A dissection of the aorta proximal to its arch is a surgical emergency.1,2 Although the dissection flap in such cases is usually oriented along the long axis (LAX) of the aorta, in rare cases it occurs circumferentially and produces a so-called “intimo-intimal intussusception.”3,4 Here, the intimal flap collapses retrogradely in diastole, and systole produces antegrade propulsion.4 Depending on the proximity of the tear to the aortic valve (AV), the flap may repeatedly intussuscept through the valve itself and cause leaflet damage with each cardiac cycle.5
Fewer than 30 cases of circumferential type A dissection with intimo-intimal intussusception have been described since the original report by Hufnagel and Conrad in 1962.3 These have included defects of nearly all portions of the aorta, with and without prolapse through the AV.3–7 This abnormality’s similarity in presentation to acute coronary syndrome (ACS) and its unusual appearance on imaging are thought to contribute to the likelihood of mortality.4,5 Transesophageal echocardiography (TEE) has been identified as a potential gold standard for imaging in such patients.6,7
We submit this case to add to the body of literature on this topic and, we hope, to improve the management of this rare condition.
The patient in this case was contacted and consented to the publication of this report.
A 33-year-old woman with known Marfan syndrome presented to the emergency department after the sudden onset of severe substernal chest pain with associated presyncope, blurry vision, right-arm numbness, nausea, vomiting, and diaphoresis. On examination, she was afebrile and her arterial blood pressure and heart rate (HR) were 105/36 mmHg and 75 bpm in the left arm and 115/35 mmHg and 83 bpm in the right arm. The remainder of her cardiovascular and pulmonary examinations were noncontributory.
Initial workup included an electrocardiogram, which showed inferolateral ST depression, and laboratory values, which showed an elevated serum level of lactate but not of any cardiac enzyme. A portable chest radiogram showed cardiomegaly with a tortuous aorta and mild interstitial edema.
The patient underwent emergent thoracic computed tomography (CT) angiography approximately 30 minutes after presentation, which suggested the presence of a Stanford type A dissection involving the AV leaflets and the left main and right coronary arteries (Fig. 1, A and B).
The patient was sent to the operating room for emergent surgical repair. Rapid sequence induction using fentanyl, midazolam, and vecuronium was performed and an endotracheal tube was placed without difficulty. After induction, we inserted a radial intra-arterial catheter and an internal jugular central venous catheter, as well as a TEE probe.
Both 2-dimensional (D) and 3D TEE confirmed a complete circumferential dissection of the ascending aorta at the level of the sinotubular junction, with intussusception of the intima extending through the AV and into the left ventricle (Fig. 1, C–F; Supplemental Digital Content 1–4, Video 1–4, http://links.lww.com/AACR/A15, http://links.lww.com/AACR/A16, http://links.lww.com/AACR/A17, http://links.lww.com/AACR/A18).
Surgical intervention in this case involved placing the patient on cardiopulmonary bypass, replacing the aortic root with an ON-X™ mechanical valve (On-X Life Technologies, Austin, TX) and Vascutek™ (Vascutek, a Terumo Co., Inchinnan, Renfrewshire, Scotland) graft prosthesis, and brief circulatory arrest for hemiarch aortic reconstruction. The patient was separated from cardiopulmonary bypass without difficulty, and postbypass TEE revealed excellent functioning of the prosthetic AV. Six-month follow-up echocardiography showed a return to a normal left ventricular ejection fraction of 55% to 60%, and the patient was otherwise doing well.
As with most cases of aortic dissection, a positive clinical outcome in this case was contingent upon early diagnosis and quick operative intervention. Had this patient arrived unable to communicate her history of Marfan syndrome, it is very possible that her presentation could have been mistaken for ACS. In previously reported cases of aortic intimal intussusception, patients that were taken for emergent coronary angiography instead of the operating room have experienced unnecessary delays in appropriate care.5 While this patient’s medical history and young age were certainly helpful in excluding ACS, other indicators that pointed to the correct diagnosis (before imaging) included her widened pulse pressure and the absence of elevated cardiac enzymes. To our knowledge, this is the first reported case of intimo-intimal intussusception with signs of myocardial ischemia (chest pain with ST depression on electrocardiogram) in which the patient was not first taken for emergent coronary angiography and instead proceeded directly to the operating room. Lajevardi et al.5 and Yavuz et al.7 both describe cases in which patients were first evaluated for ACS and, while each patient survived, there were delays in appropriate treatment. Indeed, had our patient’s history of Marfan syndrome been unknown, she is likely to have undergone angiography as well.
