Sinus of Valsalva Aneurysms: A Review with Perioperative Considerations

Abstract

The sinuses of Valsalva are outpouchings in the aortic root just distal to the aortic valve that serve several physiologic functions. Aneurysm of this segment of the aorta is quite rare and infrequently encountered in clinical practice. Due to the rarity of sinus of Valsalva aneurysms, there is lack of controlled trials and most of the literature consists of case reports and series. Here, we review the currently available literature to discuss the anatomy and normal function of the aortic root as well as disease pathology and diagnostic imaging considerations. Utilizing reported cases we will also discuss considerations for cardiac anesthesiologists in the perioperative period.

Introduction

Sinus of Valsalva aneurysms (SVA) represent a rare condition in which there is dilation of one or more of the three aortic sinuses that form the connection between the aortic valve and the ascending aorta. Although the true prevalence is unknown, autopsy studies indicate that SVAs occur in less than 0.1% of the general population¹ and are found in approximately 0.2% of patients undergoing open cardiac surgery in Western countries,^2,3 with men being more commonly affected. Reported incidence is up to five-fold higher in Asian populations,⁴ likely related to differences in genetic composition.^5,6 Due to the anatomic location of the sinus of Valsalva and their physiologic function, SVAs can have significant clinical consequences in both the unruptured and ruptured state; although small, unruptured SVAs are generally found only incidentally. Here, we will review the underlying anatomy and physiology of the sinuses of Valsalva as well as pathologic development of SVAs and current management guidelines. While multiple modalities currently exist to definitively diagnose a SVA, a high index of clinical suspicion is necessary as this pathology is quite rare.¹

Sinus of Valsalva Anatomy and Physiologic Function

The sinuses of Valsalva refer to three outpouchings of the aortic root that lie between the aortic annulus and the sinotubular junction. Each sinus is associated with one of the semilunar aortic valve cusps and is named according to this association, such that there is a right, left, and non-coronary sinus of Valsalva. In relation to other cardiac structures, the right sinus of Valsalva sits in close apposition to the tricuspid valve and right ventricular outflow tract (RVOT); the left sinus is adjacent to the left ventricular free wall, anterior mitral leaflet, and transverse sinus; and the non-coronary sinus is adjacent to the interatrial septum, anterior mitral leaflet, and right atrium (Figure 1). Typically, the right sinus is the largest of the three in volume, and the left is the smallest.⁷ The normal range for Sinus of Valsalva diameter is 3.0 ± 0.3 cm for women and 3.4 ± 0.3 cm for men. When indexed for body surface area (BSA), normal values are 1.7 ± 0.2 cm/m² and 1.8 ± 0.2 cm/m² for women and men, respectively.^8–11 The coronary arteries arise from within the sinuses in most individuals, although the coronaries can arise either at the level of the sinotubular junction or above in the ascending aorta in a small fraction of individuals.^12–16

Figure 1.

Diagram illustrating the anatomic relationships between the sinuses of valsalva and adjacent structures. Arrows illustrate common routes of rupture into the right ventricle, right atrium, pericardium, and left atrium

Traditionally, it was thought the sinuses of Valsalva served to prevent occlusion of the coronary arteries with opening of the aortic valve. Fluid dynamic studies, however, have shown that these sinuses play other important physiologic functions. For instance, swirling of blood into the sinuses during systole allows for more complete valve opening, reducing the turbulence and pressure gradient across the valve,^17,18 as well as promoting efficient and coordinated aortic valve closure at end systole¹⁹ and increasing coronary blood flow.²⁰ This has been borne out in clinical studies showing preservation of the sinuses during aortic root surgery leads to maintenance of normal leaflet timing, leading to reductions in leaflet stress.^21,22

Etiologies

SVAs fall under two broad categories of either congenital or acquired. SVAs that are congenital in origin generally arise due to incomplete fusion of the aortopulmonary septum with the interventricular septum,²³ resulting in weakness at the junction of the aortic media and annulus fibrosus.²⁴ This weakness is prone to dilation, typically a single sinus, which continues to expand based on Laplace’s Law. Most commonly (65–85%) the right sinus is involved, with the non-coronary sinus (10–30%), and the left sinus being rarely involved.²⁵ The predilection for the right and non-coronary sinuses are thought to be related to their embryologic origin as the point of fusion of the aortopulmonary and interventricular septae, with incomplete fusion leading to relative weakness. Wall stresses are also higher in the fully developed right and non-coronary sinuses as compared to the left.²⁶ As consistent with their developmental origin, congenital SVAs are associated with ventricular septal defects (VSD) in 60% of patients, typically membranous type in the Western population²⁷ and supracristal in Asian populations.⁴ Other associated cardiac anomalies include bicuspid aortic valve in up to 10% of patients²⁸ and less commonly atrial septal defect, aortic coarctation, and pulmonic stenosis, subaortic stenosis, and patent ductus arteriosus.^29–35

