Pulmonary Outflow Obstruction Research Articles

1002-83 In Utero Pulmonary Outflow Obstruction: Natural History and Predictors of Postnatal Severity

We reviewed prenatal and postnatal echocardiograms of fetuses with pulmonary stenosis (PS, n = 14) and pulmonary atresia (PAtr, n = 5), to elucidate the antenatal natural history of PS and PAtr and identify predictors of severe postnatal disease. Fifteen were serially studied in utero (age at first study 24 ± 4wks). Fetuses with PS were divided into severe and mild groups according to whether they were (9) or were not (4) ductus-dependent at birth, respectively. Measurements of RV short and long-axis, tricuspid valve, main and branch pulmonary artery (PA) and pulmonary valve dimensions were converted to Z-scores based on age-adjusted normal fetal data. At the initial exam, main and branch PA and pulmonary valve Z-scores were larger in fetuses with mild PS than in those with severe PS or PAtr (p ≤ 0.01). On serial followup, however, growth rates of right heart structures did not differ for mild PS versus severe PS and PAtr groups. Ductal flow in utero was antegrade in systole in all with mild PS, but was either bidirectional (5 severe PS) or retrograde only (4 severe PS, all PAtr) in the severe PS and PAtr groups. Initial RV outflow gradients by Doppler did not differ between the mild and severe PS groups with antegrade PA flow (mean 26 ± 12 mmHg). Pulmonary insufficiency was a consistent feature in fetuses with mild PS, but was not present in the severe PS or PAtr groups. By color Doppler, 3/4 with mild PS had mild tricuspid regurgitation, whereas mild or moderate tricuspid regurgitation was found in 9/9 with severe PS and 4/5 with PAtr. When severe PS and PAtr groups were compared, there was no significant difference in initial Z-scores or growth rates of right heart structures between the groups. Tricuspid regurgitation severity and initial RV pressure by the tricuspid regurgitation jet (mean 71 ± 21 mmHg) also did not differ between the severe PS and PAtr groups. On serial followup in 6/8 with severe RV outflow obstruction (1 PAtr, 7 severe PS), the RV pressure increased by 18–47 mmHg. In 3/6 serially studied fetuses with antegrade PA flow (2 severe PS, 1 mild PS), the RV outflow gradient increased later in gestation. There was no change in the severity of tricuspid or pulmonary regurgitation during followup in any fetus. The severity of PS may be differentiated in utero by the direction of ductal flow, the presence of pulmonary insufficiency, severity of tricuspid insufficiency and the size of the pulmonary valve and PAs. In the absence of antegrade PA flow, severe PS may be difficult to distinguish from PAtr antenatally.

Anesthetic management for a palliative surgical procedure in a 72-year-old patient with tetralogy of Fallot

T ETRALOGY OF Fallot (TOF) is the most common form of congenital heart disease producing a right-toleft intracardiac shunt and arterial hypoxemia. The malformation consists of: (1) pulmonary artery outflow obstruction; (2) a large ventricular septal defect; (3) dextroposition of the aorta (biventricular origin or the aorta); and (4) right ventricular hypertrophy. Intracardiac repair of TOF is usually undertaken during infancy or childhood. However, some patients can reach adulthood without total correction or palliation. Indeed, case reports of patients surviving to the seventh decade of life have been reported. The oldest recorded patient with TOF was 69 years old,’ the oldest patient to have a total correction of TOF was 67 years old,2 and the oldest to undergo a systemic-pulmonary shunt for palliative operation for congenital heart disease was 22 years old.” The anesthetic management of a 72-year-old woman undergoing a modified right Blalock-Taussig shunt for palliation of TOF is reported.

