Stroke Count Research Articles

Development, Validation, and Application of a Microsimulation Model to Predict Stroke and Mortality in Medically Managed Asymptomatic Patients with Significant Carotid Artery Stenosis

Objective To develop a model to predict stroke-free survival and mortality over a multiyear time frame for a trial-excluded population of medically managed asymptomatic patients with significant carotid artery stenosis. Methods We calibrated, validated, and applied a Monte Carlo microsimulation model. For calibration we adjusted general-population mortality and stroke risks to capture these risks specific to asymptomatic carotid stenosis patients. For validation, we compared model-predicted and actual stroke-free survival curves and stroke counts from a population of comparable patients. For application, the validated model predicted stroke-free survival for a hypothetical medically managed arm of a recent single-arm carotid revascularization trial. Results For each month in the 60-month time frame, the model-predicted and actual calibration trial stroke-free survival curves were not statistically different ( P > 0.62). In validation, the calibrated model's stroke-free survival curvematched the actual curve from an independent population; beyond 24 months, the model-predicted and actual curves were not statistically different ( P > 0.32). We also compared model-predicted and actual number of strokes from the independent trial. The model predicted 187.25 strokes (95% confidence interval 161.49–213.01), while the actual number was 171.6, within 1.22 standard deviations of the simulated mean. Conclusions Given the absence of medically managed populations in recent carotid stenosis trials, our model can estimate stroke-free survival and mortality data for these patients. The model may also estimate the effectiveness of novel medical and procedural therapies for stroke prevention. These effectiveness estimates can inform the development of policies, guidelines, or cost-effectiveness analyses when only single-arm trial data exist.

Diurnal Variation in Swim Performance Remains, Irrespective of Training Once or Twice Daily

Fast swim times in morning rounds are essential to ensure qualification in evening finals. A significant time-of-day effect in swimming performance has consistently been observed, although physical activity early in the day has been postulated to reduce this effect. The aim of this study was to compare intradaily variation in race-pace performance of swimmers routinely undertaking morning and evening training (MEG) with those routinely undertaking evening training only (EOG). Each group consisted of 8 swimmers (mean +/- SD: age = 15.2 +/- 1.0 and 15.4 +/- 1.4 y, 200-m freestyle time 132.8 +/- 8.4 and 136.3 +/- 9.1 s) who completed morning and evening trials in a randomized order with 48 h in between on 2 separate occasions. Oral temperature, heart rate, and blood lactate were assessed at rest, after a warm-up, after a 150-m race-pace swim, and after a 100-m time trial. Stroke rate, stroke count, and time were recorded for each length of the 150-m and 100-m swims. Both training groups recorded significantly slower morning 100-m performances (MEG = +1.7 s, EOG = +1.4 s; P < .05) along with persistently lower morning temperatures that on average were -0.47 degrees C and -0.60 degrees C, respectively (P < .05). No differences were found in blood-lactate, heart-rate, and stroke-count responses (P > .05). All results were found to be reproducible (P > .05). The long-term use of morning training does not appear to significantly reduce intradaily variation in race-pace swimming or body temperature.

Influences of Swimsuit Design on Swimming Performance in Competitive Female Swimmers

