Catheter-Directed Thrombolysis (CDT) in Lower Extremity DVT
Overview
Thrombolytic agents:
- activate
plasminogen → plasmin
- accelerate
clot lysis
ปัจจุบันนิยม:
- catheter-directed
thrombolysis (CDT)
มากกว่า systemic thrombolysis
Goals of thrombolysis
ใน selected severe DVT:
- rapidly
dissolve thrombus
- relieve
severe symptoms
- restore
venous outflow
- prevent
venous gangrene
- reduce
severity of post-thrombotic syndrome (PTS)
Important principle
Most DVT patients ไม่ต้อง thrombolysis
Standard treatment ส่วนใหญ่:
- anticoagulation
alone
เพราะ thrombolysis:
- bleeding
risk สูงขึ้น
- ไม่ลด mortality/recurrent VTE ชัดเจน
Patients suitable for thrombolysis
Main indications
Extensive proximal/iliofemoral DVT ร่วมกับ:
- severe
symptomatic swelling
หรือ - limb-threatening
ischemia
โดยเฉพาะ:
- phlegmasia
cerulea dolens (PCD)
Additional practical criteria
มักเลือกผู้ป่วยที่:
- symptoms
<14 days
- good
functional status
- life
expectancy >1 year
- low
bleeding risk
Possible candidates
- extensive
iliofemoral DVT
- severe
refractory symptoms despite anticoagulation
- threatened
limb
- venous
gangrene risk
NOT routinely indicated
Uncomplicated DVT
เพราะ:
- bleeding
↑
- no
clear mortality benefit
- no
clear recurrent VTE reduction
Contraindications
ใช้หลักคล้าย PE thrombolysis
Important contraindications:
- active
bleeding
- recent
intracranial hemorrhage
- recent
major surgery
- severe
uncontrolled HT
- intracranial
neoplasm
- severe
thrombocytopenia
Initial management before CDT
Start anticoagulation immediately
Preferred:
- IV
UFH
หรือ - LMWH
พร้อม:
- bed
rest
- limb
elevation
Preferred thrombolysis method
Catheter-directed thrombolysis (CDT)
Preferred over systemic thrombolysis เพราะ:
- lower
total drug dose
- less
bleeding
- more
targeted clot lysis
Systemic thrombolysis
ปัจจุบัน:
- rarely
used
ใช้เฉพาะ:
- CDT
unavailable
- cannot
transfer
- concurrent
massive PE
CDT technique
Catheter ใส่เข้า thrombus โดยตรงผ่าน:
- popliteal
vein
- common
femoral vein
- internal
jugular vein
- posterior
tibial vein
Imaging during procedure
ใช้:
- venography
- ±
intravascular ultrasound (IVUS)
เพื่อ:
- define
clot burden
- detect
May-Thurner syndrome
- identify
stenosis
Thrombolytic agents
Most commonly:
tPA (alteplase)
Typical infusion rate:
tPA approx 0.5-1 mg/hr
Mechanical thrombectomy (MT)
สามารถใช้ร่วมกับ CDT:
- aspiration
- rotational
- rheolytic
- ultrasound-assisted
devices
Advantages:
- faster
reperfusion
- less
thrombolytic exposure
Anticoagulation during CDT
Usually continue UFH
แต่ใช้ lower intensity
Example:
- reduced
UFH infusion
- omit
bolus
หลัง CDT:
- return
to therapeutic anticoagulation
Monitoring during CDT
ต้อง monitor:
- symptom
improvement
- swelling
- pulses/Doppler
signals
- neurologic
status
- signs
of PE
- bleeding
Laboratory monitoring
ทุก ~6 hr:
- fibrinogen
- anti-Xa/aPTT
Daily:
- CBC
Important fibrinogen threshold
บาง center หยุด infusion
หาก:
Fibrinogen <100 mg/dL
Repeat venography
มักทำ:
- 12–24
hr หลังเริ่ม infusion
ประเมิน:
- continue
vs stop infusion
- thrombectomy
need
- underlying
stenosis
Typical duration
ส่วนใหญ่:
- 24–48
hr
rarely >48 hr
Follow-up anticoagulation
หลัง CDT:
- therapeutic
anticoagulation ต่อทันที
มักเริ่มภายใน:
12-24 hr after CDT completion
นิยม:
- apixaban
- rivaroxaban
Complications
Bleeding
Most common complication
Major bleeding
Major bleeding <2%
Intracranial hemorrhage
ICH <1%
Other complications
- PE
from clot fragmentation
- catheter
hematoma
- infection
- vessel
perforation
- reperfusion
swelling
- compartment
syndrome
Evidence summary
Benefits
Compared with anticoagulation alone:
- faster
clot lysis
- improved
venous patency
- may
reduce severity of PTS
- symptom
relief better
Limitations
No clear reduction in:
- mortality
- recurrent
VTE
ATTRACT trial pearls
Pharmacomechanical CDT:
- no
overall PTS reduction
- no
mortality benefit
- bleeding
increased
แต่ severe iliofemoral DVT:
- moderate/severe
PTS อาจลดลง
Mechanical thrombectomy alone
Useful in:
- high
bleeding risk
- failed
thrombolysis
- thrombolysis
contraindication
Surgical thrombectomy
ใช้เมื่อ:
- endovascular
unavailable
- failed
CDT/MT
- severe
threatened limb
IVC filter
พิจารณาใน:
- contraindication
to anticoagulation
- high
embolic risk
- thrombectomy/high
clot burden
Patients unsuitable for thrombolysis
- uncomplicated
DVT
- high
bleeding risk
- poor
functional status
- limited
life expectancy
- chronic
clot >14 days
Clinical pearls
- CDT
preferred over systemic thrombolysis
- thrombolysis
reserved for severe/extensive iliofemoral DVT
- phlegmasia
cerulea dolens = emergency indication
- UFH
usually continued during CDT
- monitor
fibrinogen and bleeding closely
- mechanical
thrombectomy increasingly favored
- thrombolysis
improves clot lysis but not mortality
- bleeding
risk remains major limitation
- uncomplicated
DVT → anticoagulation
alone remains standard
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