Classification of Vascular Rings and Related Malformations

Aufbau Des Vierzylinder Reihmotor

After different attempts of classification (Krauss, Rathke, Neuhauser, etc.), Stewart et al. 5 provided a pertinent system explaining malformations. Most vascular rings and related malformations of the aortic arch result from either a lack of regression or an abnormal regression of segments. The formation of the normal aortic arch system is dependent primarily Fig. 2.1. Schematic diagram indicating the various components of the embryonic aortic arch complex in the human embryo. Those components...

Natural History

TAR has been long considered a surgical emergency. This concept is primarily based on the historical study by Parmley et al. 2 in 1958, who reported autopsy findings in 296 nonpenetrating TARs among Korean War victims. Remarkably, the analysis of Parmley et al. estimated that 85 of the victims died on the scene from free aortic rupture of those who survived at least for 1 h, 30 died within 6 h, 49 within 24 h, and 90 within 4 months. The impressive negative natural history of TAR victims gave...

Introduction

Intramural aortic hematoma (IAH) and penetrating aortic ulcers (PAU) are part of the so-called acute aortic syndrome (AAS). This new cardiovascular syndrome embraces a heterogeneous group of patients with a similar clinical profile that includes classic aortic dissection, IAH and PAU (Fig. 27.1) 1 . The physiopathologi-cal mechanism that precipitates the appearance of each of these entities is different and the natural history of the last two aortic lesions is not well known. Currently, we know...

Current Therapeutic Strategy

The prevalence and the gravity of the lesions associated with the aortic rupture (Table 32.1) in our series are in accordance with data recently published. It is to be noted that no patient died from hemorrhage. Six deaths out of ten (60 ) were directly related to an associated lesion, five being possibly worsened by full hepariniza-tion during CPB two cases of intracerebral hematoma following a major head injury and three cases of respi Table 32.4. Comparison of mortality and paraplegia rates...

Medical Therapy

Medical therapy has been developed based on the assumption that aortic dilation and dissection are favoured by the repeated aortic stretch secondary to blood ejection by the left ventricle. Therefore, it was initially aimed at decreasing dp dt and the rebound wave. The use of beta-blockers in this setting was rein forced by the observed benefit on turkeys prone to aortic dissection 26 . However, invasive haemodynamic measurements performed in patients scheduled for aortic surgery (and hence...

Trauma

Despite advances in surgical and reanimation techniques, surgery is still associated with significant morbidity and mortality rates ranging between 8 and 15 depending on whether circulatory assistance to maintain satisfactory perfusion of the distal aorta is used or not 25 . The postoperative paraplegia rate without circulatory assistance can be as high as 19 and increases significantly when the aorta is clamped for more than 30 min 26 . With circulatory assistance, the rate is about 2 25...

Clinical Presentation

Despite the severe nature of the injury the clinical signs are ambiguously meager. In the diagnosis of acute TAR, it is imperative to maintain a high index of suspicion of the likelihood of this lesion in victims of high-speed-deceleration injuries, whether or not there is external evidence of thoracic injury. The signs of aortic rupture are not specific and when head, facial, orthopedic, and visceral lesions coexist, their own clinical features attract the attention of the physician. Chest...

Type of Replacement

The type of replacement has been the subject of continuing controversy. After the introduction of the deep hypothermic circulatory arrest, orthotopic tubular replacement of the aortic arch became the standard, at Fig. 10.6. Schematic drawing of ascending and partial arch replacement. The exact level of the distal anastomosis has little or no impact on morbidity or mortality Fig. 10.6. Schematic drawing of ascending and partial arch replacement. The exact level of the distal anastomosis has...

Experiments on the Hemodynamics of True Lumen Collapse

An in vitro study at Stanford created two aortic dissection phantoms to investigate the causative factors for true-lumen collapse and to develop effective treatments 13, 14 . One phantom was compliant and opaque (Fig. 3.1), and the other was rigid and transparent (Fig. 3.2). The rigid, transparent phantom was created to allow visual observation of the true lumen along the length of the aorta. Each phantom had the following physical features to model a Stanford type B aortic dissection an aortic...

Stenting and Fenestration

For a few years, new therapies have been available percutaneous stenting and fenestration 7 . They represent an alternative to surgical treatment especially in some high-risk patients, in the case of an involved descending aorta aneurysms, dissection and traumatic rupture of the isthmus, asacute as in chronicle phases. Fenestration is particularly useful in aortic dissection. During the procedure, TEE can easily identify true and false lumen. An immediate evaluation of treatment can be assessed...

References

Fabian TC, Richardson JD, Croce MA, Smith JS, Rodman G Jr, Kearney PA. Prospective study of blunt aortic injury multicenter trial of the American Association for the surgery of trauma. J Trauma 1996 42 374-383. 2. Von Oppell VD, Dunne TT, De Groot MK, Zilla P. Traumatic aortic rupture twenty year metanalysis of mortality and risk of paraplegia. Ann Thorac Surg 1994 58 585593. 3. Kipfer B, Leupi F, Schuepach P, Friedli D, Althaus U. Acute traumatic rupture of the thoracic aorta immediate or...

Results

Hospital mortality mainly depends on the urgency of the operation, age, and the presence and degree of atherosclerosis. Elective arch replacement is possible with a mortality rate of 2-6 . In patients over the age of 80 years, mortality may be as high as 8-15 . In Fig. 10.9. Computed tomography of the chest after total arch replacement with an elephant trunk. The graft extension can be seen easily there is the of beginning thrombosis of the aortic lumen around the trunk We commonly perform...

Diagnostic Investigations

A computed tomography (CT) scan of the chest will be available for almost all patients at the time of referral. It gives almost all the information necessary regarding the aorta itself, i.e., diameters, extension of the aneurys-matic process, and anatomical relationship with neighboring structures including the chest wall. If not already available, a CT or an MRI scan should be available before every operation performed on an elective basis. It is of vital importance when planning any aortic...

