Authors: Wissarut Sakulpaptong, Choutchung Tinakorn Na Ayudhya, Luxica Jarutasnangkul, Sittinop Titichoatrattana, Suphot Srimahachota, Pairoj Chattranukulchai
Categories: Case Report, Idiopathic, Reno-caval fistula, High-output heart failure, Endovascular intervention, Case report
Source: Radiology Case Reports
Authors: Wissarut Sakulpaptong, Choutchung Tinakorn Na Ayudhya, Luxica Jarutasnangkul, Sittinop Titichoatrattana, Suphot Srimahachota, Pairoj Chattranukulchai
An aortocaval fistula is a rare vascular connection between the aorta and inferior vena cava, often caused by abdominal aortic aneurysm, trauma, or infection. It can result in high-output heart failure due to increased venous return and reduced systemic vascular resistance, typically presenting with right-sided symptoms. Renal arteriovenous and reno-caval fistulas are even rarer, with no prior reports of spontaneous idiopathic reno-caval fistulas. A 67-year-old man with hypertension and paroxysmal atrial fibrillation presented with 10 months of generalized edema and exertional dyspnea. He had no history of abdominal trauma or surgery. Examination revealed signs of congestive heart failure and a central abdominal bruit. Echocardiography showed chamber dilation and pulmonary hypertension. Computed tomographic angiography identified a right reno-caval fistula between the right renal artery and inferior vena cava, with associated right renal infarction. The patient underwent successful endovascular embolization using a vascular plug, with gradual resolution of symptoms and improved echocardiographic findings. In cases of high-output heart failure with right-sided symptoms, arteriovenous fistula should be considered, as specific interventions can be highly effective. This rare case underscores the value of a multimodal diagnostic approach combining clinical evaluation and imaging to ensure accurate diagnosis and successful treatment.
An aortocaval fistula is an abnormal connection between the inferior vena cava (IVC) and the aorta. It most commonly arises from an abdominal aortic aneurysm—accounting for approximately 80% of cases—but may also result from penetrating trauma, mycotic aneurysms, or connective tissue disorders [[1], [2], [3]]. This condition can cause high-output heart failure due to elevated central venous pressure and increased venous return. Additionally, the reduction in systemic vascular resistance can exacerbate activation of the renin-angiotensin system, further contributing to the hemodynamic burden. Patients may present predominantly with right-sided heart failure symptoms, such as generalized edema or ascites [4,5]. Rarely, variants of aortocaval fistulas involve renal arteriovenous fistulas or the even less common reno-caval fistula, with a reported prevalence of less than 0.04% [6,7]. These vascular anomalies connecting the renal artery to the venous system are most often acquired (70%-80%), with fewer cases being congenital (14%-27%) or idiopathic (3%-5%) [4,6,7]. To date, only idiopathic renal arteriovenous fistulas have been documented in the literature [8], while spontaneous or idiopathic reno-caval fistulas have not been previously reported. Here, we present a rare case of a spontaneous or idiopathic reno-caval fistula leading to high-output heart failure.
A 67-year-old man presented for routine follow-up of hypertension and paroxysmal atrial fibrillation. He had no history of abdominal surgery, trauma, or prior vascular intervention. The patient reported bilateral leg edema persisiting for 10 months, followed by progressive exertional dyspnea on exertion and paroxysmal nocturnal dyspnea over the preceding 7 months, resistant to diuretic therapy. On physical examination, his blood pressure was 133/69 mmHg with a regular heart rate of 84 beats/min. He was mildly tachypneic (respiratory rate of 22 breaths/min), with warm, well-perfused skin and normal capillary refill. The internal jugular veins were distended (5 cm above the sternal angle) with prominent V waves. The apical impulse was displaced to the left 6th intercostal space at the anterior axillary line, with a hyperdynamic precordium. Auscultation revealed a grade II/VI systolic ejection murmur at the left upper parasternal border without radiation, and a grade III/VI diastolic blowing murmur at Erb’s point. Fine end-inspiratory crepitations were noted in both lower lung fields. Abdominal examination revealed hepatomegaly with positive fluid thrill, and bilateral leg pitting edema. A systolic abdominal bruit was audible at the periumbilical region. The rest of the physical examination was unremarkable.
