Jpn J Thorac Cardiovasc Surg (2006) 54:486–489
DOI 10.1007/s11748-006-0035-0

CASE REPORT

Massive pulmonary embolism after off-pump coronary artery
bypass surgery
Masaki Hashimoto, MD, PhD · Masakazu Aoki, MD
Yasuhide Okawa, MD · Hiroshi Baba, MD
Yoshiyuki Nishimura, MD

Received: 6 June 2006 / Accepted: 22 August 2006
© The Japanese Association for Thoracic Surgery 2006

Abstract An 88-year-old woman developed an acutemassive pulmonary embolism after off-pump coronary
artery bypass surgery. She experienced dyspnea while
walking on the sixth day after operation. Her chest
radiograph showed pleural effusion. Initially, she wastreated for heart failure due to bypass graft occlusion. A
repeat echocardiogram revealed enlargement of the rightventricle. Multislice computed tomography showed amassive embolus in the pulmonary artery. Surgical embolectomy was performed, and her postoperative course
was easy. Recently, the incidence of pulmonary embolism in Japanese people has been rising. In addition, widespread implementation of off-pump coronary
artery bypass compromises the protective effect against
pulmonary embolus after cardiac surgery. Although theincidence of pulmonary embolism after coronary artery
bypass surgery is still low in Japan in comparison to thatin Western countries, prophylaxis against pulmonary
embolism after off-pump coronary artery surgery is becoming more important.
Key words Pulmonary embolism · Off-pump CABG ·Prophylaxis

Introduction
Although pulmonary embolism after coronary artery
bypass surgery is not uncommon in the West, it is still
M. Hashimoto (*) · M. Aoki · Y. Okawa · H. Baba ·Y. Nishimura
Division of Cardiovascular Surgery, Toyohashi Heart Center,21-1 Gobudori, Oyama-cho, Toyohashi, Aichi 441-8530, Japan
Tel. +81-532-37-3377; Fax +81-532-37-3366e-mail: hashimoto@heart-center.or.jp

uncommon in Japan. This article describes a case of
massive pulmonary embolism after off-pump coronary
artery bypass surgery.

Case
An 88-year-old woman was referred to our hospital because of exacerbation of effort angina. She had been
medicated with an antihypertensive drug, aspirin, nitrate, and a hypolipidemic agent by her family doctor forthe past 10 years. She had no history of thrombosis. Herangina had gotten worse over the last 2 weeks. Her bloodpressure was 188/98 mmHg, and her heart rate was 72/
min with regular rhythm. Auscultation revealed no abnormality in the heart or lungs. Her electrocardiogram
revealed ST depression in leads I, aVL, V5, and V6.
Coronary angiography revealed severe three-vessel
coronary artery disease with complete occlusion of theleft anterior descending artery and the circumflex artery.
An intraaortic balloon pump (IABP) was inserted for theangina. On the day after admission, off-pump coronary
artery bypass grafting (CABG) was performed with bothan internal mammary artery and a left great saphenous
vein graft. After administration of 12 000 units of heparin sodium intravenously, the activated clotting time(ACT) was >407 s. The right internal mammary artery
was anastomosed to the left anterior descending artery,which was deeply buried underneath myocardium andfat. The left internal mammary artery and the saphenous
vein graft were anastomosed to the left posterior branch
and the right posterior branch, respectively. The heparin
was neutralized with 120 mg protamine sulfate, and theACT was 133 s after administration. She was withdrawn
from the IABP right after the operation. She was easilyJpn J Thorac Cardiovasc Surg (2006) 54:486–489

