Search

The ever-growing amount of data requires highly scalable storage solutions. The most flexible approach is to use storage pools that can be expanded and scaled down by adding or removing storage devices. To make this approach usable, it is necessary to provide a solution to locate data items in such a dynamic environment. This article presents and evaluates the Random Slicing strategy, which incorporates lessons learned from table-based, rule-based, and pseudo-randomized hashing strategies and is able to provide a simple and efficient strategy that scales up to handle exascale data. Random Slicing keeps a small table with information about previous storage system insert and remove operations, drastically reducing the required amount of randomness while delivering a perfect load distribution. © 2014 ACM.

A method is proposed for comparing the orifice size and the morphology of stenotic mitral valves, removed intact at the time of replacement, with the preoperative two dimensional echocardiographic cross-sections. The excised mitral valve apparatus is suspended on a specially constructed mounting. To avoid shrinkage the orifice is stabilised with an airfilled balloon. A radiography is taken directing the x-ray beam perpendicular to the valve orifice. In 40 of 51 patients this method provided the means of relating the echocardiographic cross-sections to the morphology of the valve. Planimetry of the valve area compared favourably with the postoperatively determined orifice size. Agreement was found in 34 of 40 patients in orifice shape between preoperative echocardiograms and x-rays of th excised valve. The relation between intraoperative estimation of size of the valve, using dilators with known diameters, and the postoperative results was less favourable. Areas of calcification were identified on echocardiography as dense conglomerate echoes. In 30 patients (75%) the localisation of calcium deposits and in 67% the degree of calcification was in agreement with the x-rays of the valve taken after operation. In addition to determination of the area, two dimensional echocardiography allows detailed studies of the stenotic valves, and is of particular importance for planning operative treatment. [ABSTRACT FROM PUBLISHER]

A group of 111 patients with mitral valve disease was studied by M-mode and two-dimensional echocardiography. Five left atrial thrombi were demonstrated, two of which had probably been the source of previous embolic events. Two-dimensional echocardiography was superior to M-mode in providing spatial orientation. Using multiple cross-sections the exact localisation and the size of the thrombus formation could be estimated. Thrombus localisations at the upper, lateral, and septal atrial walls, normally inaccessible to the single-beam technique, were successfully imaged. Even two-dimensional echocardiography, however, constitutes an imperfect method. By comparison with the findings at surgery only one-third of confirmed thrombi could be detected non-invasively. According to their localisation seven clots in the appendage were missed by the ultrasound method. One further thrombus fixed to the upper left atrial wall near the entrance of the upper pulmonary veins was also undetected by echocardiography. Despite these limitations, the information provided by echocardiography can be most helpful in patient management. M-mode, in combination with two-dimensional echocardiography, is therefore recommended in all patients with mitral stenosis before diagnostic or therapeutic procedures are undertaken. [ABSTRACT FROM PUBLISHER]

Peak and mean left ventricular ejection power were measured during atrial pacing in 6 normal subjects (group I), 6 patients with coronary artery disease without myocardial infarction (group IIa), and 10 patients with coronary artery disease after myocardial infarction (group IIb). Pacing rates were 80 and 120/min. Power was determined by computer analysis of pressure, volume, and time. Data were normalised by end-diastolic volume and left ventricular muscle mass. Peak left ventricular ejection power normalised by end-diastolic volume values at a pacing rate of 120 min were significantly lower in group IIa and IIb than in normal subjects. Mean muscle mass in normal subjects was 179 g and in group IIa 216 g (P smaller than 0.05). Peak power normalised by muscle mass in normal subjects tended to increase at 120/min whereas in group IIa it declined by 26 per cent (P less than 0.001). These data indicate that the energy output of the left ventricle at rest may be the same in patients with significant coronary artery disease as in normal subjects. Increasing the heart rate from 80 to 120/min in a normal myocardium augments power but in coronary artery disease it remains static or falls. [ABSTRACT FROM PUBLISHER]

Two cases of the gap phenomenon are presented. The first was an example of a gap between the atrium and the AV node. In the second the gap was at the nodo-Hisian junction. At a critical H1H2 interval splitting of the premature His potential occurred. A decrease of the H1H2 interval led to the disappearance of the distal H2 potential and to atrioventricular block. But at even shorter coupling intervals the H1H2 interval lengthened suddenly with resumption of the AV conduction. These observations provide further evidence that the gap phenomenon has a wider spectrum than was previously thought. [ABSTRACT FROM PUBLISHER]

