Biomedical subjects

Carlos H Timaran

Publications and source records attributed to Carlos H Timaran.

10 recordsLinked to original sources

PubMed2004

Discontinuous, staccato growth of abdominal aortic aneurysms.

BACKGROUND: To evaluate whether abdominal aortic aneurysm (AAA) growth in individual patients can be characterized as continuous or discontinuous (staccato). STUDY DESIGN: From 1996 to 2002, 609 patients presented with unruptured AAAs. Of these, 278 underwent prompt repair and 331 were observed. In this study, we included 52 patients (16% of the latter group) who had at least four CT scans and were observed for 18 months or longer without any intervention. AAA growth was defined as any increase in diameter of >/= 3 mm over any observation period(s). AAA nongrowth was defined as absence of growth for at least 6 months. Staccato growth was defined as at least one period of nongrowth combined with at least one period of growth. RESULTS: The 52 patients had a mean age of 75 +/- 8 (SD) years. The mean observation period was 42 +/- 20 months and the mean AAA diameter growth rate was 3.6 +/- 2.4 mm/y. Only 12 of these 52 patients (23%) demonstrated continuous growth. Staccato growth occurred in 34 patients (65%). Six patients (12%) showed no growth at all over 18 to 57 months (mean 30 months). No correlation was observed between initial diameter of AAAs and a patient's individual growth rate during the whole observation period (R = 0.04, p = 0.46). CONCLUSIONS: Individual AAA behavior is usually characterized by periods of nongrowth alternating with periods of growth, ie, staccato growth. Some aneurysms may have long periods of nongrowth. Accordingly, management decisions cannot be based on the presumption that observed growth rates of AAAs can be extrapolated to predict future growth rates.

Aged↗

PubMed2004

System to decrease length of stay for vascular surgery.

OBJECTIVES: Reduction of length of stay (LOS) is critical for optimal use of hospital resources. We developed and evaluated a system to aggressively reduce LOS for vascular surgery. METHOD: Key to this system, which we introduced on January 1, 2001, was appointment of a LOS officer, who communicated daily during hospitalization with patients and families about discharge planning, organized outpatient services for wound care and rehabilitation to transition patients quickly to nonhospital care, and had biweekly meetings with relevant paramedical services. LOS for 509 patients operated on in 2000 (standard group) was compared with LOS for 474 operated on in 2001 and 595 patients operated on in 2002 (LOS reduction groups). Data for all patients with aortic aneurysm, carotid artery stenosis, lower extremity critical ischemia or amputation, and foot debridement were included. RESULTS: LOS in 2000 averaged 8.5 days, compared with 5.9 days in 2001 and 5.6 days in 2002. All decreases in LOS for each diagnostic category in 2001 and 2002 were statistically significant (P = <.001-.03). There was no significant increase in readmission rate (2.2% vs 1.9% and 2.0%, respectively), mortality rate (0.8% vs 0.6% and 0.7%, respectively), or percent of patients who received endovascular treatment (18% vs 16% and 14%, respectively). These decreases in LOS saved the hospital more than US dollars 616200 in 2001, and US dollars 847550 in 2002 (US dollars 500/patient-day). CONCLUSIONS: A committed LOS officer with major specific daily responsibilities for decreasing LOS and discharging patients resulted in a 31% to 33% decrease in LOS, with important cost savings to the hospital and no negative effect on patient care.

Aged↗

PubMed2004

Variability of maximal aortic aneurysm diameter measurements on CT scan: significance and methods to minimize.

OBJECTIVES: We noted substantial differences when measuring repeatedly the same abdominal aortic aneurysm (AAA) on the same computed tomography (CT) scan. This study quantitated this variability, and methods to minimize it were developed. METHODS: The CT maximal diameter of 25 AAAs was measured by eight experienced observers, including six vascular surgeons and two radiologists, using two methods: an unstandardized protocol, and a standardized protocol using fine calipers to carefully measure the largest diameter perpendicular to the estimated aneurysm centerline, from outer aneurysm wall to outer wall. The average measurement difference between observers was calculated for each method. The average difference between each observer's measurement and the official radiology report value was also calculated. Agreement between the two measurement methods was assessed with Bland-Altman plots. RESULTS: The difference in maximal diameter measurements between each observer averaged 4.0 +/- 5.1 mm (range, 0.0-35.0 mm) with the unstandardized method. The mean measurement difference with the standardized protocol was significantly lower, and averaged 2.8 +/- 4.4 mm (range, 0.0-26.0 mm; P<.05). Measurements taken from the official radiology report differed from each of the observer's standardized measurement by an average of 5.0 +/- 6.3 mm (range, 0.0-28.0 mm). This difference was similar for both the unstandardized and standardized methods. Bland-Altman plots confirmed the wide variation of the maximal diameter measurements when the unstandardized method was compared with the standardized method (95% confidence interval, -9-9 mm). CONCLUSIONS: Routine CT maximal diameter measurement of AAAs can have substantial interobserver variability. Standardized measurement protocols can decrease, but not eliminate, this measurement variability. Thus apparent size changes based on CT measurements may represent measurement artifact rather than actual aneurysm growth or shrinkage, particularly when a standardized system is not used.