These findings indicated congestive heart failure with predominant right-sided features—jugular venous distension, hepatomegaly, ascites, and peripheral edema. The murmur characteristics suggested pulmonic regurgitation with possible relative pulmonic stenosis due to high-flow states. The presence of a periumbilical systolic bruit raised suspicion of an arteriovenous shunt in the mid-abdominal region as the underlying cause. Chest radiograph showed a cardiothoracic ratio of 0.8, with prominence of the left atrial appendage, right atrium, and main pulmonary trunk; inferior displacement of the left ventricular (LV) apex; and mild pulmonary venous congestion (Fig. 1). Electrocardiography revealed atrial fibrillation with a moderate ventricular response, LV hypertrophy, left axis deviation, and poor R-wave progression. Transthoracic echocardiography demonstrated a dilated LV with severe eccentric hypertrophy and global hypokinesis, resulting in reduced systolic function (LV ejection fraction of 37%). The right ventricle (RV) was markedly dilated with impaired systolic function, and both atria were severely enlarged (Fig. 2A). Valvular findings included moderate functional mitral regurgitation, mild aortic regurgitation, severe functional tricuspid regurgitation with annular dilation, and a thickened pulmonic valve with severe regurgitation. Doppler studies revealed moderate pulmonary hypertension (mean pulmonary arterial 37 mmHg; RV systolic 52 mmHg), with a stroke volume index of 37.4 mL/m² and diastolic flow prolongation in the aortic isthmus and abdominal aorta (Fig. 2B). The subcostal view showed a markedly dilated IVC and hepatic veins (Fig. 2C). Laboratory tests, including complete blood count and thyroid function, were within normal limits. Right and left heart catheterization confirmed pre-capillary pulmonary hypertension (mean PAP: 37 mmHg) and elevated cardiac output, with a cardiac index of 5.7 L/min/m². The Qp/Qs ratio was 2.2:1, and oxygen saturation in the distal IVC was markedly elevated (95.6%), indicating a left-to-right shunt. Aortography revealed an aortocaval fistula in the suprarenal region. Coronary angiography was also performed due to impaired LV function, revealing 90% stenosis of the mid-left anterior descending artery (LAD)Fig. 1Chest radiograph shows a cardiothoracic ratio of 0.8, with prominence of the left atrial appendage, right atrium, and main pulmonary trunk; inferior displacement of the left ventricular apex; and mild pulmonary venous congestion.Fig 1Fig. 2Transthoracic echocardiography demonstrates markedly dilated all cardiac chambers (A), diastolic flow prolongation in the abdominal aorta (B), and a markedly dilated inferior vena cava and hepatic veins (C). IVC; inferior vena cava.Fig 2
Arterial-phase abdominal computed tomographic angiography (CTA) images revealed a dilated and tortuous right main renal artery connecting to the posterior aspect of the suprarenal IVC (Figs. 3A and B, Supplementary vdo 1) leading to early contrast opacification in the markedly dilated suprarenal and hepatic segments of the IVC (Figs. 4A and B, Supplementary vdo 2), consistent with a reno-caval fistula with a fistulous width of approximately 11 mm. (Fig. 4C). Additionally, severe cortical thinning of the hypo-perfused upper pole of the right kidney was observed (Figs. 3A and 4A), indicative of renal infarction, while the accessory right renal artery supplying the lower pole remained patent.Fig. 3Volume-rendered images from abdominal computed tomographic angiography (A, posterior view; B, anterior view) show a dilated, tortuous right main renal artery connecting to the posterior aspect of the suprarenal IVC (). The upper pole of the right kidney is hypo-perfused. Ao; aorta, IVC; inferior vena cava, RK; right kidney, LK; left kidney.Fig 3Fig. 4Arterial-phase abdominal computed tomographic angiography axial images show a dilated, tortuous right main renal artery connecting to the posterior aspect of the suprarenal IVC (A), leading to early contrast opacification of the markedly dilated hepatic segments of the IVC (B). The sagittal view (C) demonstrates a fistulous width of approximately 11 mm (). Severe cortical thinning of the hypo-perfused upper pole of the right kidney is also seen (A). Ao; aorta, IVC; inferior vena cava, RK; right kidney.Fig 4
After stabilizing the patient's heart failure, a multidisciplinary team discussion was held. The patient and family opted for transcatheter closure of the fistula. A No. 14 ChekFLO Vascular Plug (Eclipse Medical Co.) was successfully deployed at the fistula site. Post-deployment aortography confirmed marked reduction in shunt flow.
Given his single-vessel coronary disease and LV dysfunction, percutaneous coronary intervention was also performed. A drug-eluting stent was placed in the mid-LAD, achieving complete revascularization with no residual stenosis.
At 6-week follow-up, the patient reported significant symptomatic improvement, with resolution of right-sided heart failure signs and only mild residual exertional dyspnea. Follow-up chest radiograph showed normalized pulmonary vasculature and reduced cardiothoracic ratio. Echocardiography demonstrated substantial reduction in chamber sizes and improvement in biventricular function. Residual valvular lesions included moderate pulmonic regurgitation, mild mitral regurgitation, and trace tricuspid regurgitation. RV systolic pressure had decreased from 52 mmHg to 23 mmHg.
