Preoperative measurement of pulmonary vascular resistance in complete transposition of the great arteries

Surgical strategies for patients with congenital heart disease and severe pulmonary hypertension in low/middle-income countries

In this review, we discuss specific surgical strategies that are used in patients with congenital heart disease and severe pulmonary arterial hypertension. Our own experience, with the use of unidirectional valved patches in managing these patients, is also discussed in detail.

Arterial switch operation with unidirectional valved patch closure of ventricular septal defect in patients with transposition of great arteries and severe pulmonary hypertension

OBJECTIVE

For patients with dextro-transposition of great arteries (d-TGAs), ventricular septal defect (VSD), and severe pulmonary arterial hypertension (PAH), the common surgical options are palliative arterial switch operation (ASO) or palliative atrial switch operation leaving the VSD open. We evaluated the role of ASO with VSD closure using a fenestrated unidirectional valved patch (UVP).

METHODS

Between July 2009 and February 2011, six patients with TGAs, VSD, and severe PAH (mean age 39.8 ± 47.4 months, median 21, range 8-132 months), weighing 10.7 ± 9.2 kg (median 8.6, range 4.3-29 kg), underwent ASO with VSD closure using our simple technique of UVP. Mean pulmonary artery systolic pressure before the operation was 106 ± 12.7 mm Hg (median 107.5, range 95-126 mm Hg) and pulmonary vascular resistance was 9.5 ± 4.22 units (median 9.5, range 6.6-17.1 Wood units).

RESULTS

There were no deaths. All patients had a postoperative systemic arterial saturation of more than 95%, although there were frequent episodes of systemic desaturation due to right-to-left shunt across the valved VSD patch (as seen on transesophageal and transthoracic echocardiograms). Mean follow-up was 10 ± 7.6 months (median 7.5, range 1-22 months). At most recent follow-up, all patients had systemic arterial saturation of more than 95% and no right-to-left shunt through the VSD patch. In one patient, the follow-up cardiac catheterization showed a fall in pulmonary artery systolic pressure to 49 mm Hg.

CONCLUSION

Arterial switch operation with UVP VSD closure is feasible with acceptable early results. It avoids complications of palliative atrial switch (arrhythmia and baffle obstruction) and partially or completely open VSD.

Assessment of operability in d-transposition of great arteries with ventricular septal defect: A practical method

Introduction:

Pulmonary vascular disease is a risk factor in the surgical management of patients with d-transposition of great arteries (d-TGA) and a ventricular septal defect (VSD). In older infants or children with this physiology, the question of operability often arises. Cardiac catheterization in this condition can be fallacious. It is well known that oxygen reduces pulmonary arterial pressure and pulmonary vascular resistance especially where irreversible pulmonary vascular obstructive disease has still not set in. We tried to implement this effect of oxygen in correlation with echocardiography in patients with TGA-VSD physiology where operability was in question.

Methods:

Patients with d-TGA and a large post tricuspid shunt in whom operability was considered doubtful were selected for the study. We administered humidified oxygen at the rate of 10 litres/minute by mask for 48 hours in the ward or intensive care unit. After administration of oxygen we reassessed the child echocardiographically looking for signs of lowering of pulmonary vascular resistance which included increased pulmonary venous blood flow to the left atrium (LA) and right to left shunting across the VSD.

Observation:

We studied 1 patient with d-TGA and aortopulmonary window (APW), 4 patients with TGA / large VSD and 1 patient with Taussig-Bing anomaly. The age of the studied children ranged from 4 months to 3 years with a mean age of 1.1 years. After administering oxygen as described, echocardiogram showed an increase in pulmonary venous blood flow to the LA and right to left shunting across the VSD in 5 patients and increased flow reversal in aorta in presence of the APW.

Conclusion:

Patients with TGA/VSD physiology with doubtful operability can be subjected to this method of determining operability using echocardiography after administering oxygen. Although not 100% accurate in predicting long term postoperative pulmonary hypertension, this is a simple, noninvasive method that can aid in decision making in such a situation.

Unidirectional valved patch closure of ventricular septal defect with arterial switch operation in a patient with d-transposition of great arteries with severe pulmonary hypertension

We report our experience with a five-year-old child with d-transposition of great arteries (d-TGA), ventricular septal defect (VSD), and severe pulmonary arterial hypertension (PAH). A fenestrated unidirectional-valved patch was used to close the VSD and a standard arterial witch operation (ASO) was performed. Difficulties in assessment of operability and the choice of procedures in such patients are briefly discussed.

Effect of the oral endothelin antagonist bosentan on the clinical, exercise, and haemodynamic status of patients with pulmonary arterial hypertension related to congenital heart disease

OBJECTIVE

To evaluate the clinical, exercise, and haemodynamic effects of chronic oral administration of the non-selective endothelin receptor antagonist bosentan on patients with pulmonary arterial hypertension (PAH) related to congenital heart disease (CHD).

DESIGN

Prospective non-randomised open clinical study.

SETTING

Cardiology tertiary referral centre.

PATIENTS

21 patients with a mean (SEM) age of 22 (3) years with chronic PAH related to CHD (15 with Eisenmenger's syndrome). Patients were in World Health Organization (WHO) class II to IV with oxygen saturation 87 (2)%.

INTERVENTION

Patients underwent clinical, exercise, and haemodynamic evaluations at baseline and after 16 weeks of treatment.

RESULTS

Bosentan improved (p < 0.01) WHO class, peak oxygen consumption from 16.8 (1.4) to 18.3 (1.4) ml/kg/min, exercise duration from 9.0 (0.8) to 10.7 (0.6) minutes during the treadmill test, walking distance from 416 (23) to 459 (22) m, and Borg dyspnoea index from 2.8 (0.2) to 2.0 (0.1) during the six minute walk test. Bosentan treatment improved (p < 0.05) mean pulmonary artery pressure from 87 (4) to 81 (4) mm Hg, pulmonary blood flow index from 3.2 (0.4) to 3.7 (0.5) l/min/m2, pulmonary to systemic blood flow ratio from 1.2 (0.2) to 1.4 (0.2), and pulmonary vascular resistance index from 2232 (283) to 1768 (248) dyn.s.cm(-5). Two patients died, presumably of arrhythmic causes, who were in WHO class IV at baseline and who had improved during treatment.

CONCLUSIONS

Bosentan induces short and mid term clinical, exercise, and haemodynamic improvements in patients with PAH related to CHD. Larger studies with long term endothelin receptor antagonism are needed to assess the safety and possible treatment role of bosentan in this population.

The diagnostic evaluation of patients with complete transposition

SummaryThe vast majority of patients with complete transposition present during either the neonatal period or early infancy. Almost always the diagnosis and the categorization of associated lesions can be established by cross-sectional echocardiography. Doppler techniques usually provide enough information about flows to allow palliative or radical surgery to be undertaken without formal cardiac catheterization, because balloon atrial septostomy is carried out with echocardiographic imaging, often on the intensive care unit. Angiography is occasionally performed to visualize the pulmonary arteries or the aorta, and, if there is suspicion of a significant elevation of the pulmonary vascular resistance, it must be measured at cardiac catheterization. Neither cross-sectional echocardiography nor aortography is entirely reliable in identifying those patterns of the coronary arteries which are a contraindication to the arterial switch operation. There is, as yet, no evidence that either magnetic resonance imaging or transesophageal echocardiography are superior to more conventional methods of preoperative diagnosis in complete transposition and it seems unlikely that they will be required.