cyanotic spell
TRANSCRIPT
MANAGEMENT OF CYANOTIC PATIENT
Dr. I.Tammi Raju
Management of Cyanotic Patients
• Causes of cyanosis-non cardiac • Medical
– cyanotic spell– Hematologic derangements– Hyperviscosity symptoms– Bleeding diatheses– Neurological complications– Renal complications– Hyperuricemia
• Surgical– Palliative– definitive
Non-Cardiac Causes of Newborn Cyanosis
• Primary lung disease• RDS, pneumonia, hypoplasia, CCAM, lymphangectasia,
lobar• Emphysema
• Mechanical interference with lung function• Congenital diaphragmatic hernia, pneumothorax,
pneumomediastinum, chylothorax, choanal atresia, vascular ring, tracheal esophageal atresia, anomalies of the airway/larynx, Pierre-Robin/ micrognathia
• Pulmonary hypertension• Meconium aspiration, pneumothorax, RDS, sepsis,
pneumonia
• CENTRAL NERVOUS SYSTEMSeizure, meningitis, encephalitis, severe IVH, subdural or subarachnoid hemorrhage,
• Severe hypermagnesemia• Shock• Sepsis, hypovolemia, adrenal crisis• Severe hypoglycemia (IDM, SGA babies)• Congenital neuromuscular condition (Werdnig-
Hoffman)• - METHEMOGLOBINEMIA
Evaluation of the Cyanotic Neonate
• Detecting cyanosis:– ambient lighting– skin color – hemoglobin
if Hg is 20 gm/dl; 4 gm desaturated-visible cyanosisif Hg is 10 gm/dl; 2 gm desaturated-not cyanotic
• Check Saturation
• Hyperoxia Test to Determine Intrapulmonary vs. Intracardiac Shunt
Hyperoxia Test
1. On room air (if tolerated)-measure pO2 by blood gas
2. On 100% FIO2 - blow-by, mask, ETT-repeat measurement of pO2
DANGERS: Pulmonary overcirculationClosing the PDA
Hyperoxia Test - Interpretation
• pO2 < 100; cyanotic CHD likely
• pO2 100-150; cyanotic CHD possible
• pO2 > 150; cyanotic CHD unlikely
CYANOTIC SPELL
Also called as Hyperpnoeic spell, Hypoxic spell, Anoxic or blue spell or Tet spell.
Occurs in cyanotic congenital heart diseases with reduced Pulm. Blood flow.
A pediatric emergency- a typical episode can lead to death.
Peak incidence between the age group of 2-6 months.
Episodes beyond the age of 2 years are rare. About 40% of pts. With cyanotic congenital heart
disease & decreased blood flow, develop this spell.
Cyanotic spell (Contd.)
A typical episode begins with a progressive increase in rate & depth of respiration, resulting in paroxysmal hyperpnoea,deepening cyanosis, limpness & syncope, convulsions, CVA & even death.
The spells are usually self-limited and last for about <15-30 mins. duration.
CYANOTIC SPELLCYANOTIC SPELL (CONTD.)
During the spell, the Ejection Systolic Murmur (ESM) which is heard along the left sternal border due to the Infundibular Stenosis, may disappear.
The ECG may show an increased amplitude of P wave along with ST-T segment depression.
• CYANOTIC SPELLS are classically described in ;-
-- Tetrology of Fallot-- DORV With VSD with PS-- Tricuspid Atresia-- Single Ventricle with Pulm. Stenosis-- Transposition of great arteries.-- Eisenmenger’s Syndrome
Mechanisms of Cyanotic Spell1. Increased vulnerability of respiratory Centre ;-
- When a child awakes from a deep & prolonged sleep a stress occurs due to crying feeding or bowel movement.
- Any increase in activity or Valsalva like maneuver leads to increased H/R, increased cardiac o/p and increased venous return, while there is a fixed obstruction to RVOT.
- Increased cardiac o/p results in a decrease in SVR by about 20% while BP remains constant (BP=CO x SVR).
- The increased venous return passes from RV to LV in view of reduced SVR.
Vulnerability of Resp. centre (contd.)
- GUNTHER et al As R to L shunt increases, the already low pulm.
Blood flow further declines and the cyanosis deepens.
- Desaturated blood entering the systemic circulation causes the overreaction of resp. centre to chemical stimuli resulting in hyperpnoea.
