Multidisciplinary Surgical Management for a Pregnant Patient With Acute Type A Aortic Dissection

Introduction

Clinically, type A aortic dissection, as a kind of life-threatening cardiovascular emergency, is associated with high mortality and morbidity, especially for pregnant patients, mostly due to aortopathy such as aortic dilation [1]. This report highlights a successful surgical treatment for a pregnant patient with type A aortic dissection, without any severe complications. This case report has been reported in line with the Surgical CAse REport (SCARE) Criteria.

Case Report

A 37-year-old pregnant patient (G3P1), at the 37th week of gestation, was admitted to our hospital with a sudden severe pain in both chest and back without any improvements after conservative medical intervention. During pregnancy, blood pressure normally fluctuates between 140–151 mmHg and 81–90 mmHg, with a top level at 160/90 mmHg. However, on admission, our patient’s initial blood pressure was measured as 172/99 mHg, showing hypertension out of the normal range of pregnancy. Later, though, blood pressure in the same patient was remeasured as 80/51mmHg, which indicated an unstable hemodynamic. Fortunately, no more malperfusion-related symptoms were found. In accordance with a finding on contrast-enhanced computed tomography (CT), the diagnosis of singleton intrauterine pregnancy complicated by type A aortic dissection was confirmed (Figures 1, 2). A comprehensive assessment was initiated, and all lab test results were normal, including blood routine assay, liver and renal function, and coagulation status, and no abnormal wave changes were found in an electrocardiogram. Given that the intrauterine fetus was considered mature at the 37th week of gestation, after consultation with the obstetric department, we determined that the best course of action would be the simultaneous procedures of emergent cesarean section and repair of the type A aortic dissection. Related details of surgery were negotiated with the patient and her family members and written informed consent was obtained before the surgery.

Firstly, through cesarean section, an infant weighing 3230 g with Apgar scored 8.0 was delivered and transferred into the neonate department for further special treatment. Meanwhile, the ascending branch of the uterine artery was ligated with the aim to avoid uterine atony or potential massive bleeding during cardiopulmonary bypass.

Then, a composite aortic root replacement (Bentall procedure), total arch replacement, and antegrade deployment of a descending thoracic aortic stent graft were performed under an assist of cardiopulmonary bypass. Intraoperatively, 2 combined cannulation sites, femoral and left common carotid artery, were selected. Both aortic root aneurysmal dilation and severe aortic valve insufficiency were observed. A #23 valve-bearing vascular prosthesis was sutured on the aortic annulus. During the deep hypothermia cardiac arrest which lasted 30 min, with a flow rate of 5–8 mL/kg/min of cerebral perfusion at 24°C through selected antegrade cerebral perfusion via the left common carotid artery, a #24 thoracic aortic stent graft was initially placed into the descending aorta. Then, this stent was end-to-end anastomosed with a #26 4-branch aortic graft, arch, and stent. Sequentially, after deep hypothermia cardiac arrest, the innominate artery, left common carotid artery, and left subclavian artery were reconstructed and lastly, end-to-end anastomosis for aortic graft and prothesis was completed. The heart was declamped and recovered at 35°C and the cardiopulmonary bypass weaned at 37°C. Regular hemostasis and chest closure were continued.

Postoperatively, the patient was transferred into the cardiac intensive care unit (ICU) for further treatment and extubated on the second day. Based on the images during follow-up, it was indicated that a double-lumen had been present within the ascending aorta, thoracic aorta, and abdominal aorta, and that the blood supply of the left common carotid artery, left subclavian artery, celiac trunk, and superior mesenteric artery originated from the true and false lumens. The placed stent was correctly in position without outleakage of contrast agent (Figure 3). At the second week after surgery, both mother and infant were discharged without any adverse events. At the fourth month after surgery, the outcome for both mother and her baby is satisfactory without any cardiac, obstetric, or neurological complications.

Discussion

Naturally, during pregnancy, higher cardiac and vascular volume caused by pregnancy-associated physical changes, including fetoplacental circulation, enlarged uterus, changes in endocrine regulation, and increased circulation load, may potentially induce dilation of the aorta [2]. It has been demonstrated that the mortality of pregnant or postnatal patients with type A aortic dissection is more than 50% [3]. Hence, based on the results from a multicenter cohort study by Liu et al [4], emergent repair surgery of type A aortic dissection is needed when it occurs within any stage of pregnancy or in the postpartum period. However, the development of the fetus in the uterus should be taken into consideration before surgery. It has been found that, during pregnancy, compared with baseline, left ventricular stroke volume exceeds 30% and impact force from blood flow on the aortic wall increases as well; also, aortic wall pressure is higher due to compression from the pregnant uterus [5]. All these mentioned changes during pregnancy are associated with increased flow shear stress and aggravated damage to the aortic wall [6,7]. Moreover, secreted estrogen and progesterone at the early stage of pregnancy induce several structural changes which remodel both the tunica media and the tunica intima of the aortic wall [8].