Recently, designs for competitive swimsuits have become diversified. The influences of new swimsuit design on drag, buoyancy and physiological responses were measured in the previous studies. However, few studies have evaluated the association between swimsuit and performance during maximal swimming. PURPOSE: To examine the swimming speed, blood lactate, heart rate, perceptual response and stroke technique during freestyle swimming wearing a traditional body suit and a newly designed swimsuit. METHODS: Six competitive female swimmers (age, 19.0±0.6 yr; height, 161.8±5.3 cm; body weight, 52.7±3.5 kg) swam a 200-m maximal freestyle trial in a 25-m indoor pool wearing a traditional body suit (BS) and a suit designed to cover the body from shoulder to ankle (LJ). Blood lactate concentration (BLa), heart rate (HR) and rating of perceived exertion (RPE) were measured after the trial. Stroke counts were determined to calculate the arm stroke index (ASI) during swimming trials. Each subject was informed of the aims, possible risks, and benefits of this investigation both verbally and in writing prior to their signing an informed consent document. RESULTS: Maximal swimming velocity between the BS (1.483 ± 0.006 m/s) and LJ (1.496 ± 0.011 m/s) trial demonstrated no significant difference, but the four swimmers swam faster in the LJ trial (mean time 1.1 sec; range from 0.6 to 3.3 sec) than the BS trial. BLa (BS: 11.32 ± 1.26 mmol/l vs. LJ: 12.95 ± 1.43 mmol/l), HR (BS: 190.2 ± 4.6 bpm vs. LJ: 190.4 ± 4.7 bpm), and RPE (BS: 19.0 ±0.3 vs. LJ: 18.8 ± 0.5) between the two suit conditions at the completion of the maximal trial were not significantly different. ASI (BS: 97.37 ± 3.97 vs. LJ: 97.90 ± 4.85) that was calculated by dividing the number of total strokes by the velocity was also not significantly different between the suits. CONCLUSIONS: These findings indicate that the new type of swimsuit during maximal freestyle swimming does not provide a physiological and technical advantage.

Short-term effects of ozone air pollution on ischaemic stroke occurrence: a case-crossover analysis from a 10-year population-based study in Dijon, France

Objective: To evaluate the association between air pollutants and the occurrence of acute stroke from 10-year population-based study. Methods: The daily stroke count was obtained from Dijon Stroke Register between...

Performance Assessment of the World Wide Lightning Location Network (WWLLN), Using the Los Alamos Sferic Array (LASA) as Ground Truth

Abstract The World Wide Lighting Location Network (WWLLN) locates lightning globally, using sparsely distributed very low frequency (VLF) detection stations. Due to WWLLN’s detection at VLF (in this case ∼10 kHz), the lightning signals from strong strokes can propagate up to ∼104 km to WWLLN sensors and still be suitable for triggering a station. A systematic evaluation of the performance of WWLLN is undertaken, using a higher-frequency (0–500 kHz) detection array [the Los Alamos Sferic Array (LASA)] as a ground truth during an entire thunderstorm season in a geographically confined case study in Florida. It is found that (a) WWLLN stroke-detection efficiency rises sharply to several percent as the estimated lightning current amplitude surpasses ∼30 kA; (b) WWLLN spatial accuracy is around 15 km, good enough to resolve convective-storm cells within a larger storm complex; (c) WWLLN is able to detect intracloud and cloud-to-ground discharges with comparable efficiency, as long as the current is comparable; (d) WWLLN detects lightning-producing storms with high efficiency in every 3-h epoch; thus, WWLLN can be useful for locating deep convection for weather forecasting on 3-h update cycles; and (e) WWLLN detects a stroke count in each storm that is weakly proportional to the stroke count detected by LASA. Thus, to the extent that lightning rate can serve as a statistical proxy for rainfall, WWLLN may eventually provide rainfall-proxy data to be assimilated in 3-h forecast update cycles.

A kinetic analysis of manual wheelchair propulsion during start-up on select indoor and outdoor surfaces

The objective of this study was to conduct a kinetic analysis of manual wheelchair propulsion during start-up on select indoor and outdoor surfaces. Eleven manual wheelchairs were fitted with a SMART(Wheel) and their users were asked to push on a course consisting of high- and low-pile carpet, indoor tile, interlocking concrete pavers, smooth level concrete, grass, hardwood flooring, and a sidewalk with a 5-degree grade. Peak resultant force, wheel torque, mechanical effective force, and maximum resultant force rate of rise were analyzed during start-up for each surface and normalized relative to their steady-state values on the smooth level concrete. Additional variables included peak velocity, distance traveled, and number of strokes in the first 5 s of the trial. We compared biomechanical data between surfaces using repeated-measures mixed models and paired comparisons with a Bonferroni adjustment. Applied resultant force (p = 0.0154), wheel torque (p < 0.0001), and mechanical effective force (p = 0.0047) were significantly different between surfaces. The kinetic values for grass, interlocking pavers, and ramp ascent were typically higher compared with tile, wood, smooth level concrete, and high- and low-pile carpet. Users were found to travel shorter distances up the ramp and across grass (p < 0.0025) and had a higher stroke count on the ramp (p = 0.0124). While peak velocity was not statistically different, average velocity was slower for the ramp and grass, which indicates greater wheelchair/user deceleration between strokes. The differences noted between surfaces highlight the importance of evaluating wheelchair propulsion ability over a range of surfaces.

