Percutaneous pulmonary artery and vein stenting: a novel treatment for mediastinal fibrosis.

Mediastinal fibrosis is a rare consequence of infection with the fungus Histoplasma capsulatum that can lead to occlusion of large pulmonary arteries and veins and mainstem bronchi. Medical and surgical treatments for this disorder have been ineffective. We describe successful treatment for central pulmonary arterial and venous obstruction due to mediastinal fibrosis in four patients using percutaneously placed intravascular stents. Patients were severely limited, World Health Organization functional class III or IV. At the time of right and left heart catheterization, stents were placed in pulmonary arteries (n = 1), veins (n = 2), or both (n = 1) to relieve vascular obstruction resulting from mediastinal fibrosis. Immediate hemodynamic and clinical improvement was observed in all patients. Three of the four patients have had sustained improvement in exercise tolerance, from 3.5 mo to 4.5 yr after stent placement. The only complication was a self-limited pulmonary hemorrhage in one patient. Our initial experience suggests that percutaneous stent placement to relieve central pulmonary arterial or venous obstruction due to mediastinal fibrosis is an effective new treatment modality.

Percutaneous stent placement as treatment for an infant with superior vena cava syndrome.

The percutaneous use of stents for the treatment of superior vena cava (SVC) syndrome is well described in the adult population. We report the successful use of intravascular stents to treat an infant with severe SVC syndrome.

Relief of right ventricular to pulmonary artery conduit stenosis using a self-expanding stent.

Intravascular stents have recently been used to treat vascular stenoses in congenital heart disease. Size limitations, however, may preclude their use in certain situations. We describe the successful relief of right ventricular to pulmonary artery conduit stenosis in an adult patient late after repair of truncus arteriosus using a larger, self-expanding wall stent.

Pulmonary vein stenosis after catheter ablation of atrial fibrillation.

BACKGROUND: This report describes the complication of pulmonary vein stenosis with resultant severe pulmonary hypertension that developed in 2 patients after successful catheter ablation of chronic atrial fibrillation. METHODS AND RESULTS: Three months after successful catheter ablation of atrial fibrillation, both patients developed progressive dyspnea and pulmonary hypertension. Both were found to have severe stenosis of all 4 pulmonary veins near the junction with the left atrium. Balloon dilation of the stenotic pulmonary veins was performed in these patients, with improvement in dyspnea and pulmonary hypertension. CONCLUSIONS: The complication of pulmonary vein stenosis is potentially life-threatening, and the application of radiofrequency current within the pulmonary veins with standard catheter technology should be avoided. This complication can be treated with balloon dilation, although the long-term course is unknown.

Transcatheter closure of the patent ductus arteriosus: a comparative study between occluding coils and the Rashkind umbrella device.

This study was performed to evaluate the efficacy of transcatheter coil closure of the patent ductus arteriosus in comparison to our experience with the Rashkind umbrella device. Transcatheter coil closure of the patent ductus arteriosus has been reported with encouraging results. We present our experience with ducti up to 5.0 mm in diameter and report the short-term follow-up. We compare the results with our previous experience with the Rashkind umbrella device. Seventy-one patients underwent transcatheter coil closure. Median age was 3.1 years, and median weight was 13.6 kg. Mean ductus diameter was 2.0 +/- 1.1 mm. These were compared with 105 patients who underwent transcatheter closure using a single Rashkind umbrella device. The median age was 3.2 years and the median weight was 14.0 kg. The mean ductus diameter for this group was 2.1 +/- 0.6 mm. The ductus murmur in the coil group disappeared in all patients. Immediate (< or = 24h), complete closure was achieved in 89% of the coil group as compared to 71% for the Rashkind umbrella device group (P < 0.005). Closure rate for the coil group was 97% at the 6-month follow-up, vs. 82% for the Rashkind umbrella device group at the 6-12 month follow-up (P < 0.05). In almost all patients requiring more than one coil, the ductus was crossed serially from the aortic end. All patients with ductus diameter > or = 3.0 mm required two or more coils. Eleven coils in six patients embolized to the pulmonary arteries. All coils except one were retrieved with subsequent successful foil placement. Sixty-seven patients (94%) in the coil group were discharged in < or = 24 h. Transcatheter closure of the patent ductus arteriosus using multiple coils is a more effective technique than the Rashkind umbrella closure and has excellent short-term results. This can be performed safely as an outpatient procedure.

Effect of Na+ and K+ channel blockade on baseline and anoxia-induced catecholamine release from rat carotid body.

