Is the standard weight-based dosing of dobutamine for stress testing appropriate for patients of widely varying body mass index?

Although a gradual increase in heart rate (HR) during dobutamine stress testing (DST) is desired, few data exists regarding whether this is similarly achieved in patients of widely varying body mass index (BMI). Whether difference in BMI contributes to variation in the hemodynamic and symptomatic response to dobutamine is also unknown

Identification of a Locus for Autosomal Dominant Polycystic Liver Disease, on Chromosome 19p13.2-13.1

Polycystic liver disease (PCLD) is characterized by the growth of fluid-filled cysts of biliary epithelial origin in the liver. Although the disease is often asymptomatic, it can, when severe, lead to complications requiring surgical therapy. PCLD is most often associated with autosomal dominant polycystic kidney disease (ADPKD); however, families with an isolated polycystic liver phenotype without kidney involvement have been described. The clinical presentation and histological features of polycystic liver disease in the presence or absence of ADPKD are indistinguishable, raising the possibility that the pathogenetic mechanisms in the diseases are interrelated. We ascertained two large families with polycystic liver disease without kidney cysts and performed a genomewide scan for genetic linkage. A causative gene, PCLD, was mapped to chromosome 19p13.2-13.1, with a maximum LOD score of 10.3. Haplotype analysis refined the PCLD interval to 12.5 cM flanked by D19S586/D19S583 and D19S593/D19S579. The discovery of genetic linkage will facilitate diagnosis and study of this underdiagnosed disease entity. Identification of PCLD will be instrumental to an understanding of the pathogenesis of cyst formation in the liver in isolated PCLD and in ADPKD

Exercise-Echocardiography-Derived Pulmonary Artery Pressure Slope in Borderline and Mild to Moderate Pulmonary Arterial Hypertension

Objective Examine pulmonary artery systolic pressure (PASP) response to exercise in isolated borderline and mild to moderate pulmonary arterial hypertension (PAH). Methods Doppler stress echocardiography was performed in 32 healthy volunteers with resting PASP of 29 mm Hg or less, 39 with resting PASP between 30 and 40 mm Hg, and 7 with resting PASP between 41 and less than 60 mm Hg. All subjects had otherwise normal echocardiograms. Results Rate of increase in PASP with exercise was positively associated with resting PASP ( P < 0.001), increased age ( P < 0.001), and estrogen use among women ( P = 0.001). On multivariate analysis, PASP slope was independently related ( P = 0.03) to resting PASP and inversely associated with exercise time ( P < 0.001). Conclusions Patients with borderline and mild to moderate resting PAH have an exaggerated PASP response to exercise. PASP slope is a strong independent predictor of exercise time. Outcome studies are needed to determine the prognostic significance of this finding