Academic‎ > ‎

INTERVENTIONS IN CONGENITAL HEART DISEASE

INTERVENTIONS  IN CONGENITAL  HEART DISEASE

         Dr.M.Zulfikar Ahamed, Professor of Pediatric Cardiology,SAT Hospital, Govt Medical College ,Thiruvananthapuram

The tremendous growth of infant and cardiac surgery and increasing role of catheter interventions in treating CHD, over the past two decades have made us reexamine the timing, need and mode of intervention in CHD. Fetal echocardiography has added another dimension to the evaluation process by enhancing and encouraging neonatal interventions – both catheter and surgical. The pharmacological and anesthetic advances have improved the surgical outlook for many young and malnourished infants. So it becomes obligatory on physician’s part to recognize the CHD, need for intervention if any and also to have reasonable consensus referral guidelines, following the detection of CHD.

            Generally, the decision and the time to operate a CHD depend on three factors.

1.                  Natural history of the lesion

2.                  Severity of the lesion

3.                  Available surgical centre

One has to weigh the potential complications of CHD in terms of CHF, growth failure, life threatening pneumonias, pulmonary hypertension, infective endocarditis and rarely sudden cardiac death and also problems related to hypoxemia such as spell, cerebral abscess and thrombosis against the potential of these lesions to close or become small.

In L -> R shunts and stenotic lesions one has to assess the hemodynamic severity of the defect and of course the nearest and likely available surgical centre also will exert its influence in timing of intervention.

DECISION TO INTERVENE

            Is based on

1.                  Symptomatic status

2.                  Noninvasive evaluation – echocardiography in particular

3.                  Invasive – catheterization and angiography

In selected cases MRI may be utilized in decision making, especially in Congenital Cyanotic Heart Disease (OCHD)

Symptomatic status is a useful guideline, but has severe limitations especially in obstructive lesions such as Aortic Stenosis or Coarctation of Aorta, most of which are asymptomatic in childhood. Even a moderate sized PDA or ASD need not be symptomatic. Currently the most widely sued mode of evaluation is color Doppler echocardiography which not only detects CHD and assesses the lesion both anatomically and physiologically, and has made cardiac catheterization unnecessary in most situations. Apart from providing the fine anatomical details, echocardiography often provides information on certain vital physiology like pulmonary pressures, gradients across obstructive lesions, flow ratios (pulmonary and systemic, valvar regurgitation etc.

Invasive studies are more often reserved for complex lesions and lesions where surgeons would require additional information on hemodynamics. Currently most of the VSDs and almost all PDAs and ASDs go to the surgeon without a catheterization. Even cyanotic lesions like TGA, TOF and Tricuspid Atresia can have surgery without catheterization. Catheterization as a diagnostic modality in CHD has given way to catheter interventions, which are procedure of choice in many CHD – PS, AS and often Coarctation of aorta. MRI is increasingly becoming popular in the diagnostic evaluation of CHD – especially in congenital cyanotic heart disease, vascular rings and other vascular defects such as Coarctation.                   

EARLY REFERRAL – RATIONALE

1.                  Simple correctable lesions which are hemodynamically severe like PDA, Coarctation and VSD may need early referral for surgery. The baby may succumb to either CHF or pneumonia, otherwise.

2.                  Neonatal severe obstructions – PS, CoA or AS can cause severe cardiac dysfunction and CHF and will require early intervention.

3.                  Ductus dependent lesions on either the right – pulmonary atresia or left side – HLHS, Severe complex Coarctation of Aorta are neonatal medical emergencies and will require some form of intervention.

4.                  Lesions which have tremendous pulmonary blood flow and propensity of PVOD (Pulmonary Vascular Occlusive Disease) like a large VSD, AV Canal Defect, AP window, TAPVC and TGA need be operated in infancy itself.

5.                  An adverse event like a cerebrovascular accident, brain abscess, spell and infective endocarditis calls for early attention.

We will discuss mode and timing of intervention after classifying the common lesions.

1.                  L -> R Shunt – VSD. PDA. ASD. AV Canal Defect.

2.                  Stenotic lesion – PS. AS. Coarctation of Aorta.

3.                  Cyanotic lesion – TOF. TGA. Tricuspid atresia.

Other lesions, management of which is briefly included are TAPVC, single Ventricle, and Ebstein etc.


Ventricular Septal Defect


            This is the commonest heart defect in the world, accounting for 25-30% of all lesions. Small VSD may close, as high as 50-75%. Moderate VSDs also close. Occasionally a large VSD can close but very rarely. If VSD can close, 60% do so by 3 years, 90% by 8 years. Decision has to be taken by clinical assessment (symptoms: CHF; Cardiomegaly and flow murmur), X-ray evidence of cardiac enlargement, pulmonary vascularity and PAH, ECG evidence of LV volume overload and RVH. Echocardiography is crucial in non invasive evaluation of CHD.