Self-monitoring as an intervention to decrease swimmers' stroke counts.

Self-monitoring of stroke count by swimmers is a common coaching strategy, it is but one that has little data to support it. Although research has demonstrated that self-monitoring can motivate behavior change, little research has focused on whether self-monitoring can enhance skill development. The purpose of the present set of studies was to examine the effects of self-monitoring on the improvement of a specific swimming skill (i.e., stroke count). Eight adult fitness swimmers and three college-level competitive swimmers participated in Study 1. In an A-B-A design, swimmers were observed to reduce stroke counts by about one stroke per lap when instructed to self-monitor and to verbally report strokes. In Study 2. swimmers self-monitored and visually reported strokes on a dry-erase board. A greater improvement was observed in five out of six swimmers. Across studies, stroke counts generally returned to baseline levels when self-monitoring was ended, and improvements during both self-monitoring phases were the greatest in the weakest swimmers. Limitations of the research, mechanisms of change, and implications for coaches are discussed.

Collection of on-line handwritten Japanese character pattern databases and their analyses

We describe the design of on-line handwritten Japanese character pattern databases, software tools for pattern collection and verification, and analyses of collected patterns. Two databases containing over 3 million patterns were compiled: one with 120 people contributing 12,000 patterns each and another with 163 participants contributing 10,000 patterns each. Patterns were collected mostly in their sentential contexts and verified by machine and human inspection. Their analyses reveal greater variations in stroke count for characters having many strokes, with people generally using fewer strokes; they additionally reveal that stroke order variations are generally caused by common habits and added strokes.

The effects of changing pace on metabolism and stroke characteristics during high-speed breaststroke swimming

Performances often vary between the heats and finals of breaststroke swimming competitions possibly because the swimmers try to conserve their energy, or for other tactical reasons. Additionally, coaches might advise either a ‘positive’ or ‘even’ pace race strategy during the final. The effect of such pacing changes on metabolism (blood lactate, heart rate, ventilation), ratings of perceived exertion, stroke kinematics and turning times have not been investigated. Nine male competitive breaststroke swimmers swam three paced (Aquapacer™) 200-m trials, 48 h apart and in random order, at 98%, 100% and at an attempted 102% of their maximal 200-m time-trial speed. Responses in metabolic variables were similar between the 98% and 100% trials, but higher post-exercise blood lactate concentrations and respiratory exchange ratios were observed following the 102% trial. As the pace of trials increased, stroke rate was found to increase proportionately with stroke count. However, during the latter stages of the 100% trial, a disproportionate increase in the stroke count was observed, which led to a significant pacing error. This feature was more obvious in the 102% trial, where participants demonstrated ‘positive pacing’ and reported higher ratings of perceived exertion than for the 98% trial. During the early stages of the trials, turning times were initially shorter the faster the pace of the trial; however, as the trials progressed, this pattern was found to reverse. We conclude that a slight reduction in pace during near maximal breaststroke swimming altered kinematic but not post-exercise metabolic responses, while an increase in pace led to positive pacing and an increase in both kinematic responses and anaerobic metabolism.

Monitoring seasonal and long-term changes in test and competitive performance in elite swimmers

