A method of performing descending venography

Transcription

1 A method of performing descending venography Robert L. Kistner, M.D., Eugene B. Ferris, M.D., Gurinder Randhawa, M.D., and Curtis Kamida, M.D., Honolulu, Hawaii With the recent development of successful methods to correct valve incompetence in the lower extremity, there is a need for a standardized approach to descending venography. This is the single test that accurately defines the site of the venous valve and demonstrates its competence or degree of incompetence. This report describes a technique of descending venography, including the details of catheter placement, injection procedure, and monitoring techniques. Interpretation of the study requires a method that analyzes both the individual valve function and the overall valvular competence of the entire extremity. Descending venography can separate patients with primary valve incompetence from those with postthrombotic valve destruction, as well as the occasional case of valve aplasia. Points on interpretation of valve function and the use of the Valsalva maneuver for "stressing" the valve are discussed. The descending venographic results are compared with the clinical state and with venous pressure findings in 78 extremities. (J VASC SURG 1986; 4:464-8.) The demonstration that surgical procedures can be successfully carried out to repair or replace valves in the deep venous system has created a practical need for knowledge of the exact location and function of the valves in the deep venous sytem. Descending venography shows exactly where the valve stations exist in the common (CFV), superficial (SFV), and profunda femoral (PFV) veins and in the greater saphenous vein (GSV). The Valsalva maneuver is used to determine the true functional capacity of the valve. Descending venography is the definitive test for the differential diagnosis between primary valve incompetence (PVI), postthrombotic (secondary) valve incompetence (SVI), and valve aplasia in patients with an incompetent deep venous system.~ This article describes the details of the technique used at the Straub Clinic for performing descending venography. METHOD Descending venography is best done with the patient in a semierect position, with a Valsalva maneuver used to demonstrate the functional integrity of the valve. Dynamic filming by way of fluoroscopy is essential to demonstrate the function of individual valves. It is helpful to record the procedure on vi- From the Section of Peripheral Vascular Surgery (Drs. Kistner, Ferris, and Randhawa) and the Department of Radiology. (Dr. Kamida), Straub Clinic & Hospital, Inc. Presented at the First Annual Meeting of the Western Vascular Society, Laguna Niguel, Calif., Jan , Reprint requests: Robert L. Kistner, M.D., Section of Peripheral Vascular Surgery, Straub Clinic & Hospital, 888 S. King St., Honolulu, HI deotape for subsequent study and for a perman,.~nt record of the dynamics of flow. Catheter placement The procedure can bc done by way of a percutancous catheter introduced into the CFV and positioned in the proximal CFV or by way of a catheter passed from the arm and guided down the superior and inferior vena cava into the CFV. The findings by either method are similar in our experience. The advantage of passing a catheter from the arm is to catheterize the branches of the CFV individually; the advantage of percutaneous puncture of the CFV is that it is simpler and quicker. Introduction of arm catheter. The patient is placed supine on the x-ray table and with the Setdinger technique, a long catheter is introduced via the antecubital vein through the basilic vein and guided through the vena cava to the CFV on either side. The table is then brought to a 60-degree tilt in the foot-down position so that the patient is semierect. Initial injections are carried out with the catheter in the CFV, and after this, the catheter can be used to select the branches of the CFV, depending on the area of interest. Introduction of catheter via femoral veins. With the patient in the supine position, percutaneous puncture is used to place a short catheter into the CFV with the tip directed centrally. With fluoroscopic guidance the catheter is situated in the high CFV at about the upper level of the femoral head. With the patient in the supine position, contrast medium is introduced to study the anatomy of the iliac