- Hyperpnoea further increases the CO and perpetuates the vicious cycle.
- Also, the Vena Cavae have a pumping effect on the blood flow with respiration.
- This effect gets exaggerated in c/o reduced pulm. Blood flow and RVOT obstruction.
2. Infundibular Spasm - Activities which increases
the catecholamine secretions (feeding, crying, bowel movement, effort, breath holding, infection, cardiac catheterization), precipitate the Cyanotic Spell.
- The elevated NE levels may provoke RV Infundibular narrowing, thus compromising the pulm. blood flow and precipitating the spasm.
3.SVT- paroxysmal Supraventricular Tachy. or rapid atrial pacing results in decreased RV volume and increase in R to L shunt → a fall in systemic arterial O2 saturation and an increase in RV outflow obstruction → precipitation of Cyanotic Spell.
- This is not a widely accepted mechanism.
4. MET. ACIDOSIS – occurs in the setting of extremely limited pulm. Blood flow.
- It is secondary to anaerobic metabolism. - Since the arterial pO2 is below level, there will be a
consistent Lactate accumulation. - However this mechanism can-not explain the
paroxysmal nature of the spell.
Mechanisms responsible for the rare occurrence of the spell after the age of 2 years could be ;-
The child learns to squat by habit as soon as he feels breathless.
The respiratory centre matures by this age.
Development of the collaterals.
Fibrosis of the Infundibulum prevents it developing a spasm.
• Incresed SVR(kinking of major arterial circulation)- in presence of fixed pulmonary outflow resistance
• Decreased Rt to Lt flow & more of RV blood into PA-
• increased oxygenated blood to LV-
• decreased CO2 –decreased stimulation of respiratory center-
• decreased hyperventilation.
SQUATTING
• Decreased SV return
• decreased desaturated blood from lower limbs to heart-
• increased oxygenated RV blood will be shunted to LV
• This shunted blood have high PH & O2,low CO2.
MANAGEMENT OF CYANOTIC SPELL
A. Other possible mechanisms ;- Weight/volume of blood below the heart distends
the arterial bed in upright posture.
Squatting removes this distending force and narrows the arterial bed.
A small and immediate rise in arterial resistance and BP develops with accompanying bradycardia.
Bradycardia in turn breaks the vicious cycle initiated by tachycardia.
o Brotmacher(1957) proposed that squatting acutely angulated the lower limb blood vessels.
o Blood flow to the lower limbs is decreased whereas the increased cardiac output is confined to the upper part of the body.
o Result is the lessened Arteriovenous O2 difference and the hypoxia to vital centers is reduced thereby providing relief to the child.
Some more postures providing the squatting equivalent relief, as proposed by Taussig(1947);-
Sitting down with legs drawn underneath. Sitting with legs drawn underneath Legs crossed while standing. Holding the child with legs flexed up to the
abdomen. Lying down.
B. Morphine Sulphate(MS);-
- 0.2 mg/kg can be given I/M, S/C and I/V.
- Morphine suppresses the respiratory center and abolishes the hyperpnoea.
- Morphine has relaxing effect on Sub-Pulmonary Infundibulum– via CNS or through peripheral Vagotonic effect.
- Morphine sedates the patient thereby reducing the release of NE (Nor-Epinephrine).
C. Oxygen has a little effect on arterial saturation as the shunt is a central R to L shunt.
D. Propanolol ;- 0.01–0.25 mg/kg (average - 0.05mg /kg).
-- Half the dose is given as bolus ( slow push) and the remaining dose can be given as infusion ( over 5 – 10 mins.)
-- Propanolol reduces the heart rate and thus may reverse the spell.
-- Isopreterenol in case of Beta-blocker overdose.
E. Soda – Bicarb (NaHCo3) – 1 mEq/kg I/V.
- The same dose can be repeated in 10 – 15 mins.
-- reduces the respiratory center stimulating effect of acidosis.
If the hypoxic spell does not respond well to the already mentioned measures of treatment then;-
Vasoconstrictors like Phenalepherine 0.02mg/kg I/V.
Ketamine 1 – 3 mg/kg (average 2 mg/kg) I/V over 60 seconds.
-- It increases the SVR and sedates the child.
General Anesthesia (rarely required)- drugs like Cyclopropane, Halothane produce rapid induction which results in reduction of sympathetic activity and
consequently NE secretion.
