Use of the photoplethysmographic technique to analyze the Valsalva maneuver in normal man.

We analyzed the Valsalva maneuver (VM) using a photoplethysmographic technique in 24 normal subjects. We studied the effects of test duration (range 5 to 20 seconds) and magnitude of expiratory pressure (EP, range 20 to 50 mmHg) on maximal (% delta) and time integrated (int) changes in heart rate (HR), and mean (MAP) and pulse (PP) pressures during phases II and IV. At all EPs, there was correlation (P less than 0.01) between % delta MAP in both late phase II and phase IV and duration of the VM. The Valsalva ratio (VR) correlated with test duration only at high EPs. All responses, except the fall in MAP in early phase II and bradycardia in phase IV, correlated with EPs. The VR correlate not only with HR responses in phases II and IV but also with MAP and PP overshoot in phase IV. Correlations between maximal AP and HR changes in either phase II and IV were poor. Our study indicates that the photoplethysmographic technique allows a more rational interpretation of the VM in the clinical setting. The VR cannot be adequately interpreted without comcomitant monitoring of arterial pressure during the VM.     

应用数学模式对高血压脉图进行血流动力学有关参数分析

通过脉图的多种特征性参数与临床实测的心血管参数之间进行统计处理,建立数学模式及计算机程序。对50例高血压病进行检验比较,得出脉图图象分析与实测结果之间的平均误差为10～20%,说明从桡动脉压力脉搏图来分析心血管参数是具有一定的参考价值。     

Acute Gastric Lesions Induced by Transcatheter Arterial Embolization and Intra-arterial Infusion Chemotherapy for Hepatocellular Carcinoma

We performed an endoscopic study of the acute gastric lesions induced by transcatheter arterial embolization (TAE) and infusion chemotherapy (one shot infusion: OSI). Forty-eight patients with primary hepatocellular carcinoma were investigated, and of them, 25 received TAE and 23 were treated with OSI. Endoscopy was performed within 1 week both before and after therapy and any gastric mucosal changes were noted. Before treatment, all patients had gastric lesions such as redness, erosion, hemorrhage and ulcer. These lesions were exacerbated or new lesions appeared after both TAE and OSI in about 50% of the subjects, and no significant difference in the incidence of lesions was observed between these two treatments. Moreover, there was no significant correlation between the exacerbation or new appearance of gastric lesions and the Child's classification, the catheter position, or the presence or absence of A-P shunt or portal thrombus. The appearance and/or exacerbation of these gastric lesions was not prevented by the administration of common antiulcer drugs before treatment. Thus the possibility that these gastric effects of TAE and OSI may occur should always be kept in mind and appropriate preventive or therapeutic measures should be adopted.     

降纤酶治疗视网膜动脉阻塞的临床研究

目的观察降纤酶治疗视网膜动脉阻塞的疗效及血液流变学变化。方法视网膜动脉阻塞患者49例，分为2组：治疗组25例，应用降纤酶治疗；对照组24例，应用低分子右旋糖酐治疗；其它治疗方法相同。2组治疗前后均分别检查视力及眼底变化以判断疗效，同时检查血液流变学变化。结果治疗组显效率为72．0％，总有效率为88．0％，对照组显效率为20．8％，总有效率为58．3％，2组相比有显著差异（P〈0．01，P〈0．05）。治疗组治疗后纤维蛋白原、血浆黏度、全血黏度下降明显，与治疗前及对照组相比差异显著（P〈0．01，P〈0．05）。结论降纤酶能改善血液流变，降低纤维蛋白原，改善血液循环，治疗视网膜动脉阻塞的疗效显著。     

ARTERIAL AND VENOUS EFFECTS OF VERAPAMIL IN NORMAL VOLUNTEERS

1. The effects of verapamil (120 mg orally) and a placebo on arterial pressure, heart rate, PR interval, arterial flows and diameters of the brachial and carotid arteries (pulsed Doppler technique), forearm vascular resistance, and venous diameter and compliance (cutaneous microstrain gauge and plethysmography) have been compared over a 10-hr period in six healthy volunteers during a double-blind and cross-over study. 2. Verapamil reduced diastolic blood pressure by approximately 10 mm Hg, did not affect heart rate and increased PR interval by approximately 15%. 3. Verapamil significantly increased brachial and carotid arterial blood flows by 56% (P less than 0.01) and 16% (P less than 0.05), respectively, but the diameters of these vessels were not significantly modified (+7 and +4%, respectively, NS). Forearm vascular resistance decreased by 40% (P less than 0.01), indicating that verapamil preferentially dilates small arteries. All these effects peaked at 2 h after drug intake and lasted for 6 h. 4. Verapamil increased hand dorsal vein diameter and flow by 95% (P less than 0.05) and 80% (P less than 0.05), respectively, from 2 to 4 h after drug intake but venous compliance, assessed by the venous diameter/venous flow ratio, was not significantly modified (from 0.71 to 0.69, NS), thus indicating that veins are not directly affected by this drug.     

