Aortic dissection presenting as acute lower extremity ischemia: report of a case

Although not common, acute leg ischemia is an important element in the clinical presentation of a patient with aortic dissection. This report describes a case of aortic dissection in which the main feature at presentation was acute right leg ischemia. The angiography showed right common iliac artery and external iliac artery occlusion. Diagnosis was made by clinical evaluation and angiography. Embolectomy was then attempted immediately but failed. Aortic dissection was highly suspected and confirmed by emergency computed tomography. Fortunately, the patient had good recovery. Aortic dissection is potentially lethal if misdiagnosed or if recognition is delayed. As such, aortic dissection should be considered in the differential diagnosis.     

Towards an understanding of the mechanics underlying aortic dissection

Acute aortic dissection and associated aortic catastrophes are among the most devastating forms of cardiovascular disease, with a remarkably high morbidity and mortality despite current medical and surgical treatment. The mechanics underlying aortic dissection are incompletely understood, and a further understanding of the relevant fluid and solid mechanics may yield not only a better appreciation of its pathogenesis, but also the development of improved diagnostic and therapeutic strategies. After illustrating some of the inadequacies with respect to the extant work on the mechanics of aortic dissection, we alternatively postulate that the clinical hemodynamic disturbances that render the aorta susceptible to the initiation of dissection are principally elevated maximum systolic and mean aortic blood pressure, whereas the hemodynamic disturbances that facilitate propagation of dissection are principally elevated pulse pressure and heart rate. Furthermore, abnormal aortic mechanical properties and/or geometry are requisite for dissection to occur. Specifically, we propose that the degree of anisotropy will directly influence the probability of future aortic dissection. Imaging of the aorta may provide information regarding aortic anisotropy and geometry, and in combination with a hemodynamic risk assessment, has the potential to be able to prospectively identify patients at high risk for future aortic dissection thereby facilitating prophylactic intervention. The aim of the paper is to identify the main mechanical issues that have a bearing on aortic dissection, and to suggest an appropriate mathematical model for describing the problem.     

基质金属蛋白酶基因多态性与主动脉夹层的研究进展*

摘要：主动脉夹层(Aortic dissection, AD)为最危险的主动脉疾病之一,病死率较高,且发病率呈逐年上升的趋势。越来越多的证据 表明遗传因素影响该疾病的发生及发展,基因多态性为该疾病的遗传易感因素之一。主动脉夹层患者可观察到主动脉中膜的退 化,当主动脉结构发生改变时,必然导致一系列的病理生理反应,进而影响其功能。细胞外基质（Extracellular matrix,ECM）是由弹 性纤维和胶原纤维组成的,可以保持主动脉管壁的稳定性。主动脉夹层的发生与ECM 的代谢平衡有关,降解ECM的酶为基质金 属蛋白酶（Matrix metalloproteinases,MMPs）,这种酶在主动脉的重塑过程中也发挥作用,与夹层的发生密切相关。单核苷酸多态 性(single nucleotide polymorphism,SNP)作为遗传学标记,可以预测该疾病的发生, 指导该疾病的临床研究方向,对于易感性较高 的患者可进行早期的预防及监测,在AD的预防及治疗方面发挥重大作用。本文对基质金属蛋白酶基因多态性与主动脉夹层之间 的关系做一综述。     

Surgical thimble for use in augmentation mammaplasty

A conveniently formed thimble has been created for use in dissection during augmentation mammaplasty and gynecomastia operations which forms a rigid extension to the surgeon's finger. With the aid of this instrument, which is fitted onto the third and partly onto the second phalanx of the index finger, the delicacy and maneuverability characteristics of digital dissection are on the whole retained and the surgeon avoids the use of traditional dissection instruments gripped in the hand, with which it is easy to exceed the desired limits of dissection creating nervous lesions and unequal pockets.     

基质金属蛋白酶基因多态性与主动脉夹层的研究进展

主动脉夹层（Aorticdissection,AD）为最危险的主动脉疾病之一,病死率较高,且发病率呈逐年上升的趋势。越来越多的证据表明遗传因素影响该疾病的发生及发展,基因多态性为该疾病的遗传易感因素之一。主动脉夹层患者可观察到主动脉中膜的退化,当主动脉结构发生改变时,必然导致一系列的病理生理反应,进而影响其功能。细胞外基质（Extracellularmatrix,ECM）是由弹性纤维和胶原纤维组成的,可以保持主动脉管壁的稳定性。主动脉夹层的发生与ECM的代谢平衡有关,降解ECM的酶为基质金属蛋白酶（Matrixmetalloproteinases,MMPs）,这种酶在主动脉的重塑过程中也发挥作用,与夹层的发生密切相关。单核苷酸多态性（singlenucleotidepolymorphism,SNP）作为遗传学标记,可以预测该疾病的发生,指导该疾病的临床研究方向,对于易感性较高的患者可进行早期的预防及监测,在AD的预防及治疗方面发挥重大作用。本文对基质金属蛋白酶基因多态性与主动脉夹层之间的关系做一综述．     

