Intraluminal vascular ultrasound: preliminary report of dimensional and morphologic accuracy

In Vivo Assessment of Ascending and Arch Aortic Compliance

BACKGROUND

Dynamic compliance (Cd) of the adult thoracic ascending and arch aorta has had limited in vivo evaluation in patients with aortic disease. This study evaluates aortic compliance using intravascular ultrasound (IVUS) across a range of thoracic aortic diseases.

METHODS

Seventy-nine patients undergoing thoracic aortic endovascular procedures had Cd measurements of the ascending aorta proximal to the origin of the brachiocephalic trunk and distal to the origin of the left common carotid artery using IVUS before endograft deployment. Cd was calculated for each segment using the following equation, Cd = ΔD/(D • ΔP) where ΔD = change in aortic diameter, D = diameter in diastole, and ΔP = pulse pressure.

RESULTS

Mean Cd of the ascending aorta in all patients (18.4%/mm Hg) and aortic arch (16.5 %/100 mm Hg) did not differ significantly. Compliance was significantly lower in patients being treated for thoracic aortic aneurysm and penetrating ulcer than in patients with traumatic rupture, acute and chronic dissection (P = 0.009). Compliance was significantly higher in patients with aortic transection compared with thoracic aneurysm or penetrating ulcer (P = 0.001). Compliance decreased with age by 0.44 ± 0.06 (P = 0.001) per year in the ascending aorta and 0.41 ± 0.05 (P = 0.001) per year in the aortic arch. Compliance did not increase with diameter when adjusted for age (P = 0.65). Compliance measured in the ascending aorta in 7 patients after descending thoracic aortic endograft repair decreased to 12.6%/100 mm Hg, although not significant (P = 0.18).

CONCLUSIONS

Ascending and aortic arch compliance is significantly higher than reported for peripheral vessels. Thoracic aortic compliance decreases with age and is not related to aortic diameter. The results of the present study are important when considering the development of endoprosthesis devices and long-term effects on the thoracic aorta.

Biplane Color Flow Duplex Intravenous Intravascular Ultrasound for Arterial Visualization

Purpose:

To describe a feasibility study in a sheep model using an intravascular ultrasound (IVUS) instrument in an intravenous position to produce color flow, B-mode images of arterial segments along with Doppler blood flow velocities.

Methods:

Four healthy adult male sheep were anesthetized for surgical exposure of the right external jugular vein. A 9.0F sheath was also introduced in the common femoral artery for arteriography and device insertion. A 7.5-MHz ultrasound probe with 1-cm graduation markers was passed into the jugular vein. B-mode and color flow pictures were captured at aortic branches in cross and longitudinal sections. Length measurements between aortic branches and Doppler spectral velocities were obtained. Guidewire, balloon, and stent maneuvers were monitored by the stationary intravenous IVUS probe.

Results:

High-quality visualization of the entire abdominal aorta and its branches was achieved in all animals. With the probe stationary in the vena cava, a 1.5-cm linear segment of the aorta could be continuously observed in both B-mode and color flow ultrasound scans. Insertion and implantation of a Palmaz balloon-expandable stent was guided by intravenous IVUS alone. Selective catheterization of the right renal artery was followed visually by moving the intravenous IVUS probe sequentially.

Conclusions:

Intravenous IVUS appears feasible as a guidance and monitoring tool for endovascular interventions. While conventional IVUS provides only cross-sectional images in B-mode, intravenous IVUS captures color flow and Doppler velocity data as well. These added ultrasound modalities may offer potential advantages for guidance of endovascular procedures and endoleak detection.

Intravenous Intravascular Ultrasound for Arterial Visualization: A Feasibility Study

Purpose:

The advent of endovascular grafting has created detailed imaging requirements for which intravascular ultrasound (IVUS) may be useful. Since intra-arterial IVUS imaging uses space within endovascular graft delivery systems and risks embolism, we investigated the use of intravenous IVUS imaging of arterial vasculature and endovascular grafts, a technique that appears not to have been previously described.

