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Ownership of knowledge--the role of patents in pharmaceutical R&D.

Both the public and the private sectors contribute to research and development (R&D) in pharmaceuticals. The public sector originates many of the discoveries of new drugs. The private sector, which focuses on development, is heavily reliant on patents. Though patents are presumed to reward genuine inventions, lax rules on patentability and shortcomings in procedures permit protection to be obtained on a myriad of minor developments. These patents, though weak and possibly invalid in many cases, are used to restrain competition and delay the entry of generic competition. Developing countries should design and implement their patent laws so as to prevent strategic patenting and promote competition and access to medicines.

Developed Countries↗

The use of Food and Drug Administration 510(k) notifications in patent litigation.

The U.S. Food and Drug Administration (FDA) 510(k) approval process provides medical device companies with the ability to market a device after the company establishes that the device to the marketed is "substantially equivalent" to one or more predicate devices. Companies that submit 510(k) notifications should be aware, however, that a 510(k) notification is a public document that may later reappear as evidence in patent litigation. Courts have considered 510(k) notifications to be relevant evidence in determining direct and contributory infringement, patent invalidity, and patent unenforceability due to inequitable conduct before the U.S. Patent and Trademark Office (USPTO). In one case, the court held that a substantial equivalence determination by FDA constituted evidence that can be "construed as an admission of infringement." The court also has relied on a 510(k) notification to support a finding of personal liability for a corporate officer who signed the 510(k) notification to be evidence of willful and deliberate conduct, and have awarded treble damages and reasonable attorney's fees to the prevailing party. The potential for increased risk in patent litigation is important for practitioners in the medical device industry, because more than seventy-five percent of medical devices are approved for marketing through the 510(k) process. This article reviews a number of patent cases in which a court has admitted a 510(k) notification as relevant evidence, and proposes general strategies for avoiding these situations.

Device Approval↗

Stenting the patent arterial duct to increase pulmonary blood flow.

BACKGROUND: Use of surgically created aoropulmonary shunt is well-established for improving pulmonary blood flow in infants with critical reduction in pulmonary blood flow. Recently, stenting the patent ductus arteriosus has emerged as an alternative in selected infants with congenital heart disease and reduced pulmonary blood flow. METHODS AND RESULTS: We reviewed records of consecutive infants undergoing stenting of patent ductus arteriosus between August 2003 and October 2005 at our institution. Two of 12 patients underwent patent ductus arteriosus stenting to facilitate preparation of left ventricle for transposition with intact septum. We report the case selection, technique, immediate and short-term follow-up outcome in the remaining 10 patients [median age: 16 days (range 4-290 days): weight 2.7 kg (range 2-6 kg)] with reduced pulmonary blood flow who underwent stenting of patent ductus arteriosus as an alternative to conventional surgical aortopulmonary shunts. Five of the 6 newborns were prostaglandin-dependent and 4 had previously undergone guidewire perforation of the pulmonary valve (n=2) or balloon dilation (n=2). Successful stent implantation was accomplished in all with no major patient-related complication (median fluoroscopy time: 18.6 min; range: 7.7-72 min). The intensive care unit and hospital stays were prolonged in 3 patients because of sepsis (n=2) and pulmonary over-circulation with sepsis (n=1). On follow-up (median 5.5 months; range 1-19 months) all implanted stents were patent. One patient underwent re-dilation of the implanted stent for declining saturations. CONCLUSIONS: The immediate and short-term follow-up results of stenting of the patent arterial duct, as an alternative to the surgical aortopulmonary shunt in carefully selected newborns and infants is encouraging.

Blood Flow Velocity↗

Diagnostic testing of genetic disorders: limiting the scope of patent claims through disclosure requirements.