Operative Techniques

The purpose of endografting for the treatment of aortic dissection is to close the entry tear located in the descending thoracic aorta, which usually does not have large branches contributing to type II endoleak. Therefore, the device could be simple compared with that used for the treatment of abdominal aortic aneurysms. Although some devices are already commercially available in western countries, so-called first-generation endografts, Fig. 20.4. An axial computed tomography (CT) image shows...

Microbiology

Before the era of antibiotics, the most common germs were Streptococcus and syphilis 19 . Since the introduction of antibiotics and their significant use, the nature of responsive germs has changed. Currently, the commonest bacteria in the thoracic aortitis are the grampositive cocci which occur in 60 of cases (Table 25.1). Among them, Staphylococcus aureus represents, according to studies, between 30 and 50 of all aortitis cases. Streptococcus is the second commonest bacterium found. It is...

Conclusions

Replacement of the aortic arch for degenerative aneu-rysms is a standardized procedure which can be performed with a low risk. Both operative technique and cerebral discussion are still the subject of controversial discussion. In many patients standard arch replacement using hypothermic arrest yields excellent results. Technical modifications should be kept in mind to be able to apply an individualized approach to patient and aortic pathology in difficult situations. 1. Cooley DA, Mahaffey DE,...

Indications for Surgery

The indications for surgery are based on the appreciation of the risk of aortic dissection. Factors associated with increased risk are First of all, the aortic diameter at the level of the sinuses of Valsalva (maximal diameter) 35 (cf. supra). The risk increases dramatically after 60 mm, although aortic dissection may occur when the aorta is of normal size 37 . Indications for surgery have been proposed in the past when the aortic diameter was 60 mm. With the progress in surgery, the limit of...

Dissection

Despite the frequency of acute aortic dissection, there are few large series published on the outcomes of dissections and most are long retrospective multicenter studies confounded by inconsistent methods of treat ment and data collection. The IRAD study, a prospective multicenter registry has now been created to address some of these concerns. This study 7, 8 provides better understanding of the clinical profile and outcomes of patients with acute type B aortic dissection, helping clinicians...

Balloon Angioplasty for Native Coarctation

Following the first documented treatment of balloon an-gioplasty for recurrent coarctation 13 , this technique was applied to native coarctation in a critically ill neo-nate 25 and led to several clinical studies 26-28 . The greatest limitation of balloon angioplasty for the treatment of native coarctation is the occurrence of aortic aneurysms 28 . Patients treated for coarctation by surgical correction or stent implantation are also susceptible to aneurysms 9, 29 , but there is an increased...

Risk Factors

The risk factors are mainly marked by those of atherosclerosis male sex, age, tobacco smokers, hypertension, diabetes mellitus, dyslipidemia 9, 11, 12 . Congenital anomalies of the aorta (coarctation of the aorta, ductus arteriosus) also represent risky situations 14 . The immune statute of the patient also seems to play a role with probably an increased risk in the event of immune system depression mainly caused by diabetes mellitus, treatments (corticosteroids, immunosuppressive treatments)...

Results of Endografting

Nienaber et al. 29 should be credited as being first to objectively prove the efficacy of endografting for the treatment of chronic aortic dissection. They treated 24 patients with chronic aortic dissection 12 patients with endografting and 12 patients with surgical graft replacement. Endografting was associated with no mortality or morbidity, whereas conventional surgery was associated with four deaths and five serious adverse events in their series. Although the number of the patients and the...

Surgical Treatment of Chronic Descending Aortic Dissection

18.1 Introduction 181 18.2 Indications for Surgery 181 18.3 Surgical Techniques 182 18.3.1 Access 182 18.3.2 Thoracic Approach 182 18.3.3 Thoracoabdominal Approach 184 18.3.4 Abdominal Approach 184 18.4 Adjunctive Procedures 184 18.5 General Considerations Pitfalls During Surgery . 185 18.6 Additional Surgical Techniques 185 18.6.1 Descending Thoracic Postdissection 18.6.2 Thoracoabdominal Aneurysms 186 18.7.1 Stroke 186 18.7.3 Renal Failure 186 18.7.4 Visceral Ischemia 187 18.7.5 Pulmonary...

Pathology

As in ascending aortic aneurysms, atherosclerosis and connective tissue disorders are the two most frequent underlying diseases 5, 6 . Luetic aneurysms have become a rarity. Morphologically, degenerative aneurysms of the aortic arch are mainly seen in two distinct forms. The majority of aneurysms are fusiform and thus so-called true aneurysms. They are rarely found isolated in the arch, but most often represent the arch extension of proximal, or - less frequently - distal aortic aneurysms (Fig....

Conventional Surgical Treatment

Surgical approach is made through a left postero-lateral thoracotomy in the fourth intercostal space, which allows access to the descending thoracic aorta as well as the heart and the trunk of the pulmonary artery. The goal of the surgical treatment is to clamp the aorta proximally and distally to the lesion, open the tear and repair it. This treatment leads to two types of discussion firstly, how to repair the lesion (direct repair or graft interposition) and, secondly, how to protect the...

Endovascular Treatment Strategies for Coarctation of the Aorta

Taylor, Jeffrey A. Feinstein 37.1 Introduction 363 37.2 Endovascular Treatments for Coarctation of the Aorta 363 37.2.1 Balloon Angioplasty for Recurrent Coarctation 363 37.2.2 Balloon Angioplasty for Native Coarctation 364 37.2.3 Stent Implantation 366 37.2.4 Immediate and Intermediate-Term Outcomes After Stenting 366 37.2.5 Complications Associated with Stent Implantation 367 37.2.6 Indications for Stent Implantation 368 37.3 Comparing Treatment Modalities 369...

