Ann Thorac Surg 2005;80:2366-2368
© 2005 The Society of Thoracic Surgeons
Case report
Coronary Embolism and Subsequent Myocardial Abscess Complicating Ventricular Aneurysm and Tachycardia
Iki Adachi, MD
a
,
Junjiro Kobayashi, MD
a
,
Hiroyuki Nakajima, MD
a
,
*
,
Kazuo Niwaya, MD
a
,
Hatsue Ishibashi-Ueda, MD
b
,
Ko Bando, MD
a
,
Osamu Tagusari, MD
a
a Department of Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan
b Department of Pathology, National Cardiovascular Center, Osaka, Japan
Accepted for publication July 14, 2004.
* Address correspondence to Dr Nakajima, Department of Cardiovascular Surgery, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan (Email: hnakajim{at}hsp.ncvc.go.jp).
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Abstract
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A 62-year-old female experienced a ventricular aneurysm and tachycardia caused by coronary embolism from mitral valve endocarditis. The patient underwent endoventricular patch plasty and cryoablation concomitant with valve replacement and survived without any operative complications. Pathological examination suggested that abscess formation played an important role regarding the disruption of the ventricular wall and development of the ventricular aneurysm and tachycardia. In previous reports, a myocardial abscess caused by a septic embolism has only been diagnosed using postmortem examinations as colony growth around the capillary vessels in the myocardium. We considered that our operation was effective and feasible in such an occurrence.
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Introduction
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Embolic myocardial infarction during native valve endocarditis is a well-described and often encountered clinical entity. However little is known regarding the precise incidence and optimal therapeutic strategies with regard to a myocardial abscess caused by a septic embolism. We herein report a successfully treated instance of infective endocarditis complicated with ventricular aneurysm and tachycardia caused by coronary embolism and subsequent myocardial abscess.
A 62-year-old female experienced cerebral infarction and was admitted to a nearby hospital. She was feverish and blood culture grew S aureus twice. Transthoracic echocardiography demonstrated vegetation on the mitral leaflet. Vancomycin hydrochloride had been administered for 1 month and consequently the blood culture yielded a negative result. No ventricular aneurysm was detected at this point. However sustained ventricular tachycardia occurred several times and cardioversion was required to arrest it. She was referred to our institution for surgical treatment of infective endocarditis and fatal ventricular arrhythmia.
Upon admission the patient was afebrile and physical examination revealed left hemiparesis and a pronounced systolic murmur at the left sternal border. Chest roentgenography indicated a cardiothoracic ratio of 0.58 with lung congestion. Her blood culture was negative. Electrocardiography demonstrated persistent ST-segment elevation in leads V1–V4 and abnormal Q wave in lead aVR (augmented vector right arm). Despite continuous infusion of nifekalant hydrochloride, sustained ventricular tachycardia developed at frequent intervals in the patient. Two-dimensional echocardiography was remarkable for akinesis and aneurysmal formation of the left ventricular apex (Fig 1) and mobile vegetation, measuring 2 cm in diameter, on the anterior mitral leaflet. Doppler imaging revealed severe mitral insufficiency. Coronary angiography indicated total occlusion of the left anterior descending (LAD) artery beyond the second diagonal branch (Fig 2). Cerebral imaging revealed a past infarction of the right frontal cortex without evidence of mycotic aneurysm.
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Fig 1. Preoperative transthoracic echocardiography: apical 4-chamber view demonstrating the left ventricular (LV) aneurysmal formation. (An = aneurysm; LA = left atrium; RA = right atrium; RV = right ventricle.)
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Fig 2. Complete occlusion of the middle portion of the left anterior descending artery (arrow) is indicated on coronary angiography.
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During the operation, the apical wall bulged out particularly at the apex and adhered to the pericardium. We incised the aneurysm from the apex parallel to the LAD artery. In the aneurysm there was no vegetation, but a thrombus existed and was completely removed. Cryoablation was carried out at the line of demarcation between the aneurysm and the contractile myocardium. A purse-string suture of 3-0 polypropylene was positioned and a rounded woven patch (Hemashield; Boston Scientific, Natick, MA) measuring 3 cm in diameter was sutured into place. The remnant of the aneurysmal wall was trimmed and approximated over the patch with a continuous suture. We then inspected the mitral valve. There was no evidence of annular involvement. The mitral valve was replaced by a bioprosthesis.
Pathological examination of the aneurysmal wall demonstrated the presence of a myocardial abscess and a number of gram-positive cocci with intensive acute inflammatory changes and patchy hemorrhagic necrosis. The structure of the myocardium was severely destructed (Fig 3). Culture of the excised aneurysm wall propagated no causative organisms. After administering adjuvant antibiotic therapy with vancomycin hydrochloride and gentamicin sulfate for 3 weeks, the patient achieved a full recovery and attended a programmed rehabilitation course pertaining to neurologic deficits.