Disopyramide (2 mg/kg ) has an advantage of not having any hypertensive response.
-- It has no systemic vasodilatory response.
Very rarely, when pt. is refractory to all these measures 0f treatment, then urgent Systemic to Pulmonary Artery Shunt surgery.
PREVENTION OF SPELL ;-
o Propanolol (1–4mg/kg), orally in divided doses is highly effective.
-- It helps defer the surgery till a time when the child is older and the risk of surgery is low.
Complications ;- repeated spells may lead to brain damage and mental retardation.
-- Prolonged hypoxic spells may lead to Cerebral Venous Sinus Thrombosis and Smaller Occult Thrombosis.
-- Repeated spells also hamper the growth
• 2.Neurological complications —• Patients with cyanotic heart disease are at risk
for paradoxical cerebral emboli which may lead to stroke or brain abscess .
• The impact of microspherocytosis on the risk of cerebrovascular events is uncertain, but a conservative approach toward phlebotomy is generally recommended.
• Atrial arrhythmias and transvenous pacing leads may increase the risk of embolic events.
• Nonischemic neurologic complications :• INFECTIOUS DISORDERS
• Brain abscess — An association between brain abscess and congenital heart disease is well established .
• the incidence has been estimated at 2 percent . – Protracted headache– Focal neurologic signs– Persistent fever– Seizures caused by an acute abscess may persist long
after healing or may recur years later because of focal scarring.
– The diagnosis of a fresh brain abscess can be made by computerized tomography, which identifies the abscess itself and the distinctive ring enhancement.
• The etiologies include – septic cerebral embolus, – contiguous extension of infection from otitis media, mastoiditis,
or sinusitis, and– facial or dental infection.
• Less clear is the pathogenesis of what has been called a "hematogenous" brain abscess .
• Two preconditions, often associated with cyanotic congenital heart disease appear to be necessary.– Bacteremia involving the cerebral circulation– A focal zone of cerebral vulnerability (ie, injury)– Fischbein CA, Rosenthal A, Fischer EG, et al. Risk factors of brain
abscess in patients with congenital heart disease. Am J Cardiol 1974; 34:97.
• A right-to-left shunt permits blood-borne bacteria, normally filtered by the pulmonary circulation, to enter the systemic and therefore the cerebral circulations.
• An area vulnerable to bacteriologic infection can result from a silent sterile paradoxical cerebral embolus or from a zone of encephalomalacia .
• Treatment of a brain abscess almost always requires aspiration using a CT-directed stereotactic technique in conjunction with antibiotic therapy.
• Resection of the abscess is rarely required– Shahler RM, Deuchar DC. Hematogenous brain abscess in
cyanotic congenital heart disease. Report of three cases, with complete transposition of the great vessels. Am J Med 1972; 52:349.
• Septic cerebral aneurysm — • A septic or bacterial cerebral aneurysm, often incorrectly
referred to as a mycotic aneurysm, usually results from a septic embolus originating at a site of infective endocarditis .
• Thus, a patient with infective endocarditis who develops focal neurologic signs or meningitis should undergo a cerebral CT scan followed by cerebral angiography .
• Urgent neurosurgical intervention is obligatory to prevent rupture which has a high mortality .– Yamada M, Miyasaka Y, Takagi H, Yada K. Cerebral bacterial
aneurysm and indications for cerebral angiography in infective endocarditis. Neurol Med Chir (Tokyo) 1994; 34:697.
• 3.Erythrocytosis and anemia —• Patients with cyanosis develop secondary
erythrocytosis.• This is a physiologic response, since the cyanotic
blood simulates the bone marrow to produce more red blood cells in an attempt to improve tissue oxygenation.
• Stable erythrocytosis and a new equilibrium are usually established at an appropriate level.
• In some patients, however, hematopoiesis increases dramatically and the hemoglobin rises to over 20 g/dL with an hematocrit of more than 65 percent.
• Symptoms of hyperviscosity may develop, such as headache, loss of concentration, muscle weakness, and fatigue.
• Volume depletion can cause identical symptoms and must be excluded.
• The treatment for symptomatic hyperviscosity is the lowering of red blood cell mass via phlebotomy, which should be carried out slowly with simultaneous infusion of isovolumic fluid.