Besides pregnancy, some types of hereditary connective tissue and vascular disease, vascular inflammation disorders, acquired heart disease, and cocaine abuse are also considered as independent risk factors for the occurrence of type A aortic dissection, among which Marfan syndrome is widely thought as the leading condition causing aortic dissection at an earlier age or stage during pregnancy due to potential preexisting pathological alterations of the aortic wall [9]. Currently, it has been confirmed that inherited connective tissue diseases including Marfan, Turner, and Ehlers-Danlos syndromes are characterized as a disruption of aortic structure contributing to the development and formation of an aortic aneurysm [10]. In a prospective study, the diameter of the aortic root plays a determinant role in predicting the outcomes for both the mother and neonate: if the diameter is <40 mm, the pregnancy will be able to tolerate the aortic aneurysm, with a satisfactory outcome; however, if the diameter increases to ≥40 mm, increased adverse events, including dilation and rupture of the aorta as well as type A aortic dissection, are seen [11]. Based on a study conducted by Nataf et al [12], pregnant patients with dilation of the thoracic aorta account for 79–89% of patients with type A aortic dissection and 11–21% of patients with type B aortic dissection. In a survey conducted by Yuan [9], Marfan syndrome and pregnancy are 2 predominant risk factors associated with aortic dissection. In pregnant patients with Marfan syndrome, Marfan-induced dissection can occur in all trimesters, especially in the last trimester; in contrast, among non-Marfan syndrome pregnant patients, aortic dissection occurs only in the third trimester.

Historically, for patients at an early stage of pregnancy, it has been recommended that the pregnancy be terminated and emergent surgery be performed immediately. In contrast, for pregnant patients at around 28 weeks gestation, surgery should also be performed as expected, but without terminating the pregnancy. In such cases, intrauterine changes should be monitored with caution with the aim to prolong the gestation period as long as possible. On the other hand, when pregnancy exceeds 32 weeks, intrauterine development of the fetus may be mature; therefore, a strategy for concomitant cesarean section and aortic repair surgery is the preferred option [13,14]. Meanwhile, non-surgical medical intervention for the prevention of aortic dissection is reasonable, such as the use of beta-blockers, which have a reliable record of safety and effectiveness during pregnancy, to release aortic wall stress and decrease the risk of aortic dilation [15]. Obstetrically, the main concern centers on the risk of hemorrhage caused by anticoagulants used within cardiopulmonary bypass. Hence, hysterectomy following cesarean section is suggested, with the aim to prevent major bleeding by anticoagulation [16]. In our case, once the diagnosis was confirmed through a series of clinical approaches, a comprehensive assessment involving obstetric and cardiovascular strategies was established individually in accordance with the actual demands of the mother and fetus. Based on the fact that, by the 37th week of gestation, the fetus is considered developmentally mature, the simultaneous procedures for cesarean section and repair of type A aortic dissection were selected as the surgical strategy. Moreover, the infant was delivered first, before the aortic repair surgery, so a femoral arterial cannulation was able to be manipulated with less difficulty. Besides ligation of the ascending branch of the uterine artery, regular anticoagulation management of cardiac surgery was also adopted. Currently, femoral and axillary arterial cannulation are mainly considered as the preferred feasible options. It has been demonstrated that, for these 2 cannulation approaches, there are no significant differences in adverse outcomes, including stroke incidence, mortality rates, and neurological complications [17]. Under emergency conditions, compared with axillary arterial cannulation, femoral arterial cannulation is more convenient and less time-consuming. Most importantly, in our center, effective medical systems have been established to optimize surgical strategy for both aortic dissection and gestation intervention.

Furthermore, in our case, under emergency conditions, contrast-enhanced CT was selected as the diagnostic imaging method for detection of the type A aortic dissection. Although contrast-enhanced CT has been considered the gold standard for type A aortic dissection diagnosis, some concerns for potential radiation damage to the fetus still exist, which limit its timely usage, leading to a possible delayed or mistaken diagnosis. However, nowadays, it has been recommended that, if clearly needed, a series of radioactive imaging tests, including CT and angiography, are appropriate when the aim is to confirm diagnosis [18]. Based on the current published literature, the radioactive dose is not associated with adverse events for the fetus, and for a pregnant patient with unstable circulation status, these techniques, including CT, are the most convenient and accessible diagnostic vehicles, and should be considered top priority choices [19,20].

Conclusions

In conclusion, the optimal treatment for pregnant patients with type A aortic dissection depends on various clinical factors and different indications. For pregnant patients ≥32 weeks, aortic repair surgery following cesarean section should be the primary recommendation, and the necessary protection for both mother and fetus should be emphasized. It is suggested that women with high risk factors receive special consultation before pregnancy. Once a diagnosis of aortic dissection has been confirmed, multidisciplinary management is also necessary, and an emergency intervention team including obstetric and cardiac experts should be activated immediately. In accordance with the type of aortic dissection and the gestation period, the optimal strategy for lowest mortality for both mother and fetus, as well as prevention of adverse events, must be carefully planned and carried out.