seminar on TOF

seminar on TOF

1. WELCOME Dr. A.K.M. Kamruzzaman FCPS Student, BSMMU.

2. Tetralogy of Fallot

3. Overview Epidemiology Pathophysiology Hemodynamic Clinical presentation Blue spell Evaluation Complication Management Prognosis

4. History 1671 Danish anatomist Nils Steno The first description 1777 Sandifort described a .“blue boy.” with the anatomic features of TOF 1784 William Hunter cyanotic spells and poor growth in a boy with TOF Louis-Etienne Fallot ( A French physician) in 1888 , first correlate the clinical and pathological features of TOF 1924 Maude Abbott coined the term“tetralogy of Fallot .” 1936 produced the first illustrations of the pathologic and circulatory features, and described x-ray and electrocardiographic features of TOF

5. One of the conotruncal family of heart lesions Primary defect is an anterior deviation of the infundibular septum - Obstruction of RVOT(PS) - VSD - Overriding of aorta - RVH Tetralogy of fallot

6. Most common congenital cyanotic heart disease Occurs in 3 of every 10,000 live births, and Accounts for 7–10% of all congenital cardiac malformations. Epidemiology

7. Multifactorial But associations include untreated maternal diabetes, phenylketonuria , & intake of retinoic acid. Associated chromosomal anomalies include trisomies 21, 18, and 13 The risk of recurrence in families is 3%. Etiology Recent experience points to the much more frequent association of microdeletions of chromosome 22. 22q11.2 deletion syndrome

8. Developmental Fault Defective embryonic neural crest migration- abnormal conotruncal development. Incomplete rotation and faulty partitioning of the conotruncus during separation. Malrotation of truncal-bulbar ridges results in mis -alignment of the outlet and trabecular septum and consequent straddling of the aorta over the malaligned VSD. Abnormally anterior septation of the conotruncus by the bulbotruncal ridges- subpulmonic obstruction.

9. Lesion Frequency in TOF Structural Pulmonary atresia Atrial septal defect Additional VSD Atrioventricular septal defect PDA Dextrocardia 12% 20% 5% 1-3% 4-6% 2% Vascular Right aortic arch Congenital absence of Pul valve Coronary artery anomaly Aberrant subclavian artery MAPCAS 15-25% 3% 3-8% 2% Additional structural and vascular lesions in TOF

10. Hemodynamic

11. Tetralogy Of F allot Obstruction of RVOT(PS) Ventricular septal defect Overriding of aorta Right ventricular hypertrophy

12. Pathophysiology Owing to right ventricular obstruction during ventricular systole deoxygenated blood of right ventricle shunts through VSD to the left ventricle, mix with oxygenated blood and this mixed blood passes through the aorta to different parts of the body.

13. The flow occurs across the pulmonic stenosis producing an ejection systolic murmur -- more severe the pulmonic stenosis, the less the flow into the pulmonary artery and the bigger the right to left shunt more severe the pulmonic stenosis, the shorter the ejection systolic murmur and the more the cyanosis the severity of cyanosis is directly proportional to the severity of pulmonic stenosis, but the intensity of the systolic murmur is inversely related to the severity of pulmonic stenosis

14. the right ventricular outflow obstruction results in the delay in the P2 --  since the pulmonary artery pressure is reduced, the P2 is also reduced in intensity -- the late and soft P2 is generally inaudible in TOF -- the S2 is , therefore, single and the audible sound is A2 -- since the aorta is somewhat anteriorly displaced, the audible single A2 is quite loud .

15. The VSD of TOF is always large enough to allow free exit to the right to left shunt ---  since the right ventricle is effectively decompressed by the VSD --- congestive failure almost never occurs in TOF. As the systolic pressures between two ventricle are identical there is little or no shunt and the VSD is silent

16. The degree of RVOT obstruction determines The timing of the onset of symptoms Severity of cyanosis Degree of RVH RVOT obstruction Mild- moderate Balanced shunt across the VSD No visibly cyanosed-Pink TOF Severe Cyanosis will be present from birth

17. Clinical Features From History Exertional dyspnea Cyanosis Paroxysomal blue spells Growth failure Developmental delay

18. Cyanosis , clubbing Conjunctival congestion Pulse: Normal Blood pressure : Normal Normal sized heart with parasternal impulse, a systolic thrill in less than 30 % patients. Physical examination

19. Normal first sound, Single second sound An ejection systolic murmur : Loud & harsh, most intensity at the left sternal border Occasionally continuous murmur ( if prominent collaterals are present) Physical examination

20. Paroxysmal hypercyanotic attack Hypoxic, blue or tet spell Particular problem during the 1 st 2 years of life Hyperpneic , restless, cyanosis increases, gasping respiration & syncope Frequently occur in the morning on awakening or after episodes of vigorous crying Last for few min to hrs Onset is spontaneous & unpredictable

21. Paroxysmal hypercyanotic attack Short episodes are followed by generalized weakness & sleep Severe spell progress to unconsciousness, occasionally to convulsion/ hemiparesis Temporary disappearance / ↓ in intensity of the systolic murmur Occurs due to already compromised pulmonary blood flow as a result of severe hypoxia & metabolic acidosis

22. Investigation CBC with PBF Polycythemia Feature of iron deficiency anemia

23. Boot shaped heart(“ coeur en sabot”) : apex is lifted up, narrow base & there is a concavity in the region of pulmonary artery Normal heart size Oligaemic lung fields Hilar vessels are few, lung vessels also few X ray chest

24. ECG Right axis deviation RVH Tall peaked p wave may be present

25. The extent of aortic override of the septum Location & degree of the RVOT obstruction The size of pulmonary valve annulus The side of aortic arch Echocardiography

26. Cardiac catheterization Presence of multiple VSDs Degree &levels of stenosis in right ventricular outflow tract, pulmonary arteries, coronary artery anomaly.