Summary

Although further follow-up is mandatory, endografting for the treatment of chronic type B aortic dissection is seemingly a superior alternative to surgical graft replacement in terms of short and midterm results, even if first-generation endografts are used. To expand indication more sophisticated devices such as branched or fenestrated endografts should be necessary. Acute aortic dissection. Lancet 1998 2 827-828. Blum U, Voshage G, Lammer J, Beyersdorf F, Tollner D, Kretschmer G, Spillner G,...

Identification of the True and False Lumens

Identification of the true and false lumens is crucial in the endovascular treatment of aortic dissection. The true and false lumens behave differently. In most acute aortic dissection, the false lumen is prone to ectasia and is at risk of rupture, and the true lumen is prone to collapse and is at risk of compromise of its branch arteries. Numerous steps in the endovascular treatment of dissection require real-time knowledge of which lumen the guidewire, the diagnostic catheter, and treatment...

Transesophageal Echocardiography for Diagnosis and Treatment of Aortic Diseases

4.1 Introduction 4.2 Transesophageal Echocardiography for Diagnosis of Aortic Diseases 33 4.2.1 Aortic 4.2.1.1 Intimal 4.2.1.2 Intimal 4.2.1.3 True and False Lumens 36 4.2.1.4 Aortic 4.2.1.5 Aortic Branches 37 4.2.1.6 Periaortic 4.2.17 4.2.2 Intramural 4.2.3 Penetrating Aortic Ulcer 41 4.2.4 Aortic 4.2.4.1 Atherosclerotic Aneurysms 41 4.2.4.2 Dystrophic Aneurysms 41 4.2.4.3 Aneurysm of the Sinus of Valsalva 41 or Inflammatory Diseases 42 4.2.4.5 Aneurysms and Infectious Diseases 42 4.2.5...

Type A

Surgery remains the only treatment option for hemody-namically unstable patients with type A lesions. Medical treatment of type A IMH without an intimal tear, bed rest with antihypertensive treatment to minimize the risk of evolution towards frank dissection, can only be conceived in the case of important comorbidity and in the absence of menace of rupture. Supportive medical treatment with frequent follow-up imaging studies and timed surgical repair in cases with complications must remain the...

Of Abdominal Aortic Dissection

Renal, mesenteric, or spinal cord malperfusion approximately doubles the mortality of patients with acute aortic dissection 2 . Most of these malperfusion syndromes arise as complications of the dissection path through Fig. 23.3. A single lumen is prominent at the level of the aortic crura near the diaphragm in the same patient as in Fig. 23.2. Careful tracing of this lumen back to the heart shows that it is the false lumen, and that the true lumen is completely collapsed and nearly invisible....

Clinical Presentation and Diagnosis

Hypoplastic Aortic Arch Repair

The neonate with coarctation may have severe heart failure with acidosis, tachypnea and a profound diaphoresis with feeding. Depending on the patency of the ductus arteriosus and the severity of the coarctation, differential cyanosis may be present. Severe obstruction at the isthmus and ductus arteriosus requires intravenous infusion of prostaglandin Ex in the neonate. This relaxes the ductal tissue, lowering the resistance of flow through the aorta, improving ventricular function....

Emergence of Endografting

Endovascular repair including percutaneous fenestra-tion and stenting had been performed mainly for the treatment of visceral or leg ischemia before endograft-ing became clinically available. Its safety and efficacy have been reported by several investigators 30, 31, 37 . On the other hand, endografting was initiated for the treatment of abdominal aortic aneurysms and it is now a good alternative to surgical graft replacement for both abdominal and thoracic aortic aneurysms 2, 4 . Application...

Intraparietal Hemorrhage

IAH has also been documented at autopsy. Necropsy series have demonstrated that in some patients (5-13 ) with dissection the entrance tear is not evident 20-22 . On histologic analysis, a hematoma disrupting the aortic media is well documented (Fig. 27.5). In our experience, this hematoma is most often intramedial, but occasionally it is subadventitial (between the media and the adventitia). A subadventitial hematoma might have a greater risk of aortic rupture. This intramedial or...

Immediate and Intermediate Term Outcomes After Stenting

In 1991 O'Laughlin et al. 45 reported the first use of a Palmaz iliac artery stent to reduce the pressure gradient across a coarctation in the thoracic aorta (5025 mmHg) of a 12-year-old patient previously treated using balloon angioplasty. Subsequent case reports documented successful deployment of stents for palliative treatment of patients with severe coarctation that had been treated by surgery 46 , balloon angioplasty 47 or both 44 . Larger studies then emerged with six to 54 patients 9,...

Cerebrospinal Fluid Drainage

Drainage of CSF during aortic procedures was introduced to prevent the rise in CSF pressure (and consequent reduction in spinal perfusion pressure) that often occurs during aortic cross-clamping or in the early postoperative period. With this technique, a catheter is inserted into the lumbar spinal canal, and small amounts of spinal fluid (up to 50 ml prior to aortic clamping, 50 ml during aortic clamping and a maximum of 20 ml h in the postoperative period) are withdrawn on an intermittent...

Problems Encountered During and After Stent Graft Treatment of Aortic Dissection

21.1 Introduction 209 21.2 Materials and Methods 209 21.2.1 Patients 209 21.2.4 Procedures 210 21.3 Problems During the Procedure 211 21.3.1 Stent-Graft Migration 211 21.3.2 Complications Related to the Size of the Stent-Graft 211 21.3.3 Appearance of a Hidden Intimal Tear 21.3.4 Type I Endoleak 212 21.4 Problems During the Follow-Up 212 21.4.1 Postimplantation Syndrome 212 21.4.2 Neurologic Complication 214 21.4.3 Persistent Type I Endoleak 214 21.4.4 Type II Endoleak 215 21.4.5 Progressive...

