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Biomedical subjects

C Donayre

Publications and source records attributed to C Donayre.

At least 19 recordsLinked to original sources
PubMed2001

An abnormal dipyridamole thallium/sestamibi fails to predict long-term cardiac events in vascular surgery patients.

Recent data demonstrate that dipyridamole-thallium (DTHAL) and sestamibi (DMIBI) are not predictive of adverse perioperative cardiac events in moderate-risk patients (one or more Eagle risk factors) undergoing major elective vascular surgery. Less data are available regarding the ability of DTHAL/DMIBI to predict adverse cardiac events on long term follow-up. We sought to determine whether an abnormal DTHAL/DMIBI is predictive of adverse cardiac events on long-term follow-up in moderate-risk patients undergoing major elective vascular surgery. Patients were enrolled prospectively between June 1997 and June 1999 at West Los Angeles VA and Harbor-UCLA Medical Centers. Adverse cardiac events were defined as congestive heart failure (CHF), myocardial infarction (MI), unstable angina (USA), and ventricular arrhythmias. Follow-up was obtained via clinic visits, telephone calls, and chart review. We studied 75 patients (76% male, 24% female) with a mean age of 65 years. Operative procedures were primarily femorodistal (83%) and aortic (16%). DTHAL/DMIBI results were normal in 35 patients (47%), demonstrated reversible ischemia in 26 (35%), and showed a fixed defect alone in 14 (18%). From the follow-up results of this study we conclude that there is no association between a reversible ischemia or an abnormal (fixed or reversible) DTHAL/DMIBI and adverse cardiac events or mortality on long-term follow-up in moderate-risk patients who have undergone major vascular surgery.

Aged↗
PubMed2001

Trends in cardiac morbidity and mortality after endoluminal abdominal aortic aneurysm repair; discussion 999-1000.

HYPOTHESIS: The adverse cardiac event rate following endoluminal abdominal aortic aneurysm (EAAA) repair has decreased as experience in performing the procedure has increased. Aneurysm complexity affects the rate of adverse cardiac events. DESIGN AND PATIENTS: Data from 173 consecutive patients undergoing EAAA repair from 2 successive periods were compared. There were 82 patients in the early group (group 1) and 91 patients in the later group (group 2). MAIN OUTCOME MEASURES: Myocardial infarction, congestive heart failure, unstable angina, major dysrhythmias, death. RESULTS: The cardiac event rate was 8.5% for group 1 vs 16.5% for group 2 (P =.16). Predictors of adverse cardiac events on multivariate analysis were the use of 4 or more graft extensions (P =.04), female sex (P =.01), and number of Eagle risk factors (P<.001). There were 2 postoperative deaths (2.4%) in group 1 and 4 (4.4%) in group 2 (P =.7). CONCLUSIONS: Following EAAA repair: (1) adverse cardiac events were found to correlate with use of 4 or more graft extensions, female sex, and the number of Eagle risk factors; (2) cardiac morbidity and mortality remain significant despite greater experience and improved technology; and (3) operative mortality remains acceptably low.

Aged↗
PubMed2000

Dipyridamole-thallium/sestamibi before vascular surgery: a prospective blinded study in moderate-risk patients.

