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Data from exercise tests, echocardiograms, and lung perfusion scans were analyzed to determine whether the excessive minute ventilation (VE) often encountered among patients with tetralogy of Fallot is due to ventilation-perfusion mismatch secondary to branch pulmonary artery stenoses. Patients with branch PA stenoses had lower peak oxygen consumptions and higher VE during exercise than did patients without stenoses, and a strong correlation existed between the degree of pulmonary blood flow maldistribution on lung perfusion scan and the amount of excessive VE during exercise. [ABSTRACT FROM AUTHOR]

Background: Experience of balloon dilation of peripheral pulmonary stenosis (PPS) in Williams syndrome (WS) is limited., Methods and Results: Catheterizations in all patients with WS undergoing therapy for PPS from 1984 to 1999 were reviewed. Criteria for successful dilation included an increase >50% in predilation diameter and a decrease >20% in ratio of right ventricular (RV) to aortic (Ao) systolic pressure. Median age and weight were 1.5 years and 9.5 kg. There were 134 dilations during 39 procedures in 25 patients. The success rate for initial dilations was 51%. In multivariate analysis, successful dilation was more likely (1) in distal than in central pulmonary arteries (P=0.02), (2) if the balloon waist resolved with inflation (P=0.001), and (3) with larger balloon/stenosis ratio (P<0.001). RV pressure was unchanged after dilation (96+/-30 versus 97+/-31 mm Hg), primarily because of failure to enlarge central pulmonary arteries. The Ao pressure increased (102+/-14 versus 109+/-19 mm Hg, P=0.03), and the RV/Ao pressure ratio decreased (0.97+/-0.34 versus 0.91+/-0.30, P=0.05). Aneurysms developed after 24 dilations (18%) and were not related to balloon/stenosis ratio. Balloon rupture in 12 dilations produced an aneurysm in all 7 cases when rupture was in a hypoplastic segment. Three patients died, none from pulmonary artery trauma, and all before 1994., Conclusions: Mortality occurred early in our experience. Despite successful dilation of distal pulmonary arteries, there was modest initial hemodynamic improvement, mainly because of persistent central pulmonary artery obstruction. A serial approach of distal dilations followed by surgical repair of proximal obstruction may be a rational and successful therapy.

A persistent left superior vena cava connection to an unroofed coronary sinus is a rare cardiac anomaly that is associated with a variable degree of cyanosis. We report an infant with this condition and the unusual feature of cyanosis dependent on head position. When the patient's head was rotated to the left, he developed severe stenosis of the left internal jugular vein, enlarged cervical collateral veins that connected to the right superior vena cava and had an oxygen saturation 95%. When the patient's head was rotated to the right, the left internal jugular vein was widely patent and systemic oxygen saturation decreased to 87%. There was no right ventricular volume overload. Temporary occlusion of the left superior vena cava documented tolerable proximal venous pressure. Cyanosis was relieved by transcatheter closure of the left superior vena cava with a Gianturco-Grifka vascular occlusion device. Cathet. Cardiovasc. Intervent. 48:369-373, 1999., (Copyright 1999 Wiley-Liss, Inc.)

We report a 52-year-old adult with Ebstein's anomaly associated with severe valvar pulmonary stenosis, secundum atrial septal defect, polycythemia, hypoxemia, and severe exertional limitations. Balloon pulmonary valvuloplasty relieved the valvar obstruction, reduced the degree of tricuspid regurgitation and polycythemia, and improved systemic oxygenation and exercise abilities. Use of this technique in patients with this combination of lesions can postpone the need for surgical intervention.

Catheter-induced ventricular ectopy can limit assessment of contractility or anatomy. We compared the incidence of ventricular ectopy in infants and children undergoing left ventriculography using a 4F Halo catheter or a 4F pigtail catheter. For each group, 17 patients had 19 ventriculograms. Iopamidol 76% was used for each study. There was no statistical difference between the Halo and pigtail groups (mean+/-SEM) for age (16.2+/-3.8 vs. 12.9+/-1.8 mo), weight(8.1+/-1.0 vs. 8.0+/-0.7 kg), gender, left ventricular end diastolic pressure (9.6+/-1.1 vs. 9.8+/-1.3 mm Hg), catheter location in the ventricle, or volume of contrast (1.31+/-0.06 vs. 1.35+/-0.06 cc/kg). The Halo group had a more rapid injection rate (1.42+/-0.15 vs. 0.99+/-0.10 cc/kg/sec, P< 0.02). The Halo group had a lower overall incidence of ventricular ectopy (3 vs. 13 studies, P < 0.001), ventricular ectopy >1 beat (1 vs. 10 studies, P < 0.002), and ventricular couplets or tachycardia (1 vs. 9 studies, P < 0.008). The 4F Halo catheter is associated with less ventricular ectopy than a 4F pigtail catheter and should be considered for use during pediatric catheterization.