The breadth of claims in patents relating to genetic inventions has been controversial for some time. Possible adverse effects of broad claims include inhibiting research and higher costs, restricting patient access to genetic testing. The Australian Law Reform Commission's Report on Genes and Ingenuity--Gene Patenting and Human Health examined this issue, and concluded that the existing disclosure requirements contained in s 40 of the Patents Act 1990 (Cth) provide adequate mechanisms to control the breadth of claims. However, application of these requirements may be problematical in practice due to lack of relevant case law to provide guidance to patent examiners. It has been suggested that this deficit in direct judicial guidance can be obviated by developing appropriate analogies with other chemical systems in decided cases. This article focuses on gene-based diagnostic patents for human diseases, such as those held by Myriad Genetics for testing predisposition towards breast and ovarian cancer using the gene BRCA1. By examining the application of disclosure requirement by courts in genetic and non-genetic chemical inventions, it is possible to provide insight into how this might be applied by courts considering the validity of patent claims for diagnostic testing methods based on mutations in a gene such as BRCA1.

Australia↗

Phototherapy effect on the incidence of patent ductus arteriosus in premature infants: prevention with chest shielding.

Patent ductus arteriosus is common among premature neonates, especially those with birth weights less than 1,500 g. In vitro, room light inhibits the contraction of immature piglet's ductal rings. Because phototherapy is used frequently from the first days of life to treat jaundice in preterm neonates, we compared the occurrence of patent ductus arteriosus among premature infants exposed to this intense light source with those whose chests were shielded. Seventy-four babies with respiratory distress syndrome were randomly assigned to either a treatment group (chest shielded with aluminum foil while on phototherapy, 36 babies) or control group (no shield, 38 babies). All were on radiant warmers, received mechanical ventilation for respiratory distress syndrome, and phototherapy (Air Shields model PTU 78-1) from day 1 of life. Irradiance was maintained at greater than 4.0 microW/cm2/nm in all cases. Although both groups had similar birth weights, gestational ages, severity of respiratory distress syndrome, intravenous fluid intake, and duration of phototherapy, the incidence of patent ductus arteriosus was significantly less in the shield group (shield 11/36 v No shield 23/38; P = .009). Patent ductus arteriosus murmurs developed in shielded patients at a later date, they required less vigorous treatment (ie, indomethacin), and they had shorter hospitalizations (74 v 85 days; P less than .05). The significant reduction of patent ductus arteriosus with shielding suggests that phototherapy may play a role in the occurrence of patent ductus arteriosus in premature infants. Shielding may be a practical method to decrease this common complication should this initial observation be confirmed.

Ductus Arteriosus, Patent↗

Patenting human beings: do sub-human creatures deserve constitutional protection?

The availability of patents for genetically altered animals raises questions about the patentability of human beings. Genetic research will produce beings who fall halfway between what we currently think of as "animal" and "human." It is unclear on which side of the legal line these creatures will fall. In April 1988, Congress revised the Patent Act with a statement that human beings are not to be considered patentable subject matter. Congress, however, failed to supply a definition of the term "human being." A definition will clarify the legal status of sub-human creatures. The author addresses this problem and proposes a definition of "human being" as an amendment to the Patent Act.

Animals↗

Importance of a patent infarct-related artery for hospital and late survival after direct coronary angioplasty for acute myocardial infarction.

The importance of a patent infarct-related artery (IRA) for hospital and late survival was examined in 383 patients with acute myocardial infarction treated with direct coronary angioplasty. At hospital discharge, 317 of 348 patients (91%) had a patent IRA and mean follow-up left ventricular (LV) ejection fraction (EF) was 58%. Cardiac survival after hospital discharge at 1, 3 and 6 years was 99, 95 and 90%. Patency of the IRA was the most important determinant of hospital mortality: patent versus occluded IRA, 5 vs 39% mortality, p less than 0.001. Follow-up LVEF was the most important determinant of late cardiac mortality: follow-up LVEF greater than or equal to 45 versus less than 45%, 2 versus 24% mortality, p less than 0.001. Patency of the IRA was not a significant predictor of late cardiac mortality in the group as a whole: patent versus occluded IRA, 4.7 versus 6.5% mortality, p = 0.67. In the subgroup of patients with depressed initial LVEF less than 45%, patency was a significant predictor of late cardiac mortality: patent versus occluded IRA, 9.2 versus 40% mortality, p = 0.03. Patients with a patent IRA had better recovery of LV function than patients with an occluded IRA (follow-up LVEF 58.5 versus 47.6%, p less than 0.001). When late cardiac mortality was adjusted for differences in follow-up LVEF, patency was no longer a significant predictor of late mortality. Our results indicate patency of the IRA is the most important determinant of hospital survival, and LV function (measured after recovery) is the most important determinant of late cardiac survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Significance of left-sided heart disease for the detection of patent foramen ovale by transesophageal contrast echocardiography.

