Antiarrhythmic action of naloxone. Suppression of picrotoxin-induced cardiac arrhythmias in the rat

The antiarrhythmic properties of the opiate antagonist naloxone have been reported in a variety of models of arrhythmia. To determine the generality and the possible central involvement of its antiarrhythmic activity, the effects of naloxone were assessed against cardiac arrhythmias induced by intravenous bolus injections of picrotoxin. Naloxone at doses of 0.33 and 1 mg/kg significantly reduced the incidence and severity of picrotoxin-induced arrhythmias in a dose-related manner, without alteration of blood pressure and heart rate. The results demonstrate the antiarrhythmic efficacy of naloxone in an additional animal model. They further suggest that the antiarrhythmic actions of naloxone may be mediated by the central nervous system via both the autonomic and GABAergic pathways.

Consequences of opiate agonist and antagonist in myocardial ischaemia suggest a role of endogenous opioid peptides in ischaemic heart disease

OBJECTIVE

The aim was to evaluate the effects of an opiate agonist (U50,488H) and an opiate antagonist (naloxone) in myocardial ischaemia.

METHODS

A left thoracotomy was performed and the left coronary artery was ligated in adult Sprague-Dawley rats of either sex (350-400 g). Blood pressure, heart rate and electrocardiogram were measured before and after injections of U50,488H or naloxone and throughout the 30 min postligation period.

RESULTS

Following coronary artery occlusion, all rats in the control group developed arrhythmias, bradycardia, and hypotension. U50,488H potentiated and naloxone attenuated the ischaemia induced arrhythmias, bradycardia, and hypotension.

CONCLUSIONS

The potentiating and blocking effects of U50,488H and naloxone, respectively, suggest that endogenous opioid peptides are involved in the pathophysiology of myocardial ischaemia and play an important role in ischaemic heart disease.

Prenatal diagnosis of Pompe's disease (type II glycogenosis) in chorionic villus biopsy using maltose as a substrate

Uncultured trophoblasts obtained from chorionic villus biopsy during the gestation period of 8-12 weeks were assayed for alpha-glucosidase activity using maltose as the substrate. Only one major form of maltase activity with a pH optimum at 4.0 was demonstrated. Using this method, we performed prenatal diagnosis on three pregnancies at risk for the infantile form of type II glycogen storage disease. Two affected fetuses and one unaffected fetus were predicted and the diagnosis was subsequently confirmed. The maltose assay offered a direct, simple, and sensitive method for prenatal diagnosis of Pompe's disease in the first trimester.

Cytomegalovirus infection of renal allografts. Detection by polymerase chain reaction

Early laboratory diagnosis of acute cytomegalovirus infection in renal transplant recipients is desirable but often difficult. The polymerase chain reaction (PCR) technique for detecting CMV DNA, although it promises a high sensitivity, risks the possibility of detecting latent CMV infection and leading to false-positive results. To address this issue and the feasibility of applying PCR to renal biopsy specimens, we analyzed 37 renal allografts by PCR. Formalin-fixed or Bouin-fixed paraffin-embedded materials were employed, and primers from the LA (late-antigen) region of CMV were used. Amplified products were detected by gel electrophoresis and ethidium bromide staining, followed by Southern blot analysis. Of 21 nephrectomy samples, three showed CMV-specific amplified products by PCR, but CMV inclusion bodies were detected histologically in only one of the three. Of 16 renal biopsies, three specimens were positive by PCR, with rare viral inclusions histologically identified in only one. All PCR-positive patients had clinically significant CMV disease as evidenced by positive CMV culture and/or seroconversion. In contrast, all CMV-seropositive patients without active viral disease had PCR-negative allografts. We conclude that PCR positivity in the renal allograft strongly correlates with active CMV disease but not latent infection. For the diagnosis of active CMV disease in patients with a renal allograft, PCR provides a means that is more sensitive and objective than histologic examination, more specific than serology, and faster than viral culture.

