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24. Gersh BJ, Kronmal RA, Schaff HV, et al. Long-term (5-year) results of coronary bypass surgery in patients 65 years old or older: CASS. Circulation 1983;68(Suppl II)II-190.

25. Jeffery DL, Vijayanager RR, Bognolo DA, Eckstein PF. Results of coronary bypass surgery in elderly women. Ann Thorac Surg 1986;42:550-3.

26. Kennedy JW, Kaiser GC, Filsher LD, et al. Multivariate discriminant analysis of the clinical and angiographic perdic- tors of operative mortality from the Collaborative Study in

21.

28.

Coronary Artery Surgery (CASS). J Thorac Cardiovasc Surg 1980;80:876-87. Sheldon WL, Rincon G, Pichard AD, et al. Surgical treatment of coronary artery disease. Prog Cardiovasc Dis 1975;28:237- 53. Loop FD, Lytle BW, Cosgrove DM, et al. Coronary artery bypass graft surgery in the elderly. Cleve Clin J Med 1988;55:23-34.

Pacemaker-induced superior vena cava syndrome: Consideration of management

Timothy Blackburn, MD, and Marvin Dunn, MD. Kansas City, Kuns.

The superior vena cava (SVC) syndrome is an unusual but important complication of transvenous endocardial pacing. Transvenous pacemakers have been used for over 20 years, and it is estimated that over one million of these devices have been implanted.’ There are less than 25 case reports in the literature describing the SVC syndrome as a complication of cardiac pacing. As a result, the best method of treatment for this potentially lethal condition remains unclear at this time. We present a case report of a patient recently treated at our institution. The clinical course in this case is charac- teristic of the reports in the literature and raises several points for discussion.

Exemplary patient. A 59-year-old man who had mitral and aortic valve prostheses for rheumatic heart disease presented for evaluation of facial edema and erythema including the periorbital areas. The patient had taken a trip to Florida from which he returned 3 weeks prior to admission. Just prior to leaving Florida, he noticed the onset of facial edema and erythema, which he attributed to sun exposure

From the University of Kansas Medical Center, College of Health Sciences and Hospital.

Supported by a research grant from the A. W. and Nellie B. Armstrong Foundation, Inc.

Received for publication March 21, 1988; accepted Apr. 25, 1988. Reprint requests: Marvin Dunn, MD, Division of Cardiovascular Diseases, University of Kansas Medical Center, 39th & Rainbow Blvd., Kansas City, KS 66103.

and possibly to photosensitivity from amiodarone that the patient was taking for refractory supraven- tricular arrhythmias. The patient was seen by his primary care physician upon return from his trip. At that time he also complained of a dull, low-grade headache and a feeling of fullness in his head. Examination was remarkable only for the facial edema and erythema, and for prosthetic first and second heart sounds. Laboratory studies were nor- mal. The amiodarone was discontinued and the patient was scheduled to return in 2 to 3 weeks.

At the follow-up visit, the patient had persistence of the previously described symptoms. Physical examination was now remarkable for bilateral arm edema, varicosities of the superficial veins of the chest and posterior deltoid region, as well as of the hypogastric and epigastric veins of the abdomen. Marked facial and periorbital edema and chemosis were present, and the patient complained of fatigue of several days’ duration. He was admitted for evaluation and treatment of SVC syndrome.

The past medical history was remarkable for rheumatic heart disease. “Inflammatory rheuma- tism” was diagnosed at age 10. Twenty-six years later, the patient required mitral valvulotomy, and at age 46 a tranvenous endocardial pacemaker was placed for sick sinus syndrome. The entire pacing system required replacement after 4 years. At age 55, 9 years after the original pacemaker placement, another replacement was necessary due to pace- maker lead fracture resulting in pacemaker failure.

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This time the old lead was firmly adherent to the endocardium and could not be removed. It was severed with the free end resting in the SVC.

In 1987, at the age of 58, the patient had a St. Jude mechanical aortic valve implanted and replacement of the previously positioned Starr-Edwards mitral valve with a St. Jude valve. At the time of surgery, the patient was noted to have considerable stenosis of the SVC just above the right atrium. This made the passage of a Swan-Ganz catheter difficult, and passage of a finger retrograde from the right atrium was impossible. Because there were no related symp- toms, repair of this lesion was not deemed necessary at the time. Postoperative venacavogram revealed stenosis of the SVC without thrombosis or extensive collaterals.

The patient did quite well from the time of his valve replacements until this admission, which was 18 months later. He had been maintained on warfa- rin because of the prosthetic valves, and the pro- thrombin time remained remarkably stable at 17 to 17.5 seconds. On admission, a computerized tomo- gram of the chest was obtained to exclude extrinsic compression of the SVC. No masses were seen, but several varicosities were noted in the cervical and superior mediastinal regions. A superior venacavo- gram was obtained and was compared to the previ- ous study. There was now thrombosis involving the proximal SVC, both innominate veins, and both subclavian veins. Some collateral circulation was seen in the neck and chest wall, with dilated poste- rior intercostal veins and drainage into the azygos vein.

A trial of fibrinolytic therapy was undertaken. The warfarin was discontinued and baseline studies were obtained that included a fibrinogen level of 240 mg/ml and fibrin degredation products less than 40 mg/ml. A bolus of 30,000 U of urokinase was given, followed by a continuous infusion of 90,000 U per hour. The dose was increased to 120,000 U per hour to maintain a fibrinogen level in the range of 80 to 100 mg/ml, and the infusion was continued for a total of 6 days. Fibrin degredation products increased to more than 40 mg/ml. The patient had resolution of his headache, fatigue, and feeling of fullness. The edema of the face, arms, and cornea and the elevation of the jugular venous pulse were markedly improved. Repeat venogram showed com- plete clearing of the thrombus in the right subcla- vian vein, partial recanalization of the left subclavi- iif; ,,,d ;~ll~ominate veins, and patency with residual stenosis of the SVC. The patient received an addi- tional 6 days of heparin therapy and the warfarin

was reinstituted. The patient was discharged after the prothrombin time reached therapeutic levels. He has remained free of facial edema and continues to progress satisfactorily.

