Percutaneous intervention in peripheral artery disease improves calf muscle phosphocreatine recovery kinetics: a pilot study

We hypothesized that percutaneous intervention in the affected lower extremity artery would improve calf muscle perfusion and cellular metabolism in patients with claudication and peripheral artery disease (PAD) as measured by magnetic resonance imaging (MRI) and spectroscopy (MRS). Ten patients with symptomatic PAD (mean ± SD: age 57 ± 9 years; ankle-brachial index (ABI) 0.62 ± 0.17; seven males) were studied 2 months before and 10 months after lower extremity percutaneous intervention. Calf muscle phosphocreatine recovery time constant (PCr) in the revascularized leg was measured by (31)P MRS immediately after symptom-limited exercise on a 1.5-T scanner. Calf muscle perfusion was measured using first-pass gadolinium-enhanced MRI at peak exercise. A 6-minute walk and treadmill test were performed. The PCr recovery time constant improved significantly following intervention (91 ± 33 s to 52 ± 34 s, p < 0.003). Rest ABI also improved (0.62 ± 0.17 to 0.93 ± 0.25, p < 0.003). There was no difference in MRI-measured tissue perfusion or exercise parameters, although the study was underpowered for these endpoints. In conclusion, in this pilot study, successful large vessel percutaneous intervention in patients with symptomatic claudication, results in improved ABI and calf muscle phosphocreatine recovery kinetics.

The effect of ezetimibe on peripheral arterial atherosclerosis depends upon statin use at baseline

BACKGROUND

Both statins and ezetimibe lower LDL-C, but ezetimibe's effect on atherosclerosis is controversial. We hypothesized that lowering LDL-C cholesterol by adding ezetimibe to statin therapy would regress atherosclerosis measured by magnetic resonance imaging (MRI) in the superficial femoral artery (SFA) in peripheral arterial disease (PAD).

METHODS

Atherosclerotic plaque volume was measured in the proximal 15-20 cm of the SFA in 67 PAD patients (age 63 ± 10, ABI 0.69 ± 0.14) at baseline and annually × 2. Statin-naïve patients (n=34) were randomized to simvastatin 40 mg (S, n=16) or simvastatin 40 mg+ezetimibe 10mg (S+E, n=18). Patients already on statins but with LDL-C >80 mg/dl had open-label ezetimibe 10mg added (E, n=33). Repeated measures models estimated changes in plaque parameters over time and between-group differences.

RESULTS

LDL-C was lower at year 1 in S+E (67 ± 7 mg/dl) than S (91 ± 8 mg/dl, p<0.05), but similar at year 2 (68 ± 10 mg/dl vs. 83 ± 11 mg/dl, respectively). Plaque volume did not change from baseline to year 2 in either S+E (11.5 ± 1.4-10.5 ± 1.3 cm(3), p=NS) or S (11.0 ± 1.5-10.5 ± 1.4 cm(3), p=NS). In E, plaque progressed from baseline to year 2 (10.0 ± 0.8-10.8 ± 0.9, p<0.01) despite a 22% decrease in LDL-C.

CONCLUSIONS

Statin initiation with or without ezetimibe in statin-naïve patients halts progression of peripheral atherosclerosis. When ezetimibe is added to patients previously on statins, peripheral atherosclerosis progressed. Thus, ezetimibe's effect on peripheral atherosclerosis may depend upon relative timing of statin therapy.

Low-density lipoprotein lowering does not improve calf muscle perfusion, energetics, or exercise performance in peripheral arterial disease

OBJECTIVES

We hypothesized that low-density lipoprotein (LDL) reduction regardless of mechanism would improve calf muscle perfusion, energetics, or walking performance in peripheral arterial disease (PAD) as measured by magnetic resonance imaging and magnetic resonance spectroscopy.

BACKGROUND

Statins improve cardiovascular outcome in PAD, and some studies suggest improved walking performance.

METHODS

Sixty-eight patients with mild to moderate symptomatic PAD (age 65 ± 11 years; ankle-brachial index [ABI] 0.69 ± 0.14) were studied at baseline and annually for 2 years after beginning simvastatin 40 mg (n = 20) or simvastatin 40 mg/ezetimibe 10 mg (n = 18) if statin naïve, or ezetimibe 10 mg (n = 30) if taking a statin. Phosphocreatine recovery time was measured by (31)P magnetic resonance spectroscopy immediately after symptom-limited calf exercise on a 1.5-T scanner. Calf perfusion was measured using first-pass contrast-enhanced magnetic resonance imaging with 0.1 mM/kg gadolinium at peak exercise. Gadolinium-enhanced magnetic resonance angiography was graded. A 6-min walk and a standardized graded Skinner-Gardner exercise treadmill test with peak Vo(2) were performed. A repeated-measures model compared changes over time.

RESULTS

LDL reduction from baseline to year 2 was greater in the simvastatin 40 mg/ezetimibe 10 mg group (116 ± 42 mg/dl to 56 ± 21 mg/dl) than in the simvastatin 40 mg group (129 ± 40 mg/dl to 90 ± 30 mg/dl, p < 0.01). LDL also decreased in the ezetimibe 10 mg group (102 ± 28 mg/dl to 79 ± 27 mg/dl, p < 0.01). Despite this, there was no difference in perfusion, metabolism, or exercise parameters between groups or over time. Resting ABI did improve over time in the ezetimibe 10 mg group and the entire study group of patients.

