surgery as fast as possible, with minimal ECC
• Provide adequate fetal monitoring (cardiotachometer &
intraoperative fetal echocardiography)
• Perform surgery in the second trimester of pregnancy
preferably
Preparation for Cardiac Surgery
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Evaluation for Congenital HD
• Signs of symptoms of hypoxia
1. Tachypnea & tachycardia
2. Clubbing of the nail bed
3. Small for age from poor feeding
4. Fatigue and poor exercise tolerance
5. Mental obtundation
• Signs & symptoms of congestive heart failure
1. Tachypnea & tachycardia
2. Frequent respiratory infections
3. Wheezing, diffuse rhonchi
4. Feeding difficulty & failure to thrive(small for age)
5. Evidence of peripheral vasoconstriction(pale, cool, mottled)
6. Hepatomegaly, ascites
Preoperative Considerations in
Premature Infants
• Lungs; bronchopulmonary dysplasia,
meconium aspiration, pneumothorax
• Heart ; other associated congenital
anomalies
• G-I tract ; malrotation, intestinal atresia,
necrotizing enterocolitis
• Hematologic ; Vk deficiency
• Matabolic ; hypoglycemia, hypocalcemia
Preoperative Considerations in
Infants & Child
Infants under 1 year
• Otitis media
• Upper respiratory infections; RS virus
Toddlers & children
• URI(otitis media, tonsillitis) and G-I
infection(parasites)
• Parental involvement in daily care
Preoperative Considerations in
Adult (History)
•
•
•
•
•
•
•
•
•
Bleeding issues ; aspirin, warfarin, bleeding disorder
Smoking ; COPD, bronchospasm
Alcohol ; cirrhosis, delirium tremens
Diabetes ; protamine reaction, wound infection
Neurologic symptoms; TIA, remote stroke, carotid endart.
Vein stripping ; alternative conduits
Ulcer disease/ G-I bleeding
Active infections ; urinary tract
Current medications & drug allergy
Preoperative Considerations in
Adult (Physical Examination)
•
•
•
•
•
•
•
•
Skin infections/rash
Dental caries ; valve surgery
Presence of heart murmur
Vascular examination ; carotid bruits &
peripheral pulse(IABP)
Heart/lung ; congestive heart failure
Differential arm blood pressures
Abdominal aortic aneurysm
Varicose vein ; alternative conduit
Preoperative Diagnostic Studies
•
•
•
•
•
•
•
•
Hematologic
Chemistry
Urinalysis
Chest x-ray
Electrocardiogram
Two-dimensional echocardiography
Cardiac catheterization
CT scan , PET scan, MRI etc
Preoperative Bleeding Issues
• Aspirin irreversibly acetylates platelet cyclooxygenase,
impairing thromboxane A2 formation and inhibiting
platelet aggregation for 7 days, needs to stop for 5-7 days
before surgery.
• Warfarin should be stopped 4 days before surgery.
Consideration may be given to use IV heparin (low-molecular-weight
heparin 3000u sc bid), when INR falls below therapeutic level,
although the risk of thromboembolism is low.
• Bleeding disorders or coagulopathy needs evaluation.
Thrombolytic or antiplatelet medications (ticlopidine, clopidogrel,
glycoprotein IIb/IIIa inhibitors , such as, abcximab (reopro)
tirofiban(aggrastat), or eptifibatide(integrilin), specific measure is
needed. Nonsteridal antiinflammatory drugs have a reversible effect
on platelet function and need to be stopped only a few days.
Preparation for Heart Surgery
• Antibiotics; cefazolin 12.5mg/kg before surgical
incision or vancomycin of same dose in allergic to
cefazolin
• Blood bank
• Most medications are withheld (digoxin, diuretics)
the morning of surgery
• Vk 0.25mg/kg before OHS
• Premedication ; avoid to increase PVR
• Kept NPO after midnight and fluids can be given
about 3~4 hours before surgery to avoid
dehydration
States of Congenital Heart D.
• Acute conditions of left and/or right ventricular volume or pressure
overload or both may reduce myocardial reserve & high energy
phosphate and impair recovery from periods of ischemia during
cardiac surgery.