SVAs can also have acquired origin, usually also relating to connective tissue damage. For example, infectious causes such as syphilis,¹ tuberculosis, and bacterial endocarditis³⁶ have all been described. Atherosclerosis³⁷ and cystic medial necrosis³³ can contribute as well, as can vasculitic diseases such as Takayasu^38,39 or Behcet’s.⁴⁰ Acquired SVAs can also have iatrogenic origin, with injury received during trauma, aortic valve replacement, or ventricular septal defect closure all having been described.^41–43 Although connective tissue disorders like Marfan, Loeys-Dietz, or Ehlers Danlos often have dilated Sinuses of Valsalva, they are typically symmetrical, involving the entire root, and perhaps would be better classified as aortic root aneurysms.²⁵

Clinical Manifestations and Diagnosis

Generally, small, unruptured SVA are asymptomatic and are only incidentally found.^30,31 However, given the central location the sinus of Valsalva occupies, as the aneurysm begins to expand, it can encroach on vital structures causing coronary ischemia,^44–49 left^50–52 and right^50,53–59 ventricular outflow tract obstruction, and cardiac conduction abnormalities, including ventricular arrhythmias and complete heart block (Figure 1).^50,60–62 Distortion of cardiac anatomy also leads to valvular dysfunction that includes aortic insufficiency in 20–30% of patients,^25,63 and can also include tricuspid insufficiency or stenosis.⁶⁴ The most common location for rupture is into the right ventricle (RV) in 60% of cases, right atrium in 30% of cases, and occasionally into the left atrium, left ventricle, pericardium, interatrial septum, interventricular septum, and pulmonary artery.^{28,33,65–69} Upon rupture of the aneurysm, patients can report sudden onset of non-specific symptoms, including fatigue, dyspnea, chest pain, and palpitations.^28,35,70 Depending on fistula size and location, symptom severity can range from mild to hemodynamic collapse. On physical examination, a continuous “machine” or “mechanical” sounding murmur can be auscultated that is generally superficial and is associated with a palpable thrill on the precordium.^28,31,71 In addition, findings associated with congestive heart failure may be present (i.e., pedal edema, jugular venous distension, rales, hepatomegaly)³¹ due to right-sided volume overload caused by left-to-right shunt through the ruptured segment.

As in physical examination, no specific serum studies have been determined that aid in diagnosis of SVA. Although electrocardiograms (EKG) are relatively fast, inexpensive, and non-invasive diagnostic tools, rupture can produce a wide array of clinical presentations and complications, thus findings are inherently varied and likely not useful in definitive diagnosis.³¹ Similarly, chest radiographs are inadequately sensitive or specific to be useful in diagnosis,^72–74 although findings of a widened mediastinum or increased density to the right of the caval shadow can be seen in these patients.^30,74 Because of this, efforts have shifted to more advanced diagnostic techniques, including transthoracic echocardiography (TTE) (Figure 2a), transesophageal echocardiography (TEE) (Figure 2b), multi-detector and EKG-gated computed tomography (CT), coronary angiography, and cardiac magnetic resonance imaging (CMR). While pertinent details to sinus of Valsalva imaging are discussed below, Xu, et al⁷⁵ have recently published an in-depth review pertaining to the various modalities of imaging these aneurysms as well as potential advantages and disadvantages.

Figure 2.

Examples of two different SVAs seen on TTE and TEE respectively. (a) Parasternal long axis view on TTE demonstrating a non-coronary cusp (NCC) SVA, denoted by the asterisk (*), as it impinges on the left atrium (LA). This view allows concurrent assessment of the right ventricle (RV), left ventricle (LV), ascending aorta (Asc Aorta), and LA. (b) Mid-esophageal aortic valve short-axis view on TEE demonstrating a right coronary cusp (RCC) SVA, denoted by the asterisk. This view allows evaluation of the right atrium (RA), LA, and main pulmonary artery (PA).

