Hilar Artery Research Articles

Complex renal vascular variation: A case report

As the number of renal surgical interventions increase a better understanding of the anatomy of renal arteries and their branches gain in importance. Here we describe a common trunk from the right side of the aorta ramifying into suprarenal and two renal hilar arteries in a 40-year-old male cadaver detected during dissections performed in a routine gross anatomy course. The suprarenal branch is divided into several smaller branches to supply blood to the suprarenal gland. The superior renal hilar artery gave rise to the right testicular artery and an additional suprarenal artery. The inferior renal hilar artery gave rise to one more additional suprarenal artery. The superior renal hilar artery crossed the inferior renal hilar artery. On the same side renal veins were also doubled. For better outcome interesting variations such as in this case should be kept in mind before and during any interventions involving this region.

A New Clinical Model in Pulmonary Embolism and Its Correlation With V/P Scan Results

The study was prospectively designed to assess the correlation between a new clinical model empirically developed for acute pulmonary embolism (PE) and ventilation/perfusion (V/P) scan results. One hundred sixty consecutive patients with suspected acute PE underwent clinical evaluation before V/P scintigraphy. The clinical probability of PE was categorized according to a structured clinical model empirically developed as low, intermediate, or high, and the results were compared with those of V/P scintigraphy. Forty, 61, and 59 patients were classified as low, intermediate, and high clinical probability, respectively. Seventy-five percent (30/40) of the patients with low clinical probability were also of low scintigraphic probability or had a normal result (r(s): 0.39, p=0.000); 28% (17/61) of the patients with intermediate clinical probability demonstrated intermediate scintigraphic probability (r(s): 0.20, p=0.012); and 68% (40/59) of the patients with high clinical probability were also of high scintigraphic probability (r(s): 0.43, p=0.000). Overall, the correlation of two scoring systems was statistically significant (r(s): 0.39, p=0.000). Unilateral leg swelling (p=0.027), syncope or near syncope (p=0.002), amputation of a hilar artery (p=0.007), and electrocardiographic signs of right ventricular overload (p=0.000) prevailed in patients with high scintigraphic probability. "Syncope-near syncope or hemodynamic collapse" PLUS "electrocardiographic signs of right ventricular overload or hypoxemia" combination had the most significant correlation with a high scintigraphic probability (r(s): 0.31; p=0.000). In conclusion, the new clinical model empirically developed was significantly successful to provide comparable results with V/P scan. This consistency was particularly prominent in patients with low or high clinical probability for PE.

Renovascular Hypertension and Double Renal Arterial Supply Diagnosed by Tc-99m MAG3 Captopril Renography

Renovascular hypertension is the most frequent secondary cause of hypertension (0.5–2%). Captopril renal scintigraphy is safe, noninvasive, and effective in the detection of renovascular hypertension. Positive captopril renography may suggest a cure of hypertension and improvement in renal function with successful renal revascularization. The authors report the case of successful detection of renovascular hypertension by captopril renal scintigraphy in a patient with 2 hilar renal arteries. Revascularization of the stenosed hilar artery was obtained by transluminal angioplasty and stent placement, leading to rapid control of the hypertension.

An investigation of the origin, location and variations of the renal arteries in human fetuses and their clinical relevance

We investigated the origin, localizations and anatomic variations of the renal artery (RA) in human fetuses with the aim of determining the distribution of these variations according to lateralization and gender. In total, 90 fetuses of spontaneous abortion (45 males, 45 females) with no congenital malformations were included to the study. The abdominal aorta and its branches were dissected after latex solution colored with red ink had been injected into the vessels from the thoracic aorta. In all, 180 RA dissections were performed bilaterally in 90 cases and the anatomic variations were photographed. Right and left RAs were found to originate from the following levels according to the columna vertebralis, respectively: 3.8% and 1.9% lower T12, 67.3% and 25.0% upper L1, 9.6% and 28.8% mid L1, 15.3% and 40.3 lower L1, 3.8% and 3.8% upper 1/3 part of L2 vertebra. The right RA originated from the lateral part and anterolateral wall of the abdominal aorta in 73.0% and 26.9% of cases while the lateral and anterolateral wall origin percentages of left RA were 90.3% and 9.6%, respectively. The origin site of the right RA from the abdominal aorta was superior to, at the same level with, and inferior to that of the left RA in 53.8%, 34.6% and 11.5% of the cases, respectively. There were no variations in 75% of the cases whereas the remaining 25% had several variation patterns. The presented morphological results are as follows: A single hilar artery in 75% of the cases, double hilar arteries in 11.1%, an inferior polar artery in 10.5%, and a superior polar artery in 3.3% of specimens studied. Anatomical variations were observed more frequently among male fetuses and on the right side. Knowledge of RA variations is important for surgeons in performing many procedures and may help to avoid clinical complications, especially, during radiological examination and/or surgical approaches in the abdominal region.

