Coarctation of The Aorta (COA)

5 – 7 % of CHD . Constriction of the Aorta of varying degree which may occur at any point from the transverse arch to the iliac bifurcation . M : F  2 : 1 . May be a feature of Turner syndrome . Associated with bicuspid Aortic valve in >70 % of cases

Types & Pathophysiology : Discrete juxtaductal obstruction ( adult type ). 98 % of cases . Occurs just below the origin of L subclavian artery , at the origin of Ductus Arteriosus . LV hypertrophy & LV HT . L  R Ductal shunting occurs following birth .

Preductal (infantile type ) : Tubular hypoplasia of transverse aorta , starting at one of the head &neck vessels & extending to Ductal area . RV  PDA  descending Aorta (R  L shunt ): palpable femoral pulse , differential cyanosis . Sever pul. HT & high pul. Vascular resistance & HF . BP  elevated in vessels proximal to coarctation . BP & pulse pressure  lower below coarctation . With time  collateral circulation (early adulthood)

Clinical Manifestations : After infancy , most patients are a symptomatic . Some children , adolescents weakness or pain (or both ) in lower extremities after exercise . HT on routine physical examination . Classic signs : Disparity in pulsation & BP in the arms & legs Weak or absent pulse(up to 40 % ) in LL , bounding in UL & neck , lower BP in LL relative to UL Radial – femoral delay .

90 % of patients have systolic HT in UL > 95th percentile for age . Precordial impulse &heart sounds are normal . Systolic thrill in supra sternal notch  bicuspid AS . Short systolic murmur along L sternal border at 3rd, 4th ICS well transmitted to L infra scapular area, neck. Murmur of AS  3rd R ICS . In older patients  systolic or continuous murmur heard L & R sides of chest laterally & Posteriorly associated with a palpable thrill .

In neonates or infants with sever COA : Sign of lower body hypo perfusion (differential cyanosis) . Acidosis & sever HF O/E  cardiomegaly systolic murmur , heard along L sternal border . loud S2 .

Investigations : CXR : finding depends on : Age , effect of HT , collateral circulation s Infants with sever COA  cardiomegaly & pul. Congestion . After 1st decade : Mild – moderate cardiomegaly ( LV) . Notching of inferior border of ribs (late childhood ). Descending Aorta has an area of post steno tic dilatation .

ECG : Neonates & young infants  R or biventricular hypertrophy . Young children  normal . Older patients  LV hypertrophy .

Cardiac Catheterization & selective L ventriculography &Aortography : Echo : Visualize the segment of coarctation , & look for associated lesion . Cardiac Catheterization & selective L ventriculography &Aortography : Visualization of collateral blood vessels .

Treatment : PGE2 infusion for neonates with sever COA & management of associating HF . Surgical repair soon after the diagnosis & stabilization of the general condition . Timing of surgery should not be delayed after 2nd decade because of associating LV dysfunction .

Prognosis & complications : CVA  severe neurologic damage or death. Premature coronary artery disease , HF , hypertensive encephalopathy , intracranial Hg  complication of HT . Infective endocarditis or endarteritis  adult Aneurysms of the descending Aorta & of collaterals . HF & hypo perfusion (life threatening ) . Complication of associating lesions . Abnormalities involving L subclavian artery .

Tetra logy of Fallot (TOF)

5 – 7 % of CHD . Consist of : Obstruction of RV outflow ( RV infundibulum, PS ) . VSD . Dextro position of the Aorta with Septal over –ride . RV hypertrophy .

Pathophysiology

Clinical Manifestations : In infancy : Mild RV outflow obstruction  HF ( L  R shunt across VSD ) with no cyanosis at birth . ( cyanosis occurs later in 1st year of life ). Sever degree of RV outflow obstruction  neonatal cyanosis , sever collapse following closure of Ductus Arteriosus .

Older Children : Cyanosis with dusky blue skin , gray sclerae & engorged blood vessels . Clubbing of fingers & toes . Dyspnea on exertion & tendency to squat . Paroxysmal hyper cyanotic attack ( hypoxic , blue or tet spells) : Common in 1st 2 years . Hyperpneic , restless , cyanosis increase , gasping respiration & syncope may result .

Occurs in the morning after initial awakening or after a vigorous crying . Lasts from few min. to few hrs., rarely fatal . Disappearance or decrease in the intensity of murmur Mild attacks  weakness & sleep . Severe attacks  unconsciousness , convulsion ,hemi paresis . Prolonged attacks  sever systemic hypoxia & metabolic acidosis . Growth & developmental delay .

Physical signs : precordial bulge with sub sternal impulse  RVH . Systolic thrill along L sternal border in 3rd &4th para sternal space . Systolic murmur : ejection in type at the upper sternal border , holo systolic at the lower sternal border . S2 either single or pulmonic component is soft. Continuous murmur in presence of collaterals .

Investigations CXR : ECG: Normal in size , boot shaped . Clear hilar & pulmonary vascularity (oligaemic lung ). R sided Aortic arch in 20-25 % of cases . ECG: RVH , P- pulmonale , RAD .

Echo : Cardiac Catheterizations :

Treatment : Aim  provides an immediate increase in pul. Blood flow to prevent the sequel of sever hypoxia . Lines of therapy : Maitainence of normal body temperature & blood glucose . IV administration of PGE  potent relaxant of Ductal smooth muscle . Prevention & prompt treatment of dehydration . Iron therapy : improves exercise tolerance & decrease the frequency of spells .

Oral propranolol decrease severity & frequency of hyper cyanotic spells . Surgical treatment as soon as spells begins . Palliative systemic –to-pulmonary artery shunt . ( Blalock – Taussig shunt ). Corrective open heart surgery . Treatment of hyper cyanotic spells : Placement of the infant on the abdomen in the knee – chest position . O2, rehydration, morphine (not > 0.2 mg/kg S.C ). Correction of metabolic acidosis  NaHCO3 . Drugs increasing systemic vascular resistance (phenylephrine, methoxamines) B-blockers .

Complications : Polycythemia & dehydration  cerebral thrombosis & CVA . Brain abscess . Bacterial endocarditis , HF unusual unless in pink TOF & following surgery . Growth retardation & pubertal delay . Complications of hyper cyanotic spells . Post – operative complications  chylothorax , diaphragmatic paralysis , Horner syndrome .