2 Volume 4 Number 5 November 1986 Descending venography 465 vein and inferior vena cava. The table is then turned to the 60-degree foot-down position and the study of the veins is begun with introduction of contrast material into the CFV and monitored with fluoroscopy. Injection procedure The injection technique involves a slow, steady hand injection of contrast medium (200 ml or more) under fluoroscopic monitoring. We have the patient bear weight on a block placed under the contralateral foot so that the extremity being studied is relaxed and non-weight-bearing. With the catheter in the CFV and the patient in the semierect position with the table at a 60-degree foot-down tilt, contrast medium is injected while the patient breathes normally. The operator observes whether the contrast material flows proximally toward the heart, settles into a valve cusp, or refluxes down the leg. When contrast material refluxes distally, one may see valve stations in the CFV, PFV, SFV, and GSV. If the proximal valve is competent and closed, distal valves will not be visualized. In this manner, the operator learns where the valves are located in the SFV, PFV, and GSV. Armed with knowledge of valve location, the filming is repeated by injection of contrast medium while the patient performs a sustained Valsalva maneuver and the previously identified valves in the SFV, GSV, and PFV are observed under stress. It is advisable to teach the patient to do a sustained Valsalva maneuver before the procedure to ensure a good study. The flow of contrast material is defined separately in the SFV, PFV, and GSV. In each instance, the sites of the valve stations are noted and the function of each valve is tested under both quiet breathing and Valsalva conditions. If the contrast medium refluxes in any of these branches, the distal extent of flow is noted. During the procedure, radiographs are obtained to demonstrate key findings. The dynamics of flow are recorded on a videotape. An audio record on the videotape to indicate the position of the patient at the time of injection and whether the patient was performing a Valsalva maneuver at the time of filming allows accurate interpretation of the tape when it is reviewed later. Interpretation of the descending venogram Since the density of the contrast agent is much greater than that of blood, one can observe the heavier contrast agent settle into the valve cusps of a slowly flowing or static column of blood under fluoroscopic monitoring. The normally functioning valve is open most of the time to allow blood to flow toward the heart, but it is capable of closing completely under stress and it prevents all leakage when in the closed position. To find out whether a venous valve is a normally functioning valve, it is necessary to test it under stress conditions, as by the use of a sustained Valsalva maneuver. When a person exerts a strong Valsalva maneuver, intra-abdominal pressure increases and the venous flow is slowed, stopped, or forced retrograde. This resistance to prograde flow exerts pressure distally and causes the valve cusps to close. The mechanism of valve closure involves apposition of the two valve leaflets in the midline. The harder one pushes against a competent valve, the tighter the valve closure becomes while the harder one pushes against an incompetent valve, the greater the degree of reflux. This is the crux of the differential diagnosis of the competent as opposed to the incompetent valve. The findings of descending venography are classified according to the function of the individual valve and according to the degree of reflux in the entire extremity. Spectrum of individual valve function Normal valve. The normal valvc closes completely when faced with proximal resistance, as in the Valsalva maneuver, and there is absolutely no leakage through it. No matter how hard the patient pushes against the valve, leakage does not appear. Minimal leakage. Many valves are seen in which a wisp of contrast medium refluxes through the valve under a forced Valsalva maneuver. This is an easily acceptable degree of leakage that has no physiologic importance. Moderate leakage. In these valves, the Valsalva maneuver causes a definite flow of contrast material distally through the valve. It is easily seen on the screen as the contrast agent enters the valve cusp and then flows distally through the valve. There are degrees of leakage in this category that are difficult to distinguish in a quantitative sense. Severe leakage. When the leakage is most severe, there is a cascading appearance of contrast medium flowing retrograde through the valve. It literally pours through the valve cusps. Extent of reflux In estimating the severity of leakage, it is important to note how far distally the reflux extends. This is most important in the SFV where clinically serious

3 466 Kistner et al. JOLll'llal Of" VASCULAR SURGERY Fig. 1. Descending venograms demonstrate spectrum of valve function. In each case contrast material is injected in the common femoral vein. Grade 0, normal superficial femoral vein (SFV) valve, 100% competent; grade 1, wisp of reflux down medial wall of SFV for short distance; grade 2, reflux in SFV to mid or distal thigh with competent valve at this level;grade 3, reflux throughout SFV and popliteal vein into Calf veins; and grade 4, cascading reflux throughout thigh, knee, and calf. leakage is thought to be that which extends all the way into the calf; it may even pass out through incompetent calf perforators. When the reflux does not extend into the calf because a competent valve can be identified in the distal SFV or the popliteal vein, we believe the reflux is not of major clinical importance. When reflux is evaluated in the PFV, those cases that show distal communication between the PFV and the popliteal vein through large branches in the distal thigh are classified as clinically important degrees of reflux. When the reflux is limited to the thigh, it is of less significance. In.the iliac vein, contrast material should flow centrally toward the heart during quiet breathing. Cardiad flow will usually be seen even during the Valsalva maneuver in patients who have competent femoral valves. When there is severe reflux, proximal flow will totally cease during the Valsalva maneuver, and it may not even be visible in the erect position during quiet breathing, Classification of overall reflux The classification of overall reflux in the extremi W that we follow includes two elements, the amount of leakage through the valves and the distal extent of the leakage in each vein segment, the SFV, PFV, and GSV (Fig. 1). These are combined in the following manner: Normal valves: No reflux occurs through any valve during the Valsalva maneuver. These patients show continuous centrad flow in the iliac vein even during the Valsalva. 1 + Abnormal: Wisp of reflux through one or more valves during Valsalva maneuver. The amount of reflux is seen to be trivial and prograde iliac flow is maintained. 2+ Abnormal: Considerable reflux is seen through the valves in the thigh, but a competent valve is present in the distal thigh on the popliteal vein and none of the reflux passes into the calf. Some progradc flow is retained in the iliac vein in most of thesc cases. 3 + Abnormal: Considerable reflux is seen, similar to the finding in the 2 + catego~, but the leakage passes through the popliteal vein into the calf. Prograde flow may or may not be seen in the lilac vein. 4 + Abnormal: Cascading reflux extends from the femoral veins through the thigh and into the calf. There is no prograde iliac vein flow. This type of reflux is visually impressive and is unmistakable. DISCUSSION Descending venography was begun in the early 1940s by Gunnar Bauer 2 in Sweden who first described the occurrence of leaking valves in the deep veins, the syndrome we now call PVI. Other authors in Sweden, England, and Canada studied descending venography and obtained conflicting findings of its usefulness? -H The two key differences between these