Pulmonary vascular remodeling in rats with unilaterally banded lobar pulmonary veins

AbstractAlthough pulmonary vascular disease occurs in association with pulmonary venous obstruction, a model of pulmonary vascular lesions in this setting in small laboratory animals has yet to be described. The objective of this study was to determine if unilateral banding of pulmonary veins in the rat would produce pulmonary vascular disease that mimicked key aspects of the human disorder. Rats were anesthetized and, after mechanical ventilation and thoracotomy, one of the four pulmonary veins was banded to reduce its external diameter by approximately 65–75% to 0.8 mm. Additional animals, sham-operated controls, were treated identically except for venous banding. Mortality did not differ between groups and was less than 20%. Eight weeks after surgical preparation, moderate pulmonary hypertension was demonstrated with a mean pressure in the pulmonary artery of 24.9 mm Hg (range 19.25 – 30.0) in the banded group versus 18.7 mm Hg (range 16.6 – 19.3) for sham-operated animals. Pulmonary cineangiography in rats with banded pulmonary veins demonstrated marked pulmonary congestion and a prolonged residence time of contrast medium in the capillary circulation of the lung region subjected to banding. Angiographically, non-banded lungs were similar to shams. Histopathology of the vein-banded region revealed venous congestion, arterialization of veins, perivenular edema, and sparse to moderate inflammation. Prominent bronchial vessels, pulmonary arterial medial and occasional intimal thickening, and periarterial inflammation were also observed in banded regions. Similar inflammation around pulmonary arterial and pulmonary venous vessels was noted in contralateral lung lobes but not in sham-operated control rats. Morphometric evaluation of all muscular pulmonary arteries from 50–200μ external diameter accompanying airways to the level of terminal and respiratory bronchioles indicated that the medial area in lung regions subjected to venous banding was over three times greater than in shams. Pulmonary arteries from the contralateral, unbanded lungs of treated animals also exhibited a two-fold increase in medial area. These findings indicate that a modest degree of pulmonary venous banding in rats produces congestion and causes alterations in lung vessels which are reminiscent of those observed in humans with pulmonary venous outflow obstruction. Such a model in a cost-effective laboratory animal should be useful for delineating the specific mechanisms underlying these alterations.

Pediatric heart transplantation after operations involving the pulmonary arteries

A prohibitive perioperative mortality has been previously ascribed to pediatric heart transplantation after palliative operations for congenital heart disease involving the pulmonary arteries. Of 46 children who have undergone heart transplantation at our institution between June 1984 and February 1990, 7 (15%; mean age 8 +/- 3 years; range 1 to 18 years) have previously undergone such operations: right ventricle to pulmonary artery conduit/homograft for levo-transposition of the great arteries (2), Waterston shunt for tricuspid and pulmonary atresia (1), pulmonary artery banding for single ventricle (1), Fontan procedure for single ventricle (1), first-stage Norwood procedure for hypoplastic left heart syndrome (1), and classic right Blalock-Taussig shunt for atrioventricular canal with pulmonic stenosis (1). Three categories of pulmonary artery anatomy that require different approaches to reconstruction at the time of transplantation are recognized: abnormalities of position, pulmonary outflow obstruction, and previous systemic- or atrial-pulmonary connections. At operation, individualized pulmonary arterial reconstruction was employed, including use of previously created right ventricular-pulmonary artery conduits/homografts and angioplasty (with and without pericardial patches). Transplantation was successful in all patients. Posttransplant right ventricular-pulmonary artery pressure gradients and pulmonary vascular resistance indices were acceptable, with a tendency to decrease with time. Two patients had critical right ventricular failure postoperatively; one of them required support with extracorporeal membrane oxygenation. There was no perioperative mortality, with three deaths occurring from 5 to 39 months after transplantation. All surviving patients are in New York Heart Association functional class I. Techniques borrowed from the repair of congenital cardiac lesions can be applied to subgroups of children undergoing heart transplantation. Additional length of donor aorta and pulmonary artery should be harvested for possible use in designing pulmonary artery connections. Previous palliative operations involving the pulmonary arteries with associated complex pulmonary artery anatomy are not of themselves an insurmountable obstacle to successful heart transplantation.

