Abstract

We present a case of splenic rupture as the cause of a sudden drop in blood pressure soon after mitral valve surgery for infective endocarditis. This case suggests that, in addition to more common causes of unstable vital signs after valvular surgery, such as cardiac tamponade or bleeding at the operation site, splenic rupture, although rare, should be considered in the differential diagnosis. This is particularly important in the case of infective endocarditis.

Keywords

cardiac tamponade; endocarditis: infective; heart valve prosthesis implantation; mitral valvesplenic rupture;

1. Introduction

Mitral valve replacement is often necessary to manage mitral valve endocarditis to eradicate the infection and prevent embolization. Common causes of unstable vital signs or even death after mitral valve replacement include hypovolemia, congestive heart failure, atrioventricular disruption, ventricular arrhythmia, and myocardial infarction.¹ However, splenic rupture has also been identified as one of the life-threatening complications after infective endocarditis.^2,3 Splenic rupture is rarely considered if it occurs immediately after mitral valve surgery. Here, we present a case of splenic rupture taking place 12 hours after mitral valve replacement for infective endocarditis. It was diagnosed by computed tomography and successfully treated with splenectomy.

2. Case Report

The case was a 61-year-old man undergoing mitral valve replacement for infective endocarditis. His medical history included hypertension, stroke, and uneventful cholecystectomy. He denied any form of drug abuse. He sought medical help for persistent fever.

Physical examination following admission showed that his blood pressure was 109/68 mmHg, pulse rate was 78 per minute, and a grade III/VI systolic murmur was audible. Blood culture yielded coagulase negative staphylococci. Mitral valve vegetation, severe mitral regurgitation and moderate tricuspid regurgitation were identified on cardiac sonography. After 3 weeks’ antibiotic treatment, valvular surgery was arranged. Xenograft mitral valve replacement (31 mm Hancock II valve; Medtronic Inc., Minneapolis, MN, USA) and tricuspid annuloplasty in DeVega fashion were performed via right thoracotomy. Cardiopulmonary bypass was introduced through the femoral artery and vein with 108 minute perfusion time and 70 minute cross-clamp time. At the end of surgery, activated clotting time was corrected to 124 seconds and his blood pressure was maintained around 115/75 mmHg with dopamine 5 μg/kg per minute.

His initial intensive care unit (ICU) stay was smooth until 12 hours after surgery when his systolic blood pressure suddenly dropped to 70 mmHg. Fluid resuscitation and then norepinephrine infusion were used but with only limited effect. Emergency transesophageal echocardiography showed a mass of soft density to the side of the left ventricle. Although his blood pressure was finally restored to 107/61 mmHg after addition of epinephrine infusion, revision surgery was still performed under the impression of cardiac tamponade. No hematoma was found in either side of the chest cavity or in the pericardial space. At this juncture, gradual abdominal distension was noted. Peritoneal tapping was positive for sanguineous fluid. Abdominal computed tomography confirmed splenic hematoma and intraperitoneal fluid accumulation (Figure 1). Emergency splenectomy was performed and the excised spleen showed a rupture (Figure 2), with a hematoma inside and an irregular margin at the rupture site. Blood, and clots from blood, shed into the peritoneal cavity was estimated at about 2500 mL in total. After splenectomy, his condition became stable and inotropics and vasopressors were tapered gradually. He stayed in the ICU for another 10 days and was then returned to the ward.

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Figure 1 Abdominal computed tomography.

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Figure 2 Ruptured spleen.

3. Discussion

Splenic rupture is an uncommon complication with infective endocarditis. The possible mechanisms include rupture of a mycotic aneurysm of the splenic artery,^4,5 spleen abscess rupture,⁶ or suppurating rupture of intrasplenic vessels with hematoma enlargement causing a capsular tear.² It has been reported that there is an incidence of splenic infarction and abscess of 19% in valve replacement for left side infective endocarditis, and that abdominal computed tomography should be performed to screen for this.⁶ In our case, the gross appearance of the ruptured spleen was pink in color with an irregular surface. There were numerous hematomas of considerable size but no abscess was observed. As a result, mycotic aneurysm rupture with hematoma enlargement was determined to be the reason for splenic rupture.

Abdominal pain, especially in the left upper quadrant, is one of the earliest symptoms of splenic rupture after endocarditis besides hypotension and tachycardia.^7,8 In Sugimoto et al’s report, the patient complained of left upper abdominal dull pain for 3 days before the incident of splenic rupture which happened 11 days after mitral valve replacement.⁸ In our case, abdominal pain, which was apparent 12 hours after surgery, had not been mentioned due to unclear consciousness, possibly because of residual anesthetic and cardiopulmonary bypass effects, or sepsis. Therefore, infective endocarditis-related splenic rupture which occurs immediately after mitral valve replacement is difficult to diagnose correctly in the first instance.

There are also reports of spontaneous spleen rupture solely due to anticoagulation or thrombolytic therapy.^9,10 Anticoagulation during cardiopulmonary bypass, although subjected to reversal at the end of surgery, may also insidiously cause intrasplenic bleeding, hematoma enlargement, and eventually rupture of the spleen.

Because of the highly life-threatening characteristics of splenic rupture if not diagnosed and treated promptly, we suggest that routine imaging of the abdomen, to rule out the possibility of splenic rupture, should be performed when there is a sudden blood pressure change during management of infective endocarditis, especially when the patient cannot convey abdominal discomfort. If splenic abscess or splenic artery aneurysm is found before rupture, surgical treatment is recommended because conservative treatment usually fails to forestall rupture.^4,11