Following surgery for tetralogy of Fallot (TOF), children may develop late onset ventricular arrhythmias. Many patients have both depolarization and repolarization abnormalities, including right bundle branch block (RBBB) and QT prolongation. The goal of this study was to improve prospective risk-assessment screening for late onset sudden death. Resting ECG markers including QRS duration, QTc, JTc, and interlead QT and JT dispersion were statistically analyzed to identify those patients at risk for ventricular arrhythmias and sudden cardiac death. To determine predictive markers for future development of arrhythmia, we examined 101 resting ECGs in patients (age 12 +/- 6 years) with postoperative TOF and RBBB, 14 of whom developed late ventricular tachycardia (VT) or sudden death. These ECGs were also compared with an additional control group of 1000 age- and gender-matched normal ECGs. The mean QRS (+/- SD) in the VT group was 0.18 +/- 0.02 seconds versus 0.14 +/- 0.02 seconds in the non-VT group (P < 0.01). QTc and JTc in the VT group was 0.53 +/- 0.05 seconds and 0.33 +/- 0.03 seconds compared with 0.50 +/- 0.03 seconds and 0.32 +/- 0.03 seconds in the non-VT group (P = NS). There was no increase in QT dispersion among TOF patients with VT or sudden death compared with control patients or TOF patients without VT, although JT dispersion was more common in the TOF groups. A prolonged QRS duration in postoperative TOF with RBBB is more predictive than QTc, JTc, or dispersion indexes for identifying vulnerability to ventricular arrhythmias in this population, while retaining high specificity. The combination of both QRS prolongation and increased JT dispersion had very good positive and negative predictive values. These results suggest that arrhythmogenesis in children following TOF surgery might involve depolarization in addition to repolarization abnormalities. Prospective identification of high-risk children may be accomplished using these ECG criteria.

Objectives: To determine whether survivors of surgery for coarctation of the aorta (CoA) have an excessive reliance on anaerobic metabolism during exercise., Background: Patients with peripheral vascular disease cannot increase blood flow to their muscles normally during exercise. Consequently they acquire an early, excessive reliance on anaerobic metabolism and have depression of the ventilatory anaerobic threshold (VAT) and of the slope of the oxygen consumption-work rate relationship (delta VO2/delta WR). We speculated that the capacity to augment blood flow to the lower extremities during exercise may be impaired after CoA surgery and would result in similar metabolic disturbances., Study Design: Progressive exercise tests were performed on 15 patients (ages 19 +/- 7 years; range, 10 to 32) after successful repair of CoA (residual resting gradient, 7.7 +/- 7.1 mm Hg; range, 0 to 18), 15 age- and sex-matched healthy control subjects, and 10 patients (ages 13 +/- 3 years; range, 10 to 20) who had undergone ligation of a patent ductus arteriosus., Results: The CoA patients' VAT averaged 14.8 +/- 3.8 ml O2/kg per minute versus 19.3 +/- 3.1 ml O2/kg per minute for the control subjects (p < 0.01), and their delta VO2/delta WR averaged 8.2 +/- 1.8 ml/watt compared with 10.1 +/- 1.4 ml/watt for control subjects (p < 0.01). Furthermore, 10 of 15 CoA patients had a VAT of less than 40% of predicted maximal oxygen consumption, and 9 of 16 had a delta VO2/delta WR of less than 8.7 ml O2/watt (generally accepted abnormal values). Patients with patent ductus arteriosus resembled the healthy control subjects with regard to anaerobic metabolism during exercise., Conclusions: Patients who have had CoA repairs commonly manifest an excessive reliance on anaerobic metabolism during exercise. This phenomenon may result from persistent blood flow abnormalities across the aortic arch during exercise, which may be present even after apparently successful surgery.