As discussed above, the dimensions of the aortic root depend on age, gender, and body surface area. It is generally accepted that two standard deviations above the population mean (or above 95^th percentile) constitutes abnormal enlargement.^8,74,76 Based on the values of normal aortic root diameter presented earlier, current guidelines^72,73,76 suggest that dilation beyond 3.6 cm and 4.0 cm, respectively, is abnormal. While it is well-known that normal aortic root measurements do increase with both age^9,10,74,77 and body size, there are no exceptions made for these factors in current guidelines. Modern advancements in ultrasound technology have made TTE a sensitive (93.9–95.5%), and specific (99.9%) method of diagnosis, with a positive predictive value between 93.8–95.4% based on current literature,^72,78 in addition to being able to simultaneously inspect and quantify cardiac function and potential valvulopathy. TTE enables rapid and adequate assessment of the aortic root and proximal ascending aorta at bedside⁷⁶ and has been recommended as a primary imaging study in acute aortic syndromes.^73,76,79 The aortic root can be well visualized in the parasternal long axis view with measurement of the diameter being made perpendicular to the long axis of the aorta at end diastole using leading edge-to-leading edge distance. Due to the relative motion of the aortic root relative to the cursor throughout the cardiac cycle (i.e, the root being displaced towards the apex during systole and rebounding more superiorly during diastole), M-mode has been shown to consistently produce smaller measurements (approximately 2 mm smaller when compared to two-dimensional echocardiography) of the aortic root.⁸ Therefore, two-dimensional echocardiography using leading edge-to-leading edge convention is preferred for measurement⁸⁰ over M-mode echocardiography. In the setting of SVA rupture, color Doppler will show a continuous turbulent flow between the aneurysm and the receiving chamber (Figure 3). Moreover, a classic “windsock” appearance has been described on echocardiography in the cases where the ruptured segment is a large portion of the aneurysm. Interestingly, this “windsock” will appear to expand and contract throughout the cardiac cycle as flow through the ruptured segment increases and decreases.⁷⁵

Figure 3.

TEE imaging of a ruptured SVA. (a) Mid-esophageal aortic valve long-axis view on intraoperative TEE demonstrating a RCC SVA which has ruptured into the right ventricular outflow tract (RVOT) as denoted by the asterisk (*). (b) Color Doppler has been applied to the image in (a) showing turbulent flow across the ruptured SVA.

Spectral Doppler measurements can show diastolic flow reversal in the aorta (Table 1), depending on the size of the ruptured aneurysm and the flow across it, as well as continuous high-velocity flow across the aneurysm with accentuation of the waveform in diastole. In contrast, a VSD, which is commonly coexistent, will show a high-velocity jet in systole with a low-velocity jet in diastole. A potentially challenging situation is when aortic insufficiency is coexistent with a VSD, whose diastolic flow pattern can mimic a ruptured SVA. In this case, the Doppler waveform will start in mid-diastole and gradually increases until the end of the diastolic period. In contrast, in the setting of aortic regurgitation, the Doppler waveform generally begins with diastole and decreases in a decrescendo.⁷⁵

Table 1.

Echocardiographic findings in ruptured sinus of Valsalva aneurysm versus potential confounding pathologies

	Sinus of Valsalva Aneurysm	Aortic Insufficiency	Ventricular Septal Defect
Aortic Root Dilation	Yes, generally asymmetric	Possible, generally symmetric	No
Color Doppler	Continuous turbulent flow	Turbulent flow during diastole	Turbulent flow during systole
Spectral Doppler	Continuous high-velocity jet with diastolic accentuation	High-velocity jet during diastole	High-velocity in systole, low Velocity in diastole
Shunt Timing	Mid-diastole with increasing velocity	Early diastole with decrescendo	Systole

Similarly, TEE can be a useful tool in conjunction with other diagnostic modalities, but is generally not indicated as a primary SVA imaging study.^75,76 Due to the proximity of the esophagus to the aorta, high-resolution images of the aortic root and sinus of Valsalva are obtainable on TEE imaging, mainly in the mid-esophageal aortic valve long axis and mid-esophageal aortic valve short axis views. Similar echocardiographic findings will be demonstrated as described above. The main drawbacks to this method as an initial diagnostic is the necessarily invasive nature (i.e., inserting the echocardiogram probe into the esophagus) as well as the need to administer sedation in a potentially unstable patient and the sequelae from the hypnotic agents used (i.e., need for monitoring, airway control, hemodynamic control). TEE does have an essential role during intervention and is the imaging study of choice,⁷⁵ with more detail discussed later in the review.