CONCLUSIONS

Despite effective LDL reduction in PAD, neither tissue perfusion, metabolism, nor exercise parameters improved, although rest ABI did. Thus, LDL lowering does not improve calf muscle physiology or functional capacity in PAD. (Comprehensive Magnetic Resonance of Peripheral Arterial Disease; NCT00587678).

The plasma microparticle proteome

All cell types shed ectosomes and exosomes, collectively known as microparticles (MP; 0.1 to 1.5 μm in diameter), when activated or stressed; normal human plasma contains ~2 μg MP protein/mL. The cellular composition of plasma MP is altered in many diseases, including acute coronary syndrome, diabetes mellitus, sepsis, and sickle cell disease. We measured the plasma MP protein composition of 42 patients (median age 69.5 years, most with cardiovascular disease) by label-free liquid chromatography coupled to tandem mass spectrometry. Among 458 proteins detected with high confidence (identified by at least two unique peptides with SEQUEST XCor (Thermo Electron Corp., San Jose, CA) ≥ 2.0, 2.2, and 3.3 for charge states +1, +2, and +3, respectively), 130 were present in most patients, representing a "core" set of plasma MP proteins. This core is enriched in cytoskeletal, integrin complex, and hemostasis proteins, and spectral counts of several proteins correlate with patient age and gender. We conclude that the MP proteome may be a useful and reliable source of biologically relevant disease biomarkers.

Outcomes of covered kissing stent placement compared with bare metal stent placement in the treatment of atherosclerotic occlusive disease at the aortic bifurcation

PURPOSE

To review the outcomes with the use of balloon-expandable covered iliac kissing stents as compared with bare metal stents in the treatment of atherosclerotic disease at the aortic bifurcation.

MATERIALS AND METHODS

A review of consecutive patients from a single institution with atherosclerotic occlusive disease at the aortic bifurcation treated with balloon-expandable kissing stents was performed between January 1, 2002, and September 1, 2007. Fifty-four patients were identified and divided into two groups: those with bare metal stents and those with covered stents. Technical and clinical success (Fontaine classification), complications, and patency at follow-up were documented.

RESULTS

Twenty-six patients (17 men, nine women; mean age, 61 years; age range, 39-79 years) received covered stents and 28 patients (15 men, 13 women; mean age, 61 years; age range, 38-82 years) received bare metal stents. Technical success was achieved in 100% of patients in both groups. Major complications occurred in three of the 26 (11%) with covered stents (P = .66) and two of the 28 patients (7%) with bare metal stents. The median follow-up was 21 months (20 months for covered stents vs 25 months for bare metal stents; range, 1-62 months). Twenty-two of the 26 patients (85%) with covered stents had sustained improvement in clinical symptoms during the follow-up period compared with 15 of the 28 patients (54%) with bare metal stents (P = .02). Primary patency rates at 1 and 2 years were 92% and 92%, respectively, for covered stents and 78% and 62% for bare metal stents (P = .023).

CONCLUSIONS

The use of covered balloon-expandable kissing stents for atherosclerotic aortic bifurcation occlusive disease provides superior patency at 2 years as compared with bare metal balloon-expandable stents.

Multifactorial determinants of functional capacity in peripheral arterial disease: uncoupling of calf muscle perfusion and metabolism

OBJECTIVES

We aimed to investigate the pathophysiology of peripheral arterial disease (PAD) by examining magnetic resonance imaging (MRI) and spectroscopic (MRS) correlates of functional capacity.

BACKGROUND

Despite the high prevalence, morbidity, and cost of PAD, its pathophysiology is incompletely understood.

METHODS

Eighty-five patients (age 68 +/- 10 years) with mild-to-moderate PAD (ankle-brachial index 0.69 +/- 0.14) had their most symptomatic leg studied by MRI/MRS. Percent wall volume in the superficial femoral artery was measured with black blood MRI. First-pass contrast-enhanced MRI calf muscle perfusion and (31)P MRS phosphocreatine recovery time constant (PCr) were measured at peak exercise in calf muscle. All patients underwent magnetic resonance angiography (MRA), treadmill testing with maximal oxygen consumption measurement, and a 6-min walk test.

RESULTS

Mean MRA index of number and severity of stenoses was 0.84 +/- 0.68 (normal 0), % wall volume 74 +/- 11% (normal 46 +/- 7%), tissue perfusion 0.039 +/- 0.015 s(-1) (normal 0.065 +/- 0.013 s(-1)), and PCr 87 +/- 54 s (normal 34 +/- 16 s). MRA index, % wall volume, and ankle-brachial index correlated with most functional measures. PCr was the best correlate of treadmill exercise time, whereas calf muscle perfusion was the best correlate of 6-min walk distance. No correlation was noted between PCr and tissue perfusion.

CONCLUSIONS

Functional limitations in PAD are multifactorial. As measured by MRI and spectroscopy, atherosclerotic plaque burden, stenosis severity, tissue perfusion, and energetics all play a role. However, cellular metabolism is uncoupled from tissue perfusion. These findings suggest a potential role for therapies that regress plaque, increase tissue perfusion, and/or improve cellular metabolism. (Comprehensive Magnetic Resonance of Peripheral Arterial Disease; NCT00587678).

Unusual anomaly complicating abdominal aortic aneurysm repair: anterior inferior vena cava

This case illustrates an unusual anomaly of the great veins. To our knowledge, these are the first published photographs of the vena cava traversing anterior to the distal aorta. This anatomic variant caused minor technical problems during open abdominal aortic aneurysm repair.