Lung perfusion scans reveal that multiple-coil closure of the ductus does not interfere with pulmonary blood flow. However, caution is necessary when placing multiple coils in small infants.

Ninety-seven of 100 patients had a successful attempt at coil closure of the patent ductus arteriosus. For all 46 patients in whom a single coil and in 47 patients in whom multiple coils were placed, there was immediate complete closure that persisted at a median follow-up period of 1.9 years.

Balloon atrial septostomy remains an important interventional procedure in the pediatric age group. The incidence of potential complications using the conventional balloon ranges from 0-11%. The purpose of this study was to evaluate a new low-profile end-hole septostomy balloon catheter with dual lumen, inserted via a 5F or 6F sheath. Seventeen neonates and infants with various forms of congenital heart disease requiring palliation underwent septostomy using the new catheter at a median age of 19 days (with a range of 1-593 days), and a median weight of 3.4 kg (a range of 2.5-8.4 kg). The aortic saturation increased from 72 +/- 20% to 87 +/- 7%, p < .001; and the gradient across the atrial septum decreased (a-wave gradient from 11.2 +/- 10.3 to 2.1 +/- 3.6 mm Hg; v-wave from 10.4 +/- 7.7 to 1.2 +/- 1.2 mm Hg; and mean gradient from 8.5 +/- 6.9 to 0.9 +/- 1.3 mm Hg, p < .002). The diameter of the defect increased from 2.7 +/- 1.7 mm to 8 +/- 2.3 mm, p < .001. There were no complications. We conclude that this new low-profile septostomy catheter is safe and effective in creating a large defect size between the atria. Because of the smaller inflation size of the balloon and smaller introducer sheath compared with the conventional catheter, this new septostomy catheter should be especially useful in small neonates.

We describe two brothers with congenital lymphedema of lower limbs, atrial septal defect (ASD), and similar facial appearance. A sister had severe hydrops fetalis, ASD, omphalocele, and other anomalies. This combination of congenital lymphedema and ASD differs from other reported cases of congenital lymphedema and most likely constitutes a previously unrecognized autosomal recessive syndrome.

Experience with transcatheter closure (TCC) of patent ductus arteriosus (PDA) in small infants is limited. Our goals were to evaluate the immediate and short-term results of TCC of PDA in small infants (< or = 8 kg) as attempted with single or multiple Gianturco coils and to compare results for PDA < or = 2.5 mm versus PDA > 2.5 mm. Twenty-four infants underwent an attempt at TCC of PDA at a median age of 0.7 years (range 2 weeks to 1.5 years) and median weight of 6.5 kg (range 2.3 to 8 kg). Coils were placed by the transvenous route in 14 patients and by the transarterial route in 10 patients. The median PDA diameter was 2.7 mm (range 0.4 to 5.2 mm). Ten patients had PDA diameters < 2.5 mm and all had complete closure, 9 with a single coil and 1 with two coils. Fourteen patients had PDA diameters > or = 2.5 mm; closure was complete in 10 patients, 9 of whom required multiple coils. There was a trend toward improved results with multiple coils delivered transvenously. There was immediate complete closure of the PDA with a diameter as large as 5.2 mm that persisted at a median follow-up period of 1.2 year. Closure was unsuccessful in 4 patients, each of whom required multiple coils. The median fluoroscopy time was 19 minutes. Complications included transient loss of femoral pulse in 2 infants, mild left pulmonary artery obstruction in 2, and nonretrievable coil migration to the right lung in one. We conclude that TCC is effective therapy for small infants with a PDA of diameter < or = 5.2 mm by the single-or multiple-coil technique on an outpatient basis and that TCC can be performed in neonates as small as 2.3 kg.

We report two infants each with coarctation of the aorta and small patent ductus arteriosus who had balloon angioplasty therapy for aortic obstruction at 3-6 months of age followed by anterograde placement of a single Gianturco coil to close the ductus at a separate catheterization. One infant developed recoarctation that resolved with repeat angioplasty prior to closure of the ductus. Follow-up evaluations have demonstrated a trivial aortic gradient, no aortic aneurysm, and no residual shunt.