Of Branch Artery Obstruction

The Michigan classification of branch artery obstruction 15 is based on the anatomical relationship of the dissection flap to the branch artery in question (Fig. 23.4). It is an intuitively appealing classification because this anatomic distinction forms the basis of distinct treatment strategies. The causes of obstruction may be distinguished as follows Mixed static and dynamic obstruction - Related to dissection thrombosis, embolism - Unrelated to dissection atherosclerosis, fibromus-cular...

Discussion

With the advances in stent-graft technique and technology EVAR is today applied in more complex anatomy. This is particularly true for the aortic arch, where a combination of open surgical repair techniques, including either extraanatomical bypasses or bypasses from the ascending aorta to the supraaortic vessels, or a total replacement of the aortic arch, may be necessary in order to find a less traumatic solution when applying EVAR in this area. It is an evolving field and it has been Fig....

Type B

Medical management is recommended for type B APU 16 . Stent-grafts permit a higher degree of protection against rupture than medical therapy alone. Because APU affect older persons, one must consider the patient's age, overall physical condition, and anticipated life expectancy in the decision to use operative treatment. If patients tolerate medical management without clinical deterioration, they may continue conservative follow-up care with reasonable safety 10 . This medical treatment is...

Regional Cooling

Direct cooling of the spinal cord has been applied in both the laboratory and the clinical setting, and has the theoretical advantage of deep cooling of the spinal cord whilst avoiding the drawbacks of profound systemic hy pothermia. Cooling of the spinal cord has been achieved in the experimental or clinical setting by direct perfusion of intercostal arteries with cold blood 61 , indirect perfusion by infusing cold blood into the clamped aneurysm 74 , retrograde perfusion through hemiazygous...

Vasodilators

Although dopamine dilates renal arterioles, increases renal blood flow, and has anti-aldosterone activity, its role as a renal protecting compound is questionable. Low-dose dopamine (0.5-3 p,g kg min) did not show any benefit in preventing renal failure in surgical patients, presumably because it has a mixed specificity for DA1 receptors, DA2 receptors and -adrenergic receptors 19 . Fenoldopam, a highly selective DA1 receptor agonist, has a similar vasodilating profile as dopamine. In patients...

The Frozen Elephant Trunk Technique

The complications that may be attributed to the elephant trunk itself and the cumulative risks of the staged approach are drivers for change towards new procedures and implants, which allow for risk reduction in the surgical treatment of large aortic aneurysms. Extensive one-stage repair techniques performed through a clamshell incision or through the left chest bear remarkable technical challenges and risks, too 17, 19, 28, 35 . They may therefore be limited to selected patients. A new wave of...

Traumatic Rupture of the Aortic Isthmus

Traumatic aortic injuries are becoming more frequent. They are related to the increase of blunt chest trauma owing to motor vehicle accidents. Falls from a elevated site represent the second cause. The mechanism consists in a sudden deceleration that submits the aortic wall to high shearing forces. The aortic isthmus, at the junction between the mobile arch and the fixed descending part, is especially exposed. Supraaortic arteries (8 ) and ascending and descending (3 ) aorta are less frequently...

Surgical Techniques

Surgical access is dependent on the extent of the aortic replacement. Figure 18.1 schematically depicts the different TAAs and TAAAs. Table 18.2 summarizes the surgical access for the corresponding aneurysms. Figure 18.2 depicts a giant post-type B dissection thoracic aneurysm. Figure 18.3 shows a perforation of the aortic wall and only thrombus in the false lumen prevented free rupture. Figure 18.4 illustrates the implanted polyester graft. It is obvious that the majority of type B, C and D...

Malperfusion

In the past creating a surgical reentry was the treatment of choice for malperfusion, but actually endovascular catheter-based interventions are the primary option 12 . Surgeons dealing with aortic problems should, however, keep themselves abreast of the technique of creating a surgical reentry because endovascular interventions might fail or be unsuccessful. Of course it can be performed at any aortic level it was most frequently used at the level of the upper abdominal aorta in order to...

Conclusion

From the available studies concerning patients undergoing surgery with DHCA one can conclude that two major issues have been involved in the improvement of outcome the application of selective ACP, and the recognition of cerebral ischemia during the rewarming phase. Apart from the hypothermia, additional pharmacological protection has not been shown to be effective in reducing adverse neurological outcome, although most clinicians administer barbiturates, steroids, and lido-caine before the...

Comment

In Sect. 11.3 we described our approach that allows for definite treatment of lesions of the aortic arch and beyond during a single-stage procedure by using a hybrid prosthesis, which combines the features of a stent graft and a conventional vascular prosthesis. The stented distal segment of the hybrid prosthesis is implanted into the descending aorta through the opened aortic arch under fluoroscopic control, while the proximal non-stented segment is used for conventional replacement of the...

To Identify New Biochemical and Genetic Markers

At the moment very few genetic and biochemical markers have been detected in TAAs, while many biochemical markers and few genetic markers have been found in AAAs these last markers are similar to those found in atherosclerosis. The fact that TAA has a different molecular background from that found in AAA or atherosclerosis is in part explainable by the fact that the aortic wall has a different structural protein composition that can contribute to the different pathologies. To address the...

Treatment Results

Most reports of endograft treatment of penetrating ulcers consist of single case reports or small-series patients embedded in large series of mixed thoracic aortic disease, from which it is difficult to elicit general principles of patient selection and anatomical features predictive of treatment failure. The Stanford group has published the results of endograft treatment of its first 26 patients with penetrating ulcers with or without intramural hemorrhage 3 . Treatment was between 1993...

