Anomaly of the inferior vena cava and its tributaries

Introduction

Anomalies of the inferior vena cava (IVC) emerge predominantly in males; in 25% of cases, they are asymptomatic for a long time [1] and in most cases become an incidental finding in patients undergoing examination for other pathological conditions [2][3]. IVC anomalies manifest themselves as peripheral venous thrombosis in 5–9% of cases [4–6] among people under 30 years of age and in 82% of cases among people over 40 years of age [7][8]. A variant of aplasia of the hepatic segment of the IVC with drainage into the azygos vein occurs in 0.6% of cases in the population [9][10].

The left renal vein is the most variable tributary of the IVC. There are 4 main types of anomalies of the left renal vein: types 1 and 2 represent variants of the retroaortic left renal vein crossing the aorta from behind and flowing into the IVC at different angles; type 3 represents the annular left renal vein; type 4 is the left renal vein, which flows into the left common iliac vein [10]. In addition to these 4 main types of left renal vein anomalies, unclassified types of anomalies are also encountered in clinical practice [10].

The retroaortic left renal vein is revealed in 0.5–3% of cases [11][12]. Clinical manifestations of the retroaortic left renal vein may be associated with obstructed outflow and include the development of congestive venous hypertension in the kidney, varicose veins of the spermatic cord, and ovarian veins [13].

Description of a clinical case

Patient N., 59 years old, was born on June 21, 1962. He was undergoing inpatient examination and treatment at the neurological center of the Rostov State Medical University clinic from March 14, 2022 to March 25, 2022.

Complaints upon admission were related to unsteadiness when walking and severe dizziness.

The history of the disease was the following: according to the patient, he became acutely ill on March 14, 2022, when severe dizziness developed in the morning after sleep. With a suspected acute cerebrovascular accident, he was urgently taken and hospitalized at the neurological center of the Rostov State Medical University clinic.

Neurological status on admission was assessed as follows: according to the NIHSS scale, it was 2, according to the Rivermead scale, it was 7, according to the Rankin scale, it was 4, and the Barthel index was 50.

Upon admission, spiral computed tomography (SCT) of the brain and the chest was performed.

The conclusion of SCT of the brain was the following: CT signs of a moderately pronounced expansion of the external liquor spaces of a replacement nature. No data on hemorrhagic stroke were obtained.

The SCT conclusion of the chest cavity was the following: CT signs of diffuse aneurysmal dilatation of the ascending aorta, pulmonary hypertension; IVC abnormalities; aortocoronary sclerosis.

Angiography of the thoracic and abdominal aorta included the following: CT signs of diffuse aneurysmal dilatation of the ascending aorta, pulmonary hypertension, anomaly of the IVC related to its transition into the azygos vein, independent flow of the hepatic veins into the right atrium, retroaortic course of the left renal vein, and aortocoronary sclerosis.

MRI of the brain revealed MRI signs of microangiopathy and moderate dilatation of the cerebrospinal fluid spaces. At the time of the examination, no signs of acute/subacute ischemic infarction were detected.

Doppler ultrasound of the brachiocephalic arteries revealed the following: signs of atherosclerosis; on both sides in the area of bifurcation of the common carotid artery there were small calcified atherosclerotic plaques; and hemodynamically insignificant stenosis up to 25–30%.

Transcranial dopplerography detected no local hemodynamically significant stenoses of the arteries of the base of the brain. The speed characteristics of cerebral blood flow were within the age norm, and no asymmetry of the linear velocity of blood flow was detected.

The conclusion based on the data of the experimental psychological study was the following: the subject did not show significant cognitive impairment but there was a slight instability of attention. Thinking was without significant disturbances. A true depressive state was not identified. Personal anxiety was normal.

The conclusion based on the results of daily ECG monitoring was the following: sinus rhythm and moderate sinus arrhythmia were recorded throughout the examination; on the ECG there was a disturbance in the processes of repolarization of the anterolateral sections of the myocardium of the left ventricle; 837 single supraventricular extrasystoles. Heart rate pauses were not detected. The average heart rate at night was 81 beats/min. No diagnostically significant changes in the ST segment relative to the initial level were detected. Heart rate variability indicators were within normal limits. The QT interval did not exceed 440 ms.

The echoCG conclusion revealed the following: based on the obtained ultrasound results, it was suggested that the patient had a malformation of the IVC in the form of aplasia of the hepatic section and its continuation into the azygos vein. The hepatic veins ran independently into the cavity of the right atrium.