Detection of patent foramen ovale by contrast echocardiography is based on transient inversion (right atrial pressure higher than left atrial pressure) of the interatrial pressure gradient. Therefore, the presence of left-sided heart disease with potential elevation of left atrial pressure might obscure the diagnosis of patent foramen ovale. Accordingly, 150 patients (88 men, 62 women; mean age 51.7 +/- 15.2 years) were evaluated for a patent foramen ovale by transesophageal contrast echocardiography. Additionally, atrial septal motion during normal respiration and during the Valsalva maneuver was analyzed. Patency of the foramen ovale was observed in 20 (27%) of 74 patients without left-sided heart disease and with previous arterial embolism, in none (0%) of 25 patients with left-sided heart disease and embolism, in 7 (39%) of 18 patients without left-sided heart disease and without embolism and in 3 (9%) of 33 patients with left-sided heart disease and without embolism. The detection rate of patent foramen ovale was lower in patients with than without left-sided heart disease (5% vs. 29%, p = 0.0007) but was similar in patients with and without embolism (20% vs. 19.5%, p = NS). Abnormal atrial septal motion was more frequently observed in patients with left-sided heart disease (p = 0.0003) and was inversely correlated to detection of patent foramen ovale (p = 0.0003). Multivariate analysis revealed an independent association between the absence of left-sided heart disease and the detection of patent foramen ovale (p = 0.0003). These data suggest that in patients with left-sided heart disease, patency of the foramen ovale may be missed even by transesophageal contrast echocardiography.

Adult↗

Femoral vein delivery of contrast medium enhances transthoracic echocardiographic detection of patent foramen ovale.

OBJECTIVES: We postulated that femoral vein delivery of contrast medium because of streaming, might enhance precordial echocardiographic detection of patent foramen ovale. BACKGROUND: Although precordial contrast echocardiography is widely used to diagnose patent foramen ovale, this method is limited by poor sensitivity. Previous investigators have demonstrated enhanced detection of atrial defects by the dye-dilution technique after delivery of contrast medium into the inferior rather than the superior vena cava. METHODS: Transthoracic contrast examinations were performed in a randomly selected group of 70 patients (without previous history of cerebral or systemic embolus) undergoing cardiac catheterization. Paired contrast agent injections (10 ml dextrose in water/0.25 ml air) were administered from an upper extremity vein and femoral vein in each patient during spontaneous respiration, cough and Valsalva maneuvers. Studies were interpreted by an experienced echocardiographer unaware of the sequence and site of injections. Positive studies were semiquantitatively graded from +1 (minimal left ventricular opacification) to +4 (intense left ventricular opacification). Catheterization and echocardiographic assessment of patent foramen ovale were compared in 21 subjects. RESULTS: Patent foramen ovale was detected significantly more often during femoral vein versus upper extremity contrast delivery (23 of 70 patients [prevalence 33%] vs. 9 of 70 patients [prevalence 13%], p < 0.001). The intensity of left ventricular opacification was also greater during femoral vein contrast injection. Precordial echocardiography combined with femoral contrast delivery was significantly more sensitive than cardiac catheterization for assessment of patent foramen ovale (8 of 21 patients vs. 2 of 21 patients, p < 0.05). CONCLUSIONS: Femoral vein contrast delivery significantly enhances the ability of precordial contrast echocardiography to diagnose patent foramen ovale. Physiologic patency of the foramen ovale is more common (prevalence 33%) than previously documented.

Arm↗

Effects of the patent false lumen on the long-term outcome of type B acute aortic dissection.

