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PubMed1983

Structure as revealed by airway dissection. A comparison of mammalian lungs.

Microdissection of mammalian pulmonary airways demonstrates branching patterns and provides precisely defined tissue samples for morphologic study. The dissections are performed on lung fixed by airway infusion at standard pressures. Using fine scissors and a high resolution dual-viewing dissecting microscope, extrapulmonary and intrapulmonary airways are dissected down their axial pathways. The plane of dissection is chosen to include as many minor daughter (side) branches as possible. Lungs from 5 species: sheep, goat, cat, rabbit, and bonnet monkey have been dissected, photographed, successive generations numbered, and pieces of tissue processed for LM, TEM, and SEM. Branching patterns differ between lobes (cranial versus caudal) of the same species and between the same lobe in different species. Marked differences in epithelial population distribution within the airway tree are found between the same lobe of different species (i.e., cranial lobes of rabbit and sheep) and between different lobes in the same species (i.e., cranial and caudal lobes of the sheep). The dissection approach to pulmonary airway morphologic studies provides specimens of precisely defined branching history, generation number, and anatomic position within regions of the lung and within specific segments. This allows studies that compare: (1) different airway generations in the same pathway, (2) bifurcation points and the airway segments between them, (3) terminal airways of differing pathway lengths and numbers of branching, (4) terminal airways of different regions of same lobe, (5) same airway generations in different lobes, and (6) same airway generations from animal to animal and species to species.

Animals↗

PubMed1994

Combined type B aortic dissection and fusiform abdominal aortic aneurysm. Case reports.

Two patients are described with a combined type B aortic dissection and a fusiform abdominal aortic aneurysm, the dissection not involving the aneurysm. In a seventy-year-old man a type B aortic dissection and a large abdominal aneurysm were found. An infrarenal aortic bifurcation graft was inserted. He died fifteen months later of cardiogenic shock. In a sixty-six-year-old man diagnosis of a primary aortoduodenal fistula was made together with a limited type B dissection. A straight aortic interposition graft was inserted. He died eleven months later of the complications of a secondary aortoduodenal fistula. Although combination of aortic dissection and abdominal aneurysm is a rare occurrence, conservative management of the aortic dissection and interposition graft for the abdominal aneurysm was successful as initial treatment in these 2 patients.

Aged↗

PubMedDate not supplied

Home temporal bone dissection: anatomic approaches to ear surgery.

The anatomy of the temporal bone can only be mastered by repeated surgical and anatomic dissections. For the otolaryngologist who does not have access to laboratory facilities, a technique for dissecting temporal bones at home using readily available and inexpensive equipment is described. The basic home dissecting kit consists of dry temporal bones, a high-speed hobby drill, dental burrs, loupes, and paints. The preparation of temporal bones for dissection and approaches to anatomic, transmastoid, transcanal, and neuro-otologic dissections are presented. The relative benefits of home dissection in learning temporal bone anatomy and developing new surgical approaches, such as a transcanal-transcochlear approach to the internal auditory canal, are discussed.

Dissection↗

PubMed2006

Dissection of the extracranial vertebral artery: clinical findings and early noninvasive diagnosis in 24 patients.

Dissection of cervical arteries causes ischemic stroke in young adults. This reports the clinical, ultrasonographic, and neuroradiological findings in 24 patients with 28 vertebral artery dissections in the neck (4 occurring bilaterally). In 20 patients (83%), the dissection was temporally related to trauma. No patients had an underlying vascular disease, for example, atherosclerosis or fibromuscular dysplasia. In all, the major initial manifestation was pain in the occipital or neck region. The next most common symptoms were vertigo and nausea (in 17 patients). Clinical manifestations were vertebrobasilar transient ischemic attack (TIA) (5 patients: in 2 patients vestibulocerebellar TIA, in 1 patient visual TIA, in 1 patient motor TIA, and in 1 patient brain stem TIA with perioral paresthesia), cerebellar infarction (10 patients, in 4 patients bilateral), brainstem infarction (5 patients), posterior cerebral artery territory infarction (1 patient), and multiple vertebrobasilar ischemic lesions (3 patients). Typical angiographic findings were irregular narrowing of the vessel lumen or a tapering stenosis with distal occlusion. Magnetic resonance imaging showed a thickened vessel wall with hematoma signal at the site of the dissection. Duplex color-flow imaging was valuable for the early diagnosis of extracranial vertebral artery dissection and for follow-up examinations. The distal V1- and the proximal V2-segment (at the level of C6 vertebra) was the most frequent localization of dissections (in 43%). The outcome was favorable except for 2 patients with basilar artery occlusion. Embolism to the basilar artery may be avoided by early administration of anticoagulants.

