Vascular Access
Using ultrasonography, evaluate the common femoral (or, if required, the right internal jugular) vein for patency and compressibility. If there is any thrombus or indwelling catheter, the approach may need to be altered. Clean and drape the site. Anesthetize the skin using appropriate anesthetic agent. Conscious sedation may be utilized depending on the clinical status of the patient. Avoid oversedation since patient cooperation and breath holding are imperative for good quality imaging.
Access the femoral (or right internal jugular) vein using the standard venous puncture protocol. Ultrasonography may be used as an adjunct, if needed. Sheath placement depends on operator preference.
Studies have shown high success rates with ultrasound-directed catheter pulmonary angiography for thrombolysis in massive and submassive pulmonary embolism. [22, 24]
Catheter Selection
Numerous articles have described a multitude of techniques for accessing the pulmonary arteries, some using specialized catheters and guidewires. [33, 34, 35, 36, 37]
The Grollman catheter, for example, is a preformed pigtail catheter that has a gentle rightward curve with a second 90° leftward curve at the distal aspect of the catheter; its distal tip is in a pigtail configuration (see the image below). This shape was designed for access from the right femoral vein and allows for easier maneuvering through the right heart and pulmonary arteries. [38]
Pulmonary angiography catheter. The Grollman catheter has a gentle curve along the distal portion, with a 90 degree bend 3 cm from the pigtail terminus. Permission for use granted by Cook Medical Incorporated, Bloomington, Indiana.
Multiple variations on this design have been produced, such as the St. Charles catheter. More standard catheters, such as the Omni-flush, may be used along with a malleable hydrophilic wire to shape the catheter. There is also a specialized C-shaped Hunter catheter for a brachiocephalic approach. [35] A Swan-Ganz catheter can also be used to flow directly into the pulmonary arterial circulation by inflating the balloon.
The Berman catheter is a balloon-tipped, end-capped, pressure-rated catheter that can be advanced through the right heart into the pulmonary artery. The end cap protects the distal pulmonary vasculature from injury during high-pressure injections. Multiple fenestrations along the catheter tip allow for pressure diffusion and rapid exit of contrast solution. [39]
The main principles for catheter and guidewire selection
Use a catheter that has side-holes, such as a pigtail, to decrease the risk of damaging the vasculature
Have some means of creating a 90° or near 90° angle within several centimeters of the distal portion of the catheter to improve maneuverability through the right heart. Use a preformed specialized catheter or gently bend the stiff end (back end) of a guidewire to create an angle in an otherwise straight catheter (make sure the guidewire always stays inside the catheter; otherwise, it will damage the vessel/mediastinal structures.)
Use a soft-tipped or tip-deflecting wire (eg, Reuter tip-deflecting wire) and protect the tissues from a regular-tip wire.
Intracardiac and Intrapulmonary Catheter Manipulation
After gaining central venous access, advance a 6-7F catheter into the right atrium under fluoroscopic guidance (see the image below). Continuous cardiac monitoring is imperative to assess for arrhythmia as the catheter traverses the heart.
Right femoral vein approach with the St. Charles catheter tip in the right atrium. Courtesy of Christopher Friend, MD.
Rotate the catheter such that the pigtail lies facing the tricuspid valve. Advance the catheter tip into the RV. Turn the catheter counterclockwise while advancing the catheter, and the pigtail should approach the main pulmonary artery (see the images below).
Digital subtraction angiography image shows the pigtail catheter in the main left pulmonary artery.
The left pulmonary artery is the continuation of the main pulmonary artery and is easily accessed by advancing the catheter placed in the main pulmonary artery.
Accessing the right pulmonary artery requires a sharp turn, and using a J-tipped guidewire may assist in accessing this vessel. Alternatively, a hydrophilic wire may sometimes be necessary to access the right pulmonary artery (see the image below).
Tip of catheter in the right pulmonary artery. A guidewire (arrowhead) was used for navigation.
For selective catheterization of segmental pulmonary arteries, a straight-tipped catheter, such as the Berenstein, may be used (see the image below).
Selective segmental branch pulmonary arteriogram is facilitated with use of a Berenstein catheter.
Pressure Measurements
Measuring pressures in the heart and pulmonary arteries may be necessary, especially when evaluating a patient with chronic thromboembolic disease. Typically, pressures in the right atrium, RV, and main pulmonary artery are measured. [40] When interpreting the images, evaluate for aberrant vessels, such as scimitar vein or anomalous coronary artery, particularly in the pediatric population. [41] Also assess the caliber and contour of vessels. Vessels should be free of filling defects and should taper gradually. Flow dynamics are also assessed. Finally, evaluate the timing of arterial, parenchymal, and pulmonary venous opacification.
