Case report: pulmonary vein stenosis following RF ablation of paroxysmal atrial fibrillation: successful treatment with balloon dilation.

Paroxysmal atrial fibrillation and atrial tachycardia may originate from a focal source in one or multiple pulmonary veins. A focal origin facilitates a potential cure amendable to radiofrequency ablation. Herein we report the case of a 16 year old adolescent male with a tachycardia induced cardiomyopathy who presented with very frequent paroxysmal episodes of atrial fibrillation, atrial flutter and atrial tachycardia. The origin of the arrhythmia was mapped to the secondary branches of the left lower pulmonary vein using an octapolar micro-mapping catheter. Immediately following application of three radiofrequency lesions, angiography of the left lower pulmonary vein revealed a region of focal stenosis at the site of energy application, with delayed pulmonary venous emptying. Attempts to relieve any element of spasm using direct administration of nitroglycerin were unsuccessful. Three months later repeat catheterization revealed an unchanged region of tight anatomical stenosis. Balloon dilation of two stenotic areas resulted in dramatic relief of the obstruction and improved venous drainage. Recatheterization 6 months later revealed mild restenosis that was successfully redilated. Intracardiac ultrasound demonstrated focal constriction. Care should be exercised in attempting RF ablation in distal arborization sites of the pulmonary veins in children, because of the small caliber compared to adult subjects. Radiofrequency induced focal areas of stenosis may be amenable to balloon catheter dilation.

Use of inhaled nitric oxide and acetylcholine in the evaluation of pulmonary hypertension and endothelial function after cardiopulmonary bypass.

BACKGROUND: Increased pulmonary vascular resistance is common in congenital heart disease and is exacerbated by cardiopulmonary bypass (CPB). We investigated whether CPB is responsible for pulmonary endothelial dysfunction and contributes to postoperative pulmonary hypertension. METHODS AND RESULTS: We infused the endothelium-dependent vasodilator acetylcholine (ACH) into the pulmonary circulation of pulmonary hypertensive children with congenital heart disease either before (n = 12) or after (n = 22) surgical repair on CPB. The dose response to ACH (10(-9) to 10(-6) M) was recorded for all hemodynamic variables. Nine additional postoperative patients were studied with ACH followed by inhalation of 80 ppm nitric oxide, an endothelium-independent smooth muscle relaxant. Plasma levels of cyclic GMP (cGMP) were measured before and after ACH and nitric oxide administration. Pulmonary vasodilation with 10(-6) M ACH was seen in all preoperative patients but was markedly attenuated in postoperative patients. Baseline pulmonary vascular resistance (5.6 +/- 1.0 U x m2) fell 46 +/- 5% in preoperative patients but declined only 11 +/- 4% from baseline (5.8 +/- 0.9 U x m2) in postoperative patients (P < .002). However, inhalation of 80 ppm nitric oxide after ACH infusion in postoperative patients lowered pulmonary vascular resistance by 33 +/- 4% (P < .0002 compared with postoperative ACH response) with minimal effects on the systemic circulation. This finding suggests that the capacity for smooth muscle relaxation and pulmonary vasodilation was present in postoperative patients but could not be induced by ACH. Plasma levels of cGMP in postoperative patients were unchanged after acetylcholine infusion but rose more than threefold during pulmonary vasodilation with nitric oxide (P < .0001). This finding is consistent with the purported role of cGMP as the second messenger effecting smooth muscle relaxation in this process. CONCLUSIONS: CPB may be responsible for postoperative dysfunction of the pulmonary endothelial cell and may contribute to postoperative pulmonary hypertension in children. Inhaled nitric oxide is a potent pulmonary vasodilator after CPB with minimal systemic circulatory effects. It may have important diagnostic and therapeutic applications in patients with congenital heart disease.

Diagnosis and management of right ventricle-dependent coronary circulation in pulmonary atresia with intact ventricular septum.

