Stanford Type B Aortic Dissection in an Adult Patient With Unrepaired Coarctation of the Aorta

Abstract

Coarctation of the aorta (CoA) is a congenital narrowing typically detected in childhood; survival into adulthood without repair is uncommon. Aortic dissection (AD) is an exceedingly rare complication in this specific context, particularly involving the descending aorta. We describe a case of a 46-year-old Caribbean-Black male with a medical history of chronic hypertension (HTN) who presented with unstable angina and hypertensive crisis. Emergent computed tomography angiography revealed critical proximal descending CoA with poststenotic dilatation and an acute Stanford type B AD. He was initially stabilized on guideline-directed medical therapy, and while definitive surgical repair was recommended, the patient declined. This exceedingly rare case of type B AD complicating unrepaired CoA underscores the importance of recognizing congenital aortic disease as a cause of refractory HTN in adults. Additionally, it highlights the need for continued vigilance for long-term complications in adults with congenital heart disease.

Introduction

Coarctation of the aorta (CoA) is a congenital narrowing of the thoracic aorta that typically presents in infancy or childhood and accounts for 5% of all congenital heart defects. ¹ Many patients survive into adulthood undiagnosed, often presenting with chronic hypertension (HTN) and subtle clinical signs such as diminished femoral pulses or differential blood pressures between the arms and legs. ² Up to 75% of CoA patients have a coincident bicuspid aortic valve (BAV), which itself predisposes to life-threatening aortic pathology. ²

Without repair, survival into mid- or late-adulthood is improbable, with most patients dying by the fourth decade of life due to complications such as incipient, intractable heart failure (HF), acute aortic rupture, or catastrophic intracranial hemorrhage (ICH). Aortic dissection (AD) is an uncommon but often fatal late complication of CoA. ² While most ADs in this setting typically involve the ascending aorta (Stanford type A), type B ADs arising distal to the CoA are exceedingly rare. ³

We report a middle-aged, Caribbean-Black male with chronic HTN who presented with acute Stanford type B AD in the context of an unrepaired proximal descending CoA and a trileaflet aortic valve. This case highlights key diagnostic clues, underscores contemporary imaging and management strategies, and provides follow-up recommendations for this rare, albeit devastating clinical scenario.

Case Presentation

The patient is a 46-year-old Caribbean-Black male with a medical history of poorly controlled, chronic HTN (noncompliant) for the past decade, who presented to the emergency department with abrupt, tearing, interscapular pain. He did not report any additional prescriptive medical (essentially nonadherent), recreational, or illicit drug use. His family history was noncontributory. On arrival, he was notably hypertensive with a blood pressure of 202/107 mm Hg on the left arm and 205/111 mm Hg on the right arm. In contrast, his leg blood pressures were circa 133/94 mm Hg bilaterally. His heart rate was 129 beats/minute, respiratory rate was 18 breaths/minute, and peripheral oxygen saturation was 98% on room air, with an afebrile status. The cardiovascular examination revealed bounding radial pulses, with diminished femoral pulses, and a pronounced radial-femoral delay bilaterally. A soft systolic murmur was audible over the left interscapular region. His apical impulse was displaced anterolaterally with a hyperdynamic character, consistent with left ventricular hypertrophy (LVH). The neurological, respiratory, and abdominal examinations were unremarkable. There was no anasarca or peripheral edema.

Initial laboratory investigations, including a complete blood count, renal and hepatic function tests, and cardiac biomarkers, were within normal limits. The 12-lead electrocardiogram demonstrated sinus rhythm with nonspecific ST-T changes (Figure 1). Portable chest radiography revealed a widened mediastinum, more prominent on the left side (Figure 2). Transthoracic echocardiography demonstrated mild-moderate concentric LVH with a preserved left ventricular ejection fraction of 50% to 55%. The aortic valve was trileaflet with mild regurgitation. A dissection flap was visualized in the descending aorta, and Doppler imaging revealed turbulence with a high-velocity gradient in the proximal descending aorta, proximal to the dissection flap, findings suggestive of CoA (Figure 3).

Figure 1.

The patient’s 12-lead ECG displaying sinus rhythm with nonspecific ST-T changes. ECG, electrocardiogram.

Figure 2.

An erect portable CXR (antero-posterior view) demonstrates a prominent cardiomediastinal silhouette and widening of the mediastinum. CXR, chest radiography.

Figure 3.

The patient’s TTE images. (A) A parasternal short-axis view (aortic level) demonstrating a trileaflet aortic valve as opposed to a BAV, which is associated with aortic pathology. (B) A suprasternal view demonstrating an intense Doppler color-flow signal, suggesting the presence of turbulence with a high-velocity gradient in the proximal descending aorta, and CoA. (C) A 3D image reconstruction indicating the CoA and the distal dissection flap within the descending aorta. BAV, bicuspid aortic valve; CoA, coarctation of the aorta; 3D, 3-dimensional; TTE, transthoracic echocardiography.