weaned from mechanical ventilation (total intubation
time was 11 h after operation). Her blood gas analysis
was good, with oxygen supplementation 5 l/min througha face mask. Aspirin was started on the third postoperative day.
Six days after the operation she experienced dyspnea
while walking. Her chest radiograph showed pleuraleffusion. She was treated with diuretics for congestive
heart failure. Because of tachypnea and dyspnea, she
could not withdraw from oxygen supplementation. Her
pulse oximetry was 95%–98% with oxygen supplementation (5 l/min) through a mask without a reservoir.
She complained of dyspnea and anxiety on day 12
after the operation. Her chest radiograph showed nochange except pleural effusion. The electrocardiogram
revealed ST depression in leads V4 to V6. Her pulse oximetry showed 93%–94% with the same oxygen supplementation. An emergency coronary angiogram revealed total
occlusion of the right internal mammary artery to theanterior descending artery and stenosis of the vein graft
to the right posterior descending artery, which suppliedcollateral flow to the left anterior descending artery. It
was difficult to insert a pulmonary artery catheter into
the pulmonary artery and we could not wedge it. The
systolic pulmonary artery pressure, diastolic pressure,and mean pressure were markedly high: 60, 27, and
34 mmHg, respectively. At this time she was diagnosed
with heart failure due to graft occlusion. A stent wasimplanted into the distal anastomotic region of thesaphenous vein graft.
Her condition did not change, however, and thedyspnea was getting worse. Her blood gas analysis was
PaO2 75.9 mmHg and PaCO2 37.0 mmHg with oxygen
supplementation (5 l/min) through a mask without areservoir. Her blood pressure was 92/63 mmHg. Repeat
echocardiography revealed right ventricular enlargement. Contrast multislice computed tomography (CT)revealed a massive embolus in the pulmonary artery on
both sides (Fig. 1). Her lower legs bilaterally showed nosymptoms of deep vein thrombosis. V/Q scanning was
not performed.
Surgical embolectomy was selected instead of thrombolytic treatment or other catheter intervention as thedefinite onset time was unknown. Surgical embolectomy
was performed urgently. Under intermittent deep hypothermic circulatory arrest (DHCA), the right pulmonary
artery was opened longitudinally behind the ascending
aorta. Endoscopy revealed a massive pulmonary embolus. (Fig. 2) The embolus was totally removed undervideo assistance. Following that, the left pulmonary
artery was opened, and an incision was made from themain pulmonary trunk to the left pulmonary artery.
The embolus here was removed in the same fashion.

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Fig. 1 Contrast multislice computed tomography revealed a massive embolus in the pulmonary artery

Fig. 2 Endoscopy during operation revealed a pulmonary embolus (*)

The total DHCA time was 24 min. After that, to confirm
that there was no residual embolus in the right atrium,
right atriotomy was performed. After operation, herblood gases improved to PaO2 401.8 mmHg and PaCO2
32.7 mmHg with 100% O2 supplementation from a tracheal tube. Moreover, her systolic pulmonary arterypressure, diastolic pressure, and mean pressure underwent marked decreases to 27, 14, and 21 mmHg, respectively. The inferior vena cava filter was inserted on theright after the second operation.
Anticoagulation with Coumadin was started on thethird postoperative day. Because her postoperative
course was quite good, she was withdrawn from oxygen
supplementation.

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Discussion
Pulmonary embolism (PE) after coronary artery surgery,associated with high morbidity and mortality, is notuncommon in the West.1 PE occurs in approximately
0.3%–0.7% after coronary artery surgery, and deep veinthrombosis (DVT) occurs in almost 20% as seen byultrasonographie screening. In contrast, quite a few
cases have been reported in Japan,2,3 although a prospective large cohort study for estimating the incidence of PE
and DVT after cardiac surgery is lacking. This is the firstcase of PE after both coronary and other cardiac surgeries in our institution. We have undertaken 1712 cardiac
surgeries in 7 years: 787 cases of coronary artery surgery
and 925 of other cardiac surgeries. The incidence of PE
among the coronary artery surgeries is estimated at0.0013% and the incidence for the cardiac surgeries at0.0006% in our institution. These incidences are much
lower than those reported in Western countries.
The incidence of PE after coronary artery bypass
surgery is lower than that after other general surgeries.
Generally, patients with cardiovascular surgery receive alarge amount of heparin intraoperatively—in the rangeof 40 000 to 50 000 units—to keep the activated clotting
time >400 s with the hope of preventing clots from forming during surgery. Moreover, hemodilution during
cardiopulmonary bypass compromises clotting and aggregation. In addition, routine antiplatelet therapy withaspirin or another agent is administered after bypass
surgery. Probably the large amounts of heparin administered, hemodilution after cardiopulmonary bypass, andantiplatelet therapy after surgery offer some protection
against DVT and PE.
Coronary artery surgery without cardiopulmonary
bypass (OP-CABG) has become widespread in recentdays. Hemodilution after OP-CABG is less than thatafter coronary artery bypass with cardiopulmonary bypass (CABG). Moreover, the heparin dose is reduced
during OP-CABG. These measures can compromise theprotective effect against PE and DVT. Our case was after
OP-CABG, whereas we did not have a PE case after
CABG. Cartier and Robitaille reported three cases of PEand two cases of DVT among 500 OP-CABG patients.4
They found that the incidence of DVT and PE after
OP-CABG is double that after CABG (1.0% and 0.5%,respectively). Although, these incidences did not reachstatistical significance in their cohort, the findings raise
an alarm about the importance of DVT and PE prophylaxis after OP-CABG. In our experience, the incidence ofPE after CABG is 0%, whereas that of after OP-CABG
is 0.002%.
DVTs and PEs are also increased in Japan because ofthe development of diagnostic methods and recent life