• Target HCT-45-50%
• Amount of blood removed in phlebotomy-
Pt HCT-Desired HCT * body wt*100/Pt HCT
• Complications of phlebotomies• Frequent phlebotomies and iron deficiency anemia should
be avoided, since rebound erythropoiesis can occur, with production of iron deficient red blood cells (microspherocytes).
• Microspherocytes have reduced oxygen carrying capacity as well as increased rigidity and fragility.
• As a result, there is an increase in whole blood viscosity (with the associated symptoms noted above) as well as possible symptoms of iron deficiency anemia (weakness, headache, irritability, and varying degrees of fatigue and exercise intolerance).
• There is debate about a potential increase in risk of cerebrovascular events in patients with rebound erythropoiesis and microspherocytosis.
• In one report, 162 patients with cyanotic congenital heart disease were retrospectively evaluated for any well-documented cerebrovascular events that occurred at ≥18 years of age.
• Twenty-two patients (13.6 percent) had 29 cerebrovascular events (a rate of about 1 percent per year).
• Patients who had a cerebrovascular event had a significantly increased tendency to develop hypertension, atrial fibrillation, microcytosis (mean corpuscular volume <82), and a history of phlebotomy.
• Even when patients with hypertension or atrial fibrillation were excluded, there was an increased risk of cerebrovascular events associated with microcytosis.
Ammash N, Warnes CA. Cerebrovascular events in adult patients with cyanotic
congenital heart disease. J Am Coll Cardiol 1996; 28:768.
• In another report, 112 patients with cyanotic congenital heart disease followed for almost seven years were divided into two groups:
• those with "compensated" erythrocytosis (stable hematocrit of 46 to 73 percent, iron replete, and absent or mild viscosity symptoms),
• those with "decompensated" erythrocytosis (unstable rising hematocrit of 62 to 75 percent, iron deficiency, and marked to severe hyperviscosity symptoms).
• No patient in either group suffered a stroke
Perloff JK, Marelli AJ, Miner PD. Risk of stroke in adults with cyanotic congenital heart disease. Circulation 1993; 87:1954.
• Guidelines and recommendations —• Rather than solely using a target hematocrit, phlebotomy
should be performed only in patients with intrusive symptoms of hyperviscosity, and then only with caution in the setting of iron deficiency. Some experts also recommend preoperative phlebotomy to improve hemostasis.
• The ACC/AHA guidelines recommend therapeutic phlebotomy for hemoglobin greater than 20 g/dL and hematocrit >65 percent, associated with headache, increasing fatigue, or other symptoms of hyperviscosity in the absence of dehydration or anemia.
• Repeated routine phlebotomies are not recommended .
• 4.Symptomatic anemia • In cyanotic patients - due to iron deficiency resulting from
rebound erythrocytosis or bleeding.• The ACC/AHA guidelines recommend avoidance of iron
deficiency in patients with cyanotic heart disease and/or Eisenmenger syndrome.
• target HB-15-17gm/dl• The treatment of iron deficiency is iron therapy which
should be administered with care since iron supplementation may lead to rapid increases in red cell mass.
• Although there are no specific data regarding timing, recommended iron supplementation be instituted when the mean corpuscular volume is less than 82, since microspherocytes may increase the cerebrovascular risk .
• Iron should be discontinued when the hematocrit begins to rise, usually within 7 to 10 days.
Body wt * 2.3*(15-Pt Hb)+500
• 4.Hemostasis — • Cyanotic patients have an increased risk of
hemorrhage due to a number of hemostatic abnormalities documented in up to 20 percent of patients;– elevations in the prothrombin and partial thromboplastin
times,– reduced coagulation factors,– thrombocytopenia, and – abnormal platelet function.– However, pulmonary bleeding and menorrhagia are
common.
• Pulmonary bleeding —(adult patients)• Hemoptysis is external bleeding and does not reflect the
extent of intrapulmonary hemorrhage, which is a serious and life-threatening problem for Eisenmenger and other cyanotic patients and can reflect rupture of the pulmonary trunk or a bronchial artery .
• Bronchoscopy is associated with significant risk and rarely discloses the cause of hemoptysis; as a result, this procedure should be avoided .
• CT-PA should be performed to determine the presence and extent of intrapulmonary hemorrhage.
• ACC/AHA guidelines note that anticoagulation is contraindicated in patients with active or chronic hemoptysis.
• Menorrhagia —• Menorrhagia is a common problem in women
with cyanotic heart disease and, if severe, can lead to iron deficiency anemia.