Multidetector cardiac computed tomography (MDCT) is another commonly used imaging modality which can be used in the diagnosis of SVA and has been recommended as the primary imaging study in some guidelines, including the Canadian Cardiovascular Society (CCS) guidelines.⁷⁹ MDCT is also a rapid method of diagnosis, able to acquire full data sets in a single breath hold,⁷⁵ but does require transport to the scanner, which might be precluded in the setting of ongoing interventions and patient status. Measurement of sinus diameter is made by the sinus-to-sinus convention in the plane of the aneurysm, perpendicular to the long axis of the aorta at end diastole.⁷⁴ The diameter is measured from the aneurysmal sinus to the opposite sinus with the largest diameter reported for all three cusps. For MDCT, this measurement is from external edge-to-external edge (i.e., this includes the diameter of the vessel wall). Studies comparing TTE and MDCT have shown good correlation,^81,82 although measurements obtained from echocardiography are generally smaller⁸³ as they do not generally include the aortic wall. While values specific to sinus of Valsalva imaging are not available, it is generally thought that MDCT has sensitivity and specificity approaching 100% in diagnosing aortic disease.⁷³ In addition to evaluation of the aortic root, MDCT can provide rapid evaluation of the entirety of the aorta, which is generally not possible with TTE or TEE alone, making it a complementary diagnostic tool in acute aortic syndromes. Moreover, complications from SVA rupture including chamber compression or dilation can be assessed by MDCT; in contrast, aortic insufficiency and coexisting structural defects, such as other valvular abnormalities, patent foramen ovale, or small atrial septal defect, cannot be excluded using this modality.⁸⁴ Other considerations include the need for iodinated contrast agents and radiation exposure, although advances in technology and image post-processing have significantly lowered exposure.⁷⁵

Lastly, CMR imaging can be an ancillary imaging modality for identifying SVA and its complications. In contrast to MDCT, CMR can provide assessment of cardiac function, including pulmonary:systemic blood flow ratio and aortic insufficiency, as well as being more sensitive in detecting thrombi in the aneurysmal sac. Moreover, because reliable imaging of the aortic root is achievable without intravenous contrast, two of the largest disadvantages to MDCT (i.e., radiation exposure and need for contrast medium) are avoided. CMR is limited by its lower spatial resolution (compared to MDCT), much longer acquisition times, as well as accessibility and expertise.⁷⁵ In addition, implantable cardiac electronic devices remain an issue in terms of safety and quality. Although devices are being produced that are MR compatible, devices with fractured, epicardial, or abandoned leads remain a contraindication to MR imaging.⁸⁵

Indications for Intervention and Surveillance

It is clear that in the case of ruptured or unruptured, symptomatic aneurysms, definitive intervention is indicated. Specific guidelines for unruptured, asymptomatic SVA are lacking, however. In general, it is accepted practice to follow guidelines for repair of aortic root aneurysms.^32,75 The 2010 American Heart Association (AHA) Guidelines on Thoracic Aortic Disease⁷² specifies that surgical repair is indicated in asymptomatic patients without familial aortopathy, connective tissue disease, or bicuspid aortic valve who present with an aortic root aneurysm greater than 5.5 cm (Class I Recommendation, Level of Evidence C); both 2014 European Society of Cardiology (ESC; Class IIa Recommendation, Level of Evidence C) and Canadian Cardiovascular Society (Strong Recommendation, Moderate-Quality Evidence) guidelines agree with this cutoff.^73,76 In the setting of associated genetic disorders (i.e., Marfan, Ehlers-Danlos, Turner, Loeys-Dietz, familial aortopathies), lower thresholds are utilized to recommend surgical intervention (Table 2).^72,73,79 While the presence of bicuspid aortic valve in the setting of aortic root aneurysm has traditionally lowered the threshold to operative intervention due to the altered histology and mechanical properties of the aorta in these patients, since 2010 the AHA has published revised guidelines specifically concerning these patients. The guideline states that for asymptomatic patients with a bicuspid aortic valve, there is currently not enough evidence to suggest lowered threshold for operative intervention, meaning that the cutoff for operative intervention is 5.5 cm.⁸⁶

Table 2.