Tricuspid valve disease with significant tricuspid insufficiency in the fetus: Diagnosis and outcome

The echocardiographic studies and clinical course of 27 fetuses (mean gestationl age 26.9 weeks) diagnosed in utero with tricuspid valve disease and significant tricuspid regurgitation were reviewed. The diagnosis of Ebstein's anomaly was made in 17 of the fetuses, 7 had tricuspid valve dysplasia with poorly developed but normally attached leaflets and 2 had an unguarded tricuspid valve orifice with little or no identifiable tricuspid tissue. One fetus was excluded from data analysis because a more complex heart lesion was documented at autopsy. All fetuses had massive right atrial dilation and most who were serially studied had progressive right-sided cardiomegaly. Hydrops fetalis was found in six cases and atrial flutter in five.Associated cardiac lesions included pulmonary stenosis in five cases and pulmonary alresia in six. Four fetuses with normal forward pulmonary artery flow at the initial examination were found at subsequent study to have retrograde pulmonary artery and ductal flow in association with the development of pulmonary stenosis (n = 1) and pulmonary atresia (n = 3). On review of the clinical course of the 23 fetuses (excluding 3 with elective abortion), 48% of the fetuses died in utero and 35% who were liveborn died despite vigorous medical and, when necessary, surgical management, many of whom had severe congestive heart failure. Of the four infants who survived the neonatal period, three had a benign neonatal course, all of whom were diagnosed with mild to moderate Ebstein's anomaly; only one had pulmonary outflow obstruction. An additional finding at autopsy was significant lung hypoplasia documented in 10 of 19 autopsy reports.Tricuspid valve anomalies with tricuspid insufficiency can be identified echocardiographically in the fetus and should be searched for in the presence of right atrial enlargement. The prognosis for the fetus diagnosed in utero with significant tricuspid valve disease is extremely poor, with a prenatal course that includes progressive right heart dilation, with cardiac failure and lung hypoplasia in many and development of pulmonary stenose or pulmonary atresia later in gestation in some.

Intermediate results of the arterial switch repair: A 20-institution study

A total of 466 neonates with transposition of the great arteries, all less than 15 days of age, have been entered into a 20-institution study between Jan. 1, 1985, and June 1, 1987. Seventy-three percent were less than 48 hours old when entered into the study. Two hundred twelve of these underwent an arterial switch repair, and the 1-week, 1-year, and 2 1/2-year survival rates were 82%, 79%, and 78%, respectively. The usual coronary anatomy was present in 67% of the patients. The arterial switch repair was performed in 16 of the institutions. Six among these were shown to be "low-risk" institutions, with the prevalence of the demographic and surgical variables seeming to be the same in these as in the other institutions. The 1-week, 1-year, and 2 1/2-year survival rates after the arterial switch repair in low-risk institutions for simple transposition were 96%, 91%, and 90%, respectively; for transposition with ventricular septal defect they were 84%, 83%, and 83%. Only older age at operation (over 14 days of age), in the case of simple transposition, and transposition with ventricular septal defect were risk factors for death in these six institutions. Among the patients as a whole, freedom from reoperation for pulmonary outflow obstruction at 1 week and 1 year was 99% and 89%, respectively. A previous pulmonary artery banding and, possibly, one institution were identified as risk factors for reoperation. Inferences: In low-risk institutions, the arterial switch repair can be accomplished with good early results, which suggests the possibility that the late results will be better than after the atrial switch repair. Since young age was not a risk factor for the arterial switch repair of transposition and ventricular septal defect, this type of repair for this anomaly, as well as for simple transposition, may be more advantageously performed early in life than at 2 to 3 months of age.

Long-term fate of valve cusp patches for right ventricular outflow tract reconstruction.

