Diving physiology and pathophysiology

Summary. Divers have worked at 500 m depth in the sea and have reached 700 m in simulated chamber dives. A prerequisite for this has been extensive physiological studies of the body's reactions to pressure and pressure changes. This paper reviews such physiological and pathophysiological studies with emphasis on recent developments.     

The Significance of Anatomical Variations of Hepatic Artery and Multiple Arterial Supplies in Embolization of Liver Tumors

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Hepatic falciform artery

The hepatic falciform artery is an occasional terminal branch of the left or middle hepatic artery, and may provide an uncommon but important collateral route when the principal visceral arteries are occluded.     

Whole-brain 3D perfusion MRI at 3.0 T using CASL with a separate labeling coil.

A variety of continuous and pulsed arterial spin labeling (ASL) perfusion MRI techniques have been demonstrated in recent years. One of the reasons these methods are still not routinely used is the limited extent of the imaging region. Of the ASL methods proposed to date, continuous ASL (CASL) with a separate labeling coil is particularly attractive for whole-brain studies at high fields. This approach can provide an increased signal-to-noise ratio (SNR) in perfusion images because there are no magnetization transfer (MT) effects, and lessen concerns regarding RF power deposition at high field because it uses a local labeling coil. In this work, we demonstrate CASL whole-brain quantitative perfusion imaging at 3.0 T using a combination of strategies: 3D volume acquisition, background tissue signal suppression, and a separate labeling coil. The results show that this approach can be used to acquire perfusion images in all brain regions with good sensitivity. Further, it is shown that the method can be performed safely on humans without exceeding the current RF power deposition limits. The current method can be extended to higher fields, and further improved by the use of multiple receiver coils and parallel imaging techniques to reduce scan time or provide increased resolution.     

Removing the effect of SVD algorithmic artifacts present in quantitative MR perfusion studies.

Quantitative cerebral blood flow (CBF) values can be obtained from dynamic susceptibility contrast (DSC) MR perfusion studies using the standard singular value decomposition (sSVD) deconvolution algorithm. Reports in the literature from simulation and in vivo studies suggest that CBF estimates obtained using sSVD deconvolution depend on the arterial-tissue delay (ATD). By contrast, Fourier transform (FT) deconvolution produces CBF estimates that are independent of ATD. The diagnostic reliability of quantitative CBF measurements to define areas of normal tissue flow and tissue at risk is brought into doubt by such gross sensitivity to the specifics of the deconvolution approach. This variation of CBF values with ATD is shown to be an artifact associated with the current implementation of the sSVD deconvolution algorithm. A reformulated version of the SVD deconvolution algorithm (rSVD) is presented and compared to the standard SVD algorithm through simulation and patient case studies.     

腓动脉皮支逆行岛状皮瓣的解剖与应用改进

目的探讨腓动脉皮支逆行岛状皮瓣的解剖学基础及临床应用效果。方法采用新鲜及防腐尸体下肢共25肢,对腓动脉皮支进行解剖学观测。于2003年9月~2005年6月收治足跖趾关节处软组织缺损患者10例,男8例,女2例。年龄21~55岁。其中背侧6例,跖侧4例,缺损范围10cm×6cm~15cm×10cm。应用带有外踝上11.0±1.7cm腓动脉固定皮支的腓动脉皮支逆行岛状皮瓣修复,皮瓣范围11.0cm×6.5cm~16.0cm×11.0cm。供区6例直接减张缝合,4例行自体游离皮片覆盖。结果解剖学观测外踝上11.0±1.7cm自腓动脉发出一固定皮支,起始点直径1.45±0.12mm,入深筋膜点距腓肠神经营养血管皮瓣轴线15.70±1.20mm。10例患者术后皮瓣均成活,血运良好,无静脉回流障碍;供区愈合良好。术后获随访6~12个月,皮瓣外形良好,质地、色泽与周边相似,足功能恢复良好,两点辨别觉11~18mm。结论腓动脉皮支逆行岛状皮瓣经改进后血运好,逆转距离长,修复范围大,操作简便,为临床修复足中远端软组织缺损提供了一种新方法。     

Amputation in elderly and high-risk vascular patients

Fifty-eight patients underwent lower limb amputation for arterial disease over a 30-month period. Mean age of the patients was 72 years. Cardiopulmonary and metabolic risk factors were present in the majority of the patients. Postoperative one-year and three-year mortality rates were 24, 40, and 76%, respectively. Contralateral amputation was required in one-third of the patients after a mean period of eight months. Only younger and healthier patients returned to a meaningful social life after appropriate prosthetic fitting. In view of the high mortality and morbidity rates, above-knee amputation seems a better choice than below-knee amputation in these elderly and high-risk patients.     

动脉韧带与左喉返神经的解剖研究

本文用30例成人尸体观察了动脉韧带和左喉返神经,动脉韧带长1.2.97±4.53mm,圆索状动脉韧带23例(77％),直径为3.92±1.12mm。动脉韧带的主动脉端附着于主动脉弓(80％)或降主动脉(20％),肺动脉端附着于左肺动脉,6例肺动脉端位于心包内。19例(63％)左喉返神经绕主动脉弓,11例(37％)绕动脉韧带的主动脉端。     

Blood pressure reduction in pregnancy by sodium chloride.

Volume expansion in the presence of elevated aldosterone availabilityis a hallmark of normal pregnancy. Intravascular volume depletioncharacterizes severe pregnancy-associated disease conditionssuch as intra-uterine growth retardation, chronic hypertensionor pre-eclampsia [1]. Two hypotheses have been forwarded toexplain volume depletion in pregnancy: the first hypothesischarges inappropriate sensing of vascular ‘overfilling’,resulting in an increased transendothelial loss of fluid tothe extravascular compartment. In contrast, the second hypothesisfocuses on vascular ‘underfilling’ due to inappropriatelylow aldosterone levels. The second hypothesis is based on theassumption that a compensatory increase in the circulating fluidvolume is required in normal pregnancy to support fetal substratedelivery. According to the second concept, maternal blood pressureincreases due to counter-regulatory mechanisms when placentalblood supply is reduced [2]. In support of the ‘underfilling’hypothesis are observations that a     

Ankle-brachial index and extent of atherothrombosis in 8891 patients with or at risk of vascular disease: results of the international AGATHA study.

AIMS: AGATHA (a Global Atherothrombosis Assessment) was designed to assess the extent of atherothrombosis and the use of the ankle-brachial index (ABI) in vascular patients. The principal hypotheses were that (1) in diseased patients, a low ABI was related to the number and site of vascular beds affected and (2) in at-risk patients without disease, a low ABI was related to the number of risk factors present. METHODS AND RESULTS: Patients were recruited consecutively by 482 clinicians in 24 countries and the ABI measurement was performed at a single visit. Of 8891 patients recruited, 1792 were defined as at risk and 7099 as with disease. Of the with-disease patients, 65.2% had one arterial bed affected, 27.6% two and 7.1% all three. Abnormal ABI (< or =0.9) was present in 30.9% of at-risk and 40.5% of with-disease patients. A lower ABI was weakly associated with an increasing number of risk factors in at-risk patients (r=-0.056, P=0.02) and with the site and number of arterial beds affected in with-disease patients (P<0.001). CONCLUSION: This large international study confirms that atherothrombotic disease often occurs at more than one site. The ABI is related to the risk factor profile and to the site and extent of atherothrombosis.