PURPOSE: This study assessed in a prospective, blinded fashion whether a reversible defect on dipyridamole-thallium (DTHAL)/sestamibi (DMIBI) can predict adverse cardiac events after elective vascular surgery in patients with one or more clinical risk factors. METHODS: Consecutive patients with one or more clinical risk factors underwent a preoperative blinded DTHAL/DMIBI. Patients with recent congestive heart failure (CHF) or myocardial infarction (MI) or severe or unstable angina were excluded. RESULTS: Eighty patients (78% men; mean age, 65 years) completed the study. Diabetes mellitus was the most frequent clinical risk factor (73%), followed by age older than 70 years (41%), angina (29%), Q wave on electrocardiogram (26%), history of CHF (7%), and ventricular ectopy (3%). The results of DTHAL/DMIBI were normal in 36 patients (45%); a reversible plus or minus fixed defect was demonstrated in 28 patients (36%), and a fixed defect alone was demonstrated in 15 patients (19%). Nine adverse cardiac events (11%) occurred, including three cases of CHF, and one case each of unstable angina, Q wave MI, non-Q wave MI, and cardiac arrest (successfully resuscitated). Two cardiac deaths occurred (2% overall mortality), one after a Q wave MI and one after CHF and a non-Q wave MI. The cardiac event rate was 14% for reversible defect and 9.8% without reversible defect (P =.71). The cardiac event rate was 12.5% (one of eight cases) for two or more reversible defects, versus 11.1% (eight of 72 cases) for fewer than two reversible defects (P = 1.0). The sensitivity rate of two or more areas of redistribution was 11% (95% CI, 0.3%-48%), the specificity rate was 90%, and the positive and negative predictive values were 12.5% and 89%, respectively. CONCLUSION: Our study demonstrated no association between reversible defects on DTHAL/DMIBI and adverse cardiac events in moderate-risk patients undergoing elective vascular surgery.

Aged↗
PubMed2000

Abdominal aortic aneurysm rupture following endoluminal graft deployment: report of a predictable event.

PURPOSE: To describe the predictability of an abdominal aortic aneurysm (AAA) rupture secondary to a type II endoleak following stent-graft exclusion. METHODS AND RESULTS: An 81-year-old man with an enlarging AAA underwent endovascular repair using an AneuRx aortic stent-graft, but a type II endoleak fed by an accessory renal artery was detected at postprocedural computed tomography (CT). Surveillance CT scans at 6 and 16 months showed an increase in the aneurysm diameter and endoleak volume, but the patient refused advised treatment to close the leak. He suffered a fatal aneurysm rupture 24 months after endografting. Retrospective analysis of CT data documented progressive aneurysm enlargement that correctly predicted the rupture. CONCLUSIONS: Type II endoleaks can lead to aneurysm rupture. Three-dimensional (3D) spiral CT angiography offers an opportunity to track endoleak volume and the effect of exposure to systemic pressure on the aneurysm sac.

Aged↗
PubMed1999

Endovascular vs open abdominal aortic aneurysm repair: a comparison of cardiac morbidity and mortality.

HYPOTHESIS: Adverse cardiac event rates following endovascular abdominal aortic aneurysm (EAAA) and open abdominal aortic aneurysm (OAAA) repair are similar. We also hypothesized that the Eagle criteria (Q wave on electrocardiogram, diabetes, angina, congestive heart failure, age >70 years, and ventricular ectopy) are useful predictors of cardiac events in patients undergoing EAAA repair. DESIGN: Prospective (patients undergoing EAAA repair) and retrospective (patients undergoing OAAA repair). SETTING: Public teaching and Veterans Affairs medical centers. PATIENTS: Eighty-three EAAA and 63 OAAA repairs. MAIN OUTCOME MEASURES: Myocardial infarction, congestive heart failure, and cardiac death. RESULTS: Patients with EAAA were older (73 vs 68 years, P=.003). There were no differences in the mean number of Eagle criteria (1.2 vs 1.3), cardiac event rates (6% vs 4.8%), or mortalities (3.6% vs 4.8%). Within the EAAA group, congestive heart failure (P=.005) and Q wave on electrocardiogram (P=.006) were the only predictors of cardiac events. CONCLUSIONS: Patients undergoing OAAA and EAAA repair had similar cardiac event rates and mortality. In patients undergoing EAAA repair, history of congestive heart failure and Q wave on electrocardiogram were predictors of cardiac events.

Aged↗
PubMed1999

Central venous injuries of the subclavian-jugular and innominate-caval confluences.