Six patients with tetralogy of Fallot, pulmonary atresia, or absent pulmonary valve syndrome were operated with a RVOT patch containing a single aortic allograft cusp from an adult donor. The method was based on animal work with similar patches implanted in growing puppies and proved that the single cusp functioned as an effective RV outflow valve for several weeks after surgery. Postoperative angiograms in the animals confirmed nearly completely competent valves. Sacrifice of animals at 3 months documented that the allograft tissue was flexible without early deterioration or calcification. Clinical application of this method raised several questions regarding the procedure, its efficacy, and subsequent fate of the allograft valve in children requiring RVOT reconstruction. There were six children age 19 months to 10 years who required division of the pulmonary valve annulus to relieve pulmonary outflow obstruction or with absent pulmonary valve syndrome and compromised airways from pulmonary insufficiency. One patient had a positive culture from the valve and required immediate removal of the infected allograft. Patients had clinically competent pulmonary valves immediately after surgery with decreased right ventricular systolic and end-diastolic pressures when compared with patients in whom nonvalve patches were inserted. All patients had some degree of pulmonary insufficiency, but no symptoms. Follow-up up of five patients available 4 to 6 years after surgery revealed no patients with stenosis of the valve cusps, although two patients have severe, one moderate, and two mild pulmonary insufficiency. We conclude that a patch containing a single adult allograft valve cusp should be considered for all patients requiring reconstruction of the RVOT, particularly if RV overload is expected to compromise the immediate postoperative result.

Noninvasive assessment of hemodynamic responses to exercise in pulmonary regurgitation after operations to correct pulmonary outflow obstruction

The influence of pulmonary regurgitation (PR) on exercise capacity is unknown. The hemodynamic responses to exercise in postoperative patients with PR was determined using Doppler-measured regurgitant fraction to indicate PR severity. Maximal heart rate, oxygen consumption and workload capacity were measured during upright cycle ergometry. Cardiac output was measured at rest and during submaximal supine cycle ergometry by pulsed Doppler echocardiography. Oxygen consumption was simultaneously measured and exercise factor was calculated as the change in cardiac output per change in oxygen consumption. Twenty-seven patients were compared with 17 age-, size- and sexmatched control subjects. Patients with PR had larger right ventricles (p ≤ 0.001), lower heart rate response (p ≤ 0.05), lower maximal oxygen consumption (p ≤ 0.005) and lower workloads (p ≤ 0.005) when compared with normal control subjects during maximal exercise testing. Exercise factor was the same for both groups. Patients with PR were then separated into mild, moderate and severe groups. Patients with mild PR had a normal response to exercise. However, patients with moderate and severe PR had lower maximal oxygen consumptions and maximal workloads than control subjects. Control, mild and moderate PR groups had similar exercise factors. Patients with severe PR had markedly low cardiac output responses. PR is associated with reduced exercise capability, which is related to the severity of the PR.

Balloon pulmonary valvotomy: Palliation for cyanotic heart disease

Balloon pulmonary valvotomy was attempted in eight children with cyanotic congenital heart disease and pulmonic stenosis who were scheduled for a palliative procedure (shunt). In seven patients the balloon could be positioned across the pulmonary anulus, and valvotomy was performed. Five of the patients had tetralogy of Fallot with multiple levels of pulmonary outflow obstruction. For all patients in whom the balloon could be properly positioned the valvotomy was successful, as judged by arterial hemoglobin saturation, which increased from 72% ± 5% to 83% ± 5% ( p < .005). Valvotomy was followed by an immediate rise in mean pulmonary artery pressure (12.6 ± 2.8 to 18.3 ± 4.8 mm Hg, p < 0.05) and a decline in hematocrit level at 2 months (54% ± 5% to 47% ± 4%, p < 0.05). There was no mortality or complication from the valvotomy, and the need for a systemic to pulmonary artery shunt was eliminated in six of eight patients. Follow-up has ranged from 0.5 to 2.8 years. This trial indicates that balloon pulmonary valvotomy can be safely performed and is effective palliation in selected patients with cyanotic heart disease that is not suitable for primary repair. The increased pulmonary flow may improve oxygenation and growth of the pulmonary arteries without the need of a systemic to pulmonary artery shunt.