Comments. The temporal course of events in this patient is similar to that in other reported cases. Thrombosis in the absence of coexistent stenosis tends to occur early.2 This has been seen with Hickman catheters and with Swan-Ganz catheters as well. When venous thrombosis occurs due to long-term indwelling venous catheters (Hickman- Broviac) or pacemaker leads, most thrombotic events occur within the first year of implantation. There is usually some stenosis at the site of throm- bosis when thrombosis occurs after 1 year. Similarly, when stenosis of the SVC reaches such severity as to become clinically apparent, it is usually associated with new thrombus formation. We could find few instances of stenosis causing the SVC syndrome without new thrombus formation.3T4 As stenosis of the SVC increases in severity, venous collaterals develop that reroute blood to the inferior vena cava. The combination of SVC stenosis and increased venous collaterals probably results in decreased SVC flow, which predisposes to thrombus forma- tion. However, it is difficult to be certain of the temporal relationship of the fibrotic narrowing and the thrombosis. A likely pathogenetic mechanism is thrombosis, followed by fibrous scarring, which causes SVC stenosis. When SVC blood flow is further reduced due to venous collateral formation, thrombosis reoccurs and results in total SVC occlu- sion and the SVC syndrome.

Other typical features in this patient are the location of the stenosis and the presence of more than one pacemaker lead within the venous system. Although only one lead is necessary to cause the changes described above, several of the previously reported cases4-l were associated with the presence of more than one lead, usually one intact and one severed and retracted.

The precise location of the stenosis in the segment of the SVC just above the right atrium is intriguing. Stoney et al8 showed that venous occlusion can occur anywhere along the course of the pacemaker lead. Lagergren et al.,9 in their study of autopsy cases, noted that whenever the leads came in contact with the vascular endothelial lining the lead was incorporated into the vessel and was overgrown by fibrous tissue and endothelium. A common area for this fibrosis was in the SVC just above the right atrium, at the site of the stenosis found in most reported cases, including our own.‘, 5, g, lo, 12* l*, lg It is

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probable that this location is favored because of pacemaker electrode tension at this site. Since the pacemaker lead curves as it leaves the SVC and enters the right atrium and ventricle, it probably contacts the endothelial wall with tension at this point. This contact may result in fibrosis or even stenosis. It might be speculated that the presence of more than one pacemaker lead would increase con- tact with the endothelium and therefore cause more extensive fibrosis. Contact between the endothelium and the pacemaker lead could also occur during lead movement resulting from atria1 or ventricular con- traction. The reason why fibrosis should develop in some patients to the point of occlusion of the SVC is yet to be explained, but pacemaker electrode tension may be a factor.

The fact that our patient responded to fibrinolytic therapy 3 weeks after the onset of symptoms is of interest. The patients described in the literature who were successfully treated with thrombolytic therapy were treated very soon after presenta- tion.5*6*11 It has been shown in studies of deep venous thrombosis that, in general, the less time that expires between the onset of symptoms and the initiation of thrombolytic therapy, the greater the likelihood of response. Theiss et al.,13 in a study of deep venous thrombosis of the iliac and/or femoral veins, showed at least partial resolution of throm- botic occlusion in 94%) 82 % , and 69% of patients with treatment occurring less than 3 days, 1 to 2 weeks, and 3 to 4 weeks, respectively, after the onset of symptoms. Our patient received a partial re- sponse to urokinase that resulted in resolution of the clinical symptoms 3 weeks after onset. This is consistent with the results of the study of Theiss et a1.13

Finally, other options for treatment of this condi- tion must be considered. The earliest cases were treated with bed rest and anticoagulation with hep- arin and subsequently with warfarin. Good results were obtained and many patients remained asymp- tomatic during a follow-up period of up to 36 months.7s l* Some of these patients were noted to have extensive superficial venous collaterals, reflect- ing redirection of venous return to the inferior vena cava. Surgical repair by thrombectomy and patching or replacement of the diseased segment of the SVC have been done successfully.‘, 12, ls Thrombolytic therapy followed by anticoagulation with heparin and subsequently with warfarin has resulted in the resolution of thrombus and symptoms in several patients.6r6*11,12 Recently,5 angioplasty of the SVC has been used successfully to eliminate or reduce the

Pacemaker-induced SVC syndrome 895

stenosis. We considered the possibility of bypassing the stenosis with a spiral vein graft formed from the saphenous vein. The graft would attach to the SVC above the stenosis and empty into the right atri- um.

The decision to treat with fibrinolysis and antico- agulation in this case was mainly the result of the patient’s refusal to consider surgery or any proce- dure that could potentially lead to surgery. We therefore chose to maintain therapy with warfarin at a higher therapeutic dose in hopes that the SVC and venous collaterals opened by urokinase would remain patent. The patient remains asymptomatic after 2 months of follow-up. In addition to the symptoms of the SVC, pulmonary emboli, thrombo- sis of the dural venous sinuses, and death have been described.16* l7

Conctusions. The SVC syndrome is an unusual complication of cardiac pacing that carries signifi- cant risk. The best method of treatment for this condition has not yet been determined. Several options for therapy have been discussed, all of which have been successful in the past. The patient pre- sented was successfully treated with fibrinolytic therapy after 3 weeks of symptoms, and he contin- ues to do well on warfarin therapy.

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