Anatomy of renal arterial supply

A thorough knowledge of the variations of the renal artery has grown in importance with the increasing numbers of renal transplants, vascular reconstructions, and various surgical and radiologic techniques. The literature indicates that multiple renal arteries are found in 9- 76% of cadavers. The purpose of this study is to establish the incidence and characteristics of variations of renal arteries in Thais. A total of 267 Thai cadavers were dissected in the anatomy laboratory. The anatomical findings included: a single hilar artery in 82% of cases; double renal arteries in 17% of cases (one hilar artery with an upper polar artery occurred in 7%; two hilar arteries in 7%, and one hilar artery combined with one lower polar artery in 3%); and triple renal arteries occurred in 1% (two hilar arteries with one upper polar artery in 0.4% and two hilar arteries with one lower polar artery in 0.6%). In preparation for interventions, such as living renal donation, vascular reconstruction, renovascular hypertension, or radical nephrectomy, the results indicate that preoperative renal imaging is necessary and that operative techniques with attention to multiple renal arteries should be considered.

A structured clinical model for predicting the probability of pulmonary embolism

Purpose To develop a structured model to predict the clinical probability of pulmonary embolism. Methods We studied 1100 consecutive patients with suspected pulmonary embolism in whom a definite diagnosis had been established. We used logistic regression analysis to estimate the probability of pulmonary embolism based on patients’ clinical characteristics; the probability was categorized as low (≤10%), intermediate (>10%, ≤50%), moderately high (>50%, ≤90%), or high (>90%). Results The overall prevalence of pulmonary embolism was 40% (n = 440). Ten characteristics were associated with an increased risk of pulmonary embolism (male sex, older age, history of thrombophlebitis, sudden-onset dyspnea, chest pain, hemoptysis, electrocardiographic signs of acute right ventricular overload, radiographic signs of oligemia, amputation of the hilar artery, and pulmonary consolidation suggestive of infarction), and five were associated with a decreased risk (prior cardiovascular or pulmonary disease, high fever, pulmonary consolidation other than infarction, and pulmonary edema on the chest radiograph). With this model, 432 patients (39%) were rated a low probability, of whom 19 (4%) had pulmonary embolism; 283 (26%) were rated an intermediate probability, of whom 62 (22%) had pulmonary embolism; 72 (7%) were rated a moderately high probability, of whom 53 (74%) had pulmonary embolism; and 313 (28%) were rated a high probability, of whom 306 (98%) had pulmonary embolism. Conclusion This prediction model may be useful for estimating the probability of pulmonary embolism before obtaining definitive test results.

Cirugía sin arteriografía de los troncos viscerales

Summary Aims The aim of this paper is to describe the advantages and disadvantages of Doppler ultrasound (DUS), computerised tomographic angiography (CTA) and magnetic resonance angiography (MRA) in the study of lesions in the visceral trunks (VT), in comparison with digital subtraction arteriography (DSA), according to the medical literature published to date. Development DUS allows the presence of stenosis in the VT to be detected, with a sensitivity of between 90 and 95% and a specificity of between 85 and 90%. Its main limitations are the variability depending on the operator's experience and on the anatomical characteristics of the patient. CTA is a good test for detecting thepresence of stenoses in the renal arteries and mesenteric trunks (MT), although few comparative studies have been performed on the subject. Its chieflimitations are the inadequate measurement of the degree of stenosis in severe stenoses and the need to use a nephrotoxic contrast. 3D contrast MRA (MRA 3D) seems to be the ideal test in vascular studies with MR. The use of non-ionising radiations andcontrastsfree of nephrotoxic effects are two of the advantages of MRA compared with DSA or CTA. MRA offers a sensitivity of between 88 and 100%, and a specificity of between 71 and 100% in the study of renal arteries. Like CTA, it displays a tendency to overestimate the degree of stenosis. The DUS, CTA and MRA all offer low sensitivity and specificity in the study of arterial lesions in polar arteries and in the hilar renal artery. Conclusions DUS is a sensitive test that is relatively cheap and accurate enough for use as a screening test in the study of stenoses in the VT, but little work has been published in which DUS are employed as a single diagnostic tool to indicate a renal or mesenteric revascularisation. The value of CTA in the study of the renal artery and of the MT will have to be proved by means of double-blind studies that compare it with DUS. Until the appearance of these studies, it must be considered to be a screening test or a technique to complement DUS. MRA is a good test for diagnosing stenosis of the renal artery, with a similar sensitivity and specificity to those of DUS. At the same, it offers the possibility of determining the functional repercussions of the arterial lesion. MRA is also a technique that has obtained similar results to those offered by DUS in the study of the main MT. We will, however, probably have to wait for the results of double-blind tests carried out with large numbers of patients before we can accept MRA as a single diagnostic test in MT lesions.

