Pulmonary embolism

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Pulmonary embolism

• ID 1426292-8
• Date of admission90-10-22
• Name ???
• sexfemale
• age30y/o

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Chief complaint

• Exertional dyspnea noted for 1 month

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Present illness

• This 30y/o woman was well before. Unfortunately,
  she suffered from exertional dyspnea one month
  ago. Exertional dyspnea occurred during her MC
  period. According to her statement, symptom/sign
  subsided after the finish of MC period. But it
  attacked again 1wk ago. In addition, syncope,
  dizziness, cold sweating, chest pain,
  epigastralgia, and nausea/vomiting was noted. She
  went to ?? hospital for help. Treadmill test was
  arranged. Due to personal reason, she came to our
  ER for help.

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At ER WBC10820 Hgb13.4 PLT81k
CK66 CK-MB3.7 TnTlt0.01 GOT/GPT36/35
Sugar132 BUN/Cr14/1.0 Na/K/Cl139/4.3/112
Under the impression of (1). Extertional dyspnea.
(2). Thrombocytopenia. She was arranged to get
admission for further survey and management.
After admission to 11C, the diagnosis of acute
pulmonary embolism was made. At once,
heparinization and anticoagulant drug was given.
However, the poor clinical improvement was noted.
The pulmonary angiography was performed. Because
of (1). The persisted pulmonary embolism. (2).
APS. She was transferred to the CCU for
thrombolytic treatment.
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Past History

• 1.DM(-)
• 2.H/T(-)
• 3.Alcohol (-)
• Smoking (-)
• 4.Other systemic disease myoischemic () was
  ever told
• 5.Drug allergy denied

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Physical examination

• Consciousness clear
• Head Conjunctiva not anemic
• Sclera icteric
  
• Neck supple LAP (-) JVE (-)
  
• Chest symmetric expansion
• Heart sound RHB, no murmur
• Breath sound rale over left basal area
  
• Abdomen soft flat
• Bowel sound normoactive
• Tenderness () over epigastralgia area,
• Extremityfreely movable
• Lower legs pitting edema

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EKG

• Lead? deep S
• Lead? Q wave, reversed T wave(S1Q3) gt R/O
  pulmonary embolism
• V1-4 QS wave, reversed T wave gt R/O old
  anterior septal ischemic change

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APS

• Anti-phospholipid syndrome
• (1). Lupus anti-coagulant()
• (2). Anti-cardiolipin Ab()
• (3). ß2GP1 ()

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Impression

• 1.  Exertional dyspnea
• suspect CHF, IHD,
• pulmonary hypertension,
• pulmonary embolism
• 2.  Thrombocytopenia

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Image Finding

• Date 10/25
• Tc99m MAA pulmonary perfusion/Tc99m DTPA
  aerosal ventilation scintigraphy
• From the both perfusion and ventilation images,
  the findings are shown as
• (1). Relatively delayed pulmonary perfusion in
  the bilateral lung fields.
• (2). Multiple segmental perfusion defects in the
  bilateral lung fields, including the right
  low basal, middle segments and left
  basal segments, upper segment.
• (3). Borderline cardiomegaly.
• (4). No overt abnormality in the correlated
  lung fields on the chest CT. 
• Imp High probability of pulmonary embolism.

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• 11/12
• Tc99m MAA pulmonary perfusion/Tc99m DTPA
  aerosal ventilation scintigraphy
• From the both perfusion and ventilation
  images, the findings are shown as
• (1). Significant improvement of pulmonary
  perfusion in the bilateral lung field, compared
  with previous survey(10/25)
• (2). But still persistent segmental V/Q mismatch
  in the right post, apical, superior
  segments and left post apical and inguinal
  portion.
• (3). Uneven perfusion in the bilateral lung
  field.
• (4). Cardiomegaly.

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• 11/14
• Imaging findings
• Tc-99m RBCs subcutaneous radionuclide
  venography(SC-RNV)
• 1. Dynamic Study
• faint deep venous return in the calf and
  communicating into the collateral in the
  right leg smooth deep venous return in the
  left leg.
• 2. Static Study(after removing tourniquet in the
  bilateral ankles)
• dominant collateral flow with faint deep
  venous return in the bilateral legs, and more
  reduced deep venous flow in the right.

