Tetralogy of Fallot and Aortic Dissection: Implications in Management.

We present the case of a 61-year-old man with tetralogy of Fallot postrepair and mechanical aortic valve replacement with an aortic root/ascending/arch aneurysm with chronic type A aortic dissection. He underwent uncomplicated aortic root and total arch replacement. Continued surveillance for aortic aneurysm is necessary in the tetralogy of Fallot population. (Level of Difficulty: Intermediate.).

History of Present Illness

A 61-year-old man with a tetralogy of Fallot (TOF) complete repair (age 5 years) followed by a mechanical aortic valve replacement (age 38 years) presented to an outside clinic with progressive exertional dyspnea. He was afebrile with a heart rate of 80 beats/min, blood pressure of 129/79 mm Hg, and a respiratory rate of 16 breaths/min with oxygen saturation of 97% on room air; his body mass index was 26 kg/m2. Physical examination showed a median sternotomy scar and normal S1 and prosthetic S2 sounds with an early peaking grade 2 of 6 systolic murmur best heard at the left upper sternal border. He had 2+ palpable radial, femoral, and pedal pulses. He did not have a rub, gallop, peripheral edema, or elevated jugular venous pulsations.

Learning Objectives

To recognize that patients with tetralogy of Fallot and aortic dilation can develop aortic dissection.

To manage acquired cardiovascular risk factors in the tetralogy of Fallot population.

To promote collaboration between adult and pediatric cardiologists and cardiothoracic surgeons.

Past Medical History

The patient’s medical history included hypertension, hyperlipidemia, hemorrhagic stroke, central retinal artery occlusion, benign prostatic hypertrophy, and osteopenia. His social history was negative for tobacco use. His home medications included atorvastatin, losartan, verapamil, tamsulosin, and warfarin.

Differential Diagnosis

The differential diagnosis of exertional dyspnea in an adult patient with history of TOF surgical repair is broad. It includes pulmonary or tricuspid regurgitation, right heart failure, left ventricular heart failure with reduced or preserved ejection fraction, endocarditis, arrhythmia, and/or coronary artery disease.

Investigations

Transthoracic echocardiogram showed normal left ventricular systolic function with moderate concentric hypertrophy, normal right ventricular function, a mechanical aortic valve with a mean gradient of 22 mm Hg, and a small restrictive residual ventricular septal defect patch leak with left-to-right shunt. There was no right ventricular outflow tract obstruction and trace pulmonary and tricuspid regurgitation. Also shown was a dilated ascending aorta measuring 6.1 cm. A computed tomography (CT) scan of the chest revealed an aortic root, ascending aorta, and arch aneurysm. The ascending aorta measured 6.9 cm in largest dimension compared with 5.3 cm on a scan in 2016. The patient was therefore referred for surgical evaluation. No other studies were performed. A repeat CT scan of the chest, abdomen, and pelvis done 10 days later for surgical planning revealed a Stanford type A aortic dissection that extended from the aortic root and ended in the arch (Figure 1). A single coronary artery arose from the left sinus with a retroaortic course of the right coronary artery (Figure 2).

Figure 1

Preoperative Computed Tomography Scan Showing Stanford Type A Aortic Dissection Extending From the Aortic Root to Arch

Figure 2

Preoperative Computed Tomography Scan Showing Single Coronary Artery From the Left Sinus With a Retroaortic Right Coronary Artery Course

Management

General anesthesia was induced and neuromonitoring used. A third time redo sternotomy was performed. Cardiopulmonary bypass was initiated, and the patient cooled systemically to 24 °C. A large primary intimal tear was identified within the aortic root (Figure 3). The mechanical valve was removed, and an aortic root replacement performed (bioroot: 29-mm Edwards Lifesciences INSPIRIS RESILIA aortic valve sewn inside a 32-mm Dacron graft). The single coronary artery was reimplanted (Figure 4). A total arch replacement (zone 2) was performed by using unilateral selective antegrade perfusion for neuroprotection via an axillary artery perfusion graft with stable head oxygen saturations with near-infrared oximetry (Figure 5). A branched prosthesis with separate reimplantation of the innominate and left carotid arteries allowed us to excise the aneurysmal and dissected aorta entirely. The branch technique provides several advantages over the island technique, including that: 1) the anastomoses are performed where the arteries are free of dissection and atherosclerosis; 2) the pathologic arch tissue can be completely excised; and 3) bleeding from the arch vessel anastomoses can be more easily controlled.

Figure 3

Intraoperative Photograph Demonstrating Chronic Type A Dissection With True and False Lumens

Photograph demonstrating chronic type A dissection with true (left) and false (right) lumens.

Figure 4

Intraoperative Photograph Demonstrating the Aortic Root With Previous Mechanical Aortic Valve and Single Coronary Artery Ostium

Figure 5

Postoperative Image of Redo-Aortic Root and Total Arch Replacement

The patient was extubated on postoperative day 1, had an uneventful postoperative recovery, and was discharged home on postoperative day 8. A repeat CT scan showed the newly replaced aorta without complications (Figures 6 and 7).

