Inferior vena caval and right atrial thrombus complicating amoebic liver abscess

Abstract

We present the result of right atrial thrombectomy in a paediatric patient suffering from a right atrial thrombus due to amoebic liver abscess under total circulatory arrest. A 2-year old boy with amoebic liver abscess complicated by inferior vena cava (IVC) thrombus extending up to the right atrium (RA) was operated on in our institute. During the surgery, the thrombus was removed from the IVC and the RA under deep hypothermic circulatory arrest. After chest closure, open drainage of the abscess was performed. Metronidazole was given postoperatively for 2 weeks. The postoperative period was uneventful. There was rapid convalescence with complete resolution of the abscess. Anticoagulation with warfarin was started on the day following surgery and continued for 6 weeks. There was no recurrence of thrombosis or embolic events in the follow-up period. Extension of thrombus into the right atrium mandates an aggressive surgical approach which may prove life saving. It is crucial in the prevention of pulmonary embolism or Budd–Chiari syndrome, which may have an overall poor outcome.

INTRODUCTION

Inferior vena cava (IVC) thrombosis is a rare but life-threatening complication of amoebic liver abscess (ALA). The optimal management in this clinical subset is not well defined. We recently encountered a paediatric patient with ALA with IVC thrombosis extending into the right atrium (RA). We hereby present the cardiac surgeon's perspective in this clinical setting.

PATIENTS AND METHODS

A 2-year old boy presented to our institute with high-grade fever and cough for 4 days associated with distension of abdomen. There was tender hepatomegaly and ascitis. Ultrasonography of the abdomen showed a large abscess in segments IV and VIII of the liver. Amoebic serology was positive. Intravenous metronidazole was started. Percutaneous drainage was attempted but failed due to thick fluid. Repeat ultrasound after 1 week showed thrombosis of the IVC. Echocardiography showed free-floating thrombus in the RA extending from the IVC. Considering the risk of pulmonary embolism, urgent surgery was planned.

SURGICAL TECHNIQUE

Median sternotomy and vertical pericardiotomy was performed. Cardiopulmonary bypass (CPB) was established with aortocaval cannulation. The pulmonary artery was dissected and clamped. After cooling to 20°C, cardioplegic arrest was achieved with cold blood cardioplegia. Total circulatory arrest was established. The RA was opened parallel to the atrioventricular groove. The thrombus was extracted. The IVC was thoroughly irrigated with normal saline. The circulation was temporarily restarted to flush any small remnant thrombus in the IVC. The venous cannula was advanced into the SVC and the SVC was snugged. Circulation was restarted and the RA was closed. Transoesophageal echocardiography confirmed complete removal of the thrombus. CPB was weaned off after rewarming. After reversal of systemic heparinization, open drainage of the abscess was performed.

RESULTS

The perioperative course was uneventful. The CPB and aortic cross-clamp times were 62 and 20 min, respectively. Total circulatory arrest time was 6 min. ICU stay of the patient was 3 days. Anticoagulation with warfarin was started on the day following surgery and continued for 6 weeks. At 4-month follow-up, there was no evidence of recurrent thrombosis in hepatic vein, IVC or RA.

DISCUSSION

Thrombosis of the hepatic vein and the inferior vena cava is an exceedingly rare complication of ALA. The exact pathogenesis of IVC thrombosis in association with ALA is uncertain. The inflammatory process in the wall of the abscess may spread and cause injury to the intima of hepatic vein or IVC, leading to inflammation followed by thrombosis. The process is usually initiated in the hepatic vein from where the thrombus extends into the IVC and may reach up to the RA. Mechanical compression of the IVC by causing alteration in flow dynamics leading to turbulence and stasis may lead to thrombosis. Rupture of abscess into the IVC may also predispose the same to thrombus formation.

Extension of thrombus into the RA is rare and there have been only few published case reports in the literature (Table 1).

Table 1:

Case reports of inferior vena cava and right atrial thrombus complicating amoebic liver abscess

Author	Year	Case	Treatment	Complications	Outcome
Hodkinson et al. [1]	1988	50-year old labourer	Conservative (oral metronidazole + aspiration of abscess + anticoagulation)	None	Complete resolution of thrombus (both IVC and RA)
Barcat et al. [2]	1998	–	Conservative (oral metronidazole + intravenous anticoagulation followed by thrombolysis)	None	Resolution of thrombus
Sadaf et al. [3]	2009	46-year old labourer	Surgical removal (metronidazole + ultrasound guided drainage of abscess + operative removal of RA thrombus + anticoagulation with low-molecular-weight heparin followed by warfarin)	None	Unremarkable recovery
Zia-ur-Rehman et al. [4]	2010	32-year old computer operator	Surgical removal (ultrasound guided drainage of abscess + operative removal of thrombus under CPB + anticoagulation with heparin followed by warfarin + metronidazole)	None	Uneventful recovery, no recurrence of IVC and RA thrombus formation
Touré et al. [5]	2012	52-year old Senegalese man	Conservative [antibiotics (metronidazole/amoxicillin/clavulanic acid) + curative heparin therapy + abscess drainage]	Pulmonary embolism	Disappearance of thrombi
Gupta et al. [6]	2013	6-year old boy	Surgical (operative removal of thrombus under CPB with DHCA + open drainage of abscess + anticoagulation with warfarin + metronidazole)	None	Complete resolution

DHCA: deep hypothermic circulatory arrest; CPB: cardiopulmonary bypass; IVC: inferior vena cava; RA: right atrium.

The most effective therapy for patients with right atrial extension of thrombus remains largely unknown. This issue is critical because the presence of a right heart thromboembolus complicating pulmonary thromboembolism appears to carry a poor prognosis. Chartier et al. [7] reported a mortality rate of 45% in their series of patients with right heart thromboembolism (n = 38). All of these deaths occurred within the first 24 h of hospitalization, underscoring the need to rapidly diagnose and treat right heart thromboembolism. Existing published reports differ in their recommendations for treatment by advocating surgical removal [8], the administration of thrombolytic agents [7] or anticoagulation therapy with heparin [9].

Several reports describe successful thrombolysis in right-sided heart thrombi. The most widely accepted indication for thrombolytic therapy is proven pulmonary embolism with cardiogenic shock. Therapy is also considered when a patient presents with systemic hypotension without shock. Percutaneous catheter-directed retrieval of clots is a promising possibility, but only 4 cases have been reported to date.

Of the published case reports enumerated in Table 1, surgical removal of the right atrial thrombus was resorted to by only three authors. Others (three authors) pursued a conservative line of management. While complete resolution was achieved in all cases, the course of 1 patient reported by Touré et al. [5] was complicated by pulmonary embolism. In our case, a trial of medical treatment failed and as the thrombus was free floating and threatening to embolize, we adopted a more aggressive approach.

Use of CPB and deep hypothermic circulatory arrest (DHCA) to facilitate the removal of thrombus associated with renal tumours is well documented and advocated by several authors [10]. CPB with DHCA has several advantages. There is a bloodless surgical field with reduced risk of pulmonary embolization. Disadvantages of DHCA are extended bypass time as a result of rewarming, greater transfusion requirements, postoperative bleeding and coagulopathy and increased neurological risk. Femoral venous cannulation for IVC drainage can be used for thrombus removal under low-flow CPB, thus avoiding circulatory arrest and its attendant risks. However, femoral cannulation in paediatric patients is not an attractive option owing to the small size of femoral vein.

CONCLUSION

Vascular complications of ALA in the form of IVC and RA thrombosis are rare and potentially life threatening. An aggressive surgical approach may be crucial in large and highly mobile RA thrombus.

Conflict of interest: none declared.