Identification of a new mutation in medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

A mutation involving an A-to-G nucleotide replacement at position 985 of the medium-chain acyl-CoA dehydrogenase (MCAD) cDNA was found in homozygous form in 18 unrelated MCAD-deficient families and in heterozygous form in 4 families. By PCR amplification and sequencing of cDNA from a compound heterozygote, we have detected a new mutation in an MCAD-deficient patient in whom one MCAD allele produces mRNA that is missing 4 bp in the MCAD cDNA, while the other allele carries the A-to-G-985 mutation. The presence of this 4-bp deletion was confirmed in the patient's genomic DNA by dot-blot hybridization with allele-specific oligonucleotide probes and by restriction analysis of PCR products. A rapid screening test for this 4-bp deletion was developed, based on mismatched primer PCR amplification. The deletion created a new restrictive-enzyme site which yielded two DNA fragments. The 4-bp deletion was not found in the three remaining MCAD chromosomes not harboring the A-to-G-985 mutation, nor it was present in 20 chromosomes from 10 unrelated normal Caucasians. The PCR-based method for screening these two mutations can detect over 93% of all MCAD mutations.

Glycogen debranching enzyme deficiency: long-term study of serum enzyme activities and clinical features

In glycogen storage disease type III (glycogen debranching enzyme (DE) deficiency), the activities of serum alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase may be strikingly elevated during childhood but are low during adult life. To determine the pattern of the elevated serum enzyme activities in relationship to diet, the biochemical subtype and clinical symptoms, 13 patients with DE deficiency were studied. Activities of serum aspartate and alanine transaminases, lactate dehydrogenase, and alkaline phosphatase were markedly elevated during infancy. Continued elevation of enzyme activities during childhood appeared to be related to DE deficiency in liver, but unrelated to DE deficiency in muscle. Activity elevations correlated inconsistently with diet and poorly with childhood growth rate or the presence of hypoglycaemia. The serum enzyme activities declined around puberty concomitantly with a decrease in liver size. Although periportal fibrosis and micronodular cirrhosis indicated the presence of hepatocellular damage during childhood, the decline in serum enzyme activities with age and the absence of overt hepatic dysfunction suggest that the fibrotic process may not always progress.

Immunohistochemistry and gene rearrangement studies in the diagnosis of malignant lymphomas: a comparison of 152 cases

One hundred fifty-two cases (155 specimens) of lymphoproliferative disorders were studied by immunohistochemistry and gene rearrangement analysis. Ninety-five of 96 B-cell lymphomas (99%) showed genotypic B-cell monoclonality. Of these, five cases had rearranged T-cell receptor (TCR) beta chain gene in addition to immunoglobulin heavy chain (IgH) and kappa light chain (Ig-K), one case had rearranged IgH and TCR-gamma chain but not Ig-K or TCR-beta, and two cases had only Ig-K rearrangement. One exceptional case in the B-cell lymphoma group had unrearranged, germline genotypes. In contrast, only 10 of 19 (53%) phenotypic T-cell lymphomas had rearranged TCR-beta, eight with concurrent TCR-gamma rearrangement. Of the remaining nine cases, six had germline configuration, two had rearranged Ig-K only, and one had both IgH and Ig-K rearrangement. This last case was reclassified as T-cell predominant, B-cell lymphoma. Thirteen of 16 cases of Hodgkin's disease had germline configuration; three cases had rearranged IgH and Ig-K, of which two were lymphocyte predominant with light chain monoclonality and one was a recurrence. Among 21 reactive lesions, 17 had germline configuration and four had rearranged IgH and Ig-K genes. Of these four cases, two were orbital lesions, one was a partially involved lymph node, and one developed a nodular lymphoma 9 months later. Our results indicate that almost all B-cell lymphomas have IgH and/or Ig-K rearrangement. In contrast, peripheral T-cell lymphomas have greater genotypic heterogeneity, and germline patterns for TCR genes are not uncommon. Reactive lesions and Hodgkin's disease tend to retain germline configuration, and any exception is often associated with an unusual clinical setting and/or histology. Genotypic analysis is thus most indicated in B-cell lymphomas with equivocal immunohistochemistry findings, T-cell lymphomas, and atypical cases of Hodgkin's disease and reactive lesions.