Injuries to the central venous system can result from penetrating trauma or iatrogenic causes. Injuries to major venous confluences can be particularly problematic, because the clavicle and sternum seriously limit exposure of the injury site. We report our institution's experience with central venous injuries of the subclavian-jugular and innominate-caval venous confluences. Significant injuries of the subclavian-jugular venous confluence frequently result from penetrating trauma, while injuries to the innominate-caval confluence are usually catheter-related. Median sternotomy provides adequate exposure of the innominate-caval confluence, while exposure of the subclavian-jugular venous confluence requires extension of the median sternotomy incision into the neck and resection of the clavicle. The literature is reviewed.

Adolescent↗
PubMed1998

Wallgraft endoprosthesis: initial canine evaluation.

This study evaluated the in vivo deployment and the healing characteristics of a self-expanding endoluminal graft [Wallgraft (WG) Endoprosthesis] in a canine (n = 22) aorta. The WG consisted of a 10 or 12 mm x 7.5 cm Wallstents (Schneider, Inc.) covered with polyethylene terephthalate (Dacron) graft material. Twenty-two WGs were deployed using fluoroscopic guidance. Devices were oversized approximately 10 per cent. Intravascular ultrasound (IVUS) was repeated, and balloon expansion along the length of the WG was performed to assure maximum expansion. WGs were evaluated with IVUS, angiography, and histology at 14 (n = 4), 30 (n = 4), 90 (n = 4), 180 (n = 5), and 365 (n = 5) days. Predeployment aortic diameters were 9.9 +/- 1 mm. Mid-WG diameters were 9.0 +/- 0.8 mm before balloon dilation and 9.2 +/- 0.5 mm after dilation with 8- (n = 1), 10- (n = 16), and 12- (n = 5) mm balloons. Twenty-two of 23 devices were deployed accurately with good apposition and aortic flow after deployment. On explant, all of the covered grafts were widely patent on IVUS and angiogram. Four explants demonstrated gaps (due to WG taper) between the proximal or distal ends of the graft on IVUS. The device length (9.1 + 0.5 cm) did not change significantly after deployment. Histologically at 6 months and 1 year the lumens were cell-lined. Scanning electron micrography demonstrated endothelial-like cells. This study demonstrates the ability of a WG to be accurately deployed and maintain excellent patency. Balloon expansion after deployment did not significantly increase the diameter. Clinical evaluation of this device is in progress.

Animals↗
PubMed1997

Intravascular ultrasound: the ultimate tool for abdominal aortic aneurysm assessment and endovascular graft delivery.

Intravascular ultrasound (IVUS) imaging is a relatively new, rapidly evolving technology that enables precise catheter-based assessment of the dimensions and morphology of vascular structures and lesions. In extensive preclinical laboratory developmental studies and in clinical cases of endograft deployment for treatment of abdominal aortic aneurysms, we have found IVUS invaluable for determining key parameters of aortic morphology before and during interventions and for assessing the accuracy of deployment after device placement. By combining the IVUS data with information obtained from angiography, magnetic resonance imaging, and computed tomography (axial and three-dimensional reconstructions), we have been able to size devices and choose optimal fixation sites to prevent endoleaks and maintain luminal patency acutely and in the long term.

Angioplasty↗
PubMed1997

Endograft repair of an aortic pseudoaneurysm following gunshot wound injury: impact of imaging on diagnosis and planning of intervention.

PURPOSE: To describe the endovascular treatment of a gunshot injury to the visceral aorta and the role of various imaging modalities in the staging and planning of the endograft procedure. METHODS AND RESULTS: The bullet entered the aorta posteriorly beneath the origin of the superior mesenteric artery and traversed the wall in a tangential manner entering the lumen proximal to the renal arteries. Intravascular ultrasound (IVUS) imaging and spiral computed tomography (CT) identified the injury that the initial angiograms failed to demonstrate. Combined use of IVUS and CT imaging enabled observation of the evolution of a pseudoaneurysm until an interval when endograft exclusion was possible. A stent-graft was customized based on precise IVUS and CT dimensional data and implanted successfully through an arteriotomy in the common femoral artery 3 weeks after the initial injury. Three-month follow-up imaging demonstrated continued exclusion of the pseudoaneurysm, and the patient remains well at 16 months. CONCLUSIONS: IVUS and spiral CT scans were instrumental in identifying an arteriographically undetected aortic injury. The combined imaging modalities also helped determine the timing for the endovascular procedure and provided the precise measurements for device fabrication and deployment.

