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Ann Thorac Surg 2005;79:2013-2017
© 2005 The Society of Thoracic Surgeons

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Original article: Cardiovascular

Optimizing Saphenous Vein Site Selection Using Intraoperative Venous Duplex Ultrasound Scanning

Department of Surgery, Sutter Medical Center of Santa Rosa, Santa Rosa, California

Accepted for publication December 20, 2004.

^_* Address reprint requests to Dr Cohn, 5773 Shiloh Ridge, Santa Rosa, CA95403 (E-mail: jcohn{at}alum.mit.edu).

	Abstract

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
BACKGROUND: Saphenous vein is the most common conduit utilized for coronary artery bypass. However, preoperative noninvasive venous studies to evaluate saphenous vein morphology are not commonly performed due to limited logistical support. A prospective, nonrandomized study was developed to assess the utility of intraoperative saphenous vein duplex ultrasound studies in optimizing saphenous vein site selection.

METHODS: Intraoperative saphenous vein duplex scanning was performed in 58 consecutive patients undergoing coronary artery bypass surgery utilizing two-dimensional ultrasound monitoring equipment. Following anesthetic intubation, studies were performed by one of the surgeons. Most scans were completed in less than 8 minutes.

RESULTS: Findings demonstrate at least 1 venous abnormality in 31 of 116 (26.7%) above knee saphenous veins and 59 of 116 (50.9%) below knee veins. In 38 of 58 patients (65.5%), duplex ultrasound scanning proved beneficial in surgical site selection. Most abnormalities are related to major branches and bifurcations except in the lower calf where small lumen caliber is the most common abnormal finding. Additional beneficial findings include identifying abnormal vein course, identifying suitable conduit in reoperative procedures and precise localization of vein segments for endoscopic surgery.

CONCLUSIONS: Intraoperative saphenous vein duplex scanning is rapidly and easily accomplished with available operating room resources. Study information allows optimal surgical site selection, avoiding unnecessary surgical dissection, time delays, vein wastage and potential for wound complications. Optimizing incision site selection eliminates blind exploration for vein conduit, improves conduit planning, and expedites surgical dissection during endoscopic vein harvest.

	Introduction

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Saphenous vein is the most common coronary artery bypass (CAB) conduit. Although clinical examination of the distal calf may suggest a satisfactory origin of the great saphenous vein, morphologic assessment of proximal segments remains unknown until surgical exploration. Benefits of preoperative saphenous vein mapping have been documented for peripheral vascular reconstructive procedures [1–3] and for assessment of coronary artery conduits [4, 5]. Complications of saphenous vein harvest include leg wound infections [6] and ischemic ulcers [7], and pose an increased risk in elderly patients with associated peripheral vascular compromise. Postoperative surgical site infection in a limb that does not provide a satisfactory venous conduit is frustrating, may lead to increased limb complications, and is a potentially preventable event [3, 5]. Use of vein mapping provides a means to accurately identify venous abnormalities. With precise knowledge of vein anatomy, direct incision over the vein segment may be performed, which eliminates extensive dissection and avoids development of skin flaps and hematoma. However, the standard noninvasive venous ultrasound procedure is time consuming and requires access to a noninvasive vascular laboratory with vascular technologist support personnel. Logistical support and scheduling coordination is often difficult because vein mapping requires skin marking and must be performed within a few days before surgery. In urgent or emergent circumstances, where knowledge of saphenous vein morphology would be most useful, vein mapping is not likely to be performed.

Ultrasound studies have demonstrated saphenous vein abnormalities in more then 30% of limbs [8]. Ideally, identification of distended saphenous vein segments utilizing ultrasound scanning should be performed in all patients. Knowledge of small caliber vein segments, abnormal vein course, bifurcated vein segments, multiple vein branches, and thrombosed or dilated vein segments could then be used to plan incision sites for saphenous vein access and avoid needless, fruitless, and time consuming surgical dissection.

	Material and Methods

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This prospective, nonrandomized, preliminary study was performed to define the utility of intraoperative duplex venous ultrasound studies to optimize saphenous vein harvesting during CAB surgery. The study consists of 58 consecutive patients undergoing CAB surgery and associated procedures. Studies were performed in elective and emergent cases. Intraoperative ultrasound venous studies are performed following endotracheal intubation and bladder catheterization with a high-resolution real-time duplex scanner (Acuson Sequoia 512 Ultrasound System; Acuson Corp, Mountain View, CA) and model 15L8 linear array probe. This probe is also utilized to assist in locating jugular veins and radial arteries, if difficulty is encountered during upper extremity vascular access. It is occasionally used to assess ascending aorta plaque and calcification prior to aortic arch cannulation. The same ultrasound equipment provides for routine intraoperative two-dimensional echocardiographic monitoring, with a TE-V5Ms (Acuson Corp, Mountain View, CA) multiplane transesophageal probe.

