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Biomedical subjects

David F Kallmes

Publications and source records attributed to David F Kallmes.

At least 37 records · Page 2Linked to original sources
PubMed2005

Vertebroplasty in the inpatient population.

BACKGROUND AND PURPOSE: Vertebroplasty is frequently offered to patients hospitalized for refractory pain due to vertebral fractures, because it is assumed that the procedure will facilitate resolution of pain and a rapid hospital discharge. We report our experience with inpatient vertebroplasty, with attention to rapidity of discharge and relevant clinical parameters. METHODS: We retrospectively reviewed the duration of hospitalization in patients admitted with primary diagnoses of back pain or vertebral fracture who were treated with vertebroplasty. We cataloged outcomes in the form of verbal pain scales (graded 0-10), in-hospital medication use (graded 0-6), and posthospitalization medication use. Outcomes were assessed at baseline and at 1 week, 1 month, 6 months, 1 year, and 2 years postvertebroplasty. RESULTS: We identified 66 such patients who had a median total hospital stay of 6.0 days (range, 1-26 days). Median length of stay before and after vertebroplasty were 4.0 (range, 1-24 days) and 1.5 days (range, 0-7 days), respectively. Ten (15%) patients were discharged the day of vertebroplasty. By days 2 and 3, 33 (50%) and 48 (72.7%) of the 66 patients had been discharged. Patients who received vertebroplasty earlier in the course of hospitalization demonstrated greater decreases in medication strength by discharge (P = .045). There was significant improvement in all outcome measures by 1 week, with continued improvement at 1 and 6 months. CONCLUSION: This study confirms that vertebroplasty facilitates a rapid hospital discharge as well as long-term improvement in patients admitted for refractory pain. Vertebroplasty administered earlier in hospitalization also leads to greater decreases in analgesic requirements.

Aged↗
PubMed2005

Angiographic and histologic analysis of experimental aneurysms embolized with platinum coils, Matrix, and HydroCoil.

BACKGROUND AND PURPOSE: A report directly comparing platinum coils, Matrix coils, and HydroCoils in a single animal model does not currently exist. We evaluated and compared the performance of these three products in the embolization of experimental aneurysms. METHODS: Thirty-three elastase-induced saccular aneurysms were created in rabbits. Aneurysms were embolized with Matrix coils (n = 15), HydroCoils (n = 9), or platinum coils (n = 9). The groups were compared with respect to the following parameters: aneurysm size, procedure duration, number and total length of devices deposited, angiographic occlusion score, and volumetric occlusion percentage. Follow-up angiographic and histologic features at 2, 6, and 10 weeks after embolization were analyzed. Groups were compared by using analysis of variance and chi2 tests. RESULTS: No significant differences were found among groups regarding aneurysm size, total device length, initial angiographic occlusion score, or procedure time. The mean number of devices for Matrix subjects was less than that for platinum coils (P = .02) and HydroCoil (P = .03). Volumetric occlusion for HydroCoil (76%) was significantly greater (P < .0001) than both platinum coils (31%) and Matrix (23%). Angiographic durability was significantly increased in the HydroCoil group compared with Matrix (P = .03). Coil compaction was found more frequently in the Matrix group (five cases, 33%) than the HydroCoil (no cases, 0%), or platinum coil groups (two cases, 22%). The Matrix group showed greater tissue reaction compared with platinum coils (P < .05). CONCLUSION: In the rabbit model, the use of HydroCoils results in improved long-term occlusion rates compared with Matrix and platinum coils. The Matrix group showed an increase in inflammation and coil compaction compared with HydroCoils and platinum coils.

Animals↗
PubMed2005

3D cerebral angiography: radiation dose comparison with digital subtraction angiography.

BACKGROUND AND PURPOSE: As the use of 3D rotational angiography (3D RA) for the evaluation of cerebral vasculature becomes more widespread, it is important to evaluate this imaging method's effect on patient radiation dose. The purpose of the study is to measure 3D RA radiation dose as compared with biplanar digital subtraction angiography (DSA). METHODS: The distribution and peak skin dose were measured for 3D RA and biplanar DSA by using an anthropomorphic skull phantom. In addition, the cumulative incident dose, summed over all images in each acquisition, was determined. Measurements were acquired for our facility's standard 3D RA acquisition mode (25 degrees /s rotational speed; 162 total frames) and other available acquisition mode selections. RESULTS: For 3D RA, the skin dose was found to be distributed across the back and sides of the skull with the peak skin dose located at the center of the back of the skull. The peak skin dose for the standard 3D RA acquisition mode was 15 mGy. For a biplanar DSA run, the peak skin dose was 58 mGy, also located at the back of the skull. The cumulative incident dose for the standard 3D RA acquisition mode was 33 mGy, compared with 53 mGy for biplanar DSA. CONCLUSION: The patient radiation dose for 3D RA is significantly lower than for biplanar DSA, by nearly a factor of 4 in peak skin dose and 40% lower in cumulative incident dose.