Purpose: To evaluate the utility of an incremental swimming test for monitoring seasonal changes in performance of elite swimmers. Methods: 40 elite swimmers (24 M, 16 F) performed a 7 x 200-m incremental swimming test several times throughout each 6-month season during 1998-2003. Each season concluded with a major competition. Log transformation and repeated measures mixed linear modeling were used to derive estimates of percent change in mean and within swimmercoefficient of variation for swim times between seasons and for the following test measures between phases and seasons: speed, stroke rate, stroke count, and HR at lactate threshold; time for the maximal (last) 200-m step; and maximal lactate. Ability to predict competition time changes was estimated as a within-subject correlation between each measure and performance. A reliability study of 12 swimmers also provided 3-d retest typical error of test measures. Results: Test measures directly related to swimming performance showed cyclical improvement (mean ~2%) from early to taper phases within each season. Within-swimmer variation had similar magnitude. These changes can be monitored confidently in individuals, because the typical error of the test measures was substantially smaller (e.g., lactate-threshold speed, 0.7%; 200-m time, 0.6%). Competition times improved slightly each season (0.7%) against a 1.1% within-swimmer variation between competitions. Only threshold speed, stroke rate and maximal lactate in the taper were moderately correlated (~0.4) with improvements in competition time. Conclusion: The swimming test tracks changes in training performance during a season, but is at best a moderate predictor of competitive performance only during the taper.

Return-Stroke Multiplicity of Negative Cloud-to-Ground Lightning Flashes

The percentage of negative lightning flashes composed of a single stroke is examined. This percentage is estimated from data reported by the U.S. National Lightning Detection Network (NLDN) for Florida and New Mexico and is compared with that determined from electric field and optical observations in these two states. The latter observations allowed a very accurate stroke count and, therefore, were used as the ground truth in the comparison. The percentage of negative single-stroke flashes reported by the NLDN is a factor of 2‐3 higher than from the accurate-stroke-count studies in Florida (44% vs 17%) and is a factor of 3‐4 higher in New Mexico (51% vs 14%). The observed discrepancies suggest that many small subsequent strokes are missed by the NLDN because these strokes fail to exceed the system’s trigger threshold level so that only one stroke per flash is recorded in many multiple-stroke flashes. The percentage of negative single-stroke flashes reported by the Austrian lightning detection network is 40%, similar to the percentages reported by the NLDN for Florida and New Mexico. Percentages of single-stroke flashes determined from accurate-stroke-count studies in Sweden and Sri Lanka, which represent additional meteorologically distinct regimes, are 18% and 21%, respectively, in fair agreement with the Florida and New Mexico accurate-stroke-count studies. From comparison of the NLDNreported and ground-truth data, it is possible to estimate the NLDN stroke and flash detection efficiencies. If the NLDN stroke detection efficiency were the same for both first and subsequent strokes, the percentage of single-stroke flashes and number of strokes per flash reported by the NLDN for Florida (44% and 2.4, respectively) would correspond to a stroke detection efficiency of about 40% and a flash detection efficiency of about 78%. A similar approach to the New Mexico data would yield a stroke detection efficiency of about 20% and a flash detection efficiency of about 62%.

MONITORING LONG-TERM CHANGES IN TEST AND COMPETITIVE PERFORMANCE IN ELITE SWIMMERS

PURPOSETo evaluate the utility of an incremental swimming test for monitoring seasonal changes in performance of elite swimmers. METHODSOlympic representative 100- to 400-m swimmers (10 males, 9 females) performed a 7 × 200-m incremental swimming step test several times throughout each 6-month season during 1998–2002. Each season concluded with a national or international competition. Log transformation and repeated measures mixed linear modeling were used to derive estimates of percent change in the mean and within-swimmer coefficient of variation (CV) for swim times between seasons and for the following test measures between phases and seasons: speed, stroke rate, stroke count and heart rate at lactate threshold; speed for the maximal (last) 200-m step; and maximal lactate. Change in competition time was modeled as a linear function of change in each of the step-test measures between season. We also determined the 3-day retest typical error for the test measures in a reliability study of 12 of the swimmers.RESULTS Test measures directly related to swimming performance showed cyclical improvement (mean ~2%) from early through to taper phases within each season, and within-swimmer variation was of similar magnitude. These changes can be monitored confidently in individuals, because the typical error of the test measures was substantially smaller (e.g. lactate-threshold speed, 0.7%; maximal speed 0.6%). Competition times improved slightly each season (0.2%) against a within-swimmer variation of 1.0% between competitions, but typical (1 × CV) changes in test measures between seasons predicted worthwhile changes in competition time (> 0.4%) only for tests in the taper and only for speed (0.8%) and stroke rate (0.6%) at lactate threshold and for maximum lactate (0.5%).CONCLUSIONThe step test can track changes in a swimmer's performance during a season, but it appears to be useful for predicting competitive performance only during the taper.