Limb stress-rest perfusion imaging with contrast ultrasound for the assessment of peripheral arterial disease severity

OBJECTIVES

We hypothesized that stress-rest perfusion imaging of skeletal muscle in the lower extremity with contrast-enhanced ultrasound (CEU) could evaluate the severity of peripheral arterial disease (PAD).

BACKGROUND

Perfusion imaging may provide valuable quantitative information on PAD, particularly in patients with diabetes in whom microvascular functional abnormalities are common.

METHODS

Study subjects included 26 control subjects and 39 patients with symptomatic PAD, 19 of whom had type 2 diabetes mellitus. A modified treadmill exercise test was performed to determine exercise time to development of claudication. Multilevel pulse-volume recordings and ankle-brachial index (ABI) at rest and post-exercise ABI were measured in both extremities. Microvascular blood flow in the gastrocnemius and soleus muscles was measured at rest and after 2 min of calibrated plantar-flexion exercise.

RESULTS

During exercise, claudication did not occur in normal subjects and occurred earlier in PAD patients with diabetes than without (median time 1.2 min [95% confidence interval (CI) 0.6 to 2.5] vs. 3.0 min [95% CI 2.1 to 6.0], p < 0.01). Compared to control subjects, patients with PAD had lower skeletal muscle blood flow during plantar-flexion exercise and lower flow reserve on CEU. After adjusting for diabetes, the only diagnostic tests that predicted severity of disease by claudication threshold were CEU exercise blood flow and flow reserve (odds ratios 0.67 [95% CI 0.51 to 0.88; p = 0.003] and 0.64 [95% CI 0.46 to 0.89, p = 0.008], respectively). A quasi-likelihood information analysis incorporating all non-invasive diagnostic tests indicated that the best models for predicting severity of disease were the combination of diabetes and either exercise blood flow or flow-reserve on CEU.

CONCLUSIONS

Perfusion imaging of limb skeletal during exercise and measurement of absolute flow reserve can provide valuable information on the severity PAD. This strategy may be useful for evaluating the total impact of disease in patients with complex disease or those with coexisting functional abnormalities of flow regulation.

Calf muscle perfusion at peak exercise in peripheral arterial disease: measurement by first-pass contrast-enhanced magnetic resonance imaging

PURPOSE

To develop a contrast-enhanced magnetic resonance (MR) technique to measure skeletal muscle perfusion in peripheral arterial disease (PAD).

MATERIALS AND METHODS

A total of 11 patients (age = 61 +/- 11 years) with mild to moderate symptomatic PAD (ankle-brachial index [ABI] = 0.75 +/- 0.08) and 22 normals were studied using an MR-compatible ergometer. PAD and normal(max) (Nl(max); N = 11) exercised to exhaustion. Nl(low) (N = 11) exercised to the same workload achieved by PAD. At peak exercise, 0.1 mm/kg of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was infused at 3-4 cm(3)/second followed by a saline flush at the same rate. A dual-contrast gradient echo (GRE) sequence enabled simultaneous acquisition of muscle perfusion and arterial input function (AIF). The perfusion index (PI) was defined as the slope of the time-intensity curve (TIC) in muscle divided by the arterial TIC slope.

RESULTS

Median workload was 120 Joules in PAD, 210 Joules in Nl(low), and 698 Joules in Nl(max) (P < 0.001 vs. Nl(low) and PAD). Median PI was 0.29 in PAD (25th and 75th percentiles [%] = 0.20, 0.40), 0.48 in Nl(low) (25th, 75th % = 0.36, 0.62; P < 0.02 vs. PAD), and 0.69 in Nl(max) (25th, 75th % = 0.5, 0.77; P < 0.001 vs. PAD). Area under the ROC-curve for PI differentiating patients from Nl(max) was 0.95 (95% confidence interval [CI] = 0.77-0.99).

CONCLUSION

Peak-exercise measurement of lower limb perfusion with dual-contrast, first-pass MR distinguishes PAD from normals. This method may be useful in the study of novel therapies for PAD.

Reproducibility and reliability of atherosclerotic plaque volume measurements in peripheral arterial disease with cardiovascular magnetic resonance

A high resolution, noninvasive approach to quantify atherosclerotic plaque in the peripheral vasculature could have significant clinical and research utility. Seventeen patients with peripheral arterial disease (PAD) were studied in a 1.5T CMR scanner. Atherosclerotic plaque volume in the superficial femoral artery was measured and interobserver, intraobserver, and test-retest variability determined. Nineteen vessels were studied with mean acquisition time of 13.1 minutes per vessel. Mean plaque volume was 7.27 +/- 3.73 cm3. Intra-observer intraclass correlation was R = 0.997, inter-observer was R = 0.987, and test-retest reproducibility was R = 0.996. Thus, high resolution measurement of plaque volume in PAD is reliable and reproducible.

Diagnosis of Aortoenteric Fistulas with CT Angiography

PURPOSE

To describe the diagnostic findings of primary and secondary aortoenteric fistulas (AEFs) at computed tomographic (CT) angiography in a cohort of patients known to have AEF and to correlate those findings with those from endoscopic gastroduodenoscopy (EGD) and surgery.

MATERIALS AND METHODS

CT angiography was performed in nine patients with AEF. There were four men and five women aged 43-85 years (mean age, 67 years). All CT angiograms were retrospectively reviewed for signs of AEF. Reports from EGD, surgery, and pathologic examination were also reviewed.