Comparison of transesophageal to transthoracic color Doppler echocardiography in the identification of intracardiac mycotic aneurysms in infective endocarditis

We report on cases of mycotic aneurysms in a group of 14 patients with infective endocarditis, all of whom were evaluated with transthoracic (TTE) and transesophageal (TEE) color Doppler echocardiography. Four mycotic aneurysms were found, one each in the left ventricular outflow tract, the right coronary sinus of Valsalva, the anterior mitral leaflet, and the atrial septum. With TTE, only three of four cases of mycotic aneurysms could be detected. Utilizing TEE, however, all were detected and their connections with the heart chambers or great vessels could be readily and clearly depicted, especially those in the atrial septum and mitral leaflet. We are of the opinion that TEE is superior to TTE in the identification and detailed analysis of mycotic aneurysms complicating infective endocarditis. In addition, we feel that echocardiography may help evaluate the progress of the disease, the location and direction of infection, and the extent of involvement of the mycotic aneurysms, providing useful information for guiding surgical intervention.

Preliminary observation of continuous albendazole therapy in alveolar echinococcosis

Fifteen cases of alveolar hydatid disease were treated with albendazole in the dosage of 20 mg/kg/d x 30 days for 12-60 courses. All cases were followed up 1-5 years (average 38 months) by ultrasonic scanning of liver and chest X-ray films. One patient whose hepatic lesion was converted into fibro-calcific after treatment was apparently cured. Twelve patients were symptomatically improved: jaundice (4 cases) and hemoptysis (2 cases) disappeared, with reduction in size of lesions in the liver and lung. Two patients in the late stage of disease with huge and extensive nodular masses in both lobes of the liver were not improved. Evidently, albendazole is effective in the treatment of alveolar hydatid disease. Early diagnosis and early treatment are to be emphasized.

Brain abscess in glycogen storage disease type Ib

Neutropenia, neutrophil dysfunction, and recurrent infections are important manifestations of glycogen storage disease type Ib. We report here a child who has had adequate metabolic control, but developed brain abscess, an infection not previously described in this disease. This case provides further evidence that the neutrophil anomaly is related to the basic enzyme defect, not secondary to the metabolic derangement.

DNA ploidy analysis of effectiveness of radiation therapy for cervical carcinoma

Cellular DNA content from 30 patients with cervical carcinoma was determined using flow cytometry before and after radiation therapy (RT). The authors attempted to correlate changes in DNA content, tumor response to RT, and post-RT pathologic findings. Before RT, tumors from eight of 30 patients (26.7%) were diploid or near-diploid; tumors from 22 patients (73.3%) were aneuploid. After RT, diploid or near-diploid tumors were found in 23 patients (76.7%), and aneuploid tumors were observed in seven patients (23.3%). Aneuploidy disappeared in 15 of the patient tumors, and complete tumor response (CR) was observed in 13 of these 15 patients (86.7%). Pathologic examinations were negative in 12 of 15 cases and suspicious in one of 15 cases. Of the seven patients whose tumor aneuploidy did not change after RT, CR was observed in only two (28.7%). Pathologic examinations were positive in five of seven cases and suspicious in one of seven cases. The CR for the 22 patients with pre-RT aneuploid tumors was 15 of 22 (68.2%); the CR for the eight patients with pre-RT diploid tumors was two of eight (25%, P less than 0.01). From these data the authors conclude there is a direct correlation between DNA content and radiosensitivity in cervical carcinoma. Aneuploid tumors from these patients were more radiosensitive than diploid tumors, and they patients had a better clinical tumor response and improved pathologic findings.

Adrenal autotransplantation with A-V anastomosis for treatment of Cushing's disease. A follow-up study of 31 cases

Thirty-one patients with Cushing's disease were treated with bilateral adrenalectomy and partial left adrenal autotransplantation with A-V anastomosis. They were followed up for 1 to 5 years. Three patients failed after adrenal autotransplantation to the abdominal muscle with the left gland's central vein anastomosed to the inferior epigastric artery. Twenty-eight patients underwent adrenal autotransplantation to the omentum with the gland's vein anastomosed to the gastroepiploic artery. Steroid could be omitted a short period after operation and life-long replacement therapy was avoidable in most patients. A few patients subsequently developed hypocorticalism. Two died and one had recurrence of Cushing's disease. Clinical and animal experimental results showed that the omentum is suitable for adrenal autotransplantation with A-V anastomosis. Transabdominal bilateral adrenalectomy and adrenal autotransplantation to the omentum with A-V anastomosis are acceptable in the treatment of Cushing's disease. The subsequent development of hypocorticalism and recurrence of Cushing's syndrome are also discussed.