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Venous thrombosis

•    About 60-80 pulmonary emboli (PE) arise from
  thrombi of the lower extremity veins, while 15
  arise from the pelvic veins.
•     In other series more than 90 of pulmonary
  emboli originates from deep vein thrombosis(DVT).
• Early diagnosis and treatment of DVT can
  constitute a preventive measure against PE.
•     DVT does not cause death but PE contribute
  to moartality.

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Reasons for underdiagnosed of DVT

•    The thrombi may be clinically silent or the
  clinical features of DVT are atypical.(The usual
  S/S to diagnose DVT tachycardia, low grade
  fever, localized tenderness, pain, increased skin
  temperature, redness, swelling, oedema, and
  positive Homans sign- are not specific.)
•     Contrast venography(CNV) the age-old gold
  standard since 1934, has a poor patient and
  physician acceptance.
•     Radionuclide venography(RNV) There remains
  some familiarity and perhaps scepticism regarding
  the overall worthiness of RNV in the diagnosis of
  DVT.

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99m Tc pertechnetate

•   The decision to use 99mTcO4 permits the use of
  a much larger dose.
• Theoretically, electrostatic attraction is
  better achieved with plain pertechnetate of its
  much smaller molecular size.
• ? Large volume
•     The large volume makes it easier to
  apportion the radiopharmaceutical during the
  slow and simultaneous but continuous
  intravenous injections.

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•     The larger volume also permits a relatively
  wider coverage of the venous network because of
  a fuller filling of the overall deep venous
  system.
•    In post-phlebitic syndrome or in patients
  with full-blown varicosities, it is almost
  mandatory that large volume is used.(Venous
  capacitance has greatly increased)
•    The entire procedure consists of the
  ascending dynamic and static RNV, usually takes
  less than 12min to complete.

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Tourniquet

•    The whole premise of tourniquet application
  is to prevent or minimize the passage of the
  contrast material into the superficial veins and
  concurrently deflect a larger volume to the deep
  venous system, thereby improving image
  resolution.
•     Its use in CNV may be necessary because the
  required volume of contrast material is far
  greater than that ordinarily used in RNV.

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•    Another reason for its use To minimize or
  altogether obviate problems related to the
  layering and streamlining of contrast
  material.(which are not problems in RNV since the
  N/S readily mixs with circulating blood.)
•    The tourniquets are unnecessary generally
  since 74 of RNV studies automatically outline
  the popliteal / femoral vein.( If given adequate
  time, most of the deep venous system can be
  outlined)
•    Tiny fragile dorsal pedal veins are
  frequently the only routes available for the
  injection.

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Modifications

• (1)
•    If the popliteal / femoral vein failed to be
  outlined in the ipsilateral symptomatic limb, a
  tourniquet is tightly applied above the ankle
  joint during the second injection.
•    The persistent non-visualization of the
  popliteal/ femoral veins, especially when
  accompanied by pain gt indicate DVT even if no
  collaterals are seen.

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• (2)
•    Anterior static images of the pelvis and both
  lower extremities are performed and, in the case
  of the limbs, an additional frog-leg position
  of each extremity is obtained.
•    Static RNV permits to differentiate between
  acute versus chronic DVT.
•    frog-leg position unbundles the superficial
  from the deep varices when these are present.

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Limitation

•    RNV identifies the site of occlusion, but
  does not identify the thrombus inself.
•    It is unable to distinguish between
  extraluminal or intraluminal causes of
  obstruction except on some occasions.
•    Distal to the popliteal veins gt the results
  are variable and hence diagnosis of calf DVT is
  not reliable unless a distinct hotspot or
  segment is identified on static images.

