Effects of Blood Flow Restriction on O2 Muscle Extraction and O2 Pulmonary Uptake Kinetics During Heavy Exercise

This study aimed to determine the effects of three levels of blood flow restriction (BFR) on V˙O2 and O2 extraction kinetics during heavy cycling exercise transitions. Twelve healthy trained males completed two bouts of 10 min heavy intensity exercise without BFR (CON), with 40% or 50% BFR (BFR40 and BFR50, respectively). V˙O2 and tissue saturation index (TSI) were continuously measured and modelled using multiexponential functions. The time constant of the V˙O2 primary phase was significantly slowed in BFR40 (26.4 ± 2.0s; p < 0.001) and BFR50 (27.1 ± 2.1s; p = 0.001) compared to CON (19.0 ± 1.1s). The amplitude of the V˙O2 slow component was significantly increased (p < 0.001) with BFR in a pressure-dependent manner 3.6 ± 0.7, 6.7 ± 0.9 and 9.7 ± 1.0 ml·min−1·kg−1 for CON, BFR40, and BFR50, respectively. While no acceleration of the primary component of the TSI kinetics was observed, there was an increase (p < 0.001) of the phase 3 amplitude with BFR (CON −0.8 ± 0.3% VS BFR40 −2.9 ± 0.9%, CON VS BFR50 −2.8 ± 0.8%). It may be speculated that BFR applied during cycling exercise in the heavy intensity domain shifted the working muscles to an O2 dependent situation. The acceleration of the extraction kinetics could have reached a plateau, hence not permitting compensation for the slowdown of the blood flow kinetics, and slowing V˙O2 kinetics.

Semi-quantification of Myocardial Uptake of Bone-seeking Agents in Suspected Cardiac Amyloidosis

Introduction:In recent years, bone scintigraphy has emerged as a key tool for non-invasive etiologic diagnosis of transthyretin (ATTR) cardiac amyloidosis (CA). The qualitative Perugini scoring system is currently the most widely-used method to evaluate myocardial uptake of bone-seeking agents. A semi-quantitative approach may, however, be more useful in clinical practice for both diagnosis and therapeutic follow-up. In this study we focused on a new semi-quantification method with the aim of improving the diagnostic accuracy of CA. Material and Methods:We retrospectively evaluated 8674 consecutive 99mTc-biphosphonate (HMDP or DPD) scintigraphies performed at the Nuclear Medicine Unit of the Azienda Ospedale-Università Padova between January 2012 and December 2016. The qualitative Perugini scoring system was compared with three recently proposed semi-quantitative indices (ratio of heart to thighs: RHT; ratio of lungs to thighs: RLT; ratio of femur to thighs: RFT) in 68 individuals presenting significant myocardial uptake (mean age 79 ± 7 years, range 62-100 years; female/male ratio 16/52). We took 349 consecutive bone scintigraphies qualitatively absent of any cardiac/pulmonary uptake as healthy controls (HC).Results:The RHT and RLT indices (for both males and females) were significantly higher in patients (visual Perugini scores from 1 to 3) than in HCs (p £0.0001). There were also statistically significant differences for RHT (in both sexes) in HCs vs patients with qualitative scores of 1 or >1 (with p ranging from £0.001 to £0.0001). Analysis of the ROC curves showed that RHT outperformed the other two indices (RLT and RFT) and was more sensitive and specific in both male and female groups. Furthermore, in the male population, RHT very accurately distinguished HCs and patients with scores of 1 (known to be less likely affected by ATTR) from patients with qualitative scores >1 (known to be more likely affected by ATTR) with an AUC of 99% (sensitivity: 95%; specificity: 97%).Conclusion:The proposed semi-quantitative RHT index can accurately distinguish between HCs and subjects with CA (Perugini scores from 1 to 3) in both females and males. Furthermore, RHT is able to predict with very high accuracy subjects in the male population more likely to be affected by ATTR (qualitative scores >1).

An unusual cause of pulmonary calcification

Metastatic pulmonary calcification (MPC) is an uncommon entity resulting from abnormalities in calcium-phosphorus homoeostasis. Most cases reported in the literature are among patients with chronic kidney disease receiving haemodialysis. Primary hyperparathyroidism is a relatively common condition affecting calcium homoeostasis, in which MPC can rarely occur. We report the case of one such patient who presented with severe hypercalcaemia and features of interstitial lung disease. Radiographic imaging was normal and the diagnosis was clinched by diffuse pulmonary uptake in 99mTechnetium-methylene diphosphate scan.