Physical and genetic mapping of the CDR gene with particular reference to its position with respect to the FRAXA site

This study narrows down the localization of the gene coding for the cerebellar degeneration-related protein (CDR 34) to the upper boundary of the FRAXA and reports the finding of two common RFLPs respectively identified at an RsaI site flanking the 3' end of the gene and at a Hincll site flanking its 5' end. Segregation analysis carried out in the CEPH-pedigrees for the new CDR/RsaI-RFLP versus other polymorphic loci of the region has established a tight linkage with the markers DXS105/DX98 and absence of measurable linkage with two clusters of markers respectively located proximally to the FRAXA (F9, DXS102, DXS51, and DXS369) or distally to it (DXS52, DXS304). In addition, two recombinants were found among 23 scorable sibs identified in the Sardinian pedigrees segregating for the Martin-Bell Syndrome (MBS) and the CDR/RsaI variants. The overall evaluation of the in situ and genetic data reported suggest that the CDR locus 1) is located at the upper boundary of the FRAXA site; 2) is distal to DXS51 and proximal to DXS 389; and 3) segregates in a close linkage association with the loci DXS98 and DXS105 and, to a lesser extent, with the locus for MBS.

Type III glycogen storage disease: an adult case with mild disease but complete absence of debrancher protein

A 54-yr-old woman who presented with chest pain and elevated serum creatine kinase levels was found to have type III glycogen storage disease. Except for a history of hepatomegaly in childhood, she was healthy and lived a normal life. There was no hypoglycemia, seizure disorder or growth retardation. Muscle weakness was not apparent until the sixth decade. Despite the mild clinical course, debranching enzyme activity was not detectable by biochemical assay, and immunoblot analysis using a polyclonal antibody showed a complete absence of debrancher protein. Thus, mild clinical manifestations in this patient could not be explained by the residual debrancher enzyme and/or activity.

VATER and hydrocephalus: distinct syndrome?

VACTERL association with hydrocephalus is rarely reported, and is thought to be an autosomal recessive uniformly lethal disorder distinct from the VATER association. We have observed 3 patients in a 12-month period with hydrocephalus due to aqueductal stenosis, in addition to vertebral anomalies (3/3), anal anomalies (3/3), cardiac anomalies (3/3), tracheoesophageal fistula (1/3), renal anomalies (3/3), limb anomalies (3/3), single umbilical artery (2/3), hypospadias (1/3), and cryptorchidism (1/2). Chromosomes were normal in all cases. Although one patient died in the neonatal period due to respiratory failure, 2 have survived (30 months and 19 months) with good neurological outcome following early neurosurgical treatment. Although delayed in motor development, both are interactive, social, and continue to make developmental progress. Appropriate surgical treatment, including early ventriculoperitoneal shunting, allowed for the survival of 2 patients with an unexpectedly good outcome. Our experience suggests that the extremely poor prognosis previously ascribed is not universal. We caution against labeling this syndrome as a uniformly lethal, developmentally devastating disorder.

Type I glycogen storage disease: kidney involvement, pathogenesis and its treatment

Type I glycogen storage disease (GSD-I) is due to the deficiency of glucose-6-phosphatase activity in the liver, kidney and intestine. Although kidney enlargement occurs in GSD-I, renal disease has not been considered a major problem until recently. In older patients (more than 20 years of age) whose GSD-I disease has been ineffectively treated, virtually all have disturbed renal function, manifested by persistent proteinuria; many also have hypertension, renal stones, altered creatinine clearance or a progressive renal insufficiency. Glomerular hyperfiltration is seen in the early stage of the renal dysfunction and can occur before proteinuria. In younger GSD-I patients, the hyperfiltration is usually the only renal abnormality found; and, in some patients, microalbuminuria develops before clinical proteinuria. The predominant underlying renal pathology is focal segmental glomerulosclerosis. Renal stones and/or nephrocalcinosis are also common findings. Amyloidosis and Fanconi-like syndrome can occur, but rarely. The risk factors for developing the glomerulosclerosis in GSD-I include hyperfiltration, hypertension, hyperlipidemia and hyperuricemia. Dietary therapy with cornstarch and/or nasogastric infusion of glucose, aimed at maintaining normoglycemia, corrects metabolic abnormalities and improves the proximal renal tubular function. Long-term trial will be needed to assess whether the dietary therapy may prevent the evolution or the progression of the renal disease.

