Cognitive function in people with and without freezing of gait in Parkinson’s disease

Freezing of gait (FOG) is common in people with Parkinson’s disease (PD) which is extremely debilitating. One hypothesis for the cause of FOG episodes is impaired cognitive control, however, this is still in debate in the literature. We aimed to assess a comprehensive range of cognitive tests in older adults and people with Parkinson’s with and without FOG and associate FOG severity with cognitive performance. A total of 227 participants took part in the study which included 80 healthy older adults, 81 people with PD who did not have FOG and 66 people with PD and FOG. A comprehensive battery of neuropsychological assessments tested cognitive domains of global cognition, executive function/attention, working memory, and visuospatial function. The severity of FOG was assessed using the new FOG questionnaire and an objective FOG severity score. Cognitive performance was compared between groups using an ANCOVA adjusting for age, gender, years of education and disease severity. Correlations between cognitive performance and FOG severity were analyzed using partial correlations. Cognitive differences were observed between older adults and PD for domains of global cognition, executive function/attention, and working memory. Between those with and without FOG, there were differences for global cognition and executive function/attention, but these differences disappeared when adjusting for covariates. There were no associations between FOG severity and cognitive performance. This study identified no significant difference in cognition between those with and without FOG when adjusting for covariates, particularly disease severity. This may demonstrate that complex rehabilitation programs may be undertaken in those with FOG

Digital subtraction angiography: A review of cardiac applications

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25579/1/0000123.pd

Anticoagulation for cardioversion of atrial fibrillation

A trial fibrillation (AF) is a common arrhythmia associated with a broad spectrum of underlying diseases that include systemic hypertension, rheumatic heart disease and coronary artery disease.1 Several studies have documented the strong relation between chronic AF and emboli.2,3 In addition, an increased risk of embolism exists in the setting of cardioversion of AF to sinus rhythm.4,5 In the best study to date, Bjerkelund and Orning6 reported on 572 attempted cardioversions in 437 patients and observed a 0.8% incidence of embolization in long-term anticoagulated patients compared with 5.3% in a nonanticoagulated group. Shortcomings of this study included lack of randomization, no evaluation of shortterm therapy and inclusion of arrhythmias such as atrial flutter and atrial tachycardia. Based on such work, current recommendations include anticoagulation for 2 to 4 weeks before cardioversion to allow adherence and endothelialization of existing thrombus and 1 to 4 weeks after cardioversion to provide coverage for late resumption of atrial activity.7,8 The present report evaluates these recommendations in light of our experience over the past 10 years.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28015/1/0000451.pd

Quantitative regional curvature analysis: Validation in animals of a method for assessing regional ventricular remodelling in ischemic heart disease

Recent studies show the impact of left ventricular shape and remodelling on patient prognosis. This mandates the development of quantitative methods for measuring shape. Quantitative regional curvature analysis (QRCA) was developed to quantitate shape on a regional basis so that measurements would not be constrained to assessment of only global shape and would, therefore be applicable to ischemic heart disease. To validate QRCA, eleven dogs were instrumented with coronary occluders and radiopaque markers on the epicardium and endocardium to provide fiducial points for calculation of shape, motion and thickening. These parameters were measured in the anterior and inferior walls, at rest, during left anterior descending occlusion and finally during circumflex occlusion. QRCA showed increased curvature (increased globularity) in each wall when thickening and motion deteriorated during occlusion. The most marked shape changes occurred in the inferior wall whereas the most marked deterioration of function was detected by wall thickening measurements of the anterior wall. Thus, QRCA detects regional ventricular shape disorders coincident with regional dysfunction induced by ischemia. These changes show regional heterogeneity and demonstrate the potential importance of this measurement as opposed to simple, global measures of shape. QRCA is, therefore, suitable for monitoring acute changes of shape that occur during acute ischemia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42545/1/10554_2005_Article_BF01798047.pd

The effects of acute ischemia on the isovolumic index

The isovolumic index is the ratio of the duration of isovolumic contraction (IVC) and relaxation (IVR) divided by ejection time (ET), and has been proposed as a more sensitive descriptor of ventricular performance than the systolic time index, which ignores the period of isovolumic relaxation. To determine the effects of acute ischemia on these indices, IVC, IVR, and ET were measured in seven open-chest dogs instrumented with high-fidelity micromanometers and ultrasonic crystals and subjected to a 10-second period of coronary occlusion. Fractional shortening was significantly impaired (18.4 +/- 6.9% vs 1.9 +/- 7.3%, p p p p p < 0.05 cs control), though ET and the systolic time index were unchanged. Through incorporation of IVR, the isovolumic index was more sensitive to acute brief ischemia than the systolic time index.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27601/1/0000645.pd