Our objective was to assess the immediate and short-term results of stent implantation to relieve pulmonary artery stenosis (PAS). Thirty-seven patients underwent an attempt at stent implantation at a median age of 7.0 years (range, 0.8-31.4 years) and a median weight of 20.5 kg (range, 7.4-85 kg). Twenty-two patients had previous tetralogy of Fallot repair. A total of 55 stents were implanted successfully in 36 patients. The peak systolic gradient across the stenotic segment decreased from a mean of 43 +/- 20.4 mmHg prestent to 13 +/- 13.9 mmHg (P < 0.001) poststent. The diameter of the narrowest segment increased from a mean of 4.8 +/- 1.6 mm to 10.5 +/- 2.6 mm (P < 0.001). The right ventricular-to-aortic mean systolic pressure ratio decreased from 0.74 +/- 0.2 to 0.52 +/- 0.19 (P < 0.001). Complications included balloon rupture prior to full stent expansion in 4 patients (in 2 patients the stent was positioned in the superior vena cava, and in 2 in the inferior vena cava), distal migration of a stent which was successfully retrieved at surgery 1 mo later in 1 patient, and tethering of the stent to the balloon requiring surgical removal in 1 patient. One patient died several hours after stent placement. Sixteen patients underwent repeat catheterization at a mean follow-up interval of 0.9 +/- 0.5 years (range, 0.2-2.0 years). The mean gradient across the stent for these 16 patients was 26.7 +/- 19.8 mmHg, and there was no change in the mean diameter (9.4 +/- 3.2 mm). Two patients developed stenosis related to neointimal proliferation at the stent site which was redilated successfully. In conclusion, stent implantation is generally safe and effective in relieving PAS.

Partial anomalous pulmonary venous drainage with intact atrial septum is a rare congenital anomaly. We report a case of a 63-year-old woman who recently had dyspnea on minimal exertion and was found to have pulmonary hypertension, right atrial enlargement, and right ventricular enlargement by two-dimensional transthoracic echocardiography. Transesophageal echocardiography demonstrated anomalous venous drainage of the right lung into the superior vena cava with an intact interatrial septum. This diagnosis was confirmed by angiography and the patient underwent successful repair. This case illustrates the importance of locating all four pulmonary veins in patients with pulmonary hypertension or suspected intracardiac shunt in addition to scanning the atrial septum.

Transcatheter closure of a patent ductus arteriosus (PDA) using the Rashkind occluder or the buttoned device is accompanied with a 7-38% incidence of residual shunt. Closure of the residual shunt with a second device is expensive, associated with possible morbidity, can be technically challenging, and occasionally does not completely eliminate the shunt. Our objective was to assess the immediate and short-term results of transcatheter closure of residual PDA after the Rashkind device using single or multiple Gianturco coils. Five patients (one male/four female) underwent transcatheter closure of residual PDA at a median age of 8.4 yr (range 2-10.1 yr) and median weight of 23 kg (range 11.8-32 kg). A 4F catheter was used for delivery of the coils in all patients. Three patients underwent multiple coil and two single coil closure with complete elimination of the shunt. There was complete elimination of the shunt as documented by repeat angiography immediately after the coil closure. The median fluoroscopy time was 24 min (range, 22-55 min). All patients were discharged home on the same day. There were no complications Follow-up evaluation was performed with color flow mapping of the main pulmonary artery within 4 hr after closure and 6 weeks later with echocardiography and chest radiography. We conclude that transcatheter closure is an effective therapy for patients with residual PDA after the Rashkind device using the single or multiple coil technique. This technique can be performed on an out-patient basis without the need for general anesthesia and at a lower expense than a repeat occluder device or surgery.