Quantitative two-dimensional echocardiography in massive pulmonary embolism: Emphasis on ventricular interdependence and leftward septal displacement

In 14 patients requiring aggressive therapy for circulatory failure resulting from massive pulmonary embolism, hemodynamic and two-dimensional echocardiographic data were obtained at bedside (acute phase) and again after circulatory improvement (intermediate phase) and during recovery. The acute stage was characterized by a low cardiac output state despite inotropic support (cardiac index 1.9 +/- 0.6 liters/min per m2) associated with increased right atrial pressure (12.4 +/- 4.2 mm Hg), increased right ventricular end-systolic and end-diastolic area (12.4 +/- 3.4 and 15.4 +/- 4.1 cm2/m2, respectively) and reduced right ventricular fractional area contraction (20.1 +/- 8.6%). Two-dimensional echocardiography also revealed interventricular septal flattening at both end-systole and end-diastole and markedly decreased left ventricular end-diastolic dimensions. Left ventricular fractional area contraction remained normal. Hemodynamic improvement occurred during the intermediate phase as shown by restoration of cardiac index (3.3 +/- 0.6 liters/min per m2), decrease in right atrial pressure (8.3 +/- 4.8 mm Hg), reduction in right ventricular end-systolic area (9.0 +/- 3.6 cm2/m2 at the intermediate stage and 6.1 +/- 1.8 cm2/m2 at recovery) and end-diastolic area (10.5 +/- 3.6 cm2/m2 at the intermediate stage and 8.9 +/- 2.9 cm2/m2 at recovery) and improvement in right ventricular fractional area contraction (31.5 +/- 16.4%). The interventricular septum progressively returned to a more normal configuration at both end-systole and end-diastole, and left ventricular diastolic dimension steadily increased. It is concluded that circulatory failure secondary to massive pulmonary embolism was mediated through a profound decrease in left ventricular preload, resulting from both pulmonary outflow obstruction and reduced left ventricular diastolic compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Subpulmonary obstruction in congenitally corrected transposition of the great arteries due to ventricular membranous septal aneurysms.

The clinical, hemodynamic, and angiographic observations, as well as the surgical approach used for repair in three patients with congenitally corrected transposition of the great arteries and ventricular membranous septal aneurysms, are presented. In two of the three patients the membranous septal aneurysm caused subpulmonary obstruction, with 94 and 125 mm Hg systolic gradients. In each patient the aneurysm was demonstrated by angiocardiography, which also showed differences in size and shape with cardiac systole and diastole. Review of the previously described reports indicates that patients with congenitally corrected transposition often display various forms of pulmonary outflow obstruction and when a ventricular membranous septal aneurysm exists, a significant subpulmonary obstruction is present in most patients. The unique anatomic relationship between the pulmonary artery and a ventricular membranous septal aneurysm in patients with transposition of the great arteries with and without atrioventricular discordance explains why subpulmonary obstruction sometimes develops.

Clinical presentation of a myocardial rhabdomyosarcoma.

A case initially diagnosed as tricuspid insufficiency in which critical review of the clinical findings pointed to a diagnosis of pulmonary outflow obstruction is described. At necropsy a myocardial rhabdomyosarcoma was found with associated thromboembolism. The cardinal features were the rapid development of a loud systolic murmur, clinical evidence of right ventricular enlargement and failure with large jugular presystolic 'a' waves, and a reduction in the intensity of the pulmonary component of the second sound, a shift in the QRS axis to the right, and an increase in the cardiothoracic ratio.

Double outlet right ventricle with spontaneously developing pulmonary outflow obstruction.