Aortic Aneurysm, Abdominal↗

PubMed2004

Predicting aneurysm enlargement in patients with persistent type II endoleaks.

OBJECTIVE: The clinical significance of type II endoleaks is not well understood. Some evidence, however, indicates that some type II endoleaks might result in aneurysm enlargement and rupture. To identify factors that might contribute to aneurysm expansion, we analyzed the influence of several variables on aneurysm growth in patients with persistent type II endoleaks after endovascular aortic aneurysm repair (EVAR). METHODS: In a series of 348 EVARs performed during a 10-year period, 32 patients (9.2%) developed type II endoleaks that persisted for more than 6 months. Variables analyzed included those defined by the reporting standards for EVAR (SVS/AAVS) as well as other endoleak characteristics. Univariate, receiver operating characteristic curve, and Cox regression analyses were used to determine the association between variables and aneurysm enlargement. RESULTS: The median follow-up period was 26.5 months (range, 6-88 months). Thirteen patients (41%) had aneurysm enlargement by 5 mm or more (median increase in diameter, 10 mm), whereas 19 (59%) had stable or shrinking aneurysm diameter. Univariate and Cox regression analyses identified the maximum diameter of the endoleak cavity, ie, the size of the nidus as defined on contrast computed tomography scan, as a significant predictor for aneurysm enlargement (relative risk, 1.12; 95% confidence interval, 1.04-1.19; P =.001). The median size of the nidus was 23 mm (range, 13-40 mm) in patients with aneurysm enlargement and 8 mm (range, 5-25 mm) in those without expansion (Mann-Whitney U test, P <.001). Moreover, receiver operating characteristic curve and Cox regression analyses showed that a maximum nidus diameter greater than 15 mm was particularly associated with an increased risk of aneurysm enlargement (relative risk, 11.1; 95% confidence interval, 1.4-85.8; P =.02). Other risk factors including gender, smoking history, hypertension, need of anticoagulation, aneurysm diameter, type of endograft used, and number or type of collateral vessels were not significant predictors of aneurysm enlargement. CONCLUSIONS: In patients with persistent type II endoleaks after EVAR, the maximum diameter of the endoleak cavity or nidus is an important predictor of aneurysm growth and might indicate the need for more aggressive surveillance as well as earlier treatment.

Aged↗

PubMed2003

Iliac artery stenting versus surgical reconstruction for TASC (TransAtlantic Inter-Society Consensus) type B and type C iliac lesions.

OBJECTIVE: The TransAtlantic Inter-Society Consensus (TASC) document did not define the best treatment for moderately severe iliac artery lesions, ie, TASC type B and type C iliac lesions, because of insufficient solid evidence to make firm recommendations. The purpose of this study was to evaluate the influence of risk factors on outcome of iliac stenting and operative procedures used to treat TASC type B and type C lesions. METHODS: Over the 5 years from 1996 to 2001, 188 endovascular and direct aortoiliac surgical reconstruction procedures were performed in 87 women and 101 men with TASC type B and type C iliac lesions and chronic limb ischemia. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) were followed to define variables. Both univariate analysis (Kaplan-Meier method) and multivariate analysis (Cox proportional hazards model) were used to determine the association between variables, cumulative patency rate, limb salvage, and survival. RESULTS: Indications for revascularization were disabling claudication (73%), limb salvage (25%), and blue toe syndrome (2%). Patients in the surgery group (n = 52) had significantly higher primary patency rates compared with patients in the stent group (n = 136) at univariate analysis (Kaplan-Meier method, log-rank test; P =.015). Primary patency rates at 1, 3, and 5 years were 85%, 72%, and 64% after iliac stenting, and 89%, 86%, and 86% after surgical reconstruction, respectively. Univariate and multivariate Cox regression analysis enabled identification of poor runoff (ie, runoff score >5 for unilateral procedures or >2.5 for bilateral outflow procedures; relative risk, 2.5; 95% confidence interval [CI], 1.4-4.2; P =.001) as the only independent predictor of decreased primary patency in all patients. However, stratified analysis including only patients with poor runoff revealed that patients undergoing iliac stenting had significantly lower primary patency rates compared with those undergoing surgical reconstruction (Kaplan-Meier method, log-rank test; P =.05). External iliac artery disease and female gender were also identified as independent predictors of decreased primary stent patency. CONCLUSIONS: Poor infrainguinal runoff is the main risk factor for decreased primary patency after surgical reconstruction and iliac stenting to treat TASC type B and type C iliac lesions. However, primary patency is less affected by poor runoff in patients undergoing surgical procedures. The presence of poor runoff, external iliac artery disease, and female gender are independent predictors of poor outcome after iliac stenting, and therefore these risk factors should determine the need for surgical reconstruction.