1. Acute hypoxia and acidosis
2. Chronic ischemia ; decreased EF, drop high energy phosphate
3. Volume overload ; effects the distensibility of the other,
unfavorable structural & metabolic changes in myocardium
4. Pressure overload ; inefficient O2 use, lower level of high
energy phosphates
5. Noncoronary collateral flow ; washout cardioplegia
Abnormalities of Great Arterial Wall
in Congenital Heart Disease
• Etiology
Inherent, one or more genetic defects?
Independent variables
Pregnancy, age, systemic hypertension influence aortic media
• Grading of Medial Change
Normal ; normal aortic media with closely packed long
parallel arrays of intact elastic fiber
Grade I ; mild elastic fiber fragmentation, patch pale zone in
continuity, & mild increase in collagen
Grade II ; widespread elastic fiber fragmentation & loss of
smooth muscle, further increase in ground substance
Grade III ; large areas of complete loss of elastic fiber & smooth
muscle & abundant collagen
Features of Pediatric Cardiac
Management
•
•
•
•
•
Variable pathology
Compensatory mechanism
Monitoring limitations
Assessment of LCO states
Special studies
Early reinvestigation is indicated
• Acceptable parameters
Neonatal Physiology of Normal
Myocardium
• Decreased compliance of fetal & neonatal
right and left ventricle
• Decreased capacity for peripheral vasodilation
• Decreased capacity for response to volume
loading (diminished preload reservoir)
Predisposition to Postoperative
RV Failure
•
•
•
•
•
•
•
Underdevelopment of RV structure
Chronic high pressure loading (hypertrophy)
Chronic volume overload (dilatation)
Less effective myocardial protection
Right ventriculotomy incision
Interruption of right coronary artery branches
Residual pulmonary stenosis or insufficiency or
tricuspid insufficiency
Factors Affecting Myocardial
Protection of Infant Heart
• Cardiac size
; large surface area to mass ratio
• Collateral circulation ; increased collateral circulation
• Microcirculation ; increased permeability of capillary
membrane to albumin & large molecules --- edema formation
• Traumatic myocardial injury ; excision, cardiotomy
• Pathologic states of myocardium ; cyanosis, congestive
heart failure, hypertrophy,
Assessment of RV Function
• Clinical signs of RV failure
Jugular venous distention
Hepatomegaly
Peripheral e4dema
Ascites
Periorbital, flank, and generalized edema
Rising BUN
• Elevated RA pressure with low LA pressure
Volume loading, often to an RA pressure of 15mmHg
or greater, may be necessary to ensure adequate
left-sided filling
Fluid & Electrolyte Requirement
• Fluid volume
a. Daily fluid requirement is 4ml/kg/h for the first
10kg, 2ml/kg/h for the next 10kg, and 1ml/kg/h
for each subsequent kg.
b. Intubated patients are given two-thirds of
maintenance of level (due to water gain)
• Eletrolytes
a. Sodium; 3mEq/100ml/d
b. Potassium; 2-3mEq/100ml/d
Physiology of Coronary Artery
• Proximal epicardial vessel
Richly innervated by sympathetic alpha & beta
fiber(alpha; proximal, beta; distal) -- cause spasm
• Distal intramyocardial vessel
Little autonomic innervation, less smooth muscle, do
not constrict markedly, but do dilate to the metabolic
demand -- cause little spasm
• Spasm is common in RCA & LAD,
especially in underlying obstruction
Arterial Blood Pressure
• Determinants of systolic blood pressure
1. Volume of blood ejected
2. Compliance of arterial wall
3. Rate of run-off (resistance)
• Determinants of diastolic blood pressure
1. Volume of blood remained
2. Compliance of arterial wall
3. Peripheral resistance
Venous Blood Pressure
• Determinants of venous pressure
1. Blood volume
2. Pressure-volume characteristics of venous bed
(compliance)
3. Size of venous bed (capacitance)
4. Ability of heart to eject venous return
• Location of venous blood volume
1. Peripheral vein ; 65%
2. Pulmonary venous system ; 5%
Cardiac Receptors
• Atrial receptors
Located mainly pulmonary venous and caval-atrial junction, others
on the body of left & right atrium, appendage connected to the
myelinated fiber of Vagus nerve.