Figure 6

Postoperative Computed Tomography Scan Showing View of Great Arteries After Total Arch Replacement

Figure 7

Postoperative Computed Tomography Scan Showing Posterior View of Total Arch Replacement and Reimplanted Coronary Artery

Discussion

Although TOF is considered a disease of the right side of the heart and right ventricular outflow tract, aortic dilatation is present in at least 20% of patients with repaired TOF. Aortic dilation can result from the increased aortic flow due to right-to-left shunting at the ventricular septal defect before repair, but it is not known what causes further dilation after TOF repair. However, a retrospective autopsy study showed higher grade histologic changes (including the presence of medionecrosis, fibrosis, cystic medial necrosis, and elastic fragmentation) in the ascending aortas of a cohort of TOF patients compared with normal control subjects. Similarly, a subsequent prospective study of aortic dilation in TOF found that 75% of patients had histologic abnormalities of the aortic wall, including elastic tissue fragmentation, increased ground substance, medionecrosis, muscle disarray, and fibrosis. A recent analysis of hospitalized TOF patients from the National Inpatient Sample found 11 cases of aortic dissection with mortality of 45%. In addition, 6 case reports of aortic dissection in TOF (Table 1) have been reported in the literature.5, 6, 7, 8, 9, 10

Table 1

Literature Review of Prior Case Reports of Aortic Dissection in Tetralogy of Fallot

First Author, Year	Age, Presentation	Acute or Chronic Location and Size Histology	Treatment
Kim et al,5 2005	30-year-old man with chest pain	Acute	Bentall procedure
		Ascending aorta 7 cm
		Fibrous, thrombotic exudates. No cystic medial degeneration
Rathi et al,6 2005	36-year-old man with chest pain	Acute	Not available
		Ascending aorta 9.3 × 8.3 cm
Konstantinov et al,7 2010	18-year-old man with 22q11 deletion syndrome with chest pain	Acute	Valve sparing
		Ascending aorta 6 × 7 cm	aortic root replacement was performed with a 30-mm Valsalva graft
Wijesekera et al,8 2014	60-year-old man with chest pain and dyspnea	Acute	Bentall procedure
		Ascending aorta 5.5 cm (4.9 cm ascending aorta 2 y earlier)
Jariwala et al,9 2017	30-year-old man unrepaired with dyspnea and back pain	Subacute NA	22-mm interposition graft in the ascending aorta was performed
Chow et al,10 2020	35-year-old man with chronic chest discomfort over past months	Acute	Bentall
		Ascending aorta 8.8 × 7.6 cm (4.8 × 5.1 cm ascending aorta 3 y prior [stopped losartan])
		Myxoid generation and focal calcification, mild cystic medial degeneration

Unlike aortopathies associated with bicuspid aortic valve, in which the 2020 American College of Cardiology valvular heart disease guidelines establish a diameter of >5.5 cm as a Class I indication for aortic root replacement (or a diameter of 5-5.5 cm as a Class IIb indication if surgery is being performed at a Comprehensive Valve Center), there are no statements in the 2018 American College of Cardiology/American Heart Association Adult Congenital Heart Disease guidelines on the management of the dilated aortic root in TOF. Although a dilated aortic root is not uncommon in the adult with repaired TOF, conservative management and observation in the setting of aortic root dilation with conotruncal defects such as TOF are typically recommended.

Age >60 years, male sex, and hypertension are associated with aortic dissection in the TOF population. Perhaps not surprising, our patient exhibited all 3 risk factors. His initial repair was performed at a later age, which has been associated with a dilated aortic root. As the TOF patients continue to age, they are susceptible to acquired atherosclerotic cardiovascular risk factors. These acquired comorbidities may serve as a “second hit” to the increased aortic flow before repair and intrinsic aortic medial aortopathy and lead to further dilatation of the aorta. Thus, in the presence of adult acquired comorbidities such as hypertension and atherosclerosis, one may consider aortic root replacement at a diameter of ≥5.5 cm and at 5.0 to 5.5 cm in the setting of re-operation for aortic or pulmonary valve replacement in TOF.

This case will make us consider more frequent advanced imaging surveillance and earlier referral for prophylactic aortic root replacement in the setting of a patient with a conotruncal lesion and significant cardiovascular comorbidities (eg, hypertension). Importantly, immediate surgical repair is recommended in the setting of acute type A dissection. Although rupture and cardiac tamponade may be reduced in patients with previous sternotomies due to mediastinal adhesions, acute aortic regurgitation and coronary artery dissection or occlusion account for the high mortality rate in untreated acute type A dissection. The International Registry of Acute Aortic Dissection reports that medical therapy alone has a higher mortality rate compared with surgery (in-hospital and intermediate-term) even in patients with prior cardiac surgery, supporting an operative strategy for acute type A dissection. Lastly, current guidelines for surgical repair in chronic type A dissection (>14 days) are based on degenerative aneurysm recommendations (5.5 cm). A recent study by Kim et al reported increased adverse aortic events in 82 patients with chronic type A dissections over 19 years, noting a worse prognosis in dissected vs nondissected ascending aneurysms. We also believe that the natural history of aneurysmal chronic type A dissection is more precarious than nondissected ascending aneurysm and therefore recommend surgery at a lower aortic dimension (5 cm).

Follow-up

At the 12-month follow-up visit, the patient’s blood pressure is well controlled on losartan and metoprolol.

Conclusions

We present the case of a 61-year-old man with TOF status postrepair with comorbidities of hypertension and hyperlipidemia who presented with aortic dissection. This is the seventh case reported of aortic dissection in this population. Serial surveillance of aortic aneurysms in TOF is necessary, and it would be reasonable to consider replacement of the aorta in TOF patients with an ascending aorta or aortic sinus with a diameter ≥5.5 cm.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.