Anaesthesia for congenital heart disease
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Anaesthesia for congenital heart disease

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Anaesthesia for congenital heart disease Presentation Transcript

  • 1. Anesthesia for Congenital HeartDisease
  • 2. INCIDENCE • 7 to 10 per 1000 live births • Premature infants 2-3X higher incidence • Most common form of congenital disease • Accounts for 30% of total incidence of all congenital diseases • 10% -15% have associated congenital anomalies of skeletal, RT, GUT or GIT • Only 15% survive to adulthood without treatment
  • 3. 3
  • 4. CLASSIFICATION OF CHD • L - R SHUNTS INCLUDE : – ASD →7.5% of CHD – VSD → COMMONEST CHD – 25% – PDA → 7.5% of CHD • Common in premature infants – ENDOCARDIAL CUSHION DEFECT - 3% • Often seen with trisomy 21 – AORTOPULMONARY WINDOW
  • 5. CLASSIFICATION OF CHD • R – L SHUNTS – Defect between R and L heart – Resistance to pulmonary blood flow → ↓ PBF → hypoxemia and cyanosis • INCLUDE : – TOF – 10% of CHD, commonest R-L shunt – PULMONARY ATRESIA – TRICUSPID ATRESIA – EBSTEIN’S ANOMALY
  • 6. R – L SHUNTS • GOAL → ↑ PBF to improve oxygenation – Neonatal PGE1 (0.03 – 0.10mcg/kg/min) maintains PDA → ↑ PBF – PGE1 complications → vasodilatation, hypotension, bradycardia, arrhythmias, apnea or hypoventilation, seizures, hyperthermia – Palliative shunts → ↑ PBF, improve hypoxemia and stimulate growth in PA → aids technical feasibility of future repair
  • 7. Almost any anesthetic technicmay be used in any CHD patient if the anesthesiologist understands •the pathophysiology of the lesion and •the pharmacology of the drugs employed.
  • 8. ANESTHETIC MANAGEMENT • Perioperative management requires a team approach • Most important consideration is necessity for individualized care • CHD is polymorphic and may clinically manifest across a broad clinical spectrum
  • 9. ANESTHETIC MANAGEMENT • 50% Dx by 1st week of life; rest by 5 years • Child’s diagnosis & current medical condition will determine preoperative evaluation • Understand the anatomic and hemodynamic function of child’s heart • Discuss case with pediatrician and cardiologist • Review diagnostic & therapeutic interventions • Above will estimate disease severity and help formulate anesthetic plan
  • 10. HISTORY & PHYSICAL • Assess functional status – daily activities & exercise tolerance • Infants - ↓ cardiac reserve → cyanosis, diaphoresis & respiratory distress during feeding • Palpitations, syncope, chest pain • Heart murmur (s) • Congestive heart failure • Hypertension
  • 11. HISTORY & PHYSICAL • Tachypnea, dyspnea, cyanosis • Squatting • Clubbing of digits • FTT d/t limited cardiac output and increased oxygen consumption • Medications – diuretics, afterload reduction agents, antiplatelet, anticoagulants • Immunosuppressants – heart transplant
  • 12. LABORATORY EVALUATION • BLOODWORK • Electrolyte disturbances 2° to chronic diuretic therapy or renal dysfunction • Hemoglobin level best indicator of R-L shunting magnitude & chronicity • Hematocrit to evaluate severity of polycythemia or iron deficiency anemia • Screening coagulation tests • Baseline ABG & pulse oximetry • Calcium & glucose - newborns, critically ill children
  • 13. LABORATORY EVALUATION • 12 LEAD EKG – Chamber enlargement/hypertrophy – Axis deviation – Conduction defects – Arrhythmias – Myocardial ischemia
  • 14. LABORATORY EVALUATION • CHEST X - RAY – Heart size and shape – Prominence of pulmonary vascularity – Lateral film if previous cardiac surgery for position of major vessels in relation to sternum
