FIGURE 2. Excised stenotic bicuspid aortic valves from the 4 patients are shown from left to right. Valve no. 4 bad a large per- foration that was blocked by an area of calcium from the opposite leaflet.

1. Roberts WC. The congenitally bicuspid aortic valve. A study of 85 autopsy cases. Am J Cardiol 1970;26:72-83. 2. Wanda NC, Gramiak R, Shaw PM, Stewart S, DeWeesc JA. Echocardiogra- phy in the diagnosis of idiopathic hypertrophic subaortic stenosis co-existing with aortic valve disease. Circulation 1974;50:752-751. 3. Stewart S, Nanda N, DeWeese J. Simultaneous operative correction of aortic valve stenosis and idiopathic hypertrophic subaortic stenosis. Circulation 1975; 51/52(suppl 1):1-34-I-39.

rl. Feize 0, Farrer-Brown G, Emanuel R. b’amilial study of hypertrophic cardio- myopathy and congenital aortic valve disease. Am J Cardiol 1978;41:956- 964. 5. Parker D, Kaplan MA, Connolly JE. Coexistent aortic valvular and functional hypcrtt-ophic subaortic stenosis. Am J Cardiol 1969;24:307-317. 6. Panza JA, Maron BJ. Valvular aortic stenosis and asymmetric septal hypertro- phy; diagnostic consideration and clinical and therapeutic implication. Eur Hem J 1988;9(suppl E):71&76.

Experience with the Gianturco==Roehm Bird’s ava Filter Bryan Martin, DO, Thomas E. Martyak, MD, Thomas L. Stoughton, MD, William A. Collazo, MD, and William Pearl, MD

M echanical interruption of the inferior vena cava pro- tects patients with lower extremity deep venous

thrombosis from pulmonary embolism. It is the proce- dure of choice for patients who either cannot be antico- agulated, or have had recurrent pulmonary embolism despite anticoagulation. Extensive experience with the Greenfield vena cava filter (Medi-tech Inc., Watertown, Massachusetts) has shown long-term caval patency rates of >95%, and rates of recurrent pulmonary embolism of <5%.r However, a malposition rate as high as 14%,2,3 premature filter release,4 perforation of the inferior vena cava and associated structureq5 and femoral vein throm- bosis at the site of insertion6 remain potential problems.

The Gianturco-Roehm Bird’s Nest Filter (Cook Inc., loomington, Indiana), approved for clinical use by the

Food and Drug Administration in 1989, was designed to

From the Department of Medicine, Cardiology Service, William Bcau- mont Army Medical Center, El Paso, Texas; and Pratt Medical Center, 1701 Fall Hill Road, Fredericksburg, Virginia 22401. The opinions or assertions contained herein are the private views of the authors and should not be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. Manuscript received April 2, 1990; revised manuscript received and accepted June 26, 1990.

-i-HE AMERICAN JOURNAL OF CARDIOLOGY NOVEMBER 15, 1990

F IGURE 2. The fine wire mesh filter occupies a 6- to I-cm k mgth of inferior vena cava.

overcome some of the disadvantages of the Greenfield filter. Designed for percutaneous introduction through the jugular, subclavian and femoral approaches, it con- sists of 2 rigid, V-shaped struts, between which are at- tached four 25cm-long, 0.18-mm diameter stainless steel wires (Figure 1). Properly positioned, the fine wire mesh filter occupies a 6- to 7-cm length of inferior vena cava (Figure 2).

From December 1989 to March 1990, 5 patients, 3 men and 2 women aged 32 to 81 years, underwent Bird’s Nest filter placement by the femoral approach at our facility. All had malignancies with pulmonary embolism or deep venous thrombosis, and contraindications to or failure of anticoagulation.

The Bird’s Nest filter delivery system consists of a l2Fr sheath designed for insertion over a 0.038-inch guidewire, and an 1lFr filter-carrying catheter.7 The catheter contains the jilter, an attached pusher wire for filter advancement and release, and a sidearm allowing injection of contrast distally to facilitate filter position- ing. After obtaining venous access percutaneously, vena cavography is performed to assess the presence of thrombus, size of the inferior vena cava and renal vein locations, The distal ends of the sheath andfilter-carry- ing catheter are positioned just below the renal veins, usually located near the LI -L2 vertebral interspace. While holding the pusher wire stable, the catheter/ sheath assembly is withdrawn to expose the distalfilter strut while maintaining its junction point just inside the catheter. Gentle advancement of the catheter/sheath as- sembly I to 3 mm secures the strut and its anchoring hooks in the wall of the inferior vena cava. The catheter/