RESULTS

One patient had a primary AEF, and eight patients had a secondary AEF. Findings at CT angiography were suggestive of the diagnosis in all nine patients. The two definitive CT angiographic findings were identification of the graft within the bowel lumen in two patients (22%) and active extravasation in one patient (11%), allowing the definitive diagnosis in three of the nine patients (33%). Secondary signs, which helped predict the high likelihood of the diagnosis but could also be seen in graft infection or inflammation without AEF, were as follows (in descending order of frequency): effacement of the periaortic or perigraft fat plane and the fat plane between the aorta and bowel (nine patients, 100%), perigraft soft tissue (nine patients, 100%), bowel wall thickening adjacent to the graft (eight patients, 89%), perigraft fluid (seven patients, 78%), perigraft hematoma (six patients, 67%), pseudoaneurysm or aneurysm bulge (six patients, 67%), ectopic gas (five patients, 56%), and dystrophic vascular graft calcification (one patient, 11%). The diagnosis was confirmed surgically in seven patients and with clinical follow-up in two.

CONCLUSION

CT angiography is well suited for helping make or suggesting the diagnosis of AEF and is potentially more accurate than EGD.

CTA and MRA in Mesenteric Ischemia: Part 2, Normal Findings and Complications After Surgical and Endovascular Treatment

OBJECTIVE

A number of surgical and endovascular options exist for the treatment of acute and chronic mesenteric ischemia. Both surgical and endovascular treatments necessitate close clinical and imaging follow-up because the consequences of acute occlusions can be catastrophic. MDCT angiography (CTA) and contrast-enhanced MR angiography (MRA) are the preferred imaging techniques in this setting.

CONCLUSION

We review the appearance of the normal and complicated surgical and endovascular treatment on CTA and MRA.

Evaluation of the Effect of Endovascular Options on Infrarenal Abdominal Aortic Aneurysm Repair

Endovascular devices designed to exclude flow to infrarenal abdominal aortic aneurysms (AAA) were approved by the Food and Drug Administration in the United States in 1999. This action allowed widespread use of this technology for AAA exclusion. The purpose of this report is to examine trends for use of these modalities, rates of rupture of AAA, and to compare results of open AAA repair with endovascular repair. Results were collected for all hospitals, except for Veterans Administration hospitals, by a state-wide repository. Data for the years 1996 through 1998 and 2001 through 2002 were evaluated, and data from 1999 through 2000 were excluded because no separate codes were available to distinguish between open and endovascular repair. The information gathered is based on the All Patient Refined Diagnostic Related Group (APR-DRG®; 3M, St. Paul, MN). An average of 718 open, elective AAA was performed between 1996 and 1998. This dropped to 503 open repairs from 2001 to 2002 ( P < 0.005). During that same interval, 308 endovascular elective AAA repairs were performed, therefore the total rate of elective repair increased by 100. The average rate of ruptured AAA repairs from 1996 to 1998 was 121 per year, and this dropped to 89 from 2001 to 2002 ( P < 0.005). The mortality of open AAA repair during the 1996 to 1998 and 2001 to 2002 intervals was unchanged (4.7%). Mortality from endovascular AAA repair between 2001 and 2002 was 1.9 per cent ( P = 0.003). Major morbidity was 14.5 per cent for open, elective AAA repair and 6.3 per cent for endovascular elective repair from 2001 to 2002 ( P < 0.001). These data suggest that the advent of endovascular AAA repair has contributed to a reduction in the rate of ruptured AAA repairs, an increase in total procedures performed, and a significant decrease in perioperative deaths and major complications when compared with open AAA repair.

Endoscopic versus open saphenous vein harvest for femoral to below the knee arterial bypass using saphenous vein graft

BACKGROUND

Although the use of endoscopic vein harvest (EVH) in coronary artery bypass grafting is accepted, few studies have documented the implementation of EVH in peripheral vascular disease surgery. We hypothesized that EVH improves outcomes compared with open vein harvest (OVH) in patients undergoing femoral to below the knee arterial bypass surgery.

METHODS

The charts of 144 consecutive patients undergoing infrainguinal bypass surgery over the course of 27 months were reviewed. A femoral to below the knee arterial bypass with saphenous vein was done in 88 patients (29 had EVH, 59 had OVH). The preoperative characteristics evaluated were age, gender, renal function, history of diabetes, hypertension, tobacco use, and previous infrainguinal bypass surgery on the affected side. End points included wound complications, length of hospital stay, operative time, angiographic and operative interventions for graft occlusion, patency rates, limb salvage, acute renal failure, myocardial infarction, and death.

RESULTS

Patient characteristics and demographics were similar in the EVH and OVH groups. No operative intervention for occlusion was required in the EVH group (0/29) compared with 13.4% in the OVH group (8/59) (P = .03). At the mean follow-up time of 21 months, primary patency rate was 92.8% in the EVH group and 80.6% in the OVH group (P = .12). No significant differences were found between the EVH and OVH groups in postoperative complications, length of hospital stay, operative time, patency rates, limb salvage, and death.

CONCLUSION

Despite our initial concerns of damaging the venous conduit with a minimally invasive approach to saphenous vein harvest, EVH in our experience has resulted in a trend toward improved patency rates and decreased infectious wound complications while affording the benefit of improved cosmesis. An endoscopic approach results in smaller incisions, decreased interventions for occlusion, and improved outcomes compared with OVH. EVH is the procedure of choice for harvesting saphenous vein for femoral to below the knee arterial bypass surgery.