Adolescent↗

PubMed2004

Aortic dissection: a dreaded disease with many faces.

Aortic dissection is a relatively uncommon but catastrophic illness classically thought to present with acute, sharp, chest pain with radiation to the back. However, aortic dissection can manifest in a number of different ways that include congestive heart failure, inferior myocardial infarction, stroke, focal pulse and neurologic deficits, abdominal pain, or acute renal failure. According to some studies, only about 80% of patients with type A dissection present with severe anterior chest pain, and only about 60% describe their pain as being sharp. Another series reports that treating clinicians fail to initially entertain the diagnosis of aortic dissection in up to 35% of cases. Many patients later found to have aortic dissection are initially suspected to have other conditions such as acute coronary syndrome, pericarditis, pulmonary embolism, or even cholecystitis. In this article we present a case of an unusual presentation of aortic dissection and a review of this condition.

Aortic Dissection↗

PubMed2003

Relationship of intimal flap position to endovascular treatment of malperfusion syndromes in aortic dissection.

PURPOSE: To propose a classification system based on the position and extension of the intimal flap to assist in the endovascular repair of aortic dissection complicated by a malperfusion syndrome. METHODS: Forty-one patients (34 men; mean age 58 years, range 22-78) with 19 type A and 22 type B dissections complicated by a malperfusion syndrome were treated with stenting, fenestration, or both for the peripheral ischemia. A retrospective review of the preprocedural imaging studies (computed tomographic angiography and arteriography) was performed to determine and categorize the position of the aortic intimal flap. In type 1, the flap was either parallel to or perpendicular to the origin of the malperfused collateral artery; type 2 referred to extension of the dissection into the collateral vessel, while type 3 represented the presence or absence of an avulsed branch ostium. RESULTS: Patients treated with stenting (n=19) alone had type 2 or type 3 arterial dissections, whereas the 12 patients who were treated with fenestration alone had type 1 lesions. Ten patients treated with stenting and fenestration had arterial lesions in which a type 1 dissection was associated with types 2 or 3. CONCLUSIONS: This appearance-based imaging approach combined with the symptoms of malperfusion syndromes during aortic dissection can help guide the endovascular treatment strategy.

Adult↗

PubMed2003

Endovascular management of symptomatic vertebral artery dissection achieved using stent angioplasty and emboli protection device.

Extracranial vertebral artery (VA) dissection may lead to significant arterial stenosis, occlusion, or pseudoaneurysm formation with subsequent hemodynamic and embolic infarcts. To prevent thromboembolic complications, anticoagulation with intravenous heparin followed by oral warfarin has been recommended for all patients with acute dissections, regardless of the type of symptoms, unless there are contra-indications. Nevertheless, anticoagulation is not innocuous, may be contra-indicated or may be ineffective to prevent symptoms or dissection progression. Because it is effective and less invasive than other surgical procedures, endovascular treatment of VA dissection has recently attracted interest. We present a case of a traumatic VA dissection, presenting with multiple embolic infarctions that was managed with protected stent-assisted angioplasty. Protected stent-assisted VA angioplasty has not been previously reported and appears to be a safe, effective and immediate method of restoring vessel lumen integrity and should be considered in the therapy of selected cases of VA dissection.