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Types of studies for diagnosis of DVT

•    Consist of non-radionuclide and radionuclide
  studies.
•    CNV and Doppler/US The most widely used
  non-radionuclide procedures.
•     Radionuclide procedures consist of both
  non-imaging (ex 125I-labelled fibrinogen uptake
  test ) and imaging studies.
•    Two general types of RNV
• (1). Ascending dymanic RNV best mimics
  CNV, injection is through the pedal veins.
• (2). Static RNV in some types, injection
  is done antecubitally.

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•    In some types of RNV, both dynamic and static
  RNV are performed together.
•    An array of radiopharmaceuticals which
  include99mTc-MAA, 99mTc-HAM, 123I or 125I
  fibrinogen, radiolabelled streptokinase,
  urokinase, 99mTc plasmin, 99mTc RBC, large
  volume 99mTcO4 have been introduced to
  perform RNV.
•     Each RNV has its own merits and limitations,
  its own proponents and detractors.
•     An optimally performed RNV, if negative,
  does exclude the presence of DVT, so it is
  reasonable to advocate it as a screening
  procedure of DVT.

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Non-radionuclide study

• CNV
•    The ability to ascess the deep venous system
  for thrombi is CNVs primary edge over other
  procedures.
•    It fails to distinguish between recent and
  residual(old) thrombi.
•    The procedure has 7.5-24 related morbidity.
•     Poor patient acceptance.
•     It cannot be performed in patients with a
  swollen lower extremities or in patients with a
  history of contrast reaction.

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Doppler/US

•    Doppler/US are usually performed together as
  one study.
•    Doppler measure deep vein blood flow
  velocity.
•    A high degree of diagnostic accuracy in
  patients with initial episodes of DVT.
•    When deep veins are not easily compressible
  during the study, the specificity and sensitivity
  drop significantly when compared with CNV.
•    Resolution in the pelvis and thigh is poor.
•    It fails to distinguish between recent and
  chronic thrombi.
•    Drawback limited field of view.

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Other types of RNV

• 99mTc-HAM or 99mTc-MAA
•   Arguments There is no recirculation of
  radiopharmaceutical and a lung perfusion
  scintigraphy can subsequently be performed
  without a separate injection being administered.
  gt valid reasons
•    A large percentage of patients who undergo
  RNV do not necessarily need concurrent lung
  perfusion study.

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99mTc RBC radionuclide venography

•    99mTc RBC venography has high sensitivity and
  specificity exceeding 90.
•    Drawback Tagging efficiency is influenced
  negatively by a large range of commonly used
  medications, contrast agents and RBC Ab.
• The procedure requires strict symmetric
  position of limbs a minimal variance which give
  rise to some limb rotation will interfere with
  the accuracy.

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•    The low-pressure venous system is susceptible
  to external compressions by pillows, elastic
  bandages or stockings gt false positive results.
•     The static images tend to underestimate the
  presence of an extensive network of collaterals
  gt take away important clue in diagnosis of DVT.
•     Inefficient labeling, cross-activity from
  the arterial system becomes a major sourse of
  interference.
•     It does not differentiate between acute and
  chronic DVT.

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Radiolabelled platelet and antiifibrin RNV

•    It not only diagnose but also monitor
  directly the efficacy of therapy instituted.
•     Since heparin may reduce the sensitivity of
  technique gt therapy require discontinuation.(But
  some people deny it.)
•     It is accurate in the calf and popliteal
  area, has low sensitivity In the thigh and
  pelvis.

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Normal scintigraphic features

•    The normal ascending dynamic RNV outlines the
  IVC and the common iliac, external iliac, femoral
  and popliteal veins. Peroneal vein, ant. or post.
  tibial vein or saphenous vein is also
  identified.
•     Normal configuration easily resembles a
  wishbone or an inverted Y with long arms.
•     Iliac vein may show slightly less intense
  activity.(esp.attenuate in pts with capacious
  abdominal girth or massive ascites).

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•    The left iliac vein is relatively longer and
  has a generally more horizontal and superiorly
  curved course than the right. This apparently
  explains its greater vulnerability to extrinsic
  compression by pelvic masses or lesions gt
  results in the higher incidence of left-sided
  occlusion of deep venous system.
•     Right common iliac artery as it branches
  out of the abdominal aorta , compresses the left
  common iliac vein as it joins the contralateral
  vein to become the IVC.
•     The static RNV also outlined all the major
  deep veins described above with relatively less
  intensity.

