Thomas S. Riles

2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS Guideline on the Management of Patients With Extracranial Carotid and Vertebral Artery Disease

Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .491 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .493 2. Recommendations for Duplex Ultrasonography to Evaluate Asymptomatic Patients With Known or Suspected Carotid Stenosis . . . . . . . . . . . . . . . . .494 3. Recommendations for Diagnostic Testing in Patients With Symptoms or Signs of Extracranial Carotid Artery Disease . . . . . . . . . . . . .495 4. Recommendations for the Treatment of Hypertension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .495 5. Recommendation for Cessation of Tobacco Smoking. . . . . . . . . . . . . . . . . . . . . . . . . . .495 6. Recommendations for Control of Hyperlipidemia. . . . . . . . . . . . . . . . . . . . . . . . . . . . .496 7. Recommendations for Management of Diabetes Mellitus in Patients With Atherosclerosis of the Extracranial Carotid or Vertebral Arteries. . . . . . . . . . . . …

The cause of perioperative stroke after carotid endarterectomy

PURPOSE The purpose of this study was to examine the cause of perioperative stroke after carotid endarterectomy. METHODS The records of 2365 patients undergoing 3062 carotid endarterectomies from 1965 through 1991 were reviewed. Sixty-six (2.2%) operations were associated with a perioperative stroke. The mechanism of stroke was determined in 63 of 66 cases. Patient risk factors and surgeon-dependent factors were analyzed. RESULTS More than 20 different mechanisms of perioperative stroke were identified, but most could be grouped into broad categories of ischemia during carotid artery clamping (n = 10), postoperative thrombosis and embolism (n = 25), intracerebral hemorrhage (n = 12), strokes from other mechanisms associated with the surgery (n = 8), and stroke unrelated to the reconstructed artery (n = 8). Dividing the operative experience approximately into thirds, during the years 1965 to 1979, 1980 to 1985, and 1986 to 1991 the perioperative stroke rates were 2.7%, 2.2%, and 1.5%, respectively. This, in part, is associated with a better selection of patients (more symptom free, fewer with neurologic deficits). There has been a notable decrease in perioperative stroke caused by ischemia during clamping and intracerebral hemorrhage, but postoperative thrombosis and embolism remain the major cause of neurologic complications. CONCLUSIONS Although patient selection seems to play a role, most perioperative strokes were due to technical errors made during carotid endarterectomy or reconstruction and were preventable.

Analysis of risk factors for abdominal aortic aneurysm in a cohort of more than 3 million individuals.

BACKGROUND Abdominal aortic aneurysm (AAA) disease is an insidious condition with an 85% chance of death after rupture. Ultrasound screening can reduce mortality, but its use is advocated only for a limited subset of the population at risk. METHODS We used data from a retrospective cohort of 3.1 million patients who completed a medical and lifestyle questionnaire and were evaluated by ultrasound imaging for the presence of AAA by Life Line Screening in 2003 to 2008. Risk factors associated with AAA were identified using multivariable logistic regression analysis. RESULTS We observed a positive association with increasing years of smoking and cigarettes smoked and a negative association with smoking cessation. Excess weight was associated with increased risk, whereas exercise and consumption of nuts, vegetables, and fruits were associated with reduced risk. Blacks, Hispanics, and Asians had lower risk of AAA than whites and Native Americans. Well-known risk factors were reaffirmed, including male gender, age, family history, and cardiovascular disease. A predictive scoring system was created that identifies aneurysms more efficiently than current criteria and includes women, nonsmokers, and individuals aged <65 years. Using this model on national statistics of risk factors prevalence, we estimated 1.1 million AAAs in the United States, of which 569,000 are among women, nonsmokers, and individuals aged <65 years. CONCLUSIONS Smoking cessation and a healthy lifestyle are associated with lower risk of AAA. We estimated that about half of the patients with AAA disease are not eligible for screening under current guidelines. We have created a high-yield screening algorithm that expands the target population for screening by including at-risk individuals not identified with existing screening criteria.

The importance of hemorrhage in the relationship between gross morphologic characteristics and cerebral symptoms in 376 carotid artery plaques.