Comparison of hypercapnia‐based calibration techniques for measurement of cerebral oxygen metabolism with MRI

MRI may be used to measure fractional changes in cerebral oxygen metabolism via a metabolic model. One step commonly used in this measurement is calibration with image data acquired during hypercapnia, which is a state of increased CO₂ content of the blood. In this study some commonly used hypercapnia‐inducing stimuli were compared to assess their suitability for the calibration step. The following stimuli were investigated: (a) inspiration of a mixture of 4% CO₂, 21% O₂ and balance N₂; (b) 30‐s breath holding; and (c) inspiration of a mixture of 4% CO₂ and 96% O₂ (i.e., carbogen). Measurements of BOLD and cerebral blood flow made on nine subjects during the different hypercapnia‐inducing stimuli showed that each stimulus leads to a different calibration of the model. We argue that of the aforementioned stimuli, inspiration of 4% CO₂, 21% O₂ and balance N₂ should be preferred for the calibration as the other stimuli produce responses that violate assumptions of the metabolic model. Magn Reson Med 61:391–398, 2009. © 2009 Wiley‐Liss, Inc.     

Severe spontaneous arterial thrombotic manifestations in patients with inherited hypo- and afibrinogenemia

Summary.  We report two novel cases of severe arterial thrombotic episodes occurring in two women with severe hypofibrinogenemia, not linked to the administration of replacement therapy. The first patient had sudden acute occlusion of the anterior branch of left renal artery with infarction of the antero-lateral region of the upper part of the left kidney during treatment with combined oestrogen-progestogen started 16 years before for recurrent haemoperitoneum caused by bleeding at ovulation. The second patient showed recurrent arterial thrombosis of lower limbs over 2 years, which eventually led to amputation of affected limbs. Thrombotic events in patients with inherited severe hypofibrinogenemia are rather frequent, may be severe and not associated with the use of replacement therapy.     

Abnormal pressure–natriuresis in hypertension: role of nitric oxide

The kidneys have a critical role in long‐term control of arterial pressure by regulating extracellular fluid and plasma volume. According to the renal body fluid feedback mechanism for long‐term control, persistent hypertension can only occur as a result of a reduction in renal sodium excretory function or a hypertensive shift in the pressure–natriuresis relationship. Although an abnormal relationship between renal perfusion pressure and renal sodium excretion has been identified in every type of hypertension where it has been sought, factors responsible for this effect are still unclear. Nitric oxide (NO) is produced within the kidney and plays an important role in the control of many intrarenal processes which regulate the renal response to changes in perfusion pressure and thus, help determine plasma volume and blood pressure. Numerous studies have shown that long‐term inhibition of NO synthesis results in a chronic rightward shift and marked attenuation in renal pressure–natriuresis. Recent studies have shown that certain animal models of genetic hypertension and forms of human hypertension areas are associated with a decrease in NO synthesis. Reductions in NO synthesis reduces renal sodium excretory function not only through direct actions on the renal vasculature, but through modulation of other vasoconstrictor processes and through direct and indirect alterations in tubular sodium transport. The causes and consequences of the dysregulation of NO in hypertension and other renal disease processes remain an important area of investigation.     

High-sensitivity single-shot perfusion-weighted fMRI.

A method is presented for measurement of perfusion changes during brain activation using a single-shot pulsed spin labeling technique. By employing a double-inversion labeling strategy, stationary tissue (background) signal was suppressed while minimally affecting perfusion sensitivity. This allowed omission of the otherwise required reference scan, resulting in twofold-improved temporal resolution. The method was applied to visual and motor cortex activation studies in humans, and compared to standard FAIR-type perfusion labeling techniques. Experiments performed at 1.5T and 3.0T indicate a close to 90% suppression of background signal, at a cost of an 11% and 9%, respectively, reduction in perfusion signal. Combined with the twofold increase in signal averaging, and a reduction in background signal fluctuations, this resulted in a 64% (1.5T, N = 3) and a 128% (3T, N = 4) overall improvement in sensitivity for the detection of activation-related perfusion changes. Magn Reson Med 46:88-94, 2001. Published 2001 Wiley-Liss, Inc.