Isolated Unilateral Absence of a Pulmonary Artery: A Case Report and Review of the Literature

The purpose of the present study was to determine the symptomatology, diagnostic procedures, and therapeutic strategies of patients with an isolated unilateral absence of a pulmonary artery (UAPA). Isolated UAPA is a rare anomaly. Some case reports exist, but the best diagnostic and therapeutic approaches to these patients remain unclear. A retrospective analysis was made of 108 cases reported between 1978 and 2000. The database of the National Library of Medicine (MEDLINE) was used to identify cases that were published in any language from 1978 onward. Of the 108 patients identified, 14 were asymptomatic. The median age was 14 years (range, 0.1 to 58 years). Most patients had symptoms such as frequent pulmonary infections (37%), dyspnea or limited exercise tolerance (40%), or hemoptysis (20%). Pulmonary hypertension was present in 44% of the patients. Surgical procedures were performed in 17% of patients, and the overall mortality rate was 7%. Only a few patients with isolated UAPA remain asymptomatic during follow-up. The diagnosis can be made by chest radiograph, echocardiography, CT scan, and MRI. Hilar arteries can be shown by cardiac catheterization and pulmonary venous wedge angiography. This is important since revascularization may improve pulmonary hypertension. The avoidance of high altitudes and pregnancy may further improve outcomes.

Surgical injuries occurring during kidney procurement performed by a renal transplantation team

ENAL surgery injuries, which sometimes occur during organ procurement, may contribute to morbidity and renal function impairment as well as increased hospital stay and cost. 1 In France, renal procurements are customarily performed by urologists directly involved in renal transplantation, who also have to deal with transplant complications. Prevention is the best way to manage renal surgery injuries, but this requires identifying the manner in which they may occur. The purpose of the present study was to clarify the causes of renal injuries during organ harvests over the past 15 years at our institution. PATIENTS AND METHODS Between 1985 and 2000 we performed 627 renal procurements (191 female and 436 male donors) including 558 from heart-beating and 69 from non– heart-beating donors. We noted the surgical injuries to the kidneys and the causes cited by physicians for not using organs. Statistical analysis was performed according to initial injury assignments based on our database. The chi-square test was used as appropriate; differences were considered statistically significantly if P .05. RESULTS A total of 1239 kidneys were harvested. Fifteen kidneys were not harvested. There were 106 kidneys not transplanted. The presence of surgical lesions was the reason for transplant refusal in four cases (1 renal decapsulation, 1 arterial injury, and 2 venous injuries, which could not be repaired properly). Twenty kidneys were refused for transplantation because they were macroscopically abnormal, namely a renal tumor or renal rupture, or because they displayed microscopic abnormalities, namely nephroangiosclerosis, glomerulosclerosis, or arteriolar injuries. Macroscopic surgical arterial injuries were observed in 2.3% (29 of 1254) of cases (26 polar artery transections and 3 hilar artery transsections). Venous lesions were observed in 0.5% (7 of 1254) of cases. Surgical injuries were more frequently observed during single-organ procurements than during multiorgan procurements: 8.2% vs 3.7%, respectively (P .05). Similarly, injuries were more frequent during non– heart-beating donor procurement: 9.3% vs 4.6% (P .01), or when the surgeon had less training (30 organ vs 30 procurements): 12% vs 3%, respectively (P .01).

Inhibition of NOS enhances pulmonary vascular changes in stroke-prone spontaneously hypertensive rats.