• Suppression of menorrhagia with hormonal stimulation is often helpful; however, hysterectomy is occasionally required.
• Anticoagulation — NOT recommended routinely. Exceptions to this rule :– Atrial fibrillation– Documented pulmonary thrombosis or embolism– Transient ischemic attack or stroke without
evidence of microcytosis or other identifiable and treatable cause
– Deep venous thrombosis– Placement of an indwelling device (such as a
permanent pacemaker) in the right side of the heart.
• 5.Renal dysfunction — • Renal dysfunction in cyanotic patients is primarily
manifested as decreased urate clearance, leading to hyperuricemia , and, in occasional patients, proteinuria that is associated with a glomerulopathy .
• The BUN and serum creatinine concentration are typically normal but susceptibility to radiopaque contrast media and dehydration remains a concern.
• The 2008 ACC/AHA guidelines recommend that uric acid and creatinine levels be assessed at least yearly in Eisenmenger syndrome patients.
• Drugs that can impair renal function, such as ACE inhibitors, diuretics, and nonsteroidal antiinflammatory drugs should be avoided or used with caution.
• If administration of radiographic contrast agent is planned, the glomerular filtration rate should be assessed, intravenous fluids administered as appropriate and other precautions considered
• 6.Hyperuricemia — • Among patients with cyanotic congenital heart diseases,
the serum uric acid rises in proportion to the degree of hypoxemia and hemodynamic deterioration .
• Hyperuricemia can lead to gout but rarely to renal failure, since the hyperuricemia is primarily due to reduced excretion rather than increased production.
• Therapy is not necessary in asymptomatic patients.• Among patients who develop gout, allopurinol or
colchicine is preferred; nonsteroidal antiinflammatory drugs should be avoided because they interfere with platelet function and hemostasis and may impair renal function.
• 7.Pigment gallstones — • Increased red blood cell turnover and subsequent
production of unconjugated bilirubin can result in pigment (calcium bilirubinate) gallstones.
• The major risk of cholelithiasis is the development of acute cholecystitis with the need for emergency surgery.
• Surgery is not recommended until patients become symptomatic .
• 8.Orthopedic problems — • Orthopedic problems, such as scoliosis, are
present in approximately 25 to 30 percent of patients with congenital heart disease.
• The etiology of scoliosis is unknown but can be disabling, can contribute to cyanosis and functional incapacity due to pulmonary restriction, and may require consideration of high-risk surgical intervention.
• 9.Other considerations — • During long-distance flights, cyanotic patients
should drink nonalcoholic and noncaffeinated fluids to avoid dehydration and the diuretic effects of alcohol and caffeine. Supplemental oxygenation may be considered.
• Competitive sports should be avoided in cyanotic patients.
• 10.Endocarditis prophylaxis — • AHA guidelines on the prevention of infective
endocarditis recommend antimicrobial prophylaxis for all patients with unrepaired cyanotic congenital heart disease
• All dental procedures that involve manipulation of either gingival tissue or the periapical region of teeth or perforation of the oral mucosa.
• Procedures of the respiratory tract that involve incision or biopsy of the respiratory mucosa.
• Procedures in patients with ongoing GI or GU tract infection.
• Procedures on infected skin, skin structure, or musculoskeletal tissue.
• Surgery to place prosthetic heart valves or prosthetic intravascular or intracardiac materials.
• Prostaglandins PGE1(0.05 to 0.1mcg/kg/min.)/PGE2
• To maintain ductal patency– HLHS– PA intact IVS– D-TGA
Prostaglandin E1
• Apnea
• Vasodilation/Hypotension
• Fever
• Seizures (rare)
• May “unmask” CHD with obstruction to PV return– d-TGA-intact atrial septum– TAPVR– Mitral atresia with restrictive atrial septum
Side Effects of PGE-1 By Birth Weight
<2 >2KG KG
_____________________________________CV 37% 17%CNS 16 16Respiratory 42 10Metabolic 5 2Infectious 11 2GI 11 3Hematologic 5 2Renal 0 2
• Apnea – caffeine, intubate• Hypotension – volume, pressors• Seizures – anti-seizure meds
Dealing with Side Effects of PGE-1
SURGERY• Palliative-• Curative-
CLASSIC BLALOCK-TAUSSIG SHUNT MODIFIED BLALOCK-TAUSSIG SHUNT
SYSTEMIC TO PULMONARY ARTERY SHUNTING
The classic Blalock-Taussig shunt consists of an end-to-side anastomosis of the subclavian and pulmonary artery. B, The modified Blalock-Taussig shunt consists of an interposition tube graft that connects the subclavian artery to the ipsilateral pulmonary artery.