Jpn J Thorac Cardiovasc Surg (2006) 54:486–489

style changes. The death toll due to PE increased 2.8-foldduring the past decade in Japan.5 The incidence of fatal
PE is 28 per 1 million in Japan in compared to 500/
100 000 in the United States. This extremely low incidence in Japan may be influenced the incidence after
coronary artery surgery. In future, the incidence of DVTand PE may increase among those undergoing cardiac
surgery. Accordingly, PE prophylaxis after cardiac surgery increases in importance.
We prescribed early ambulation and routine aspirin
use after coronary artery surgery. In contrast, we did not
use PE prophylaxis, such as graded compression stocking (GCS), sequential compression devices (SCDs), or
other pharmacologic agents, such as Coumadin, lowmolecular-weight heparin (LMWH), or unfractionatedheparin (UFH). In the case described, delayed ambulation and IABP insertion may have contributed tothe PE formation. Some guidelines recommend PEand DVT prophylaxis after several general surgeries,including general, orthopedic, gynecologic-obstetric,urologyic, and trauma surgery, as well as neurosurgery.
There is no recommendation for cardiovascular surgery.
Some PE and DVT prophylactic measures after coronary artery surgery have been reported. In those reports,prophylaxis using a combination of early ambulation,
GCS, SCD, aspirin, dipyridamole, and subcutaneous
heparin (both LMWH and UFH) are considered effective.1,6 SCD is difficult to use in normal, early ambulatingpatients. Dipyridamole has the side effect of tachycardia
and increases oxygen consumption by the heart, making
it difficult to administer in this setting. Subcutaneous
heparin administration right after surgery intensifies therisk of bleeding.
The combination of GCS, routine use of aspirin, andearly ambulation may be useful for preventing DVT andPE after coronary artery surgery. In a nonambulating,high-risk patient with slow recovery, however, a moreaggressive prophylaxis regimen may be necessary for its
prevention. Further investigations are needed to obtainthe accurate incidences of PE and DVT after coronary
artery surgery and to prove the effectiveness of prophylaxis and these measures in Japanese populations.
Conclusion
We report a rare case of PE after OP-CABG. The diagnosis of PE is still challenging, and it is difficult to reachan early diagnosis. Because of widespread implementation of OP-CABG and the increasing number of PEs inJapanese people, PE prophylaxis after OP-CABG is now
strongly recommended. The combination of routine useof GCS, early ambulation, and oral aspirin may beuseful.

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References
1. Shammas NW. Pulmonary embolus after coronary artery bypass surgery: a review of the literature. Clin Cardiol 2000;23:637–44.
2. Nawa Y, Masuda Y, Imaizumi H, Yoshida H, Kihara C,Okada Y, et al. A case of pulmonary thromboembolism after
cardiac surgery Masui 2004;53:547–50.
3. Saito T, Terada Y, Fukuda S, Sakao Y, Takayama T, Suma H,et al. Acute pulmonary thromboembolism after coronary artery
bypass grafting. Kyobu Geka 1991;44:1003–5.

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4. Cartier R, Robitaille D. Thrombotic complications in beatingheart operations. J Thorac Cardiovasc Surg 2001;121:920–2.
5. Japanese Circulation Society. Guidelines for the diagnosis,treatment and prevention of pulmonary thromboembolism anddeep vein thrombosis (JCS 2004) J Cardiol 2005;45:349–366.
6. Ramos R, Salem BI, De Pawlikowski MP, Coordes C,Eisenberg S, Leidenfrost R. The efficacy of pneumatic compression stockings in the prevention of pulmonary embolism after
cardiac surgery. Chest 1996;109:82–5.