In a consecutive series of 56 patients with acute myocardial infarction, ST segment depression and elevation in the electrocardiographic limb leads I, II, and III were summated for each patient before and immediately after intracoronary streptokinase infusion and the results compared with the angiographic findings. Forty three patients had angiographically confirmed reperfusion of an initially occluded vessel and showed a significant decrease in summated ST shift. The ST segment changes in the limb leads virtually returned to normal in all 43 patients, and in most, inverted T waves developed. Thrombolysis was unsuccessful in 10 patients, and the infarct related coronary artery was already patent in three. When these two groups are combined, all 13 patients without reperfusion showed no significant change in summated ST segment shift. During percutaneous transluminal angioplasty inflation of the balloon in the vessel that was previously occluded simulated reocclusion and was followed by new ST elevation if the artery supplied viable myocardium. In a further consecutive study of 54 patients with anterior myocardial infarction, the precordial R waves and Q waves were studied over the four to six months following infarction using a standardised 48 electrode mapping system. All patients underwent a repeat angiogram after four to six months. In 36 patients the infarct related vessel was patent. They showed a significant mean increase in summated precordial R wave amplitude and a reduction in the mean number of precordial leads without R waves. In 18 patients with unsuccessful thrombolysis or reocclusion there was a further reduction in mean summated R wave amplitude and an increased number of precordial leads not showing R waves. Precordial R wave mapping seems to be a valuable non-invasive method of assessing the salvage of myocardium after reperfusion and the damage caused by reocclusion. Loss of R waves in the acute phase of myocardial infarction does not necessarily mean an irreversibly damaged myocardium. [ABSTRACT FROM PUBLISHER]

To study the long-term results of tricuspid valvuloplasty, pre- and postoperatively (39 +/- 11 months), echocardiographic and catheterization data were collected in 37 patients (mean age, 58 +/- 8 years). Because of severe mitral stenosis, all patients received a porcine heterograft in the mitral position and underwent reconstructive tricuspid surgery with Carpentier rings (#32, n = 12; #34, n = 15; #36, n = 10). Sizing was performed by measuring the anterior leaflet area using an obturator. In nine patients, tricuspid leaflets were slightly shrunken at the insertion site of the chordae tendineae. Postoperative echocardiography and right heart catheterization were performed with simultaneous pressure recordings in the right ventricle and right atrium. A significant clinical improvement was noted in 24 patients, and this correlated with significant hemodynamic improvement. In eight patients, no clinical improvement was observed. Patients were divided into subgroups according to echocardiographic and hemodynamic criteria. Group A (n = 17) was composed of patients with significant improvement of hemodynamics, without detectable tricuspid valve dysfunction. Group B (n = 11) was composed of patients with slight-to-moderate tricuspid incompetence, detected by contrast echocardiography. In nine of these patients, the size of the RA and the diameter of the IVC were significantly smaller than preoperatively. In patients of Group C, echocardiography and catheterization data showed a slight-to-moderate tricuspid stenosis with a mean diastolic pressure gradient of 3.9 +/- 1.4 mm Hg (max 6.2 mm Hg, min 2.4 mm Hg). Although the area of the anterior tricuspid leaflet was slightly underestimated, we determined that long-term results of tricuspid valve annuloplasty with a Carpentier ring were encouraging.

Transluminal coronary angioplasty was performed in 21 of 64 patients with acute myocardial infarction treated initially with intracoronary streptolysis. Successful reduction of the coronary stenosis was achieved in 17 cases. Six months later 11 of 12 of these patients studied by coronary arteriography still had patent areas of previous coronary stenosis.

In 125 patients successfully treated by intracoronary thrombolysis, data were analyzed to determine the amount of regional wall motion impairment. In 85 patients with complete occlusion of the affected vessel and successful recanalization, ventriculographic study could be performed immediately after recanalization of the vessel and repeated 3 days thereafter. Unexpectedly, no correlation could be seen between the amount of wall motion impairment and the time interval of coronary vessel occlusion. For assessment of other influencing factors two subgroups were analyzed, one with large infarction despite short occlusion time and the other with small infarction despite long occlusion time. The significant differences between these two groups was in regard to the occluded coronary vessels: In the first group, most patients had anterior infarctions caused by left anterior descending (LAD) occlusion, whereas in the second group, there were no LAD occlusions at all. According to the data that we compiled, the location of the occluded coronary vessel was the most important factor in determining infarct size. Taking this into account, recovery of the impaired wall motion up to the third day after infarction was separately analyzed in LAD occlusion or inferior infarction and was found to be more pronounced in the first. Immediate recovery after recanalization however, which could be analyzed in 40 patients who had angiographic studies before recanalization as well as afterwards, was more pronounced in inferior infarction.