One of the recognized causes of high-output heart failure is an abnormal fistula between the systemic arterial and venous systems, such as an aortocaval fistula, which connects the IVC and the abdominal aorta. This condition has a reported incidence of approximately 0.2%-1.3% and can result from a variety of causes, including abdominal aortic aneurysm complications, penetrating trauma, connective tissue diseases, and mycotic aneurysm [[1], [2], [3]]. Clinical presentation varies depending on the timing and progression of the fistula. In acute cases, high-output heart failure may occur with minimal signs of venous congestion, reported in fewer than 20% of cases. In contrast, chronic aortocaval fistula cases—such as in our patient—are more likely to present with symptoms of right-sided heart failure, including jugular venous distension, generalized edema, hepatomegaly, and venous stasis, along with tachycardia, hypertension, and widened pulse pressure [1,2,4,5]. Although aortocaval fistulas are rare, even less common are their anatomical variants, such as renal arteriovenous and reno-caval fistula, with an estimated incidence of less than 0.04% [4,6]. In this report, we describe an unusual case of right-sided heart failure caused by a spontaneous reno-caval fistula.
Our literature review indicates that the majority of reported reno-caval fistulas have been associated with penetrating trauma, firearm injuries, or iatrogenic procedures such as nephrectomy or laparoscopic cholecystectomy [6,7,9]. The time from inciting event to diagnosis ranged from a few hours to as long as 34 years. Most cases involved male patients aged 8 to 52 years. Consistent with our case, all trauma-related reno-caval fistulas occurred on the right side, likely due to the anatomical proximity of the right renal artery to the IVC [4]. Only 1 prior case of a congenital or spontaneous reno-caval fistula has been reported, which involved a left-sided fistula associated with an anomalously positioned IVC [6].
Renal arteriovenous fistulas commonly present with abdominal bruits (in >70% of cases), hypertension with cardiomegaly (50%), and congestive heart failure (32%). Gross hematuria, resulting from relative ischemia of the renal parenchyma distal to the shunt, is observed in approximately 21% of cases [10]. Our patient exhibited congestive heart failure, cardiomegaly, and a characteristic abdominal bruit. Despite evidence of renal infarction on CTA, no hematuria was reported, likely due to the limited infarct size and the chronic, insidious progression of the fistula.
Transthoracic echocardiography is often the initial imaging modality in patients presenting with congestive heart failure due to an arteriovenous fistula. Findings may include increased cardiac output, right heart dilation, tricuspid regurgitation, and pulmonary hypertension [3,5]. Many patients maintain preserved LV ejection fraction. However, our patient had impaired LV systolic function, likely secondary to coexisting coronary artery disease. An additional echocardiographic feature suggestive of arteriovenous shunting is diastolic flow prolongation in the aortic isthmus and descending aorta—a finding present in this case as well [5].
Historically, surgical management—including nephrectomy, renal artery ligation, or reconstruction—was the primary treatment modality for reno-caval fistulas from the 1960s to 1980s [[11], [12], [13]]. More recently, transcatheter arterial embolization has become the preferred approach. However, in cases of large, high-flow fistulas, this method may be less effective and carries a risk of pulmonary embolism due to inadvertent migration of embolic material [4,6]. Endovascular stenting of the renal artery is an alternative option [4].
In our case, the patient had a right renal artery diameter of 23 mm and a fistula measuring 11.5 mm, which was successfully occluded with a No. 14 ChekFLO Vascular Plug (Eclipse Medical Co., Ltd.). Larger fistulas have been treated with alternative devices, including an Amplatzer septal occluder (Abbott/St. Jude, MN, USA) with a 30 mm disc diameter [14].
In patients presenting with high-output heart failure, particularly with right-sided signs and symptoms, arteriovenous fistula should be considered in the differential diagnosis, as targeted therapies are available and can yield excellent outcomes. This rare case highlights the importance of a multimodal diagnostic approach—integrating detailed history-taking, thorough physical examination, and appropriate imaging—to achieve accurate diagnosis and guide successful, definitive treatment.
IVC, inferior vena cava; LV, left ventricle; RV, right ventricle; LAD, left anterior descending artery; CTA, computed tomographic angiography.
Ethics comittee approval was waived.
The data for this case report is located at King Chulalongkorn Memorial Hospital, Bangkok, Thailand.
WS, CA and PC were responsible for the conception and design of the work as well as data analysis and interpretation. WS, ST, LJ, SS, and CA were responsible for data collection. All authors were responsible for the final approval of the version to be published.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.