  • 15. LABORATORY EVALUATION• ECHOCARDIOGRAPHY – Anatomic defects/shunts – Ventricular function – Valve function – Doppler & color flow imaging → direction of flow through defect/valves, velocities and pressure gradients
  • 16. LABORATORY EVALUATION • CARDIAC CATHERIZATION – Size & location of defects – Degree of stenosis & shunt – Pressure gradients & O2 saturation in each chamber and great vessel – Mixed venous O2 saturation obtained in SVC or proximal to area where shunt occurs – Low saturations in LA and LV = R – L shunt – High saturations in RA & RV = L – R shunt
  • 17. LABORATORY EVALUATION • CARDIAC CATHERIZATION – Determine shunt direction: ratio of pulmonary to systemic blood flow : Qp / Qs – Qp / Qs ratio < 1= R – L shunt – Qp / Qs ratio > 1= L – R shunt
  • 18. Congenital Cardiac Surgery • Preoperative medication – D/C diuretics and digoxin unless heart failure is poorly controlled or digoxin is being used primarily for rhythm – Continue inotropes – Continue prostaglandin infusions
  • 19. MONITORING • Routine CAS monitoring • Precordial or esophageal stethoscope • Continuous airway manometry • Multiple - site temperature measurement • Volumetric urine collection • Pulse oximetry on two different limbs • TEE
  • 20. MONITORING • PDA – Pulse oximetry right hand to measure pre-ductal oxygenation – 2nd probe on toe to measure post-ductal oxygenation • COARCTATION OF AORTA – Pulse oximeter on right upper limb – Pre and post - coarctation blood pressure cuffs should be placed
  • 21. ANESTHETIC MANAGEMENT • GENERAL PRINCIPLES P Q= R Where: Q= Blood flow (CO) P= Pressure within a chamber or vessel R= Vascular resistance of pulmonary or systemic vasculature Ability to alter above relationship is the basic tenet of anesthetic management in children with CHD
  • 22. ANESTHETIC MANAGEMENT P → manipulate with positive or negative inotropic agents Q → hydration + ↑preload and inotropes However, the anesthesiologist’s principal focus is an attempt to manipulate resistance, by dilators and constrictors
  • 23. ANESTHETIC MANAGEMENT • GENERAL CONSIDERATIONS – De-air intravenous lines air bubble in a R-L shunt can cross into systemic circulation and cause a stroke – L-R shunt air bubbles pass into lungs and are absorbed – Endocarditis prophylaxis – Tracheal narrowing d/t subglottic stenosis or associated vascular malformations
  • 24. ANESTHETIC MANAGEMENT – Tracheal shortening or stenosis esp. in children with trisomy 21 – Strokes from embolic phenomena in R-L shunts and polycythemia – Chronic hypoxemia compensated by polycythemia → ↑ O2 carrying capacity – HCT ≥ 65% → ↑ blood viscosity → tissue hypoxia & ↑ SVR & PVR → venous thrombosis → strokes & cardiac ischemia
  • 25. ANESTHETIC MANAGEMENT – Normal or low HCT D/T iron deficiency → less deformable RBCs → ↑ blood viscosity – Therefore adequate hydration & decrease RBC mass if HCT > 65% – Diuretics → hypochloremic, hypokalemic metabolic alkalosis
  • 26. Air Bubble precautions• To prevent paradoxical air embolism• Remove all bubbles from iv tubing• Connect the iv tubing to the venous cannula while there is free flowing in fluid .• Eject small amount of solution from syringe to clear air from the needle hub before iv injection• Aspirate injection port before injection to clear any air• Hold the syringe upright to keep bubbles at the plunger end• Do not leave a central line open to air• Use air filters• ? No N2O.