Adult↗
PubMed1997

Noniatrogenic pediatric vascular trauma: a ten-year experience at a level I trauma center.

We retrospectively reviewed all pediatric patients (< 18 years old) who presented to a Level I trauma center from 1984 to 1994 with noniatrogenic vascular trauma. There were 48 patients (42 male and 6 female) ages 2 to 17 years. Mechanism of injury included gunshot wounds (34) stab wounds (10), and blunt trauma (4). The lower extremities were most commonly injured (31), followed by upper extremity (17), trunk (8), and neck (4). Twenty-one (44%) patients had associated nonvascular injuries (primarily orthopedic or peripheral nerve). Eighteen (37%) patients underwent preoperative angiography for suspected extremity (15) or carotid injuries (3). Twenty-nine patients went to surgery without angiography based on severe ischemia (11) or hemorrhage (18). Arterial injuries (45) were managed by interposition reverse saphenous vein graft (16), primary repair (15), ligation (5), or other operative (5) and nonoperative treatment (4). Venous injuries (15) were treated with primary repair (8), patch (3), ligation (3), and nonoperative management (1). Fasciotomy was performed in six (12%). There were three deaths (6%), all due to aortic and/or caval injuries. Limb salvage in survivors was 100 per cent. There were no complications from angiography. Postoperative duplex scans demonstrated patency in six of the seven patients studied with venous injuries. We conclude that 1) noniatrogenic pediatric vascular trauma is uncommon, and 2) using an aggressive approach to both the diagnosis and treatment of these injuries can achieve excellent limb salvage rates with a low morbidity and mortality.

Adolescent↗
PubMed1996

Cardiac assessment prior to vascular surgery: is dipyridamole-sestamibi necessary?

Dipyridamole-sestamibi (PMIBI) is recommended prior to vascular surgery in patients with > or = 1 Eagle criteria (Q waves, history of ventricular ectopy, diabetes, advanced age, and/or angina). To review our cardiac morbidity and mortality and the need for preoperative PMIBI, we reviewed 109 consecutive patients with a mean age of 59 years who underwent 145 elective major vascular procedures over a 1-year period. Seventy patients (with a mean of 0.8 Eagle criteria) underwent 92 vascular procedures without preoperative PMIBI and without coronary revascularization. Thirty-one patients (with a mean of 1.1 Eagle criteria) underwent 39 procedures without coronary revascularization following PMIBI, which showed reversible ischemia in seven and a fixed defect in 10; findings were normal in 14. Preoperative coronary bypass or angioplasty was limited to eight patients (14 procedures, mean of 1.6 Eagle criteria) who had unstable angina with (2 patients) or without (6 patients) acute myocardial infarction. There were four perioperative myocardial infarctions (2.8%), seven cardiac events overall (4.8%), and one cardiac death (0.7%). Three (43%) of the seven cardiac events occurred in patients with a normal scan or fixed defect on PMIBI imaging. In the absence of unstable angina, PMIBI had a sensitivity of only 25% and a specificity of 80% for cardiac events. We conclude that among patients without severe cardiac symptoms (1) PMIBI has a very limited ability to identify patients at risk for cardiac complications, and (2) preoperative PMIBI is neither necessary nor cost-effective.

Age Factors↗
PubMed1996

Comparison of the deployment and healing of thin-walled expanded PTFE stented grafts and covered stents.