Angiography, Digital Subtraction↗
PubMed2005

Modified histologic technique for processing metallic coil-bearing tissue.

We developed a modified paraffin-embedding histologic technique for processing metallic coil-bearing aneurysm tissues. This modified technique was successfully employed for processing platinum coil-bearing tissue for 30 rabbit aneurysms and 6 swine aneurysms. This technique for sectioning coil-bearing aneurysms resulted in little or no tissue distortion and permitted good preservation of morphology and application of multiple advanced staining techniques. This technique is considered beneficial for studying the molecular mechanisms of aneurysm healing after coiling.

Animals↗
PubMed2005

Can neck size in elastase-induced aneurysms be controlled? A prospective study.

BACKGROUND AND PURPOSE: An earlier retrospective study indicated that the neck size of elastase-induced aneurysms could be controlled by adjusting the position of the inflated balloon. We report the current prospective study to confirm our previous work. METHODS: Ninety elastase-induced aneurysms were created in rabbits. Group 1 (n = 62) included cases in which the occlusion balloon resided low, completely within the brachiocephalic/subclavian arteries. Group 2 (n = 28) included cases in which the balloon resided high, within both the common carotid artery and brachiocephalic/subclavian arteries. Follow-up digital subtraction angiography was performed. The aneurysm sizes were measured and compared between groups. The Student t test and the Fisher exact test were used for statistical analysis. RESULTS: The mean aneurysm neck diameter and width for group 1 was significantly larger than that of group 2 (3.4 +/- 1.2 and 2.3 +/- 0.9 mm, P < .001; 3.8 +/- 1.0 and 3.3 +/- 0.9 mm, P < .05, respectively). The proportion of wide-necked aneurysms in group 1 was significantly larger than that in group 2 (29% vs 4%; P < .005). Mean dome-to-neck ratios were 1.2 +/- 0.4 and 1.7 +/- 0.7 for groups 1 and 2 (P < .005). There was no significant difference in aneurysm height between groups 1 and 2 (8.0 +/- 1.7 and 7.5 +/- 2.2 mm; P > .05). CONCLUSION: The neck size of elastase-induced aneurysm models in rabbits can be controlled by adjusting the position of the inflated balloon.

Angiography, Digital Subtraction↗
PubMed2004

Thalamic hemorrhage following carotid angioplasty and stenting.

Carotid angioplasty and stenting (CAS) has emerged as an alternative treatment of carotid stenosis for patients poorly suited for endarterectomy. Intracerebral hemorrhage following carotid revascularization is rare and thought to be related to hyperperfusion injury in most cases. Early experience suggests an increased incidence of hemorrhage following CAS as compared to endarterectomy. We describe a patient who suffered a thalamic hemorrhage following CAS. Because this hemorrhage occurred in a vascular territory unlikely to have been supplied by the treated artery, this case suggests that the mechanism of intracerebral hemorrhage following CAS may in some cases be different from the hyperperfusion hemorrhage classically described following endarterectomy.

Aged↗
PubMed2004

Cost of treating high-risk symptomatic carotid artery stenosis: stent insertion and angioplasty compared with endarterectomy.

OBJECT: Definitive data characterizing the safety and efficacy of carotid angioplasty with stent placement (CAS) for symptomatic, occlusive carotid artery (CA) disease require further refinements and standardization of techniques as well as large prospective studies on a par with the North American Symptomatic Carotid Endarterectomy Trial (NASCET). Despite the absence of such data, many surgeons have performed angioplasty and stent placement in patients with clinical or anatomical features known to add significant perioperative risk and capable of disqualifying the patients from participation in NASCET: There exists no cost analysis comparing high-risk endarterectomy with percutaneous angioplasty and stent insertion. METHODS: Forty-five patients (29 men and 16 women) with high-risk, symptomatic CA stenosis have been treated with CAS at the authors' institution since 1996. Indications for this procedure included symptomatic recurrent stenosis following CA endarterectomy (CEA), active coronary disease, high CA bifurcation, and severe medical comorbidities. A longstanding CEA computer database was screened for control patients with similar risk factors; 391 patients (276 men and 115 women) were identified. Actual cost data, duration of hospital stay, and relevant clinical data from the time of treatment until hospital discharge were collected in each patient. The median total cost of CAS was dollar 10,628, whereas that for CEA was dollar 10,148 (p = 0.495). CONCLUSIONS: In patients with high-risk, NASCET-ineligible CA stenosis there was no overall statistically significant cost difference between CEA and CAS. Given that there may not be a cost advantage for either procedure, procedural risk, efficacy, and durability should be key factors in determining the optimal treatment strategy.

