Objective To determine whether Libman-Sacks endocarditis is a pathogenic factor for cerebrovascular disease (CVD) in systemic lupus erythematosus (SLE). Background A cardioembolic pathogenesis of SLE CVD manifested as 1) neuropsychiatric SLE (NPSLE) including stroke and transient ischemic attacks (TIA), 2) neurocognitive dysfunction, and 3) MRI focal brain lesions has not been established. Methods A 6-year study of 30 patients with acute NPSLE (27 women, age 38±12 years), 46 age-and-sex matched SLE controls without NPSLE (42 women, age 36±12 years), and 26 age-and-sex matched healthy controls (22 women, age 34±11 years) who underwent clinical and laboratory evaluations, TEE, carotid duplex, transcranial Doppler, neurocognitive testing, and brain MRI/MRA. NPSLE patients were re-evaluated after 4.5 months of therapy. All patients were followed clinically for a median of 52 months. Results Libman-Sacks vegetations (87%), cerebromicroembolism (27% with 2.5 times more events per hour), neurocognitive dysfunction (60%), and cerebral infarcts (47%) were more common in NPSLE than in SLE (28%, 20%, 33%, and 0%) and healthy controls (8%, 0%, 4%, and 0%, respectively) (all p≤0.009). Patients with vegetations had 3 times more cerebromicroemboli per hour, lower cerebral blood flow, more stroke/TIA and overall NPSLE events, neurocognitive dysfunction, cerebral infarcts, and brain lesion load than those without (all p≤0.01). Libman-Sacks vegetations were independent risk factors of NPSLE (OR=13.4, p<0.001), neurocognitive dysfunction (OR=8.0, p=0.01), brain lesions (OR=5.6, p=0.004), and all 3 outcomes combined (OR=7.5, p<0.001). Follow-up re-evaluations in 18 (78%) of 23 surviving NPSLE patients demonstrated improvement of vegetations, microembolism, brain perfusion, neurocognitive dysfunction, and lesion load (all p≤0.04). Finally, patients with vegetations had reduced event free survival time to stroke/TIA, cognitive disability, or death (p=0.007). Conclusion The presence of Libman-Sacks endocarditis in patients with SLE is associated with higher risk for embolic CVD. This suggests that Libman-Sacks endocarditis may be a source of cerebral emboli.

We tested the hypotheses that Doppler echocardiography has a higher accuracy than clinical evaluation in the detection of significant aortic and mitral valvular heart disease and that Doppler echocardiography is highly accurate as compared with cardiac catheterization for the assessment of valvular disease severity.

Some animals have adapted to hypoxia by increasing their haemoglobin affinity for oxygen, but in vitro studies have not shown any change of haemoglobin affinity for oxygen in human high altitude natives or lowlanders acutely acclimatized to high altitude. We conducted the first in vivo study of the oxyhaemoglobin dissociation curve by progressively reducing arterial PO 2 while maintaining normocapnia in lowlanders at sea level, lowlanders sojourning at 3600m for two weeks and native Andeans at the same altitude. We found that the in vivo PO 2 at which haemoglobin is half-saturated (P 50 ) is higher in lowlanders at sea level (32 mmHg) than that measured in vitro (27 mmHg) and that lowlanders and highlanders do significantly increase the in vivo affinity of their haemoglobin for oxygen with exposure to high altitude. These results indicate the value of an in vivo approach for studying the oxyhaemoglobin dissociation curve.iii

High altitude pulmonary edema is characterized hemodynamically by a markedly restricted pulmonary vascular bed. Pulmonary vascular resistance is six to eight times higher than control values at altitude, and mean pulmonary pressure is generally elevated two to four-fold over control values. We wished to compare the effect of various vasodilators on the hemodynamics of HAPE, both to gauge their potential effectiveness in treatment of HAPE, and also to gain clues as to the mechanism of the altered pulmonary circulation. In a series of field experiments using a total of 16 subjects with HAPE and 10 well controls, we measured pulmonary hemodynamics by non-invasive Doppler echocardiography. The per cent reduction in pulmonary vascular resistance and mean pulmonary artery pressure, respectively, were 46 and 33 for oxygen, 30 and 29 for nifedipine, 29 and 25 with hydralazine, 57 and 42 with phentolamine, and 72 and 52 when oxygen and phentolamine were combined. All the vasodilators improved gas exchange, suggesting a link between edema formation and pulmonary vasoconstriction. A number of vasodilators may be useful in the treatment of HAPE; the superiority of an alpha adrenergic blocker may implicate the sympathetic nervous system in the pathophysiology of high altitude pulmonary edema.

A 3.0 MHz pulsed Doppler echocardiography was used to estimate instantaneous stroke volume (SV) and cardiac output (Q) in eight men during steady-state supine (S) and upright (U) exercise at 300 kpm/min. The mean transients in heart rate (HR), SV, and Q for the first 20 s of exercise in each posture were then determined. Center-line blood velocities were obtained in the ascending aorta with the transducer positioned manually in the suprasternal notch. Mean supine values for SV and Q at rest and exercise were 111 ml and 6.4 1/min and 112 ml and 9.71/min, respectively. The corresponding results for U were 76 ml and 5.61/min and 92 ml and 8.41/min, respectively. These values compare favorably with previous studies utilizing invasive procedures. The transient response of Q following the onset of exercise in U was about twice as fast as in S because of the rapid and almost immediate upsurge in SV. In S, only HR served to augment Q, as SV initially fell. The faster rise in aortic flow in U with exercise represented an additional volume (184 ml) of blood passing through the aorta compared with S in the first 20s. This must be related to the rapid mobilization of pooled venous blood from the leg veins during U.