OBJECTIVE: To determine the most effective treatment, we performed a detailed comparative study of the clinical course of patients with type B aortic dissection with a patent or thrombosed false lumen who did not undergo surgery in the acute period. We examined the effect of patency of the false lumen on outcome. METHODS: Computed tomography scans of 138 patients with type B acute aortic dissection were reviewed. Of 138 patients, 110 were medically treated and survived the acute period. We focused on the outcome of these 110 patients, 62 with medically treated thrombosed false lumen (thrombosed group) and 48 with medically treated patent false lumen (patent group). We investigated factors influencing outcome among the 110 patients. The follow-up period was up to 10 years after the onset of aortic dissection. The three study endpoints were death from any cause, dissection-related death (aortic rupture, perioperative death, or death due to organ ischemia), and a dissection-related event (aortic rupture or surgery). In the patent group, we investigated factors influencing long-term outcome. RESULTS: Patency of the false lumen was an independent risk factor for dissection-related death (P = 0.038, hazard ratio=5.6, confidence interval=1.1-28) and for a dissection-related event (P = 0.000, hazard ratio=7.6, confidence interval=2.7-22) but not for death from any cause (P = 0.769, hazard ratio=1.2, confidence interval=0.45-2.91). In the patent group, location of the most dilated aortic segment at the distal arch was an independent risk factor for dissection-related death (P = 0.026, hazard ratio=13.6, confidence interval=1.4-135) and for a dissection-related event (P = 0.048, hazard ratio=2.6, confidence interval=1.0-6.9). CONCLUSIONS: Patency of the false lumen is a strong independent prognostic factor for type B aortic dissection. Location of the most dilated aortic segment at the distal arch is a significant risk factor in the patients with a patent false lumen.

Acute Disease↗

Secondary prevention after cryptogenic cerebrovascular events in patients with patent foramen ovale.

BACKGROUND: Patients with patent foramen ovale and cryptogenic stroke are at risk of recurrence, but there are few data on strategies to prevent this. METHODS: We studied 280 consecutive patients with cryptogenic cerebrovascular events and a patent foramen ovale examined by multiplane transesophageal echocardiography. Patients received platelet inhibitors (n = 66) or anticoagulation (n = 47) or underwent device closure (n = 167). During the mean follow-up of 2.6 years, we compared the frequency of recurrent events, death and severe treatment complications. RESULTS: A total of 33 (12%) patients had a recurrent cerebrovascular event. The annual recurrence rates were 13% in patients treated with platelet inhibitors, 5.6% in those on oral anticoagulation, and 0.6% in those after device closure. Independent predictors of recurrent cerebrovascular events were a patent foramen ovale larger than 4 mm (hazard ratio 3.8, 95% CI 1.2-11.2; p = 0.017) or previous strokes (hazard ratio 4.3, 95% CI 2.0-9.2; p < 0.001). Interventional closure of the patent foramen ovale decreased the risk of a recurrent event compared with oral anticoagulation (hazard ratio 0.06, 95% CI 0.12-0.29; p < 0.001), whereas antiplatelet therapy showed a trend to an increased risk (hazard ratio 2.3; 95% CI 0.9-5.5; p = 0.055). Major side effects occurred in 7 anticoagulated patients and in 13 patients after device closure. There were two non-vascular deaths and one fatal hemorrhagic stroke. CONCLUSIONS: Patients with a large patent foramen ovale and a cryptogenic cerebrovascular event had a substantial risk of recurrence even with medical treatment. Risk of recurrence was lower after device closure of the patent foramen ovale.

Adult↗

The association between the diameter of a patent foramen ovale and the risk of embolic cerebrovascular events.