Adolescent↗

PubMed2004

Branch vessel complications are increased in aortic dissection patients with renal insufficiency.

Morbidity and mortality from aortic dissection remain high despite advances in diagnosis and treatment. Simple markers to identify patients at high risk for non-aortic complications of dissection are lacking. We investigated the effect of renal insufficiency on the presentation, complications, and outcome of patients with acute aortic dissection. We evaluated 638 patients with type A and 365 patients with type B aortic dissection enrolled in the International Registry of Acute Aortic Dissection (IRAD) between January 1996 and December 2000. Chi-squared and Student's ttesting were performed to identify the effect of renal insufficiency on patient presentation, management, and outcome. Patients with renal insufficiency more often required nitroprusside for blood pressure control (type A: 40.7% vs 31.1%, p = 0.049; type B: 66.7% vs 37.3, p = 0.0001) and had a greater risk of mesenteric ischemia (type A: 10.7% vs 1.4%, p < 0.0001; type B: 17.7% vs 3.0%, p < 0.0001). In conclusion, aortic dissection patients with renal insufficiency are at increased risk for drug-resistant hypertension and aortic branch vessel compromise. Routine measurement of serum creatinine provides a readily accessible clinical marker for important complications. Upon recognition, renal impairment indicates a need for close monitoring, aggressive blood pressure control, and evaluation of aortic branch vessel circulations.

Acute Disease↗

PubMed2004

Pulmonary artery obstruction caused by thoracic aortic dissection: a case with unique pathological findings.

Pulmonary artery obstruction is a rare complication of acute thoracic aortic dissection. A 74-year-old woman was admitted to hospital with respiratory distress. Computed tomography scan showed right pulmonary artery occlusion and a thoracic aortic dissection of the Stanford A type. Lung perfusion scan revealed a defect in the entire right lung field. These findings mimicked acute pulmonary thromboembolism accompanying aortic dissection. On the other hand, pulmonary angiography revealed a round smooth defect of the right pulmonary artery, indicating an extrinsic compression. The patient finally died of cardiac tamponade. Autopsy disclosed that the right pulmonary artery was compressed by a hematoma in the adventitial space around the pulmonary artery. Such a mechanism of pulmonary artery obstruction caused by acute aortic dissection is unique, and is distinct from that caused by chronic non-dissecting aortic aneurysms, which themselves compress the pulmonary arteries. This complication inevitably follows aortic rupture; therefore, emergency operation to repair the dissected aorta must be performed to avoid the following catastrophic event.

Aged↗

PubMed2001

Long-term prognosis of acute aortic dissection with medical treatment: a survey of 263 unoperated patients.

Between 1973 and 1998, 263 patients with acute aortic dissection were medically treated only. They were divided into 4 groups: Stanford type A and B with open false lumen (open) or with early thrombosed false lumen (thrombosed). An event was defined as death by dissection or re-dissection. Gender, age, maximum diameter of dissected aorta and presence of shock at onset were examined as risk factors. In the open false lumen group, the presence of shock was associated with the event. During the chronic period, the diameter of the aorta was associated with prognosis in open type B dissection. The rate of event was higher in the open type A and B groups than in the thrombosed type A and B groups; however, there was no difference in the event-free rate between types A and B in patients surviving the acute period. The prognosis of medically treated dissecting aorta was not poor in patients with type B or with early thrombosed false lumen. The presence of shock at onset with open false lumen and the diameter of the aorta (> or =40 mm) in type B were significantly correlated with a poor prognosis.

Aged↗

PubMed1987

The efferent supply of the trapezius muscle: a neuroanatomic basis for the preservation of shoulder function during neck dissection.