  • 27. PREMEDICATION a) Omit for infants < six months of age b) Administer under direct supervision of Anesthesiologist in preoperative facility c) Oxygen, ventilation bag, mask and pulse oximetry immediately available d) Oral Premedication • Midazolam 0.25 -1.0 mg/kg • Ketamine 2 - 4 mg/kg • Atropine 0.02 mg/kg
  • 28. PREMEDICATION e) IV Premedication • Midazolam 0.02 - 0.05 mg/kg titrated in small increments e) IM Premedication • Uncooperative or unable to take orally • Ketamine 1-2 mg/kg • Midazolam 0.2 mg/kg • Glycopyrrolate or Atropine 0.02 mg/kg
  • 29. ANESTHETIC AGENTS • INHALATIONAL AGENTS – Safe in children with minor cardiac defects – Most common agents used are halothane and sevoflurane in oxygen – Monitor EKG for changes in P wave → retrograde P wave or junctional rhythm may indicate too deep anesthesia
  • 30. INHALATIONAL ANESTHETICS • HALOTHANE – Depresses myocardial function, alters sinus node function, sensitizes myocardium to catecholamines ↓ MAP + ↓ HR ↓ CI + ↓ EF • Relax infundibular spasm in TOF • Agent of choice for HOCM
  • 31. INHALATIONAL ANESTHETICS SEVOFLURANE • No ↓ HR • Less myocardial depression than Halothane • Mild ↓ SVR → improves systemic flow in L- R shunts • Can produce diastolic dysfunction
  • 32. INHALATIONAL ANESTHETICS ISOFLURANE • Pungent → not good for induction • Incidence of laryngospasm > 20% • Less myocardial depression than Halothane • Vasodilatation leads to ↓ SVR → ↓ MAP ∀ ↑ HR which can lead to ↑ CI
  • 33. INHALATIONAL ANESTHETICS DESFLURANE • Pungent → not good for induction; highest incidence of laryngospasm • SNS activation → ↓ with fentanyl ∀ ↑ HR + ↓ SVR • Less myocardial depression than Halothane
  • 34. INHALATIONAL ANESTHETICS NITROUS OXIDE • Enlarge intravascular air emboli • May cause microbubbles and macrobubbles to expand → ↑ obstruction to blood flow in arteries and capillaries • In shunts, potential for bubbles to be shunted into systemic circulation
  • 35. INHALATIONAL ANESTHETICS NITROUS OXIDE • At 50% concentration does not affect PVR and PAP in children • Mildly ↓ CO at 50% concentration • Avoid in children with limited pulmonary blood flow, PHT or ↓ myocardial function
  • 36. IM & IV ANESTHETICS KETAMINE • No change in PVR in children when airway maintained & ventilation supported • Sympathomimetic effects help maintain HR, SVR, MAP and contractility • Greater hemodynamic stability in hypovolemic patients • Copious secretions → laryngospasm → atropine or glycopyrrolate
  • 37. IM & IV ANESTHETICS KETAMINE • Relative contraindications may be coronary insufficiency caused by: – anomalous coronary artery – severe critical AS – hypoplastic left heart syndrome with aortic atresia – hypoplasia of the ascending aorta • Above patients prone to VF d/t coronary insufficiency d/t catecholamine release from ketamine
  • 38. IM & IV ANESTHETICS IM Induction with Ketamine: • Ketamine 5 mg/kg • Succinylcholine 5 mg/kg or Rocuronium 1.5 – 2.0 mg/kg • Atropine or Glycopyrrolate 0.02 mg/kg IV Induction with Ketamine: • Ketamine 1-2 mg/kg • Succinylcholine 1-2 mg/kg or Rocuronium 0.6-1.2 mg/kg • Atropine or Glycopyrrolate 0.01 mg/kg
  • 39. IM & IV ANESTHETICS OPIOIDS • Excellent induction agents in very sick children • No cardiodepressant effects if bradycardia avoided • If used with N2O - negative inotropic effects of N2O may appear • Fentanyl 25-100 µg/kg IV • Sufentanil 5-20 µg/kg IV • Pancuronium 0.05 - 0.1 mg/kg IV → offset vagotonic effects of high dose opioids