Urgent contrast-enhanced computed tomography angiography confirmed a severe focal narrowing of the proximal descending thoracic aorta (~8 mm luminal diameter) immediately distal to the left subclavian artery for a 5 mm segment with a poststenotic dilatation segment of 61 mm. An acute Stanford type B AD originated distal to the CoA and extended into the abdominal aorta (Figure 4). Subsequent magnetic resonance aortography (MRA) of the thoracic aorta further delineated the anatomy. It confirmed the CoA and the extent of the AD flap, allowing clear assessment of both true and false lumens (Figure 5). The study also demonstrated poststenotic dilatation and collateral vessels, corroborating the computed tomography aortography (CTA) findings.

Figure 4.

The patient’s CTA series. (A) A contrast-enhanced axial image displaying a focal narrowing of the aortic arch distal to the origin of the left subclavian artery, consistent with CoA (yellow arrow). In contrast, the red arrow highlights dilated collateral intercostal vessels. A small left-sided pleural effusion is also noted. (B) Another contrast-enhanced axial image demonstrates a new loss of the smooth posteromedial contour of the descending thoracic aorta (yellow arrow), whereas the red arrow highlights a new small-volume left pleural collection. The blue arrow shows mural thrombus continuous with an intimal flap at the T5–T6 level, suggestive of a contained aortic leak/rupture. (C) A contrast-enhanced sagittal image revealing focal narrowing of the aortic arch distal to the origin of the left subclavian artery, consistent with CoA (yellow arrow). The red arrow highlights the intimal flap with poststenotic dilatation of the distal descending thoracic aorta. (D) A 3D VR image of the thoracic aorta with a yellow arrow demonstrating focal, smooth narrowing at the aortic isthmus just distal to the origin of the left subclavian artery, consistent with juxtaductal CoA. The red arrow demonstrates poststenotic dilatation of the proximal descending thoracic aorta. CoA, coarctation of the aorta; CTA, computed tomography aortography; 3D, 3-dimensional; VR, volume-rendered.

Figure 5.

The patient’s MRA series. (A) A contrast-enhanced axial image demonstrates focal narrowing of the aortic arch adjacent to and distal to the origin of the left subclavian artery, consistent with CoA (red arrow). The yellow arrow highlights dilated collateral intercostal vessels. (B) A contrast-enhanced sagittal image revealing focal narrowing of the aortic arch distal to the origin of the left subclavian artery, consistent with CoA (yellow arrow). The red arrow highlights the intimal flap with poststenotic dilatation of the distal descending thoracic aorta. CoA, coarctation of the aorta; MRA, magnetic resonance aortography.

The patient was admitted to the cardiac care unit and was initiated on an intravenous labetalol infusion and gradually transitioned to oral angiotensin-converting enzyme inhibitor (lisinopril 40 mg), beta-blocker (BB, carvedilol 25 mg twice daily), calcium-channel blocker (amlodipine 10 mg), and nonsteroidal mineralocorticoid receptor antagonist (finerenone 40 mg daily with high-intensity rosuvastatin 40 mg). After a multidisciplinary discussion, a management plan for open vascular surgery repair was formulated. However, the patient declined any invasive intervention and opted to continue conservative medical management. During the remainder of his hospitalization, there were no interval adverse events, and he was eventually discharged with follow-up care from cardiology and vascular surgery. He remained asymptomatic and hemodynamically stable, with normalized blood pressures.

Discussion

This case features the rare concurrence of CoA with a Stanford type B AD in adulthood. ⁴ CoA is a congenital narrowing of the proximal descending aorta, which is usually detected in childhood. ¹ In untreated individuals with CoA, the prognosis is generally poor, with an average survival of only 34 years, with the vast majority of deaths occurring before the age of 50.^5,6 Patients are predisposed to systemic HTN, premature coronary artery disease (CAD), HF, ICH, or aortic rupture or AD.^1,7 Several factors likely contribute to aortic wall fragility in this patient’s CoA. Embryologically, CoA is thought to result from abnormal incorporation of ductal tissue into the aortic wall at the isthmus. In the “ductal sling” theory, the muscle-rich ductus arteriosus tissue encircles the aorta. After birth, constriction of this tissue leads to CoA, resulting in an inherently weakened segment of the aorta. ⁸ Our patient survived into his mid-40s with undiagnosed CoA, which is highly unusual, and his sentinel presentation was that of an imminently life-threatening AD for which he ultimately deferred surgical and endovascular intervention.

