Photobiomodulation for Blood Pressure and Heart Rate Reduction in Mastectomized Women on Hormone Blockers: A Randomized Controlled Trial

Objective: To assess the impact of intravascular laser irradiation of blood (ILIB) on the primitive carotid artery (PCA) hemodynamic variables, specifically blood pressure (BP) and heart rate (HR), in mastectomized patients undergoing hormone blocker treatments. Materials and methods: This study is a controlled, experimental, and randomized clinical trial. Patients were allocated into two groups: the experimental group (G1)-patients who received ILIB therapy using a 660 nm laser targeted at the PCA, and the control group (G2)-patients who did not receive ILIB therapy. Clinical research was conducted weekly, with measurements of systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR. The Mann-Whitney U test for independent samples was used, with a significance level of α = 0.05. Results: Systemic photobiomodulation on the PCA did not demonstrate a statistically significant difference in relation to SBP and DBP. However, for HR, the p-value was <0.05, indicating a significant difference between G1 and G2. The initial mean p > decreased from 142.3 to 116.4 mmHg in G1, and from 130.4 to 119.8 mmHg in G2. The DBP varied from 78.8 to 72.8 mmHg in G1, and from 79.1 to 74.2 mmHg in G2. A statistically significant difference was observed in HR, decreasing from 81.3 to 62.06 bpm in G1, and changing minimally from 74.1 to 75.1 bpm in G2. A considerable reduction was present in the timing of application. Conclusions: ILIB therapy applied to the PCA induces a reduction in BP and, more notably, HR in mastectomized women using the tamoxifen or aromatase inhibitors.

Differential Phagocytosis-Based Photothermal Ablation of Inflammatory Macrophages in Atherosclerotic Disease

Inflammatory macrophage (Mφ)-mediated atherosclerosis is a leading cause of mortality and morbidity worldwide. Photothermal therapy (PTT) has been demonstrated as an efficient strategy in killing target cells, and its application in the treatment of inflammation in atherosclerosis is developing. However, the choice of nanomaterials, mechanisms, and side effects are seldom considered. In this study, semiconductor nanomaterials, that is, MoO₂ nanoclusters, were synthesized and used for the first time in PTT for inflammatory Mφ-mediated atherosclerosis. Based on cell differential phagocytosis, the optimum amount of MoO₂ and treatment time were selected to exert the maximum ablation effect on Mφ and minimal damage on endothelial cells without requiring additional target or selective groups. Moreover, MoO₂-based PTT shows an excellent therapeutic effect on atherosclerosis by eliminating Mφ in animal models, with no significant side effects observed. This study explores a new method of nanotechnology and pharmaceutical development by using and optimizing cost-effective metal oxide nanostructures in the treatment of atherosclerosis and motivates further research on minimizing the side effects of related materials.

Carotid stenosis prevalence after radiotherapy in nasopharyngeal carcinoma: A meta-analysis

PURPOSE

Radiotherapy (RT) is the most effective treatment for nasopharyngeal carcinoma (NPC) but may cause stenosis of the carotid arteries. This meta-analysis evaluates the prevalence of carotid stenosis after radiation therapy.

MATERIALS AND METHODS

Online search for studies reporting carotid stenosis in patients with NPC who received radiation therapy (RT) compared to NPC patients who did not receive RT and compared to healthy controls.

RESULTS

Twelve studies were included for a total analysis of 1928 patients (837 received RT and 1091 were controls). RT patients showed a statistically significant higher incidence of overall stenosis (pooled risk ratio = 4.17 [2.44, 7.10], p < 0.00001) and an even greater incidence of significant stenosis (50% or more) (pooled risk ratio = 8.72 [3.53, 21.55], p < 0.00001). Analyzing by individual blood vessels showed that the RT patients had significantly higher incidence of stenosis in common carotid artery (CCA), external carotid artery (ECA), carotid bulb, CCA and internal carotid artery (ICA), and CCA/ICA/carotid bulb.

CONCLUSIONS

NPC patients who receive RT have increased risk of developing carotid stenosis, and should be screened after treatment.

Do traditional risk stratification models for cerebrovascular events apply in irradiated head and neck cancer patients?

BACKGROUND

Primary radical radiotherapy (RT) for head and neck cancer (HNC) often results in significant radiation dose to the carotid arteries.

AIM

We assessed whether HNC patients are at increased risk of a cerebrovascular event primarily due to RT or other risk factors for atherosclerosis by (i) risk-stratifying patients according to validated QRISK-2 and QSTROKE scores and (ii) comparing the prevalence of carotid artery stenosis (CAS) in irradiated and unirradiated carotid arteries.

DESIGN

HNC patients treated with an RT dose >50 Gy to one side of the neck ≥2 years previously were included.

METHODS

QRISK-2 (2014) and Q-STROKE (2014) scores were calculated. We compared the prevalence of CAS in segments of the common carotid artery on the irradiated and unirradiated sides of the neck.

RESULTS

Fifty patients (median age of 58 years (interquartile range (IQR) 50-62)) were included. The median QRISK-2 score was 10% (IQR 4.4-15%) and the median QSTROKE score was 3.4% (IQR 1.4-5.3%). For both scores, no patient was classified as high risk. Thirty-eight patients (76%) had CAS in one or both arteries. There was a significant difference in the number of irradiated arteries with stenosis (N = 37) compared with unirradiated arteries (N = 16) (P < 0.0001). There were more plaques on the irradiated artery compared with the unirradiated side - 64/87 (73.6%) versus 23/87 (26.4%), respectively (P < 0.001). 

CONCLUSIONS

Traditional vascular risk factors do not play a role in radiation-induced carotid atherosclerosis. Clinicians should be aware that traditional risk prediction models may under-estimate stroke risk in these patients.

Hemodynamics changes with acute carotid baroreceptor field stimulation are age-dependent in normotensive rats

Carotid baroreceptor stimulation can treat resistant hypertension with possible effects on the vasculature beyond the decrease in arterial pressure. This study aims to characterize age-dependency of vascular hemodynamics changes with unilateral field stimulation of carotid baroreceptors in normotensive rats to infer underlying hemodynamic mechanisms. Anesthetized Wistar-Kyoto rats divided into two groups (young: n=10, 13-33 weeks; old: n=6, 52-58 weeks) were instrumented to measure heart rate (HR) and mean arterial pressure (MAP), and flow in the abdominal aorta and renal artery. Measures of aortic and renal artery stiffness and resistance were calculated. Baroreceptor stimulation caused a consistent reduction in MAP, HR, pulse pressure and aortic pulse wave velocity. In young rats reduced MAP (77 ± 10 to 64 ± 13 mmHg, p<;0.001) was concomitant with reduced mean aortic (40 ± 15 to 32 ± 11 ml/min, p<;0.05) and renal flow (3.0 ± 1.6 2.2 ± 1.1 ml/min, p<;0.001). However, in old rats reduced MAP (76 ± 14 to 64 ± 10 mmHg, p<;0.05) occurred with a reduced aortic resistance (1.8 ± 0.9 to 1.6 ± 0.9 mmHg.min/ml, p<;0.05), renal artery resistance (17.4 ± 2.4 to 16.5 ± 2.3 mmHg.min/ml, p<;0.05) and mean renal flow (4.5 ± 1.2 to 4.0 ± 1.1 ml/min, p<;0.05). This was consistent with reduced characteristic impedance in older rats in both the aorta (0.17 ± 0.08 to 0.13 ± 0.08 mmHg.min/ml, p<;0.05) and renal artery (4.97 ± 1.16 to 3.97 ± 1.08 mmHg.min/ml, p<;0.05). Stimulation caused a leftward shift in renal impedance phase frequency spectrum in both age groups indicating changes in wave reflection from the renal bed. Findings show that the reduction in MAP due to carotid barostimulation is associated with different hemodynamic mechanisms that depend on age.

Magnetic resonance imaging of the carotid artery in long-term head and neck cancer survivors treated with radiotherapy

BACKGROUND

In head and neck cancer (HNC) patients, long-term treatment-related complications include radiotherapy (RT)-induced carotid vasculopathy and stroke. The current study investigated the magnetic resonance imaging (MRI) characteristics of the carotid wall in long-term HNC survivors treated with RT.