Concept of Delaying Repair

During the early 1970s, Akins et al. 10 began to delay the repair of blunt aortic tears in selected patients with associated major injuries. Before the aortic repair, they were treated with antihypertensive drugs and no rupture of the traumatic false aneurysm was reported. Similarly, in 1995, Pate et al. 6 reported no rupture of pseudo-aneurysm of the thoracic aorta in 41 patients whose arterial pressure was maintained below 140 mmHg and who underwent delayed repair of the aortic tear between...

With Open Stent Graft Placement

This technique is recommended when concomitant heart surgery is performed, including coronary bypass, graft replacement with or without aortic valve remodeling in the ascending aorta due to aneurysm formation or type A dissection, or when there is a type A dissection continuing into the descending thoracic aorta 5, 6, 7 . In these situations a stent-graft may be placed from the distal aortic arch under hypothermic cardiopulmo-nary arrest and guided either fluoroscopically or by transesophageal...

True and False Lumens

The true lumen is generally smaller than the false one but presents a systolic expansion 7 . Color Doppler imaging presents an aspect of aliasing owing to the high velocity of systolic anterograde flow (Fig. 4.7). The false lumen is larger and presents a systolic compression. Blood velocity is lower and, sometimes, results in a constitution of the spontaneous echo contrast effect. It appears as dynamic smokelike echos with slow swirling movements that are markers of blood stasis. So, a thrombus...

Management of Segmental Arteries

One of the more controversial aspects of surgical technique for treating thoraco-abdominal aneurysms is the management of the intercostal arteries. Although several experimental studies have shown improved spinal cord protection with intercostal reimplantation, there has been difficulty transferring the results to the clinical setting as most animal studies do not mimic the clinical situation. In animal experiments, the interventions used are often limited to those being tested, whilst in...

Surgical Treatment of Acute Type B Dissection

17.1 Introduction 175 17.2 Indications for Surgery 175 17.3 Surgical Techniques 176 17.3.1 General Considerations 176 17.3.2 Use of Soft Clamps, Teflon Felt and Glue . 177 17.3.3 Access 177 17.3.4 Perfusion Techniques 177 17.3.5 Atriofemoral Bypass (Left Heart Bypass) . 178 17.3.6 Extracorporal Circulation (Partial or Total, Deep Hypothermic Circulatory Arrest) 178 17.4 Surgical Steps 178 17.7 Conclusion 180

Indications for Stent Implantation

In addition to adult or near-adult-sized patients in whom stent placement is now becoming the treatment of choice, stent implantation may be especially practical for diffuse lesions where longer angioplasty balloons would be more likely to induce aneurysms and surgical repair would require the resection of a large portion of the aorta 64 . Similarly, older patients with longer coarctation segments, but modestly compromised aortic elasticity, may opt for stent implantation as an alternative to...

Materials and Methods

Between July 1994 and December 2003, 60 patients with aortic dissections who underwent stent-graft placement in the DTA were included in this study. The protocol was approved by the Institutional Review Board, and informed consent was obtained from all patients. The 39 men and 21 women ranged in age from 37 to 88 years (mean 59 years). The inclusion criteria for the stent-graft were type A with retrograde dissection and an intimal tear located in the DTA, type B dissection with dynamic...

Surgical Treatment

With rare exception, vascular ring malformations are repaired through a left thoracotomy using the fourth interspace. The surgical dissection of the vascular ring should be complete enough to clearly identify the anatomy including the left subclavian artery and the liga-mentum arteriosum. The vagus and recurrent laryngeal Fig. 36.12. Anterior-posterior (left) and lateral (right) projections of an esophagogram demonstrating a double aortic arch type vascular ring malformation Fig. 36.12....

Profound Hypothermia and Circulatory Arrest

Greater degrees of hypothermia afford more protection to neural tissue, with the advantage that even longer periods of ischemia are tolerated, compared with nor-mothermic techniques. Because ventricular fibrillation or severe bradycardia is invariable with profound hypothermia, total body circulatory arrest is necessarily a component of this technique. Some groups, notably those of Kouchoukos et al. 71, 72 , advocate routine application of deep hypothermic circulatory arrest (DHCA) for...

Stent Graft

The advent of endovascular stent-graft technology provided a less invasive alternative to thoracic aortic injury treatment. This substitute to open thoracic aortic replacement is attractive for several reasons much of the surgical morbidity is reduced, sparing thoracotomy, aortic cross-clamping, and cardiopulmonary bypass. Moreover, spinal cord ischemic complications are infrequent probably because the duration of medullary hypotension is significantly reduced. Until now, the largest series of...

Biochemical Markers

Aortic dissection is an acute catastrophic aortic disease associated with high mortality and morbidity 4 . Rapid diagnosis and initiation of appropriate treatment is pivotal for patients with acute aortic dissection. Unfortunately, the disease is still not well recognized on clinical presentation owing to lack of specific signs and symptoms. Detection of acute aortic dissection is based on clinical presentation but mainly relies on imaging techniques 25 . However, up to 30-40 of patients remain...

Systematic Reimplantation of Segmental Vessels

Using this approach, the segmental arteries from T7 or T8 to as low as L2 (depending on the extent of resection) are reimplanted. Systematic intercostal implantation is an integral component of the technique of several of the larger published series in the literature, such as those of Kouchoukos et al. 73 , Coselli et al. 44 , Jacobs et al. 89 , Kuniyoshi et al. 90 and Cambria et al. 91 . These groups all report paraplegia rates below 10 , which they attribute in part to their intercostal...

Elongation of the Landing Zone in the Aortic Arch

In patients with symptomatic type B dissections or aneurysms in the aortic arch, it is not uncommon to cover the left subclavian artery as a means of prolonging the landing zone and thereby achieving a secure hemostatic seal for a stent-graft. However, such a maneuver may not be sufficient. The stent-graft may need to be placed further cephalad and may cover the left carotid artery as well. In order to provide continuous flow to the blocked vessels an extraanatomic bypass from the innominate...