Objective: To evaluate the safety and efficacy of a new low profile balloon septostomy catheter in neonatal animals as well as in one newborn infant., Background: Balloon atrial septostomy remains one of the most commonly performed palliative procedures in pediatric cardiology. The currently available septostomy catheter requires a large introducer sheath (6 or 7F), does not have an end hole for confirmation of position or pressure measurement and is limited in patients with a small left atrium due to its large balloon inflated diameter., Methods: Four neonatal piglets (average weight 3.9 kg) underwent percutaneous balloon atrial septostomy using the new balloon catheter inflated to 1 cc via a 5F sheath in the femoral vein. Two other piglets (average weight 4.9 kg) underwent septostomy with the conventional catheter inflated to 3.5 cc via a 6 or 7F sheath in the femoral vein. All animals underwent transthoracic echocardiography pre and post septostomy. All animals were sacrificed after the procedure and the size of the atrial defect created was measured. One neonate with Taussig-Bing anomaly underwent septostomy with the new balloon catheter., Results: The left atrium was entered in all piglets. It was easier to enter the left atrium with an end hole catheter which was exchanged over a wire with the septostomy catheter. Septostomy was performed with the new or conventional catheters without complications. Echocardiography demonstrated a very small patent foramen ovale prior to the procedure and a large atrial defect after septostomy. The average size of the defect created by the new catheter was 11.3 x 10 mm in diameter and 11 x 10 mm using the conventional catheter. A 10 x 10 mm atrial communication was created in the neonate., Conclusions: This study demonstrates the safety and efficacy of this new catheter. This catheter will be of potential importance in patients with a small left atrium and in small neonates with congenital heart disease requiring septostomy.

Background: Severe pulmonary regurgitation (PR) and associated right ventricular (RV) dilatation are late complications of surgical repair of tetralogy of Fallot (TOF). For the past several years, we have restored pulmonary valve competence with the exclusive use of cryopreserved allografts., Methods and Results: Sixteen patients with symptoms of diminished exercise tolerance and echocardiographic evidence of progressive PR with severe RV dilatation underwent placement of allografts in the RV outflow tract at a median age of 12 years (10 years after TOF repair). Abnormal exercise tolerance tests were documented in 10 patients. Additional surgical procedures included pulmonary artery augmentation (n = 6), closure of residual left to right shunts (n = 3), and subendocardial resection for monomorphic ventricular tachycardia (n = 1). Six patients had either preoperative or postoperative balloon dilations of pulmonary artery stenoses. All patients had symptomatic improvement after allograft insertion. At a mean follow-up of 26.4 +/- 3.4 months, the severity of PR improved in all but one patient. In 12 patients (group 1), conduit regurgitation was either trace (n = 11) or mild (n = 1). Four patients (group 2) had moderate conduit regurgitation. In a retrospective analysis, pulmonary artery diameters and cross-sectional areas were significantly smaller in the group 2 patients compared with the group 1 patients. With the exception of one patient, RV end-diastolic diameter (RVEDD/BSA) fell after allograft insertion in each patient (P < .01). The reduction in RVEDD/BSA was significantly greater in group 1 than in group 2 (31.8 +/- 3.4% versus 21.4 +/- 11.0%, P < .05)., Conclusions: Thus, restoration of the pulmonary valve with cryopreserved allografts improved exercise tolerance and diminished RV volume overload in patients with severe PR after previous repair of TOF. Optimal results were achieved in patients who did not have significant residual pulmonary artery distortion.

A 1-year-old female child was diagnosed to have scimitar syndrome associated with partial anomalous pulmonary venous connection of the right lung at the superior vena cava-right atrial junction, right atrium, and inferior vena cava. To our knowledge, this pattern of pulmonary venous connection has not been previously described in this syndrome.

We performed examinations and echocardiographic studies in 35 patients with Down syndrome (aged 20 +/- 4.2 years) with no known intracardiac disease. Sixteen patients (46%) had mitral valve prolapse; two of these also had tricuspid valve prolapse. Two had aortic regurgitation. Valve regurgitation was present in 4 (17%) of 23 patients more than 18 years of age but in none of the 12 patients 18 years of age or younger. We recommend screening of adolescent and young adult patients with Down syndrome for the development of valve dysfunction, especially before dental or surgical procedures.

A monozygotic twin boy with supravalvar aortic stenosis had reduction in the degree of obstruction with body growth. His twin brother had normal cardiac anatomy. To our knowledge, this is the first report of improvement without intervention in a patient with supravalvar aortic stenosis and of discordance of supravalvar aortic stenosis in monozygotic twins.