The hypothesis that there is an alternative motor input to the trapezius muscle through cervical spinal nerves is evaluated through a review of the literature and through experimental studies performed by the author. Electrophysiologic testing of the spinal accessory nerve and of the ventral rami of the cervical spinal nerves was performed in cats and humans. These studies indicated that motor potentials recorded in the trapezius muscle after stimulation of the ventral rami of cervical spinal nerves in general represented the spread of current to the contiguous portions of the spinal accessory nerve or directly to the trapezius muscle. Rarely did there seem to be evidence of motor innervation to the upper and lower trapezius by fibers conveyed by the ventral rami of cervical spinal nerves. The predominant motor input to the trapezius muscle is through the spinal accessory nerve. Subjective evaluation, objective strength testing, and electromyographic evaluation were performed on patients who had undergone neck dissections. Three types of neck dissection were employed. These were modified neck dissection with preservation of the spinal accessory nerve, radical neck dissection with sacrifice of the spinal accessory nerve, and reconstruction using a cable graft and classical radical neck dissection. Regarding all of the methods of evaluation and comparison, the patients who retained function of the spinal accessory nerve in the postoperative period fared better than those who had a classical radical neck dissection with sacrifice of the spinal accessory nerve. This again supports the concept that the most important and predominant motor supply to the trapezius muscle is through the spinal accessory nerve. All of this information was used to construct a model of the spinal portion of the accessory nerve and of the innervation of the trapezius muscle. The clinical implications of this model are stated.

Animals↗

PubMed2001

Unusual complication of retrograde dissection to the coronary sinus of valsalva during percutaneous revascularization: a single-center experience and literature review.

BACKGROUND: While coronary dissection, which is one of the most frequently occurring complications during interventional procedures, has various forms, extensive coronary dissection retrograde to the coronary sinus of Valsalva (CSV) is very rarely observed. METHODS AND RESULTS: Within the last 5 years, we retrospectively reviewed our experience with 4,700 consecutive patients who underwent angioplasty procedures, 7 of whom (0.15%) developed extensive coronary dissection retrograde to the CSV. Six of the seven patients developed retrograde dissection of the right CSV during angioplasty to the right coronary artery. One of the seven patents developed retrograde dissection of the left CSV during angioplasty to the left anterior descending artery. Retrograde dissection, which extended to the ascending aorta in two patients, was observed by transthoracic echocardiography and surgical findings, respectively. Five patients were successfully treated by coronary stenting. However, this complication caused four patients to have acute myocardial infarctions, resulting in emergency surgery for one patient and in-hospital death for another. CONCLUSIONS: Our experience increased our understanding of this very rare complication. However, this complication may be life threatening, and patients in this clinical setting may have a potential risk for acute myocardial infarction, emergency surgery, or even sudden cardiac death. Therefore, it is important to learn how to promptly diagnose and manage this complication.

Aortic Dissection↗

PubMed2005

Utilization of a double-wire technique to treat long extended spiral dissection of the right coronary artery. Evaluation of incidence and mechanisms.

While coronary artery dissection caused by a guiding catheter, which is one of the most commonly occurring complications during diagnostic cardiac catheterization or coronary intervention, has various forms, extensive antegrade and retrograde dissections of the right coronary artery (RCA) are rarely observed during these procedures. Within the last three years, we retrospectively reviewed our experience with 12,600 consecutive patients who underwent either diagnostic cardiac catheterization or coronary angioplasty, and found that 17 (0.14%) of the patients displayed extensive antegrade and retrograde RCA dissection. The antegrade dissection always propagated to the distal RCA either on bifurcation of the posterior descending artery and posterolateral artery (PLA) or to the proximal PLA. The retrograde dissection was always observed close to the ostium of the RCA or extending to the ostium of the RCA. TIMI-0 flow in the RCA was immediately observed in all the patients. Chest pain associated with an electrocardiogram showing ST-segment elevation was soon observed in most of the patients. The true lumen could be entered successfully using a single wire in 8 of 17 patients. However, a double-wire technique was required for 7 patients. This technique involved first advancing a wire along to the false lumen and then pulling back the guiding catheter away from the ostium of the RCA for a few millimeters followed by anchoring with the wire. Another wire was then gently inserted into the true lumen from the dissection entrance point, which was located near or at the ostium of RCA, and carefully advanced to the distal RCA. Coronary stenting was successfully deployed in 15 patients. However, the procedure failed in 2 patients. Furthermore, this complication caused 7 patients to have acute myocardial infarctions, 2 patients to develop atrial fibrillation, and I to die from ischemic enterocolitis due to cardiac embolism after 7 months of follow-up. In conclusion, with an increase in experience, we now better understand this complication. However, this complication, which is a formidable challenge for coronary intervention, may be a life-threatening complication, and patients with this complication may face the potential risk of a nonfatal myocardial infarction, or even a long-term fatal outcome in the long-term. Accordingly, it is important to learn how to promptly manage this complication.

