Recent advances in the diagnosis and treatment of coarctation of the aorta

Right ventricular performance in congenital heart disease: a physiologic and pathophysiologic perspective

Underappreciated is the fact that the right ventricle is often the primary determinant of long-term morbidity and mortality in patients with congenital heart disease. Right ventricular performance in these patients depends on a unique set of physiologic and pathophysiologic factors that are rarely considered in acquired heart disease. This article explores this unique physiology and pathophysiology in the hope that it will enhance understanding of a wide variety of congenital cardiac anomalies.

Initial experience using the NuMED Cheatham Platinum (CP) stent for interventional treatment of coarctation of the aorta in children and adolescents

We report the immediate results in a group of selected patients with native or recurrent coarctation of the aorta who underwent endovascular stent implantation using the newly designed Cheatham-Platinum (CP)-stent. The balloon-expandable stents were implanted in 6 patients (mean age 12.7 years) with coarctation of the aorta (5 native, 1 recurrent). The maximal systolic peak pressure gradient was decreased from 49 to 3 mmHg (p <0.001). There was a 350% increase in the mean diameter at the original coarctation site (3.8 to 13.8 mm, p <0.01). Although the maximal diameter varied from 8 to 18 mm, there was only a minor reduction in the length of the CP-stents used (max. 11%). The dilatation was successful in all patients and there were no complications during balloon dilatation or stent implantation. All patients were hypertensive prior to stent implantation, with three of them requiring antihypertensive drug therapy. In 2 patients only a moderate dilatation diameter was chosen initially due to the extremely small coarctation site (1 mm) and repeat dilatation after 12 months was performed in order to obtain a maximal aortic diameter. At a mean of 18 months of follow-up, 5 of 6 patients are normotensive. There is no recurrence of coarctation, aortic dissection or aneurysm formation and no stent displacement. These findings suggest that the implantation of CP-stents for coarctation of the aortamay cover a wide spectrum of aortic diameters and consequently hereby offer an effective alternative approach to surgery or ballon dilatation alone even in infancy and childhood. The potential for redilatation of CP-stents in a wide range of diameters without significant shortening adds to the benefit of this device in growing children.

Surgically induced unilateral pulmonary hypertension: time-related analysis of a new experimental model

OBJECTIVE

Patients with irreversible pulmonary vascular obstructive disease caused by pulmonary hypertension due to congenital heart defects are considered either inoperable or only candidates to lung transplantation. This study evaluated an experimental model of surgically induced unilateral pulmonary hypertension.

METHODS

In eight pigs, 2-months-old, the left pulmonary artery was divided at the origin and end-to-side anastomosed to the descending thoracic aorta through a left thoracotomy. In this way, increased pulmonary blood flow in the right lung and systemic perfusion pressure and oxygenation in the left lung were obtained. After an interval of 6-12 weeks the animals underwent cardiac catheterization and were then sacrificed. Histological examination was done on both the lungs.

RESULTS

The mean left-to-right shunt through the left pulmonary artery diminished from 58.9+/-9.6% at the end of the procedure to 4.5+/-1.5% at the latest hemodynamic evaluation (P<0.01). Pressures and saturations remained identical in aorta and left pulmonary artery, without reduction (NS) with FiO(2)=1.0 ventilation; in the right pulmonary artery there was a mild elevation of the pressures, but still responsive (P<0.05) to FiO(2)=1.0 ventilation. Lung histology showed normal right pulmonary arteries, but irreversible vascular lesions like intimal fibrosis, medial hypertrophy, vascular occlusions, plexiform and dilatation lesions in all the left lungs.

CONCLUSIONS

The lung exposed to systemic pressure and oxygenation develops irreversible vascular lesions typical of pulmonary vascular obstructive disease. The lung exposed to increased flow shows only mild elevation of the arterial pressure, remains responsive to oxygen vasodilatation, and displays normal histology.

Severe pulmonary hypertension without right ventricular failure: the unique hearts of patients with Eisenmenger syndrome

Why adults with the Eisenmenger syndrome fare so much better than other patients with severe pulmonary hypertension is not known, but may be related to unique hemodynamics found only in these patients and in normal fetuses. We used echocardiography to evaluate ventricular morphology and function in 80 subjects: 45 cyanotic adults and 5 cyanotic adolescents with Eisenmenger syndrome, 10 infants with nonrestrictive ventricular septal defect and left-to-right shunt flow (pre-Eisenmenger phase), and 20 fetuses with structurally normal hearts. Cross-sectional morphology of the hearts was the same in all 4 groups with a flat ventricular septum throughout the cardiac cycle and equal thickness of the right and left ventricular free walls (regression slope 0.98, r = 0.97, p <0.0001). This morphology was the same in patients independent of age, defect type, and ventricular function. Right ventricular fractional area change was slightly inferior to that of the left ventricle but normal in most patients with Eisenmenger syndrome (0.47 +/- 0.14 vs 0.51 +/- 0.13, p <0.01). Overall, there was a highly significant linear relation between right and left ventricular function (r = 0.81, p <0.0001). The hearts of patients with Eisenmenger syndrome are more like normal fetal hearts than normal adult hearts. Because of the unique cardiovascular hemodynamics, regression of right ventricular wall thickness does not occur and is likely the reason that patients with Eisenmenger syndrome fare so much better than other adults with severe pulmonary hypertension.

The effects of congenital heart disease on the lungs

The alterations in anatomy and physiology, which often accompany congenital heart disease, may have a major impact on the child's lungs. These changes in pulmonary blood flow and ventilation are usually demonstrable on chest radiography and should be recognized as manifestations of the underlying lesion and not mistaken for primary lung disease. Correlation with the clinical history and physical examination are essential for correct interpretation, but radiological findings should be viewed objectively and without bias to provide accurate and valuable information to the treating physician.