Indications for intervention on sinus of Valsalva aneurysms based on size of the aneurysm

	ACCF/AHA Guidelines (2010)	ESC Guidelines (2014)	CCS Guidelines (2014)
Degenerative	5.5 cm	5.5 cm	5.5 cm
Bicuspid Aortic Valve	5.5 cma	5.0 cm	5.0–5.5
Marfan Syndrome	4.0–5.0 cm	5.0 cm	5.0 cm
Other Genetic Syndromesb	4.0–5.0 cm	—	4.0–5.0 cmc
Concomitant Cardiac Surgery	4.5 cm	4.5 cm	—
Annual Growth Rate	0.5 cm/year	0.3 cm/year	0.5 cm/year

Abbreviations: ACCF, American College of Cardiology Foundation; AHA, American Heart Association; ESC, European Society of Cardiology; CCS, Canadian Cardiovascular Society

^a.From updated guideline published in 2016 regarding bicuspid aortic valve patients (see reference 81).

^b.Turner Syndrome, Loeys-Dietz Syndrome, Ehlers-Danlos Syndrome

^c.In the setting of familial aortopathies, a higher threshold of 4.5–5.0 cm was recommended in the 2014 CCS Guidelines.

In addition to absolute diameter of the aneurysmal segment, the rate of growth can be utilized to guide management decisions as increased aneurysm rate of growth carries increased rate of complications.⁸⁷ Both 2010 AHA and 2014 CCS guidelines recommend consideration of intervention for an aneurysm growing faster than 0.5 cm/year (Table 2; Class I Recommendation, Level of Evidence C).^72,79 ESC guidelines are slightly more conservative with an annual growth rate of 0.3 cm/year quoted.⁷³ While these guidelines all apply to asymptomatic patients, the presence of symptoms from the aneurysm or concomitant cardiac surgery generally lower the threshold for operative intervention, but a detailed discussion of all exceptions is beyond the scope of this review.

In the case of diagnosis not meeting criteria for immediate intervention, it is reasonable to medically manage the patient (i.e., smoking cessation, anti-hypertensives, statins) with appropriate surveillance imaging. The 2010 AHA guidelines recommend annual imaging for aneurysms measuring 3.5–4.4 cm and semi-annual imaging for aneurysms measuring 4.5–5.4 cm⁷² with 2014 CCS guidelines expressing similar intervals.⁷⁹ In general, surveillance imaging should utilize the same modality across time to minimize discrepancies (Class I Recommendation, Level of Evidence C) and should involve the lowest iatrogenic risk (Class I Recommendation, Level of Evidence C).⁷³ Guidelines suggest use of MR imaging over CT in serial imaging as this avoids radiation exposure (Class IIa Recommendation, Level of Evidence C; Conditional Recommendation, Low-Quality Evidence), although TTE can be considered an alternative to MR in isolated root aneurysms (Conditional Recommendation; Low-Quality Evidence)^72,73,79 and has more recently been advocated as the optimal surveillance imaging study.⁷⁵

Surgical Versus Percutaneous Closure

Since its first description in 1956,⁸⁸ open surgical repair of SVA has been the definitive treatment option. Although the rarity of this condition has precluded clinical trials to determine optimal approach, modern surgical technique utilizes cardiopulmonary bypass (CPB), including standard dual venous cannulation and aortic cannulation with cross-clamping (assuming the integrity of the aorta outside of the root is preserved) via median sternotomy.^31,35,70,89 Some reports have described “on-pump, beating-heart” repair of SVA in combination with antegrade and/or retrograde cardiac perfusion with similar quoted early mortality,⁹⁰ although long-term follow-up is lacking. Once CPB is established and cardioplegia is instilled, an aortotomy is made and the aortic root is inspected. In the case of unruptured aneurysm or aneurysm with rupture into either ventricle without concomitant VSD, most reports detail repair through only an aortotomy.⁸⁹ With rupture of the aneurysm, a “dual chamber” approach is generally preferred in which an aortotomy is made together with an incision in the chamber into which the aneurysm ruptures.^35,70,71,91 The aneurysmal sac is then resected and the sinus of Valsalva is repaired either primarily or with a patch. Primary repair is typically reserved for smaller aneurysms as primary repair of larger aneurysms can cause distortion of the aortic root; patch repair is undertaken for larger aneurysms. In addition to repair of the aneurysmal segment, other concomitant cardiac structural abnormalities (i.e., aortic insufficiency, VSD, etc) are treated at the time of operation. In general, this repair carries low mortality (1–7%) and excellent long-term survival, even in the setting of rupture, and recurrence of the SVA is relatively rare.^{28,31,33,70,89} Major complications associated with the procedure, aside from those associated with CPB and cardioplegic arrest, include aortic valve insufficiency, persistent VSD, and atrioventricular (AV) conduction abnormalities.^28,70,71 It is imperative to check the integrity of the aortic valve before separation from CPB as residual insufficiency can progress to congestive heart failure in these patients. Generally, aortic valve replacement or repair is undertaken in this situation,⁹² but there is little evidence comparing outcomes of intervention versus non-intervention. In contrast, most cases of AV conduction abnormalities resolve, although reports of permanent pacemaker insertion being required have been published.^28,71

