Clinical and hemodynamic effects of pulmonary artery banding

Right Ventricular Pressure Overload and Pathophysiology of Growing Porcine Biomodel

The primary objective was to create a clinically relevant model of right ventricular hypertension and to study right ventricular myocardial pathophysiology in growing organism. The secondary objective was to analyse the effect of oral enoximone (phosphodiesterase inhibitor) therapy on right ventricular haemodynamic parameters and myocardial changes in biomodel of right ventricular hypertension. The study included a total of 12 piglets of 42 days of age. Under general anaesthesia, pulmonary artery banding (PAB) was performed surgically to constrict the main pulmonary artery to about 70-80 % of its original dimension. The study presented two groups of animals labelled C (control animals with PAB; n = 8) and E (animals with PAB and oral administration of enoximone; n = 4). Direct pressure and echocardiographic measurements were taken during operation (time-1), and again at 40 days after surgery (time-2). The animals were killed, and tissue samples from the heart chambers were collected for quantitative morphological assessment. Statistical analysis was performed on all acquired data. At time-2, the median weight of animals doubled and the median systolic pressure gradient across the PAB increased (46.59 ± 15.87 mmHg vs. 20.29 ± 5.76 mmHg; p < 0.001). Changes in haemodynamic parameters were compatible with right ventricular diastolic dysfunction in all the animals. Apoptosis, tissue proliferation and fibrosis were identified in all the myocardial tissue samples. Right ventricular pressure overload leads to increased apoptosis of cardiac myocytes, proliferation and myocardial fibrosis. Our study did not show evidence of haemodynamic benefit or myocardial protective effect of oral enoximone treatment.

Vascular histopathologic reaction to pulmonary artery banding in an in vivo growing porcine model

Pulmonary artery banding (PAB) is used as a surgical palliation to reduce excessive pulmonary blood flow caused by congenital heart defects. Due to the lack of microscopic studies dealing with the tissue remodeling caused by contemporary PAB materials, this study aimed to assess histologic changes associated with PAB surgery by analyzing local tissue reaction to the presence of Gore-Tex strips fixed around the pulmonary artery. Gore-Tex strips were used for PAB in a growing porcine model. After 5 weeks, histologic samples with PAB (n = 5) were compared with healthy pulmonary arterial segments distal to the PAB or from a sham-treated animal (n = 1). Stereology was used to quantify the density of the vasa vasorum and the area fraction of elastin, smooth muscle actin, macrophages, and nervi vasorum within the pulmonary arterial wall. The null hypothesis stated that samples did not differ histopathologically from adjacent vascular segments or sham-treated samples. The PAB samples had a greater area fraction of macrophages, a lower amount of nervi vasorum, and a tendency toward decreased smooth muscle content compared with samples that had no PAB strips. There was no destruction of elastic membranes, no medionecrosis, no pronounced inflammatory infiltration or foreign body reaction, and no vasa vasorum deficiency after the PAB. All the histopathologic changes were limited to the banded vascular segment and did not affect distal parts of the pulmonary artery. The study results show the tissue reaction of palliative PAB and suggest that Gore-Tex strips used contemporarily for PAB do not cause severe local histologic damage to the banded segment of the pulmonary arterial wall after 5 weeks in a porcine PAB model.

Dilatable prosthesis for banding the main pulmonary artery: human clinical trials

The objectives of this trial are to assess the safety and effectiveness of the prosthesis and to establish the ability of the dilatable band to provide a nonsurgical option for dilatation. Forty-six patients received dilatable bands. All had congenital heart defects requiring banding of the main pulmonary artery. Dilatation was performed on 7 patients. This was successful in 6 and uncomplicated in all. In one patient the dilatable band was adjusted too tightly at implantation. In one patient the band was adjusted to loosely. In 7 patients the dilatable band was placed too distally and partially obstructed the right or left pulmonary artery. Distal migration of the dilatable band after implantation did not occur. One band was distorted during implantation. This did not compromise its function. Surgical sepsis resulted in a mycotic aneurysm and erosion of the pulmonary artery in one patient. Surgical pulmonary arterioplasty was performed in all 18 patients who had total correction and in 11 of the 13 patients who had bidirectional Glenn procedure and Damus-Stanzell connection. There were 13 deaths. None of the deaths were related to the dilatable band. Thirty-two prostheses were surgically explanted readily and completely in 31 patients. Five bands were removed at postmortem examination. Examination of all 37 of the dilatable bands revealed no evidence of wear or damage. Scanning electron microscopy evaluation was conducted on 5 of the explanted devices which had been implanted 158 to 1139 (mean 422) days. No component failure was identified. The dilatable band prostheses was effective and safe and provided a non-surgical option for dilatation.

