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Arteriovenous Malformation 动静脉畸形

发表于 3-26-2018 12:35:53 | 显示全部楼层 |阅读模式
本帖最后由 choi 于 3-27-2018 14:45 编辑

Lisa Sanders, Teenage Nightmare. A young woman's heart stopped and blood was pouring from her nose. What was going on? New York Times Magazine, Mar 18, 2018.
https://www.nytimes.com/2018/03/ ... so-excessively.html

My comment:
(a) Despite the suspense of this essay, diagnosis should have been straightford.I will discuss two curiosities in the essay.
(i) "The friend rolled the girl onto her side [if a patient is supine and unconscious, she might breathe in blood and caused suffocation; by definition of unconsciousness, she could not swallow], and an enormous amount of dark red blood gushed out onto the carpet."
* "The gag reflex involves a brisk and brief elevation of the soft palate and bilateral contraction of pharyngeal muscles evoked by touching the posterior pharyngeal wall."  en.wikipedia.org.
* "The gag reflex is a protective response that prevents foreign objects or noxious material from entering the pharynx, larynx, or trachea; it is not elicited during a normal swallow."
* Gag reflex may or may not be absent in an unconscious patients, depending levels of unconsciousness was well as whether the reflex arc (sensory nerve or motor nerve accounting for the reflex) is damaged (by a stroke or trauma)/
(B) Theoretically the blood should be arterial (color: bright red) in nature, not venous (dark red) -- simply because a hole in AVM (see the following) will release arterial blood, whose pressure is higher than venous blood. I search the Web as well as medical reports), and find a rare report about color of hemoptysis.

Dar MY et al, Pulmonary Arterio-Venous Malformation (PVAM) Presenting as Recurrent Hemoptysis. Journal of Medical Science and Clinical Research (JMSCR), 5: 27862-27867 (2017; under the heading "Case report")
("17 Years male farmer presented with chief complaints of coughing of blood (hemoptysis) 1 year.  It was insidious in onset, paroxysmal, bright red in color, around half a tea spoon (approx 2.5 ml) in amount in each episode with frequency of around 1-2 episodes per day and repeated episodes with normal intervals of weeks to months")

Because the authors, Indians of India, are not native speakers of English, the English in this report has room for improvement.
(C) medical terms (pay attention to etymologies and pronunciations; both shown here are American spellings):
* hemoptysis 咳血/咯血
* hematemesis 吐血

It is hard to believe this patient could not differentiate the two. Sure, she was unconscious in the reported episode. However, AVM is typified by many leaks prior to a disastrously heavy and sudden bleeding (as here, where the patient had not anticipate da cardiac arrest, and warned against calling an ambulance). The cause of cardiac arrest? The essay did not estimate how much blood she lost. Could it be hypovolemic shock 低血容 [积] 性休克?

If the patient has known and told doctors that she coughed, not vomited, blood, she did not need gastroscopy 胃镜 (which examines esophagus 食道 and stomach, but not small intestine, whose diameter is small).
(ii) Before CT (standing for computed tomography) scan, physical examination of the patient should have disclosed bruit (see (e)(i) below) over the affected lung.
(A) tome (n; Did You Know?)
(B) physical examination (in China: 体格检查): "是指医师运用自己的感官和借助于传统或简便的检查工具,如体温表、血压计、叩诊锤、听诊器、检眼镜等,来客观地了解和评估病人身体状况的一系列最基本的检查方法。"  中国医科大学附属第一医院, undated.
AVM in a lung looks like a mass in plain chest-X-ray and CT scan without contrast medium. See Figure 1 (a) and (b), respectively, in
(iii) Claire L Shovlin, Pulmonary Arteriovenous Malformations. American journal of respiratory and critical care medicine, 190: 1217–1228 (2014)

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 楼主| 发表于 3-26-2018 12:37:53 | 显示全部楼层
本帖最后由 choi 于 3-26-2018 13:45 编辑

(b) I will talk about two other points in this essay.
(i) The patient had an episode "around Chjavascript:;ristmas," whose laboratory tests shows elevated troponin, despite normal heart rhythm (beats) and echocardiogram. Am Fam Physician. 72: 119-126 (2005)

This is hardly mysterious. See Achar SA et al, Diagnosis of Acute Coronary Syndrome. American Family Physician, 72: 119-126 (2005)
("Troponin T or I generally is the most sensitive determinant of acute coronary syndrome, although the MB isoenzyme of creatine kinase also is used. * * * A normal electrocardiogram does not rule out acute coronary syndrome")

In humans, troponin is only found in skeletal or cardiac muscles but not smooth muscle. Generally speaking, when a cell dies, the disintegration of the cell leads to release into blood stream of its innards. There are three isoforms of troponin: C, I and T. Troponin I and  T will both elevate in acute and chronic heart conditions.
(ii) Hereditary hemorrhagic telangiectasia (HHT) is not much known beyond AVM. Wait until you read (f).