The potential complications from an open surgical approach combined with advancements in techniques and devices have made percutaneous closure of SVA an attractive option. Initially described about 25 years ago in a patient who had previous open repair of a SVA,⁹³ a Rashkind umbrella (a single-sided device with hooks to occlude flow across the communication) was placed via a transarterial approach with successful occlusion of a ruptured SVA. Modern approaches are generally transvenous (as this generally avoids the tortuous course around the aortic arch) and use a variety of devices, with the most common being Amplatzer ductal occluders followed by other patent ductus arteriosus (PDA) occluders, VSD occluders, and Amplatzer septal occluders.⁹⁴ In the transvenous approach, a retrograde exchange wire is placed through the aorta and snared from the venous assembly to allow access to both sides of the ruptured aneurysm. With access to the arterial and venous side of the rupture, an occluder can be floated. Specific contraindications to the percutaneous approach include moderate to severe aortic insufficiency, large (>10–12 mm) defect size, multiple sites of rupture, presence of large concomitant VSD, active endocarditis, and other defects that require open repair. In addition, although not a specific contraindication, recent studies have demonstrated that ruptured aneurysms with larger Q_P:Q_S (pulmonary flow:systemic flow) ratios are best suited for open surgical repair.⁹⁵ The procedure is generally well-tolerated in this selected patient population with success rates generally quoted at 90–100% and mortality rates ranging from 0–7% in these small case series.^94–97 Significant complications, some requiring urgent surgical intervention, have been reported, including pericardial tamponade, acute onset or worsened aortic insufficiency, device embolization, and residual shunt.

While the rarity of this pathology makes randomized trials difficult, retrospective analysis has demonstrated that percutaneous closure of SVA is an acceptable alternative to open repair, especially in those patients who might not be able to tolerate cardiopulmonary bypass.^94,95 Still, it is recognized that percutaneous closure is reserved for relatively small defects without concomitant structural defects and that more complicated repairs should generally be performed via an open surgical approach. Moreover, an alternative approach via right thoracotomy has been described in the literature.⁹⁸ These have resulted in successful repair of the SVA, but follow-up and postoperative assessment is lacking.

Pre-Anesthesia Assessment

Patients with SVAs can present for surgery either in the setting of acute rupture or for repair of an unruptured aneurysm that has met size criteria. Rupture generally precipitates symptoms as previously described, and the urgency in repair is driven by the propensity for the lesions to worsen over time and require more extensive correction.⁹⁹ Thus, the work-up of these patients may need to be expedited once the initial diagnosis is made. In patients presenting with asymptomatic unruptured aneurysms, the management will be largely driven by the size of the aneurysm and the patient’s medical comorbidities. Patient history should be obtained regarding symptomatology as this may provide additional insight into compromised cardiac structure and function. Physical exam findings and initial diagnostics, as discussed above, should be reviewed for any other sequelae of the aneurysm as well as the patient’s other medical comorbidities.

Intraoperative Considerations

Given the possibility of cardiac tamponade, coronary ischemia, malignant arrhythmias, and acute heart failure, an arterial line should be placed prior to induction of anesthesia. In preparation for surgical repair with cardiopulmonary bypass, the patient should have large-bore intravenous access in case the need for large volume resuscitation arises. Central venous access should be obtained for infusions of vasoactive and inotropic medications. Pulmonary artery (PA) catheterization may be helpful to guide management of patients with right heart failure. Although not an absolute contraindication to placement,¹⁰⁰ careful consideration should be given in patients with rupture into right-sided structures as placement may be challenging because of altered anatomy¹⁰¹ and there is the possibility of causing further damage. Induction of anesthesia can be complicated in the presence of cardiac tamponade, decompensated heart failure, or tenuous coronary anatomy. A cardiac surgeon should be present at induction in unstable cases in which decompensation necessitating emergent CPB is possible.¹⁰²