Intimal Defect with IMH

The intimal defect in this lesion again presents a target lesion for endovascular treatment. As noted earlier, it may be difficult in practice to classify a given defect as a penetrating ulcer or a bland entry tear. Two considerations affect the length of the aorta neighboring the intimal defect which is targeted for treatment. Evidence of atheromatous wall should favor more extensive treatment of the aorta with longer endografts, since radiographic imaging is relatively insensitive to shallow...

Adjunctive Procedures

Operations on the descending and thoracoabdominal aorta have been notorious for their detrimental effects on organs supplied from these portions. Paraplegia, renal failure and visceral infarction are most feared complications of extensive aortic repair. Because of the fragile aortic quality and limited collateral networks, these complications occur even more frequently in dissected aneurysms or aneurysmatic dissections compared with degenerative aneurysmatic disease. Spinal cord protection can...

And Selective Visceral Perfusion

Estrera, Tam T. T. Huynh, Eyal E. Porat, Hazim J. Safi 13.1 Introduction 141 13.2 Operative Technique and Adjuncts 142 13.2.1 Cerebrospinal Fluid Drainage 142 13.2.2 Thoracoabdominal Incision 143 13.2.3 Diaphragm Preservation 143 13.2.4 Distal Aortic Perfusion 143 13.2.5 Sequential Cross-Clamping 144 13.2.6 Reattachment of Intercostal Arteries . . . 144 13.2.7 Visceral and Renal Perfusion 146 13.3 Impact of Adjuncts on Outcome 147 13.3.1 Neurological Deficit...

Selective Reimplantation of Segmental Vessels

Selective reimplantation has been advocated because of the drawbacks of systematic reimplantation longer aortic clamp times, which potentially increase the paraplegia risk, use of large aortic wall patches, which may predispose to future aneurysmal dilatation of the included aortic wall, and extra anastomoses, which increase the potential for bleeding. Because anatomical understanding of the spinal circulation suggests that not all patients will achieve useful anterior spinal cord...

Mild to Moderate Systemic Hypothermia

Abundant animal and clinical studies have shown that deep hypothermia protects neural tissues from ischemic injury during periods of circulatory arrest 34 . The basis for the protective effect of hypothermia is a combination of various mechanisms including reduced metabolic rate, inhibition of release of excitatory neurotransmitters (particularly glutamate) and reduced production of superoxide anions 64 . Although most of the experimental work on neuronal protection has concerned deep...

Imaging of Aortic Ulcers

Atherosclerotic ulcers represent an unremarkable evolution of atheromatous lesions, frequently seen in the abdominal aorta and iliac arteries, which are usually stable over time and rarely prone to complications. Most aortic ulcers are incidentally discovered and are confined to the inner part of the aortic wall. However, in the thoracic aorta some of them may penetrate deeply into the wall and cause a localized or dissecting IMH (Fig. 28.3), a dissection or an aortic rupture. This specific...

Dissection Mechanism

The two mechanisms regarding the initial event in aortic dissection are primary intimal tear and initial dela-mination of the tunica media produced by the formation of an intramural haemorrhage. There are different lesions which can generate a primary entry tear of dissection, such as atherosclerotic lesions of the aortic intima, penetrating aortic ulcers, or iatrogenic intimal lesions 7, 21 . The second mechanism arises from bleeding of the vasa vasorum of the media (Fig. 16.1). All mechanisms...

Aneurysms and Infectious Diseases

Syphilis involves generally the upper part of the ascending aorta. Lesions consist in pseudoaneurysm with a thrombus and calcification of the aortic wall. Actually, small mycotic aneurysms may be observed during bacterial or parasitical infections. In such situations, after aortic surgery, images of a false aneurysm may be observed at the anastomosis between the aortic tube graft and the native aorta. Fig. 4.16. Marfan syndrome multiplane transesophageal views, a Enlargement of aortic annulus...

Steal

Steal is one concept that unifies most of the various strategies that have been successful at reducing paraplegia rates. Steal is a pathological process whereby increased blood flow through a low-resistance vascular bed is sufficient to direct flow away from a critical region in this setting, the spinal cord 119 . The various connections of the spinal cord arterial supply mean that blood can be diverted toward and away from the spinal cord, and toward and away from other competing vascular beds...

Potential Limitations

The potential limitations to endovascular treatment are the site of the rupture in regard to other anatomic land marks, the difficulty of vascular access, and the availability of the device in an emergency situation. The success of the endovascular procedure greatly depends on rigorous respect of anatomic criteria, mainly the length of the proximal neck, which must be 10 mm or more beneath the origin of the left subclavian artery. If needed, covering the left subclavian artery to lengthen the...

Problems During the Procedure

Migration of the stent-graft caused by the wind sock effect of ventricular ejection results predominantly in technical failure, particularly when proximal fixation is at or near the aortic arch 2 . To avoid this serious technical problem, lowering the blood pressure with a vasodilator or beta-blocker drugs has been done 16, 25 . Despite this effort, stent-graft migration has reported to occur with an incidence of 2-20 by many authors 29 . In our experience, we observed two cases (3 ) of...

Conclusion Therapeutic Guidelines

To conclude, visceral malperfusions must be systematically investigated (preferably by thoracic, abdominal and pelvic CT angiography) during the course of aortic dissections as their presence leads to high mortality. Yet visceral malperfusions can be treated using effective en-dovascular therapies. Their presence leads to a change in the treatment guidelines and lends too much credence to the overly classic dogma a type A dissection must be surgically corrected and a type B dissection must be...

General Considerations Pitfalls During Surgery

Surgery for postdissection aneurysms differs from surgery for degenerative aneurysms. In general, blood loss in postdissection aneurysms is more profound because the majority of side branches are patent. As an example, in postdissection thoracic aneurysms, the majority of intercostal arteries are open, whereas in degenerative aneurysms the majority are occluded by plaques or thrombus 8 . A certain number of 3-French occlusion balloons should be on the sterile table to block the back-bleeding...