            Echocardiography looks at LV size, LA size and gives an impression of hemodynamic burden, assesses VSD size and evidence of PAH by calculating interventricular gradient (IVG). Higher the IVG, lower will be the PA Pressure.

1.                  Small VSD: VSD with no clinical or hemodynamic consequence with no PAH can be left alone. The shunt must be < 1:5:1.

2.                  Large VSD: VSD with CHF and growth failure should be treated aggressively with Digoxin, diuretic and vasodilators and trial of medical management can be tried up to 3 - 6 months. If child stabilizes, one can probably postpone surgery beyond 1 year when mortality may be less. If the trial of medical treatment fails, one has to intervene even prior to six months of age, with or without a catheterization.

3.                  Moderate VSDs can be given a trial of decongestives and carefully followed up to 2-3 years of life. If they continue to have significant shunt or PAH either by noninvasive evaluation or by catheterization, surgery has to be offered.

4.                  VSD with severe PAH: There are situations when VSD with severe PAH present to a clinician, when a catheterization is a must and indications for surgery are:

1.           Shunt of > 1.5 : 1

                   2.        Pulmonary Vascular Resistance (PVR) of < 10 wood unit

                   3.         PVR / SVR ratio is < 0.7.

 

Such situation often presents to the adult physician than to pediatricians. A careful decision must be taken with regard to operatability based on clinical cyanosis, ABG, non invasive data and of course catheterization data and properly weighing pros and cons of going for a high risk surgery.

            In asymptomatic child with VSD if shunt is > 1:8:1, surgery has to be undertaken while below < 1.5:1 surgery need not be done. A small percent of VSD (0.6%) may develop AR of varying grades, and if so needs surgery irrespective of shunt quantification, lest AR may prove progressive.

INDICATIONS FOR SURGICAL CLOSURE OF VSD

AGE

INDICATIONS

Under 6 MO

Uncontrolled CHF

6 – 24 MO

PAH or symptoms

Beyond 24 MO

QP : QS > 18.1

CONTRAINDICATIONS

PVR /SVR

> 0.7

QP : QS

< 1.5:1

PVR

> 10 wood units


ATRIAL SEPTAL DEFECT


     This is probably the commonest CHD after VSD and is often asymptomatic in childhood. Symptoms appear by 20-30 years and Pulmonary appear by 20-30 years and Pulmonary Vascular Occlusive Disease (PVOD) can occur in 15% of adults. Spontaneous closure of even smaller ASD are rare beyond 3 years.

            Secundum ASD does not generally require catheterization prior to surgery. A good Transthoracic each will provide all the information required. Sinus venosus ASD may either require a trans esophageal echo or even a catheterization. Elective repair or ASD is done between 3 and 5 years of life. Surgical mortality is near zero.

 If child with a ASSD is catheterized the indication for intervention is

1.                  QP : QS > 1.5:1

2.                  PVR – Normal

Surgery involves cardiopulmonary wither direct suture or patch. Repair of sinus venosus ASD would require a patch to redirect to right upper pulmonary vein into left atrium.

If ASD presents with severe PAH, which is quite rare in child hood, the decision to operate would be based on cath data.

                        QP : QS : > 1.5:1

                        PVR: < 6 Wood units

                        PVR / SVR : < 0.5

            Before 11 years, the results of ASD closure are excellent while beyond 11 years, it is good but not excellent. After 25 years, ASD closure still confers better survival, but overall result is only fair.

            Recently device closure has become popular in ASD particularly in small to moderate ASDs where one would not risk use of CPB. Various devices have been introduced. Nearly 40 % of Secundum ASD will be amenable to device closure. Presently Amplatzer Device is the one which is most popular. Other devices used are ASDOS, Cardioseal etc.

AV SEPTAL DEFECT (AVSD)

OSTIUM PRIMUM ASD

            If there is No VSD and minimal LT AV valve regurgitation, surgery is indicated between 3-5 years if shunt is > 2:1 or cardiomegaly is present. Early surgery is indicated if child is symptomatic and has significant Left AV valve regurgitation.

COMPLETE AVSD

            Complete AVSD without PS has pulmonary pressures near systemic levels and hence is operated in infancy, usually around six months, preferably by 3 - 4 months for fear of developing PVOD (Pulmonary Vascular Occlusive Disease). Even though severe PVOD as detected by catheterization is a contra indication to surgery, one should be cautious not to over diagnose PVOD in infants below 2 years. One repairs the AV valve (S) and closes the ASD and VSD.

            A two stage approach including pulmonary artery banding followed by repair later was initially favored but has given way to one stage repair recently.

            The surgical mortality in AVCD repair is between 3-10%


PATENT DUCTUS ARTERIOSUS (PDA)

A. PDA in a preterm

            Trial of indomethacin or ibuprofen may be undertaken and if it fails, surgery is indicated.