To determine the effects of chronic nitric oxide (NO) blockade on the pulmonary vasculature, 58-day-old spontaneously hypertensive rats of the stroke-prone substrain (SHRSP) and Wistar-Kyoto rats (WKY) received N(omega)-nitro-L-arginine (L-NNA; 15 mg. kg(-1). day(-1) orally for 8 days). Relaxation to acetylcholine (ACh) in hilar pulmonary arteries (PAs), the ratio of right ventricular (RV) to body weight (RV/BW) to assess RV hypertrophy (RVH), and the percent medial wall thickness (WT) of resistance PAs were examined. L-NNA did not alter the PA relaxation, RV/BW, or WT in WKY. Although the PA relaxation and RV/BW in control SHRSP were comparable to those in WKY, the WT was increased (31 +/- 2 vs. 19 +/- 1%). L-NNA-treated SHRSP showed two patterns: in one group, the relaxation, RV/BW, and WT were comparable to those in the control SHRSP; in the other, impaired relaxation (36 +/- 7 vs. 88 +/- 4% for WKY) was associated with an increase in WT (37 +/- 1%) and RV/BW (0. 76 +/- 0.05). Thus the abnormal pulmonary vasculature in SHRSP at <10 wk of age is not accompanied by impaired relaxation in PAs or RVH; however, impaired relaxation is associated with increased WT and RVH.

Arterial elastorrhexis: manifestation of a generalized elastic tissue disorder in beta-thalassaemia major.

Pseudoxanthoma elasticum-like lesions of the eye and skin are frequently observed in beta-thalassaemia, and there has been speculation about associated vascular lesions. This led to our study of histopathological material from thalassaemic patients. Histological re-examination was made of a series of 45 spleens and 45 surgical liver biopsies from 45 patients with beta-thalassaemia major, aged 6-25 yr and treated over the 20-yr period 1975-95. Correlations between clinical, laboratory and histological findings were demonstrated by statistical analysis. Arteriopathy characterized by fragmentation and multiple defects of the internal elastic lamina ('arterial elastorrhexis'), with deposits of iron and calcium salts, was found in the hilar arteries of the spleen with a frequency of 96%. Similar lesions were observed in the parenchymal arteries and the stromal elastic tissue ('stromal elastorrhexis') of the spleen, liver and lymph nodes. Arterial and elastic tissue alterations appear in the first decade of life and become generalized over the course of the disease, independent of the time of onset of transfusion and iron chelation therapy. Arterial elastorrhexis is the earliest and most frequent manifestation of a systemic elastic tissue disorder in beta-thalassaemia major. It appears to be an acquired pseudoxanthoma elasticum-like syndrome, related primarily to tissue hypoxia and disturbance of elastin metabolism.

Accuracy of clinical assessment in the diagnosis of pulmonary embolism.

To provide clinical diagnostic criteria for pulmonary embolism (PE), we evaluated 750 consecutive patients with suspected PE who were enrolled in the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA-PED). Prior to perfusion lung scanning, patients were examined independently by six pulmonologists according to a standardized diagnostic protocol. Study design required pulmonary angiography in all patients with abnormal scans. Patients are reported as two distinct groups: a first group of 500, whose data were analyzed to derive a clinical diagnostic algorithm for PE, and a second group of 250 in whom the diagnostic algorithm was validated. PE was diagnosed by angiography in 202 (40%) of the 500 patients in the first group. A diagnostic algorithm was developed that includes the identification of three symptoms (sudden onset dyspnea, chest pain, and fainting) and their association with one or more of the following abnormalities: electrocardiographic signs of right ventricular overload, radiographic signs of oligemia, amputation of hilar artery, and pulmonary consolidations compatible with infarction. The above three symptoms (singly or in some combination) were associated with at least one of the above electrocardiographic and radiographic abnormalities in 164 (81%) of 202 patients with confirmed PE and in only 22 (7%) of 298 patients without PE. The rate of correct clinical classification was 88% (440/500). In the validation group of 250 patients the prevalence of PE was 42% (104/250). In this group, the sensitivity and specificity of the clinical diagnostic algorithm for PE were 84% (95% CI: 77 to 91%) and 95% (95% CI: 91 to 99%), respectively. The rate of correct clinical classification was 90% (225/250). Combining clinical estimates of PE, derived from the diagnostic algorithm, with independent interpretation of perfusion lung scans helps restrict the need for angiography to a minority of patients with suspected PE.