Evaluation of the effect of endovascular options on infrarenal abdominal aortic aneurysm repair

Endovascular devices designed to exclude flow to infrarenal abdominal aortic aneurysms (AAA) were approved by the Food and Drug Administration in the United States in 1999. This action allowed widespread use of this technology for AAA exclusion. The purpose of this report is to examine trends for use of these modalities, rates of rupture of AAA, and to compare results of open AAA repair with endovascular repair. Results were collected for all hospitals, except for Veterans Administration hospitals, by a state-wide repository. Data for the years 1996 through 1998 and 2001 through 2002 were evaluated, and data from 1999 through 2000 were excluded because no separate codes were available to distinguish between open and endovascular repair. The information gathered is based on the All Patient Refined Diagnostic Related Group (APRDRG; 3M, St. Paul, MN). An average of 718 open, elective AAA was performed between 1996 and 1998. This dropped to 503 open repairs from 2001 to 2002 (P < 0.005). During that same interval, 308 endovascular elective AAA repairs were performed, therefore the total rate of elective repair increased by 100. The average rate of ruptured AAA repairs from 1996 to 1998 was 121 per year, and this dropped to 89 from 2001 to 2002 (P < 0.005). The mortality of open AAA repair during the 1996 to 1998 and 2001 to 2002 intervals was unchanged (4.7%). Mortality from endovascular AAA repair between 2001 and 2002 was 1.9 per cent (P = 0.003). Major morbidity was 14.5 per cent for open, elective AAA repair and 6.3 per cent for endovascular elective repair from 2001 to 2002 (P < 0.001). These data suggest that the advent of endovascular AAA repair has contributed to a reduction in the rate of ruptured AAA repairs, an increase in total procedures performed, and a significant decrease in perioperative deaths and major complications when compared with open AAA repair.

Thoracic aortic endografting is the treatment of choice for elderly patients with thoracic aortic disease

OBJECTIVE

To assess the effect of age on outcomes following thoracic aortic endografting.

SUMMARY BACKGROUND DATA

Endograft therapy for thoracic aortic disease is rapidly evolving. This therapy is less invasive, and elderly patients with significant medical comorbidities are more frequently referred for endografting. We hypothesized that elderly patients over the age of 75 have worse outcomes after thoracic endografting than patients under the age of 75.

METHODS

We retrospectively reviewed the charts of the first 42 patients who underwent endografting for thoracic aortic pathology. Charts were reviewed for demographics, comorbid conditions, perioperative complications and death, endoleaks, and results at 3, 6, and 12 months. Preexisting medical conditions were also evaluated to determine if any patient characteristics were associated with adverse outcomes. Perioperative morbidity included cardiac, pulmonary, renal, hemorrhagic, and neurologic (stroke and spinal cord injury) complications.

RESULTS

Twenty-four patients were under the age of 75, and 18 patients were 75 or older. Baseline demographics and comorbidities were similar between the 2 groups. There were no differences in operative time, length of stay, perioperative mortality, or the incidence of significant complications between the 2 age groups. Gender, however, was associated with a statistically significant difference between the occurrence of complications, with more women experiencing complications than men (P = 0.026, relative risk = 2.36). One patient (age >75 years) in the entire cohort of 42 (2.4%) suffered a spinal cord injury. At 3 months, endoleaks were more common in the older age group (P = 0.059).

CONCLUSION

Endograft therapy for thoracic aortic disease can be performed safely in elderly patients with no significant increase in perioperative morbidity or mortality compared with younger patients. Female gender is associated with a higher likelihood of perioperative complications, regardless of age. The overall incidence of spinal cord injury is very low. Endograft therapy, when anatomically possible, is the treatment of choice for thoracic aortic disease in elderly patients.

Delayed calf muscle phosphocreatine recovery after exercise identifies peripheral arterial disease

OBJECTIVES

In this study we intend to characterize phosphocreatine (PCr) recovery kinetics with phosphorus-31 ((31)P) magnetic resonance spectroscopy in symptomatic peripheral arterial disease (PAD) patients compared with control subjects and determine the diagnostic value and reproducibility of this parameter.

BACKGROUND

Due to the inconsistent relationship between flow and function in PAD, novel techniques focused on the end-organ are needed to assess disease severity and measure therapeutic response.

METHODS

Fourteen normal subjects (5 men, age 45 +/- 14 years) and 20 patients with mild-to-moderate symptomatic PAD (12 men, age 67 +/- 10 years, mean ankle brachial index 0.62 +/- 0.13) were studied. Subjects exercised one leg to exhaustion while supine in a 1.5-T magnetic resonance scanner using a custom-built plantar flexion device. Surface coil-localized, free induction decay acquisition localized to the mid-calf was used. Each 31P spectrum consisted of 25 signal averages at a repetition time of 550 ms. The PCr recovery time constant was calculated by monoexponential fit of PCr versus time, beginning at exercise completion.

RESULTS

Median exercise time was 195.0 s in normal subjects and 162.5 s in PAD patients (p = 0.06). Despite shorter exercise times in patients, the median recovery time constant of PCr was 34.7 s in normal subjects and 91.0 s in PAD patients. Area under the receiver-operating characteristic curve was 0.925 +/- 0.045. Test-retest reliability was excellent.

CONCLUSIONS

The PCr recovery time constant is prolonged in patients with symptomatic PAD compared with normal subjects. The method is reproducible and may be useful in the identification of disease. Further study of this parameter's ability to track response to therapy as well as its prognostic capability is warranted.

Comparison of Multistation MR Angiography with Integrated Parallel Acquisition Technique versus Conventional Technique with a Dedicated Phased-array Coil System in Peripheral Vascular Disease

PURPOSE

To assess the impact of integrated parallel acquisition technique (iPAT) on signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), venous contamination, and overall image interpretability for peripheral magnetic resonance (MR) angiography with use of a dedicated phased-array coil system.