Neck dissections: radical to conservative

BACKGROUND: Neck dissection is an important surgical procedure for the management of metastatic nodal disease in the neck. The gold standard of neck nodal management has been the radical neck dissection. Any modification in the neck dissection is always compared with this standard. Over the last few decades, in order to alleviate the morbidity of radical neck dissection, several modifications and conservative procedures have been advocated. These procedures retain certain lymphatic or non-lymphatic structures and have been shown not to compromise oncological safety. METHODS: A literature search of the Medline was carried out for all articles on neck dissections. The articles were systematically reviewed to analyze and trace the evolution of neck dissection. These were then categorized to address the nomenclature, management of node positive and node negative neck including those who had received chemoradiation. RESULTS: The present article discusses the neck nodal nomenclature, the radical neck dissection, its modifications and migration to more conservative procedures and possible advances in the near future. CONCLUSION: Radical neck dissection is now replaced with modified radical neck dissections in most situations. Attempts are being made to replace modified radical neck dissections with selective neck dissections for early node positivity. Sentinel node biopsy is being studied to address the issue of node negative neck. More conservative surgeries are likely to replace the 'radical' surgeries of bygone era. This process is facilitated by earlier detection of the disease and better understanding of cancer biology.     

Planned neck dissection following chemo-radiotherapy in advanced HNSCC

BACKGROUND: Neck dissection has traditionally played an important role in the management of patients with regionally advanced head and neck squamous cell carcinoma (HNSCC) treated with radical radiotherapy alone. However, with the incorporation of chemotherapy in the therapeutic strategy for advanced HNSCC and resultant improvement in outcome the routine use of post chemo-radiotherapy neck dissection is being questioned. METHODS: Published data for this review was identified by systematically searching MEDLINE, CANCERLIT & EMBASE databases from 1995 until date with restriction to the English language. RESULTS: There is lack of high quality evidence on the role of planned neck dissection in advanced HNSCC treated with chemo-radiotherapy. A systematic literature search could identify only one small randomized controlled trial (Level I evidence) addressing this issue, albeit with major limitations. Upfront neck dissection followed by chemo-radiotherapy resulted in better disease-specific survival as compared to chemoradiation only. Several single arm prospective and retrospective reports were also identified with significant heterogeneity and often-contradictory conclusions. CONCLUSIONS: Planned neck dissection after radical chemo-radiotherapy achieves a high level of regional control, but its ultimate benefit is limited to a small subset of patients only. Unless there are better non-invasive ways to identify residual viable disease, the role of such neck dissection shall remain debatable. A large randomized controlled trial addressing this issue is needed to clarify its role and provide evidence-based answers.     

Increasing Thyroid Cancer Rate and the Extent of Thyroid Surgery in Korea

Background

It is evident that the rate of thyroid cancer is increasing throughout the world. One reason is increased detection of preclinical small cancers. However, it is not clear whether the increase in thyroid cancer rate is reducing the extent of thyroid surgeries. The purpose of this study was to evaluate the thyroid cancer rate and analyze recent changes in the extent of thyroid cancer surgeries in Korea.

Methods

An observational study was conducted using data from Korea’s Health Insurance Review and Assessment Service (HIRAS) for thyroidectomy with/without neck dissection, with 228,051 registered patients between 2007 and 2011. Data were categorized by the extent of surgery: unilateral thyroidectomy without neck dissection (UT), bilateral thyroidectomy or radical thyroidectomy without neck dissection (TT), any thyroidectomy with unilateral selective neck dissection (SND), any thyroidectomy with unilateral modified radical neck dissection (MRND), any thyroidectomy with unilateral radical neck dissection (RND), and any thyroidectomy with bilateral neck dissection (BND). Annual rate difference for each surgery was analyzed with a linear by linear association.