PURPOSE: We sought to determine whether the size of a patent foramen ovale affected the risk of embolic cerebrovascular events of unknown origin. PATIENTS AND METHODS: We ascertained the presence and measured the size of patent foramen ovale using multiplane transesophageal echocardiography in 121 consecutive patients younger than 60 years who had transient ischemic attacks or ischemic strokes and in 123 control subjects. None of the patients had left heart, aortic, or carotid sources of embolism, or echocardiographic signs of elevated left or right atrial pressure. We used multivariate logistic regression to determine whether the size of the patent foramen ovale was an independent risk factor for cerebrovascular events. RESULTS: The mean (+/- SD) diameter of a patent foramen ovale was significantly larger in patients (4 +/- 2 mm) than in control subjects (2 +/- 1 mm, P <0.0001). A patent foramen ovale greater than 4 mm was associated with an increased risk of transient ischemic attacks [odds ratio (OR) = 3.4; 95% confidence interval (CI), 1.0 to 11, P = 0.04], ischemic strokes (OR = 12; 95% CI, 3.3 to 44, P = 0.0001), and, especially, having evidence of two or more strokes (OR = 27; 95% CI, 4.7 to 160, P = 0.0002). CONCLUSION: The diameter of a patent foramen ovale is an independent risk factor for ischemic events, especially recurrent strokes.

Adult↗

Flow dynamics of angiographically no-flow patent internal mammary artery grafts.

OBJECTIVES: This study sought to assess the flow dynamics of internal mammary artery grafts (IMAGs) in no-flow situations by use of a Doppler guide wire. BACKGROUND: Functionally no-flow and anatomically patent IMAGs have been reported by angiography in patients with a patent recipient coronary artery. METHODS: The study included 12 patients with an IMAG to the left anterior descending coronary artery (LAD) in whom no-flow patency of the graft was suspected angiographically. Thirteen patients with a normally functioning IMAG whose LAD was occluded in the proximal portion and was supplied only from the graft served as control patients. Phasic flow velocities were recorded in the distal portion of the graft and the recipient LAD using a 0.014-in., 15-MHz Doppler guide wire at rest and during hyperemia (0.14-mg/kg body weight per min intravenous adenosine infusion). RESULTS: There were no significant differences in systolic (15+/-3 vs. 19+/-6 cm/s, p = NS), diastolic (35+/-11 vs. 37+/-7 cm/s, p = NS) and time-averaged peak velocities at rest (20+/-5 vs. 21+/-5 cm/s, p = NS), during hyperemia (51+/-12 vs. 54+/-8 cm/s, p = NS) and in coronary flow velocity reserve (2.8+/-0.9 vs. 2.7+/-0.3, NS) in the native LAD in patients with a no-flow patent graft versus control patients. Within the graft, to and fro signals with systolic reversal and diastolic anterograde flow were seen in the no-flow patent grafts, although anterograde flow signals were recorded in systole and diastole in control patients. Systolic (-28+/-19 vs. 22+/-9 cm/s, p < 0.01), diastolic (18+/-17 vs. 44+/-14 cm/s, p < 0.01) and time-averaged (-2+/-6 vs. 26+/-9 cm/s, p < 0.01) peak velocities at rest were significantly smaller in the no-flow patent grafts than in control grafts. During hyperemia, anterograde flow became predominant, with a reduction in retrograde systolic flow signal and an increase in diastolic flow velocity and time-averaged peak velocity in the no-flow patent grafts, and no-flow situations disappeared temporarily. CONCLUSIONS: Functionally no-flow situations of IMAGs manifesting to and fro signals with systolic flow reversal and diastolic antegrade low flow velocity are temporary conditions in certain hemodynamic circumstances, and these grafts function as conduits during hyperemic states.

Adolescent↗

Limb loss with patent infra-inguinal bypasses.