Following endotracheal intubation, a tourniquet is placed around the proximal thigh using a 1-inch Penrose drain secured tightly with a Kelly clamp to occlude the saphenous vein distal to the saphenofemoral junction. The low profile tourniquet allows scanning to be performed to the proximal thigh. Venous distension approximates the distension achieved during vein conduit preparation. All studies are performed by one of the operating surgeons. Real-time transverse axial scanning provides sufficient imaging to assess venous anatomy. Scans are performed with ultrasound transmission gel (Aquasonic 100; Parker Laboratories, Inc, Fairfield, NJ), from the ankle to the proximal thigh, with the leg externally rotated and the knee flexed. Initial ultrasound depth adjustment is 30 mm with 10.0-MHz probe scan frequency. Increased depth setting is necessary in large or obese limbs. Additional probe frequencies of 8.0, 11.5, and 13.0 MHz are also available. The rectilinear scan image facilitates morphologic interpretation and estimates of internal lumen dimensions. Vein tracking is rapidly performed along the course of the saphenous vein. Veins in obese limbs are readily identified. Skin marking is performed with indelible ink [9] (Pilot Super Color Marker B; Pilot Corp of America, Trumbull, CT). Location of the vein at the medial knee is identified and marked for dissection during endoscopic vein harvest. Frequent tissue pressure with the scan head is used to compress the saphenous vein in order to identify areas of venous thrombosis. Venous abnormalities and internal lumen diameters of the distended vein segments are recorded. Vein depth is noted in large or obese limbs. Scan time for each leg is usually 3 to 4 minutes. Normal studies are completed in less time. Additional scan time is necessary if the great saphenous vein is unsatisfactory and accessory saphenous vein segments require identification as conduit options.

Patient data includes age, gender, type of surgery, ankle/brachial artery pressure index, presence of lower extremity varicosities, and history of stripping or ligation of lower extremity varicose veins. Saphenous vein segments were evaluated in the proximal and distal calf and thigh, reflecting the use of each of these vein segments at these sites as coronary conduits. Vein segments were considered normal if they were continuous and measured 2-mm to 5-mm internal diameter, with progressive increase in size proximally. A vein segment less than 2-mm internal diameter was considered small and unlikely to be considered for conduit use. A discontinuous segment was identified if there was a major branch or abnormality affecting lumen size of the great saphenous vein or if a major bifurcation was evident. Dilated vein segments were identified as veins greater than 5-mm internal diameter or with major focal dilatations. All vessels demonstrated normal compression on probe pressure. No thrombosed vein segments were detected. On occasion, more then one abnormality was present within a vein segment.

Following each study, the benefit of the intraoperative ultrasound examination was recorded. An ultrasound study was considered a beneficial aid if the study directed vein harvesting away from abnormal vein segments. A benefit was also noted in endoscopic vein site selection in large or obese limbs where the vein was identified more than 35 mm from the skin surface and in a few additional isolated and unusual cases.

Examples of characteristic imaging studies are shown in Figure 1. Statistical analysis of categorical data was performed by the Chi-square method.

View larger version (52K): [in this window] [in a new window]   Fig 1. (A) Transaxial scan distal calf revealing 1.6-mm internal diameter great saphenous vein (arrowhead). (B) Scan image midcalf demonstrating great saphenous vein with major branch (two arrowheads). Largest vein measures 3.2-mm internal lumen diameter. (C) Scan image distal thigh illustrating great saphenous vein (arrowhead). Internal lumen diameter measures 3 mm. Vertical axes, all panels, 20-mm full scale.

	Results

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

Tabulation of vein morphology is recorded in Table 1. An abnormal event was recorded if the ultrasound scan demonstrated the abnormality to include a sufficient portion of the proximal or distal calf or thigh vein segment to preclude its use as a vein conduit. Eight venous segments were evaluated in each patient. A total of 464 venous segments were examined in the 58 patients studied. A total of 183 abnormalities were identified. Discontinuous segments were most common (59.6%) followed by small vessel segments (38.3%) and dilated vessels (2.2%). Abnormal venous morphology is most common in the proximal calf where 42.6% of all abnormalities were detected. The next most common site is the lower calf. Proximal thigh segments accounted for 13.7% of abnormalities and distal thigh segments contributed to 16.9% of all abnormalities. Of the 116 complete limbs examined, 45 (38.8%) were normal.

Utilization of intraoperative lower extremity venous ultrasound proved beneficial in 38 of 58 patients (65.5%), by identifying major areas of discontinuity, attenuated vein segments, depth and location of veins in obese limbs, and abnormal vein locations. Selective incisions were placed to avoid needless dissection and reduce vein harvest time delays. On occasions, small calf veins (2-mm internal diameter) were harvested. During vein preparation these veins distended sufficiently to be usable as a coronary conduit where a small diameter conduit to coronary artery match was suitable. In most cases, small-sized veins were not acceptable. As limb dissection of small vein segments was usually avoided, the decision process for utilizing small caliber saphenous vein segments as coronary artery conduits remains uncertain [5].

While not systematically investigated, use of intraoperative duplex scanning has proven useful in patients undergoing reoperative CAB surgery. Venous ultrasound studies in 1 patient demonstrated an overlooked great saphenous vein segment or an enlarged bifurcated vein segment, adjacent to an incision site that was suitable for use as a venous conduit.

