Saddle pulmonary embolism with right heart strain and incidental detection of aortic-origin splenic artery and dual renal arteries on CT angiography

Abstract

CT pulmonary angiography (CTPA) is the imaging modality of choice for diagnosing acute pulmonary embolism and simultaneously provides detailed assessment of thoracoabdominal vascular anatomy. Recognition of incidental vascular variants is important because these findings may influence future surgical and endovascular procedures. This case highlights the importance of systematic evaluation of all vascular structures on CTPA, even in emergency settings. A 52-year-old man presented with acute chest pain and progressive dyspnea. CT pulmonary angiography demonstrated a large saddle pulmonary embolism extending into the bilateral main pulmonary arteries and segmental branches. Secondary signs of right ventricular strain were present, including right ventricular enlargement (RV/LV ratio 1.55) and leftward bowing of the interventricular septum. Incidentally, CT angiography revealed direct aortic origin of the splenic artery and dual right renal arteries consisting of a hilar artery and an inferior polar artery. The patient underwent catheter-directed thrombolysis followed by anticoagulation therapy, with subsequent clinical improvement. This case highlights the value of comprehensive CT angiographic evaluation in acute pulmonary embolism. In addition to establishing the diagnosis and demonstrating right heart strain, CT identified clinically relevant vascular variants that may have implications for future abdominal surgery, endovascular interventions, and renal transplantation. CT pulmonary angiography plays a dual role by facilitating diagnosis and risk stratification of acute pulmonary embolism while simultaneously identifying clinically significant vascular variants that may influence future patient management.

Introduction

Acute pulmonary embolism (PE) remains a major cause of cardiovascular morbidity and mortality worldwide. CT pulmonary angiography (CTPA) is the current imaging standard for diagnosis and provides valuable information regarding clot burden and right ventricular dysfunction, both of which are important determinants of prognosis [[1], [2], [3]].

Beyond evaluation of the pulmonary vasculature, modern multidetector CT angiography frequently reveals incidental anatomical variants. Although often asymptomatic, recognition of these variants is important because they may influence future surgical and endovascular procedures.

Direct origin of the splenic artery from the abdominal aorta is an uncommon vascular variant reported in less than 1% of cases [4,5]. Multiple renal arteries are more common, occurring in approximately 18-30% of individuals [6,7].

This case underscores the value of a methodical, whole-body approach to CT angiographic interpretation, as incidental but clinically relevant variants may otherwise be overlooked. We report a case of saddle pulmonary embolism with CT evidence of right ventricular strain in which direct aortic origin of the splenic artery and dual right renal arteries were incidentally identified during emergency CT angiographic evaluation.

Case presentation

A 52-year-old man presented to the emergency department with sudden onset chest pain, progressive shortness of breath, and profuse sweating of approximately 3 hours duration.

His medical history was significant for hypertension, diabetes mellitus, coronary artery disease managed medically, gastritis, and bariatric surgery performed 13 years earlier.

On presentation, the patient appeared anxious and diaphoretic. Vital signs showed:

• Heart rate: 113 beats/min

• Blood pressure: 100/60 mmHg

• Respiratory rate: 18/min

• Oxygen saturation: 95% on room air

• Laboratory investigations demonstrated:

• NT-proBNP: 1004 pg/mL

• Troponin I: 0.05 ng/mL.

Imaging findings

CT pulmonary angiography

CT pulmonary angiography demonstrated a large saddle pulmonary embolus straddling the bifurcation of the main pulmonary artery with extension into the right and left main pulmonary arteries and multiple segmental branches bilaterally (Fig. 1).

Fig. 1.

Axial CT pulmonary angiogram showing saddle pulmonary embolism with thrombus straddling the main pulmonary artery bifurcation (arrows) extending into bilateral main pulmonary arteries.

Secondary signs of right ventricular pressure overload were present, including right ventricular enlargement with an RV/LV ratio of 1.55 (RV diameter 3.99 cm; LV diameter 2.57 cm) and leftward bowing of the interventricular septum (Fig. 2). No pulmonary infarction or pleural effusion was identified.

Fig. 2.

Axial CT image at the ventricular level demonstrating right ventricular enlargement (RV diameter 3.99 cm; LV diameter 2.57 cm) with an RV/LV ratio of 1.55 and leftward bowing of the interventricular septum, indicating right heart strain.

Incidental vascular findings

Direct aortic origin of the splenic artery

The splenic artery arose directly from the anterior aspect of the abdominal aorta at approximately the L1 vertebral level rather than from the celiac trunk. The vessel demonstrated normal caliber and followed an expected tortuous course toward the splenic hilum (Fig. 3).