Not related BT, PVR, myocardial contractility
1. Type A ; atrial contraction for pressure ( a wave )
2. Type B ; stretch receptor for volume ( v wave )
• Ventricular receptors
Myelinated & unmyelinated, but uncertain function
Ventricular reflexes – LV distention cause reflex vasodepression
Arterial Baroreceptors
1. Anatomic location
Carotid sinus ;
segmental enlargement of internal carotid
artery at it’s origin, (stimulation; drop BP in 23% & 14% of SVR,
low carotid sinus pressure; vasoconstriction, increase CO in 30%)
Aortic arch ; located in the adventitia adjacent to media
between brachiocephalic trunk and ligament arteriosum
2. Transmission
Afferent impulse ;
generated by stretch of arterial walls and
transmitted myelinated & nonmyelinated sensory fiber of carotid
sinus nerve travel glossopharyngeal nerve
No distant pathway of aortic arch stretch receptor
Efferent impulse ; consist of sympathetic adrenergic nerves
to heart, vessel
Low Cardiac Output Syndrome
• Diagnosis
a. Suspicion of LCO by evidence of peripheral vasoconstriction
( cool, pale extremities, mottling, absence of pedal pulses, and
capillary refill exceeding 3 seconds), oliguria, metabolic acidosis,
and hyperthermia.
b. Narrow arterial pulse, elevated filling pressure, low RA oxygen
saturation, development of atrial or ventricular arrhythmias,
should draw attention to a LCO
• Treatment
a. Assessment and manipulation of heart rate, and rhythm, volume
state, contractility, and afterload.
b. Additional contributory factors should be identified
Cardiac temponade, ventilator problems, metabolic problems
Re-Operative Surgery in
Pediatric Patients
• Re-do sternotomy
Anatomic considerations
Planning
Technique
• Alternative cannulation sites
• Pericardial substitutes
Infection
Tamponade
Epicardial reaction
• Aprotinin
Hypersensitivity (or adverse reaction ; 3%)
Histamin blocker
Anatomic considerations in Re-do
Sternotomy
•
•
•
•
Substernal homografts or conduit
Degenerated homografts
Enlarged right ventricle due to PR or TR
Dilated right atrium due to TR or Ebstein’s
anomaly or atrio-pulmonary connection
• Presence of pseudoaneurysm
Planning & Techniques in Re-Do
• Techniques of re-do sternotomy
1. Head facing to the left
2. Provide gentle cervical extension
3. Cutaneous defibrillation patches
4. Incision rather than excise the previous incision
5. Incision carried inferiorly 1-3cm below previous incision
6. Division of the adhesions immediately below the sternum
• Alternative cannulation sites ; femoral vessels are often of an
inadequate, particularly in pre-toddler patients, consequently
cervical (common carotid a, internal jugular vein) cannulation is
prefered
• Pericardial substitutes
PTFE membrane, bovine pericardium, polyglycolic acid mesh,
hyaluronic acid, poly-beta-hydroxybutyrate(PHB), glutaldehydechitosan treated porcine pericardium, epoxy fixed porcine
pericardium
Cardiac Surgery during Pregnancy
 Measures to reduce maternal & fetal mortality
• Avoid functional deterioration during pregnancy
• Prescribe earlier surgery to prevent these patients from
requiring an emergency procedure
• Perform surgery as fast as possible, with minimal ECC
• Provide adequate fetal monitoring (cardiotachometer &
intraoperative fetal echocardiography)
• Perform surgery in the second trimester of pregnancy
preferably
Cardiac Surgery during Pregnancy
 Measures to reduce maternal & fetal risks
• Extracorporeal circulation with high flow, high
pressures (mean blood pressure of 60 mm Hg),
and normothermia should be used
• Hyperoxygenation should be maintained and
hematocrit should be kept higher than 25%
• Myocardial protection using intermittent
clamping allows, during normothermia, short
perfusion times with pulsatile flow, which
favors the fetus
Ideal Gestational Age for Operation
• Period between the 13th and 28th weeks as ideal
• Higher trend towards fetal malformations in the
first trimester.