Thrombolytic therapy for acute myocardial infarction reduces early mortality, but full recovery of left ventricular function after reperfusion is delayed. Therefore, the relations among reperfusion, survival and the time course of left ventricular functional recovery were examined in 226 patients treated with intracoronary streptokinase; 77% (134 patients) had sustained reperfusion and 31 patients had no reperfusion or had reocclusion by day 3. Wall motion was measured from contrast ventriculograms performed in the acute period and 3 days later in the central and peripheral infarct regions and the noninfarct region by the centerline method in 165 patients. Patients with reperfusion had better survival (p less than 0.05, mean follow-up 4.5 years) and a higher ejection fraction at 3 days (52 +/- 12 versus 46 +/- 10%, p less than 0.02) attributable to a significantly different change in peripheral infarct region function between the acute and 3 day studies (0.1 +/- 1.0 versus -0.3 +/- 0.9 SD, p less than 0.05). These early functional changes were significant in patients with anterior myocardial infarction and showed similar trends in those with inferior myocardial infarction. On Cox regression analysis, function measured at 3 days was more predictive of survival than was function measured acutely (chi square for acute ejection fraction = 11.48 versus 24.59 at 3 days). Although, as previously reported, greater than 45% of total recovery of left ventricular function occurs later, the ejection fraction achieved by day 3 is already predictive of survival. Thus, the mechanism by which successful thrombolytic therapy enhances survival is improvement of regional and global left ventricular function early after acute myocardial infarction.

Selective intracoronary thrombolysis with streptokinase was successful in 72 of 84 (86%) patients admitted to the hospital with definitive signs of acute transmural myocardial infarction due to complete occlusion of either the left anterior descending coronary artery, the right coronary artery, or the circumflex artery. The average time between onset of acute symptoms and medically induced reperfusion was 241 +/- 90 minutes (SD). Reperfusion resulted in prompt relief of pain, regression of cardiogenic shock, and normalization of electrocardiograms. Follow-up treatment was either medical or surgical. The 32 medically treated patients had a high reocclusion rate, with 6 fatal (19%) and 9 nonfatal (28%) reinfarctions. In order to the reduce the risk of reinfarction, additional simultaneous transluminal balloon angioplasty was done in a recent series of patients with stenoses accessible to this technique. The best early and long-term results were achieved in 17 patients who underwent coronary artery bypass grafting within three days after successful thrombolysis. There was no operative mortality, and subsequent bleeding has not been a problem. It is concluded that early operation is the treatment of choice in all patients suitable for such intervention who have undergone successful intracoronary thrombolysis within 4 hours after onset of acute myocardial infarction. Late coronary bypass operation should be reserved for symptomatic patients who have definitive signs of infarction in spite of successful thrombolysis.

A comparison of clinical data has shown that percutaneous transluminal coronary angioplasty can be performed with equally good results in unstable and stable angina pectoris. Transluminal coronary angioplasty and coronary bypass surgery do not alter the natural progression of coronary atherosclerosis, but coronary angioplasty provides a real chance at least to postpone bypass graft surgery if not to provide lasting relief of angina.

Sublingual nifedipine 20 mg as an emergency treatment for severe hypertension or hypertensive crisis in 30 patients gave an effective and gradual reduction in blood pressure. Side effects were rare and not severe. The heart rate remained fairly stable or sometimes even decreased. Thus, sublingual nifedipine may now be considered a reasonable first choice in the treatment of severe hypertension or hypertensive crisis.

Successful thrombolysis for acute myocardial infarction reduces early mortality. For definite correction of the underlying arteriosclerotic lesion, invasive treatment is mandatory. Early bypass grafting has been performed in 70 patients with an ischemic interval of less than 4 hours before reperfusion by thrombolysis. Surgery was undertaken an average of 4.5 days after the streptokinase administration. The hospital mortality rate was 1.4%. At 8 years the actuarial survival rate was 88% and the complication-free survival rate, 84%. At the latest follow-up study, 90% of the patients were in functional class I or II. Because of advanced age, 37% of the survivors have retired and 29% are working. Thirty-four percent did not return to work after the operation. In 24 patients a transmural needle biopsy specimen was taken at operation to study the extent of ischemic damage. Surprisingly, the extent of necrosis did not correlate with the ischemic interval (r = 0.17), whereas enzyme activity and extent of necrosis did correlate (r = 0.76). Late angiography was done in 44 patients (56%). The correlation between ischemic interval and regional wall motion score was weak when the whole group was considered (r = 0.35), but 70% of the patients with an ischemic interval of less than 3 hours had normal or near normal regional wall motion. In patients with prolonged ischemia, distribution between normal function and severe damage was uniform. In patients with ultrastructural and wall motion studies, early necrosis and late left ventricular function correlated fairly well (r = 0.69). We conclude that additional early bypass grafting after successful thrombolysis yields excellent long-term clinical results, especially in patients with an ischemic interval of less than 3 hours.