In a prospective study 376 carotid artery plaques (275 symptomatic, 101 asymptomatic) were obtained from endarterectomies (184 unilateral and 96 bilateral) in 280 patients. The gross morphologic features of each plaque were noted at surgery and, together with the patients clinical history, stored in computer memory. These data were analyzed in order to investigate the relationship of gross morphologic plaque characteristics with both the presence of cerebral symptoms and the degree of stenosis associated with the plaque. Ulceration was the most frequently observed of the five major gross plaque morphologic characteristics (46.0% of all plaques), but only intramural hemorrhage (30.6% of all plaques) was significantly more common in all symptomatic compared with all asymptomatic plaques (p < 0.02). Hemorrhage was also the only gross characteristic significantly more common in focal symptomatic plaques when compared with either asymptomatic plaques (p < 0.05) or nonfocal symptomatic plaques (p < 0.01). When all the plaques were divided into three broad degrees of stenosis groups (0–39%, 40–69%, 70–99%) on the basis of angiographic data, only hemorrhage showed a significant correlation in incidence with increased degree of plaque stenosis, both when all plaques were considered (p < 0.001) and when only symptomatic plaques were examined (p < 0.001). The results indicate that intramural hemorrhage is the only carotid plaque gross morphologic characteristic significantly more frequent in symptomatic compared with asymptomatic plaques and the only characteristic significantly correlated with increased plaque size. These findings indicate that factors other than plaque ulceration and intraluminal thrombus play an important role in carotid plaque related cerebral symptoms. The data also raise questions concerning the unequivocal value of anticoagulant therapy in carotid artery disease, especially in highly stenotic lesions.

The carotid bifurcation plaque: pathologic findings associated with cerebral ischemia.

Embolization from or decreased flow through cervical carotid and vertebral arteries causes ischemic stroke syndromes. Specific pathologic findings were studied in SO symptomatic patients who underwent 69 carotid endarterectomies. Detailed analyses of their carotid plaques included correlations between photographs of gross specimens, microscopic findings, angiograms, preoperative symptoms and long-term postoperative follow up. Carotid plaques were primarily fibrous with significant (> 70%) stenoses encountered in 70% of the arteries. Stenoses were due to simple fibrous thickening in only 20%; the remainder due to intraplaque hemorrhage, atheromatous debris and, least often, luminal thrombus with or without ulceration. Intramural hemorrhage was frequent in plaques associated with focal neurologic symptoms and may have preceded localized collections of atheromatous debris. Ulceration occurred in 1/3 of all plaques, symptomatic or not. It is concluded that the carotid plaques start as fibrointimal thickening evolving to symptomatic stages by the occurrence of one or more of a number of pathologic changes, intraplaque hemorrhage being prominent. A single rational therapeutic regimen seems impossible until patients can be classified according to their pathologic changes diagnosed non-invasively.

Suggested standards for reports dealing with cerebrovascular disease

The evaluation of clinical reports on vascular disease is often made difficult by variations in descriptive terms, clinical classification, and outcome criteria. In 1983 the Joint Council of the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery created the Ad Hoc Committee on Reporting Standards to address these problems and recommend solutions. Some general problems were addressed in the initial report dealing with lower extremity ischemia. This article concerns clinical standards for reports dealing with cerebrovascular disease, suggests a scheme for clinical classification, and recommends standardized reporting practices for grading risk factors, angiographic and other diagnostic findings, and the results and complications of therapeutic intervention.

The value of silent myocardial ischemia monitoring in the prediction of perioperative myocardial infarction in patients undergoing peripheral vascular surgery

Real-time electrocardiographic monitoring for silent myocardial ischemia was performed on 200 patients undergoing peripheral vascular surgery to try to better define those at high risk of perioperative myocardial infarction. The patients were divided into those undergoing abdominal aortic aneurysm or lower extremity revascularization procedures (group I, n = 120) and those undergoing carotid artery endarterectomy (group II, n = 80). Silent ischemia was detected during the preoperative, intraoperative, or post-operative periods in 60.8% of group I and 67.5% of group II patients. Six group I and three group II patients suffered an acute perioperative myocardial infarction with two cardiac deaths. In both groups I and II a variety of parameters based on monitoring of silent myocardial ischemia were compared between the subgroups of patients who had myocardial infarction and those who did not. The results show that in both groups there was a significantly (p less than or equal to 0.05) greater total duration of perioperative ischemic time, total number of perioperative ischemic episodes, and total duration of perioperative ischemic time as a percent of total monitoring time in patients who suffered a perioperative myocardial infarction compared to those who did not. Multivariate logistic regression analysis of preoperative characteristics in all 200 patients showed the occurrence of preoperative silent myocardial ischemia and angina at rest to be the only significant predictors of perioperative myocardial infarction. Thus perioperative monitoring for silent myocardial ischemia might noninvasively identify those patients undergoing peripheral vascular surgery who are at increased risk for perioperative myocardial infarction, permitting implementation of timely preventive measures in selected patients.