This study evaluated the deployment and short-term healing of thin-walled expanded polytetrafluoroethylene (ePTFE) stented grafts and covered stents as endoluminal prostheses in normal canine aortas and in an abdominal aortic aneurysm (AAA) model. Stented grafts consisted of a 7 cm length of 3 mm internal diameter ePTFE graft (Impra, Inc., Tempe, Ariz.) with two P-188 Palmaz stents (Johnson & Johnson Interventional Systems, Warren, N.J.) deployed along the inner surface of the ends of the graft to secure the prosthesis to the arterial wall. Covered stents were fabricated by placing a 3.7 cm length of 3 mm internal diameter thin-walled ePTFE graft over a P-394 Palmaz stent. Four covered stents and four stented graft prostheses (two of each prototype in the normal canine aorta and AAA model) were implanted in eight animals. One prosthesis of each type in each model was removed at 30 days and one at 60 days. Prior to removal, prostheses were evaluated by CT scan, arteriography, and intravascular ultrasound imaging with values compared to those obtained when the prostheses were deployed. Gross inspection and microscopic evaluation were performed at scheduled explantation. In general, the stented grafts were more difficult to accurately deploy. Healing and maintenance of long-term patency without significant luminal obstruction or occlusion occurred in only one 30-day sample in a normal canine aorta. The 30-day stented graft specimen that had been implanted in an AAA and required the addition of a covered stent to seal a maldeployment of the distal segment was also patent. The 60-day stented graft in the normal canine aorta was occluded with narrowing of the graft between the stents. The 60-day stented graft in the AAA was patent with one central fold and thrombus occupying approximately 20% to 30% of the lumen at this site. In contrast, the covered stent devices were less difficult to accurately deploy. All of the covered stent devices were patent with well-incorporated surfaces. Deployment of covered stents was more accurate and less complicated compared to stented grafts. All patent endoluminal prostheses and stent surfaces were well incorporated into aortic tissues. Problems with graft narrowing, folding, and subsequent thrombosis occurred in the unstented segments of the stented grafts. These preliminary findings support the further development and use of completely supported (stented) devices as endoluminal prostheses.

Angioplasty, Balloon↗
PubMed1996

Abdominal aortic aneurysm screening in elderly males with atherosclerosis: the value of physical exam.

The purpose was 1) To assess the prevalence of abdominal aortic aneurysms (AAA) in elderly males with atherosclerosis and 2) to evaluate the value of physical exam (PE) by a vascular surgeon in detecting AAA. A total of ninety-six males older than 55 years referred to vascular surgery clinic with atherosclerotic disease were screened prospectively with PE by a vascular surgeon, followed by ultrasonography (US). Atherosclerosis was documented by ankle brachial index and duplex US. Patients who had recently undergone a vascular procedure, aortography, laparotomy, abdominal computed tomography, or US were excluded. Mean age was 67 years. Patients were 67 per cent Caucasian, 32 per cent black, and 1 per cent Hispanic. Presenting complaints were related to claudication (83%), carotid disease (19%), both (3%), and subclavian stenosis (1%). Patient characteristics included cigarette smoking (85%), hypertension (67%), cardiac disease (51%), diabetes (45%), stroke (18%), and chronic obstructive pulmonary disease (8%). One (1%) 3.7 cm AAA was detected by US. Sensitivity of PE was 100 per cent and specificity 92 per cent. Twenty-two (23%) patients were too obese for us to feel the aortic pulse. Screening cost was $14,250. The prevalence of AAA in this population is very low. AAA screening should be reserved for patients with a positive PE or who are too obese for the examiner to feel the aortic pulse.

Aged↗
PubMed1995

[Therapy of an abdominal aortic aneurysm using transfemoral endovascular implantation of a bifurcation prosthesis].