Although AD is a well-recognized complication of CoA, most reported cases involve the ascending aorta (Stanford type A), particularly in patients with a BAV.^9,10 Type B ADs are rare in this population, with fewer than 25 cases described in the literature.^11-17 The pathophysiology observed in our patient is similar to prior reports, in which chronic, upper-body HTN proximal to the CoA creates a high-shear stress environment. Simultaneously, intrinsic medial degeneration of the poststenotic aortic wall develops in response to collateral blood flow and predisposes the segment to intimal tearing. ⁶ In our case, the intimal tear originated just distal to the stenosed segment, which is a pivotal location that combines the accentuated proximal shear force and the attenuated poststenotic aortic wall vulnerability, to predispose this site to AD in patients with CoA. ¹² Even infants with CoA show cystic medial necrosis, suggesting a congenital aortopathy extending beyond a simple mechanical narrowing. ¹⁸ Furthermore, the hemodynamic disturbances of CoA with chronic HTN above the CoA and hypoperfusion below it can incite a complex inflammatory milieu within the aortic wall. Recent investigations have implicated an adventitial inflammatory cascade in the pathogenesis of ADs. Angiotensin II-driven signaling induces the production of interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) in the aortic wall, thereby recruiting macrophages and accelerating extracellular matrix degradation.^19-21 Experimental models have shown that knocking out IL-6 or the MCP-1 receptor markedly reduces the incidence of ADs. ²² Clinically, circulating IL-6 levels correlate with aortic dilation in patients with aortopathies, underscoring the role of inflammation in weakening the arterial media. ²³ Together, the embryologic presence of a ductal tissue “sling,” the acquired intrinsic medial degeneration, and inflammation-mediated matrix breakdown create a perfect storm of wall fragility, predisposing the CoA segment to AD.

Our patient’s history and examination exhibited a classical presentation, such as chronic, resistant HTN, a significant arm-leg blood pressure gradient, radio-femoral delay, and scapular systolic murmur, which are all hallmark signs of CoA in adults that can clinch the diagnosis. ⁶ Our case emphasizes the importance of a meticulous physical examination and blood pressure measurements in all 4 limbs in adults with unexplained, severe HTN.^7,24 Advanced imaging plays a crucial role in diagnosis and management. CTA is the modality of choice for acute presentation, as it rapidly confirms the presence of CoA and delineates any AD. MRA is a critical complement, providing a radiation-free evaluation of the extent of the dissection, lumen dynamics, and collateral flow.^25,26 Current guidelines recommend that all adults with CoA undergo periodic surveillance imaging with MRA or CTA surveillance, even after repair, to detect complications early.^7,24 In our patient, the combination of these instrumental imaging techniques enabled comprehensive anatomical assessment and planning for potential intervention.

Optimal management requires treating both the AD and the underlying CoA. In the acute phase, standard anti-impulse therapy is paramount, with aggressive control of blood pressure and heart rate through the use of intravenous BBs and vasodilators to reduce aortic shear stress and prevent the propagation of the AD.^7,24 Uncomplicated type B ADs are initially managed medically in most cases, as was done with our patient.^7,24 Once the patient is stabilized, attention turns to a definitive treatment of the CoA and any residual associated aortic pathology. In adults, thoracic endovascular aortic repair with a covered stent can be an excellent option, as it simultaneously excludes the false lumen and relieves the CoA stenosis. ²⁷ Endovascular stenting is not the first-line treatment in adult cases of CoA, and has been successfully used in CoA patients with ADs to promote aortic remodeling. ²⁸ Alternatively, open surgical repair, involving resection of the CoA with graft replacement of the dissected segment, may be required for complex anatomy or large aneurysm formation. ²⁹ A systematic review of CoA complicated by type B AD found no perioperative deaths and low complication rates with either surgical or endovascular approaches. ¹¹

Nevertheless, lifelong follow-up is essential, as 30% to 70% of patients develop persistent HTN despite successful CoA repair, and late complications such as aneurysm formation, re-coarctation, and recurrent ADs are well described.^30-32 Current American College of Cardiology/American Heart Association and European Society of Cardiology guidelines emphasize the importance of stringent blood pressure control and serial imaging at 6 to 12 months postintervention, followed by imaging every 1 to 3 years thereafter.^7,24

Conclusion

We describe a rare case of Stanford type B AD in an adult patient with unrepaired CoA and a trileaflet aortic valve. This case highlights the importance of considering CoA in adults with refractory HTN and discrepant peripheral blood pressure. Advanced imaging techniques, including CTA and MRA, are imperative for accurate diagnosis and treatment planning. Definitive management should be individualized but typically involves endovascular repair, which can address both CoA and AD simultaneously. Lifelong interval surveillance, including periodic imaging and blood pressure control, is essential to optimize long-term outcomes.