Fifty-six patients undergoing a modified Fontan procedure from 1977 to 1985 had lung tissue available from the perioperative period (n = 51) or recent palliative procedure (n = 5) (37 biopsy, 12 autopsy, 7 biopsy and autopsy). Twenty-six patients had tricuspid atresia, and 30 had other causes of functional univentricular heart. Pulmonary arterial structure was classified by both the Heath-Edwards and morphometric scales. Biopsy and autopsy grades were identical except for a minor difference in Heath-Edwards scale in one case. Elevated preoperative mean pulmonary artery pressure (greater than 15 mm Hg) was associated with medial hypertrophy (p = 0.04), although six patients with normal pulmonary artery pressure had medial hypertrophy and six patients with mean pulmonary artery pressure greater than 15 mm Hg did not have medial hypertrophy. Medial hypertrophy was a possible risk factor in patients with univentricular heart: Patients with medial hypertrophy had a ninefold greater risk of death (p = 0.08). Controlling for confounding variables did not alter this result (0.06 less than or equal to p less than or equal to 0.10). Medial hypertrophy was not a risk factor for death in patients with tricuspid atresia: Four had this feature and each survived. Four patients with tricuspid atresia died and none had medial hypertrophy. A mean transpulmonary pressure gradient was measured on the first postoperative day in 45 patients. In patients with medial hypertrophy there was a trend toward a higher gradient (p = 0.13). All patients with medial hypertrophy who had this measurement (n = 9) had a transpulmonary pressure gradient of 7 mm Hg or greater, whereas this was true in only 18 of 36 without medial hypertrophy (p = 0.007). On the basis of an evaluation of medial hypertrophy, we conclude that biopsy does not aid in selection of patients with tricuspid atresia for a Fontan procedure; its role in patients with univentricular heart is uncertain.

Some infants with congenital diaphragmatic hernia who die after surgical correction have a transient postoperative period during which systemic oxygenation is adequate (honeymoon period), whereas others have persistent hypoxemia. Using morphometric techniques, we analyzed lung structure, especially the arterial bed, in seven infants who died within 1 week of surgical repair. Three infants comprised the honeymoon group, the PaO2 transiently being greater than 150 mm Hg in the descending aorta (FiO2 1.0); four infants comprised the no-honeymoon group and never had PaO2 greater than 85 mm Hg. All lungs were hypoplastic for age; with one exception, infants in the no-honeymoon group had smaller lungs. Arterial structure in the no-honeymoon group contributed to a greater reduction in pulmonary arterial cross-sectional area. Each infant in the no-honeymoon group had muscularization of intra-acinar arteries and failure of perinatal increase in compliance of small preacinar arteries, features not seen in the honeymoon group or in the normal newborn infant. In addition, compared with the honeymoon group, luminal area of preacinar and intra-acinar arteries in the no-honeymoon group was decreased by reduced external diameter or increased medial thickness. Clinical deterioration in the honeymoon group is based on a vasoconstrictive response of the hypoplastic vascular bed. Persistent hypoxemia in the no-honeymoon group is based on both severity of pulmonary hypoplasia and structural remodeling of the pulmonary arteries.

Discussed in this article are the three main anatomic types of persistent pulmonary hypertension of the newborn; (1) maladaptation of the pulmonary vascular bed; (2) excessive muscularization of the pulmonary vascular bed; and (3) underdevelopment of the pulmonary vascular bed.

A male infant is described who died at 13 months of age with stenosis of all extrapulmonary veins except the left upper vein. The pulmonary artery wedge pressure was normal, the first time this is reported in this condition. At autopsy, there were structural changes of the pulmonary arteries and veins in all lobes with or without pulmonary vein stenosis. Arterial changes-muscle extension, medial hypertrophy and decreased arterial size--analyzed quantitatively were found to be similar in all lobes. Venous medial hypertrophy was more marked in obstructed lobes. These anatomic changes are presumably due to fixed venous obstruction in the pulmonary lobes drained by stenotic veins and to high flow in the left upper lobe.

An infant girl is described who had cor triatriatum and partial anomalous pulmonary venous connection of the left pulmonary veins to the coronary sinus, the first report of this combination of lesions. The infant also had a Dandy-Walker malformation and multiple facial and intrathoracic hemangiomas. The cardiac diagnosis was made by two-dimensional echocardiography. Cardiac catheterization and angiography confirmed the findings and also demonstrated a persistent left superior vena cava draining to the coronary sinus. The infant underwent successful surgical repair. Partial anomalous pulmonary venous connection and left superior vena cava not infrequently are associated with cor triatriatum. Although two-dimensional echocardiography is sensitive for the detection of cor triatriatum, preoperative cardiac catheterization is necessary to identify unequivocally systemic and pulmonary venous connections.