Aged↗
PubMed2004

Pathogenesis, natural history, and treatment of unruptured intracranial aneurysms.

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.

Adult↗
PubMed2004

Evaluation and management of transient ischemic attack and minor cerebral infarction.

After immediate intervention for cerebral infarction or transient ischemic attack (TIA), the primary goal is secondary prevention of future cerebral ischemia and prevention of complications related to the initial ischemic event. The goals of the diagnostic evaluation are to (1) determine potential contributing mechanisms (cardioembolic, large-vessel disease of the extracranial and intracranial vessels, small-vessel disease, coagulation defects, and cryptogenic), (2) identify contributing risk factors (hypertension, hyperlipidemia, tobacco use, diabetes), and (3) complete the evaluation in a cost-effective and safe manner. We provide a sequential approach to the diagnostic evaluation of cerebral infarction or TIA to optimize diagnostic yield of testing, minimize cost and potential harm to the patient, and provide information that will change management. This systematic approach focuses on 6 important questions: (1) Are the symptoms consistent with a cerebral infarction or TIA (versus nonischemic pathology)? (2) Where does the ischemic event localize? (3) What etiologies and mechanisms of cerebral infarction and TIA are possible? (4) What is the prevalence of each potential etiology? (5) What treatments are available for this etiology? (6) What tests and studies are useful to evaluate this etiology?

Adult↗
PubMed2004

Aneurysm packing with HydroCoil Embolic System versus platinum coils: initial clinical experience.

The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA) was developed to improve the efficacy of endovascular treatment of cerebral aneurysms. The HES may reduce recurrences of aneurysms by allowing for increased packing density as compared with platinum coils. We report our initial experience with the HES in the treatment of 11 patients with cerebral aneurysms and compare findings to those in size-matched control cases treated with platinum coils. The HES provided substantially improved volumetric packing of the aneurysm lumen relative to standard platinum coils (73% vs. 32%; P=.0001).

Case-Control Studies↗
PubMed2004

The use of hydrocoil for parent artery occlusion.

The HydroCoil Embolic System (HES) comprises a platinum microcoil coated with an expansile polymer and is approved by the United States Food and Drug Administration for cerebral aneurysm occlusion. We report a series of five cases, two in the internal carotid artery and three in the vertebral artery, in which the HES was used for parent artery occlusion procedures. In each of these cases, the HES allowed rapid, short-segment occlusion.

Aortic Dissection↗
PubMed2004

A technique to circumvent subcutaneous cement tracts during percutaneous vertebroplasty.

The deposition of a subcutaneous cement tract is a potential complication of percutaneous vertebroplasty. These tracts can be a source of pain and tenderness for the patient. We describe a case of symptomatic cement deposition within a needle tract in the subcutaneous tissues that required surgical removal, and we describe a technique to prevent this complication in a second patient, by using needle redirection to cut across the cement core.

Aged↗
PubMed2003

Genetic backgrounds but not sizes of atherosclerotic lesions determine medial destruction in the aortic root of apolipoprotein E-deficient mice.

OBJECTIVE: Destruction of the elastic media is the most striking histologic feature of atherosclerotic aortic aneurysms. Apolipoprotein E-deficient (apoE-/-) mice fed a Western diet develop advanced atherosclerotic lesions in the aorta. We sought to assess the integrity of atherosclerotic aortic walls in 2 apoE-/- strains, C57BL/6 (B6) and C3H/HeJ (C3H) that differ markedly in atherosclerosis susceptibility. METHODS AND RESULTS: C3H.apoE-/- mice developed much smaller atherosclerotic lesions than did B6.apoE-/- mice after being fed a Western diet for 16 weeks, but the C3H.apoE-/- mice exhibited destruction of the elastic media, including erosion, fragmentation, and focal dilatation beneath plaques. Gelatin and casein zymography showed proteolytic activity of matrix metalloproteinases (MMPs) -9, -2, and -12 in aortic tissues and of MMP-9 and -12 in macrophages from both strains. However, C3H.apoE-/- mice showed significantly increased MMP-2 and -12 activity in aortas and macrophages compared with those from B6.apoE-/- mice. MMP-9 activity was comparable in aortic tissues of the 2 strains, but it was significantly higher in macrophages from C3H.apoE-/- than from B6.apoE-/- mice. CONCLUSIONS: Data indicate that genetic backgrounds but not sizes of atherosclerotic lesions determine medial destruction in the aortic root of apoE-/- mice and that an increase in MMP proteolytic activity might contribute to the medial destruction of aortic walls in C3H.apoE-/- mice.