Normal pressure values are as follows:
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Right atrium or central venous pressure, 3-5 mm Hg
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RV, 20-25 mm Hg
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Pulmonary artery, 20-25 mm Hg/10-15 mm Hg
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Pulmonary capillary wedge, 10-15 mm Hg
Image Acquisition
To obtain a diagnostic pulmonary angiogram, have the patient suspend respiration after a full inspiration during the injection of contrast material to minimize motion artifact. For most studies, it is recommended to obtain 3-4 images per second for the first 5 seconds and then 1-2 images per second for the remainder. The following views should be obtained for a complete study:
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Anteroposterior of each side (see the image below)
Normal right (A) and left (B) pulmonary angiograms showing gradual tapering of the pulmonary arteries, normal caliber vessels, and no filling defects.
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Posterior oblique projections of the lower lobes (see the image below)
(A) Anteroposterior angiogram of the right pulmonary artery shows no abnormality. (B) On the oblique view, a filling defect is visible posteriorly (arrow).
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Use magnification to interrogate any specific regions of interest (see the image below)
(A) Left pulmonary angiogram shows faint subsegmental filling defect in the lateral basal pulmonary artery that is imaged more clearly (arrow) on the magnified view (B).
To minimize the risk of adverse reactions, low osmolar nonionic contrast should be used. Typical injections rates are listed below. To help determine the rate of injection, evaluate the rate of flow through the selected artery using hand-delivered test injections; if contrast dissipates quickly, a higher rate should be used. Although the authors list injection rates for the main pulmonary artery to be complete, images from such injections are typically of poor quality, and injection here is therefore not advised. Selective right and left lung arteriograms yield better diagnostic images.
For patients with renal failure or other contraindications to iodinated contrast material, CO2 may safely be used as a contrast agent [42] ; however, imaging of the distal vasculature may be of poor quality. [43]
Injection rates
Injection rates are as follows:
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Main pulmonary artery, 25-30 mL/s for 2 seconds
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Left pulmonary artery or right pulmonary artery, 15-20 mL/s for 2 seconds
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Lobar or segmental, 5-10 mL/s for 2 seconds
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Pulmonary angiography catheter. The Grollman catheter has a gentle curve along the distal portion, with a 90 degree bend 3 cm from the pigtail terminus. Permission for use granted by Cook Medical Incorporated, Bloomington, Indiana.
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Right femoral vein approach with the St. Charles catheter tip in the right atrium. Courtesy of Christopher Friend, MD.
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Tip of catheter in the main pulmonary artery.
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Digital subtraction angiography image shows the pigtail catheter in the main left pulmonary artery.
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Tip of catheter in the right pulmonary artery. A guidewire (arrowhead) was used for navigation.
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Selective segmental branch pulmonary arteriogram is facilitated with use of a Berenstein catheter.
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Normal right (A) and left (B) pulmonary angiograms showing gradual tapering of the pulmonary arteries, normal caliber vessels, and no filling defects.
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(A) Anteroposterior angiogram of the right pulmonary artery shows no abnormality. (B) On the oblique view, a filling defect is visible posteriorly (arrow).
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(A) Left pulmonary angiogram shows faint subsegmental filling defect in the lateral basal pulmonary artery that is imaged more clearly (arrow) on the magnified view (B).
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Selective left pulmonary angiogram shows abrupt tapering of the segmental pulmonary arteries (arrow) with heterogeneous opacification of the parenchyma. Mean pulmonary arterial pressure was 40 mmHg. These findings are consistent with chronic pulmonary thromboembolism.
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(A) Selective right pulmonary arteriogram shows large filling defects in the right upper (short arrow) and right lower (long arrow) lobe pulmonary arteries. In another patient, selective right pulmonary arteriogram (B) shows a filling defect in the right upper lobe pulmonary artery (arrow), which correlates with a large segmental filling defect (black arrows) on V/Q scan (C).
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PA chest radiograph shows right subclavian port with a fractured fragment in the right lower lung (arrow). B: Fluoroscopic intraprocedure image with a snare (long arrow) tethering the catheter fragment (short arrow).
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(A) Selective interlobar right pulmonary arteriogram shows large AVM in the lateral right lower lobe (arrow). (B) On late arterial phase imaging, there is early opacification of an inferior right pulmonary vein (arrow heads) draining the AVM. (C) Postembolization arteriogram shows occlusion (arrow) of the supplying artery to the AVM.
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(A) Pulmonary arteriogram shows irregular contour to the main (arrow) pulmonary artery with abrupt cutoff in the expected region of the left pulmonary artery (arrowhead) and attenuation of the proximal right pulmonary artery (white arrow). (B) Perfusion image from a VQ scan shows no activity in the left lung (oval), correlating with complete occlusion of the left pulmonary artery seen on angiography.
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(A) Anteroposterior chest radiograph shows increased lung volumes and marked radiolucency of the right upper lung in a patient with severe emphysema. (B) Right pulmonary arteriogram shows thin, severely tapered segmental arteries in the right upper lobe with increased space between vessel. Contrast this appearance with chronic pulmonary embolism (above), in which the space between arteries is normal.