Solitary arterial trunk

AbstractA heart is described in which there was a solitary arterial trunk that exited from the heart astride a large perimembranous ventricular septal defect, with the pulmonary arterial supply originating entirely from collaterals from the descending aorta. There was no evidence of either hilar pulmonary arteries or an atretic pulmonary trunk. The morphology of the ventricular outlet component, with absence of the outlet septum supports the description of this heart as solitary arterial trunk, rather than tetralogy of Fallot with pulmonary atresia.

A Scanning Electron Microscope Study of the Human Cervical Lymph Node

Arterial casts of human cervical lymph nodes were studied using scanning electron microscopy. Human cervical lymph nodes appear to be much more complex and dense than their animal counterparts. Human lymph nodes have a separate medulla arising from the hilar artery complex and cortical structure derived from capillaries. Also present is a previously unknown rosette formation of blood vessels. The possible implications of these findings for inflammatory and neoplastic diseases are discussed.

Renal arteries: anatomic study for surgical and radiological practice.

The renal arterial supply was analyzed in 266 kidneys dissected from 133 fixed adults subjects. The anatomical findings are presented: 1 hilar artery in 53.3% of the cases, 1 hilar artery with 1 superior pole extra-hilar branch in 14.3%, 2 hilar arteries in 7.9%, 3 hilar arteries in 1.9%, superior polar artery in 6.8%, inferior polar artery in 5.3% and other variations in 8.5%. The urological and radiological implications of these findings in kidney transplantation, renovascular hypertension, renal trauma, interventional radiology, conservative surgery and oncologic surgery are discussed.

Blood vasculature of the lymph node in the dog: anatomical evidence for participation of extrahilar arterial vessels in the blood supply of the cortex.

The organization of the arterial vessels of dog lymph nodes (LN) was studied using methods of visualization of the vasculature by systemic injection of different tracers (colloidal carbon, Micropaque resin and methylmethacrylate) followed by observation of the samples by light microscopy (after clearing of the thick sections of LN) or scanning electron microscopy (corrosion casts). LN from all of the three groups of nodes studied (tracheobronchial, paratracheal and popliteal) showed an extensive network of arterial vessels encircling the capsule of the organ. We found that branches of these capsular arteries penetrated deeply into the cortical domain of LN. The capsule-originating vessels appeared to have a significant participation in the blood supply of the LN parenchyma at the cortical domains of the organs. Our findings are in contrast with current views on the angiology of the LN that consider that virtually all of the arterial capillaries of the LN parenchyma come from hilar arteries. We propose, therefore, that important segments of the LN cortex receive their blood supply from capsular arteries rather than from hilar vessels.

Inhibition of elastolysis by SC-37698 reduces development and progression of monocrotaline pulmonary hypertension

Our previous studies showed that increased pulmonary artery elastolytic activity is associated with monocrotaline-induced pulmonary hypertension in rats, and the latter is reduced by the elastase inhibitor SC-39026. This agent, given orally, decreases monocrotaline-induced muscularization of normally nonmuscular peripheral arteries but not medial hypertrophy of muscular arteries. To establish whether constant infusion of an elastase inhibitor would reduce both vascular lesions induced by monocrotaline injection, SC-37698 (an analogue of SC-39026) was given intravenously by osmopump. To separately assess whether SC-37698 would inhibit development of the vascular changes as well as their progression, SC-37698 or vehicle was infused for the first 2 wk (2-wk study) or was delayed until 1 wk after monocrotaline injection (3-wk study). Hemodynamic data were recorded from indwelling catheters, and the lungs were evaluated morphologically. Saline-injected control rats given SC-37698 or vehicle were similar at both time points. Monocrotaline-injected rats given SC-37698 compared with those given vehicle alone had lower pulmonary artery pressures, 17.9 +/- 0.5 vs. 23.7 +/- 0.8 mmHg (P less than 0.01) in the 2-wk study and 24.0 +/- 1.8 vs. 33.5 +/- 3.1 mmHg (P less than 0.05) in the 3-wk study. This was associated with significant decreases in muscularization of peripheral arteries and reductions in medial hypertrophy of muscular arteries. In the hilar pulmonary arteries assessed at 3 wk only, SC-37698 significantly decreased monocrotaline-induced endothelial injury, subendothelial edema, migration of smooth muscle cells into subendothelium, medial hypertrophy, collagen accumulation, and abnormal distribution of elastin as interlamellar islands. Pulmonary artery elastolytic activity was reduced in SC-37698-treated compared with untreated monocrotaline-injected rats (P less than 0.05). Thus infusion of SC-37698 reduces monocrotaline-induced pulmonary hypertension when administered before or even after development of early vascular changes.