METHODS

MRI of the carotid arteries was performed within a prospective cohort of 42 HNC patients on average 7 years after RT. Two independent radiologists assessed maximal vessel wall thickness of common and internal carotid arteries. In case of wall thickening (≥ 2 mm) the MRI signals as well as length of the thickened segment were assessed.

RESULTS

Mean (SD) age of the 42 patients at baseline was 53 (13) years and mean (SD) follow-up time after RT was 6.8 (1.3) years. In total 62% were men and 60% had one or more cerebrovascular risk factors. Mean (SD) dose of RT on the common carotid arteries and internal carotid arteries was 57 Gy (11) and 61 Gy (10), respectively. Wall thickening was observed in 58% of irradiated versus 27% of non-irradiated common carotid arteries and 24% of irradiated versus 6% of non-irradiated internal carotid arteries (p < 0.05). Mean (SD) thickness of the irradiated and non-irradiated common carotid arteries was 2.5 (0.9) and 2 (0.7) mm (p = 0.02). Mean thickness of the irradiated and non-irradiated internal carotid arteries was 1.8 (0.8) and 1.5 mm (0.3) (n.s.). Mean length of the thickened vessel wall was 48 mm versus 36 mm in the irradiated versus non-irradiated common carotid arteries (p = 0.03) and 20 mm versus 15 mm in the irradiated versus non-irradiated internal carotid arteries (n.s.). No significant differences were observed for signal intensities of the vessel walls.

CONCLUSIONS

Our study showed significantly more vessel wall thickening in irradiated versus non-irradiated carotid arteries years after RT for HNC, while no differences in signal intensities were observed.

Carotid dosimetry for T1 glottic cancer radiotherapy

OBJECTIVE

Radiotherapy for T1 glottic cancer is commonly delivered using a lateral parallel opposed pair of megavoltage photon fields. There is increasing reported evidence of cerebrovascular events due to radiation-induced carotid stenosis. An alternative field arrangement is to use an anterior oblique technique. This study compares the carotid dosimetry between the two techniques and reviews the evidence for the risk of radiation-induced vascular events.

METHODS

The radiotherapy plans of 10 patients with T1 glottic cancer treated with an anterior oblique technique were examined for carotid dose. Alternative plans were then created using a parallel opposed pair of fields and the dose to the carotids compared. All patients received 50 Gy in 16 fractions treating once daily, for 5 days in a week.

RESULTS

The average of the mean dose to the carotids with the anterior oblique technique was 21 Gy compared with 37 Gy using the lateral parallel opposed pair arrangement (p < 0.0001).

CONCLUSION

An anterior oblique field arrangement for the treatment of T1 glottic cancer results in a significantly lower radiation dose to the carotid arteries, which may be clinically important in terms of reducing the risk of cerebrovascular events in long-term survivors.

ADVANCES IN KNOWLEDGE

Although the anterior oblique technique for treating early glottic cancers is well described, and it is predictable that the dose received by the carotid arteries should be lower with this technique, to our knowledge this is the first study to quantify that reduction in dose with a series of patients.

[The influence of radiotherapy of head and neck cancers on carotid arteries]

INTRODUCTION

Modern radiotherapy of head and neck cancers involves high dosage of radiation per tissue volume including carotid arteries. Little is known about the mechanism of influence of radiotherapy to the large carotid arteries it may lead to inflammatory condition in the vascular wall, intima-media thickness (IMT) of the vessel and increase atherosclerosis. This work is based on current knowledge and presents the results of research which is based on ultrasound assessment of IMT and atheromatous changes in the carotid artery in a group of 61 irradiated patients with head and neck tumors.

OBJECTIVES

To assess IMT, the progression of the atheromatous changes in the carotid arteries of patients who had completed radiotherapy in comparison with a control group of non-treated patients and to determine the relation between the progression of the atheromatous changes, the radiation dosage and time after their radiotherapy.

PATIENTS AND METHOD

The ultrasound tested carotid arteries of 61 patients. The mean of the dose in the carotid area was 50.7 ± 10.6 Gy, and the time after the therapy completion was 41 ± 27 months. The results were compared with the measurement in the control group--62 people of similar age and risk of atherosclerosis. The stenosis was assessed using planimetric and hemodynamic methods and the structure of the plaque was assessed according to Gray-Weale.

RESULTS

The average size of IMT on the front wall of the common carotid artery (CCA) is significantly bigger than on the opposite wall, p = 0.0149. There was shown no statistic difference concerning the average size of IMT (assessed on the posterior wall of the arteries) between the group of patients after radiotherapy and the control group (p = 0.1877). It has been proven that the frequency of occurrence of plaque in the carotid arteries in the patients who had completed radiotherapy compared to the control group is 16.3% bigger. The dominant type of plaque in the group of patients who had completed radiotherapy are heterogeneous plaques with majority of low echoes Type 2 or high echoes Type 3. The surface of the plaque in the group of patients is mostly irregular in comparison with the control group. There is no relationship between the thickness of IMT and the size of dosage. However, when considering the age of the patients there is an increase of IMT depending on the radiation dosage. It has been proven that the increase of IMT for patients below 63 years of age is bigger than for patients over 63. In the last statistical analysis, which studied the influence of time after the termination of treatment on the IMT, it has been proven that there is a small correlation of there parameters but not significant from the statistical point of view.

CONCLUSION

The results of the research show that radiotherapy influences large carotid arteries by accelerating the IMT in the younger age group below 63 years of age. Radiation increases the frequency of plaque in carotid ateries and the creation of plaque of heterogeneous structure. Understanding the increase of IMT and the presence of hemodynamically important atherosclerosis as a significant risk factor for cerebro-vascular accident we need to consider the introduction of ultrasound scan as a routine test in the assessment of carotid arteries in patients who had completed radiotherapy to the head and neck area.

Involvement of inducible nitric oxide synthase in radiation-induced vascular endothelial damage

The use of radiation therapy has been linked to an increased risk of cardiovascular disease. To understand the mechanisms underlying radiation-induced vascular dysfunction, we employed two models. First, we examined the effect of X-ray irradiation on vasodilation in rabbit carotid arteries. Carotid arterial rings were irradiated with 8 or 16 Gy using in vivo and ex vivo methods. We measured the effect of acetylcholine-induced relaxation after phenylephrine-induced contraction on the rings. In irradiated carotid arteries, vasodilation was significantly attenuated by both irradiation methods. The relaxation response was completely blocked by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a potent inhibitor of soluble guanylate cyclase. Residual relaxation persisted after treatment with L-N(ω)-nitroarginine (L-NA), a non-specific inhibitor of nitric oxide synthase (NOS), but disappeared following the addition of aminoguanidine (AG), a selective inhibitor of inducible NOS (iNOS). The relaxation response was also affected by tetraethylammonium, an inhibitor of endothelium-derived hyperpolarizing factor activity. In the second model, we investigated the biochemical events of nitrosative stress in human umbilical-vein endothelial cells (HUVECs). We measured iNOS and nitrotyrosine expression in HUVECs exposed to a dose of 4 Gy. The expression of iNOS and nitrotyrosine was greater in irradiated HUVECs than in untreated controls. Pretreatment with AG, L-N(6)-(1-iminoethyl) lysine hydrochloride (a selective inhibitor of iNOS), and L-NA attenuated nitrosative stress. While a selective target of radiation-induced vascular endothelial damage was not definitely determined, these results suggest that NO generated from iNOS could contribute to vasorelaxation. These studies highlight a potential role of iNOS inhibitors in ameliorating radiation-induced vascular endothelial damage.

Effect of ultrasound on the permeability of vascular wall to nano-emulsion droplets

The effect of ultrasound on the permeability of blood vessels to nano-emulsion droplets was investigated using excised mouse carotid arteries as model blood vessels. Perfluorocarbon nano-droplets were formed by perfluoro-15-crown-5-ether and stabilized by poly(ethylene oxide)-co-poly(DL-lactide) block co-polymer shells. Nano-droplet fluorescence was imparted by interaction with fluorescein isothiocyanate-dextran (molecular weight = 70,000 Da). The permeability of carotid arteries to nano-droplets was studied in the presence and absence of continuous wave or pulsed therapeutic 1-MHz ultrasound. The data indicated that the application of ultrasound resulted in permeabilization of the vascular wall to nano-droplets. The effect of continuous wave ultrasound was substantially stronger than that of pulsed ultrasound of the same total energy. No effect of blood vessel pre-treatment with ultrasound was observed.