  • 40. IM & IV ANESTHETICS ETOMIDATE • CV stability • 0.3 mg/kg IV THIOPENTAL & PROPOFOL • Not recommended in patients with severe cardiac defects • In moderate cardiac defects: – Thiopental 1-2 mg/kg IV or Propofol 1-1.5 mg/kg IV – Patient euvolemic
  • 41. ANESTHETIC MANAGEMENT ANESTHESIA INDUCTION • Myocardial function preserved → IV or inhalational techniques suitable • Severe cardiac defects → IV induction • Modify dosages in patients with severe failure
  • 42. ANESTHESIC MANAGEMENT ANESTHESIA MAINTENANCE • Depends on preoperative status • Response to induction & tolerance of individual patient • Midazolam 0.15-0.2 mg/IV for amnesia
  • 43. ANESTHETIC MANAGEMENT • L - R SHUNTS : • Continuous dilution in pulmonary circulation may ↑ onset time of IV agents • Speed of induction with inhalation agents not affected unless CO is significantly reduced • Degree of RV overload and/or failure underappreciated – careful induction
  • 44. ANESTHETIC MANAGEMENT • L-R SHUNTS : – GOAL = ↓ SVR and ↑ PVR → ↓ L-R shunt • PPV & PEEP increases PVR • Ketamine increases SVR • Inhalation agents decrease SVR
  • 45. ANESTHETIC MANAGEMENT • R-L SHUNTS : – GOAL :↑ PBF by ↑ SVR and ↓ PVR ∀ ↑ PVR & ↓ SVR → ↓ PBF – Hypoxemia/atelectasis/PEEP – Acidosis/hypercapnia ↑ HCT – Sympathetic stimulation & surgical stimulation – Vasodilators & inhalation agents → ↓ SVR
  • 46. ANESTHETIC MANAGEMENT • ↓ PVR & ↑ SVR → ↑ PBF – Hyperoxia/Normal FRC – Alkalosis/hypocapnia – Low HCT – Low mean airway pressure – Blunted stress response – Nitric oxide/ pulmonary vasodilators – Vasoconstrictors & direct manipulation→↑ SVR
  • 47. ANESTHETIC MANAGEMENT • R –L SHUNTS : – Continue PE1 infusions – Adequate hydration esp. if HCT > 50% – Inhalation induction prolonged by limited pulmonary blood flow – IV induction times are more rapid d/t bypassing pulmonary circulation dilution – PEEP and PPV increase PVR
  • 48. ANESTHETIC MANAGEMENT • COMPLEX SHUNTS : • Manipulating PVR or SVR to ↑ PBF will: • Not improve oxygenation • Worsen biventricular failure • Steal circulation from aorta and cause coronary ischemia • Maintain “status” quo with high dose opioids that do not significantly affect heart rate, contractibility, or resistance is recommended
  • 49. ANESTHETIC MANAGEMENT • COMPLEX SHUNTS : – Short procedures slow gradual induction with low dose Halothane least effect on +ve chronotropy & SVR – Nitrous Oxide limits FiO2 & helps prevent coronary steal & ↓ Halothane requirements
  • 50. ANESTHETIC MANAGEMENT • OBSTRUCTIVE LESIONS • Lesions with > 50 mmHg pressure gradient + CHF → opioid technique • Optimize preload → improves flow beyond lesion • Avoid tachycardia → ↑ myocardial demand & ↓ flow beyond obstruction • Inhalation agents → -ve inotropy & decrease SVR→ worsens gradient & flow past obstruction
  • 51. Congenital Cardiac Surgery • Cardiopulmonary Bypass – Differences from adult • Lower temperatures (15-20 degrees C) • Lower perfusion pressure (20-30mmHg) • Very significant hemodilution (3-15 times greater) • Pump flows range from 200ml/kg/min to zero! • Different blood pH management (alpha-stat vs pH stat) • Tendency to hypoglycemia • Cannula placement is much more critical