MATERIALS AND METHODS

Three-dimensional contrast material-enhanced conventional MR angiography and iPAT peripheral MR angiography was performed at three stations (pelvis, thigh, calf) in 38 consecutive patients on a 1.5-T high-performance cardiovascular system (conventional MR angiography, n=19; iPAT MR angiography, n=19). A total of 29 vessel segments per patient were analyzed. For each segment, arterial, muscle, and background signal were measured; SNR and CNR were calculated; and repeated-measures analysis of variance was performed. For each of the three stations, the degree of venous contamination and the overall confidence of interpretability were analyzed with use of ordinal logistic regression analysis accounting for correlated outcome data.

RESULTS

A total of 1,018 vessel segments were available for analysis (477 with conventional MR angiography, 541 with iPAT MR angiography). Compared with conventional MR angiography, iPAT MR angiography resulted in decreased SNR and CNR in the pelvis and thigh stations but no change in the calf station. The difference in the pelvis was statistically significant (P<.007 for SNR and P<0.01 for CNR). Venous contamination in the calf station was significantly less on iPAT MR angiography (P<.003), with no significant differences in the other stations. The overall confidence of interpretability with iPAT MR angiography was significantly better on the lower station (P<.008).

CONCLUSIONS

iPAT MR angiography leads to reduced SNR and CNR in the pelvis and thigh, but this does not affect interpretability of images obtained at these stations. The temporal gain results in significantly increased interpretability as a result of less venous contamination in the calf station. iPAT MR angiography is superior to conventional MR angiography for peripheral imaging.

Remediation of low ABSITE scores

PURPOSE

In 2000, a program was initiated to improve American Board of Surgery In-Training Exam (ABSITE) scores below the 40th percentile (PGY-1 and -2) and the 30th percentile (PGY-3 and -5) for categorical residents. The goal of this program is to maintain scores above this standard.

METHODS

One faculty member was designated to meet with each resident with ABSITE scores below the standard described above. In April, individual study plans were designed with each resident, which emphasized practice questions and strategic planning for study, and the ABSITE test structure and results were reviewed. Two subsequent meetings were held between November and December to monitor progress. Emphasis was placed on minimizing the stigma of poor scores and on maximizing the efficiency of study time. If the resident scored above-standard that year, further support was not required.

RESULTS

From 2000 to 2004, 12 (9.5%) ABSITE scores were below-standard, which resulted in 8 (20.5%) residents receiving program support 9 times. All but 1 program encounter resulted in above-standard scores the following year (improvement range, 16 to 65 percentile points; average, 34 points). Two residents had recurrent below-standard scores in subsequent years despite above-standard scores immediately after the program. One resident did not participate in the program, despite it being designated as mandatory. During the same interval, the ABSITE scores of residents not involved in the program decreased by an average of 3.7 percentile points per examination (improved scores 31 times; 39.2%, range 1 to 46, average 13.5, worse scores 45 times; 57%, range 1 to 65, average 15.2, and no change 3 times, 3.8%).

CONCLUSIONS

An individualized program that minimizes the stigma of poor test results, the time commitment required by the residents, and maximizes the benefits of a question-based study system and the knowledge of approach to the ABSITE resulted in significant improvements in scores the next year. However, maintenance of these results needs continued evaluation because 3 residents had recurrent poor scores in subsequent years.

Subfascial endoscopic perforating vein surgery (SEPS) for the treatment of venous ulcers

Lower extremity ulcerations that result from venous hypertension are a significant cause of disability in Western nations. Venous ulcers, highly related to lower extremity venous valvular incompetence and post-thrombotic syndrome, demonstrate a protracted course of healing with a high recurrence rate when managed conservatively. Effective treatment includes correcting the elevated lower extremity venous pressure using non-invasive (compression therapy) or invasive modalities (removal or correction of incompetent venous segments, most commonly the greater saphenous vein). Minimally invasive subfascial endoscopic perforating vein surgery, performed on an outpatient basis, allows ligation of incompetent Cockett perforating veins. Venous ulcer healing rates of 88% and infrequent wound complications have been reported using this technique. Using 5-mm cameras and trocars that are available for other endoscopic surgeries could further improve this technique; creating ports smaller than the traditional 15-mm incisions would subsequently reduce tissue disruption. In addition, the etiology of recurrent ulceration and the failure of the primary ulcer to heal are not completely understood. If these poor outcomes can be further defined, even higher rates of wound healing may be attained using this procedure. Significant efforts have been devoted to elucidating the exact mechanism of skin breakdown from venous hypertension but the pathophysiology of this process is still not understood.

Carotid endarterectomy: update on the gold standard treatment for carotid stenosis

Many prospective, randomized clinical trials evaluating the safety and efficacy of carotid endarterectomy (CEA) versus medical management in the prevention of ischemic stroke were performed in the 1990s. Clinical trials are underway that will compare CEA outcomes to carotid stenting; however, relatively few studies have examined the outcomes of modern CEA. The purpose of this report is to examine current outcomes of CEA and evaluate hospital costs and length of stay. Statewide results were collected for all hospitals, except Veterans Administration hospitals, by Virginia Health Information (VHI). Data for the years 1997-2001 were evaluated, and data were based on the All Patient Refined Diagnostic Related Group (APR-DRG; 3M Company). A total of 14,095 CEAs were performed in a 5-year period. The mortality of patients undergoing CEA was 0.5 per cent. The stroke rate was 1 per cent overall and decreased each year of the study. Mean and median lengths of hospital stay were 3 and 2 days, respectively. Length of stay decreased over the course of this study. Mean and median hospital costs were 14,331 dollars and 11,268 dollars. Higher rates of mortality and stroke and higher costs were observed at low-volume hospitals. The need for CEA is substantial. CEA is safe and inexpensive. The data presented here demonstrates continued refinement in CEA, leading to a very low rate of perioperative adverse events, declining lengths of stay, and low hospital costs.