• Classic BT shunt 1945 – artificial ductus arteriosus.
• involved ligation and division of the left subclavian artery, with anastomosis of the proximal subclavian artery to the PA. opposite to side of arch-
• more mobility and less acute angle so kinking is less likely.
• This resulted in a reliable source of pulmonary blood flow that usually increased over time as the child grew .
• Disadvantages of classic BT– Phrenic nerve damage– Recurrent ;aryngeal nerve damage-vocal cord
paralyisis– Cervical sympathetic chain damage-horner– Chylo thorax/haemothorax– potential distortion and kinking of the PA in
patients with a small subclavian artery and– possible abnormal growth and strength of the
arm ipsilateral to the shunt (steal phenomenon)
• Recent modified BT shunt• Involves interposing a
prosthetic graft of polytetrafluoroethylene between the subclavian artery and ipsilateral right or left PA
• Benefits of the modified BT shunt include technical ease of the procedure (which can be performed on either side of the aortic arch), wide anastomoses proximally and distally, and preserved blood flow to the ipsilateral arm .
• Disadvantages• Thrombosis of a modified BT shunt is not uncommon
and may be life threatening.• Although usually a late complication (occurring
months to years after shunt creation), thrombosis can occur in the early postoperative period as well.
• Diagnosis -echocardiography /CT angiography / MR imaging.
• While subtotal occlusion or stenosis of a BT shunt is typically treated with shunt revision, treatment with balloon angioplasty and stent placement has been described
• A seroma adjacent to the shunt. This is caused by seepage of fluid across the polytetrafluoroethylene graft.
• If large enough- airway compression or pericardial tamponade.
• The diagnosis of a seroma-echocardiography/CT.• US-guided percutaneous drainage of these
seromas .
POTTS SHUNT
• Potts 1946• between the descending
aorta and ipsilateral pulmonary
• When SCA small or poorly developed
• Disadvantages– Difficult to close during
definitive repair– Pulmonary
hypertension due to enlargement of anastamotic channel
Waterston
• 1962• Waterston shunt
consists of a connection between the ascending aorta and pulmonary artery,
• more easely closed
• The original Glenn shunt 1958• The shunt was intended to palliate congenital heart defects
in which there was hypoplasia or atresia of rightsided structures of the heart—conditions such as tricuspid atresia, Epstein anomaly, and pulmonary atresia with intact ventricular septum.
• consists of an end-to-end anastomosis of the right PA (divided from the main PA) to the side of the SVC.
• The SVC is ligated at its entrance to the right atrium, directing all proximal SVC blood flow to the right PA.
• The azygos vein is also ligated.
• BDG shunt• The BDG shunt consists of an
end-to-side anastomosis between the SVC (again divided from the right atrium) and the right PA.
• Because the right PA is not divided from the main PA in this procedure, the BDG shunt directs flow from the SVC into the right and left PAs.
• If there are two SVCs that are similar in size, each is anastomosed to its respective ipsilateral PA .
• Currently, the BDG shunt is used as a staging procedure in children with single-ventricle physiology who will ultimately require a Fontan procedure .
• Because adequate flow through the shunt depends on low pulmonary pulmonary vascular resistance, this procedure is typically performed between 3 and 9 months of life, after pulmonary vascular resistance falls from elevated neonatal levels.
• Even though most patients will have effective long-term palliation with the BDG, one long-term complication is the development of pulmonary arteriovenous fistulas.
• These malformations, which result in ineffective gas exchange, are thought to be due to the lack of hepatic venous blood perfusing the lungs.
• Humoral factors in the hepatic venous blood seem necessary to prevent formation of these fistulous communications.
• These fistulas can be diagnosed by using contrast agent–enhanced echocardiography, CT angiography, MR imaging, and conventional angiography.
• The BDG shunt is usually followed at 2–4 years of age by the complete Fontan procedure, which diverts all systemic venous return to the pulmonary vascular bed directly.
• This directs hepatic blood flow to the lungs, prevents the development of fistulas, and removes the volume overload on the heart
DEFINITIVE REPAIR
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