Subclavian Artery Pseudoaneurysm in an Unusual Case of Digital Gangrene.

A young male patient presented at a tertiary care hospital with cold and bluish left upper limb accompanied with digital gangrene arousing suspicion of peripheral vascular disease. History did not reveal any high-risk behavior. Clinical examination and subsequent investigations lead to the diagnosis of acute infective endocarditis of native aortic valve along with peripheral embolism caused by methicillin-resistant Staphylococcus aureus. Fogarty's balloon embolectomy was done following which patient developed pseudoaneurysm of the left subclavian artery. These iatrogenic sequelae were managed with the resection of the pseudoaneurysm and prolonged antibiotic therapy as per the culture and sensitivity report.

Introduction

Incidence of infective endocarditis (IE) has remained somewhat constant since the past era despite improvement in the diagnosis and treatment.[1] Acute IE by Staphylococcus aureus (including infrequently reported community-acquired methicillin-resistant Staphylococcus aureus [MRSA]) has a rising trend and may present with rapid progression and systemic sequelae.[123] Several studies have reported MRSA infections in populations lacking the previous contact with health-care facilities.[45] Transthoracic echocardiography and sequential blood cultures are essential confirmatory tools. We hereby present a case of acute MRSA endocarditis; with rapidly progressive digital gangrene and hence masquerading as peripheral vascular disease (PVD). A high index of suspicion, subsequent investigations, identification of the etiologic agent, and antibiotic sensitivity testing assured appropriate pharmacotherapy and eventually stopped further progression and resulted in cure of the infection. The iatrogenically induced pseudoaneurysm was also timely managed without further complications.

Case Report

A 21-year-male patient presenting with pain and bluish discoloration of the left upper limb for 2 days and high fever for 1 week was referred to the department of cardiology for peripheral angiography for suspected PVD. There was no history of joint pain, rash, convulsion, myocardial infarction, any hypercoagulable state, recent or past hospital stay, central venous cannulation, and intravenous drug abuse. Clinical examination revealed ischemic changes in left upper limb with early gangrenous changes of left hand distal to the metatarsophalangeal joints. Pulse was absent in left upper limb from axillary artery downward, high volume collapsing pulse was found in other limbs. His blood pressure was 140-30 mmHg. Peripheral signs of aortic regurgitation (AR) were present, and Hill's sign was positive at 50 mmHg. Jugular venous pressure was normal, and apex was at left 5th intercostal space just outside the midclavicular line. Auscultatory findings were suggestive of severe AR. No definite past history suggestive of rheumatic fever could be obtained.

Working clinical diagnosis was that of peripheral embolism in a case of IE of the aortic valve with severe aortic incompetence. Routine blood examination revealed Hb - 9.8gm%, TLC - 18900/mm3, and neutrophil - 87%. Renal parameters and liver function were normal. Chest X-ray revealed mild cardiomegaly and electrocardiogram showed left ventricular hypertrophy. Serum ANA (hep2), Anti-ds DNA, P-ANCA, C-ANCA, homocysteine, antiphospholipid antibody, anticardiolipin antibody, B2 glycoprotein1, and markers for hypercoagulable states: All were negative. On transthoracic echocardiography, oscillating vegetation was seen attached to the right and noncoronary cusp of aortic valve along with coaptation failure of the aortic valve with severe AR [Figures 1 and 2]. Both aortic and mitral valve were slightly thickened at the commissures. Left ventricle was mildly dilated (left ventricular internal diameter diastolic = 59 mm, left ventricular ejection fraction - 58%, and no regional wall motion abnormality). Two consecutive blood cultures (more than 12 h apart) were sent before administration of antibiotics. Ceftriaxone and gentamicin were started as empirical therapy. Doppler ultrasonography (USG) study showed sluggish flow across left brachial, ulnar, and radial artery.

Figure 1

Vegetations in the right and noncoronary cusps of aortic valve in two-dimensional echocardiography.

Figure 2

Severe aortic incompetence seen in color Doppler echocardiography.

Balloon embolectomy by Fogarty's catheter was performed, and pulse in the left upper limb improved slightly. However, fever continued. After 3 days, a pulsatile painful swelling appeared in left infraclavicular region. Doppler USG followed by exploration of the swelling revealed pseudoaneurysm (3.5 cm × 2.5 cm × 3 cm) of subclavian artery [Figure 3], with collection of pus and slightly enlarged surrounding lymph nodes. The pseudoaneurysm was excised, and aspirated pus was sent for culture and sensitivity. On obtaining pus and blood culture reports of MRSA and concurrent antibiograms, antibiotic therapy was rescheduled with vancomycin for 6 weeks and gentamicin for 4 weeks along with monitoring of renal parameters. Patient regained feeble pulse in the left upper limb. However, gangrenous part could not be salvaged. Fever responded with 4 weeks of antibiotic therapy. We inferred the final diagnosis as MRSA-mediated acute IE of aortic valve (probably with preexisting rheumatic heart disease), complicated with mycotic embolic phenomenon and iatrogenic mycotic pseudoaneurysm.

Figure 3

Pseudoaneurysm of subclavian artery seen by peripheral arterial Doppler.

Discussion

Despite the decreasing incidence of rheumatic heart disease and increased frequency of degenerative valve disease, annual incidence of IE (4–10/100,000 population) and associated mortality (1/100,000 per year) have remained constant.[6] Valvular leaflets are quickly destroyed by bacteria multiplying rapidly within the ever-growing friable vegetations. The manifestations result from either embolic or intracardiac suppurative complications. Early complications (within a week) include dyspnea and fatigue of severe congestive heart failure and a wide spectrum of neuropsychiatric complications resulting from central nervous system involvement.[17] Frequently, the presence of endocarditis is disguised. The diagnosis is worth consideration in any patient who has unexplained fever, has organ involvement that may be attributed to embolic phenomenon, or appears to have a multisystem disease. The incidence of peripheral embolization is highest with S. aureus endocarditis although digital gangrene is rarely reported. The systemic involvement owing to embolic phenomenon in the decreasing order of frequency is splenic, cerebral, pulmonary, renal, and coronary followed by the extremities.[8]

Pseudoaneurysm is defined as a localized, irreversible dilatation of an artery by at least 1.5 times its normal diameter, and the disruption of the vascular wall caused by an infection of a previously normal artery or more rarely as a result of secondary infection of a preexisting aneurysm.[910] When associated with acute endocarditis, the pathogenesis is related to the release of septic emboli of cardiac focus through the bloodstream, lodgment in atherosclerotic plaques, or vasa vasorum causing inflammation of the vessel wall, with consequent damage and dilatation of the arterial wall.[10] Rarely, pseudoaneurysm may complicate embolectomy (6%) because of intimal linear or full-thickness tears or disruption of the vessel wall.[1112] Here, the cause might be either destruction of arterial wall with catheter-related intervention and/or colonization of the bacteria and very rapid destruction of the wall by bacterial exotoxin. Rapid peripheral embolization and later on mycotic pseudoaneurysm formation justify high virulence of the concerned infective agent. Community-associated MRSA isolates often possess a novel Type IV SCCmec, as well as the PVL gene, which encodes a virulent exotoxin.[23]

Brachial artery and peroneal artery pseudoaneurysm following Fogarty's balloon embolectomy have been reported in the past, but not subclavian artery pseudoaneurysm.[11] Our case illustrates an unusual presentation of IE and highlights the complication of interventional management. The approach should be based on the assessment of clinical course, imaging studies, laboratory results for confirmation of etiology, and guided administration of appropriate antibiotic therapy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.