Sonographic assessment of acute changes in plaque size and echogenicity and in intima-media thickness of carotid arteries after neck radiation therapy

BACKGROUND

Ultrasonic assessment of acute changes in carotid artery walls before and after neck radiation therapy (RT).

METHODS

Fifty cancer patients scheduled for curative neck irradiation were included and underwent sonographic examination of carotid arteries, with assessment of intima-media thickness (IMT) and plaque size and echogenicity before and immediately after completion of RT.

RESULTS

IMT was linearly correlated with age and before RT (r = 0.267, p = 0.007) and increased after RT (0.68 ± 0.11 versus 0.87 ± 0.16, p < 0.001), without correlation with total RT dose and protocol. New plaques (six hypoechoic, one hyperechoic, and one calcified) were found in eight patients after RT, while 17 of the 44 plaques that were present before RT increased in size, and 8 soft and 1 dense plaques in nine patients became calcified.

CONCLUSIONS

Radiation in the acute phase not only increases the IMT but also causes new plaque formation and changes in plaque size and echogenicity.

Radiation arteritis: A contraindication to carotid stenting?

BACKGROUND

Carotid artery stenting (CAS) for high-risk anatomic lesions is accepted practice. Neck irradiation and radiotherapy-induced arteritis are common indications. The clinical outcomes of CAS for radiation arteritis have been poorly defined.

METHODS

A prospective database of patients undergoing CAS at a tertiary referral academic medical center was maintained from 1999 to 2006. Patients undergoing primary carotid artery stenting for significant atherosclerotic (ASOD) and radiotherapy (XRT)-induced occlusive disease were analyzed. Life-table analyses were performed to assess time-dependent outcomes. Cox proportional hazard analysis or Fisher's exact test was performed to identify factors associated with outcomes. Data are presented as the mean +/- SEM unless otherwise indicated.

RESULTS

During the study period, 150 patients underwent primary CAS, 75% with embolic protection. Fifty-eight percent were symptomatic. One hundred twenty-seven (85%) were treated for ASOD, and 23 (15%) had XRT. The 30-day all-cause mortality rate was 1% for ASOD and 0% for XRT (P = NS); overall survival at 3 years was equivalent. There was no significant difference in major adverse event rates as defined by the Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial between the groups. The 3-year neurologic event-free rate was 85% for ASOD and 87% for XRT (P = NS). Late asymptomatic occlusions were seen only in XRT patients. The 3-year freedom from restenosis rate was significantly worse for the XRT group, at 20%, vs 74% for the ASOD group (P < .05). Likewise, the 3-year patency rate was also worse for the XRT group, at 91%, vs 100% for ASOD by Kaplan-Meier analysis (P < .05). No factor was predictive of occlusion or stenosis by Cox proportional hazards analysis.

CONCLUSION

CAS for radiation arteritis has poor long-term anatomic outcome and can present with late asymptomatic occlusions. These findings suggest that these patients require closer postoperative surveillance and raise the question of whether CAS is appropriate for carotid occlusive lesions caused by radiation arteritis.

Carotid blowout syndrome in patients with head-and-neck cancers: reconstructive management by self-expandable stent-grafts

BACKGROUND AND PURPOSE

Some reports of reconstructive management of carotid blowout syndrome (CBS) with stent-grafts are promising, but some are unfavorable. This study sought to evaluate the hemostatic efficacy, safety, and outcome of reconstructive, endovascular stent-graft placement in patients with head-and-neck cancers in association with CBS.

METHODS

Eight patients with head-and-neck cancers with CBS were treated with self-expandable stent-grafts. We evaluated the initial hemostatic results, complications, and outcomes by assessing the clinical and imaging findings.

RESULTS

Immediate hemostasis was achieved in all patients. Initial complications included stroke in 1 patient and asymptomatic thrombosis of the carotid artery in 2 patients. Delayed complications included rebleeding, delayed carotid thrombosis, and brain abscess formation. Rebleeding was noted in 4 patients and was successfully managed with a second stent-graft and embolization in 2 of them. Delayed carotid thrombosis with follow-up after 3 months was found in 3 patients, 1 of whom had associated brain abscesses.

CONCLUSION

Although stent-grafts achieved immediate and initial hemostasis in patients with head-and-neck cancers and CBS, long-term safety, stent patency, and permanency of hemostasis appeared unfavorable. This treatment may be for temporary or emergency purposes rather than serving as a permanent measure. We suggest its applications in patients with acute CBS that precludes performance of an occlusion test, as well as when carotid occlusion poses an unusually high risk of neurologic morbidity. We also propose prophylactic antibiotic treatment and combined embolization of pathologic vascular feeders to improve outcomes.

Brain abscess formation: a delayed complication of carotid blowout syndrome treated by self-expandable stent-graft

A patient with hypopharyngeal cancer developed carotid blowout syndrome (CBS) treated by self-expandable stent-graft in the left carotid artery. CT scan for progressive right hemiparesis 4 months later showed multiple left cerebral abscesses and left carotid thrombosis. Although deployment of stent-grafts for CBS can achieve initial hemostasis in patients with head-and-neck cancer, the placement of a stent-graft in a field of necrosis and infection is associated with poor long-term outcome. We recommend the use of prophylactic antibiotics if endovascular foreign materials are placed in a contaminated field.

Supraclavicular radiation for breast cancer does not increase the 10-year risk of stroke

BACKGROUND

Modern radiation techniques, which limit the radiation dose to the heart during treatment for breast cancer, have greatly reduced the risk of radiation-induced cardiac injury. However, the risk of radiation damage to the carotid artery, which is often incidentally included in the supraclavicular radiation field for breast cancer treatment, is not routinely examined, and the technique used to treat this field has not changed significantly from early radiation trials. The purpose of the current study was to compare the incidence of hospitalization for stroke among women with breast cancer treated with supraclavicular radiation with those who received radiation therapy to the breast but not the supraclavicular fossa.

METHODS

Data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database for 5752 women who were diagnosed with American Joint Committee on Cancer (AJCC) Stage I-III nonmetastatic breast cancer between 1988 and 1997 were analyzed. Women included were age > or = 66 years, had known lymph node (LN) status, had tumors measuring < or = 5 cm, underwent breast surgery, and received adjuvant radiation therapy (with or without supraclavicular irradiation). Patients with < 5 years of follow-up were excluded because events in the first 5 years after radiation were unlikely to be radiation induced. A Cox proportional hazards model was used to compare patients with 0 positive LNs (surrogate group for no supraclavicular radiation, n = 5281) with patients with > 4 positive LNs (surrogate for supraclavicular radiation group, n = 471) for the endpoint of hospitalization for stroke. Time-to-event curves were calculated using the conditional Kaplan-Meier method.

RESULTS

The median follow-up for the 0 and 4+ LN cohorts were 92 months and 90 months, respectively (minimum of 60 months). The 10-year and 15-year actuarial freedom from hospitalization for stroke was 91% (0 LN) versus 89.5% (4+ LN) and 79% (0 LN) versus 81.6% (4+ LN), respectively (P = .28). Estrogen receptor status was balanced between the 2 cohorts. As expected, the 4+ cohort had more advanced tumors, higher stage, larger tumor size, and higher grade (P < .0001). In multivariate analysis including LN group, year of diagnosis, age, race, type of surgery, stage, tumor size, grade, estrogen receptor status, and Charlson comorbidity score, only increased age (hazard ratio [HR] for ages 70-74 years, 1.6; HR for ages 75-79 years, 2.1; and HR for age 80 + years, 2.7) and increasing comorbidity score were predictive of an increased risk of hospitalization for stroke.

CONCLUSIONS

Although patients with nonbreast malignancies treated with higher doses to the carotid arteries have been shown to have an increased risk of carotid injury, no evidence was found that radiation to the carotid delivered during supraclavicular irradiation for breast cancer increases the risk of hospitalization for stroke.