The incidence of fruitless attempts at vein harvesting may be estimated from analysis of the data in Table 2. If the right lower extremity is routinely utilized for saphenous vein harvesting then at least one significant venous abnormality would be encountered in 17 of 58 thigh segments (29.3%) and 26 of 58 calf segments (44.8%). This calculation possibly overestimates the incidence of unsuitable harvested vein segments because a portion of a harvested vein containing some abnormality may be salvageable for conduit use.

	Comment

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

Patient position and techniques during ultrasound examinations have included 10-degree to 20-degree reversed Trendelenburg position without tourniquet [1, 4, 5]. Hoballah and colleagues [13] studied the effect of tourniquet application and position on saphenous venous distension in normal male volunteers. Maximum vein diameters were achieved with dependency and 40 mm Hg tourniquet inflation. Saphenous vein diameters, with tourniquet and reversed Trendelenburg position, increased 0.39 mm above the knee and 0.15 mm below the knee compared to dimensions recorded during supine position with tourniquet. The increase in vein caliber with increased venous pressure associated with reversed Trendelenburg position suggests that vein internal lumen dimension may be further increased following conduit preparation with directly applied fluid distension.

Use of intraoperative ultrasound venous duplex scanning provides a safe and rapid means to assess saphenous vein morphology. Proximal thigh tourniquet application results in prompt distension of the saphenous vein and allows measurements of internal lumen dimensions. Ultrasound equipment utilized in this procedure is also utilized for intraoperative two-dimensional echocardiographic monitoring of myocardial function. A portable gray-scale ultrasound monitor or use of a sterile sheath over the scan probe would be other options to aid in intraoperative assessment of the saphenous vein.

Data analysis demonstrates normal studies in 85 of 116 thigh veins (73.3%) and 57 of 116 calf veins (49.1%). Discontinuities represented the major abnormality in all segments except for the lower calf segment where small caliber veins were the most common abnormal finding. In 50 instances, more than one venous abnormality was present within a vein segment. Almost all of these were related to the association of discontinuities and small caliber veins.

Isolated abnormal findings affecting site selection include a thigh segment vein dilatation, venous valve dilatation and a large posterior thigh vein arising from the short saphenous system with absence of the normally positioned great saphenous vein. Reoperations occurred in 3 patients. In one patient undergoing reoperative CAB, duplex scanning demonstrated a satisfactory vein segment adjacent to a previous surgical vein excision site. A similar finding was reported by Head and Brown [5]. In the two other patients, the remaining saphenous venous systems were normal.

Findings in intraoperative ultrasound examinations provide a means to plan conduit options while limiting surgical incisions and avoiding vein waste. Other reports have demonstrated correlation of preoperative vein mapping with operative findings [3, 5, 6], and suggested a reduction in wound complications and infections attributable to surgical site selection. Allen and Shaar [14] utilized a portable intraoperative two-dimensional ultrasound system to locate the saphenous vein prior to endoscopic vein harvest. They documented a decrease in time required for identification and dissection of the saphenous vein, especially in obese patients.

Intraoperative duplex ultrasound scanning proved beneficial in surgical site selection in 38 of 58 patients (65.5%). In the majority of cases, branched vessels, bifurcations, and small caliber veins were avoided and the better-quality limb was selected. In isolated instances, surgery was averted on limbs with major venous anatomic abnormalities. In obese patients, vein position and depth information proved valuable in surgical site incision placement before endoscopic vein harvest. Routinely, intraoperative ultrasound scan led to optimum endoscopic incision site selection and to the optimum sites for excisional vein harvesting. The unexpected high incidence of benefit utilizing intraoperative ultrasound likely relates to the greater use of saphenous vein as the conduit of choice and limited use of internal mammary artery in an older age population.

Conclusions
Intraoperative venous duplex ultrasound study of the great saphenous veins with use of tourniquet is quickly and easily performed during intraoperative preparatory procedures. The study provides information related to venous abnormalities and distended vein lumen caliber. Intraoperative ultrasound scanning eliminates failed attempts at endoscopic or excisional vein harvesting in a calf or thigh with a small caliber vein, vein branches, dilatations or bifurcations. Precise incision site selection is identified for endoscopic vein harvesting. Optimal surgical vein excision site selection is achieved by avoiding incisions over abnormal vein segments.

	Acknowledgments

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
The authors thank James C. Finn, MD, cardiac anesthesiologist, for suggesting use of the small body part ultrasound probe and monitoring scanner for intraoperative venous duplex ultrasound scanning. We thank him for his assistance in integrating and coordinating postintubation preparatory procedures. The authors thank him and Peter Anastassiou, MD, for manuscript review.

	References

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Joseph D. Cohn Keith F. Korver Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cohn, J. D. Articles by Korver, K. F. Search for Related Content PubMed PubMed Citation Articles by Cohn, J. D. Articles by Korver, K. F. Related Collections Coronary disease