Anatomy

The critical role of the descending aorta in the arterial blood supply of the spinal cord makes the spinal cord vulnerable to ischemia during disease processes or in terventions that involve the thoraco-abdominal aorta. The arterial supply to the spinal cord has been well studied 3 . The spinal cord is supplied via three longitudinal arteries the anterior spinal artery, and the two posterior spinal arteries. The anterior artery is larger than the two posterior arteries, and provides 75 of...

Sacrificing of Segmental Vessels

Systematic sacrifice of intercostal vessels has been employed by Griepp et al. 8, 21 and Galla et al. 101 . Intercostal reimplantation is not an integral part of their technique, and is only undertaken if evoked potentials suggest spinal ischemia when intercostal arteries are occluded. With this approach, the lower vessels are temporarily occluded in a stepwise and gradual manner prior to aortic clamping. Vessels are occluded in triplets every 10 min, after which motor and sensory potentials...

Aneurysm of the Sinus of Valsalva

Aneurysm of the sinus of Valsalva is an infrequent disease, mainly observed in young men. A congenital origin is frequent and explains associations with other abnormalities bicuspid aortic valve with regurgitation, coarctation, interventricular septal defect. Other etiologies are Marfan syndrome, endocarditis or inflammatory diseases of the aortic wall 11 . There are two TEE aspects localized dilatation (generally right anterior part) of the sinus or fingerlike expansion of the sinus (Fig....

Aortic Branches

Mechanisms of the involvement of aortic branches are multiple dissection, disinsertion or obstruction of the artery ostium, compression by the false lumen. Except Doppler flow within the true lumen (TL), c M mode at the same level, d M mode color Doppler image into the true lumen Doppler flow within the true lumen (TL), c M mode at the same level, d M mode color Doppler image into the true lumen for the left subclavian artery, TEE fails to analyze these complications (Fig. 4.8). However,...

Selective Spinal Cord Perfusion

Some workers further attempt to reduce spinal cord ischemia by continuously perfusing the lower intercostal arteries. Experimentally, it has been demonstrated in pigs that segmental artery perfusion can protect the spinal cord for up to 60 min of ischemia 60 . But in this study, the control group had simple aortic cross-clamping without distal perfusion, which is not reflective of the clinical scenario, where adjuncts are frequently used. Selective spinal cord perfusion has been applied...

Pathogenesis

Aortic wall integrity depends mainly on two factors contention resistance of its internal and external layers, determined by their biochemical and anatomical structure, and aortic parietal stress, which is in relation to arterial tension, luminal diameter and parietal thickness. All this can be expressed by a modified equation similar to the law of Laplace, where circumferential stress is directly related to blood pressure and aortic diameter, and inversely to parietal thickness. As mentioned...

Imaging of Intramural Hematomas

IMH is classically defined as an aortic wall hematoma without entry tear and intimal flap 32, 33 . With different imaging techniques, it appears as a regular cres-centic or circumferential aortic wall thickening, larger than 7 mm, with central displacement of intimal calcifications, typically hypoechoic on TTE-TEE 33 , with a high attenuation value on unenhanced CT during the first week and with a high Tl-weighted signal on MRI after the first week. However, there is no consensus on diagnostic...

Methods

Preoperatively, an epidural catheter and a CSF drain are placed prior to operative intervention. Full intraoperative monitoring is employed, including radial and femoral artery pressure monitoring, large-bore intravenous access, and transesophageal echo (TEE). A double-lumen endotracheal tube facilitates operative exposure and minimizes operative trauma to the left lung. Both femoral arterial and venous access are attained via an oblique supra-inguinal crease incision. Long, flexible,...

Requirements

The procedure could be conducted in an angiosuite or an operating room. If it takes place in a radiology department, the angiosuite has to be set up like an operating room in order to ensure its safe management. The ventilation must be standardised so that the air is renewed in conformity with the rules of hygiene and evacuation of anaesthetic gas. The anaesthetic fluids must be available oxygen, medical air, nitrous oxide and medical vacuum. Of course, the material necessary for haemodynamic...

Integrity of Anatomical Pathways

Spinal cord blood flow depends upon anatomical integrity of the circulation described earlier. Anatomical in terruptions to the intrinsic or extrinsic blood pathways predispose to regional insufficiency in blood flow. Acute occlusion of intercostal or vertebral inflow (owing to trauma, dissection, endovascular stenting or surgery), in patients with such preexisting interruptions, can result in spinal cord infarction. In more chronic occlusions (which frequently occur in atherosclerotic...

Clampand Sew Techniques

Exclusion of the diseased aorta with clamps, and expeditious anastomosis with limited cross-clamp time, was the original method for repair of aneurysms. This technique was used exclusively by many surgeons for even the most extensive thoraco-abdominal aneurysms during the 1960s and 1970s. No adjuncts are employed. Modifications of this technique include that of Cooley, in which only a single proximal clamp is placed, and the distal body is exsanguinated whilst performing both proximal and...

Operative Technique and Adjuncts

The patient is brought to the operating room and placed in the supine position on the operating table and prepared for surgery. The right radial artery is cannu-lated for continuous arterial pressure monitoring. General anesthesia is induced. Endotracheal intubation of the patient is established using a double lumen tube for selective right lung ventilation during surgery. A sheath is inserted in the internal jugular vein, and a Swan-Ganz catheter is floated into the pulmonary artery for...