Angioplasty↗

PubMed2003

Iliac artery stenting in patients with poor distal runoff: Influence of concomitant infrainguinal arterial reconstruction.

OBJECTIVE: Inadequate infrainguinal runoff is considered an important risk factor for iliac stent failure. However, the influence of concomitant infrainguinal arterial reconstruction (CIAR) on iliac stent patency is unknown. This study evaluated the influence of CIAR on outcome of iliac angioplasty and stenting (IAS) in patients with poor distal runoff. METHODS: Over 5 years (1996 to 2001), 68 IAS procedures (78 stents) were performed in 62 patients with poor distal runoff (angiographic runoff score >or=5). The SVS/AAVS reporting standards were followed to define outcome variables and risk factors. Data were analyzed with both univariate analysis (Kaplan-Meier method [K-M]) and regression analysis (Cox proportional hazards model). RESULTS: Indications for iliac artery stenting were disabling claudication (59%) and limb salvage (41%). Of the 68 procedures, IAS with CIAR was performed in 31 patients (46%), and IAS alone was performed in 37 patients (54%). Patients undergoing IAS with CIAR were older (P =.03) and had more extensive and multifocal iliac artery occlusive disease, with more TASC (TransAtlantic Inter-Society Consensus) type C lesions (P =.03), compared with patients undergoing IAS alone. No other significant differences in risk factors were noted. Runoff scores between patients undergoing IAS with CIAR and those undergoing IAS alone were not significantly different (median runoff scores, 6 [range, 5-8] and 7 [range, 5-9], respectively; P =.77). Primary stent patency rate at 1, 3, and 5 years was 87%, 54%, and 42%, respectively, for patients undergoing IAS with CIAR, and was 76%, 66%, and 55%, respectively, for patients undergoing IAS. Univariate analysis revealed that primary stent patency rate was not significantly different between the 2 groups (K-M, log-rank test, P =.81). Primary graft patency rate for CIAR was 81%, 52%, and 46% at 1, 3, and 5 years, respectively. Performing CIAR did not affect primary iliac stent patency (relative risk, 1.1; 95% confidence interval, 0.49-2.47; P =.81). Overall, there was a trend toward improved limb salvage in patients undergoing IAS with CIAR, compared with those undergoing IAS alone (K-M, log rank test, P =.07). CONCLUSION: In patients undergoing IAS with poor distal runoff, CIAR does not improve iliac artery stent patency. Infrainguinal bypass procedures should therefore be reserved for patients who do not demonstrate clinical improvement and possibly for those with limb-threatening ischemia.

Adult↗

PubMed2003

Minimally invasive parathyroidectomy: how effective is preoperative sestamibi scanning?

Minimally invasive parathyroidectomy (MIP) guided by preoperative sestamibi scanning has been shown to reduce operative time, hospital stay, and cost in treating primary hyperparathyroidism. However, controversy exists over routine preoperative sestamibi scanning. The purpose of this study was to determine the utility of sestamibi scanning at our institution as part of the MIP protocol and to analyze calcium and parathyroid hormone levels as possible predictors of successful sestamibi scanning. Charts of 37 consecutive patients undergoing MIP at our institution were reviewed, and age, sex, preoperative calcium, and parathyroid (PTH) levels, invasiveness of procedure, and pathologic diagnosis were recorded. Sestamibi scans were reviewed and scored by 4 nuclear medicine faculty based on the level of suspicion for parathyroid adenoma. Neither calcium nor PTH correlated significantly with sestamibi scan score (Spearman coefficient, r = 0.075, P = 0.67 and r = 0.277, P = 0.10, respectively). Receiver-operating-characteristic (ROC) analysis showed sestamibi scanning to have sensitivity and specificity in predicting MIP completion (87% and 68%). Logistic regression showed only sestamibi scan (P = 0.038), not calcium or PTH (P = 0.977 and P = 0.767) to be predictive of MIP completion. In conclusion, sestamibi scanning effectively predicted the ability to perform MIP. However, preoperative calcium and PTH predicted neither sestamibi scan results nor completion of MIP.

Adenoma↗

PubMed2002

Effects of estrogen, progesterone, and combination exposure on interleukin-1 beta-induced expression of VCAM-1, ICAM-1, PECAM, and E-selectin by human female iliac artery endothelial cells.