The kidney of tapirs: A macroscopical study

The renal cortex of tapirs, water-loving primordial ungulates, was continuous, nonlobed, and about 80% of renal mass in adult and 71% in term-neonate. In the neonates even the peripheral glomeruli were moderately mature. Tapirus bairdi had about 4 million glomeruli per kidney and T. pinchaque about 3 million smaller glomeruli. Number of glomeruli per gm of cortex was 12,444 in T. bairdi and 13,400 in T. pinchaque. Cortical loops were common in the medullary rays. The medulla was the simple crest-type. The terminal collecting ducts (T.C.D.) opened separately at the crest and not into a tubus maximus. The "outer stripe" of the outer medulla apparently was telescoped into the deep cortex. The medullary loops turned at a thick portion and at nearly all levels of the medulla. The medullary crest was lined by urothelium which extended into the ends of the T.C.D. Otherwise the T.C.D. were made of columnar epithelium. The pelvic urothelium was continuous with that of the medullary crest at the dorsal and ventral fornices. The fornices were well within the inner medulla. Hence only inner medulla could be exposed to pelvic urine. The hilar arteries, unlike the other two perissodactyl families (rhinoceri and equids), passed through the cortico-medullary (C-M) border and some large arteries and veins passed through the outer medulla to and from the C-M border without branches or tributaries. Unlike kidneys with a medullary crest in diverse eutherian mammals, tapirs lacked pelvic extensions along the major intrarenal blood vessels and thus lacked pelvic intervascular eminences.

SGP-2 expression as a genetic marker of progressive cellular pathology in experimental hydronephrosis

The onset of hydronephrosis following unilateral ureteral obstruction is associated with the induced expression of RNA and proteins encoded by the SGP-2 gene. SGP-2 expression has been shown to demarcate mammalian cells undergoing apoptosis. Using in situ hybridization, the cellular localization of SGP-2 expression in the obstructed kidney was determined as a means to study the various phases involved in the progression of hydronephrosis. Within 30 minutes of obstruction, SGP-2 mRNA expression was localized to the adventitial layers of the hilar arteries and intrarenal arterioles. Increasing time of obstruction resulted in the notable absence or depletion of this layer. In addition, the pattern of SGP-2 expression changed with time to the collecting ducts and distal tubules. This study identifies the vascular support tissue of the kidney as the initial site of reaction and potential cell death following ureteral obstruction. We believe that this observation may be of importance in explaining the early alterations in blood flow associated with hydronephrosis.

Surgical factors affecting growth potential of the immature rat lung

The transplanted immature rat lung has been shown capable of fulfilling its growth potential after left lung transplantation (LLTx) and concomitant right cardiac lobe resection (RCLR). However, unexpected findings in these studies included an abnormal rise in lung volume in the contralateral lung due to alveolar multiplication, and significant dilatation of the bronchi in the transplanted left lung. In the present study, the influence of surgical factors that could have contributed to these changes, i.e. RCLR, denervation, and anastomotic stenosis, were studied individually. Immature Lewis rats aged 4 and 6 weeks were used and (a) RCLR, (b) RCLR and right hilar stripping, and (c) RCLR and left pulmonary artery (PA) banding were performed in groups 1 (n = 12), 2 (n = 5) and 3 (n = 6), respectively. Animals were killed after 6 months and the lungs studied using quantitative morphometric techniques. In groups 1 and 2, right lungs did not show any significant increase in volume. Alveolar number and airway diameter in both lungs in all groups were not significantly different from controls. In group 3 both right and left lungs presented an increase in alveolar size (p less than 0.02 on the right and p less than 0.01 on the left). Changes seen after LLTx in the rat, such as alveolar multiplication, cannot be explained by compensatory growth (RCLR), denervation (RCLR and hilar stripping), or arterial stenosis at the anastomotic site (RCLR and left PA banding), but must be regarded as a consequence of transplantation per se. A role for neuropeptides in lung growth following transplantation is suggested.