<h3>Objective</h3> Patients with diabetes have an increased risk for urolithiasis, but the associated risk factors remain an active area of research. We investigated whether frailty influenced the probability of patients with diabetes developing urolithiasis. <h3>Research design and methods</h3> Using data from the Longitudinal Cohort of Diabetic Patients from 2004 to 2010, we identified those without and with frailty based on a validated, modified FRAIL scale. Patients were followed until they developed urolithiasis, and we used Kaplan-Meier and Cox proportional hazard regression analyses to examine the relationship between frailty, its severity, and the risk of urolithiasis, accounting for demographic profiles, comorbidities, frailty status changes over follow-up, and medications, with risk competition by mortality. <h3>Results</h3> Among 525 368 patients with diabetes, 64.4% were not frail, while 28.5%, 6.6%, and 0.6% had 1, 2, and ≥3 FRAIL items at baseline. After 4.2 years of follow-up, 13.4% experienced incident urolithiasis. Cox proportional hazard regression analysis showed that patients with diabetes having at least one FRAIL criterion exhibited a significantly higher risk for urolithiasis compared with non-frail patients (for 1, 2, and ≥3 items, hazard ratio (HR)s: 1.04, 1.23, and 1.46; 95% confidence intervals (CIs) 0.99 to 1.09, 1.12 to 1.35, and 1.12 to 1.91, respectively). This increase in urolithiasis risk remained significant if we restricted analyses to renal stones or recurrent urolithiasis as the study outcomes. <h3>Conclusions</h3> Frailty may pose a risk for incident urolithiasis in patients with diabetes. Treating frailty may potentially reduce their risk for urolithiasis.

Closure of ventricular septal defect and removal of pulmonary arterial band: Results in eight children

In a series of 8 patients pulmonary arterial banding was performed in infancy for large ventricular septal defect, and the defect was later operatively closed and the band removed. Hemodynamic evaluation was performed before banding, before corrective surgery and again at least 6 months after closure of the ventricular septal defect and removal of the pulmonary band. The hemodynamic data revealed successful closure of the ventricular septal defect in all cases. The pulmonary vascular resistance was at nearly normal levels in 3 patients, moderately increased in 4 and markedly increased in only the single patient banded late. As a consequence of the band, right ventricular or pulmonary outflow obstruction developed in 6 of the patients but was a significant problem in only 1 patient. Iatrogenic complications directly related to the presence of a pulmonary band are presented. Thickening of pulmonary valvular cusps with acquired secondary pulmonary valvular stenosis, although mild, occurred in 7 patients. Acquired infundibular pulmonary stenosis was also noted in 3 but was not of any hemodynamic significance. Some of these complications may be related to proximity of the band to the valve annulus. Despite these potential acquired complications, pulmonary arterial banding is considered a significant palliative procedure in the total treatment of excessive pulmonary blood flow and pulmonary hypertension.

Diagnosis and Surgical Treatment of Infants with Critical Pulmonary Outflow Obstruction

The records of 15 infants with pulmonary atresia and 19 infants with critical pulmonic stenosis and intact ventricular septum, all under 1 year of age, have been reviewed. Symptoms started earlier and were more severe in the group with pulmonary atresia. All patients showed arterial unsaturation, and many had congestive heart failure The electrocardiogram was the most helpful tool in differentiating pulmonary atresia from pulmonic stenosis with intact ventricular septum. The presence of P pulmonale, significant right axis deviation, and right ventricular hypertrophy favors pulmonic stenosis. At cardiac catheterization, patients belonging to both groups showed right ventricular hypertension of significant degree, but this was more marked in infants with pulmonic stenosis. Results of surgery for pulmonary atresia with intact ventricular septum, by a variety of methods, have been uniformly poor up to the present. Direct attack on the pulmonary outflow tract, when possible, may offer more promise for the future. Pulmonary valvotomy is the operation of choice for pulmonic stenosis and the results are good.