  • 52. Anticoagulation and haemostasis during CPB AnticoagulationHeparin• time of administration• Route – central line
  • 53. Current clinical protocol• Heparin – 300 units/kg i.v.• Draw arterial sample for ACT in 3-5 min.• Give additional heparin to achieve ACT >300 (normothermic CPB) ACT > 400 (hypothermic CPB)• Prime extracorporial circuit with heparin 3 units/ml•
  • 54. • Monitor ACT every 30 min. during CPB• If ACT decreases below desired minimum value – supplemental dose of 50-100 units/kg
  • 55. HaemostasisAt conclusion of CPB• Protamine – mainstay of heparin neutralization• Dosage – 1.3 mg to neutralise 100units of heparin• ACT after administration if more then baseline – additional bolus (25 -50mg) of protamine
  • 56. protamine reaction• Increase in PAP & CVP• Decrease in LAP & SAP Precaution• via peripheral line• Administer slowly < 5mg/min.• Test bolus dose 25-50 mg – look for haemodynamics• Careful with pt. having food allergy
  • 57. Treatment• Stop protamine• Administration of fluids and epinephrine• Steroids• Pulmonary vasodialators - NTG, SNP
  • 58. Congenital Cardiac Surgery • Deep hypothermic circulatory arrest (DHCA) – Neonates and small infant usually < 10 kg – Oxygen consumption falls 2-2.5 times per 10 degree fall in temperature – Allows more controlled complex surgery in a bloodless field – Often total CPB time is actually shortened by this technique
  • 59. Congenital Cardiac Surgery • Weaning from CPB – Heart assessed by direct visualization and right or left atrial filling pressure, central cannula or TEE – Pulse oximetry is also very helpful – Problems weaning are due to: • Inadequate repair, • pulmonary hypertension • And/or left or right ventricular dysfunction
  • 60. Congenital Cardiac Surgery • Weaning from CPB – Problems weaning diagnosed by • Intraoperative cardiac catheterization • Echo-doppler – Leaving the operating room before correcting the problem leads to a significant INCREASE in morbidity
  • 61. Postoperative care• Observation on a monitored bed in ICU/HDU for 24 hours or overnight atleast because of their predisposition to develop ventricular/ supraventricular tachycardia, bradyarrhythmia and myocardial ischemia• Meticulous attention to fluid balance to prevent hypovolumia• Monitoring of blood pressure preferably invasive, Oxygen saturation and CVP• Position slowly- risk of postoperative postural hypotension with secondary increase in right to left shunting• Prevention of venous stasis by early ambulation and by applying effective elastic stocking or periodic pneumatic compression.• Adequate pain management – adverse hemodynamics and possibly hypercoagulable state
  • 62. Post op pain management • Opioid analgesia • Regional analgesia • Alternative and supplementary analgesia
  • 63. Congenital Cardiac Surgery • Selected Specific Conditions/Procedures: – Tetralogy of Fallot – Patent Ductus Arteriosus(PDA) – ASD – VSD
  • 64. TETRALOGY OF FALLOT
  • 65. TETRALOGY OF FALLOT • 10% of all CHD • Most common R – L shunt • 4 anomalies: – RVOT obstruction ( infundibular, pulmonic or supravalvular stenosis ) – Subaortic VSD – Overriding aorta – RVH
  • 66. CXR IN TOF • Normal heart size • Pulmonary oligemia • Upturned cardiac apex • Rt aortic arch
  • 67. TOF : CoagulationAbnormalities • Thrombocytopenia • Platelet functional defects • Hypofibrinogenemia • Elevated PT, APTT.