Pseudoaneurysm of the pulmonary artery after the banding procedure: two-dimensional echocardiographic description

This report describes an infant with double-outlet right ventricle who underwent pulmonary artery banding as palliation for excessive left to right shunting through a ventricular septal defect. Three weeks after this procedure, there was abrupt clinical deterioration, and two-dimensional echocardiography clearly defined a large pseudoaneurysm arising from a breach in the posterior pulmonary artery wall, just proximal to the band. The diagnosis was confirmed at surgery, during which total correction was performed with successful outcome. The two-dimensional echocardiographic features of a pseudoaneurysm of the pulmonary artery are shown and the role of this noninvasive technique in the evaluation of pulmonary artery bands is discussed.

Echocardiographic assessment of the adequacy of pulmonary arterial banding

Thirty-one echocardiograms of 21 patients who had pumonary arterial banding were analyzed to assess the aequacy of surgery. In 5 patients the echocardiograms were obtained before and after banding and in 16 patients only after surgery. Right and left ventricular systolic time intervals were measured echographically. The ratios of the right ventricular preejection period to right ventricular ejection time (RPEP/RVET) were correlated with both diastolic (r = 0.94) and systolic (r = 0.86) pulmonary arterial pressures distal to the band. The analysis of right ventriclar systolic time intervals, especially the RPEP/RVET ratio, clearly differentiated patients with an adequate band (distal pulmonary arterial diastolic pressure less than 15 mm Hg) from patients with an inadequate band (distal pulmonary arterial diastolic pressure equal to or greater than 30 mm Hg). The results indicate that echocardiography is a useful noninvasive tool in evaluating the adequacy of the pulmonary arterial band and facilitates the follow-up of patients after banding.

Pulmonary artery banding: long-term results in 63 patients

Sixty-three patients who underwent banding of the pulmonary artery between 1968 and 1975 were studied. Mortality among patients who underwent the banding procedure was 22%, and among those with ventricular septal defect it was 7%. Thirty-eight of the 49 survivors of the banding procedure were investigated for abnormalities of the pulmonary outflow tract caused by the band. Seventy-one percent of these 38 patients had an identifiable abnormality of the pulmonary valve or artery. These complications occurred more frequently in patients banded at a very young age (less than 2 months old) and in patients in whom the band was in place more than two years. Corrective operations have been performed in 24 of the 49 patients who survived banding. Seventy-six percent of the patients with ventricular septal defect survived corrective operation, while only 29% of the patients with more complex lesions survived.

Truncus arteriosus and previous pulmonary arterial banding: clinical and hemodynamic assessment

Twenty-seven patients with truncus arteriosus and previous pulmonary arterial banding were evaluated 1 1/2 to 14 years (mean 7 years) after banding. Ages at the time of cardiac catheterization ranged from 3 to 18 years (mean 9 years). Current symptoms were severe in five patients and were related to truncal valve incompetence or decreased pulmonary blood flow (or both) rather than to age, duration of palliation or band location. Twenty-one of 22 patients with two pulmonary arteries were considered to be in a hemodynamically operable state at the time of study. The condition of three of five patients with a single pulmonary artery was subsequently found inoperable because of severe pulmonary vascular disease in the lung supplied by the single pulmonary artery. In patients with two pulmonary arteries, demonstration of low pressure in at least one normal-sized pulmonary artery established operability. Postoperative pressure measurements correlated well with preoperative prediction of operability, with 19 of 20 patients having a pulmonary arterial pressure less than 70 percent of systemic levels after repair. Bilateral pulmonary arterial binding may be more effective than central arterial banding (which frequently produces severe obstruction to the right pulmonary artery) in preventing pulmonary vascular obstructive disease in patients with truncus arteriosus who have two pulmonary arteries. Patients with truncus arteriosus and a single pulmonary artery with pulmonary arterial banding remain at high risk for the development of pulmonary vascular obstructive disease.