Aortic Dissection↗

PubMed1998

Further delineation of aortic dilation, dissection, and rupture in patients with Turner syndrome.

OBJECTIVE: Although cardiovascular malformations (CVMs) are well-recognized congenital anomalies in Turner syndrome, aortic dilation and dissection are less common and less familiar. Most of the relevant literature is limited to single cases reports or small series. We sought to increase the information available about the frequency and characteristics of aortic dilation in patients with Turner syndrome. DESIGN: A 1-page survey of cardiac abnormalities, including aortic dilation, was mailed to approximately 1000 (1040 verified) members of the Turner Syndrome Society as an enclosure in the June 1997 newsletter. We also conducted a literature review. PARTICIPANTS: A total of 245 patients or families of patient members of the Turner Syndrome Society responded to the survey ( approximately 24% response rate). RESULTS: A CVM was reported in 120 of 232 (52%) respondents to this questionnaire. Obstructive lesions of the left side of the heart predominated and included bicuspid aortic valve (38%) and coarctation (41%). Aortic dilation was reported in at least 15 of 237 respondents (6.3%; 95% confidence interval: 3.6%-10.3%); 2 of 15 (13%) had dissection. Twelve of 15 (80%) patients had an associated risk factor for aortic dilation such as a CVM or hypertension. The 3 (20%) patients who did not have a CVM or hypertension were all younger than 21 years. In the entire group with aortic dilation, 10 of 15 (67%) patients were younger than 21 years. All patients with aortic dilation had involvement of the ascending aorta, and 2 had additional involvement of the descending aorta distal to a repaired coarctation. An update of the literature revealed 68 patients with aortic dilation, dissection, or rupture. An associated CVM or hypertension was reported in 53 of 59 (90%) informative patients. At least 6 (10%) had no predisposing risk factor (information was inadequate for 9 of 68 patients). The following patterns of aortic involvement were identified: ascending +/- descending aorta with coarctation (14); ascending +/- descending aorta without coarctation (39); descending aorta with coarctation (3); descending thoracic or abdominal aorta without coarctation (4); and unspecified (8). Dissection or rupture was reported in 42/68 (62%). Two reported patients died suddenly from aortic dissection in the third trimester of assisted pregnancy. At least 20 (29%) patients were younger than 21 years. One of the 6 (17%) patients with isolated aortic dilation was in this younger group. CONCLUSIONS: More information is needed about the frequency and natural history of aortic dilation in Turner syndrome. This work contributes new patient data and increases the literature review. Despite the well-recognized limitations of self-reporting, this survey detected aortic dilation with or without dissection in approximately 6% of patients with Turner syndrome. Although rare, this is a potentially catastrophic occurrence, warranting greater awareness among health professionals. In this study and the literature, the vast majority of patients with aortic dilation have an associated risk factor such as a CVM, typically bicuspid aortic valve or coarctation, or systemic hypertension. These patients represent a higher risk group that should be followed appropriately, usually under the direction of a cardiologist. Patients undergoing assisted pregnancy also should be evaluated closely. It is generally accepted that at the time of diagnosis of Turner syndrome, all patients should have a complete cardiology evaluation including echocardiography. The small number of patients with aortic dilation without a CVM, who would not be under the long-term care of a cardiologist, makes it prudent to screen all patients with Turner syndrome for this potentially lethal abnormality. The specific timing for this screening is controversial. Our recommendations for prospective imaging do not represent a rigid standard of care.