• Higher trend towards preterm delivery,
maternal hemodynamic alterations, and
mortality in the third
• There was no relationship between maternal and
fetal outcome and surgical indication according
to gestational age
• Fetal mortality is described as higher than 50%
in patients in functional class III and IV
Preparation for Cardiac Surgery
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Evaluation for Congenital HD
• Signs of symptoms of hypoxia
1. Tachypnea & tachycardia
2. Clubbing of the nail bed
3. Small for age from poor feeding
4. Fatigue and poor exercise tolerance
5. Mental obtundation
• Signs & symptoms of congestive heart failure
1. Tachypnea & tachycardia
2. Frequent respiratory infections
3. Wheezing, diffuse rhonchi
4. Feeding difficulty & failure to thrive(small for age)
5. Evidence of peripheral vasoconstriction(pale, cool, mottled)
6. Hepatomegaly, ascites
Preoperative Considerations in
Premature Infants
• Lungs; bronchopulmonary dysplasia,
meconium aspiration, pneumothorax
• Heart ; other associated congenital
anomalies
• G-I tract ; malrotation, intestinal atresia,
necrotizing enterocolitis
• Hematologic ; Vk deficiency
• Matabolic ; hypoglycemia, hypocalcemia
Preoperative Considerations in
Infants & Child
Infants under 1 year
• Otitis media
• Upper respiratory infections; RS virus
Toddlers & children
• URI(otitis media, tonsillitis) and G-I
infection(parasites)
• Parental involvement in daily care
Preoperative Considerations in
Adult (History)
•
•
•
•
•
•
•
•
•
Bleeding issues ; aspirin, warfarin, bleeding disorder
Smoking ; COPD, bronchospasm
Alcohol ; cirrhosis, delirium tremens
Diabetes ; protamine reaction, wound infection
Neurologic symptoms; TIA, remote stroke, carotid endart.
Vein stripping ; alternative conduits
Ulcer disease/ G-I bleeding
Active infections ; urinary tract
Current medications & drug allergy
Preoperative Considerations in
Adult (Physical Examination)
•
•
•
•
•
•
•
•
Skin infections/rash
Dental caries ; valve surgery
Presence of heart murmur
Vascular examination ; carotid bruits &
peripheral pulse(IABP)
Heart/lung ; congestive heart failure
Differential arm blood pressures
Abdominal aortic aneurysm
Varicose vein ; alternative conduit
Preoperative Diagnostic Studies
•
•
•
•
•
•
•
•
Hematologic
Chemistry
Urinalysis
Chest x-ray
Electrocardiogram
Two-dimensional echocardiography
Cardiac catheterization
CT scan , PET scan, MRI etc
Preoperative Bleeding Issues
• Aspirin irreversibly acetylates platelet cyclooxygenase,
impairing thromboxane A2 formation and inhibiting
platelet aggregation for 7 days, needs to stop for 5-7 days
before surgery.
• Warfarin should be stopped 4 days before surgery.
Consideration may be given to use IV heparin (low-molecular-weight
heparin 3000u sc bid), when INR falls below therapeutic level,
although the risk of thromboembolism is low.
• Bleeding disorders or coagulopathy needs evaluation.
Thrombolytic or antiplatelet medications (ticlopidine, clopidogrel,
glycoprotein IIb/IIIa inhibitors , such as, abcximab (reopro)
tirofiban(aggrastat), or eptifibatide(integrilin), specific measure is
needed. Nonsteridal antiinflammatory drugs have a reversible effect
on platelet function and need to be stopped only a few days.
Preparation for Heart Surgery
• Antibiotics; cefazolin 12.5mg/kg before surgical
incision or vancomycin of same dose in allergic to
cefazolin
• Blood bank
• Most medications are withheld (digoxin, diuretics)
the morning of surgery
• Vk 0.25mg/kg before OHS
• Premedication ; avoid to increase PVR
• Kept NPO after midnight and fluids can be given
about 3~4 hours before surgery to avoid
dehydration
States of Congenital Heart D.
• Acute conditions of left and/or right ventricular volume or pressure
overload or both may reduce myocardial reserve & high energy
phosphate and impair recovery from periods of ischemia during
cardiac surgery.