Carotid Endarterectomy: Update on the Gold Standard Treatment for Carotid Stenosis

Many prospective, randomized clinical trials evaluating the safety and efficacy of carotid endarterectomy (CEA) versus medical management in the prevention of ischemic stroke were performed in the 1990s. Clinical trials are underway that will compare CEA outcomes to carotid stenting; however, relatively few studies have examined the outcomes of modern CEA. The purpose of this report is to examine current outcomes of CEA and evaluate hospital costs and length of stay. Statewide results were collected for all hospitals, except Veterans Administration hospitals, by Virginia Health Information (VHI). Data for the years 1997–2001 were evaluated, and data were based on the All Patient Refined Diagnostic Related Group (APR-DRG; 3M Company). A total of 14,095 CEAs were performed in a 5-year period. The mortality of patients undergoing CEA was 0.5 per cent. The stroke rate was 1 per cent overall and decreased each year of the study. Mean and median lengths of hospital stay were 3 and 2 days, respectively. Length of stay decreased over the course of this study. Mean and median hospital costs were $14,331 and $11,268. Higher rates of mortality and stroke and higher costs were observed at low-volume hospitals. The need for CEA is substantial. CEA is safe and inexpensive. The data presented here demonstrates continued refinement in CEA, leading to a very low rate of perioperative adverse events, declining lengths of stay, and low hospital costs.

Surgical revascularization in the presence of a preserved primitive carotid-basilar communication

Anomalous arteries that connect the anterior and posterior cranial arterial systems are unusual variants that can severely alter normal patterns of cerebral blood flow. Persistent trigeminal, hypoglossal, otic, and proatlantal arteries have been described. This report illustrates the technical aspects of carotid endarterectomy with an ipsilateral preserved primitive carotid-basilar communication. Identification of the internal carotid and hypoglossal arteries, maintenance of cerebral perfusion, arteriotomy closure, preoperative imaging, the use of shunts, and reconstruction strategy are discussed. Preoperative angiography and detailed, individualized surgical strategy should be used to ensure a successful endarterectomy in patients with preserved primitive carotid-basilar communications.

Examination of sex as an independent risk factor for adverse events after carotid endarterectomy

BACKGROUND

The incidence of adverse events after carotid endarterectomy (CEA) for women compared with men is controversial. This report compares the incidence of perioperative stroke and death in men and women by examining the effect of comorbidities and hospital setting on CEA outcomes.

METHODS

All CEAs performed in non-Federal acute-care Virginia hospitals between 1997 and 2001 were reviewed. Patient demographics, comorbidities, and hospital characteristics were compared for possible relationships to perioperative adverse events.

RESULTS

A total of 14,095 CEAs were performed in 34 urban and 28 rural hospitals (9 high-volume and 53 low-volume hospitals); 42% were performed on women, and 58% were performed on men. Women experienced a significantly higher stroke rate (1.23%) than men (0.87%; P = .04) with bivariate analysis. However, logistic regression analysis of comorbidities and hospital settings demonstrated that sex was actually not independently related to adverse outcomes in CEA ( P = .08). Preoperative neurologic symptoms could not be evaluated as risk factors for adverse events. Acute coronary ischemia, history of arrhythmia, end-stage renal disease, nonwhite race, advanced age, and low hospital volume were all significantly related to mortality. History of arrhythmia was the only factor that was significantly related to the incidence of stroke.

CONCLUSIONS

Logistic regression analysis of comorbidities and hospital setting indicated that female sex is not independently associated with higher mortality or a higher stroke rate during CEA. These data indicate that patients with carotid stenosis frequently have multiple medical problems that need to be carefully examined and controlled before any single patient or hospital factor is designated as significantly related to adverse outcomes.

Subintimal Arterial Flossing with Antegrade–Retrograde Intervention (SAFARI) for Subintimal Recanalization to Treat Chronic Critical Limb Ischemia

PURPOSE

To describe the technique of subintimal arterial flossing with antegrade-retrograde intervention (SAFARI) to improve technical success for the performance of subintimal recanalization when there is failure to reenter the distal true lumen or when there is a limited segment of patent distal target artery available for reentry.

MATERIALS AND METHODS

Subintimal recanalization was attempted in an antegrade direction in all patients. If reentry into the distal true lumen was unsuccessful or a short segment of target artery was present, retrograde access was obtained in the distal target artery (popliteal, anterior tibial/dorsalis pedis, or posterior tibial) and a retrograde subintimal channel was created. A guide wire was used to connect the retrograde and antegrade subintimal channels simultaneously to create a "flossing" guide wire. The subintimal tract was dilated with balloon angioplasty with or without stent implantation. Limb salvage, amputation-free survival, and survival rates over time were determined.

RESULTS

The SAFARI technique resulted in successful subintimal recanalization creating straight-line flow to the foot in all 21 limbs in 20 patients in which the technique was attempted. Antegrade-retrograde access was performed with the femoral artery and the following vessels: popliteal, n = 11; anterior tibial/dorsalis pedis, n = 10; and posterior tibial, n = 2 (two limbs involved multiple accesses). All procedures were successful. The limb salvage rate with SAFARI was 90% (95% CI, 74%-100%) at 6 months.