In this regard, it was decided to perform SCT with contrast bolus enhancement for the chest organs, abdominal cavities, and retroperitoneal space.

The conclusion of SCT with bolus contrast was the following: CT signs of diffuse aneurysmal dilatation of the ascending aorta, pulmonary hypertension, IVC anomalies related to its transition into the azygos vein, independent flow of the hepatic veins into the right atrium, retro-aortic course of the left renal vein, aortocoronary sclerosis.

When analyzing the obtained SC venograms, it was established that the IVC was located to the right of the abdominal aorta. The renal portion of the IVC received venous blood from the right kidney and went along into the azygos vein past the liver (Figures 1, 2); the left renal vein was located retroaortically and ran into the azygos vein. The azygos vein passed into the chest cavity between the crura of the diaphragm, ascended into the posterior and then into the superior mediastinum (Figure 2) and connected with the superior vena cava in its usual place in the upper mediastinum in the right paratracheal space (Figure 3). The azygos vein at its confluence with the superior vena cava was increased in diameter.

The right renal vein ran into the IVC. The left renal vein and its branches were located retroaortically. The inferior branch of the left renal vein ran into the IVC, and the superior branch ran into the azygos vein. The diameter of the upper branch was 4 times larger than that of the lower one, and therefore the main outflow of venous blood from the left kidney went into the azygos vein (Figure 2).

The prerenal and hepatic segments of the IVC were absent; the hepatic veins ran independently into the right atrium (Figure 4).

The main diagnosis was the following: “Ischemic stroke in the vertebrobasilar region (March 14, 2022), lacunar pathogenetic subtype according to TOAST, an acute period. Vestibulo-ataxic syndrome.” Background disease was the following: “Arterial hypertension of stage III, degree 1, stratification risk of group IV (very high). CHF 1 FC 1”.

Treatment provided was the following: basic diet, sodium chloride 0.9%, succinic acid+inosine+nicotinamide+riboflavin 10 ml, the complex of peptides obtained from pig brain 10 ml, omeprazole 20 mg, acetylsalicylic acid 100 mg, atorvastatin 20 mg.

The condition at discharge was satisfactory, in neurological status with positive dynamics, accompanied by a decrease in the severity of symptoms.

The patient had high rehabilitation potential; the further stage of rehabilitation was in a clinic at the residence place.

At that time, the ranking of his neurological status by different scales was as follows: by the NIHSS scale, it was 1, by the Rivermead score, it was 14, by the Rankin scale, it was 1; the Barthel index was 95.

Discussion

In the presented case, the combination of an anomaly of the IVC and the left renal vein in a 59-year-old male patient was an accidental finding during examination and treatment for an acute disorder of cerebral blood flow.

The identified variant of aplasia of the prerenal and hepatic sections of the IVC with drainage into the azygos vein was the result of atrophy of the right subcardinal vein [1]. Blood from the lower part of the body bypassed from the IVC through the interpeduncular portion of the azygos vein, which developed from the right supracardinal vein, into the superior vena cava.

The retroaortic left renal vein was produced while maintaining the anastomosis between the right and left supracardinal veins. The left renal vein had 2 branches located retroaortically. The inferior branch of the left renal vein ran into the IVC, and the superior branch ran into the azygos vein. The diameter of the upper branch was 4 times larger than that of the lower one; therefore the main outflow of venous blood from the left kidney went into the azygos vein and was directed upward.

Regarding the possible manifestation of an IVC anomaly in people over 40 years of age by the clinical symptoms of peripheral venous thrombosis, and the manifestation of the retroaortic left renal vein by the development of congestive venous hypertension in the kidney, the patient was given the necessary recommendations.

Conclusions

1. Asymptomatic aplasia of the prerenal and hepatic sections of the IVC with drainage into the azygos vein was revealed.
2. The hepatic veins ran into the right atrium.
3. The examination identified a rare, unclassified type of the retroaortic left renal vein, the lower branch of which flew into the IVC, and the upper branch ran into the azygos vein.
4. The possibility of random X-ray radiological findings of anomalies in the development of the IVC and its tributaries was established in people before clinical manifestations.
5. The patient was given recommendations with the consideration of the main diagnosis and possible manifestations of existing anomalies of the IVC and left renal vein.