The hemodynamic determinants of the isovolumic index

The isovolumic index is a recently described echocardiographic parameter of left ventricular function that is calculated as the ratio between the sum of the time of isovolumic contraction and relaxation divided by the ejection time. Although the individual components of this index may be altered by heart rate and loading conditions, an analysis of the net effect of such alterations on the isovolumic index has not been undertaken. Thus, dogs were instrumented with high-fidelity micromanometers in the left ventricle, ascending aorta, and left atrium to allow determination of the individual comoonents of the isovolumic index and calculation of the index itself. Four sets of experiments were undertaken in random order. Left atrial pacing was used to increase heart rate by approximately 10 bpm in five steps. Preload was elevated in five stages by saline infusions which caused successive increases of 1 to 2 mm Hg in the left ventricular end-diastolic pressure. Systolic blood pressure was lowered or raised by approximately 10 mm Hg per stage by three progressive, steady-state infusions of nitroprusside and phenylephrine, respectively. These experiments demonstrated little change in the isovolumic index over a broad range of heart rate. Increased left ventricular end-diastolic pressure and decreased systemic pressure caused shortening of the index. Multiple regression analysis of all experiments yielded the following: isovolumic INDEX = 0.41 - 0.015 (left ventricular end-diastolic pressure) + 0.004 (systolic blood pressure); r = 0.57, standard ERROR = 0.13, p < 0.0001. Therefore, this investigation establishes the hemodynamic determinants of the isovolumic index and provides the basis for interpretation of directional changes in response to cardiac diseases and cardioactive drugs that can alter loading conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26036/1/0000109.pd

Effect of coronary stenosis severity on variability of quantitative arteriography, and implications for interventional trials

Quantitative coronary arteriography is now routinely used in studies assessing arterial remodelling in response to interventions such as lipid lowering and percutaneous transluminal coronary angioplasty. Although this methodology provides both relative and absolute measurements that can be evaluated statistically as continuous variables, it is, however, often desirable or necessary to establish categorical responses to the interventions based on the variability inherent in the quantitative methods (i.e., it is often necessary to state whether individual patients, as opposed to entire groups, have "restenosed," "progressed," "regressed," and so forth, and these categorical designations are based on critical limits of variability). 1,2 These limits are generally based on an analysis of a rather diverse range of lesion severity, and the question arises as to whether the variability of measuring changes in lesion or segment morphology is affected by the initial severity of the lesion being studied. It is conceivable that variability may be greater at 1 end than at the other end of the spectrum of lesion severity. If this is true, then the use of 1 critical value to designate whether a subject has responded in a certain way would be inappropriate, and this designation would be better achieved by using criteria that more directly reflect the measurement variability of lesions of a specified, initial severity. This report examines whether the variability of measuring morphologic parameters of stenoses is affected by the baseline severity of the lesion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30152/1/0000529.pd

A comparison of traditional wall motion assessment and quantitative shape analysis: A new method for characterizing left ventricular function in humans

To forego the need to arbitrarily choose coordinate, reference, and indexing systems and to make other assumptions mandated by traditional methods of measuring walf motion, a technique of regional function analysis based on shape characteristics and pattern recognition was developed. The method is based on curvature analysis, a fundamental shape parameter, and is adaptive to the complex geometry of cineangiographic ventricular images. Quantitative shape parameters were compared to a standard method of regional function analysis (center-line method) in 130 patients. Quantitative shape and wall motion indexes showed a positive correlation over a broad range of normal and abnormal function (r = 0.748, p < 0.001). Overall sensitivity and specificity for categorization of regional function were not statistically different for either technique. Within regions, however, shape criteria were more specific in categorizing inferior zones than anterior zones and were more often abnormal in the presence of mild regional abnormalities that were not located in the apical region. In conclusion, shape analysis and pattern recognition techniques can be used to forego dependence on the numerous assumptions and approximations required by traditional wall motion techniques, while providing performance characteristics that are similar to, and in some instances better than, traditional approaches. Incorporation of shape information in assessments of regional function provides a more comprehensive evaluation that includes the important visual cues used by experienced observers or "experts."Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26530/1/0000069.pd

Evidence of abnormal vasodilator reserve in coronary spasm

Although reduction of coronary flow reserve (CFR) is a common consequence of significant coronary stenoses, recent observations suggest that it may also be abnormal in other clinical settings such as myocardial hypertrophy or syndrome X in the absence of stenoses.1,2 This report shows that the CFR may also be abnormal in patients with normal coronary arteries and vasospasm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26259/1/0000340.pd