4 Volume 4 Number g November 1986 Descendir(t~ venography 467 Table I. Overall valve function Catego~ 0-1 Catet~ory 2 Catego~. 3-4 Clinical status (No. of limbs) (No. of limbs) (No. of limbs) Total Normal Ache/swell Ulcer/induration Total NOTE: Clinical categories describe the primary problem in a given extremity. earlier reports and the present method that render the new method reliable and reproducible are that the proccdure is now done with fluoroscopic imaging rather than with still radiographs, which allows direct visualization of the dynamic events of flow; and the valvc function is tested under stress by having the semicrect patient exert a forced Valsalva maneuver. The findings of descending vcnography have not bccn consistent and reproduciblc in our cxpcricncc until this method was standardized. Notes on interpretation. Many instances will bc sccn where contrast medium settles through open valves during quiet breathing but when a Valsalva mancuvcr is done, the valve leaflets can bc obscrvcd to snap shut and valve reflux immediately ceases. We bclicvc this occurs because the leaflets arc lying in the open position to allow progradc flow during quiet breathing, but whcn the Valsalva maneuver is begun, the leaflets snap shut. This valvc is considered to be a normal valve. Other valves seem to be competent during quiet breathing, but important degrees of leakage occur with the Valvalsa maneuver. These are thought to be abnormal valves that cannot withstand a pressure load, and it requires a Valsalva maneuver to identi~ the dysfunction of the valve. Postthrombotic valve destruction. In veins in which previous thrombosis has existed, the valves are scarred and shortened and the vein lumen is occupied by varying amounts of intraluminal septae. Since there are no valves, all of these recanalized veins will be incompetent. The degree of incompetence will vary, depending on the amount ofintraluminal septae that are present. When the vein lumen is quite full ofseptae left over from the previous thrombus, reflux will not be massive; when the vein lumen is virtually clear of septae and recanalization is complete, the reflux resembles a case of valve aplasia. The Straub experience. Descending venography was first done at Straub Clinic in 1968; since then more than 200 cases have been performed. Normal legs have been studied, usually as the contralateral side in a patient who has symptoms in one leg, to provide the normal end of the spectrum of valve function. All of the patients have had Doppler study of the veins and most have had venous pressure determination. More recently, volumetric studies of venous outflow have been added. All cases have had ascending venograms done before the descending venogram. Our findings comparing the accuracy of the Doppler examination with descending venography are that the Doppler study is an excellent screening device, which helps in selecting patients for the definitive descending venography test. The limitations of the Doppler examination are that it does not identify accurately which segments are incompetent, it does not tell where the valve stations are located, it does not distinguish PVI from postthrombotic venous incompetence, and it is not quantitative. In 78 cases the clinical state was classified and compared with the descending venographic findings (Table I). Those patients with a severe clinical syndrome show severely abnormal descending venograms in 72% (23 of 32 cases), and only three of these extremities had a completely normal descending venogram. Those patients who had normal legs studied by descending venography showed a normal or mildly abnormal venogram in 92% (12 of 13 cases). The venous pressure studies did not correlate as well with descending venography as did the clinical state, although the overall correlation was positive. The finding that there are cases in which the venous pressure studies do not reflect the clinical state has been well documented by previous studies? 2 We conclude from the comparison of these studies that the accurate interpretation of the venous state in a given case requires clinical evaluation, physiologic testing by pressure or volumetric data, and accurate venographic study. In this context, descending venography is accurate in defining the anatomy and function of the valves at the femoral level and below when done by the technique outlined herein.

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