Methods:

IVUS catheters with 12.5- and 20-MHz transducers were inserted through the common femoral artery and vein of mature sheep. Transcutaneous images were also obtained with a 5-MHz linear transducer. B-mode images of the aortoiliac arterial segments and diameter measurements were recorded from both access vessels using anatomic landmarks for site localization. To assess device visualization from the intravenous image source, studies were done in vessels containing previously placed endovascular stent-grafts.

Results:

In this feasibility study, comparison among intravenous IVUS, arterial IVUS, and external ultrasound indicated equal diameter precision and ability to recognize arterial structures. Comparison of arterial diameter, whether obtained from an arterial, venous, or transcutaneous source, showed similar values.

Conclusions:

We conclude that it is probable for such techniques to be usefully applied to human aortoiliac arterial segments and that further investigation of arterial visualization from adjacent venous structures is warranted.

Biplane color flow duplex intravenous intravascular ultrasound for arterial visualization

PURPOSE

To describe a feasibility study in a sheep model using an intravascular ultrasound (IVUS) instrument in an intravenous position to produce color flow, B-mode images of arterial segments along with Doppler blood flow velocities.

METHODS

Four healthy adult male sheep were anesthetized for surgical exposure of the right external jugular vein. A 9.0F sheath was also introduced in the common femoral artery for arteriography and device insertion. A 7.5-MHz ultrasound probe with 1-cm graduation markers was passed into the jugular vein. B-mode and color flow pictures were captured at aortic branches in cross and longitudinal sections. Length measurements between aortic branches and Doppler spectral velocities were obtained. Guidewire, balloon, and stent maneuvers were monitored by the stationary intravenous IVUS probe.

RESULTS

High-quality visualization of the entire abdominal aorta and its branches was achieved in all animals. With the probe stationary in the vena cava, a 1.5-cm linear segment of the aorta could be continuously observed in both B-mode and color flow ultrasound scans. Insertion and implantation of a Palmaz balloon-expandable stent was guided by intravenous IVUS alone. Selective catheterization of the right renal artery was followed visually by moving the intravenous IVUS probe sequentially.

CONCLUSIONS

Intravenous IVUS appears feasible as a guidance and monitoring tool for endovascular interventions. While conventional IVUS provides only cross-sectional images in B-mode, intravenous IVUS captures color flow and Doppler velocity data as well. These added ultrasound modalities may offer potential advantages for guidance of endovascular procedures and endoleak detection.

Prediction of outcome after femoropopliteal balloon angioplasty by intravascular ultrasound

OBJECTIVE

To evaluate intravascular ultrasound (IVUS) as a control procedure after femoropopliteal percutaneous transluminal angioplasty (PTA), and compare it with arteriography.

DESIGN

Descriptive study.

MATERIAL

Arteriographic and intravascular ultrasound data obtained from 18 patients (20 limbs) undergoing PTA of the superficial femoral or popliteal artery. The degree of stenosis, the diameter and area of the lumen and the morphological changes in the plaque were related to the short-term patency of the intervention, as evaluated by duplex scan and ankle branchial index.

RESULTS

Fifteen arteries remained patent. Two occlusions and two stenoses developed during the first 3 months after the intervention and one occlusion occurred after 1 year. The following IVUS parameters were related to a favourable patency: presence of calcification; dissection or plaque rupture and residual stenosis of less than 70%. The arteriographically determined diameter reduction did not show predictive value.

CONCLUSION

This study shows that in contrast to arteriography, IVUS revealed parameters predictive for patency following PTA.

Intravenous intravascular ultrasound for arterial visualization: a feasibility study

PURPOSE

The advent of endovascular grafting has created detailed imaging requirements for which intravascular ultrasound (IVUS) may be useful. Since intra-arterial IVUS imaging uses space within endovascular graft delivery systems and risks embolism, we investigated the use of intravenous IVUS imaging of arterial vasculature and endovascular grafts, a technique that appears not to have been previously described.

