Basic evaluation of grown up congenital heart disease (GUCH)
Evaluation of a patient with grown up congenital heart disease (GUCH) is similar to any other patient and begins with a good history to assess the present and past symptoms. Intercurrent events have to be noted as well as any previous need for changes in medication. Changes in life style and daily activity will be helpful in assessing disease progression. Clinical evaluation would include documentation of blood pressure, auscultatory findings and any signs of heart failure. This is important for follow up evaluations. Routine electrocardiogram and pulse oximetry are done in the hospital setting. Chest x-rays, though not routinely indicated now, is often useful in the documentation of cardiac size, configuration and pulmonary vascularity which is helpful during long term follow up.
Echocardiography is currently the most important investigation in GUCH. Cardiac anatomy including position, orientation, sequential chamber analysis (venous return, atrioventricular relationship and ventriculo arterial relationship) are documented with echocardiography, it may be quite a time consuming process in complex congenital heart diseases. But in GUCH, the number of possibilities become limited due to the natural attrition of some of the more complex varieties which could be seen in early infancy. Cardiac chamber morphology and function, valvular morphology and function as well as shunt lesions can be quantified by echocardiography. Quantification of transvalvar flows and gradients can be done with Doppler echocardiography. Difficulties in assessment of ventricular volumes may be experienced in complex anatomies. Doppler gradients can be erroneous when the alignment of the jet is inaccurate and in case of stenoses in series. In certain cases great vessels may not be imaged well and so may be the venous return.
Role of cardiac magnetic resonance imaging (CMR) in the evaluation of GUCH
Cardiac magnetic resonance imaging (CMR) has the advantage that it is less operator dependent than echocardiography regarding the acquisition of images. But when it comes to interpretation, experience does matter a lot in delineating the potential permutations and combinations possible in congenital heart disease. Three dimensional reconstruction enables better visualisation of the cardiac anatomy. Unlike echocardiography, CMR is not restricted by the echo window, which is often a limitation for the acquisition of echocardiographic data. But echocardiography is superior to CMR in estimating gradients and in detecting small highly mobile structures like vegetations. Quantification of ventricular volumes, ejection fractions and valvular regurgitations can be done by CMR. Evaluation of right ventricular volumes and ejection fraction are better done with CMR than echo because of the complex shape of the right ventricle. CMR is useful in the evaluation of right ventricle to pulmonary artery conduits, branch pulmonary arteries, aorta, systemic and pulmonary veins and collaterals. Detection and quantification of myocardial fibrosis with late gadolinium enhancement is another advantage of CMR. Tissue characterisation for fat and iron is also feasible with CMR. Though coronary anomalies can be detected by CMR, computerised tomographic (CT) angiography is superior for this purpose. Intracardiac and extra cardiac masses can be delineated well by CMR.
Role of computed tomography (CT) in GUCH
Computed tomography (CT) provides excellent spatial resolution and has a rapid acquisition time. It is good for imaging arteries and veins. CT is superior to cardiac magnetic resonance (CMR) imaging for visualising the epicardial coronary arteries, their collaterals and arteriovenous (AV) malformations. CT can also be used to assess the size of the ventricles and their function, but has an inferior temporal resolution compared to cardiac magnetic resonance imaging. As it is well known, the major drawback of computed tomography is the radiation risk, which cannot be avoided. Contrast related issues like the small but real potential for contrast nephropathy, allergic reactions, transient myocardial suppression and thrombotic possibility in a dehydrated polycythemic patient should also be given due consideration.
Indications for cardiac catheterisation in GUCH
The role for cardiac catheterisation in congenital heart disease has come down remarkably with the wide availability of echocardiography, cardiac magnetic resonance (CMR) imaging and computed tomography (CT). Still there are some reasons to go for a cardiac cath in congenital heart disease. When non invasive assessment has shown a pulmonary artery systolic pressure above 50 mm Hg, there is a role for cath to assess the pulmonary vascular resistance in shunt lesions. Pulmonary vasoreactivity can also be tested to assess the reversibility of pulmonary hypertension, with oxygen or nitric oxide, the latter being preferable now. Ventricular function, pressure gradient and shunt quantifications may be additional roles for cardiac cath when the non invasive values are equivocal. The need for coronary angiography in men over forty years and post menopausal women going for cardiac surgery and in those with signs or risk factors for coronary artery disease is another potential role. Angiography is also useful in the evaluation of collaterals.
Special problems in cyanotic congenital heart diseases with natural survival to adulthood
The important congenital heart diseases with cyanosis who survive without the possibility of a therapeutic intervention into adulthood are Eisenmenger syndrome, univentricular heart, Ebstein’s anomaly of the tricuspid valve. Though these individuals have a serious symptomatic cardiac problem, surgical risk is often higher than that of the natural history. Heart lung transplantation and single lung transplantation with surgical correction of the cardiac lesion may be the option in some of these cases, though with a lot of associated problems and logistic issues. Many of these patients have serious complications like profuse hemorrhage (hemoptysis), infective complications like cerebral abscess and sometimes endocarditis, tachyarrhythmias like atrial flutter and fibrillation or thromboembolic episodes. Some have symptoms due to hyperviscosity which may require venesection for relief. But venesection can lead on to a vicious cycle with decompensated erythrocytosis. This is because renal ischemia leads to enhanced erythropoetin secretion which causes an increase in the red cell mass. Several of these patients can remain stable, of course with effort intolerance. But the balance tilts unfavourably in situations like pregnancy, intercurrent illnesses or surgical procedures. They can also worsen following dehydration and exercise or even some medical interventions. Complications may need procedures like embolization of bleeding vessels in case of severe hemptysis, neurosurgical drainage of brain abscess, mapping and ablation of cardiac arrhythmias etc.
Congenital heart disease which require intervention in adults
By and large the major group of patients who require interventions for congenital heart disease in adult life would be those with atrial septal defects. This is so because they will be asymptomatic and may be detected only in adult life during routine evaluation. Unlike ventricular septal defects, they seldom develop irreversible pulmonary hypertension by adulthood and are amenable to device closure or surgery. Next common congenital heart disease which may require intervention in adult life would be valvar aortic stenosis, followed by coarctation of aorta, valvar pulmonary stenosis, patent ductus arteriousus and ventricular septal defect. The last two are more often corrected earlier in childhood or have already developed irreversible pulmonary hypertension by the time they reach adulthood so that the number which go for primary intervention in adults is lower.