Up to 35% of patients with DCM may have an inherited disorder. Distinct clinical phenotypes can be observed in some families, suggesting a common molecular cause of the disease.

Reduced tolerance to high altitude may be associated with a low ventilatory and an increased pulmonary vascular response to hypoxia. We therefore, examined whether individuals susceptible to acute mountain sickness (AMS) or high altitude pulmonary oedema (HAPE) could be identified by noninvasive measurements of these parameters at low altitude. Ventilatory response to hypoxia (HVR) and hypercapnia (HCVR) at rest and during exercise, as well as hypoxic pulmonary vascular response (HPVR) at rest, were examined in 30 mountaineers whose susceptibility was known from previous identical exposures to high altitude. Isocapnic HVR expressed as difference in minute ventilation related to difference in arterial oxygen saturation (delta V'E/ delta Sa,O2) (L.min-1/%) was significantly lower in subjects susceptible to HAPE (mean +/- SEM 0.8 +/- 0.1; n = 10) compared to nonsusceptible controls (1.5 +/- 0.2; n = 10), but was not significantly different from subjects susceptible to AMS (1.2 +/- 0.2; n = 10). Hypercapnic ventilatory response was not significantly different between the three groups. Discrimination between groups could not be improved by measurements of HVR during exercise (50% maximum oxygen consumption (V'O2,max)), or by assessing ventilation and oxygen saturation during a 15 min steady-state exercise (35% V'O2,max) at fractional inspiratory oxygen (FI,O2) of 0.14. Pulmonary artery pressure (Ppa) estimated by Doppler measurements of tricuspid valve pressure at an FI,O2 of 0.21 and 0.12 (10 min) did not lead to a further discrimination between subjects susceptible to HAPE and AMS with the exception of three subjects susceptible to HAPE who showed an exaggerated HPVR. It is concluded that a low ventilatory response to hypoxia is associated with an increased risk for high altitude pulmonary oedema, whilst susceptibility to acute mountain sickness may be associated with a high or low ventilatory response to hypoxia. A reliable discrimination between subjects susceptible to high altitude pulmonary oedema and acute mountain sickness with a low ventilatory response to hypoxia is not possible by Doppler echocardiographic estimations of hypoxic pulmonary vascular response.

Real-time contrast-enhanced† sonography (RT-CES) can assess microvascular tissue perfusion using gasfilled microbubbles. The study was performed to evaluate the feasibility of RT-CES in detecting chronic allograft nephropathy (CAN) in comparison to color Doppler ultrasonography (CDUS). A total of 26 consecutive renal transplant recipients were prospectively studied using RT-CES and conventional CDUS. Transplant tissue perfusion imaging was performed by lowpower imaging during i.v. administration of the sonocontrast Optison TM . Renal tissue perfusion was assessed quantitatively using flash replenishment kinetics of microbubbles to estimate renal blood flow A * b (A = peak signal intensity, b = slope of signal intensity rise). In contrast to conventional CDUS resistance and pulsatility indices, renal blood flow estimated by CES was highly significant related to S-creatinine (r = -0.62, p = 0.0004). Determination of renal blood flow by CES reached a higher sensitivity (91% vs. 82%, p < 0.05), specificity (82% vs. 64%, p < 0.05) and accuracy (85% vs. 73%, p < 0.05) for the diagnosis of CAN as compared to conventional CDUS resistance indices. Perfusion parameters derived from RT-CES significantly improve the early detection of CAN compared to conventional CDUS. RT-CES using low-power real-time perfusion imaging is a feasible method to evaluate microvascular perfusion in renal allograft recipients.

The hydronephrotic rat kidney with intact circulation and innervation was split and spread out as a thin sheet in a tissue bath. The microvasculature was observed in vivo via television microscopy. We quantitated the effects of increasing concentrations (10(-9) to 10(-5) M) of saralasin (angiotensin II antagonist) applied locally in the tissue bath on microvascular diameters and on relative glomerular blood flow (measured using fluorescent labeled RBCs). Saralasin produced an increase in preglomerular diameters which was largest (37 +/- 11%) in the interlobular artery (there was no dilation in the afferent arteriole near the glomerulus), an increase in postglomerular diameters which was largest (17 +/- 4%) in the efferent arteriole near the glomerulus, and an increase in blood flow (19 +/- 4%). If these types of findings would hold for the normal kidney, it would suggest a role for angiotensin II in the control of total renal blood flow, in the regional distribution of flow, and in the control of filtration fraction. We also made control micropressure measurements using the servo-nulling approach. Pressures measured were: afferent arteriole, 65 +/- 5 mm Hg; intraglomerulus, 50 +/- 5 mm Hg; and efferent arteriole, 19 +/- 3 mm Hg. These data indicate that there is major vascular resistance near the glomerulus, especially in the efferent arteriole.