Is radiation a risk factor for atherosclerosis? An echo-color Doppler study on Hodgkin and non-Hodgkin patients

AIMS AND BACKGROUND

The aim of the present paper was to study the role of irradiation in the atherosclerotic process in patients affected by Hodgkin and non-Hodgkin lymphoma.

METHODS

We studied 84 subjects, 42 with Hodgkin or non-Hodgkin disease and 42 controls. All 42 cases had been irradiated and were comparable in terms of risk factors for atherosclerosis. All 84 subjects underwent echo-color Doppler of the arterial axis (carotids, abdominal aorta, and femoral arteries), and the intima-media thickness was measured.

RESULTS

The irradiated cases had a greater intima-media thickness in the carotid district, even after dividing them according to age and sex; males were affected more than females. The irradiated patients were at greater risk of developing cardiovascular events than the controls.

CONCLUSIONS

An echo-color Doppler of the carotid district is advisable in all patients who have been submitted to radiotherapy, and the patients with a significantly greater than normal intima-media thickness need a strict follow-up, and antioxidant or antiaggregant therapy should be considered.

[Radiation-induced lesions of carotid arteries: report of five cases]

This paper is aimed at the analysis and discussion of a personal experience with an unusual entity, the radiation-induced lesions of carotid arteries, based on 5 patients that were observed for the last twelve years. The series is composed of 4 men and woman, with an average age of 65 (between 51 to 77). Malignancies that required radiotherapy were diverse and the carotid lesions were recognized between 8 and 20 years after the irradiation (average 15) . They consisted in 3 occlusions and 5 stenosis of the internal carotid, 4 occlusions of the external carotid, and 2 stenosis of the common carotid artery. Four patients presented with symptoms of cerebrovascular insufficiency and 1 was asymptomatic. Three patients underwent 4 surgical procedures (1 bilateral) which consisted uniformly in the segmental resection of the stenosed arteries followed by its replacement with a graft, autologous or prosthetic. There was no operative mortality, nor significant morbidity. The main features of etiopathogeny, diagnosis and treatment of this entity are discussed, based on data published in literature, where a controversy between conventional surgery and endovascular management is evident. Conventional surgery is recognized as an effective method, bearing excellent and durable results. Endovascular management requires more consistent and long-lasting results, to be confirmed and assumed as a reliable alternative to the surgical treatment of this peculiar form of carotid arteries pathology.

Concomitant coronary and multiple arch vessel stenoses in patients treated with external beam radiation: pathophysiological basis and endovascular treatment

External beam radiation-induced stenoses isolated to the coronary arteries or peripheral vessels have been previously described. We report for the first time the clinical presentation of two patients with concomitant coronary artery and multiple arch vessel disease following external beam radiation of the chest. We review the pathophysiology, discuss the treatment options and describe the percutaneous treatment of coronary, carotid, subclavian, and axillary stenoses related to this rare but likely underdiagnosed disorder.

Neck irradiation, carotid injury and its consequences

Carotid stenosis is a major sequela of head and neck irradiation that has not received the attention it deserves. Its impact on the quality of life of patients can be substantial. This review discusses the incidence, pathogenesis and consequences of radiation-induced carotid stenosis following head and neck irradiation. This review is based on literature search (Medline and Pub Med) and cross-referencing. The incidence of significant carotid stenosis following head and neck irradiation range from 30% to 50%. Patients with carotid stenosis are at increased risk for stroke. Factors such as hypertension, diabetes, smoking and obesity increase the risk. Increased attention to the clinical signs of carotid stenosis and evaluation of these patients with appropriate imaging studies, together with strict implementation of management of hypertension and diabetes and, counseling on obesity and smoking have the potential to reduce the incidence of this sequela of head and neck irradiation. Those patients with severe carotid stenosis can be managed with endarterectomy or carotid artery stenting.

Prevention of intimal hyperplasia

OBJECTIVE

Endovascular brachytherapy, delivered by a variety of catheter-based devices, has proven clinically effective for the inhibition of neointimal hyperplasia (NIH) after coronary and peripheral balloon/stent angioplasty. No platform, however, has been developed to deliver low-dose radiation in concert with vascular surgical operations. The purpose of this study was to evaluate the vascular response following balloon injury to the rabbit carotid artery, with and without topical low-dose 45Ca, applied by an external vascular "wrap".

METHODS

Twelve rabbit carotid arteries were subjected to balloon injury by embolectomy catheter. The common carotid artery was then "wrapped" circumferentially with a biostable polyurethane membrane (Nanoskin Secant Medical, Perkasie, PA), without radiation (n = 6), or with radiation (n = 6) (45Ca approximately 50 microCi). The animals were sacrificed at 4 weeks for histologic assessment of the treated vessels.

RESULTS

The 45Ca wrap inhibited NIH evidenced by trends towards reduction of intimal area (0.46 +/- 0.19 control carotid vs. 0.35 +/- 0.15 (45)Ca-treated carotid arteries; P = .11), maximal intimal thickness (0.21 +/- 0.08 vs. 0.16 +/- 0.05; P = .12), average intimal thickness (0.12 +/- 0.06 vs. 0.08 +/- 0.03; P = .08), marginally significant reduction in percent area stenosis (33 +/- 15% vs. 21 +/- 9%; P = .06) and marked neointima suppression in areas immediately adjacent to 45Ca wrap remnants. Medial necrosis (P = .003), however, was observed slightly more for 45Ca-treated carotid arteries versus control arteries.

CONCLUSION

Low-dose 45Ca beta-radiation labeled onto a polyurethane membrane appears to inhibit NIH in an animal model.

Detection of radiation-accelerated atherosclerosis of the carotid artery by panoramic radiography

BACKGROUND

The authors review the pathophysiology, epidemiology, course of disease, dental findings and dental treatment of patients who developed atherosclerosis of the carotid artery after having received therapeutic radiation to the neck for squamous-cell carcinoma of the oral cavity, pharynx or larynx; salivary gland tumors; and lymphomas involving the cervical lymph nodes.

TYPE OF STUDIES REVIEWED

The authors conducted a MEDLINE search for 1997 through 2002 using the key terms "radiation therapy," "carotid artery" "atherosclerosis," "cancer" and "dentistry." The articles selected for further review included those published in English in peer-reviewed journals, with preference given to articles reporting randomized, controlled trials.

RESULTS

Recent advances in the delivery of radiation therapy to malignancies of the head and neck have resulted in the prolonged survival of increasing numbers of patients. However, the therapy has been implicated as causing atherosclerotic lesions in the cervical component of the carotid artery, which predisposes patients to an increased risk of developing stroke. Panoramic radiography can identify some of these lesions before they can cause a stroke. Radiation-induced atherosclerosis is common, with approximately 40 percent of patients developing hemodynamically significant carotid artery plaques within 10 years of having received irradiation.

CLINICAL IMPLICATIONS

Dentists treating patients who have received therapeutic radiation to the neck should examine the patients' panoramic radiographs for evidence of atheromalike calcifications, which appear 1.5 to 2.5 centimeters posterior and inferior to the angle of the mandible. Patients with evidence of such lesions should be referred to their physician for an ultrasound examination of their carotid arteries.

Carotid brachytherapy for in-stent restenosis

Carotid stenting has emerged as an alternative revascularization modality to endarterectomy for the treatment of carotid artery disease. Restenosis of a carotid stent may be occasionally seen. Our experience in intravascular radiation therapy for coronary restenosis has provided us the opportunity to explore this treatment strategy for carotid restenosis. We report our initial experience with brachytherapy for the treatment of restenosis after carotid stenting.

Effects of brachytherapy on intimal hyperplasia in arteriovenous fistulas in a porcine model

PURPOSE

The hypotheses of this investigation were that endovascular radiation would reduce intimal hyperplasia in arteriovenous fistulas (AVFs) and that this reduction would be associated with decreased expression of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF)-A, and tumor necrosis factor (TNF)-alpha.