  • 68. Congenital Cardiac Surgery • Laboratory data – Cyanosis leads to polycythemia • May consider phlebotomy esp if no CPB • Leads to coagulation problems – Anemia may be “relative” and need transfusion – Newborn infant has immature systems including renal/hepatic/coagulation – Hypoglycemia is much more common
  • 69. Airway Abnormalities inTOF • TOF with pulmonary atresia: tracheomalacia, bronchomalacia • Associated syndromes – DiGeorge syndrome, CHARGE, Goldenhar’s syndrome, Down’s syndrome.
  • 70. TETRALOGY OF FALLOT • Hypercyanotic ( “tet” ) spells occur D/T infundibular spasm, low pH or low PaO2 • In awake patient manifests as acute cyanosis & hyperventilation • May occur with feeding, crying, defecation or stress • During anesthesia D/T acute dynamic infundibular spasm
  • 71. Triggers • ↑O2 demand • crying feeding defecation • Hypovolemia • Relative anemia • Anxiety • Hypoxia hypercarbia acidosis
  • 72. TETRALOGY OF FALLOT • Treatment of Hypercyanotic Spells – High FiO2 → pulmonary vasodilator → ↓ PVR – Hydration (fluid bolus) → opens RVOT – Morphine (0.1mg/kg/dose) → sedation,↓ PVR – Ketamine → ↑ SVR, sedation, analgesia → ↑ PBF – Phenylephrine (1mcg/kg/dose) → ↑ SVR – β-blockers (Esmolol 100-200mcg/kg/min) → ↓HR,-ve inotropy → improves flow across obstructed valve &↓ infundibular spasm
  • 73. Volatile Esmolol Propranolol ↑ depth of ↓ HR & anesthesia contractility↑ pre load ↓ infundibular spasm↓ acidosis TREATMENT(NaHCO3) ↑SVR ↓ PVRPhenylnephrine norepinephrine posture1-10µg/kg 0.01µg/kg
  • 74. Congenital Cardiac Surgery • Tetralogy of Fallot – Preoperative Preparation • Heavy premedication – Consider IM ketamine or inhalation induction but get rapid control of airway. – Keep SVR up and PVR down, maintain heart rate – Intraoperative TEE
  • 75. Congenital Cardiac Surgery • Tetralogy of Fallot – Weaning from CPB, ratio RV:LV pressure should be < 0.8 – May need to keep PVR low with NTG, milrinone, dobutamine phentolamine, PGE1 – May need RV inotrope post op – May need temporary pacing wire
  • 76. Congenital Cardiac Surgery • Tetralogy of Fallot – Perioperative concerns • Increase in PVR or decrease in SVR leading to Right to Left shunt • Tet Spells pre induction (crying/anxiety) • Polycythemia and bleeding • Air embolus • RV failure
  • 77. PALLIATIVE SHUNTS INTOF • Blalock-Taussig shunt [anastomosis of subclavian artery and pulmonary artery] • Modified B-T shunt [Goretex graft used] • Pott’s shunt [descending aorta  left pulmonary artery] • Waterston’s shunt [ascending aorta  right pulmonary artery]
  • 78. Patent Ductus Arteriosus • Ductus Arteriosus connects the descending aorta to the main pulmonary trunk near the origin of the left subclavian • Normal postnatal closure results in fibrosis- which becomes the ligamentum arteriosum. • Small PDA does not increase risk for heart failure- but does carry a risk for bacterial endocarditis.
  • 79. Congenital Cardiac Surgery• PATENT DUCTUS ARTERIOSUS – 1/8000 live births, associated with prematurity and female predominance of approx 3:1 – Left to right shunt causes pulmonary edema – Occasionally right to left cause lower body cyanosis – SpO2 probe on Right hand and lower limb • Confirms correct vessel ligated – Vagal reflex is pronounced by lung traction – Antibiotics required to prevent endocarditis
  • 80. • Confirmation of crossmatched blood in OT.• Radial arterial line preferably on opposite side of aortic arch.• At the time of PDA ligation SBP reduced to 80-90 mm of hg with Halothane/SNP• Watch for haemorrhage due to rupture.
  • 81. Thank you!!