BACKGROUND: Coronary artery anomalies including 1) right ventricle (RV)-to-coronary artery fistulas, 2) coronary artery stenoses, and 3) coronary occlusions occur in patients with pulmonary atresia with intact ventricular septum (PA-IVS). In some, a large part of the coronary blood supply may depend on the RV. This RV-dependent coronary circulation may determine survival after right ventricular decompression (RVD): RVD may cause RV "steal" in the presence of fistulas alone and ischemia, coronary isolation, or myocardial infarction in the presence of coronary stenoses. METHODS AND RESULTS: Eighty-two patients with PA-IVS who presented between January 1979 and January 1990 were reviewed; 26 (32%) had RV-to-coronary artery fistulas. Of these 26, 23 had adequate preoperative coronary angiograms for analysis. RVD was achieved in 16. Seven of 16 had fistulas only; each survived RVD. Six of 16 had stenosis of a single coronary artery [left anterior descending coronary artery (LAD), four; right coronary artery (RCA), two]; four of six survived RVD. Three of 16 had stenoses and/or occlusion of both the RCA and LAD; all three died shortly after RVD of acute left ventricular dysfunction. CONCLUSIONS: 1) Potential RV steal alone does not preclude successful RVD. 2) Fistulas with stenoses to a single coronary artery may not preclude successful RVD. 3) RVD appears to be contraindicated in the presence of stenoses and/or occlusion involving both the right and left coronary systems. Nonsurvival after RVD seems to depend on the amount of the left ventricular myocardium at risk, i.e., that which is distal to coronary artery stenoses, especially when involvement of both coronary arteries limits effective collateralization. Precise definition of coronary arterial anatomy is mandatory in neonates with PA-IVS.

Course in the intensive care unit after 'preparatory' pulmonary artery banding and aortopulmonary shunt placement for transposition of the great arteries with low left ventricular pressure.

BACKGROUND: In patients with transposition of the great arteries with low left ventricular pressure, pulmonary artery banding with aortopulmonary shunt placement has been advocated to "prepare" the left ventricle for systemic work before an arterial switch operation. METHODS AND RESULTS: In 28 patients, this preparatory procedure was performed with one death. A successful arterial switch operation was performed at a median of 7 days later in 24 of 27 survivors; one child had a Senning performed, and two others died. During this interval period, the left ventricular-to-right ventricular pressure ratio increased from 48 +/- 8% to 98 +/- 19%, and left ventricular mass (indexed for body surface area) increased from 46 +/- 17 to 72 +/- 23 g/m2. After the preparatory procedure, the initial postoperative period was frequently characterized by a low-output syndrome of variable length and severity. Prolonged mechanical ventilation, extended inotropic support, and/or a significant metabolic acidosis was present in 21 of 28 patients in the immediate postoperative period. CONCLUSIONS: The low-output syndrome is most likely due to a combination of acute (fixed) right ventricular volume overload from the shunt and acute (transient) left ventricular dysfunction from the pulmonary artery band. This low-output syndrome should be anticipated following the preparatory procedure.

Right ventricular decompression and left ventricular function in pulmonary atresia with intact ventricular septum. The influence of less extensive coronary anomalies.

BACKGROUND: Right ventricular decompression (RVD) may cause myocardial ischemia in patients with pulmonary atresia with intact ventricular septum and associated coronary artery abnormalities. Although we have previously shown that mortality is very high when two or more coronary arteries are obstructed, the effects of lesser degrees of coronary abnormalities are unknown. We therefore evaluated the effect of RVD on left ventricular (LV) function in those with less extensive coronary artery abnormalities. METHODS AND RESULTS: Preoperative cineangiograms demonstrated fistulas with or without one coronary artery stenosis in 12 of 24 patients aged 2 days to 33 months at the time of RVD. Preoperative and postoperative two-dimensional echocardiograms were analyzed for global and regional LV function. One infant with fistulas involving two coronary arteries and stenosis of the right coronary artery died from severe global LV dysfunction after RVD. Despite this, mean LV end-diastolic volume (66 +/- 17 mL/m2) and mean LV ejection fraction (60 +/- 9%) were similar in patients with and without coronary artery abnormalities before and after RVD. Before RVD, regional LV dysfunction was seen in 8 of 132 (6%) regions in those with coronary artery abnormalities and in 3 of 132 (2%) in those without coronary artery abnormalities. After RVD, there were 16 of 132 (12%) abnormal regions in those with coronary artery abnormalities and 1 of 132 (< 1%) in those without coronary artery abnormalities. In regions with normal wall motion before RVD, the presence of coronary artery abnormalities was related to regional LV dysfunction after RVD (P < .001). CONCLUSIONS: Regional LV dysfunction was rare in patients without coronary artery abnormalities. In those with less extensive coronary artery abnormalities not involving obstruction to multiple coronary arteries, regional LV dysfunction was common before and increased after RVD, but severe global LV dysfunction was unusual.