MATERIALS AND METHODS

Bilateral end jugular vein-to-side carotid artery fistulas were constructed in pigs. At 48 hours, one AVF was randomly selected for endovascular radiation with (192) Iridium. The contralateral fistula received no radiation and served as a control. Animals in group 1 (n = 7) received 14 Gy of radiation at a depth of 2 mm and tissue was harvested at 29 days; animals in group 2 received 7 Gy of radiation at a depth of 2 mm and tissue was harvested at 29 days (n = 8); and animals in group 3 received 7 Gy of radiation at a depth of 2 mm and tissue was harvested at 56 days (n = 8). The area and maximum thickness of intimal hyperplasia were then measured blindly. Immunohistochemical results for VEGF, PDGF-A, and TNFalpha were obtained and analyzed blindly by assigning a score of 0-3, with 0 indicating no staining and 3 indicating maximum staining.

RESULTS

Irradiation with 14 Gy caused severe fibrosis in the media of the vein, with thrombosis of three of seven AVFs. Compared with the control group, the group that underwent irradiation with 7 Gy had significantly reduced intimal area at 56 days (9.9 mm(2) +/- 4.9 vs 2.1 mm(2) +/- 1.1; P =.001). This reduction correlated with significant reduction in the expression of VEGF (score of 2.2 +/- 0.1 vs 1.2 +/- 0.2; P =.001) and TNFalpha (1.3 +/- 0.1 vs 0.9 +/- 0.1; P =.04).

CONCLUSION

Fourteen grays is an excessive radiation dose for veins, causing medial fibrosis and thrombosis of the AVF. Irradiation with 7 Gy effectively inhibited the formation of intimal hyperplasia in AVF. This inhibition correlated with decreased expression of VEGF and TNFalpha.

[Recurrent hypertensive crises associated with severe orthostatic hypotension due to baroreflex failure syndrome]

The baroreflex mechanism is a central part of the regulation of the cardiovascular system, particularly in the control of vagal and sympathetic outflow to the heart and the peripheral circulation. Failure of the baroreflex is a rare cause of secondary hypertension. It is characterized by drastic changes in sympathetic activation and blood pressure following complete denervation of the baroreflex. Here, we report a case of baroreflex failure following bilateral carotid artery surgery and radiation. Moreover, postoperative orthostatic hypotension with recurrent syncope suggests a rare subform, the selective baroreflex failure, where efferent parasympathetic activity is preserved. Both high blood pressure and orthostatically induced syncope improved substantially after treatment with clonidine.

Relative risk of stroke in head and neck carcinoma patients treated with external cervical irradiation

OBJECTIVE

To determine the rate of cerebrovascular events (stroke) in patients irradiated to high doses for squamous cell carcinoma of the head and neck.

STUDY DESIGN

Retrospective chart review of 413 patients treated from 1987 to 2000 with squamous cell carcinoma of the head and neck was performed to determine the risk of stroke compared with the expected rate.

METHODS

Surgical, radiotherapeutic, radiological, and clinical or office records of 413 patients were analyzed, and data were collected regarding clinical risk factors for stroke, irradiation parameters, and follow-up on whether or not a stroke event occurred. The actuarial risk of stroke for this population was calculated and compared with expected risk from population-based data.

RESULTS

Of the 413 patients, 20 had strokes in follow-up, occurring between 2 and 146 months after radiotherapy. The 5-year actuarial rate of stroke was 12%, which corresponded to a relative risk of 2.09 ( P=.0007) compared with the population-based "expected" data. Median radiation therapy dose was 64 Gy; there was no correlation between radiation therapy dose and stroke risk. No correlation was identified between surgery near the carotids and stroke risk.

CONCLUSIONS

An association between high-dose cervical irradiation for squamous cell carcinoma of the head and neck and stroke is demonstrated. Although the relative risk is approximately doubled, the absolute risk is modest in comparison to the risk of cancer recurrence. Further study of this association and possible interventions is warranted.

Photodynamic therapy mediated induction of accelerated re-endothelialisation following injury to the arterial wall: implications for the prevention of postinterventional restenosis

OBJECTIVE

Accelerated re-endothelialisation may inhibit the development of restenosis. Basic Fibroblast Growth Factor (bFGF) plays a key role for early proliferative activity in the artery following injury. Therefore, this study was devised to examine the effect of photodynamic therapy (PDT) on post-injury re-endothelialisation in vivo, and bFGF-mRNA expression in endothelial cells (EC) in vitro.

MATERIALS AND METHODS

Rat carotid arteries were balloon-injured prior to PDT. Arteries were analysed after 1, 3, 5, 14 and 30 days. Morphometric measurements were undertaken following injection of 0.5% Evans Blue which stains non-endothelialised surfaces only. To identify EC, immunohistochemistry (CD-31) was performed. Proliferation was assessed by fluorescence cell counting. PCR quantification of bFGF-mRNA expression and proliferation were assessed in bovine aortic EC which were plated on isolated, PDT-treated EC-derived extracellular matrix at (12), 24, 48 (72 h).

RESULTS

Three days following PDT, arteries displayed significantly increased endothelial lining (p = 0.02), which was more pronounced at 5 (p = 0.03) and 14 days (p = 0.02). At 30 days no relevant differences between PDT and control were noted. EC proliferation on PDT-treated matrix was significantly increased at 24, 48, and 72 h (p = 0.0004), whereas bFGF-mRNA expression was significantly increased at 24 h only (p = 0.007).

CONCLUSION

Post-injury PDT appears to accelerate re-endothelialisation. Expression of bFGF-mRNA, however, although increased shortly after PDT, may not be responsible for a constant stimulation of EC proliferation.

Carotid artery stenting for stenosis following revascularization or cervical irradiation

PURPOSE

To assess the safety and efficacy of carotid artery stenting (CAS) for stenosis following revascularization or cervical irradiation.

METHODS

Twenty-two CAS procedures performed on 21 patients (20 men; mean age 69.3 years, range 58-87) from June 1997 to June 2000 were retrospectively reviewed. There were 5 radiation-induced carotid stenoses in 4 patients and 17 postsurgical restenoses. The mean interval between carotid revascularization and CAS was 48.1 months (range 6-264), while the elapsed time from irradiation to CAS was always >8 years (range 8-28). Seven patients screened during this period were excluded from CAS because of a duplex-defined >50% hypoechoic lesion and/or angiographic documentation of an irregular ulcerated stenosis.

RESULTS

Four Palmaz and 16 Wallstents were successfully deployed in 20 arteries; 1 access failure prompted conversion to surgery and a stent delivery failure resulted in 1 patient receiving balloon dilation only (technical success 91%). No complications were encountered in the periprocedural period, and no neurological events were observed during a mean follow-up of 16.6 months (range 3-36). One patient died at 20 months from an unrelated cause. One (4.8%) restenosis was detected after 1 year in the patient who did not receive a stent.

CONCLUSIONS

CAS is a safe alternative to conventional surgery in patients with carotid artery stenosis following surgical revascularization or cervical irradiation provided preoperative testing excludes stenoses at risk for embolism.

External beam irradiation for inhibition of intimal hyperplasia following prosthetic bypass: preliminary results

To determine whether external beam irradiation delivered immediately after graft implantation can inhibit anastomotic intimal hyperplasia (IH) 1 month following polytetrafluoroethylene (PTFE) bypass in a sheep carotid artery model, 23 sheep underwent bilateral bypass of the ligated common carotid artery with 8-mm PTFE immediately followed by a single dose of irradiation (15, 21, or 30 Gy) to one side. The 15 animals with bilaterally patent grafts were euthanized at 1 month and graft-arterial anastomoses harvested. Using computer-aided image analysis, IH areas and thicknesses were measured. Graft patency in this model was 83% at 1 month and did not differ according to treatment administered. In the control animals, IH was greatest at mid-anastomosis, but minimal within the native vessel. All three radiation doses markedly inhibited mid-anastomotic IH area and thickness. At the proximal anastomosis, 30 Gy reduced the IH area 20-fold, from 2.06 to 0.14 mm2 (p < 0.0001 by ANOVA), and IH thickness 70-fold, from 29.0 to 0.4 micron (p < 0.0002); similar effects were seen at the distal anastomosis. No adverse effects of radiation treatment were observed. External beam irradiation in doses of 15 to 30 Gy delivered in a single fraction immediately after operation markedly inhibits development of intimal hyperplasia 1 month following end-to-side anastomosis with PTFE in sheep.

