Stanford Type B Aortic Dissection in a Patient With Osteogenesis Imperfecta: A Case Report

Introduction

Connective tissue disorders are a well-established risk factor for type B aortic dissections due to the compromise in connective tissues’ structural integrity, with the most commonly implicated genetic disorders being Marfan syndrome, Ehlers-Danlos syndrome, and Loeys-Dietz syndrome.^1,2 Osteogenesis imperfecta (OI) is a rare group of disorders caused by defects in type-1 collagen synthesis. ³ This results in defects in collagen-rich organs such as the skin, eyes, ears, teeth, skeleton, and vascular walls. The most common cardiovascular abnormality associated with the condition is aortic regurgitation and aortic root disease. ⁴ Despite weaknesses in vascular wall strength, there have been very few cases of reported aortic dissection in the literature. This article presents the third case of a Stanford Type B aortic dissection in a patient with OI, and the second case in a female patient. ⁵

Case Report

A 69-year-old female presented to a peripheral hospital with the sudden onset of epigastric pain radiating to the back. Her medical history was significant for OI, chronic lymphocytic leukemia, pituitary adenoma, which had been resected, hypertension, and hypercholesterolaemia. She was a nonsmoker and did not have a family history of aortic dissection or aneurysmal disease. As a result of her underlying OI, the patient had also suffered from a previous retinal detachment and multiple low-impact fractures. She had been diagnosed on genetic testing with a variant in the COL1A1 gene, and clinically was of short stature and had signs of dentogenesis imperfecta. The patient examined well, with a soft and nontender abdomen, and a full complement of palpable peripheral pulses, including bilateral radial, femoral, popliteal, and pedal pulses. There was no radio-radial or radio-femoral delay. Computed tomography angiogram (CTA) demonstrated an uncomplicated Stanford Type B aortic dissection extending from the distal thoracic arch to the level of the right common iliac artery. The maximum aortic diameter at the mid descending thoracic aorta measured 31.5 mm with evidence of thrombosis of the false lumen (Figure 1). The patient did not have any signs or symptoms of malperfusion to her visceral organs or lower limbs.

OPEN IN VIEWER

Figure 1.

Axial image of contrast-enhanced computed tomography of the thoracic aorta demonstrating the dissection and maximal aortic luminal diameter of 31.5 mm.

Initial management was undertaken with anti-impulse therapy using intravenous beta-blockade with labetalol, with strict heart rate targets of less than 60 beats per minute and systolic blood pressure lower than 120 mmHg. The patient was weaned to oral beta-blockers and antihypertensive agents, including metoprolol and prazosin, to maintain heart rate and blood pressure targets. The patient underwent an interval CTA 72 hours following presentation to assess for extension of her dissection, as well as complicating features—neither of which were present on this study. Incidentally, bilateral pleural effusions were noted on this repeat study, which were not present on the initial CT. The effusions were considered reactive in the setting of acute dissection, and given that the patient did not report any respiratory symptoms or have any oxygen requirements, they were managed conservatively with surveillance chest X-ray demonstrating resolution within a week.

The patient was discharged from the hospital following a 10-day stay to ensure adequate blood pressure and heart rate control. At follow-up 6 weeks after her initial presentation, interval CTA demonstrated expected remodeling of the false lumen without aneurysmal changes or increase in the extent of the dissection. The patient continues to be asymptomatic, with planned CTA at 3 and 6 months demonstrating no further changes. She remains monitored with annual imaging to monitor for aneurysmal degeneration, and an outpatient blood pressure target of less than 120 mmHg systolic, managed with regular home blood pressure monitoring, primary care, and specialist input.