Transfemoral intraluminal placement of a woven-dacron bifurcation prosthesis was undertaken to bridge an infrarenal aortic aneurysm (4.6 cm diameter) in a 65-year-old man with chronic coronary heart disease. The Chuter-Gianturco introducing system was used via the right femoral artery to anchor the prosthesis immediately below the origins of the renal arteries. After fixing the right branch of the prosthesis the left one was secured via the left femoral artery. No leakage was demonstrated on the 7th post-operative day and the aneurysm was satisfactorily bridged. Regular follow-up tests showed a normal circulation. Spiral computed tomography after 18 months confirmed complete thrombosis of the aneurysm.--This case shows that the described method is a promising alternative in the treatment of abdominal aneurysm.

Aged↗
PubMed1995

Comparison of the utility of CT scans and intravascular ultrasound in endovascular aortic grafting.

Using CT scans and intravascular ultrasound (IVUS), aortic, aneurysm neck, and endoluminal graft cross-sectional dimensions were compared in a canine model before and after placement of endoluminal grafts in normal aortas (n = 10) and in artificially constructed abdominal aortic aneurysms (n = 15). Measurement of diameters (n = 83) revealed an average difference or bias between imaging modalities of 0.17 +/- 0.92 mm. Measurements obtained using IVUS were slightly larger than CT values (8.84 +/- 1.0 vs. 8.65 +/- 1.1, p < 0.03) but correlated very well by linear regression analysis (r = 0.948, p < 0.02). Analysis of cross-sectional area (n = 44) revealed an average difference or bias of 7.21 +/- 7.76 mm2 between the two modalities. Again IVUS measurements were larger than CT measurements (65.0 +/- 16.5 vs. 57.9 +/- 11.9, p < 0.001) and linear regression analysis showed less correlation (r = 0.897, p < 0.001). Qualitative assessment of the graft and stent characteristics was more precise using IVUS. Graft folding, stent-aorta interfaces, and thrombus formation were easily identified by IVUS, whereas these more subtle characteristics were missed by CT scanning and arteriography. These studies demonstrate that IVUS measurements were slightly larger than CT values; however, both modalities demonstrate small bias and good correlation. Qualitative analysis of the aneurysmal aorta and endoluminal graft using IVUS is comparable to and in some respects more detailed than measurements from CT scanning and arteriography.

Animals↗
PubMed1995

The role of cinefluoroscopy and intravascular ultrasonography in evaluating the deployment of experimental endovascular prostheses.

PURPOSE: This study compares the utility of cineangiography and real-time intravascular ultrasonography (IVUS) in achieving successful deployment of endovascular prostheses. METHODS: Five types of 5 cm long, 8 mm internal diameter polyester vascular grafts were secured in the infrarenal aorta of mongrel dogs by 18 mm long Palmaz balloon expandable vascular stents sutured to each end of the prostheses. The endovascular prostheses were delivered by crimping the stents at the ends of the grafts onto a 10 mm outside diameter, 8 cm long polyethylene balloon-dilation catheter. Real-time IVUS of the procedure was provided by a 0.035-inch, 20 MHz imaging element passed through the guide wire lumen in the balloon catheter. Two prostheses of each type were implanted, with one removed at 30 days and the other at 60 days for analysis. RESULTS: At implantation, both angiography and IVUS provided information regarding the choice of site for placement of the device and sizing of the aortic lumen. Real-time IVUS enhanced the information obtained by cineangiography by displaying tomographic views of the vessel anatomy, enabling determination of cross-sectional areas, assessing full stent expansion, and providing information regarding surface topography along the length of the prostheses. Several critical observations were apparent only on IVUS, including incomplete initial stent expansion during two procedures evidenced by pulsation of the aortic wall independent of the stent and movement of unstented segments of thin-walled grafts. Some of these observations led to further interventions at the time of deployment. At death, a comparison of cineangiography, IVUS, and ultrafast computed tomography outlined lumenal continuity and areas of irregularity, thrombus, or narrowing, with IVUS being more sensitive than cineangiography or computed tomography for determining most parameters. CONCLUSIONS: We conclude that IVUS is a promising alternative method for precise placement of intravascular grafts.

Animals↗