External-beam radiation therapy for improved dialysis access patency: feasibility and early safety

Rectenwald, J. E., Pretus, H. A., Seeger, J. M., Huber, T. S., Mendenhall, N. P., Zlotecki, R. A., Palta, J. R., Li, Z. F., Hook, S. Y., Sarac, T. P., Welborn, M. B., Klingman, N. V., Abouhamze, Z. S. and Ozaki, C. K. External-Beam Radiation Therapy for Improved Dialysis Access Patency: Feasibility and Early Safety. Radiat. Res. 156, 53-60 (2001).Prosthetic dialysis access grafts fail secondary to neointimal hyperplasia at the venous anastomosis. We hypothesized that postoperative single-fraction external-beam radiation therapy to the venous anastomosis of hemodialysis grafts can be used safely in an effort to improve access patency. Dogs (n = 8) underwent placement of expanded polytetrafluoroethylene grafts from the right carotid artery to the left jugular vein. Five dogs received single-fraction external-beam photon irradiation (8 Gy) to the venous anastomosis after surgery. Controls were not irradiated. Shunt angiograms were completed 3 and 6 months postoperatively. Anastomoses, mid-graft, and the surrounding tissues were analyzed. Immunohistochemistry for smooth muscle cell alpha-actin, proliferating cellular nuclear antigen (PCNA), and apoptosis was performed. Incisions healed well, though all animals developed wound seromas. One control suffered graft thrombosis 4 months postoperatively. Angiography/histology confirmed severe neointimal hyperplasia at the venous anastomosis. The remaining seven dogs developed similar amounts of neointimal hyperplasia. PCNA studies showed no accelerated fibroproliferative response at irradiated anastomoses compared to controls. Skin incisions and soft tissues over irradiated anastomoses revealed no radiation-induced changes or increase in apoptosis. Thus we conclude that postoperative single-fraction external-beam irradiation of the venous anastomosis of a prosthetic arteriovenous graft that mimics the situation in humans is feasible and safe with regard to early wound healing.

One stage carotid artery resection: reconstruction in radiated head and neck carcinoma

PURPOSE

Management of the carotid artery involved with metastatic squamous cell carcinoma continues to be a topic of much discussion. Early reports, for the most part, focused on the sequel of ligation and the development of various tests to predict patient tolerance for the procedure. More recent alternatives have described resection reconstruction in multistage procedures. By using immediate reconstruction with autogenous arterial grafting, carotid artery resection can be accomplished in patients with radiation failure in a single stage. This technique can be used without the addition of myocutaneous flaps, controlled fistulas, or intracranial surgery advocated for usage with alternative techniques.

PATIENTS AND METHODS

Immediate reconstruction after resection of the carotid artery with superficial femoral arterial graft is described.

RESULTS

In a series of 18 high-risk patients with radiation failure, the artery was successfully resected and reconstructed in 1 stage without any neurologic or vascular complications. The technique has been associated with prolonged survival in selected patients.

CONCLUSION

Carotid artery resection and immediate reconstruction can be performed in high-risk radiation failure patients with acceptable complications, and is associated with prolonged survival in selected cases.

Surgery for carotid artery stenosis following neck irradiation

Carotid angioplasty and stenting (CAS) is being promoted for patients with carotid artery stenosis who have received neck irradiation. We reviewed our experience with carotid endarterectomy (CEA) following neck irradiation to determine if indeed postoperative and long-term problems were an issue in these patients. Over the past 13 years, 10 patients with a history of neck irradiation underwent 11 procedures. The average time interval between radiation treatment and surgery was 14 years (range 1-44). All carotid arteries were repaired with a standard endarterectomy, eight of which were patched. Three patients had undergone a radical neck dissection on the side ipsilateral to the carotid lesion. They received a pectoral myocutaneous flap (PMF) to protect the carotid artery and optimize wound healing. The lack of perioperative complications and of morbidity indicate that carotid reconstruction for patients with previous neck irradiation is safe and durable. Until long-term favorable results with CAS are available for these patients, operative intervention should remain the standard treatment.

A prospective study of the effects of irradiation on the carotid artery

OBJECTIVES/HYPOTHESIS

To prospectively assess the effects of irradiation on the carotid artery in patients with head and neck cancer, as a possibly relevant factor in cancer treatment planning.

STUDY DESIGN

Prospective study from a tertiary care academic setting on university (22 patients) and Veterans Affairs (14 patients) hospital patients; 1-year follow-up, including comparison of study data with age-matched and sex-matched control subjects from epidemiological studies.

METHODS

Thirty-six patients with head and neck cancer who underwent therapeutic neck irradiation were examined by high-resolution ultrasound before and 1 year after treatment. Twelve patients were also studied at 2 years. Measurements included the intima-media thickness (IMT) of the carotid artery wall, the degree of stenosis as estimated from velocity measurements, and the presence and size of plaque.

RESULTS

The pretreatment carotid IMT at baseline was 0.68 mm and was comparable to age-matched and sex-matched control subjects. Significant increase in the IMT was observed on both the left (0.67 vs. 0.84 mm) and the right (0.7 vs. 0.87 mm) sides (P < .001) 1 year after irradiation. In 12 patients who completed 24 months of follow-up the carotid IMT continued to significantly increase statistically compared with that at the first year after treatment (left side, 0.79 vs. 0.85 mm, P = .037; right side, 0.79 vs. 0.95 mm, P = .014). Statistically significant thickening of the carotid wall developed in all 36 patients by 1 year. Two patients experienced post-treatment neurological events and an area of stenosis greater than 75%.

CONCLUSIONS

Neck irradiation significantly increases the thickness of the carotid wall during the first year after treatment--on average, 21 times more than in epidemiologically matched control volunteers. This phenomenon should be taken into consideration when planning treatment for the node-negative (NO) neck.

Surgical management of atherosclerotic carotid artery stenosis after cervical radiation therapy

Carotid surgery following external cervical irradiation has not been a treatment of choice. The purpose of this retrospective study was to describe the immediate and long-term outcome in a series of 17 consecutive patients who underwent operative treatment for carotid artery stenosis after radiation therapy. From 1989 to 1997, surgical treatment of carotid artery disease was carried out in a total of 723 patients. Seventeen of these patients, 14 men and 3 women, had undergone previous external cervical irradiation; their mean age was 61.7 years. The indication for radiation therapy was ear-nose-throat cancer in 14 patients and lymphoma in 3 patients. In 10 patients, irradiation was associated with cervical surgery. The mean delay between radiation therapy and carotid artery repair was 10 years. All 17 patients were considered to be in remission at the time of carotid repair. The indication for carotid surgery was asymptomatic stenosis in 6 cases (33%) and symptomatic stenosis in 12 (67%). The procedure consisted of endarterectomy in 12 cases (67%) and venous bypass in 6 (33%). The outcome for these patients was favorable, indicating that carotid artery repair following cervical radiation therapy is safe. Results are comparable to those of procedures performed in patients with no history of cervical irradiation.

[Circulating immune complexes in acute concussion of the brain]

The aim of the study was to study the count of circulating immune complexes (CIC) in the blood of children with acute concussion of the brain. The fact that CIC at high concentrations that can penetrate into the brain through the blood-brain barrier and cause complications as vasculitis, microangiopathy, proliferative processes in the meninges, enlarged ventricles of the brain, and atrophy of its tissue was borne in mind. The studies revealed a significant progressive CIC increase within 3 weeks. For correction of blood CIC levels, laser exposure was applied to the carotid and vertebral arteries and acupuncture points. For comparison, thymaline in age-specific doses was used. Laser radiation showed a significant fall of CIC at days 19-21, particular when applied to the acupuncture points. Thymaline did not affect blood CIC levels. Laser application to the acupuncture points in children with acute brain concussion should reduce the incidence of complications of brain injury disease.

Accelerated carotid artery disease after high-dose head and neck radiotherapy: is there a role for routine carotid duplex surveillance?

PURPOSE

High-dose external radiotherapy used in the treatment of head and neck carcinoma has been implicated as a risk factor for accelerated atherosclerotic disease of the carotid arteries. However, how radiotherapy affects atherosclerotic disease is controversial, and little data exist to demonstrate a strong relationship between radiotherapy and progressive carotid disease.