CONCLUSIONS

The SAFARI technique can be useful for completing subintimal recanalization when there is failure to reenter the distal true lumen from an antegrade approach or when there is limited distal target artery available for reentry. The SAFARI technique improves technical success in the performance of subintimal recanalization. Limb salvage rates are comparable to those with antegrade subintimal recanalization.

Percutaneous Intentional Extraluminal Recanalization in Patients with Chronic Critical Limb Ischemia

PURPOSE

To review percutaneous intentional extraluminal recanalization (PIER) for treatment of patients who are poor candidates for infrainguinal arterial bypass surgery (IABS) and have arterial occlusions and chronic critical limb ischemia (CCLI).

MATERIALS AND METHODS

Patients with CCLI who were poor candidates for IABS were candidates for PIER. PIER was performed to create continuous arterial flow to the foot for limb salvage. PIER was attempted in 40 patients (22 men, 18 women; median age, 69 years; age range, 44-87 years). Of these patients, 24 (60%) had diabetes, 17 (42%) had renal disease, and 26 (66%) had coronary artery disease. Wound healing was evaluated at follow-up. Kaplan-Meier curves were constructed to evaluate limb salvage, survival, and amputation-free survival.

RESULTS

Fifty procedures were attempted in 44 limbs. Tissue loss was present in 40 (91%) limbs, and rest pain was present in four (9%); technical success occurred in 38 (86%). Thirty-seven (84%) of 44 limbs treated with PIER involved tibial vessels (tibial vessels only, n = 15; tibial and superior femoral artery [SFA] and/or popliteal vessels, n = 22). Sixty-six infrainguinal arterial vessel segments (SFA, n = 29; tibial, n = 37) in 38 limbs (1.7 segments per limb) were successfully treated with PIER. Thirty-five (95%) of 37 tibial occlusions and 24 (83%) of 29 SFA and/or popliteal occlusions were longer than 10 cm. Median run-off scores were 5.3 (range, 3-8) and 6.6 (range, 3-9) for patients with tibial occlusions and SFA and/or popliteal occlusions, respectively, as scored with modified Rutherford weighting of run-off arteries. Median follow-up was 7.8 months (range, 1-24 months). Twelve months after PIER, Kaplan-Meier analysis showed limb salvage rate was 66%, survival rate was 71%, and amputation-free survival rate was 48% in these patients. The 30-day mortality rate was 2.5%. Major complications occurred in four (10%) patients, and minor complications occurred in an additional four (10%).

CONCLUSION

PIER is a useful percutaneous technique for limb salvage in patients with CCLI.

Subintimal Recanalization is Safe and Effective in Treating Chronic Critical Limb Ischemia in Selected Patients

Subintimal recanalization is a percutaneous technique that allows revascularization in patients with limb-threatening ischemia. It was first described by Bolia (Cardiovasc Intervent Radiol 13;357–63:1990) but has not gained widespread use in the United States. Twenty-five patients with 32 threatened limbs were referred from a single surgeon's practice over a 23-month period. All patients were either high-risk surgical patients, due to severe medical comorbidities, or not surgical candidates due to poor target vessels, lack of appropriate conduit, or failed previous surgical revascularizations. The average age of patients was 69. There were 15 men and 10 women treated. Subintimal recanalization was immediately successful in 30 limbs. One peri-procedural death occurred, although this patient underwent a surgical bypass graft procedure in the same hospitalization. Three significant complications occurred (myocardial infarction, ventricular arrhythmia, and gastrointestinal hemorrhage). Primary patency is 83 per cent. Secondary patency is 90 per cent. Limb salvage rate is 88 per cent. Mean follow-up period is 10 months. Eight patients died in the follow-up period due to unrelated causes.

Subintimal recanalization is safe and effective in treating chronic critical limb ischemia in selected patients

Subintimal recanalization is a percutaneous technique that allows revascularization in patients with limb-threatening ischemia. It was first described by Bolia (Cardiovasc Intervent Radiol 13;357-63:1990) but has not gained widespread use in the United States. Twenty-five patients with 32 threatened limbs were referred from a single surgeon's practice over a 23-month period. All patients were either high-risk surgical patients, due to severe medical comorbidities, or not surgical candidates due to poor target vessels, lack of appropriate conduit, or failed previous surgical revascularizations. The average age of patients was 69. There were 15 men and 10 women treated. Subintimal recanalization was immediately successful in 30 limbs. One peri-procedural death occurred, although this patient underwent a surgical bypass graft procedure in the same hospitalization. Three significant complications occurred (myocardial infarction, ventricular arrhythmia, and gastrointestinal hemorrhage). Primary patency is 83 per cent. Secondary patency is 90 per cent. Limb salvage rate is 88 per cent. Mean follow-up period is 10 months. Eight patients died in the follow-up period due to unrelated causes.

Simultaneous Antegrade and Retrograde Access for Subintimal Recanalization of Peripheral Arterial Occlusion

Subintimal recanalization can be a useful procedure in selected patients with severe peripheral vascular disease with tissue loss or rest pain and limited surgical bypass options. Technical failure occurs in approximately 20% of patient who undergo percutaneous intentional extraluminal recanalization due to inability to reenter the distal true lumen. A technique to improve technical success when performing subintimal recanalization when there is failure to reenter the distal true lumen or possibly when there is a limited segment of patent distal target vessel for reentry is proposed. Further evaluation of this technique is necessary to confirm its safety and determine its technical and clinical success.