Animals↗
PubMed2003

Human mesenchymal stem cells transduced with recombinant bone morphogenetic protein-9 adenovirus promote osteogenesis in rodents.

The present study was undertaken to determine whether ex vivo bone morphogenetic protein-9 (BMP-9) gene therapy using human mesenchymal stem cells (hMSCs) can induce endochondral bone formation in athymic nude rats. An in vitro study was initially performed on hMSCs to evaluate morphological changes and osteoblastic differentiation induced by replication-defective adenovirus type 5 with the cytomegalovirus promoter and either the BMP-9 (Ad-BMP-9) or beta-galactosidase (Ad-beta-gal) gene. In vivo, athymic nude rats received an injection (10(6) hMSCs transduced with recombinant adenovirus at 50 PFU/cell) into the anterior thigh musculature: Ad-BMP-9 on the left and Ad-beta-gal (control) on the right. Computed tomography scans and histological analysis were obtained 7, 14, 28, 42, 56, and 84 days postinjection. In vitro, human mesenchymal stem cells treated with Ad-BMP-9 (50 PFU/cell) showed signs of differentiation, whereas hMSCs treated with 250 and 1250 PFU/cell showed cytotoxicity. In vivo, computed tomography and histological analysis clearly demonstrated ectopic bone at hMSC/Ad-BMP-9 treatment sites, whereas the hMSC/Ad-beta-gal treatment sites showed no evidence of osteogenesis. None of the animals showed clinical evidence of toxicity. Ex vivo gene therapy with hMSC/BMP-9 may be efficacious for promoting bone formation for a variety of bone pathologies and certainly warrants further investigations.

Adenoviruses, Human↗
PubMed2003

Aneurysm growth, elastinolysis, and attempted doxycycline inhibition of elastase-induced aneurysms in rabbits.

PURPOSE: To establish the relationship between elastin degradation and aneurysm growth in New Zealand white rabbit model aneurysms, and to explore the potential for pharmacologic inhibition of elastinolysis and aneurysm growth with use of the matrix metalloproteinase (MMP) inhibitor doxycycline. MATERIALS AND METHODS: Elastase-induced, saccular aneurysms created in the right common carotid artery in 30 animals randomly divided into controls (n = 16) and doxycycline treated (n = 14) were studied. Aneurysm growth was determined by angiography and aneurysm specimens were collected at 7 and 14 days for histologic and immunohistochemical analysis. RESULTS: Aneurysms were characterized by marked elastin degradation and thickening of the arterial wall media in the absence of inflammatory cell markers. There was no evidence for expression of MMPs in the aneurysm wall at any time point. Aneurysm formation and growth were not prevented by the systemic administration of doxycycline. Mean aneurysm width increased from 3.1 +/- 0.7 mm at 3 days to 3.7 +/- 0.8 mm at 7 days and 4.2 +/- 0.8 mm at 14 days (P =.012 and P =.017, respectively). There was no statistically significant difference in aneurysm size and elastin content at any time point between doxycycline treated and control animals. CONCLUSION: Elastase-induced rabbit aneurysm formation is accompanied by total elastin destruction that was not inhibited by the administration of doxycycline. Aneurysms in this model may be caused by the initial infusion of elastase, rather than by ongoing degradation from endogenous proteases released by inflammatory cells.

Animals↗
PubMed2003

Percutaneous vertebroplasty.

This review, aimed at current practitioners of vertebroplasty, highlights recent changes in patient work-up and procedural techniques that have streamlined the authors' clinical practice. Preprocedural work-up, including history, physical examination, and adjunctive imaging techniques, are discussed. Technical details are reviewed, including types of equipment, techniques of needle placement, and utility of venography. Postprocedural issues are noted, including risk of subsequent fracture after vertebroplasty, long-term outcome of cement in the vertebral body, and utility of prophylactic vertebroplasty. Finally, the current state of evidence in support of the efficacy of vertebroplasty are discussed, with particular attention to the need for ongoing clinical trials.

Bone Cements↗