Hemodynamic effects of vasodilator agents in dogs with experimental ventricular septal defects

The ratio of pulmonary to systemic vascular resistance (Rp/Rs) largely determines the amount of left-to-right shunting and pulmonary to systemic flow rat (Qp/Qs) in the presence of a large isolated ventricular septal defect. The possibility that pharmacologic reduction of systemic vascular resistance with alpha-adrenergic receptor blockade or beta-adrenergic receptor stimulation would increase the ratio Rp/Rs, and therefore reduce the ratio Qp/Qs, was studied in dogs in which ventricular septal defects had been surgically created. Administration of phentolamine and phenoxybenzamine caused a 42% reduction in Rs and no reduction in Rp. Qs was unchanged and Qp declined by 24% and the ratio Qp/Qs fell by 32%. Infusion of the beta-adrenergic receptor stimulant isoproterenol also reduced Qp/Qs. However, this was accomplished as a result of an increase in Qs and at the expense of an increase in heart rate. As a decline in the ratio Qp/Qs has been shown to be beneficial to patients with large left-to-right shunts, pharmacologic reduction of systemic vascular resistance may prove to be helpful in treating congestive heart failure in those patients with large left-to-right shunts at the ventricular level who are refractory to the usual decongestive measures.

Second heart sound after pulmonary arterial banding operation

After a pulmonary arterial banding procedure the phonocardiograms of 38 patients were correlated with haemodynamic and angiographic findings. Twenty-four patients had uncomplicated ventricular septal defect, 2 had single ventricle, 5 had transposition of the great arteries, 5 had atrioventricular canal defects, and 2 had coarctation of the aorta and ventricular septal defect. P2 was separated from A2 by less than 40 ms in 10 of the 11 patients with high pulmonary vascular resistance. Of 27 patients with nearly normal pulmonary vascular resistances and distal pulmonary artery pressures less than 50/20 mmHg (6-7/2-7 kPa), 24 had A2-P2 intervals of over 40 ms. A narrow A2-P2 interval with a satisfactory band was found in 2 patients with large right-to-left shunts. A2-P2 interval did not change appreciably with age, and this measurement is a useful guide as to the effectiveness of pulmonary artery banding by one year after operation. If this interval is less than 40 ms, repeat catheterization should be carried out as such patients may have persisting pulmonary hypertension and an increased pulmonary vascular resistance.

The pulmonary artery lesion after banding: influence of differential materials

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Assessment of adequacy of pulmonary arterial banding by phonocardiogram

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Banding of the pulmonary artery. Results in 111 children

The results of banding of the pulmonary artery in 111 children with cardiac malformations associated with excessive pulmonary blood flow are presented. Thirty-three of these children died, eleven either of late band complications or after a corrective operation. Patients with ventricular septal defect represent the largest group of malformation among the 111 patients.

The overall mortality for banding in patients with isolated ventricular septal defect is 10%, as compared to 36% in patients with ventricular septal defect complicated by an associated lesion. In all infants with ventricular septal defect banded under age 3 months the mortality is 59%, as compared to a mortality of 21% in those banded after age 3 months and only 7% if banded after age 1 year. The overall mortality figures for pulmonary arterial banding have not changed appreciably since 1966; future improvement in banding mortality will depend on improved postoperative management of these infants.

Serial hemodynamic studies in patients banded under the age of 2 years have shown a fall in the pulmonary resistance toward normal, with none showing a progression of pulmonary vascular disease. In several patients thickening of the pulmonary valve occurred as a complication of banding.