Imaging cerebral amyloid angiopathy with susceptibility-weighted imaging.

Gradient-echo (GE) imaging is recognized as a means to detect hemorrhagic changes in cerebral amyloid angiopathy (CAA). However, almost 25% of patients with CAA do not show microhemorrhages on T2* GE imaging. We applied a new imaging method, susceptibility weighted imaging (SWI), to evaluate the presence of microhemorrhages. In a suspected case of CAA, where cognitive effects are also present, we show that SWI is much more sensitive in detecting microhemorrhages than conventional methods.

A four-shock Bayesian up-down estimator of the 80% effective defibrillation dose.

INTRODUCTION: New defibrillation techniques are often compared to standard approaches using the defibrillation threshold. However, inference from thresholding data necessitates extrapolation from reactions to relatively ineffective shocks, an error prone procedure requiring large sample sizes for hypothesis testing and large safety margins for defibrillator implantation. In contrast, this article presents a clinically validated statistical model of a minimum error, four-shock defibrillation testing protocol for estimating the 80% effective defibrillation strength for a given patient (ED80). METHODS AND RESULTS: A Bayesian statistical model was constructed assuming that the defibrillation dose-response curve is sigmoidal, and the ED80 is between 150 and 750 V. The model was used to design a minimum predicted error testing protocol and estimates. To prospectively validate the testing protocol and estimates, 170 patients received voltage-programmed biphasic testing. Four fibrillation episodes were induced and terminated in each patient according to the Bayesian up-down protocol. In addition, a validation attempt was made at the estimated ED80 rounded up to the nearest 50 V. In order to estimate the safety margin, in 136 patients, a defibrillation attempt was made at the rounded ED80 + 100 V. Of the 170 attempts at the rounded ED80, 143 (84%) attempts terminated fibrillation. Of the 136 attempts at the rounded ED80 + 100 V, 133 (98%) were effective. CONCLUSIONS: The four-shock Bayesian up-down protocol is the first clinical protocol to accurately predict an ED80 voltage. A 100 V increment above the ED80 provides an adequate safety margin. This simple and accurate method for estimating a highly effective defibrillation dose may be a valuable tool for population-based clinical hypothesis testing, as well as defibrillator implantation.

Mitral valve repair combined with aortic valve replacement.

BACKGROUND AND AIMS OF THE STUDY: Combined aortic and mitral valve replacement continues to result in significant morbidity and mortality. Although mitral repair has improved the results of mitral valve surgery, its influence on combined aortic valve replacement has not been assessed. METHODS: We reviewed 38 consecutive patients who underwent aortic valve replacement (AVR) and mitral repair (MR) between 1985 and 1995. The average age was 57 years; 20 were men and 18 women. Nineteen patients were considered high risk: six had previous cardiac surgery, three were on chronic dialysis, two required emergency surgery for low output syndrome, one had a chronic tracheotomy for chronic lung disease, and seven had left ventricular ejection fraction < 30%. MR consisted of ring application alone in 28 patients, chordal shortening in nine, posterior leaflet transfer in six and posterior leaflet resection in four. AVR was accomplished with 21 bioprostheses, 14 mechanical and three allograft valves. The mean (+/-SD) cross-clamp time was 133 +/- 41 min. Additional procedures included coronary bypass in six patients and tricuspid procedures in three. RESULTS: There were no operative deaths. Six patients died between 4 and 73 months postoperatively. Patient survival was 75% five and 67% 10 years after surgery. The causes of death were heart failure (two cases), and respiratory failure, drug overdose, electrolyte imbalance and unknown (one each). Logistic risk analysis was significant for females and rheumatic valve disease, bacterial endocarditis, and degenerated valve patients. During follow up there were no valve failures or endocarditis, but three embolic episodes occurred without permanent sequel. CONCLUSIONS: With increased surgical expertise, improved myocardial protection of MR combined with AVR offers excellent short- and long-term results, optimal chordal preservation, no valve failure and no endocarditis; it is the ideal choice where anti-coagulation is contraindicated. The prolonged cross-clamp time was well tolerated.

Measurement of myocardial blood flow by ultrafast computed tomography.