Adolescent↗

PubMed1994

Correlation between the layer of an intimal tear and the progression of aortic dissection.

Thoracic aortas isolated from dogs were evaluated to determine the correlation between the depth of an intimal tear and the progression of aortic dissection. Thoracic aortas obtained from 99 adult mongrel dogs were used. An intimal tear (aortic pocket) was created on the aortic wall and the aorta was connected in series to a closed circuit (150 mmHg/100 mmHg and 60 beats/min). The progression of the dissection was most notable in the aortic pocket prepared in the first one-third of the external media (87.5%). There was no correlation however between the width of the pocket and the progression of dissection. Examinations of samples from surgical patients have shown that dissection usually progresses at the same site. This has been attributed to the diseased media. Our results demonstrated that dissection occurred almost always at the same site without any medial changes suggesting that whether dissection develops or not likely depends upon whether the intimal tear reaches the first one-third of the external media or not.

Aortic Dissection↗

PubMed1998

Effects of endoluminal stent-grafts on acute aortic dissection in dogs.

Acute aortic dissection is a life-threatening condition, and may be treated with aggressive hypotensive drug therapy, but emergency surgery is often necessary. We evaluated the effectiveness of stent-grafts for the treatment of acute aortic dissection. Aortic dissection was surgically created in the descending thoracic aorta in 20 adult mongrel dogs. A stent-graft was inserted in the entry position. The tested animals were divided into 4 groups based on re-entry type and blood pressure alteration rate (AR) after acute aortic dissection. After insertion of the stent, the following results were observed: a) AR improved; b) proximal descending aorta and superior mesenteric arterial flows increased; c) cardiac function improved; and d) the dissecting aortic diameter decreased in the presence of pressure gradient group. From these results, insertion of a stent-graft to treat acute aortic dissection was judged to be effective.

Acute Disease↗

PubMed2004

Histological study of the normal vertebral artery--etiology of dissecting aneurysms.

Histological evaluation of dissecting aneurysms of the cerebral arteries has suggested that defects in the internal elastic lamina (IEL) induce dissection of the arterial wall. Dissecting aneurysms occur most frequently in the vertebral artery (VA). The present study examined sections of the normal VA to elucidate the mechanisms of arterial dissection. Bilateral VAs (20 vessels) were obtained from 10 patients who died of causes other than intracranial lesions. The VAs were detached from the VA union to the site 10 mm proximal from the point penetrating the dura mater. The VAs were cut at 5-mm intervals, and each segment was observed using modified Masson's trichrome staining for elastic fibers. The thickness of the media and adventitia significantly thinned after the origin of the posterior inferior cerebellar artery (PICA). IEL defects were observed at 35 sites in 11 vessels from six subjects. There was a high incidence of IEL defects in the extradural portion and near the origin of the PICA, areas frequently involved in arterial dissection. There was a high incidence of intimal thinning at areas of IEL defects (19 of 35), and thinning was particularly marked distal to the origin of the PICA. In the absence of intimal thickening, the vascular strength at the site of IEL defects may be reduced, which would promote the occurrence and progression of arterial dissection.

Adult↗

PubMed1983

CT recognition of acute aortic dissection.

Twenty-six patients with suspected acute aortic dissection were investigated using computed tomography (CT) as the primary mode of investigation. The diagnosis was controlled by aortography or surgery or both. There were no false-positive or false-negative studies using CT. Aortography was performed on 19 of the 21 patients with aortic dissection and was positive in each instance. However, in two illustrated cases, CT indicated proximal or type A aortic dissection, whereas the corresponding aortograms indicated distal or type B aortic dissection. In two of the 21 acute aortic dissections, only CT was performed, and in both instances surgical confirmation was obtained. The results suggest that CT is at least as accurate as aortography in the diagnosis of acute aortic dissection.

Acute Disease↗