This may also be the first reported use of both 3D CT and 3D TEE in the management of aortic intimal intussusception in a patient with acute type A dissection. In a recent publication, Sasaki et al.8 reported that 3D TEE was superior to other imaging modalities in the detection of coronary involvement. In our case, although we were unable to effectively visualize the extent of ostial involvement using either 2D or 3D TEE, 3D TEE was useful in fully characterizing the circumferential dissection and its interference with AV function. TEE in general, as compared to CT, proved to be a more specific imaging modality and allowed the surgeon to better plan for key elements of the operative repair involving the AV.
As with most type A dissections, the extent and nature of aortic pathology in this case was best determined using the midesophageal (ME) AV LAX and ME AV short axis (SAX) views.9 The ME AV LAX view (Fig. 1, E and F; Supplemental Digital Content 2–4, Video 2–4, http://links.lww.com/AACR/A16, http://links.lww.com/AACR/A17, http://links.lww.com/AACR/A18) clearly demonstrated complete obliteration of the sinotubular junction as well as a dilated aortic root and ascending aorta. In the same view, the dissection flap itself could be seen originating near the sinotubular junction and repeatedly prolapsing though the AV orifice in diastole. The severity of aortic insufficiency (AI) was determined using color flow Doppler and a jet height to left ventricular outflow tract diameter ratio. With an observed ratio of 1.0, the AI was classified as severe; a finding that contributed significantly to intraoperative decisions and management. The AV itself could not be seen in the ME AV SAX view due to obstruction by the circumferential intimal flap again seen prolapsing through the valve (Fig. 1, C and D; Supplemental Digital Content 1, Video 1, http://links.lww.com/AACR/A15). The transgastric mid-SAX view of the left ventricle showed hypokinesis of the inferior wall and inferoseptal wall, a regional wall motion abnormality suggestive of right coronary artery involvement. The upper esophageal aortic arch LAX view showed the dissection extending to the aortic arch and further guided the operative repair. All findings were consistent with type A dissection and the known aortic sequelae of Marfan syndrome. All views provided confirmation of the diagnosis first suggested by preoperative CT imaging and contributed significantly to both surgical and anesthetic management.
Type A dissections involving intimo-intimal intussusception present unique intraoperative challenges for the anesthesiologist, including the hemodynamic consequences and management goals for aortic dissection, aortic regurgitation, and myocardial ischemia. These goals often conflict and must be balanced. The primary goals for intraoperative hemodynamic management of aortic dissection are HR control and prevention of increased systolic blood pressure to limit the stress on the fragile aortic wall. This is commonly achieved with beta blockade. The primary goals in management of acute AI are promotion of forward cardiac output, achieved by preservation of preload and contractility, reduction in afterload reduction, and a moderate increase in HR. Increased HR and the resultant decrease in the diastolic interval reduce the regurgitant fraction and decrease the left ventricular end diastolic pressure, thereby improving subendocardial blood flow. The primary goals in management of myocardial ischemia are to maintain coronary perfusion pressure and limit increases in myocardial oxygen demand. Usually, this is accomplished with perioperative beta blockers and nitrates. However, myocardial ischemia that is caused by mechanical obstruction must be treated differently. In this case, in which the ischemia results from intermittent ostial occlusion by the intimal flap, and possibly coronary artery dissection, aggressive rate control, and nitrate therapy were not appropriate.
In cases where such hemodynamic paradoxes arise, optimal management can be elusive and challenging. Ultimately, we were able to avoid left ventricular failure by focusing management on the primary hemodynamic problem (in this case, AI) and limiting increases in left ventricular end diastolic pressure and afterload. Assessment with TEE with identification of the primary hemodynamic problem(s) were key elements of our successful management. E
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