METHODS

We performed a retrospective chart review of 69 patients (all men) who underwent duplex ultrasound scanning examinations for carotid disease between 1993 and 1998. Twenty-three patients had received high-dose radiotherapy for the treatment of head and neck carcinoma within the past 12 years (group 1; mean age, 67.8 years), and 46 patients were randomly selected as age-matched control subjects (group 2; mean age, 68.3 years). The mean radiation dose was 6060 +/- 182 rads, and the average interval between radiotherapy and ultrasound scanning was 6. 5 +/- 1.8 years. There was no significant difference between the two groups in the presence of these comorbidities: diabetes mellitus, coronary artery disease, hypertension, tobacco use, hypercholesterolemia, peripheral vascular disease, or stroke. Similarly, there was no difference in the indications for the duplex scanning studies.

RESULTS

Five of the 23 patients in group 1 (21. 7%) were found to have advanced carotid disease (70% to 99% stenosis); four patients were symptomatic, three patients went on to endarterectomy, and one patient was awaiting surgery. Two of the 46 patients in the control group (4%) had advanced carotid disease. One patient was symptomatic, and both patients underwent endarterectomy. A significant difference in the prevalence of advanced disease between the two groups was noted (P =.037). Sixteen patients who survived irradiation underwent a second duplex scanning study and had evidence of progressive disease with significant increases in peak systolic velocities.

CONCLUSION

High-dose radiotherapy to the head and neck region may be a significant risk factor for accelerated carotid atherosclerotic disease. Routine carotid duplex surveillance may be warranted in this high-risk patient population.

Asymptomatic carotid arterial disease in young patients following neck radiation therapy for Hodgkin lymphoma

PURPOSE

To determine the prevalence and severity of asymptomatic carotid arterial disease in young patients following neck radiation therapy for Hodgkin lymphoma and to compare the prevalence of carotid arterial disease following radiation therapy alone with that following radiation therapy and chemotherapy.

MATERIALS AND METHODS

Forty-two survivors of childhood or early adult Hodgkin lymphoma aged 18-37 years who had undergone radiation therapy more than 5 years earlier underwent carotid arterial ultrasonography. Common carotid intima-media thickness was measured; carotid vessels were assessed for intima-media abnormalities. Results were compared with those from 33 control subjects.

RESULTS

Patients had a significantly greater number of abnormal scans than did control subjects (11 [26%] vs one [3%]; P < .01). Ten patients (24%) had intima-media abnormalities that did not cause significant stenosis; one patient had diffuse bilateral intima-media thickening (mean, 1.99 mm) with greater than 70% stenosis of both common carotid arteries. Intima-media thickness was significantly greater in patients (0.51 mm) than in control subjects (0.43 mm; P < .005). The number of abnormalities in patients with radiation therapy plus chemotherapy (six [19%] of 31 patients) did not differ significantly from the number in patients with only radiation therapy (five [45%] of 11 patients; P = .12); there was no significant difference between median intima-media thicknesses (0.50 mm vs 0.51 mm, P > .2).

CONCLUSION

Asymptomatic carotid arterial disease occurs frequently in young patients following neck radiation therapy for Hodgkin lymphoma. No difference in prevalence was shown between only radiation therapy and radiation therapy plus chemotherapy.

The effect of external electron beam on neointima in rat carotid artery injury model

PURPOSE

Endovascular irradiation with either a gamma or a beta source has shown to reduce neointimal proliferation. However, the effect of external-beam radiation on neointimal hyperplasia is controversial. The objective of this study was to determine the effect of external-beam irradiation with different doses on neointimal hyperplasia in the rat carotid artery injury model.

METHODS AND MATERIALS

Twenty-seven Sprague-Dawley rats underwent endothelial denudation injury by 2F Fogarty balloons on carotid artery. Immediately after the injury, rats were irradiated externally using 6-MeV electrons. Rats were grouped according to the radiation doses, 0 Gy as controls (n = 5), 5 Gy (n = 5), 10 Gy (n = 5), 15 Gy (n = 6), and 20 Gy (n = 6). Then, rats were sacrificed after 2 weeks and the carotid arteries were perfusion-fixed in paraformaldehyde. External elastic lamina (EEL) area, lumen area, maximal intimal thickness (MIT), and intimal area (IA) of the injured segments were measured on the basis of histomorphometry.

RESULTS

In EEL and lumen area, there was no statistically significant difference between the irradiated groups and the controls. In MIT and IA, low-dose radiation (5 Gy and 10 Gy) did not induce any significant reduction. High-dose radiation (15 Gy and 20 Gy), however, reduced MIT and IA significantly.

CONCLUSION

External electron beam reduced the intimal area, and the inhibition of neointimal proliferation was dependent upon radiation doses. This study suggests that the minimal effective dose for the inhibition of neointimal hyperplasia following denudation injury in the rat carotid model is between 10 Gy and 15 Gy.

Carotid artery repair for radiation-associated atherosclerosis is a safe and durable procedure

OBJECTIVE

The development of carotid atherosclerosis after neck irradiation is well documented. There has been concern about the safety and durability of carotid artery repair through a radiated field. The objective of this report is to describe the immediate and long-term results of a series of cases collected in a 13-year interval.

METHODS

From 1984 to 1997, 24 patients underwent 26 carotid artery operations. All the patients had undergone prior radiation therapy at a mean interval of 17 years, with an average radiation dose of 6300 rad. Severe scarring of the skin or radiation fibrosis were present in two thirds of the patients, with 4 patients having permanent tracheostomies. The indications for carotid surgery included cerebral or monocular transient ischemic attack (58%), asymptomatic high-grade stenosis (27%), prior stroke (12%), and tumor invasion of the carotid artery (4%). General anesthesia was used with selective shunting on the basis of carotid artery back pressure or electroencephalography monitoring. Patch angioplasty closure was used in 79% of the patients. The operations included standard carotid endarterectomy (n = 20), external carotid endarterectomy (n = 2), carotid patch angioplasty alone (n = 2), aortocarotid bypass grafting (n = 1), and carotid interposition grafting (n = 1). Four patients required skin grafting or myocutaneous flaps.

RESULTS

No deaths or strokes occurred within 30 days of the operations. Six patients had transient cranial nerve palsy, and two had wound infections. The patients were followed from 1 to 156 months, with six patients being followed for longer than 18 months. No strokes were seen at late follow-up examination. Duplex scan examination documented one occlusion, in a patient with primary closure, and two restenoses, one of which necessitated reoperation. The remainder of the grafts were widely patent.

CONCLUSIONS

Carotid surgery after neck irradiation is safe and durable. The long-term patency rates and the protection against subsequent neurologic events are similar to the results obtained in the absence of radiation therapy. Problems of wound healing were not found in this series.

Cellular and molecular mechanisms of radiation inhibition of restenosis. Part I: role of the macrophage and platelet-derived growth factor

PURPOSE

The major radiobiological issue in determining the rationale for the use of radiation to inhibit vascular restenosis is the identification of the target cell(s) and/or cytokine(s) responsible for neointimal hyperplasia and vascular remodeling. The central hypothesis of this report is that the macrophage/monocyte and PDGF are key elements in the process of neointimal hyperplasia seen following angioplasty, similar to their role in lesion formation and progression found in atherosclerotic thickening. Specific immunohistochemical and cytochemical stains were applied to a rat carotid model in a temporal series after balloon angioplasty to determine macrophage activity vs. smooth muscle cell proliferation, the latter being classically thought to be the cell responsible for restenosis.

METHODS AND MATERIALS

Neointimal hyperplasia was created in an established rat carotid artery model by a balloon catheter technique. Immediately following injury, treatment groups received irradiation via high dose rate (HDR) brachytherapy, the 192Ir source being placed externally to the vessel. Radiation was delivered to a length of 2 cm of the injured vessel at doses of 5, 10, and 15 Gy, and the animals were sacrificed at various time points following treatment (24 h to 6 months). Serial sections of tissue were stained immunohistochemically with the primary antibodies CD11b, mac-1, anti-PDGF, and alpha-smooth muscle actin.