TABLE I Characteristics and Complications of Greenfield

and Bird’s Nest Filters7,10

Greenfield Bird’s Nest Filter Filter

Length (mm) 41 70 Diameter (mm) 30 54 Carrier size (Fr) 24 11 Maximal caval diameter (mm) 30 40 Recurrent pulmonary 5 3

embolism (%) Caval patency (%) 95 97 Femoral vein thrombosis (%) <15 unreported Migration (%) uncommon 0’ Vascular perforation uncommon Rare

i* Food and Drug Administration approved second-generation device with rigid struts.

sheath assembly is then withdrawn an additional 1 to 3 cm over the stationary pusher wire to release the distal strut from the catheter. This maneuver permits passage of the filter wires by further advancement of the pusher wire, and provides room for filter formation within the inferior vena cava. TheJilter catheter/sheath assembly is then advanced so that the junction point of the proximal strut, which still remains in the catheter, overlaps the junction point of the distal strut by I to 2 cm, thus packing the loops of wire in the inferior vena cava. While maintaining forward pressure on the pusher wire, the catheter/sheath assembly is withdrawn to permit the proximal strut to exit the catheter. Gentle to-and-fro motion on the pusher wire secures this strut and its anchoring hooks in the inferior vena cava. The pusher wire is then rotated counterclockwise IO to I5 turns to disengage it from the filter, after which the pusher wire and empty filter catheter are removed. Thesheath is then repositioned, and vena cavography repeated to contrm filter placement.

Successful infrarenal filter placement was achieved in all 5 patients by the femoral approach. Although generally a simple technique, passage of the 12Fr sheath and filter catheter was difficult in 1 case in which the inferior vena cava was distorted by retroperitoneal tu- mor. The entire procedure, from vena cavography to completion, usually required 20 to 30 minutes. No acute complications, such as groin or retroperitoneal hemato- ma, were noted. Anticoagulation was used when possible after the procedure. During follow-up of 1 to 4 months, there was no clinical evidence of local femoral vein thrombosis, vena caval thrombosis, recurrent pulmonary embolism or Jilter migration.

The commercially available Greenfield vena cava fil- ter offers caval patency in greater than 95% of cases with a low rate of recurrent pulmonary embolism (Table I). Although initially designed for placement by venous cut- down, percutaneous methods of delivery have been devel- oped and are widely used.8 Despite this and other im- provements, technical problems such as angulated and misplaced filters, which may fail to protect the patient from pulmonary embolism,2T3 and local complications such as femoral vein thrombosis, which may be related to trauma from the 24Fr filter carrier device,6 still occasion- ally occur.

1276 THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 66

The Gianturco-Roehm Bird’s Nest Filter, designed for percutaneous insertion only, is effective with inci- dences of clinically suspected recurrent pulmonary embo- lism of 2.7% and inferior vena cava occlusion of 2.9% after 6 months in 440 patients receiving the initial first and second generations of this device.7 Potential advan- tages when compared to the Greenfield filter include a negligible incidence of clinically recognized femoral vein thrombosis when delivered percutaneously from this site. As the Bird’s Nest filter is a cluster of wires, meticulous alignment within the inferior vena cava, as with the Greenfield filter? is unnecessary. Additionally, after a design change incorporating rigid filter struts, there have been no reported cases of Bird’s Nest filter migration. However, as migration may be related to poor seating in an oversized vena cava, caution is recommended with this device when inferior vena cava diameter exceeds 40 mm.

Randomized clinical trials of the Bird’s Nest, Green- field, and other investigational vena cava filters are lack- ing. Until such data are available, the choice of device should be based on the operator’s experience, the clinical situation and analysis of the current published reports.‘O

Our experience with the Bird’s Nest filter has been favor- able, and it has proved useful in the management of a difficult and fortunately uncommon clinical problem.