Maximum Cardiac Output During Incremental Exercise by First-pass Radionuclide Ventriculography

To validate a noninvasive first-pass radionuclide ventriculographic (FPRV) measurement of maximum cardiac output (Qv) during exercise. Comparison of Qv to that measured by the Fick principle (Qf) at peak exercise. Academic cardiopulmonary exercise laboratory. Seventy-eight consecutive patients without a history of septal defect undergoing clinically indicated maximum incremental cardiopulmonary exercise testing with pulmonary arterial catheterization and FPRV. Ventilation and gas exchange were measured breath-by-breath or by a mixing chamber/mass spectrometer system. Arterial and mixed venous O2 content were measured each minute during exercise. When patients without left-to-right ventricular stroke count ratio evidence for left-sided regurgitation were isolated, peak Qv was linearly related to Qf (r=0.75, p=0.0001). To account for a small systematic overestimation (bias) of Qf by Qv, the linear equation for the Qv/Qf relation was derived for patients studied between 1990 and 1993 and applied to those studied subsequently. The resulting corrected peak Qv was tightly related to peak Qf (r=0.90, p<0.001) with confidence intervals for slope and intercept overlapping identity. FPRV can reasonably estimate maximum cardiac output during incremental exercise in patients for whom the technique has ruled out left-sided cardiac regurgitant lesions.

Off-line handwritten Chinese character recognition as a compound Bayes decision problem

A handwritten Chinese character off-line recognizer based on contextual vector quantization (CVQ) of every pixel of an unknown character image has been constructed. Each template character is represented by a codebook. When an unknown image is matched against a template character, each pixel of the image is quantized according to the associated codebook by considering not just the feature vector observed at each pixel, but those observed at its neighbors and their quantization as well. Structural information such as stroke counts observed at each pixel are captured to form a cellular feature vector. Supporting a vocabulary of 4616 simplified Chinese characters and alphanumeric and punctuation symbols, the writer-independent recognizer has an average recognition rate of 77.2 percent. Three statistical language models for postprocessing have been studied for their effectiveness in upgrading the recognition rate of the system. Among them, the CVQ-based language model is the most effective one upgrading the recognition rate by 10.4 percent on the average.

Effects of Diltiazem on Left Ventricular Systolic and Diastolic Function in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) is characterized by impaired diastolic function, and left ventricular (LV) out-flow tract obstruction in about one-fourth of patients. Verapamil improves diastolic properties, but may have dangerous adverse effects. This study investigates the effects of diltiazem on hemodynamics and LV function in 16 patients with HC who were studied with cardiac catheterization and simultaneous radionuclide angiography. Studies were performed during atrial pacing (15 beats above spontaneous rhythm) at baseline and during intravenous diltiazem administration (0.25 mg·kg −1 over 2 minutes, and 0.014 mg·kg −1·min −1). Diltiazem induced a systemic vasodilation (cardiac index: 3.4 ± 1.0 to 4.0 ± 1.0 L·min −1·m −2, p = 0.003; aortic systolic pressure: 116 ± 16 to 107 ± 19 mm Hg, p = 0.007; systemic resistance index: 676 ± 235 to 532 ± 193 dynes·s·cm −5·m −2, p = 0.006), not associated with changes in the LV outflow tract gradient. The end-systolic pressure/volume ratio decreased (30 ± 42 to 21 ± 29 mm Hg·ml −1·m −2; p = 0.044). Pulmonary artery wedge pressure (11 ± 5 to 15 ± 6 mm Hg, p = 0.006), and peak filling rate increased (4.1 ± 1.3 to 6.0 ± 2.4 stroke counts·s −1, p = 0.004). The time constant of iso-volumetric relaxation τ decreased (74 ± 40 to 59 ± 38 ms, p = 0.045). The constant of LV chamber stiffness did not change. Thus, active diastolic function is improved by the acute administration of diltiazem by both direct action and changes in hemodynamics and loading conditions. LV outflow tract gradient does not increase despite systemic vasodilation. In some patients, however, a marked increase in obstruction and a potentially harmful elevation in pulmonary artery wedge pressure do occur. Passive diastolic function is not affected. (Am J Cardiol 1996;78:451–457)

