Digital subtraction pulmonary angiography (DSPA) is the definitive test for evaluating diseases of the pulmonary vasculature like pulmonary embolism. It allows visualization of all pulmonary arterial branches and therapeutic interventions. DSPA involves percutaneous venous catheterization and injection of iodinated contrast agents to produce images of the pulmonary arteries and veins. While it remains the criterion standard, DSPA has risks like acute cor pulmonale in patients with pulmonary hypertension and operator dependency remains a concern due to potential 10-15% interobserver variability in examining small vessels.

1. PULMONARY ANGIOGRAPHY
DR. KRUPASAGAR.K

2. Digital Subtraction Pulmonary Angiography
DSPA is the criterion standard or definitive test in evaluating diseases
involving the pulmonary vasculature.
- In the diagnosis of PE and other arterial and venous disorders.
- Allows visualization of all pulmonary arterial branches.
- Allows catheter-based measurement of pulmonary artery pressure, and
-Therapeutic interventions
viz. foreign body retrieval, catheter-directed thrombo fragmentation,
embolectomy for PE; transcatheter embolization for pulmonaryAVMs and
pulmonary arterial pseudoaneurysms.

3. Currently, conventional or cut-film angiography is not used.
The method is time consuming and labor intensive, and it requires the use of a
relatively large amount of contrast material.
Technique: percutaneous venous catheterization,
intracardiac catheter manipulation, and
catheterization of the pulmonary artery.
Ionizing radiation and iodinated contrast agents - to produce
images of the pulmonary arteries and veins.

4. This procedure can be performed rapidly and safely with minimal discomfort
to the patient.
Catheters - cause less traumatic effects
- more easily controlled
-Less manipulation required to catheterize the pulmonary arteries
- the risk of cardiac perforation has been eliminated.
Pulmonary angiography. Right pulmonary
angiogram shows an arterial branch in the
right lower lobe that leads into a focal
dilated vascular nidus at the periphery of
the lung.

5. DSPA can be performed by using
The right common femoral vein
The jugular vein or Brachial vein.
The injection is made within each of the main pulmonary arterial branches and
is positioned so as to allow all of the lobes of one lung to be well opacified.
More selective injections may be performed when needed, although with a
smaller volume of contrast agent and decreased injection pressure.
Rapid-sequence images are acquired in multiple anteroposterior and oblique
projections, depending on the indications of the study.

6. 7F pigtail catheter is the standard choice because of
the rigidity and maneuverability .
the shape virtually eliminates perforation of the vessel wall, and
its distal side and end holes allow the rapid delivery of a bolus of contrast
agent without any significant risk to the vessel wall.
The stiff end of a routine guidewire is shaped and advanced to near the apex of
the pigtail;
it is directed across the tricuspid and pulmonic valves from the right atrium.
Some interventional radiologists prefer the Grollman catheter, with its
smaller and angled pigtail design.
Other catheters currently in use are also designed with a distal curve and a
small pigtail tip.

7. the most significant complication is acute corpulmonale.
almost always related to a history of pulmonary hypertension.
Deaths-- 0.2% in patients with severe pulmonary hypertension (>70 mm Hg)
Patients blood pressure was low after the injection of dye
followed by apnea and cardiac arrest, and
death ensued despite resuscitative efforts.
pulmonary angiography can be performed more safely by tailoring the
examination to the individual patient.
Distal main or lobar pulmonary artery injections with reduced flow rates can
target the site of suspected abnormality.

8. Hypertonicity of the contrast agent causes
elevation in pulmonary artery and right ventricular pressures.
Hence, the use of nonionic agents may prove to be safer in this regard.
The wide array of contrast media-- iso-osmolar and hypo-osmolar
ionic and nonionic agents.
The operator dependency in radiographic interpretation remains a concern.
The rate of interobserver variability can approach 10-15%,

9. major risk factors in pulmonary angiography
the presence of a left bundle branch block,
a history of ventricular irritability,
or a recent myocardial infarction.
In the presence of a left bundle branch block, the transient right bundle branch
block that may occur when the catheter is passed through the right heart may
result in complete heart block.

10. The electrical system on the right side of the heart is often irritated during
catheter and guidewire manipulation, especially in the right ventricle.
severe elevation in pulmonary arterial pressure.
Therefore, a temporary pacemaker should be in place before the procedure is
performed. In the population with these conditions, use of DSPA should be
questioned, because PTCA feasible alternative.
pulmonary angiography has morbidity (2-5%) and mortality (0.2%) rates lower
than those of empiric anticoagulation (5-25% and 1-2%, respectively), it has
not gained widespread acceptance, and it is not universally available.

11. Although pulmonary angiography remains the criterion standard, the operator
dependency in radiographic interpretation remains a concern.
The rate of interobserver variability can approach 10-15%, and it may be
even higher in the examination of smaller vessels.
Presence of a thrombus, which appears as a filling defect or as a sudden
cutoff of blood flow in a pulmonary arterial branch, establishes the diagnosis
of PE.
The angiographic signs of PE include a partial filling defect within a
contrast-filled vessel and complete occlusion of the vessel, producing an
abrupt vascular cutoff