Beta blockade to decrease silent myocardial ischemia during peripheral vascular surgery

Abstract The incidence and duration of intraoperative silent myocardial ischemia have been shown to be significantly correlated with the incidence of perioperative myocardial infarction in patients undergoing peripheral vascular surgery. To assess the effectiveness of intraoperative beta blockade in limiting such silent myocardial ischemia, a group of 48 patients was treated with oral metoprolol immediately prior to peripheral vascular surgery. The total duration of intraoperative silent myocardial ischemia, the percentage of intraoperative time silent myocardial ischemia was present, the number of intraoperative episodes of silent myocardial ischemia, and the intraoperative heart rate in the treated patients were compared with those in 152 similar but untreated peripheral vascular surgery patients. The patients treated with oral metoprolol had significantly less intraoperative silent ischemia with respect to relative duration and frequency of episodes, a significantly lower intraoperative heart rate, and less intraoperative silent myocardial ischemia in terms of total absolute duration. These results suggest that beta-adrenergic activation may play a major role in the pathogenesis of silent myocardial ischemia during peripheral vascular surgery.

The value of radionuclide angiography as a predictor of perioperative myocardial infarction in patients undergoing abdominal aortic aneurysm resection

To define the group of patients at high risk for myocardial infarction (MI) and death associated with abdominal aortic aneurysm repair, resting gated blood pool studies were obtained on 50 such aneurysm patients preoperatively. The results indicated that three groups could be distinguished among these patients by cardiac ejection fraction. Group I (n = 25) had preoperative ejection fractions ranging from 56% to 85%. None of the patients in group I suffered an acute perioperative MI. Group II (n = 20) comprised patients with ejection fractions ranging from 36% to 55%. There was a 20% incidence of MI in group II but no cardiac deaths. Group III included five patients with ejection fractions ranging from 27% to 35%. There was an 80% incidence of perioperative MI in these patients, with one cardiac death and one cardiac arrest. All perioperative MIs occurred within the first 48 hours after surgery. In addition there was a 50% incidence of perioperative MI among all those patients who were 80 years of age or older. These results indicate guidelines for the management of patients undergoing abdominal aortic aneurysm repair based on their preoperative ejection fraction. The data further suggest that the noninvasive gated blood pool method of determining ejection fraction may serve a more broadly useful function in helping to determine which of those patients about to undergo major surgical procedures are at high risk for perioperative MI.

Comparison of magnetic resonance angiography, conventional angiography, and duplex scanning.

Background and Purpose To determine the accuracy of magnetic resonance angiography in assessing patients with cerebrovascular disease, we performed a study comparing the results of conventional cerebral angiography, duplex scanning, and magnetic resonance angiography. Methods From 42 patients, a total of 25 carotid arteries were evaluated by all three techniques. The studies were independently read and sorted into five categories according to the degree of stenosis: 0–15%, normal; 16–49%, mild; 50–79%, moderate; 80–99%, severe; and totally occluded. Results Magnetic resonance angiography correlated exactly with conventional angiography in 39 arteries (52%); duplex scanning correlated with conventional angiography in 49 cases (65%). Compared with conventional angiography, both magnetic resonance angiography and duplex scanning tended to overread the degree of stenosis. The most critical errors associated with magnetic resonance angiography were three readings of total occlusion in vessels found to be patent on conventional angiograms. Conclusions Although magnetic resonance angiography offers great hope of providing high-quality imaging of the carotid artery with no risk and at less cost, data from this study suggest that misreading the degree of stenosis, or misinterpreting a stenosis for an occlusion, could lead to errors in clinical decisions. Guidelines for use of magnetic resonance angiography in a clinical setting are offered.