B. Large PDA

            Surgery is recommended in infancy if there is significant CHF, growth failure or severe PAH, even though post operative morbidity may be high.

C.  Asymptomatic or mildly symptomatic PDA

            Surgery can be done at any age beyond 12 months electively, preferably by 1 - 2 years. Even asymptomatic PDA should be operated as there is a continuing risk of infective endocarditis, throughout life and there is virtually no mortality in elective PDA ligation.

            Wide, short Ductus is managed by division and suture, while narrow PDA is managed by triple ligation.Surgical mortality is nil,

            Recently catheter closure by coils has become quite popular – (Gianturco coils) and is preferred by many cardiologists and parents. A new device, though costlier (Amplatzer device) has also become popular in many centers. These devices obviate the need for surgery and scar, and are almost always curative.

          Children may present with color Doppler detected PDA without a murmur. The duct may be so small that it may not need closure

PULMONARY STENOSIS

            PS is divided into mild (gradient across pulmonary valve < 40 mmHg), moderate (gradient 40-80 mm Hg) and severe (gradient >80 mmHg).

            a. Mild PVS : Has a benign course and requires no intervention. They need Doppler follow up periodically to see if stenosis progresses; which they seldom do.

            b. Moderate – severe PS: Will need intervention as a semi elective procedure.

            Balloon Pulmonary Valvotomy is the procedure of choice and is done before school entry. The long term benefit is quite remarkable. Mortality is virtually non existent. The cure rate is 95 % .

         c. Neonate with critical PS: Will need emergency balloon Valvotomy once the baby is stabilized with O2, Inotrope and PGEI, The results are quite good but with increased morbidity.

 

AORTIC STENOSIS (AS)

            Valvar AS is not as benign as PS. The classification of AS is all follows – based on transvalvar gradient.

                        < 25 mm Hg               -           Trivial

                        25-50 mmHg             -           Mild

                        50-75 mmHg             -           Moderate

                        > 75 mmHg                -           Severe

 

Trivial AS:      No specific therapy: No limitation of activity. Yeary  Doppler

                        follow up looking for progression.

Mild AS:         Some restriction of Activity

                        Echocardiography yearly

                        Cath – if symptoms / ECG changes

Mod AS:         Restriction of activity

 

            Intervention is decided on the basis of symptoms / ECG changes / Exercise ECG. A catheter gradient of above 75 mmHg is  indication for balloon Valvotomy.

            Severe AS: Needs intervention even without symptoms or ECG changes.

Options

1.                  Balloon Aortic Valvotomy – is preferred in childhood (BAV)

2.                  Surgical Valvotomy

The mortality is < 0.5 %

COARCTATION OF AORTA (COA)

1.         Elective intervention – Between 18 months and 36 months.

            Procedures may include

a.      Resection and end to end anastamosis

b.      Resection and use of tubular prosthesis

c.      Subclavian flap angioplasty (< 2 years)

Mortality ranges from 0 to 3%. Of late balloon dilatation of CoA has been found to be reasonably successful with efficacy comparable to surgical result. However its long term results and problems are yet to be sorted out. It can be offered to older children and young adults with additional stent deployment


TRANSPOSITION OF GREAT ARTERIES (TGA)


            TGA in a new born is often a medical emergency which has to be palliated with PGEI, and often which balloon atrial Septostomy.

Balloon Atrial Septostomy (BAS)

            It is indicated in severely hypoxemic neonates and occasionally it is feasible to do BAS even beyond 1 month of life. It involves putting across the PFO a dye fluid filled balloon and tearing IAS so that mixing improves. Saturation improves and leads to better survival in infancy. Later on they can be taken up for definitive surgery. However many centers now prefer to send the baby with TGA directly for definitive surgery supported by PGE infusion without BAS.

Definitive Surgery

a.                  Senning (Atrial switch) – “Physiological”

b.                  Jatene (Atrial switch) – ASO – “Anatomical”

A.        Senning

            Is usually done between 4 and 9 months of life where pulmonary venous blood is rerouted across the tricuspid valve and systemic venous blood enters LV via mitral valve and reaches pulmonary artery RV supports aortic circulation.

B.        Arterial Switch Operation (ASO)

            It is more logical and is now preferred in TGA with intact septum. But this should be performed within 3 weeks of life as Left ventricle may regress and may not be able to support aorta later. In ASO and pulmonary artery are transected and anastomosed and switched i.e. distal aortic segment to proximal PA (Neo-aorta) and distal PA to proximal aortic stump and coronaries are transferred to neo aorta. Here RV supports the PA and LV supports the aorta and is more physiological.

C.        Rastelli

            It is the procedure of choice in TGA-VSD PS where there is an intraventricular repair with placement of extra cardiac conduit between RV and PA. Many babies may need a palliative BTS prior to the definitive repair.

