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Pulmonary embolism

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					 Pulmonary embolism

ID: 1426292-8
Date of admission:90-10-22
Name: 謝美莉
sex:female
age:30y/o
     Chief complaint


Exertional dyspnea noted for 1 month
        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 小港 hospital for help. Treadmill test
was arranged. Due to personal reason, she came
to our ER for help.
At ER:
WBC:10820 Hgb:13.4       PLT:81k     CK:66
CK-MB:3.7 TnT<0.01       GOT/GPT:36/35
Sugar:132 BUN/Cr:14/1.0     Na/K/Cl:139/4.3/112
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.
          Past History
1.DM:(-)
2.H/T:(-)
3.Alcohol: (-)
Smoking: (-)
4.Other systemic disease: myoischemic (+) was
  ever told
5.Drug allergy: denied
 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,
Extremity:freely movable
Lower legs: pitting edema
                EKG

LeadⅠ: deep S
LeadⅢ: Q wave, reversed T wave
(S1Q3) => R/O pulmonary embolism
V1-4: QS wave, reversed T wave =>
R/O old anterior septal ischemic change
                   APS
* Anti-phospholipid syndrome
 (1). Lupus anti-coagulant(+)

  (2). Anti-cardiolipin Ab(+)

  (3). β2GP1 (+)
         Impression
1. Exertional dyspnea
   suspect CHF, IHD,
   pulmonary hypertension,
   pulmonary embolism

2. Thrombocytopenia
         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.
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.
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.
      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.
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 Homan’s 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.
  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.
* 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.
              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.
* 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.
           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 => indicate DVT even if no collaterals are
 seen.
(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.
               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 => the results are
 variable and hence diagnosis of calf DVT is not
 reliable unless a distinct “hotspot or segment” is
 identified on static images.
 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.
* In some types of RNV, both dynamic and static
 RNV are performed together.

* An array of radiopharmaceuticals which include:
 99mTc-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.
  Non-radionuclide study
CNV
* The ability to ascess the deep venous system
  for thrombi is CNV’s 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.
             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.
    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.
 => valid reasons

* A large percentage of patients who undergo
 RNV do not necessarily need concurrent lung
 perfusion study.
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.
* The low-pressure venous system is susceptible
 to external compressions by pillows, elastic
 bandages or stockings => false positive results.

* The static images tend to underestimate the
 presence of an extensive network of collaterals
 => 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.
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 => 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.
   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).
* 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 => 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.
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.
* 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(25.7%of the case) is
 the iliofemoral combination.

* When the iliac vein is occluded, 61% involved
 the left side.
  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.
* 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.
* 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 => 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.
            “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.)
(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.
RNV – ideal monitor for DVT

* CNV: due to morbidity => 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.
* 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.

				
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