1. Kanter B, Moser KM. The Greenfield Vena Cava filter. Chest 1988;93:170- 175. 2. Otchy DP, Elliott BM. The malpositioned Greenfield filter: lessons learned. Am Surg 1987;53:580-583. 3. Goff JM, Puyau FA, Rice JC, Kerstein MD. Problems in placement of the Greenfield Inferior vena cava filter. Am Surg 1988;54:544-547. 4. Deutsch L. Percutaneous removal of intracardiac Greenfield vena caval filter. AJR 1988;151:671~679. 5. Kim D, Porter DH, Siegel JB, Simon M. Perforation of the inferior vena cava with aortic and vertebral nenetration bv a suurarenal Greenfield filter. Radiolom 1989;172:721-723. ’

, . 1,

6. Kantor A, Glanz S, Gordon DH, Sclafani SJA. Percutaneous insertion of the Kimray-Greenfeld filter: incidence of femoral vein thrombosis. AJR 1987; 149:1%%1066. 7. Roehm JOF, Johnsrude IS, Barth MH, Gianturco C. ‘The Bird’s Nest inferior vena cava filter: nroeress reoort. Radiokwv 1988:168:745-749. 8. Pais SO, M&is gE, De&his DF. P~cutan~ous insertion of the Kimray- Greenfield filter: technical considerations and problems. Radiology 1987;165: 377-381. 9. Katsamouris AA, Waltman AC, Delichatsios MA, Athanasoulis CA. Inferior vena cava filters: In vitro comparison of clot trapping and flow dynamics. Radiolo- gy 1988;166:361-366. 10. Dorfman GS. Percutaneous inferior vena caval filters. Radiology 1990; 174987-992.

Frequencies of Reactions to lohexol Versus loxaglate James L. Vacek, MD, Lisa Gersema, PharmD, Mark Woods, PharmD, Carol Bower, ES, and Gary D. Beauchamp, MD

R adiographic contrast material causes a variety of complications and reactions. In an attempt to mini-

mize these events, alternative contrast agents have been developed, which either reduce the osmolality per iodine molecule, or reduce the number of charged particles in solution, or both.1-8 Reduction of charged particles in solution makes some of the newer agents less chemotoxic than older ionic agents.5,6*9 It has been demonstrated that the nonionic contrast agents have fewer hemodynamic and electrophysiologic effects than their ionic counter- parts. Myocardial contractility and vascular motor tone are less affected by the newer agents, as are heart rate and myocardial depolarization and repolarization.1,4,6a7 It has been shown that nonionic agents such as iohexol and iopamidol cause fewer allergic, “anaphylactoid” reac- tions than standard ionic agents.8,9 Little data compare the incidence of reactions with a low osmolar nonionic agent such as iohexol with the low osmolar ionic dimer, ioxaglate. The purpose of this study was to examine the occurrence of such events in a group of patients treated at the same institution with I or the other of these a.gents over the same time period under similar circumstances.

This study was performed as a Department of Phar- macy focus investigation at St. Luke’s Hospital of Kan- sas City, Missouri. E5e hospital records of 534 consecu-

From the Mid-America Heart Institute, St. Luke’s Nospital, Mid- America Cardiology Associates, 4320 Wornall, Suite 40-11, Kansas City, Missouri 64111. Manuscript received April 9, 1990; revised man- uscript received and accepted June 18, 1990.

tivepatients who were studied in the cardiac catheteriza- tion laboratory in November and December 1989 were reviewed ,for the occurrence of adverse or allergic reac- tions. Patients underwent coronary angiograms orpercu- taneous transluminal coronary angioplasty, or both, and received either iohexol or ioxaglate for radiographic contrast (Table I). In 5 cases, the type of contrast was not speciJied, resulting in a study group of 529. None of these 5 patients had an adverse reaction. Cardiac cathe- terization and angioplasty were performed using stan- dard technique. Each cardiologist at our center uses only 1 of the newer agents for all his cases, based on which he feels is safest. As there is no significant cost difference for these agents at our hospital, each cardiologist always uses his preferred Substance for all patients, both high and low risk. No routine premeditation for prophylaxis of allerg&~ reactions was g’ven unless a history of con- trast allergy was obtained, in which case prednisone and dip~enhyd~amine were administered before the proce- dure. Most patients received either no sedativepremedi- cation for their procedure or small intravenous or oral dosages of a benzodiazepine such as diazepam or mid- azolam. All patients undergoing angioplasty received 10,000 h/of heparin intravenously at the beginning of the procedure, augmented by additional boluses of 5,000 U at hourly intervals or as dictated by activated clotting times performed in the catheterization laboratory. Hep- arin was not routinely used for angiography without angioplasty. Plastic syringes were used in all cases. Ad-

.THE AMERICAN JOURNAL OF CARDIOLOGY NOVEMBER 15, 1990