Ionic membrane currents are hypothesized to play a major role in determining secretion from carotid body glomus cells, and increased secretion likely mediates the increase in nerve activity in response to hypoxia. The hypothesis that Na+ and K+ channels play an important role in determining secretion and nerve activity was tested by measuring single-fiber afferent nerve activity along with an estimate of free tissue catecholamine using Nafion-covered carbon-fiber micro-electrodes placed in rat carotid bodies in vitro. Baseline and anoxia-stimulated (1 min duration; PO2 of approximately 0 Torr at nadir) levels were quantified. Sham treatment had no significant effect. Tetrodotoxin (2 microns) ablated the nerve activity and reduced peak catecholamine (19.5 +/- 3.1 to 14.5 +/- 3.4 microM; P < 0.05). Cesium (10 microns) had no effect on catecholamine but reduced the nerve response (19.8 +/- 2.7 to 7.8 +/- 2.0 Hz; P < 0.05). 4-Aminopyridine (4 mM) significantly reduced the nerve response (17.2 +/- 3.7 to 4.9 +/- 1.9 Hz; P < 0.05) and increased the baseline (0.9 +/- 0.2 to 3.1 +/- 0.8 microM; P < 0.05) and reduced the peak catecholamine (10.0 to 4.3 +/- 0.8 microM; P < 0.05) levels. These results demonstrate that Na+ and K+ channels play an important role in modulating the secretory and nerve responses. However, channel blockers do not emulate severe hypoxia, suggesting that hypoxia transduction procedes, at least in part, through an alternate pathway.

Developmental changes in hypoxia-induced catecholamine release from rat carotid body, in vitro.

1. Developmental changes in free tissue catecholamine levels were studied using Nafion-coated, carbon fibre electrodes placed in rat carotid bodies, in vitro. Simultaneously, single fibre chemoreceptor afferent activity was recorded from the sinus nerve. Five age groups were examined: 1, 2, 6, 10 and 20-30 days of age. 2. Using fast-scan voltammetry, similar current peaks were observed during exposure to exogenous dopamine and during superfusion with hypoxic saline. This suggests that changes in carbon fibre electrode current are due to an increase in free tissue catecholamines. 3. Baseline catecholamine levels were significantly less in the 1-6 day age groups compared to 10 day and 20-30 day rats. 4. During 1 min of hypoxia the peak concentration of tissue catecholamine was significantly less in the 1 day compared to the 2 day age groups, and these were less than in 10 day and 20-30 day rats. 5. Peak nerve response during hypoxia increased with age from 4.5 +/- 0.6 Hz in the 1 day to 10.5 +/- 1.6 Hz in the 6 day and to 15.5 +/- 2.2 Hz in the 20-30 day rats. 6. We conclude that (1) resting free tissue catecholamine levels increase with age in the newborn period, (2) hypoxia causes enhanced catecholamine release, and (3) the magnitude of the release increases in the postnatal period as does the nerve activity.

Astemizole-induced cardiac conduction disturbances in a child.

The newly available antihistamine astemizole (Hismanal) has been previously associated with hemodynamically significant cardiac tachydysrhythmias. We describe a 3-year-old girl who developed multiple different cardiac dysrhythmias after an astemizole overdose. No hemodynamic compromise occurred, and the electrocardiogram returned to normal without use of antiarrhythmic agents within 7 hours.

Mitral valve prolapse requiring surgery. Clinical and pathologic study.

The clinical, hemodynamic, surgical, and pathologic findings in 30 patients who required mitral valvular surgery and who had a preoperative diagnosis of mitral valve prolapse were reviewed. The mean age of the patients was 59.5 years; 28 patients were over 45 years of age and 10 were over 60 years. Surprisingly, 20 were males. A long history of systolic murmur was common, whereas symptoms of heart failure were of abrupt onset. At the time of surgery, a local holosystolic murmur typical of mitral regurgitation was present, although a mid- to late systolic click was not heard in any of the patients. Electrocardiographic abnormalities were present in all patients, with 13 patients demonstrating atrial fibrillation. Only four patients had a normal heart size radiographically. Echocardiography confirmed the radiographic findings, in that 27 patients demonstrated left atrial and ventricular enlargement. All 29 patients undergoing cardiac catheterization and angiography demonstrated a prolapsing mitral valve with severe regurgitation. Surgical and pathologic examination revealed findings characteristic of a myxomatous valve in all patients, with 19 also demonstrating ruptured chordae tendineae. This study demonstrates that heart failure requiring valvular surgery occurs in a subset of patients with mitral valve prolapse. In this subset, males predominate and most are over 50 years of age. These patients may be asymptomatic for many years, demonstrating mild to moderate mitral valvular regurgitation, before heart failure develops.

Stress echocardiography with transesophageal atrial pacing: preliminary report of a new method for detection of ischemic wall motion abnormalities.

We performed two-dimensional echocardiography in 19 patients with significant coronary artery disease and in six normal volunteers at rest and during transesophageal atrial pacing. Technically adequate resting echocardiograms were obtained in 18 of the 19 patients and in all six normal volunteers. In two subjects, atrial capture was not possible, and in one subject, discomfort from the pacing at the beginning of the study precluded its completion. In all subjects (n = 21) who completed the protocol satisfactory two-dimensional echocardiograms were obtained during pacing. Wall motion was normal at rest and during atrial pacing in five normal volunteers. New transient wall motion abnormalities developed in 13 of the 16 patients during pacing. Twelve of the 13 patients had significant coronary lesions in the coronary arteries supplying the abnormal wall segment. Only three of the patients developed significant ST segment depression during pacing. We conclude that stress echocardiography with transesophageal atrial pacing is safe and practical and can be used in patients who cannot perform dynamic exercise, this technique can detect ischemic segmental wall motion abnormalities corresponding to the distribution of coronary arterial obstruction, and the technique provides high-quality echocardiographic images during stress and thus may expand the usefulness of resting two-dimensional echocardiography in patients who have ischemic heart disease.