Discussion

OI is a rare heterogeneous connective tissue disease characterized by abnormalities in type-1 collagen production. ³ The COL1A1 and COL1A2 genes encode the 2 alpha-1 and single alpha-2 polypeptide chains respectively within the type-1 collagen protein. OI is further classified into 4 subtypes based on genetics and the clinical presentation. ⁶ Type 1 is the most common subtype of OI and has an autosomal dominant inheritance pattern. It presents with a mild clinical phenotype characterized by bone fragility and blue sclerae, the former of which was present in our patient. Types 2 and 3 tend to be more severe and result in a shortened lifespan. Type 4 is similar to type 1, except that the classical blue sclerae are often absent.

Unlike patients with other connective tissue diseases such as Marfan syndrome and Ehlers-Danlos syndrome, aortic dissection in patients with OI is rare.^4,7 Cardiovascular manifestations are often clinically insignificant, with the most common cardiovascular abnormality being aortic root dilatation. Aortic and mitral regurgitation are the most common valvulopathies implicated in OI. There have only been 2 cases reported of descending aortic dissection (Stanford Type B).^5,8 In addition, only 2 females with OI have been reported to have any type of aortic dissection, one of which had a type B dissection. ⁵

Management of uncomplicated type B aortic dissection in patients with OI should be similar to contemporary management of the disease. Strict anti-impulse control with permissive hypotension and bradycardia to avoid physical stress on the aortic wall should be achieved using intravenous beta-blockade.^9,10 Interval aortic imaging to assess extension of the dissection within 72 hours of hospital presentation should be undertaken, with definitive surgical management being undertaken in the emergent setting only if necessary. Surgical intervention can be performed using either endovascular or open surgical approaches. ¹¹ With approximately 60% of all patients with type B aortic dissection developing aneurysmal growth within 5 years of onset, the likelihood of patients with OI and aortic dissection eventually requiring surgical repair is high. ¹² Arterial tissue strength in patients with OI is friable due to a lack of connective tissue strength, and therefore, when undertaking open surgical repair, the use of meticulous suture technique with fine needles and reinforcement with Dacron strips, pledgets, or surgical glue is often necessary. ⁸ Aortic repair and reconstruction in patients with OI has been performed in emergency situations for type A dissections in the literature and has been associated with major bleeding complications and high mortality rates.^5,8,13-15 In type B aortic dissections, one case report has outlined the challenges faced with successful open repair of the descending aorta in a symptomatic patient—undergoing a thoracotomy and subsequent persistent intrathoracic hemorrhage during his immediate postoperative course. ⁸ Thoracic endovascular aortic repair (TEVAR) is increasingly employed in the management of acute complicated type B aortic dissection; however, its role in patients with OI remains unclear. ¹⁶ There is no published data on patients undergoing endovascular repair with OI, but data from patients with other heritable connective tissue diseases such as Marfan’s and Ehlers-Danlos syndrome suggest a heightened risk of long-term unfavorable outcomes in aortic evolution with TEVAR being associated with retrograde dissection and endoleak, potentially due to the increased fragility of the aortic wall.^17,18 In our case, given the patient’s clinically stable presentation and uncomplicated dissection, we opted for conservative management, which aligns with current best practice while avoiding the potential hazards of endovascular intervention in the context of underlying connective tissue fragility.

Data surrounding long-term outcomes of patients with aortic disease and OI is scarce, largely due to the rarity of OI. Nonetheless, it would be prudent to ensure serial monitoring of aortic disease in this subset of patients with interval CT aortograms or echocardiograms if assessing the ascending aorta. Vigorous control of hypertension with the use of beta-adrenergic blockade to slow aortic dilatation and ultimately avoid the need for open repair is essential in the outpatient setting, given the high rates of complication and mortality. ⁹

Conclusion

Type B aortic dissection is a rare complication of OI. We present the third known case, and only the second involving a female patient. Management of this patient cohort should prioritize strict anti-impulse therapy and close outpatient surveillance. Given the inherent connective tissue fragility in patients with OI, any open or endovascular intervention should be performed with extreme caution, as these patients are at increased risk of perioperative morbidity and mortality. This case highlights the need for ongoing vigilance and personalized management strategies in patients with OI presenting with acute aortic pathology.