Hyperglycaemia associated with lactic acidaemia in a renal allograft recipient with type I glycogen storage disease

Renal disease is a frequent and serious complication of type I glycogen storage disease. A type I glycogen storage disease patient with focal segmental glomerulosclerosis and progressive renal insufficiency underwent a renal allograft transplantation. Despite the same cornstarch therapy, the post-transplantation course was complicated by worsening of the metabolic control manifested by exacerbated lactic acidaemia and hyperlipidaemia. This lactic acidaemia was remarkable for its association with hyperglycaemia. Hyperglycaemia accompanied by lactic acidaemia is strikingly unusual in type I glycogen storage disease, since this is a disease characterized by hypoglycaemia and an inverse relationship between blood glucose concentration and lactate levels. Both fasting insulin and C-peptide levels in the patient were greater than similar age-matched type I glycogen storage disease controls, indicating hyperinsulinaemia. The most likely mechanism responsible for the combined hyperglycaemia and lactic acidaemia was insulin resistance due to glucocorticoid treatment, instituted for immunosuppression. The hyperglycaemia associated with the lactic acidaemia was transient and resolved with steroid tapering. The exacerbated hyperlipidaemia, however, persisted after renal transplantation. Type I glycogen storage disease patients may be prone to glucocorticoid-induced insulin resistance, since the cellular metabolism in these patients may already be compromised with ineffective insulin action and/or reduced insulin output.

Spontaneous electromyographic potentials in chronic spinal cord injured patients: relation to spasticity and length of nerve

Nine patients with complete cervical spinal cord injury (SCI) had their vastus medialis, tibialis anterior, and gastrocnemius muscles evaluated with an electromyographic (EMG) examination in the acute (four to eight weeks) and chronic (more than one year) phases. The hypothesis that spontaneous EMG activity changes with time was assessed. During the chronic phase evaluation, a conduction study was performed to rule out peripheral nerve damage, and the amount of reflex activity was assessed on a scale of 0 to 5 (0 = areflexia; 5 = greater than 5 beats of clonus) to estimate the amount of spasticity. Subjects demonstrated normal conduction through the sensory (sural nerve) and/or motor segments of the peroneal and tibial nerves. In the acute phase, each muscle had spontaneous activity with no significant variation between different muscles of the same patient. In the chronic phase, there was a positive correlation between the degree of spontaneous activity in a muscle and the length of its axon (p less than .01) and a negative correlation between the amount of spontaneous activity and the degree of reflex activity (p less than .01). Specifically, the lower motor neuron in the chronic phase of an SCI seems to behave much like an axonopathy where the degree of spontaneous EMG activity is dependent on the length of the axon, with the additional concept that spontaneous activity is inhibited by spasticity.

Hemodynamic effects of hydralazine in mitral valve prolapse with regurgitation

Vasodilators cause the earlier occurrence of click and prolong the duration of regurgitation murmur in mitral valve prolapse (MVP), meanwhile, they also decrease the intensity of murmur. To investigate the net effects of vasodilators on mitral regurgitation (MR) caused by MVP, we studied the hemodynamic responses to intravenous hydralazine in 10 patients with MVP and associated MR. The results showed that hydralazine reduced systemic vascular resistance by 28% (1705 +/- 307 to 1223 +/- 227 dyne-sec-cm5 p less than 0.001) and produced a 30% increase in cardiac output (4.4 +/- 0.7 to 5.7 +/- 0.7 l/min, p less than 0.001). The forward stroke volume increased by 18% (56 +/- 12 to 66 +/- 11 ml, p less than 0.001), while regurgitant stroke volume fell by 14% (46 +/- 22 to 40 +/- 23 ml, p less than 0.05), with a resultant slight fall in pulmonary capillary wedge v wave (13 +/- 5 to 11 +/- 3 mmHg, p = 0.05). We thus suggest that hydralazine has beneficial hemodynamic effects on MVP with regurgitation, and may be effective in the treatment of these patients.