1. Acute hypoxia and acidosis
2. Chronic ischemia ; decreased EF, drop high energy phosphate
3. Volume overload ; effects the distensibility of the other,
unfavorable structural & metabolic changes in myocardium
4. Pressure overload ; inefficient O2 use, lower level of high
energy phosphates
5. Noncoronary collateral flow ; washout cardioplegia
Abnormalities of Great Arterial Wall
in Congenital Heart Disease
• Etiology
Inherent, one or more genetic defects?
Independent variables
Pregnancy, age, systemic hypertension influence aortic media
• Grading of Medial Change
Normal ; normal aortic media with closely packed long
parallel arrays of intact elastic fiber
Grade I ; mild elastic fiber fragmentation, patch pale zone in
continuity, & mild increase in collagen
Grade II ; widespread elastic fiber fragmentation & loss of
smooth muscle, further increase in ground substance
Grade III ; large areas of complete loss of elastic fiber & smooth
muscle & abundant collagen
Features of Pediatric Cardiac
Management
•
•
•
•
•
Variable pathology
Compensatory mechanism
Monitoring limitations
Assessment of LCO states
Special studies
Early reinvestigation is indicated
• Acceptable parameters
Neonatal Physiology of Normal
Myocardium
• Decreased compliance of fetal & neonatal
right and left ventricle
• Decreased capacity for peripheral vasodilation
• Decreased capacity for response to volume
loading (diminished preload reservoir)
Predisposition to Postoperative
RV Failure
•
•
•
•
•
•
•
Underdevelopment of RV structure
Chronic high pressure loading (hypertrophy)
Chronic volume overload (dilatation)
Less effective myocardial protection
Right ventriculotomy incision
Interruption of right coronary artery branches
Residual pulmonary stenosis or insufficiency or
tricuspid insufficiency
Factors Affecting Myocardial
Protection of Infant Heart
• Cardiac size
; large surface area to mass ratio
• Collateral circulation ; increased collateral circulation
• Microcirculation ; increased permeability of capillary
membrane to albumin & large molecules --- edema formation
• Traumatic myocardial injury ; excision, cardiotomy
• Pathologic states of myocardium ; cyanosis, congestive
heart failure, hypertrophy,
Assessment of RV Function
• Clinical signs of RV failure
Jugular venous distention
Hepatomegaly
Peripheral e4dema
Ascites
Periorbital, flank, and generalized edema
Rising BUN
• Elevated RA pressure with low LA pressure
Volume loading, often to an RA pressure of 15mmHg
or greater, may be necessary to ensure adequate
left-sided filling
Fluid & Electrolyte Requirement
• Fluid volume
a. Daily fluid requirement is 4ml/kg/h for the first
10kg, 2ml/kg/h for the next 10kg, and 1ml/kg/h
for each subsequent kg.
b. Intubated patients are given two-thirds of
maintenance of level (due to water gain)
• Eletrolytes
a. Sodium; 3mEq/100ml/d
b. Potassium; 2-3mEq/100ml/d
Physiology of Coronary Artery
• Proximal epicardial vessel
Richly innervated by sympathetic alpha & beta
fiber(alpha; proximal, beta; distal) -- cause spasm
• Distal intramyocardial vessel
Little autonomic innervation, less smooth muscle, do
not constrict markedly, but do dilate to the metabolic
demand -- cause little spasm
• Spasm is common in RCA & LAD,
especially in underlying obstruction
Arterial Blood Pressure
• Determinants of systolic blood pressure
1. Volume of blood ejected
2. Compliance of arterial wall
3. Rate of run-off (resistance)
• Determinants of diastolic blood pressure
1. Volume of blood remained
2. Compliance of arterial wall
3. Peripheral resistance
Venous Blood Pressure
• Determinants of venous pressure
1. Blood volume
2. Pressure-volume characteristics of venous bed
(compliance)
3. Size of venous bed (capacitance)
4. Ability of heart to eject venous return
• Location of venous blood volume
1. Peripheral vein ; 65%
2. Pulmonary venous system ; 5%
Cardiac Receptors
• Atrial receptors
Located mainly pulmonary venous and caval-atrial junction, others
on the body of left & right atrium, appendage connected to the
myelinated fiber of Vagus nerve.