Dystrophic Aneurysms

Dystrophic aneurysms involve principally ascending aorta up to the innominate artery. The typical aspect is that of annulo-aortic ectasian disease. Etiologies include the Marfan syndrome (principally in patients younger than 40 years), characterized by mutation of genes localized on chromosome 15, and idiopathic forms. These forms present nearly similar histologic lesion of kystic medianecrosis. Dilatation involves the valve annulus, the sinus of Valsalva and sometimes the sinotubular junction....

Info

Tremities of the flap, or else the dissection is continued around the remainder of the circumference, extending the height of the fenestrated aorta. This latter mechanism is the most frequent. It can then be useful to unfold the flap by inflating a large-diameter balloon (over 12 mm) inside the thoracic aorta and retracting it as far as the iliac junction, with the balloon inflated. The risk of a torn flap folding back on itself must be taken into account as this can turn and trigger ischemia...

Additional Surgical Techniques

In addition to the techniques described in the previous sections and protective measures, some other important recommendations and variants have to be mentioned. 18.6.1 Descending Thoracic Postdissection Aortic Aneurysms Following access and starting left heart bypass, it is technically easier to perform the distal anastomosis first. The cross-clamp has to be at least 5 cm distal to the planned area of anastomosis, because resection of the dissected membrane has to be performed, allowing distal...

Pitfalls

TEE evaluation of aortic dissection includes some pitfalls that can impair its accuracy intimal flap artefacts, localized or retrograde dissections, aneurysm or false aneurysm with a thrombus, complex plaque of athero- Ech3 tGOdB C 3 Persist Bas Oplira 2D Gsn Cad lmag Moy Ech3 tGOdB C 3 Persist Bas Oplira 2D Gsn Cad lmag Moy Fig. 4.10. Aortic dissection. Linear artefacts into ascending aorta. a Two-dimensional long-axis view. b M mode. c Color Doppler image showing homogeneous flow Fig. 4.8....

Monitoring

Although the effective time of arrest of cerebral perfusion has been substantially shortened by the application of antegrade low-flow cold blood cerebral perfusion, it is still important to assess cerebral temperature as accurately as possible. In our practice at Stanford this includes the measurement of bladder temperature, venous perfusate temperature, and two tympanic temperatures. Since hypothermia is applied for brain protection by diminishing cerebral oxygen consumption (CMR02), it is...

Blood Pressure

As is true of other organs, spinal blood flow demonstrates autoregulation, and maintains an adequate blood flow at arterial pressures between 50 and 135 mmHg in healthy adults. In animal models, when the blood pressure falls below 50 mmHg, spinal blood flow is increasingly compromised, with the incidence of spinal infarction rising steeply at blood pressures below 40 mmHg 13 . In patients with hypertension or severe atherosclerotic disease, autoregulation may be set at a higher level, such that...

Other Approaches

Other experimental approaches of monitoring cord spinal function include measurement of surface spinal oxygen tension, intrathecal oxygen levels, hydrogen ion electrode techniques and F-wave polysynaptic response complex monitoring 34 . The clinical role of these techniques is not established, and aside from application of the hydrogen electrode technique by Svensson 35 , their use is confined to laboratory studies. Examination of various biochemical markers in the blood and CSF has been...

Active Distal Bypass

Active bypass to the distal aorta overcomes the unpredictability of passive bypass. Blood is drained from the left atrium, and returned to the distal aorta, or to the femoral or iliac arteries. By adjusting the pump flow rate, the distal aortic pressure can be maintained between 60 and 70 mmHg, and by using a combination of partial exsanguination from the left atrium and retransfusion of blood, the proximal pressures are maintained at 70-80 mmHg 8 . Pharmacological agents are used minimally....

Postoperative Treatment

The immediate postoperation supervision consists primarily in supervising the awakening but also in following the arterial pressure and it maintenance below 130 mmHg, and a neurological monitoring in case of paraplegia. This supervision is best carried out in an intensive care unit for the first few hours. In the following days the patient should remain hospitalised with, in addition to neurological and vital signs monitoring, the monitoring of temperature and blood cell count The onset of an...

Operative Strategies

A thorough preoperative assessment, including physical examination, assessment of physiologic cardiac, pulmonary, and renal reserve, and scrutiny of available imaging modalities precedes operative intervention. Surgical as well as perfusion strategies are then decided. The major downside of femoral-femoral bypass is the necessity for full heparinization as a membrane oxygenator is an integral part of the perfusion circuit. Usually 300 IU kg is sufficient to maintain an activated clotting time...

Medical Management

Acute aortic dissection of the ascending aorta is highly lethal, with a mortality rate of 1-2 per hour early after symptom onset 6, 55 . Acute type A dissection is a surgical emergency. Medical management alone is associated with a mortality rate of nearly 20 by 24 h after presentation, 30 by 48 h, 40 by 1 week and 50 by 1 month. Even with surgical repair, the mortality rates are 10 by 24 h, 13 by 7 days and nearly 20 by 30 days, as recently documented in the largest registry of aortic...

Impact of Adjuncts on Outcome

Between 1991 and 2004, we performed repair of the descending thoracic and thoracoabdominal aorta in 1,106 patients 24 . Seven hundred five (64 ) patients were men. The patient distribution was 215 (19.5 ) for extent II and 891 (80.5 ) for all others. The median age of all patients was 68 years (range, 8-92 years). Three hundred fifty-five (32 ) patients were active smokers at the time of surgery. One hundred and eighteen (11 ) patients suffered from cerebrovascular disease. Forty-five (4 )...

Cerebrospinal Fluid Pressure

The effective spinal cord perfusion pressure is the difference between the mean arterial pressure and the cerebrospinal fluid (CSF) pressure. Because the spinal cord is in a closed rigid cavity, spinal cord perfusion pressure falls as the CSF pressure increases. It is not certain exactly what level of perfusion pressure is necessary to obtain effective cord perfusion, but extrapolation from clinical observations suggests that perfusion pressure should be greater than 40 mmHg for adequate spinal...