Myocardial blood flow was analyzed by radioisotope-labeled microspheres and ultrafast computed tomography (CT) in 16 closed-chest, anesthetized dogs. The first set of 10 dogs had CT and microsphere measurements before and after chromonar-induced increases in myocardial blood flow. A second set of six dogs had flows measured at control and during temporary reductions in regional flow produced by balloon cuff occlusion of the left anterior descending coronary artery. All dogs had four-slice, 20-instance CT scans after injection of a medium bolus (0.35 ml/kg) of contrast medium into a femoral vein simultaneous with injection of microspheres into the left atrium. CT myocardial flow was calculated as the change in myocardial CT numbers divided by the area from a blood pool time-density curve. A wide range of myocardial blood flows was produced as determined by microspheres (0 to 6.7 ml/min/g). Global flow of the first set of dogs was shown to have excellent correlation (r = .95, n = 17) for a limited range (.4 less than X less than 1.4 ml/min/g) of flows. Regional flows of these measurements demonstrated less correlation (r = .63, n = 110) but extended the range of flow to 1.7 ml/min/g. At higher flows (greater than 2.5 ml/min/g) the correlation for global and regional flows was not significantly different than zero. Regional ischemic flow correlation extended the linear range of flow to 0 ml/min/g (r = .62, n = 17). These results show that CT can measure myocardial blood flow over a limited but clinically relevant range of flows defined as slightly above normal to ischemic. These results indicate that another preparation of CT flow measurement must be sought for quantification of myocardial perfusion values significantly above normal.

The spectrum of myocardial contusion: a review.

Blunt trauma to the chest and abdomen frequently results in cardiac injury. A wide spectrum of pathology can follow, including myocardial concussion and contusion, valvular disruption, and pericardial effusion and tamponade. Likewise, sequelae may be inconsequential or lead to sudden death, and may occur immediately at the time of trauma or be delayed by days to years. Despite the increasingly common occurrence of myocardial contusion there remains much confusion as to how the diagnosis is made. The various diagnostic studies utilized are frequently misinterpreted. The pathophysiology, clinical presentation, and a critical evaluation of the diagnostic tests used in the confirmation of this entity are reviewed, and an approach to the evaluation and management of these patients is presented.

Academic freedom and the classified information system.

Executive Order 12356, signed by President Reagan on 2 April 1982, prescribes a system for classifying information on the basis of national security concerns. The order gives unprecedented authority to government officials to intrude at will in controlling academic research that depends on federal support. As such, it poses a serious threat to academic freedom and hence to scientific advances and the national security.

[Epidemiologic study of 500 adult epileptics from a hospital population]. / Estudio epidemiológico de 500 epilépticos adultos procedentes de una población hospitalaria.

An epidemiology analysis is carried out in a hospital population of 500 epileptic patients older than 14 years of age, pertaining to the outpatient department of the Instituto de Neurología, Hospital de Clínicas, Monevideo". This information gathered, corresponds to the period, 1966-1975. Specially formulated records of precoded-type data were used for this research and the data was processed by automation. This work deals fundamentally with a descriptive study in which the character of the population and of its epilepsy is studied by means of 20 items. Analyzed from within the social aspects, the school attendance and the occupation of the patients, amounts, similar to those of the general population of the country, were found. An elevated incidence of family epilepsy antecedents (17%) in the group and also of perinatal pathology (19%), is emphasized. An analytic study of the clinical type of crisis and of the factors unleashed by the attacks is made. Dividing the population into two groups, according to the beginning of epilepsy, before or after the 25 years, the different etiology for both groups is specially pointed out, the juvenile epilepsy predominating in the unknown etiology, genetics and that which is produced by perinatal pathology, while in the tary epilepsy, the vascular and tumoral etiology, above all, is most frequent.

[Epidemiology of 500 adult epileptics from a hospital population]. / Estudio epidemiológico de 500 epilépticos adultos procedentes de una población hospitalaria.

On the basis of 500 epileptic patients treated in the Out-Patient Department of the "Instituto de Neurología", Hospital de Clínicas, Montevideo, Uruguay, an epidemiological study is undertaken. Data obtained correspond to the period extending between 1965 and 1975. A precodified data registering system was used and the analysis was done by mechanical processes. It is mainly a descriptive analysis of the group of patients and their seizures, including 20 items. As far as social aspects are concerned, education levels and occupation are analyzed, encountering similar levels as those of the general population in this country. As to etiological factors, a high incidence of familiar history of epilepsy (17%) and of perinatal pathology (19%) is found. An analytical study of the seizures and their provoking factors is performed. Etiological factors are analyzed dividing the patients in two groups according to the age of beginning of seizures (before or after 25 years) and in the younger groups perinatal factors and epilepsy of unknown origin predominate, while in the older group vascular and tumoral causes are more frequent.