The cardioprotective effect of hormone replacement therapy (HRT) in healthy, postmenopausal women is well documented. Little work has been performed on the effect of HRT in peripheral arteries. Recent work suggests that HRT may adversely affect the patency of peripheral grafts. This study investigates the in vitro effects of estrogen and/or progesterone exposure on adhesion molecule expression by normal human female iliac artery endothelial cells (HIAEC). Control and interleukin-1 beta (IL-1 beta)-stimulated HIAEC monolayers were labeled with fluorescent-tagged antibodies against the adhesion molecules VCAM-1, ICAM-1, PECAM, and E-selectin. FACS analysis was used to measure antibody-labeled adhesion molecule expression. ICAM-1 and PECAM were found to be constitutively expressed. VCAM-1 and ICAM-1 expression were significantly upregulated by IL-1 beta, while E-selectin was neither constitutively expressed nor upregulated by IL-1 beta. Pretreatment with estrogen or progesterone alone decreased IL-1 beta-stimulated VCAM-1 and ICAM-1 expression, but not to statistically significant levels. Combined hormone exposure significantly decreased, in an additive fashion, the expression of VCAM-1 and ICAM-1 in stimulated cells. This study supports extension of the beneficial effects ascribed to HRT to include the peripheral arterial endothelium of healthy women.

Adult↗

PubMed2002

Infrainguinal bypass grafting using lyophilized saphenous vein allografts for limb salvage.

Critical ischemia in patients with extensive femoropopliteal occlusive disease often ends in amputation in the absence of a suitable autologous vein for reconstruction. Cryopreserved vascular allografts have been used as an alternative conduit with poor results. Antigenicity and rejection are assumed to account for graft failure. Lyophilized vessels have demonstrated patency and structural integrity in the vascular system in our previous experimental studies. We report four patients that underwent femorodistal bypass grafting with lyophilized saphenous veins who lacked usable autologous vein for arterial reconstruction. Early graft thrombosis occurred in three patients who required major amputations. Duplex scans for graft surveillance did not reveal previous significant abnormalities. These cases demonstrate that the clinical use of lyophilized venous allografts for infrainguinal arterial reconstructions failed to yield satisfactory patency and limb salvage. Lyophilized veins therefore are not useful alternative conduits in patients with critical ischemia and no suitable autologous vein grafts.

Aged↗

PubMed2002

Predictors for adverse outcome after iliac angioplasty and stenting for limb-threatening ischemia.

OBJECTIVE: The role of iliac artery angioplasty and stenting (IAS) for the treatment of limb-threatening ischemia is not defined. IAS has been used primarily for patients with disabling claudication. Because poorer results have been shown in patients with critical ischemia after iliac artery angioplasty, the purpose of this study was to estimate the influence of risk factors on the outcome of iliac angioplasty and stent placement in patients with limb-threatening ischemia. METHODS: During a 5-year period (from 1996 to 2001), 85 iliac angioplasty and stent placement procedures (107 stents) were performed in 31 women and 43 men with limb-threatening ischemia. Patients with claudication were specifically excluded. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. The TransAtlantic InterSociety Consensus classification was used to characterize the type of iliac lesions. Both univariate (Kaplan-Meier [KM]) and multivariate analyses (Cox proportional hazards model) were used to determine the association between variables, cumulative patency, limb salvage, and survival. RESULTS: Indications for iliac angioplasty with stenting were ischemic rest pain (56%) and tissue loss (44%). Primary stenting was performed in 36 patients (42%). Stents were placed selectively after iliac angioplasty mainly for residual stenosis or pressure gradient (43%). Overall, primary stent patency rate was 90% at 1 year, 74% at 3 years, and 69% at 5 years. Primary stent patency rate was significantly reduced in women compared with men (KM, log-rank test, P <.001). Primary patency rates at 1, 3, and 5 years were 79%, 57%, and 38% for women and 92%, 88%, and 88% for men. Primary stent patency rate also was significantly reduced in patients with renal insufficiency (creatinine level, >1.6 mg/dL; KM, log-rank test, P <.001). Cox regression analysis identified female gender (relative risk, 5.1; 95% CI, 1.8 to 7.9; P =.002) and renal insufficiency (relative risk, 6.6; 95% CI, 1.6 to 14.2; P =.01) as independent predictors of decreased primary stent patency. No independent predictors for limb salvage and survival were identified. CONCLUSION: Women undergoing iliac angioplasty and stenting for limb-threatening ischemia have significantly reduced primary stent patency rates and may need additional procedures to obtain satisfactory clinical improvement and limb salvage. Patients with renal insufficiency and critical ischemia also have reduced primary stent patency rates after IAS. Limb salvage, as shown in this study, is not affected by previous iliac stent failure.

Adult↗