Not related BT, PVR, myocardial contractility
1. Type A ; atrial contraction for pressure ( a wave )
2. Type B ; stretch receptor for volume ( v wave )
• Ventricular receptors
Myelinated & unmyelinated, but uncertain function
Ventricular reflexes – LV distention cause reflex vasodepression
Arterial Baroreceptors
1. Anatomic location
Carotid sinus ;
segmental enlargement of internal carotid
artery at it’s origin, (stimulation; drop BP in 23% & 14% of SVR,
low carotid sinus pressure; vasoconstriction, increase CO in 30%)
Aortic arch ; located in the adventitia adjacent to media
between brachiocephalic trunk and ligament arteriosum
2. Transmission
Afferent impulse ;
generated by stretch of arterial walls and
transmitted myelinated & nonmyelinated sensory fiber of carotid
sinus nerve travel glossopharyngeal nerve
No distant pathway of aortic arch stretch receptor
Efferent impulse ; consist of sympathetic adrenergic nerves
to heart, vessel
Low Cardiac Output Syndrome
• Diagnosis
a. Suspicion of LCO by evidence of peripheral vasoconstriction
( cool, pale extremities, mottling, absence of pedal pulses, and
capillary refill exceeding 3 seconds), oliguria, metabolic acidosis,
and hyperthermia.
b. Narrow arterial pulse, elevated filling pressure, low RA oxygen
saturation, development of atrial or ventricular arrhythmias,
should draw attention to a LCO
• Treatment
a. Assessment and manipulation of heart rate, and rhythm, volume
state, contractility, and afterload.
b. Additional contributory factors should be identified
Cardiac temponade, ventilator problems, metabolic problems
Re-Operative Surgery in
Pediatric Patients
• Re-do sternotomy
Anatomic considerations
Planning
Technique
• Alternative cannulation sites
• Pericardial substitutes
Infection
Tamponade
Epicardial reaction
• Aprotinin
Hypersensitivity (or adverse reaction ; 3%)
Histamin blocker
Anatomic considerations in Re-do
Sternotomy
•
•
•
•
Substernal homografts or conduit
Degenerated homografts
Enlarged right ventricle due to PR or TR
Dilated right atrium due to TR or Ebstein’s
anomaly or atrio-pulmonary connection
• Presence of pseudoaneurysm
Planning & Techniques in Re-Do
• Techniques of re-do sternotomy
1. Head facing to the left
2. Provide gentle cervical extension
3. Cutaneous defibrillation patches
4. Incision rather than excise the previous incision
5. Incision carried inferiorly 1-3cm below previous incision
6. Division of the adhesions immediately below the sternum
• Alternative cannulation sites ; femoral vessels are often of an
inadequate, particularly in pre-toddler patients, consequently
cervical (common carotid a, internal jugular vein) cannulation is
prefered
• Pericardial substitutes
PTFE membrane, bovine pericardium, polyglycolic acid mesh,
hyaluronic acid, poly-beta-hydroxybutyrate(PHB), glutaldehydechitosan treated porcine pericardium, epoxy fixed porcine
pericardium
Cardiac Surgery during Pregnancy
 Measures to reduce maternal & fetal mortality
• Avoid functional deterioration during pregnancy
• Prescribe earlier surgery to prevent these patients from
requiring an emergency procedure
• Perform surgery as fast as possible, with minimal ECC
• Provide adequate fetal monitoring (cardiotachometer &
intraoperative fetal echocardiography)
• Perform surgery in the second trimester of pregnancy
preferably
Cardiac Surgery during Pregnancy
 Measures to reduce maternal & fetal risks
• Extracorporeal circulation with high flow, high
pressures (mean blood pressure of 60 mm Hg),
and normothermia should be used
• Hyperoxygenation should be maintained and
hematocrit should be kept higher than 25%
• Myocardial protection using intermittent
clamping allows, during normothermia, short
perfusion times with pulsatile flow, which
favors the fetus
Ideal Gestational Age for Operation
• Period between the 13th and 28th weeks as ideal
• Higher trend towards fetal malformations in the
first trimester.
• Higher trend towards preterm delivery,
maternal hemodynamic alterations, and
mortality in the third
• There was no relationship between maternal and
fetal outcome and surgical indication according
to gestational age
• Fetal mortality is described as higher than 50%
in patients in functional class III and IV