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Abnormal scintigraphic features

• Sites and sides of DVT
•    DVT occurs frequently at venous bifurcations
  since the angulations at these junctions may
  create some slowing of venous flow.
• Three common sites (1) iliofemoral, (2)
  femorosaphenous (3) external-internal iliac
  junctions.

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•   Sites where structures that normally compress
  veins are susceptible sites of thrombi
  formation.
•    82 if cases of DVT involve one side of the
  deep venous system 18 of cases are
  bilateral.(usually seen at the level of
  iliofemoral junctions.)
•   DVT involves external/common iliac, femoral
  and popliteal veins either singly or in
  combination. Of the multiple contiguous veins
  involved, the most common(25.7of the case) is
  the iliofemoral combination.
• When the iliac vein is occluded, 61 involved
  the left side.

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Scintigraphic features

• Ascending dynamic RNV
•    Non-visualization of a major vein(usually the
  common iliac, ext. iliac, femoral or popliteal.)
•     Rule of a thumb occlusions at the iliac
  levels are associated with rich collateral
  formations and at the popliteal level a paucity
  or absence of collaterals.
•     The extent of the network of collaterals
  depends directly on the degree, size and age of
  the thrombus.
•     The dynamic RNV often demonstrates more
  vividly than conventional CNV the presence of
  rich collaterals.

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•    In some case, non-visualized vein of the
  thrombosed vein is the sole sign of occlusion. It
  is frequently seen at two sites popliteal vein
  level and femorosaphenous junction.
•    Frequently, non-visualization is due to a
  more localized and distal thrombus.
•    The ascending dynamic RNV indentifies the
  site of distal occlusion but does not necessarily
  indicates the degree or the proximal extent of
  the thrombus.
•    Despite the presence of complete deep vein
  occlusion, there is an absence or a paucity of
  small networks of collaterals.

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•    A middle pelvic abscess which compresses the
  left iliac vein shows a rich network of
  collaterals.
•    Late and asymmetrical arrival of activity on
  one side of the deep venous system as a sign of
  occlusion on that side gt But other causes must
  be excluded.(ex post-phlebitic syndrome or the
  presence of deep or superficial varicose veins)
•    Some static RNV depend solely on the presence
  of so-called hotspots along the course of deep
  venous system.

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Hotspots

•    (1). Indicate uptake by the newly formed
  thrombi.(2). Have been observed in large
  dysfunctional
• vein valves, sites of soft-tissue
  infections,
• post-phlebitic syndrome, varicose
  veins
• (3). Newly formed larger thrombus of the
  pelvis
• have failed to demonstrate hotspots
  by
• radiolabelled anti-fibrin.(attributed
  to the
• inability of the anti-fibrin radical
  to adhere to
• or penetrate the core if the large
  thrombi.)

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• (4). Using anti-fibrin or platelets are better
  than
• using 99mTc-HAM or 99mTc-MAA
• (5). Reliable sign of acute DVT
  particularly when
• they are segmental rather than
  focal, and there
• is a smudgy backdrop along with
  network
• collaterals.

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RNV ideal monitor for DVT

•    CNV due to morbidity gt poor pts and
  physician acceptance
•     Doppler/US and IPG have their own inherent
  limitation.
•     RNV are optimally suited for repeat studies
  of already established DVT.

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•    If the anti-thrombin or enzyme therapy has
  successfully prevented additional thrombi
  formation, and the thrombus is lysed, the
  disappearance of collaterals and some
  recanalization are seen.
•     Early recanalization occurs usually within
  10-12days.
•    The site of thrombosis is usually narrower
  and fainter in outline, and traces of residual
  collaterals in the appropriate site linger.
•    If the thrombus is not lysed, the initial
  observed collaterals are fortified and appear
  more graphic, while the occluded vein remains
  non-visualized.