Patients deemed appropriate for percutaneous closure can avoid sternotomy and cardiopulmonary bypass. The case is often performed under monitored anesthesia care. An arterial line is still necessary for hemodynamic monitoring, but central venous access is likely possible via the venous sheath placed by the proceduralist. Therefore, good large-bore peripheral access can serve as a volume line, and the venous sheath for infusions. Conscious sedation, however, will negate the use of TEE for monitoring during the procedure, and so TTE and fluoroscopy are used instead.

In surgical cases, TEE serves as an invaluable tool for confirmation of pre-operative imaging findings and for assessment of impact on cardiac structure and function (Table 3).¹⁰³ The echocardiographer should look for mass effect on the RVOT, regional wall motion abnormalities from coronary ischemia, valvular dysfunction, and identification of fistula size and location. Moreover, TEE can be used to diagnose other concomitant structural abnormalities such as ventricular septal defects that would need addressing during the SVA repair.

Table 3.

Suggestions for Pre and Post-Bypass Focused Transesophageal Echocardiography

Pre-Bypass Exam

Post-Bypass Exam

Assess aneurysm location and size Assess for potential fistulous connections and quantify left to right shunt if present Evaluate for diastolic flow reversal in the descending thoracic aorta Evaluate for aortic insufficiency Evaluate coronary ostia location and flow, and wall motion if involved Assess right ventricular function if left to right shunt is present Examine for associated congenital defects, most commonly ventricular septal defect, bicuspid aortic valve, and atrial septal defect

Evaluate repair integrity Evaluate for post-repair aortic insufficiency Assess integrity of adjacent valves Examine for change in previously appreciated findings

The best views for evaluating the sinuses of Valsalva are likely the mid-esophageal (ME) aortic valve short-axis (with a slight withdrawing of the probe) and the ME aortic valve long-axis. While the ME aortic valve long-axis is often used to measure the width of the aortic root using leading edge-to-leading edge measurements in diastole, it is important to also examine the root in short-axis because with SVAs the dilation will likely be asymmetrical. Continuous wave Doppler can be used across the fistula to determine the pressure gradient between the left and right systems and the amount of blood flow. A Q_P:Q_S performed by comparing the velocity-time integrals at the pulmonic and aortic valves can also estimate the amount of left-to-right flow.

As discussed previously, the majority of aneurysms rupture into the right ventricle, followed by the right atrium and rarely the left atrium and ventricle. The aneurysms that rupture into the right-sided cardiac chambers present with left-to-right shunt complicated by RV overload and strain and, ultimately, failure. Measures should be undertaken to offload the right ventricle and promote forward flow in both the pulmonary and systemic vasculature.¹⁰⁴ Mechanical ventilation will likely worsen RV function as positive pressure ventilation causes a decrease in RV preload and an increase in RV afterload.¹⁰⁵ RV afterload reduction can be accomplished by minimizing hypoxic pulmonary vasoconstriction (i.e., avoiding hypoxia, hypercarbia, and hypothermia) as well as utilizing inhaled pulmonary vasodilators, ensuring inotropic support, and maintaining adequate perfusion pressure.

In some instances, dilation of the aortic root will cause widening of the aortic valve annulus and functional regurgitation; the aortic cusps themselves being altered or damaged has also been reported. Whether or not to perform an aortic valve replacement at the time of SVA patch repair is a subject of debate in the surgical literature.^106–108 Intraoperative TEE can be instrumental in providing information about the valve mechanics and dynamics before and after aneurysm repair. Other valves that may be involved are the tricuspid valve, but intervention on the right side of the heart is usually not needed once the shunt has been closed.⁶⁴

In rare instances, blood flow through the coronary ostia may be inhibited by anatomical distortion caused by mass effect. Such patients present with symptoms of acute coronary syndrome such as chest pain or EKG changes.^109,110 Optimizing coronary blood flow and reducing myocardial oxygen demand is particularly important in these patients – maintaining a low heart rate to allow for diastolic filling time and keeping diastolic blood pressure adequate for coronary perfusion is essential. The affected coronary artery usually requires reimplantation after the SVA has been excised and patched.