(c) To do a CT scan, the patient "would have one more needle stick (for the contrast dye) * * * Dr Tej Phatak [at Newark Beth Israel Medical Center] was both a pediatrician and the radiologist helping to manage her care. Through the control-room window, he saw the girl’s tear-streaked face disappear into the scanner, then watched the pictures click into place on his monitor. Suddenly he saw an irregularly shaped splash of brightness in the bottom of her right lung, in a place that should have been mostly dark. It looked like a tangle of vessels. He recognized it immediately. It was a pulmonary arteriovenous malformation, or PAVM, an abnormal connection between a pulmonary vein and an artery."
(i) Arteriovenous malformation is rare, but can be anywhere in the body: brain, gastrointestinal tract (GI tract, 肠胃道) etc. This disease is usually taught in neurology 神经内科, whose rupture within skull is catastrophic.
(A) In CT scan without contrast medium, lungs (filled with air) look black, and bone is the whitest. Blood vessels are not visible, unless they are major vessels, such as aorta 主动脉 and inferior vena cava 下腔静脉.   
(B) Injection of contrast medium into blood vessels (arterial or venous, depending on goals), which brings about angiography 血管摄影术, makes blood white in X-ray or CT scan. Of course blood circulates, and a radiologist will, at the right time, pay attention to the region he is interested in. I will deal with lungs.  Contrast medium would make lung a little whitish than without contrast medium, due to contrast medium in myriad capillaries throughout the lungs. However, after medium passes through normal blood vessels, it is temporarily retained by AVM, tumors etc, because abnormal vessels in the latter are tortuous, fragile (causing leaks internally) and take time to pass through. So you see a grayish blur.

(d) 孝金波, 医生:脑血管畸形患者在情绪激动、受撞击时易发病. 人民网, Aug 1, 2013
(i) The report did not say whether the patient had premonitions of
(ii) Some people in China did not believe the autopsy, because the deceased had no representative present during the autopsy.
(iii) Generally speaking, before eventual rupture of AVM causing stroke or death, the patient will experience headquakes, resulting from leakages of blood from AMV.
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 楼主| 发表于 3-26-2018 12:41:13 | 显示全部楼层
(e) AVM

Before you read (f), Here are some illustrations and CT scans that will help you to visualize AVM.
(i) illustrations:
Note the increasing diameters of vein (due to high blood flow) and, later, the feeding artery (also known as feeder artery; to supply oxygen and nutrients to affected area).
(A)  Spinal Arteriovenous Malformation (AVM). Mayo Clinic, undated
https://www.mayoclinic.org/disea ... causes/syc-20355613
(B) Pacific Neuroscience Institute, undated.
https://www.pacificneurosciencei ... Malformation-02.jpg
(C) X-ray and surgical view:

Bhatoe HS, Operative Nuances of Surgery for Cortical Arteriovenous Malformations: A Safe Solution and Permanent Cure. Neurology India, 64: Suppl S1: 101-109 (2016).
http://www.neurologyindia.com/vi ... 7_101_178061_f7.jpg
("Figure 7: (a) DSA showing the AVM with dilated venous drainage. (b) Operative appearance of the draining vein after dural opening. (c) Operative appearance after dissection of the AVM and division of the arterial feeders")
(ii) digital subtraction angiography (DSA)
(a fluoroscopy technique; Images are produced using contrast medium by subtracting a "pre-contrast image")
(A) Here the angiography has black vessels. It just reversed the image: black <--> white).
(B) Figure 7(b) and (c) were mislabeled, and should have switched.
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 楼主| 发表于 3-26-2018 12:42:01 | 显示全部楼层
本帖最后由 choi 于 3-26-2018 12:45 编辑

(f) AVM
(i) arteriovenous malformation
("The resultant sign, audible via stethoscope, is a rhythmic, whooshing sound caused by excessively rapid blood flow through the arteries and veins. It has been given the term 'bruit,' French for noise. On some occasions, a patient with a brain AVM may become aware of the noise, which can compromise hearing and interfere with sleep in addition to causing psychological distress")

gives an excellent overview.

This Wiki page mentions bruit, which is defined:
bruit (n; from Old French bruit noise, from bruire to roar): "Medicine  a sound, especially an abnormal one, heard through a stethoscope; a murmur"
(ii) There is no need to read the rest of any information pages below.
(A) Arteriovenous Malformation Information Page. National Institute of Neurological Disorders and Stroke (NINDS), US National Institute of Health (NIH), undated
https://www.ninds.nih.gov/Disord ... on-Information-Page
("These malformations most often occur in the spinal cord and in any part of the brain or on its surface, but can develop elsewhere in the body. * * * Most often AVMs are congenital, but they can appear sporadically.  In some cases the AVM may be inherited * * * The greatest potential danger posed by AVMs is hemorrhage. * * *
(B) Arteriovenous Malformations. MedlinePlus, NIH, undated
("AVMs are rare. The cause is not known, but they seem to develop during pregnancy or soon after birth. Doctors use imaging tests to detect them")
(C) Hereditary Hemorrhagic Telangiectasia. Genetics Home Reference, National Library of Medicine (NLM), NIH, undated
https://ghr.nlm.nih.gov/conditio ... agic-telangiectasia

Click blue-barred "Genetic Changes": "Mutations in several genes, including the ACVRL1, ENG, and SMAD4 genes, cause hereditary hemorrhagic telangiectasia."

Mutation of these three genes (whose functions are unknown) are autosomal dominant.

English dictionary:
* telangiectasia (n; New "Latin, from Greek telos end + angeion vessel + ektasis dilatation) https://en.oxforddictionaries.com/definition/telangiectasia "also telangiectasis; a condition characterized by dilatation of the capillaries causing them to appear as small red or purple clusters, often spidery in appearance, on the skin or the surface of an organ"

, which demonstrates pronunciation /tɛˌlandʒɪɛkˈteɪzɪə/.  The American pronunciation, as shown in www.merriam-webster.com is /ˌte-ˌlan-jē-ˌek-ˈtā-zh(ē-)ə/. The differelies in the letter s.
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