167

Impending Paradoxical EmbolismAfter Coronary Artery Bypass GraftingSuccessful Surgical TreatmentVittorio Mantovani, M.D., Mehran Faeli, M.D., Alberto Limido, M.D.,

Sandro Ferrarese, M.D., and Andrea Sala, M.D.

Department of Cardiac Surgery and Cardiology, Ospedale di Circolo-FondazioneMacchi, Universita dell’Insubria, Varese-Italy

ABSTRACT We describe a case of impending paradoxical embolism of a 22 cm long thromboem-

bolus, straddling over a patent foramen ovale, detected by transthoracic and transesophageal

echo 11 days after a coronary artery bypass operation. The patient underwent successful emer-

gency removal of the clot and closure of the patent foramen ovale. A vena cava filter was placed

because of new thrombi detected in deep veins of the legs. (J Card Surg 2003;18:167-169)

A 66-year-old woman underwent triple coro-nary artery bypass surgery because of severestenoses of the left coronary artery main trunkand right coronary artery. The operation was per-formed with standard technique in moderately hy-pothermic cardiopulmonary bypass, requiring fullheparinization. The posterior descending arteryand an obtuse marginal branch were grafted withtwo segments of vena saphena magna, harvestedfrom the left lower limb. The pedicled left internalthoracic artery was grafted to the left anterior de-scending artery. The operation was successfullycompleted with easy weaning from cardiopul-monary bypass; heparin action was reversed byprotamine sulphate as usual.

The patient had been previously treated for sixmonths with transdermic nitrates and antiplateletdrug (ticlopidine, 250 mg a day, Tiklid) becauseof stable effort angina pectoris. Seven days be-fore the operation she had begun subcutaneousenoxaparine treatment (Clexane, 8000 i.u. twicea day) because of angina instabilization, which

Address for correspondence: Dott. Vittorio Mantovani, De-partment of Cardiac Surgery, Ospedale di Circolo-FondazioneMacchi, Universita dell’Insubria, Viale Borri 57, 21100, Varese,Italy. Fax: 390332264394; e-mail: vitmantovani@hotmail.com

led to coronarography and subsequent surgery.Beginning on postoperative day two, the ticlopi-dine treatment was resumed. The patient wasdischarged in good general condition and withoutsymptoms of deep vein thrombosis on postop-erative day nine to a rehabilitation center, wherea routine admission transthoracic echocardiogra-phy showed normal cardiac function and absenceof any intracardiac mass. A screening echographyof the deep veins of the legs demonstrated bilat-eral proximal thrombi. The treatment with enoxa-parine, 100 i.u./kg twice a day, and oral warfarinwas immediately undertaken.

The morning of postoperative day 11 the pa-tient presented chest pain, cough, sweating,and mild dyspnea. Transthoracic echocardiogra-phy showed a mass in the right atrium origi-nating from the interatrial septum and protrud-ing into the right ventricle. The pictures werestrongly suggestive of a mass in the left atrium aswell, also originating from the interatrial septum.The patient was immediately sent back to ourunit, where a transesophageal echocardiography(Fig. 1) showed a snake-like clot in the rightatrium protruding into the left atrium through apatent foramen ovale. Emergency surgery wasthen undertaken. During cardiopulmonary bypass

168 MANTOVANI, ET AL. J CARD SURGIMPENDING PARADOXICAL EMBOLISM 2003;18:167-169

Figure 1. Transesophageal echocardiography of the clot in the right atrium, straddling over the foramen ovale (arrow)into the left atrium. AO = aorta; RA = right atrium; LA = left atrium; RV = right ventricle.

and aortic cross-clamping the right atrium wasopened: one end of the clot was in the right ventri-cle, and the rest of it was straddling the foramenovale. The interatrial septum was incised horizon-tally and the clot removed without fragmentation.Both atria were closed with running sutures, andthe operation was uneventfully concluded.

The patient had an excellent recovery with earlyextubation and no clinically evident neurologicalimpairment. The day after this second operationa new echography of the legs showed a mobilethrombus in the left femoral vein. This findingwas confirmed by contrast CT scan, and a Green-field filter (Meditech, Watertown, Mass, U.S.A.)was placed in the inferior vena cava. The rest ofthe postoperative course was uneventful: cere-bral subclinical embolism was excluded by CTscan while the clinical diagnosis of submassivepulmonary embolism was confirmed by perfu-sion pulmonary scintigram. The patient was dis-charged with oral anticoagulation therapy.

DISCUSSION

Deep vein thrombosis (DVT) and pulmonaryembolism (PE) are significant complications ofmany surgeries; their incidence may reach 50to 70% and 1 to 6%, respectively, after or-thopaedic surgery.1 The clinical diagnosis of DVTis extremely difficult under normal conditions andpractically impossible after saphenectomy. In aretrospective study of 1033 cardiac surgical pa-tients,2 PE developed in 33 cases, but in onlyone case was the clinical diagnosis of DVT estab-lished before PE. Massive PE often causes sud-den death while the most common symptomsand signs of submassive PE are part of a normalpostoperative course of bypass surgery: chestpain, cough, tachycardia and tachypnea, mildpleural effusion, and so on. While in orthopaedicsurgical patients most DVT are in the operatedleg,3 in coronary bypass patients DVT affectsequally the contralateral leg and ispilateral leg to

J CARD SURG MANTOVANI, ET AL. 1692003;18:167-169 IMPENDING PARADOXICAL EMBOLISM

the saphenous vein graft harvest site.4,5 In a re-cent review by Shammas6 the average incidenceof DVT and PE after coronary artery bypass graft-ing was 23% and 0.3 to 0.7%, respectively.

Paradoxical embolism is a well-known andfeared complication of heart diseases causingright-to-left shunt. A patent foramen ovale (PFO)is present in almost one third of the general pop-ulation7 and may open during Valsalva maneu-ver and coughing, allowing spontaneous transientright-to-left shunt. PFO is thought to be an impor-tant predisposing factor for systemic embolism.A few cases of impending paradoxical embolismthrough a PFO are already described in the lit-erature;8,9 to our knowledge this is the first dis-cussed after a coronary artery bypass operation.In our opinion the problem of DVT and PE in coro-nary artery bypass patients is underestimated,and strategies to diagnose and prevent it shouldbe developed.

REFERENCES

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