Cardiac Surgery
Lec: 3Congenital Heart Diseases:-
Atrial Septal Defect :- An opening in the interatrial septum which leads to mixing of blood from pulmonary and systemic circulation. It is common and represent 7% of all congenital heart diseases, female to male is 3 to 1 . It can occur alone or together with other congenital heart diseases. It may be essential for life and sometimes created surgically.
Anatomical Classification:-
Ostium Secondom ASD :-in which the defect lies in the region of fossa ovalis, it represents 85% of ASDs.
Ostium Primum ASD :- in which the atrial communication is just above the mitral and Tricupid valve orifices and they are usually associated with a cleft in the mitral valve.
Sinus venosus ASD:- represent 10% of ASDs usually associate with anomalies of pulmonary venous return.
Natural History :-depends on 1.Type of defect, 2.Size of shun 3. Associated anomalies.
Pathophsiology:- ASD result in shunt of blood from left to right atrium producing excess pulmonary blood flow and increase cardiac work load ,this will lead to gradual increase in right ventricle pressure till it becomes equal to left side pressure and bidirectional shunt develop through different phases of cardiac cycle.
Clinical features:- The child is usually smaller than normal otherwise they are asymptomatic, as patient grow old they complain from palpitation, tachypnea, On auscultation afixed splitting of second heart sound and ejection systolic murmur can be heard in pulmonary area.
Diagnosis:-By echo which shows the type of defect and the direction of intracardiac shunt.
Manegement:-Spontaneous closure of ASD may occur but it is uncommon after 6 month age. Closure can be done either by surgery through median sternotomy and cardiopulmonary bypass using synthetic patch or by catheratization using umberella devise, usually this is better to be done for children at pre-school age.
PATENT DUCTUS ARTERIOSUS: Is a congenital anomaly caused by failure of closure of the duct which connects between the pulmonary artery and the aorta after birth, this will lead to excess flow of blood from aorta to pulmonary artery after reduction of high fetal level of pulmonary vascular resistance, symptoms depend on the size of duct, age at presentation and associated anomalies.
Clinical feature: In full term infant symtoms start at 6-8 weeks of life after reduction of pulmonary vascular resistance(PVR) which leads to shunt, while in premature infants symptoms begin in the 1st week of life due to presence of less smooth muscles in the pulmonary arterioles which lead to earlier reduction in PVR, commonest presentations are:-
Hyperactive pericardium and hyperdynamic circulation.
Bounding peripheral pulses with normal systolic BP and decreased diastolic BP.
Continuous machinary murmur in the pulmonary area .
In severe cases heart failure may develope and galloping rythm can be heard over pericardium
Diagnosis:By ECHO which shows the PDA and the associated anomalies.
MANEGEMENT:- Depends on age of patient and the presence of symptoms.
In premature infant prostaglandin inhibitor (indomethacin ) may be used with70 % success rate.
In full term symptomatic infant closure of the duct must be done , this is either done by catheterization or by surgery through left posterolateral thoracotomy through 4th intercostals space.
In full term asymptomatic infant closure of the duct can be delayed till 5 years old.
VENTRICULAR SEPTAL DEFECT: A hole in the interventricular septum may be single or multiple and it represent about 40% of all congenital heart diseases, it causes shunt of blood from left ventricle to right ventricle under high pressure.
Anatomical classification of VSDs depend on the site of the defect in the interventricular septum which is of two main kinds:
1.Perimemberanous VSD occur in the memberanous part of ventricular septum.
2. Muscular VSD occur in the muscular part of ventricular septum.
Clinical features:- depends on the size of VSD.
1.Small VSD may be asymptomatic or associate with few symtoms with small amount of left to right shunt of blood.
2. moderate size VSD usually asymptomatic at early life then they develope tachycardia ,tachypnea , inability to feed with more left to right shunt of blood .
3. large size VSD .infant usually develope congestive heart failure and failure to thrive with reccurent chest infection ,they may die at one year age, the huge left to right shunt will lead to increase in right side pressure which will end with pulmonary hypertention if it is not treated .
On Auscultation : apansystolic murmur is heared over the apex of the heart .
if right side pressure increase, right to left shunt may develope and the patient become cyanotic, here the intensity of murmur may decrease or may disappear.
Diagnosis :- By ECHO which shows the size and site of VSD, demonstrate the direction of intracardiac shunt and give idea about pressure difference between the two ventricles.
MANEGEMENT :VSD may be closed spontaneously the percentage of spontenous closure is inversely related to the age at which the patient is diagnosed.
Small asymptomatic VSD may be observed up to 10 year age waiting for spontaneous closre if not it must be closed surgically.
Moderat size VSD can be observed till 4 year age for spontaneous closure if not it must be closed .
Large VSD with huge shunt must be closed before 2 year age .
Closure is done by surgery through median sternotomy and cardiopulmonary bypass, usually the Right atrium is opened and the VSD is closed by a synthetic patch
TETRALOGY OF FALLOT:- Is congenital heart disease which presents with ventricular septal defect, overriding of the aorta to Right ventricle, hypertrophy of Right ventricle muscles and Right ventricle outflow tract obstruction, it may occur alone or with other conginetal heart diseases. symtoms depends on severity of malformation.
Infant usually present with cyanosis, tachypnea, they are usually small for age. on auscultation ejection systolic murmur can be heard over pulmonary area.
In sever cases cyanotic spells may develope and infant try to sequate to increase pulmonary blood flow
DIAGNOSIS:
1. Chest film shows narrow shadow of grate vessel in the superior mediastinum with classical boot shape heart .
2. ECHO can diagnose the anomaly and show direction of the right to left shunt MANEGEMENT:
It is better to repair the anomaly as early as possible before two year age , the urgency of operation is determined by the age symptoms at presentation ,in severe cases prostaglandin E1 can be used to keep ductus arteriosus open to increase pulmonary blood flow
Surgery is done by median sternotomy , cardiopulmonary bypass and total correction by closing the VSD and enlargement of right ventricle out flow tract together with resection of part of hypertrophied Right ventricle muscles.
Coarctation of Aorta: mean the presence of narrowing of the aortic arch usually distal to the site of insertion of ductus arteriosus and origin of left subclavian artery which leads to blood flow obstruction in the descending thoracic aorta., it represents 5-10% of congenital heart diseases, male > female.
Clinical Features: Symtoms usually develop after closure of ductus arteriosus, infants present with irritability, poor feeding, tachypnea while older children and adults present with symtoms of unexplained high blood pressure in the head and upper limbs in comparison to lower part of body, symtoms like headache, epistaxis, visual field disturbance may be present,
O/E- 1. asystolic murmur can be heard over left pericardium and in between the scapulae posteriorly. 2. arm-leg systolic BP gradient may be present. 3. Diminished femoral pulse with delayed upstroke.
4.bruit of enlarged collateral vessels around the coarctation may be heard at the infrascapular region.
Dx: 1. Chest film can show Cardiomegaly + Nothed ribs from enlarged tortuous intercostals arteries.
2. Angiography can show the site and extent of narrowing and collateral vessels.
3.Echo to exclude presence of other cardiac anomalies.
Mx: Is by Left Posteriolateral thoracotomy through 4th intercostal space, the narrow segment is resected and an appropriate size synthetic graft is used to bridge the defect.