To determine systemic and local risk factors that contribute to limb loss despite a patent infra-inguinal bypass graft and how to prevent it, we reviewed 987 patients who underwent infra-inguinal bypasses at our institution. Seventy-five (7.6%) patent grafts failed to achieve a healed foot despite exhaustive attempts to do so and these patients underwent major amputation either above the knee (AKA) or below the knee (BKA). In 525 femoro-popliteal bypasses, there were 38 major amputations (29 BKA; 9 AKA) with a patent graft; in 462 femoro-distal bypasses, there were 37 amputations (22 BKA; 15 AKA) with a patent graft. The remaining 912 patients with limb salvage as well as all the patients with limb loss were evaluated with regard to systemic risk factors, quality of the run-off from the popliteal artery, continuity of the tibial artery into the arch as demonstrated on arteriography, the haemodynamic improvement obtained postoperatively, and the presence and extent of necrosis in the foot. The presence of diabetes, extensive pedal necrosis and advanced infection predispose to limb loss despite a patent lower extremity bypass graft. Patients who lost their limbs despite a functioning bypass to an isolated popliteal segment had significantly less pronounced haemodynamic improvement postoperatively. An early graft extension to a reconstituted tibial or peroneal artery or a direct bypass to a distal tibial or peroneal artery may reduce the incidence of limb loss in this setting. When a patent bypass to an isolated tibial or peroneal artery segment failed to relieve foot ischaemia, limb salvage was achieved by a distal extension to plantar arteries.

Amputation, Surgical↗

Atrial septal aneurysm and patent foramen ovale as risk factors for cryptogenic stroke in patients less than 55 years of age. A study using transesophageal echocardiography.

BACKGROUND AND PURPOSE: An association between atrial septal aneurysm and embolic events has been suggested. Atrial septal aneurysm has been shown to be associated with patent foramen ovale and, in some reports, with mitral valve prolapse. These two latter cardiac disorders have been identified as potential risk factors for ischemic stroke. The aim of this prospective study was to assess the role of atrial septal aneurysm as an independent risk factor for stroke, especially for cryptogenic stroke. METHODS: We studied the prevalence of atrial septal aneurysm, patent foramen ovale, and mitral valve prolapse in 100 consecutive patients < 55 years of age with ischemic stroke who underwent extensive etiological investigations. We compared these results with those in a control group of 50 consecutive patients. The diagnosis of atrial septal aneurysm and patent foramen ovale relied on transesophageal echocardiography with a contrast study and that of mitral valve prolapse, on two-dimensional transthoracic echocardiography. RESULTS: Stepwise logistic regression analysis showed that atrial septal aneurysm (odds ratio, 4.3; 95% confidence interval, 1.3 to 14.6; P = .01) and patent foramen ovale (odds ratio, 3.9; 95% confidence interval, 1.5 to 10; P = .003) but not mitral valve prolapse were significantly associated with the diagnosis of cryptogenic stroke. The stroke odds of a patient with both atrial septal aneurysm and patent foramen ovale were 33.3 times (95% confidence interval, 4.1 to 270) the stroke odds of a patient with neither of these cardiac disorders. For a patient with atrial septal aneurysm of > 10-mm excursion, the stroke odds were approximately 8 times the stroke odds of a patient with atrial septal aneurysm of < 10 mm. CONCLUSIONS: This study shows that atrial septal aneurysm and patent foramen ovale are both significantly associated with cryptogenic stroke and that their association has a marked synergistic effect. Atrial septal aneurysms of > 10-mm excursion are associated with a higher risk of stroke.

Adolescent↗

Testicular damage after exposure to carbendazim depends on the number of patent efferent ductules.

To study how long-term testicular damage depends on the patency of the efferent ductules (EFDs), rat testes and epididymides were examined after a single exposure to carbendazim (methyl 2-benzimidazole carbamate; MBC). The number of patent EFDs was determined in sections of the caput epididymides at 8, 16, 32 and 70 days post-treatment, and the testes were grouped into the following categories: those with intact EFDs, those with partially patent EFDs, or those with totally occluded EFDs. In each testis, 100 seminiferous tubules were examined for the presence of abnormalities. The mean weight of testes with partially patent EFDs was significantly higher compared with the control, whereas that of testes with totally occluded EFDs was significantly lower. Histologically, most seminiferous tubules of the testes with intact EFDs were normal. The testes with partially patent EFDs contained normal, degenerative and atrophic seminiferous tubules at various frequencies depending on the number of patent EFDs, and it was evident that as the number of patent EFDs increased, the number of normal seminiferous tubules also increased at any interval. In these testes, the number of normal seminiferous tubules increased progressively as the post-treatment interval increased, irrespective of patency of the EFDs. In the testes with totally occluded EFDs, atrophic seminiferous tubules were the most numerous. These results indicate that whether or not the testis is able to survive the long-term deleterious effects of MBC depends largely EFD patency.