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Fig 3. Excised aneurysm of the left ventricle indicating severe destruction of the wall structure. Inset: microscopically, destruction of the myocardium caused by septic inflammation led to coagulative necrosis. Some cocci can be identified in this micrograph, which were positive for Gram stain (hematoxylin & eosin, x400).
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Comment
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Systemic embolization occurs in 22%–50% of patients who are diagnosed with infective endocarditis [1] and embolisms often involve the coronary arteries. Wenger and colleagues reported that 74% of the coronary embolisms occurred in the left side [2]. The LAD artery seems to be more susceptible to embolism [3], because of the disparity between the vessel caliber and the blood flow volume.
Myocardial abscess is usually caused by direct extension from an active valvular infection. It can result in a pseudoaneurysm formation around the mitral and aortic valves and is one of the common complications with regard to infective endocarditis [1]. On the contrary septic embolisms are quite rarely the cause of a myocardial abscess. In previous reports, myocardial abscesses caused by bacterial embolisms were indicated as microabscesses proximate to the capillary vessels in the myocardial tissue and existed at obviously remote sites from the valvular lesions. It was also reported that even a small abscess in the myocardium could be fetal in association with ventricular arrhythmia [4]. Previously this rare entity of myocardial abscess had been recognized only at autopsy [5, 6]. We consider that the extreme rarity of embolic myocardial abscesses as well as the lack of reports presenting any surviving occurrences may be mainly attributed to the necessity of a thorough pathological examination for a definitive diagnosis, because myocardial abscesses can develop anywhere in the ventricular wall.
It is generally accepted that the necrosed or infarcted myocardium is vulnerable to bacterial invasion and abscess formation and can progressively reduce the strength of the ventricular and aneurysmal wall. Weisz and colleagues reported that the mycotic aneurysm in the region of myocardial infarction exhibited a sevenfold higher risk of cardiac rupture as compared with mere infarct without abscess formation [7].
In the present patient studied, occlusion of the LAD artery by a vegetation embolus induced myocardial infarction, ventricular tachycardia, and ventricular aneurysm at the anteroapical portion, which was obviously distant from the valvular lesion. In addition pathological investigation of the aneurysmal wall revealed a large myocardial abscess formed by S aureus, which is known for its virulence, compared with other pathogens [8], as well as its inclination toward embolism and intensive septic inflammation with severe destruction of the myocardial structure. These findings indicated that not only ischemia but also infection of the myocardium played an important role with regard to the development of the ventricular aneurysm and fatal arrhythmia.
For this patient, we were able to successfully repair the left ventricle and circular cryoablation. The ventricular tachycardia completely disappeared and the patient survived without recurrence of infection. Because we were not aware of the presence of the abscess among the myocardial tissue of the aneurysmal wall at the time of the operation, an artificial material was used for an endoventricular patch. However surgical repair without the use of an artificial patch may be warranted in such an occurrence.
In conclusion the patient described herein is of particular interest because of the combined etiologies for the development of the left ventricular aneurysm and arrhythmia. Endoventricular plasty concomitant with cryoablation is effective for the left ventricular aneurysm with myocardial abscess and fatal ventricular arrhythmia caused by septic embolism of the coronary artery.
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References
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- Bayer AS, Bolger AF, Taubert KA, Wilson W, Steckelberg J, Karchmer AW, et al. Diagnosis and management of infective endocarditis and its complications Circulation 1998;98:2936-2948.[Free Full Text]
- Wenger NK, Bauer S. Coronary embolismreview of the literature and presentation of fifteen cases. Am J Med 1958;25:549-557.[Medline]
- Watt AH, Fraser AG, Stephens MR. Q fever endocarditis presenting as myocardial infarction Am Heart J 1986;112:1333-1335.[Medline]
- Schoenfeld MR, Messeloff CR, Han ST, Lepow H. Large abscess of the heart and spleen complicating bacterial (enterococcal) endocarditis Am Heart J 1961;61:818-821.[Medline]
- Sanson J, Slodki S, Gruhn JG. Myocardial abscesses Am Heart J 1963;66:301-308.[Medline]
- Kim HS, Weilbaecher DG, Lie JT, Titus JL. Myocardial abscesses Am J Clin Pathol 1978;70:18-23.[Medline]
- Weisz S, Young DG. Myocardial abscess complicating healed myocardial infarction Can Med Assoc J 1977;116:1156-1158.[Abstract]
- Chu VH, Cabell CH, Benjamin Jr DK, Kuniholm EF, Fowler Jr VG, Engemann J, et al. Early predictors of in-hospital death in infective endocarditis Circulation 2004;109:1745-1749.[Abstract/Free Full Text]
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Abstract
Introduction