Fig. 3.

Axial CT angiogram demonstrating direct splenic artery origin from the abdominal aorta. Note the absence of typical celiac trunk trifurcation pattern and the normal tortuous course toward the splenic hilum through the splenorenal ligament.

Dual right renal arteries

Two separate renal arteries originated from the abdominal aorta and supplied the right kidney. A dominant hilar artery entered the renal hilum, while a smaller accessory artery supplied the lower pole. The left kidney was supplied by a single renal artery (Fig. 4).

Fig. 4.

3D volume-rendered CT angiogram showing dual right renal arteries – main hilar artery and accessory inferior polar artery. The left renal artery demonstrates normal single vessel anatomy.

Treatment and outcome

Given the large clot burden and imaging evidence of right ventricular strain, the patient underwent catheter-directed thrombolysis using tenecteplase followed by systemic anticoagulation.

The patient's symptoms improved significantly over the next 48 hours. He was discharged on the fifth hospital day with long-term anticoagulation therapy.

At 1-month follow-up, the patient remained asymptomatic, and echocardiography demonstrated normalization of right ventricular function.

Discussion

This case illustrates the value of CT pulmonary angiography as a comprehensive diagnostic tool in the emergency setting. In addition to establishing the diagnosis of acute saddle pulmonary embolism and demonstrating objective evidence of right ventricular strain, CT angiography identified clinically important vascular variants that may influence future procedural planning.

Saddle pulmonary embolism is defined as thrombus lodged at the bifurcation of the main pulmonary artery and accounts for approximately 2.6-5.4% of acute pulmonary embolism cases [1]. Although historically associated with hemodynamic instability, contemporary studies have demonstrated considerable variability in clinical presentation [1,8].

In the present case, CT demonstrated objective evidence of right ventricular dysfunction, including an elevated RV/LV ratio of 1.55 and leftward bowing of the interventricular septum. These findings are established markers of right heart strain and have been associated with adverse outcomes in acute pulmonary embolism [2,[3], [9]]. Together with the elevated NT-proBNP level, these imaging findings supported the diagnosis of an intermediate-risk pulmonary embolism and contributed to therapeutic decision-making.

Direct origin of the splenic artery from the abdominal aorta is an uncommon vascular variant reported in less than 1% of individuals [4,5]. Embryologically, this variation is believed to result from persistence of primitive ventral splanchnic arteries and altered fusion of the longitudinal ventral anastomoses that normally form the celiac trunk. Although usually asymptomatic, recognition of this variant is important because it may influence catheter-based interventions and surgical planning. Selective splenic artery embolization requires direct aortic catheterization rather than conventional celiac artery access. Furthermore, knowledge of variant visceral branch anatomy is important during fenestrated or branched endovascular aortic aneurysm repair and complex upper abdominal surgery.

Multiple renal arteries arise from persistence of transient embryonic vessels supplying the kidneys during their ascent from the pelvis. Accessory renal arteries are common anatomical variants and are particularly relevant in renal transplantation, endovascular procedures, and retroperitoneal surgery [6,7,[10], [11], [12]]. Failure to recognize accessory arteries may result in incomplete revascularization, segmental renal ischemia, or technical difficulties during surgical reconstruction.

Although each of these vascular variants has been described individually in the literature, reports describing their coexistence in the setting of acute pulmonary embolism appear to be exceedingly limited

Although each of these vascular variants is individually recognized, their identification in this patient highlights the importance of systematically reviewing all imaged vascular structures during emergency CT examinations. Incidental findings may provide clinically actionable information with implications extending far beyond the immediate indication for imaging.

Conclusion

This case demonstrates the dual value of CT pulmonary angiography in emergency practice. In addition to diagnosing saddle pulmonary embolism and identifying imaging markers of right ventricular strain, CT angiography revealed clinically relevant vascular variants involving the splenic and renal arteries. Careful evaluation and reporting of incidental vascular anatomy can provide important information for future surgical and endovascular planning.

Key learning points

• •CT pulmonary angiography enables both diagnosis and risk stratification of acute pulmonary embolism.
• •Right ventricular enlargement and interventricular septal bowing are important imaging markers of right heart strain.
• •Direct aortic origin of the splenic artery is an uncommon anatomical variant with implications for endovascular and surgical procedures (e.g., selective embolization, fenestrated EVAR).
• •Multiple renal arteries remain important considerations in renal transplantation and vascular interventions.
• •Systematic review of all imaged vascular structures may reveal clinically relevant incidental findings.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and the accompanying images. The patient's identity has been protected, and no identifying information is included in the manuscript.