Rapid, two-stage arterial switch for transposition of the great arteries and intact ventricular septum beyond the neonatal period.

Optimal management of dextrotransposition of the great arteries with intact ventricular septum is currently an arterial switch procedure performed in the first 2 weeks of life. However, a subgroup of patients presents for surgery beyond this time for reasons of sickness, size, or late referral. Experience with 11 such patients (mean age at first-stage procedure, 4.5 months) has revealed that the left ventricle can be prepared by a surprisingly short interval period (median, 9 days) between a first-stage preparatory operation (pulmonary artery band with or without a shunt) and a subsequent second-stage arterial switch procedure. Serial two-dimensional echocardiography showed that left ventricular mass increased by a mean of 85% during this short interval. Mean left ventricular-right ventricular-pressure ratio as measured by cardiac catheterization increased from 0.5 +/- 0.08 a median of 7 days before the first stage to 1.04 +/- 0.29 a median of 7 days after the first stage. One patient underwent a Senning procedure because of an intramural left coronary artery. The other 10 patients underwent an arterial switch, with no early deaths. Median hospitalization after the arterial switch was 8 days. There has been one late death at 5 months. No patient has been detected to have abnormal ventricular function, although trivial to mild aortic regurgitation has been commonly observed with color flow mapping. These results have encouraged us to offer a two-stage arterial switch procedure to appropriate infants with an interval period of approximately 1 week. Both stages can be performed at one hospitalization, with important psychosocial, logistic, and financial advantages.

Influence of right heart size on outcome in pulmonary atresia with intact ventricular septum.

BACKGROUND: Neonates with pulmonary atresia and intact ventricular septum (PA-IVS) are frequently born with hypoplastic right heart structures that must grow after right ventricular decompression (RVD) procedures for a complete two-ventricle physiology to be achieved. Previous authors have asserted that neonatal right heart size or morphology will predict right heart growth potential. Since 1983, our bias has favored early RVD regardless of initial right heart size. In 1986, we recognized a subset of patients with coronary artery abnormalities associated with poor outcome after RVD and have defined these patients as having a right ventricular-dependent coronary circulation (RVDCC). METHODS AND RESULTS: To assess the influence of right heart size on outcome independent of the presence of RVDCC, we measured echocardiographic right ventricular (RV) dimensions in 37 neonates with adequate studies presenting between 1983 and 1990. Coronary artery anatomy was adequately assessed by angiography in 36. RV volume and tricuspid valve (TV) diameter were significantly smaller in patients with RVDCC than in those without. However, there was no statistically significant association between RV volume or TV diameter and survival among patients with or without RVDCC: Among 29 patients without RVDCC, 23 of 24 (95.8%) who achieved RVD are alive compared with 1 of 5 (20%) who did not achieve RVD (P = .001). Twenty-one of the 23 survivors have a complete two-ventricle physiology with low right atrial pressure. Among 7 patients with RVDCC, 2 patients who underwent RVD died early of left ventricular failure, whereas 4 of 5 who did not undergo RVD have survived single ventricular palliation. CONCLUSIONS: Small right heart size is associated with RVDCC but is not associated with survival in PA-IVS. Patients without RVDCC have improved survival after RVD regardless of neonatal right heart size.