RESULTS

Immediately (24 h) postinjury, there is an apparent migration of macrophages seen in the adventitia; after 1 week, proliferation and migration of macrophages could be seen clearly within all the vessel layers, especially in the intima; by 3 weeks, when there was evidence of neointimal hyperplasia, macrophages could still be seen, mainly in the intima scattered among the smooth muscle cells and myofibroblasts, and to a lesser degree at 6 months. There was corresponding expression of PDGF, whenever and wherever there were zones of activation/neointimal hyperplasia. Alpha-smooth muscle actin staining identified the smooth muscle cells distinct from the macrophages, and these SMCs exhibited activation in the neointimal hyperplasia zones at all later time points. Furthermore, we showed that radiation significantly reduced the macrophage population, while the onset of neointimal hyperplasia was accompanied by a return of the macrophage population.

CONCLUSION

Our results suggest that the activated adventitial macrophage/monocyte are the key cells responsible for initiating the arterial neointimal hyperplasia and vascular remodeling developing postangioplasty as they are in the initiation and perpetuation of atheromatous thickening. Irradiation delivered immediately postinjury is, therefore, highly effective, because the macrophage population is exquisitely radiosensitive.

Feasibility and safety of beta irradiation in human coronary arteries

We have developed a technique of endoluminally centred endovascular beta irradiation aimed at preventing restenosis after PTCA. The source consists of a pure metallic 90-Yttrium coil that can be positioned within the lumen at the target site by the use of a centering device and an afterloading console. Experimental evaluation of this approach showed that a dose of 18 Gy delivered at the inner arterial surface was highly effective in preventing fibrointimal hyperplasia in rabbit carotid and iliac arteries. A pilot clinical evaluation in the coronary arteries of 15 patients using the same dose demonstrated excellent feasibility and no unexpected side-effects. A dose-finding evaluation in the clinical setting is now planned.

Progressive cerebral occlusive disease after hypothalamic astrocytoma radiation therapy

An 18 year-old woman received radiation therapy for hypothalamic astrocytoma at the age of 11 years. She developed progressive cerebral occlusive vascular disease with moyamoya vessels formation in both carotid systems. Apart from diabetes mellitus, she had no other risk factors for occlusive cerebrovascular disease. The site of occlusion was confined to the field of radiation and the development of moyamoya vessels strongly suggestive of a radiation-induced cause. Radiation therapy around the sella and parasellar region appears to be the most common risk factor for this vasculopathy. Progressive irradiation-induced cerebral vasculopathy is due to accelerated atherosclerosis.

Interstitial iodine 125 in advanced recurrent squamous cell carcinoma of the head and neck with follow-up evaluation of carotid artery by ultrasound

We retrospectively reviewed our experience with 24 patients in the treatment of advanced recurrent squamous cell carcinoma of the head and neck, using salvage surgery and intraoperative iodine 125 (125I) implantation. Surgical complications and survival results were compiled and compared with those of other studies. The long-term effect of 125I on the carotid artery was evaluated by ultrasound. We had a major complication rate of 21% and an overall complication rate of 50%. Our 2-year overall and determinate survivals were 29% and 50%, respectively. Within the survival group, carotid ultrasounds were obtained to evaluate the long-term effect of 125I. All ultrasounds obtained at least 1 year from the time of treatment showed minimal or no change from the contralateral side. We conclude that intraoperative 125I and salvage surgery are an acceptable treatment for recurrent squamous cell carcinoma with minimal complication and effect on the carotid artery.

Inhibition of intimal hyperplasia in balloon injured arteries with adjunctive phthalocyanine sensitised photodynamic therapy

OBJECTIVES

We investigated the effects of Photodynamic therapy (PDT) using Aluminium disulphonated phthalocyanine (AlS2Pc) on experimental intimal hyperplasia (FCIH).

MATERIALS AND METHODS

(a) Pharmacokinetics: Normal rats were injected with Als2Pc and carotid artery fluorescence was measured. (b) Normal artery PDT: Sensitised rats underwent carotid artery laser irradiation (50J/cm2, 675nm) and were assessed after 3 and 14 days and 1-6 months. (c) PDT: Rats underwent standard carotid artery balloon injury immediately prior to PDT and arteries were assessed at 2 to 26 weeks, together with laser, AlS2Pc, and untreated controls.

CHIEF OUTCOME MEASURES

(a) Fluorescence intensity in different arterial layers. (b) Medial smooth muscle cell counts per high power field (light microscopic). (c) Percentage amount of FCIH (area of intimal hyperplasia) as a ratio of the IEL (area enclosed by the internal elastic lamina).

RESULTS

(a) AlS2Pc fluorescence intensity increased with increasing dosage, with maximal fluorescence in the arterial media at 30 min. (b) PDT produced medial cell depletion at 3 days and persisted over 6 months without loss of vessel integrity. (c) PDT completely inhibited FCIH at 2 and 4 weeks. This was partial at 6 to 26 weeks (51% of untreated level). PDT inhibition of FCIH was significantly greater than in any of the control groups. p < 0.0001. Mann-Whitney Test.

CONCLUSION

Adjunctive AlS2Pc sensitised photodynamic therapy inhibits experimental intimal hyperplasia, by causing medial smooth muscle cell depletion. This offers a new approach to the management of angioplasty restenosis in patients.

Acute confusion in a young man

Images

Intra-arterial beta irradiation prevents neointimal hyperplasia in a hypercholesterolemic rabbit restenosis model

BACKGROUND

Intra-arterial gamma irradiation has been shown to reduce restenosis after balloon angioplasty. The use of beta emitters should allow similar effects while inducing less undue tissue irradiation radioprotection problems.

METHODS AND RESULTS

Flexible 90-yttrium (90Y) coils inside a centering balloon were used to allow homogeneous intraarterial dose delivery. One carotid and one iliac artery of 21 hypercholesterolemic rabbits were deendothelialized and then irradiated. Four dose schedules were studied: (1) control (dilated, nonirradiated); (2) 6 Gy; (3) 12 Gy; and (4) 18 Gy. Arterial specimens were histologically evaluated at 8 days and at 6 weeks. For all radiation doses at 8 days compared with controls, there was a significant decrease in bromodeoxyuridine-labeled cells (245 +/- 93 cells/cm in control, 42 +/- 27 in 6 Gy, 72 +/- 107 in 12 Gy, and 2 +/- 2 in 18 Gy groups; P < .001) and in total neointimal cells (891 +/- 415 cells/cm in control, 79 +/- 43 in 6 Gy, 192 +/- 264 in 12 Gy and 22 +/- 13 in 18 Gy groups; P < .0002). At 6 weeks, computer-derived histological percent area stenosis was reduced from 26 +/- 10% in the control group to 1 +/- 1.3% in the 18 Gy group (P < .0001), but lower doses had no significant effect.

CONCLUSIONS

Administration of intra-arterial beta irradiation with a 90Y source is technically feasible and compatible with an ordinary catheterization laboratory environment. A dose of 18 Gy effectively induces long-term inhibition of neointimal hyperplasia.

The effect of photodynamic therapy on the mechanical integrity of normal rabbit carotid arteries

Photodynamic therapy (PDT) for tumor ablation is effective in the treatment of superficial cancers. Adjunctive intraoperative PDT has been proposed for the "sterilization" of tumor beds after the resection of malignancies. Arteries in photosensitized animal models exposed to appropriate light receive characteristic injury. This study was conducted to determine whether photodynamic injury to the rabbit carotid artery results in thrombotic occlusion or weakening of the vessel wall. PDT of the carotid arteries of New Zealand white rabbits, using either disulphonated aluminum phthalocyanine or 5-aminolevulinic-acid-induced protoporphyrin IX as the photosensitizer, was performed with a light dose of 100 J/cm2. Histologic examination of the carotids treated with either agent demonstrated typical full-thickness loss of cellularity 3 days after PDT. All vessels remained patent, and no inflammatory infiltrate was evident. Elastin van Gieson staining showed preservation of inner and medial elastic laminae and medial and adventitial collagen. Additional rabbits were similarly treated with PDT to 1-cm segments of both common carotid arteries. The animals were sacrificed at 3, 7, and 21 days. The carotids were exposed, and both control and treated segments were subjected to intraluminal hydrostatic distention until the vessels burst. No reduction in the pressure required to burst the vessels was evident in the treated vessels as compared with the control vessels. The authors of the study concluded that despite full-thickness cell death, PDT-treated arteries are not at risk for thrombotic occlusion or hemorrhage.