Results

The absolute numbers of total thyroid surgeries (UT+TT+SND+MRND+RND+BND) were increased from 28539 to 61481. The proportion of patients who underwent only thyroidectomy without neck dissection (UT+TT) decreased from 67.30% to 60.50%, whereas the proportion of patients who underwent neck dissection (SND+MRND+RND+BND) increased from 32.70% to 39.50% during the 5-year study period.

Conclusion

Despite the increase in rate of thyroid cancer due to earlier detection, increased rate of neck dissection was noted.     

Dissecting aortic aneurysm and contrast magnetic resonance angiography

The propose of the present work is to study the potential of the 3-D contrast MR-angiography (MRA) in diagnosis of aortic dissection. The studied group consisted of 45 patients who as expected might have aortic dissection. 15 patients was observed in dynamics after surgical treatment. Total number of me performed contrast-MRA was 72. MRA has been performed on 1.5T MR tomograph Magnetom Vision (Siemens) with the of ultrafast sequenses Fisp and turbo-flash. Aortic dissection was diagnosed in 18 patients. The method of ce-MRA enables to make a precise diagnose of acute and chronic aortic dissection. This method is used for a dynamic follow up of the patients after the performed surgery.     

Factors in the propagation of aortic dissections in canine thoracic aortas

Factors were examined which altered the propagation of aortic dissections in canine aortas. Thoracic aortas were removed from sacrificed dogs from the distal end of the arch to the diaphragm. An intimal tear was created at the proximal end of the aorta. The dissection was propagated using a pulsatile pressure system with no flow. The aorta was perfused with a dilute black paint solution, which allowed both video monitoring of the extension of the dissection and measurement of the dissection rate. The dependence of the dissection rate on the variables peak pressure, (dP/dt)max and intimal tear depth was examined. The dissection rate was found to be dependent on (dP/dt)max (p less than 0.005) and the intimal tear depth, expressed as a percentage of wall thickness (p less than 0.01), but not on the peak pressure or intimal tear length. The equation relating the significant variables was log (dissection rate) = (-0.034) X % tear depth +(1.89 +/- 0.56) X (dP/dt)max -(4.3 +/- 1.8); r = 78. Thus a higher (dP/dt)max was associated with a more rapid dissection rate and a deeper intimal tear was associated with a slower dissection rate.     

Spontaneous coronary artery dissection: long stenting in a patient with polycythemia vera

Spontaneous coronary artery dissection is a rare cause of myocardial ischemia or sudden cardiac death. We describe a patient with polycythemia vera and a chronic spontaneous coronary artery dissection who was treated with successful angioplasty and long stenting.     

Hybrid thoracic stent graft repair of a complex type B aortic dissection in a patient who presented three weeks after repair of a type a aortic dissection

Long-term management after repair of a type A aortic dissection includes aggressive medical therapy and routine surveillance with serial imaging to ensure thrombosis of the false lumen. Retained patency of the false lumen can lead to either the development of a false lumen aneurysm with a subsequent rupture or extension of dissection. Typically such events occur late, usually months after repair, and are treated with either a conventional one-stage open thoracoabdominal repair or a two-stage "elephant trunk" procedure. However, most patients who undergo such procedures experience major complications and the procedure-related mortality rate is high. We present a unique case of a 61-year-old woman who presented with a ruptured type B aortic dissection 3 weeks after repair of a type A aortic dissection. She underwent an emergent thoracotomy and primary repair of the ruptured aorta followed by concomitant arch debranching and thoracic stent graft placement. Simultaneous surgical debranching with a median sternotomy and endovascular repair with stent grafts is an attractive hybrid approach in patients who present with an acute rupture of a false lumen aneurysm soon after initial repair of an aortic dissection, a situation in which a conventional repair is not feasible. This report emphasizes that hybrid thoracic stent graft repair should be considered for such high-risk patients in the near future as it offers them relatively lower morbidity and mortality compared with what is seen with conventional repairs.     

Imaging of left main trauma during diagnostic cardiac catheterization with intravascular ultrasound

In this case report the occurrence of a catheter-induced coronary artery dissection is described. In our patient, angiography showed a mushroom-shaped exudate above the left main coronary artery. Intravascular ultrasound revealed a circular dissection with a huge false lumen connected to the true lumen by a small intimal tear. A brief review of the literature on catheter-induced coronary dissection is included. We believe that this case report provides a good illustration of the need for careful reviewing of indications for angiography. Although procedural risks are low, angiography remains an invasive diagnostic test with the potential to cause severe complications.     