27. Complication Hypercyanotic spell Cerebral thrombosis Cerebral abscess Infective endocarditis Hyperuremia & gout : 2ndary to polycythemia Relative iron deficiency anemia Bleeding disorder Coagulopathy

28. Treatment General measure Management of hyper cyanotic spell Surgery Treatment of complication Prophylaxis

29. Treatment depends upon the RVOT obstruction Severe tetralogy require urgent medical treatment & surgical intervention in neonatal period Less severe obstruction, stable & waiting for surgery Oxygenation Prevention of hypothermia I/V PG E 1 (.01-.02 micro/kg/min) Monitoring of blood glucose Oral propanolol (0.5-1 mg/kg every 6hr) Prevention/prompt treatment of dehydration Iron supplementation

30. Management of cyanotic spell 1.Knee chest position: Constriction of Femoral artery PVR left ventricular presser Rt - Lt shunt improves pulmonary blood flow better oxygenation & improves cyanosis Constriction of femoral vein venous return Rt - Lt shunt

31. It is difficult to achieve to knee-chest position. It is favorable to hold the child in parents shoulder with knees bent and oxygen is administered by another person from behind.  

32.   2. Oxygen:  Oxygen to improve oxygenation. It is better given in nebulized form . 3. Morphine: Depresses respiratory center→abolishes hyperpnea → decreases Systemic Venous Return. 0.2mg/kg SC. 4. IV fluids:  to correct dehydration 5. Inj NaHCO3: (1-2 meq /kg intravenously slowly). To correct metabolic acidosis

33.   6. Propanolol : 0.1-0.2 mg/kg I/V over 5 min. Reduces dynamic RVOT obstruction and slow the HR thereby decreasing R→L shunting. Increase SVR by antagonizing the vasodilating effects of   β2 adrenergic stimulation. 

34. 7. Phenylephrine Hydrochloride:  0.01 mg/kg IV (slowly) or 0.1 mg/kg SC or IM (Improve RV outflow, ↓R→L shunt 8. Ketamine :   0.25- 1.0 mg/kg. IV or IM→ has dual benefit causes sedation and ↑ SVR 9 . Premature attempts to obtain blood samples should be avoided.

35. Long Term  medical Management Educate the parents to recognize the spell and know what to do. 2. Oral propanolol therapy ,0.5-1.5 mg/kg every 6 hr Maintenance of good dental hygiene and practice of antibiotic prophylaxis against SBE are important.

36. Long Term  medical Management (cont’) 4. A relative iron deficiency state should be detected and treated. Hct values are usually normal so RBC indices and PBF should be monitored.

37. Surgical tratment

38. Surgical Palliative Shunt Procedures : -To increase pulmonary blood flow Indications: 1.     Neonates with TOF and pulmonary atresia . 2.     Infants with hypoplastic pulmonary annulus. 3.     Infants younger than 3-4 months with medically unmanageable hypoxic spells.

39.   Classic Blalock- Taussing shunt-(SA-PA) Modified  B-T shunt- A Gore-Tax interposition is placed between the Subclavian Artery and the ipsilateral Pulmonary Artery Potts operation- between the descending aorta and left PA.   Waterson Shunt-a between ascending aorta and right PA.

40. Corrective /Complete Repair Surgery:   Indications 1.     Oxygen saturation <75 to 80%. 2.     Occurrence of hypoxic spell 3.     Mildly cyanotic infants who have had previous shunt surgery 4.     Asymptomatic children with coronary artery anomalies.  

41.   Timing Symptomatic infants may have primary repair at 4-6months. Most  centers prefer primary elective repair by 1 to 2years of age .  The procedure include   - Patch closure of VSD   - Relief of RVOT obstruction by resecting obstructive muscle bundle  - And Pulmonary valvotomy Surgical mortality rate is <5%

42. Natural course/Prognosis Depends upon - Severity of RVOT obs - Associated other malformation - Management

43. NATURAL HISTORY 1 .    Infants with acyanotic TOF gradually become cyanotic. Patients who are already cyanotic become more cyanotic as a result of the worsening condition of the infundibular stenosis and polycythemia. 2.    Polycythemia develops secondary to cyanosis . 3.    Development of relative iron-deficiency state (i.e., hypochromia )

44. NATURAL HISTORY(contd.) 4 . Hypoxic spells may develop in infants 5. Growth retardation may be present if cyanosis is severe 6. Brain abscess and cerebrovascular accident rarely occur 7. SBE is occasionally a complication . 8. Some patients, particularly those with severe TOF, develop AR. 9. Coagulopathy is a late complication of a long-standing cyanosis.

45. The survival for untreated Tetralogy of Fallot is approximately 75% after the first year of life, 60% by four years, 30% by ten years, and 5% by forty years.

46. TOF with RVOT obstruction Clinical course Survival Mild Obstruction Cyanosis appear in childhood 3 rd -4 th decade Moderate Cyanosis since early infancy 2 nd -3 rd decade Severe Cyanosed since birth Seldom survive beyond 2 nd decade

47. Without surgery around 50% of children with TOF will die within the first few years of life and survival beyond 30 years is uncommon. With corrective surgery in childhood, survival is 95-99% , and almost all children can be expected to survive to adulthood.