Idiopathic persistent pulmonary hypertension of the newborn infant (PPHN) is characterized by intrauterine structural remodeling of the pulmonary arterial bed, consisting of precocious development of muscle in intraacinar arteries, proliferation of adventitial connective tissue, and sometimes medial hypertrophy of preacinar arteries. To evaluate whether gestational hypoxemia causes these changes, we studied pulmonary arterial structure in two groups of newborn rats: one control, the other exposed to hypoxemia produced by maternal hypoxia during the second half of gestation. Morphometric analysis of the pulmonary arterial bed was performed after barium injection into the pulmonary arteries and formol saline expansion of the air spaces. Birth weight was similar in each group. Hematocrit was elevated in the hypoxemia group (51% +/- 1.0% vs 46% +/- 0.8%, P less than 0.005). The structure of preacinar and intraacinar arteries was similar and normal in both groups. Chronic fetal hypoxemia in the rat does not produce the pulmonary arterial structural changes identified in fatal cases of PPHN in human infants.

In primary pulmonary hypertension of recent clinical onset, pulmonary endothelial cells show injury. To characterize this phenomenon, we measured plasma von Willebrand factor (vWF) by immunologic and ristocetin cofactor assays in 6 patients with primary pulmonary hypertension, 17 patients with secondary pulmonary artery hypertension associated with congenital heart disease or cystic fibrosis, and 13 patients with congenital heart disease and normal pulmonary artery pressure. In selected cases, we also determined the vWF multimer pattern. In all 6 cases of primary pulmonary hypertension, the ristocetin cofactor activity was increased relative to the vWF antigen (vWF:Ag) concentration (a ratio of 2.55 +/- 0.36; normal range, 0.8 to 1.4); 4 of the 6 also had a similar and abnormal vWF multimer pattern--an increased proportion of the fastest moving bands. In the other 2, the multimer pattern was normal. Of the other 30 patients, a mild increase in ristocetin cofactor/vWF:Ag was seen in only 2 with secondary pulmonary hypertension and 1 with normal pulmonary artery pressure: these also had an abnormal vWF multimer pattern that was different from that observed in patients with primary pulmonary hypertension. The vWF abnormalities we describe in primary pulmonary hypertension offer a marker of the disease and could be helpful in understanding its pathogenesis.

Six clinically stable patients with cystic fibrosis (24 to 31 yr of age) and severe pulmonary impairment, right ventricular hypertrophy, and previous right-sided heart failure underwent cardiac catheterization to assess the hemodynamic effects of oxygen (fraction of inspired O2, 0.31, 0.50), phentolamine (5 mg intravenously), hydralazine (0.33 mg/kg intravenously), and nifedipine (20 mg sublingually). Measurements during dynamic exercise were also obtained before and after hydralazine therapy. Studies after 5 to 8 wk of continuous, orally administered hydralazine therapy were performed in 3 patients. The resting mean pulmonary artery pressure was 31 +/- 4 mmHg. At rest, only oxygen was a selective pulmonary vasodilator, decreasing pulmonary artery pressure and pulmonary vascular resistance in all patients. Systemic arterial pressure and resistance were not significantly changed. Phentolamine, hydralazine, and nifedipine did not alter pulmonary artery pressure or selectively affect the pulmonary vascular bed, reducing both calculated pulmonary and systemic vascular resistance, the latter to a similar or greater degree. Hydralazine and nifedipine significantly increased cardiac index and decreased systemic arterial pressure. Nifedipine mildly decreased systemic oxygenation. During exercise, the mean pulmonary artery pressure increased to 51 +/- 15 mmHg. Hydralazine increased systemic and mixed venous oxygenation both at rest and during exercise but did not alter the elevation in pulmonary artery pressure observed during exercise. After orally administered hydralazine therapy, oxygen delivery and cardiac index remained increased in 2 patients. These data support the use of oxygen but not of the other agents in patients with cystic fibrosis and chronic cor pulmonale unless the ability of hydralazine to increase oxygen delivery is determined to improve prognosis.