Peer-Assisted Learning in a Gross Anatomy Dissection Course

Peer-assisted learning encourages students to participate more actively in the dissection process and promotes thoughtful dissection. We implemented peer-assisted dissection in 2012 and compared its effects on students’ self-assessments of learning and their academic achievement with those of faculty-led dissection. All subjects performed dissections after a lecture about upper-limb gross anatomy. Experimental group (n = 134) dissected a cadaver while guided by peer tutors who had prepared for the dissection in advance, and control group (n = 71) dissected a cadaver after the introduction by a faculty via prosection. Self-assessment scores regarding the learning objectives related to upper limbs were significantly higher in experimental group than in control group. Additionally, experimental group received significantly higher academic scores than did control group. The students in peer-assisted learning perceived themselves as having a better understanding of course content and achieved better academic results compared with those who participated in faculty-led dissection. Peer-assisted dissection contributed to self-perception and to the ability to retain and explain anatomical knowledge.     

Dissection properties of the human aortic media: an experimental study

Aortic dissection occurs frequently and is clinically challenging; the underlying mechanics remain unclear. The present study investigates the dissection properties of the media of 15 human abdominal aortas (AAs) by means of direct tension tests (n=8) and peeling tests (n=12). The direct tension test demonstrates the strength of the media in the radial direction, while the peeling test allows a steady-state investigation of the dissection propagation. To explore the development of irreversible microscopic changes during medial dissection, histological images (n=8) from four AAs at different peeling stages are prepared and analyzed. Direct tension tests of coin-shaped medial specimens result in a radial failure stress of 140.1+/-15.9 kPa (mean+/-SD, n=8). Peeling tests of rectangular-shaped medial strips along the circumferential and axial directions provide peeling force/width ratios of 22.9+/-2.9 mN/mm (n=5) and 34.8+/-15.5 mN/mm (n=7); the related dissection energies per reference area are 5.1+/-0.6 mJ/cm(2) and 7.6+/-2.7 mJ/cm(2), respectively. Although student's t-tests indicate that force/width values of both experimental tests are not significantly different (alpha=0.05, p=0.125), the strikingly higher resisting force/width obtained for the axial peeling tests is perhaps indicative of anisotropic dissection properties of the human aortic media. Peeling in the axial direction of the aorta generates a remarkably "rougher" dissection surface with respect to the surface generated by peeling in the circumferential direction. Histological analysis of the stressed specimens reveals that tissue damage spreads over approximately six to seven elastic laminae, which is about 15-18% of the thickness of the abdominal aortic media, which forms a pronounced cohesive zone at the dissection front.     

Acute myocardial infarction due to an acute type A aortic dissection involving the left main coronary artery

We report a case of anterior myocardial infarction due to a Stanford type A aortic dissection involving the left main trunk of the coronary artery. Acute myocardial infarction due to extension of an acute Stanford type A aortic dissection is an infrequent but devastating situation. In our case a spontaneous aortocoronary dissection involving the Valsalva sinus and the ascending aorta with a history of hypertension is the most plausible cause. Emergent aortic replacement and revascularisation was performed. (Neth Heart J 2007;15:263-4.)     

The effect of partial dissection of the zona pellucida on the fertilization of bovine oocytes in vitro and on the subsequent development of the embryos outside the body

Influence of partial zona dissection (PZD) on fertilization and cleavage of cow oocytes and on pre-implantation development of embryos obtained by this method was investigated. Decreased concentration of spermatozoa in less degree influenced on rates of fertilization and cleavage of oocytes with partial zona dissection than on intact eggs. The embryos obtained by method PZD can develop in vitro to blastocyst stage. However, their development is slowed down and presence of dissection in zona pellucida can result in premature hatching such blastocysts.     

Aortic dissection presenting as acute myocardial infarction: potential harm of antithrombin and antiplatelet therapy

In the treatment of acute myocardial infarction, antithrombin and antiplatelet therapy are indicated according to the current guidelines. When a patient presents with symptoms and signs of acute myocardial infarction, an extensive list of diagnoses should be considered. Because of the nonspecific symptoms of aortic dissection, the disease may be easily misdiagnosed. A high clinical suspicion of aortic dissection is therefore required. Once aortic dissection has been diagnosed, surgical intervention provides the only definitive treatment for these patients, regardless of antithrombin and antiplatelet therapy.     

Coronary artery dissection following blunt chest trauma: a case report

Coronary artery dissection following blunt chest trauma is rare. We report the case of a 43-year-old woman who was admitted with a subacute inferior myocardial infarction due to dissection of the right coronary artery. Ten days earlier, she had sustained a minimal chest trauma. The literature is reviewed and management is discussed.