METHODS

IVUS catheters with 12.5- and 20-MHz transducers were inserted through the common femoral artery and vein of mature sheep. Transcutaneous images were also obtained with a 5-MHz linear transducer. B-mode images of the aortoiliac arterial segments and diameter measurements were recorded from both access vessels using anatomic landmarks for site localization. To assess device visualization from the intravenous image source, studies were done in vessels containing previously placed endovascular stent-grafts.

RESULTS

In this feasibility study, comparison among intravenous IVUS, arterial IVUS, and external ultrasound indicated equal diameter precision and ability to recognize arterial structures. Comparison of arterial diameter, whether obtained from an arterial, venous, or transcutaneous source, showed similar values.

CONCLUSIONS

We conclude that it is probable for such techniques to be usefully applied to human aortoiliac arterial segments and that further investigation of arterial visualization from adjacent venous structures is warranted.

Intravascular ultrasonography

Intravascular ultrasonography is developing rapidly as a method for defining the transmural anatomy of vascular structures, with diagnostic and therapeutic applications. The ultrasound technology not only has unique diagnostic capabilities by defining the distribution and character of lesions, but also provides accurate control information regarding efficacy of angioplasty methods. An exciting recent development is the three-dimensional reconstruction of two-dimensional images which permits global examination of luminal and transmural vessel morphology. This technology may enable improved guidance of intraluminal devices to enhance lesion removal without damaging adjacent normal wall structure and appropriate device selection by differentiating specific plaque characteristics.

Sequential intraluminal ultrasound evaluation of balloon angioplasty of an iliac artery lesion

This report describes intravascular ultrasound imaging of a localized 81% stenosis in the left common iliac artery of a 52-year-old woman. The lesion was dilated using an 8 mm balloon and was imaged pre- and post-dilation using arteriography and a 5F, 30 Mhz intravascular ultrasound catheter. The same site was imaged again intraoperatively at two months following the initial procedure using an 8F, 20 Mhz intravascular ultrasound catheter when the patient had a femoropopliteal bypass for continuing ischemia. Intravascular ultrasound imaging allowed accurate, sequential, on-line calculation of the cross-sectional area and volume of the lesion both, acutely and following healing of the site. The morphology of the fractured arterial plaque was clearly defined, demonstrating distribution of calcification, and intraluminal flaps not apparent on arteriography. The case demonstrates the unique potential of intravascular ultrasound in assessing the immediate effect of interventions and evaluating the long-term healing.

Stenosis following laser thermal angioplasty--a blinded controlled randomized study between aspirin against Probucol

Long-term patency of vascular angioplasties is limited by stenosis from neointimal hyperplasia or progressive arteriosclerosis. This study evaluated the hypothesis that ASA (an antiprostaglandin) or Probucol (an antioxidant) may be useful in preventing stenosis following laser thermal angioplasty. Aortoiliac arteriosclerosis was induced in 17 female New Zealand white rabbits with a combination of endothelial denudation (4 Fr. Fogarty balloon catheters) and 2% cholesterol-supplemented diet for 6 weeks. All rabbits then underwent arteriography and were immediately randomized to one of three groups: Group I (n = 6), control, laser but no adjunctive therapy; Group II (n = 5), laser and ASA 10 mg/kg/day; Group III (n = 6), laser and 1% Probucol diet. Retrograde laser thermal angioplasty was performed with a 1-mm coronary Laserprobe. Six watts of argon laser energy was delivered for a single 5-sec pulse using a continuous motion from the right common iliac artery to the aorta. Pre- and postlaser arteriography was performed in all groups. Rabbits were sacrificed 1 month following laser angioplasty, and aortoiliac sections were taken after in situ perfusion fixation with paraformaldehyde and 0.05% glutaraldehyde. Serial 5-mm segments, proximal to the aortic bifurcation and distally from the same, were taken, stained, and evaluated by quantitative morphometry. From each segment, lesion area and lesion area/internal elastic laminae area were evaluated and compared. Serum cholesterol increased from 60.8 +/- 19.5 to 1494.7 +/- 12.7 mg% following institution of the cholesterol diet (P less than 0.05). Arteriosclerotic lesions were observed in all rabbits and maximally located around the common iliac artery.(ABSTRACT TRUNCATED AT 250 WORDS)