Animals↗

[Reoperative coronary artery bypass grafting in patients with patent internal thoracic artery grafts].

The incidence of reoperative coronary artery bypass grafting (reCABG) is recently increasing. However, there has been no report of reCABG in patients with patent internal thoracic artery (ITA) grafts in Japan. We performed reCABG in three such patients with patent ITA grafts. The first patient was a 49-year-old male who had undergone a 2 CABG (left ITA-LAD, SVG-DX 1), 8 years and 7 months prior to the 2nd operation, he received a re 2 CABG (GEA-RCA, RITA-SVG-DX 1) with a patent prior LITA-LAD graft. The second patient was a 65-year-old female who had undergone CABG in which the LITA had been erroneously anastomosed to the DX 2 in place of the LAD. Three year later, the reCABG (RITA-LAD) was performed with a patent prior LITA-DX 2 graft. The third patient was a 51-year-old male who had undergone 3-CABG (RITA-LAD, LITA-DX, SVG-RCA). The RITA was closed most probably due to technical errors and his angina recurred. Tree year after the first operation, he received a re 3-CABG (GEA-LAD, SVG-RCA, SVG-OM) with a patent prior LITA-DX graft. In each patient, PTCA had been tried twice, twice and once prior to redo operations. Their post-redo courses were uneventful, and they were discharged free from angina. In such cases it is important to manage with care the patent ITA grafts at reoperation. Biplane ITA angiograms are quite helpful to evaluate the course of grafts in relation to the sternum. To cover the ITA graft with a GORE-TEX membrane may also be useful for easy identification of the graft at redo operations.

Aged↗

Common carotid artery occlusion with patent internal and external carotid arteries: diagnosis and surgical management.

PURPOSE: Occlusion of the common carotid artery (CCA) is generally associated with occlusion of the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA). Occasionally, however, collateral circulation to the ECA may preserve patency of the ICA via retrograde perfusion through the bulb. These patients may suffer ongoing transient ischemic attacks and risk for stroke. Recognition of this pathologic variant may allow for effective surgical intervention. METHODS: We have performed seven operations in six patients with occluded CCAs and patent ECA and ICAs. The occluded CCA was on the left side in each case (p < 0.01). Six of the operations were performed for ischemic symptoms, including amaurosis fugax in five patients, hemispheric TIA in one patient, and profound global ischemia in two patients who had concomitant occlusions of other extracranial vessels. In the five most recent cases the patent ECA and ICA above the occluded CCA were recognized by preoperative duplex scanning, which prompted cerebral angiography. A variety of reconstructive procedures were used, depending on the pathologic anatomy. These procedures included subclavian or axillary artery to carotid artery bypass with carotid endarterectomy (five), carotid endarterectomy with thrombectomy of the proximal CCA (one), and ascending aorta to carotid artery bypass (one). RESULTS: There were no strokes associated with the surgery, although one patient had transient neurologic symptoms and a seizure associated with documented reperfusion edema. Three of the patients had preoperative and postoperative transcranial Doppler studies that documented significant improvement in intracranial hemodynamics. Five of the patients have had continuously patent grafts with relief of symptoms for an average of 40 months (range 3 to 155 months). The remaining patient had graft occlusion after 72 months and underwent repeat operation for amaurosis fugax and global ischemia. His second graft remains patent, and he is symptom free 21 months later. CONCLUSIONS: Recognition of patent distal vessels above a CCA occlusion depends on a high index of suspicion, careful investigation of the carotid bulb with duplex scanning, and delayed arteriographic views of the bulb allowing for late collateral vessel filling. The favorable results in this small series of patients supports an aggressive surgical approach when patients with symptoms are encountered with patent distal vessels above an occluded CCA.

Aged↗