TGA - Surgical Options / Timing

1. TGA. IVS

Senning

ASO

4-12 month

< 3 week

2. TGA.  VSD

Senning+ VSD Closure

ASO + VSD Closure

Infancy

< 4 weeks

3.  TGA. VSD.  PS

Rastelli

(may need a BTS prior to Rastelli

2-4 years

  

                   TRICUSPID ATRESIA

 

Management in Infancy

 

            Supportive management with  O2, PGEI, infusion or BAS. Palliation  by BT shunt (< 4 months) Bidirectional Glenn (> 4 months).

            BTS can be offered beyond 4 months also. Glenn involves an end to side anastamosis of superior vena cava to Right Pulmonary Artery (RPA).

 

Elective Surgery

            Involves Fontan or TCPC (Total Cavo Pulmonary Connection) Fontan consists of Rt atrial to main pulmonary artery direct anastamosis or conduit and by passes Rt ventricle. Concept of TCPC is more recent where there is a cavo (IVC and SVC) pulmonary connection by which systemic veins directly communicate with Pulmonary Artery.

            The usual age of surgery is 2 - 12 years and child should have normal PA pressures and normal PVR (< 4 Wood units).

 

EBSTEIN ANOMALY

            It is uncommon in childhood and its management depends on time of presentation.

            Infants with hypoxemia – BT shunt or Bidirectional Glenn . Starnes operation is offered in a sick Ebstein.

            Recently in some infants, TCPC has been tried in Ebstein.

            Older child / adult – TV replacement – reconstruction with placation of atrialized portion of RV (Danielson’s repair).

 

Indication  for Surgery are

1.                  NYHA III  IV Symptoms

2.                  Progressive cardiomegaly or cyanosis

 

TAPVC

            Surgery is offered as soon as diagnosis is made .Child may not even need a catheterization. The supracardiac type is managed by creation of a wide anastamosis between LA posterior wall and anterior part of vertical vein. The ascending vertical vein ligated and PFO / ASD is closed.

            Obstructed TAPVC will have higher mortality but of late improved techniques have improved survival.

 

SINGLE VENTRICLE (SV)

Palliation :      SV with PS –    BT shunt or Glenn

                        SV with PAH – Banding of PA

Definitive:       1. Fontan or TC PC

                        2. Septation operation – in order child with moderate PAH

    Where  TCPC / Fontan is not suited.

 

TRUNCUS ARTERIOSUS

            Initially pulmonary banding was done to prevent PVOD and palliative and then elective repair was done later. Recently primary repair is being attempted by removing PA from Truncus, closing the VSD and continuity between RV and PV being established by a cryo preserved homograft.

 

What intervention in CHD does to a child ?

            When a CHD undergoes an intervention, early mortality, morbidity, need for redo surgery and longevity are of concern. Based on these parameters we can categorize CHD into various subsets.

 

1. Cure                                   -           PDA

2.  Near  cure                         -          ASD.  PS. Coarctation .TAPVC

3.  Excellent Result                -           VSD.  TOF .

4.  Good Result                     -           AVSD. Tricuspid  Atresia. TGA.

5.  Fair Result                        -           Truncus.  DORV ,Ebstein. Single Ventricle.

                                                         

 References

1.                  Mcdaniel NL, Gutgesell HP, Ventricular Septal Defects in Moss & Adams’ Heart Disease in Infants, Children and Adolescents Sixth Edition. Ed. by Allen HD, Gutgesell HP, Clark EB, Driscoll DJ. Lippincott. Williams and Wilkins 2001 : 627.

2.                  Garson A, Bricker JT, Fisher DJ, Neish SK Ed. Science & Practice of Pediatric Cardiology 2nd Edition Williams & Wilkins 1996.

3.                  Alpert BS, Cook DH et al. Spontaneous closure of small VSD. Ten year follow up Pediatrics 1979; 63: 204-206.

4.                  Rocchini A< Lock JE Defect Closure – Umbrella devices in Diagnostic and Interventional Catherisation in CHD.  Ed Lock JE, Keane JF, Perry SB Boston Kluver 200: 179.

5.                  Freed M The Pathology, pathophysiology, recognition and treatment of CHD in Hurst’s The Heart 10th edition. Ed Fuster V, Alexander RW, O Rourke RA McGraw Hill 2001: 1837.

6.                  Ramanarayan PV When should pediatricians be referring clinical problems to cardiac surgeons? In Pediatric Cardiology – Pulmonary Update 99 Ed Zulfikar MA, 1999 : 92.

7.           Krishnakumar R, R, Radhakrishnan S Transcatheter treatment for CHD – Part I & II in Progress in Pediatric Cardiology, Division of Pediatric Cardiology 2000.                                                         

Comments