Definitive prenatal diagnosis for type III glycogen storage disease

Prenatal diagnosis for type III glycogen storage disease was performed by using (1) immunoblot analysis with a polyclonal antibody prepared against purified porcine-muscle debranching enzyme and (2) a qualitative assay for debranching-enzyme activity. Cultured amniotic fluid cells from three pregnancies (three families in which the proband had absence of debrancher protein) were subjected to immunoblot analysis. Two unaffected and one affected fetus were predicted. In addition, cultured amniotic fluid cells from nine pregnancies (eight families) were screened with a qualitative assay based on the persistence of a polysaccharide that has a structure approaching that of a phosphorylase limit dextrin when the cells were exposed to a glucose-free medium. This qualitative assay predicted six unaffected and three affected fetuses. All predictions by either method were confirmed postnatally except for one spontaneously aborted fetus. Our data indicate that a definitive diagnosis of type III glycogen storage disease can be made prenatally by these methods.

Induction of cytochrome P(1)450 RNA and benzo[a]pyrene metabolism in primary human hepatocyte cultures with benzanthracene

Exposure of cells to microsomal enzyme inducers can modify the potency of many carcinogens. We have examined the steady-state level of RNA from the P(1)450 gene and the metabolism of benzo[a]pyrene (BP) in primary cultures of human hepatocytes exposed for up to 4 days to 12.5 microM benzanthracene (BA), and in uninduced control cultures. While the steady-state levels of RNA from the P(1)450 gene were nondetectable in uninduced (DMSO only) human hepatocytes, 12.5 microM BA-induced AHH activity, BP metabolism, and/or P(1)450-specific RNA in hepatocytes from seven human cases were investigated. RNA levels specific for the P(1)450 gene appeared maximal at 24 hr following exposure to BA, whereas, the protein, as determined by AHH enzyme activity from BA-induced hepatocytes, continued to increase up to the last time point examined, 72 hr. BA induction for 96 hr increased metabolism of BP (initial concentration of BP, 10 microM) over a time course of 3, 6, 12, and 24 hr of incubation with BP compared with that of controls. The major metabolites of BP produced by human hepatocytes in culture were the unidentified polar BP metabolite(s), possibly polyhydroxylated. BA induction caused approximately a twofold increase in these metabolites. BA-induced cultures showed an increase in glutathione conjugation compared to that in controls. The percentage of glucuronide and sulfate conjugates remains similar in all cultures. Total binding of tritium label BP to DNA was 1.3-fold to fivefold greater in induced cultures, and related more to total metabolism than to production of a specific metabolite. Exposure of human hepatocytes in vitro to BA leads to a large increase in the steady-state level of the RNA specific for the P(1)450 gene and an increase metabolism of BP.

Aortic and pulmonary input impedance in patients with cor pulmonale

The hydraulic load of the right and left ventricles and the clinical effects of nifedipine were evaluated in 8 normal subjects (mean age: 55 years) and 8 patients with cor pulmonale secondary to chronic obstructive lung disease (mean age: 57 years). It was found that there were differences in the right ventricular resistance (174.62 +/- 25.96 vs 468.57 +/- 178.81 dyne/sec/cm-5), first zero crossing frequency (3.62 +/- 0.34 vs 6.07 +/- 3.56 Hz), steady power (218.95 +/- 32.25 vs 359.44 +/- 37.46 mW) and total power of right ventricle (275.81 +/- 36.18 vs 440.46 +/- 85.16 mW) between the normal and cor pulmonale patients, respectively. However, no significant changes in characteristic impedance, pulsatile power or aortic impedance were observed in the right pulmonary artery. After administration of nifedipine to patients with cor pulmonale, there were significant changes in resistance (468.57 +/- 178.81 vs 256.36 +/- 178.56 dyne/sec/cm-5), steady power (359.44 +/- 37.46 vs 225.51 +/- 114.64) and total power (440.46 +/- 85.16 vs. 289.27 +/- 50.85) of the pulmonary artery, respectively. Otherwise there were no significant changes in aortic input impedance or characteristic impedance of right pulmonary artery and pulsatile power. In conclusion, we found that: 1) the hydraulic vascular load in the right ventricle was higher in patients with cor pulmonale, 2) characteristic impedance that was not increased in cor pulmonale patients may be due to a dilated pulmonary artery, 3) there was no impedance mismatch between left ventricle and systemic arterial system in patients with cor pulmonale, and 4) by reducing the pulmonary vascular resistance through nifedipine administration, the total external right ventricular power might be reduced, without affecting the proximal pulmonary arterial compliance.