Correlation between post-ejection shortening and improvement in regional wall motion after revascularization in patients with coronary artery disease

This study investigates the relationship between regional post-ejection shortening and improvement in wall motion after revascularization in patients with severe regional left ventricular contractile dysfunction. Canine studies have documented the phenomenon of post-systolic shortening during acute ischemia, and this predicted recovery of contractile function when ischemia was relieved. This delayed shortening from the ischemic segment would cause regional emptying while the other normal portion of the left ventricle starts to have diastolic relaxation. This was detectable by standard phase analysis of the radionuclide ventriculogram, the abnormal region with delayed emptying being distinguished from the normal portion of left ventricle as an area with a homogeneous phase delay. Twelve patients with successful revascularization and a pre-operative study demonstrating a single homogeneous area of phase delay were identified. The area was demarcated and the regional volume-time curve constructed. The volume-time curve of the abnormal region is analogous to the myocardial segment length versus time relationship in the canine model. We quantitated the amount of delayed (post-systolic) emptying in the demarcated region as the difference between end-systole counts and post-systolic nadir counts, and this was normalised to left ventricular stroke count. After revascularization, regional ejection fraction improved from 44 ± 10% to 62 ± 14% ( P < 0.001), representing a 47 ± 50% improvement over baseline. The percentage improvement in regional ejection fraction correlated with post-systolic emptying ( r = 0.74, P < 0.05) but not with initial regional ejection fraction. In conclusion, post-ejection shortening causes regional post-systolic emptying and this correlates with post-revascularization improvement in regional wall motion.

Gated Versus First-Pass Radioangiography in the Evaluation of Left-to-Right Shunts

Excluding regurgitant ventricles and multiple shunting, left-to-right shunts of the central circulation can be evaluated from the difference between the right ventricular stroke counts (SCRV) and the left ventricular stroke counts (SCLV), which are obtained from gated radioangiography. The pulmonary-to-systemic flow ratio (QP/Qs) is equated to SCRV/SCLV in atrial shunts and to SCLV/SCRV in ventricular and ductal shunts. In this paper, the potentials of the stroke count method have been compared to the gamma fit first-pass technique, incorporating the recent refinements in ductal shunts and deconvolution of the pulmonary curve. In 17 patients with left-to-right shunt, the stroke count method and the gamma fit method correlated moderately with oximetry (r = .71 and .87), respectively. The gamma variate method appeared superior in the detection and estimation of small shunts, whereas when QP/Qs was two or larger, the stroke count method yielded closer agreement with oximetry data.

Clinical validation of a radionuclide detector to measure ejection fraction in critically ill patients

The use of a new non-imaging nuclear probe (Cardioscint) capable of continuous online monitoring of left ventricular function is described in critically ill patients undergoing mechanical ventilation. Ejection fraction, measured by the Cardioscint, was compared with that measured by echocardiography. The mean difference was -1.1% (95% confidence interval -2.9 to +0.6%). Mean difference +/- 2 SD was +10.6 to -12.8% (95% confidence intervals +7.5 to 13.6% and -15.8 to -9.0%, respectively). Examples of fluid loading and inotropic support showed comparable changes in stroke counts measured by the Cardioscint and stroke index measured by thermodilution. The Cardioscint is a practical bedside method for continuous or repeated measurement of ejection fraction and for assessing the response to therapeutic interventions in critically ill patients.

Response of left ventricular diastolic filling to graded exercise relative to the lactate threshold.

During incremental exercise, the left ventricular ejection fraction increases up to the intensity of the anaerobic threshold and tends to level off at higher exercise intensities. Since there is a correlation between the response of peak filling rate and ejection fraction to exercise, this study was conducted to determine whether the response of left ventricular diastolic function is similar to the response of systolic function relative to lactate threshold. Twelve healthy men performed two exercise tests on a cycle ergometer. In the first test, lactate threshold and maximal power output were determined. In the second exercise test, gated radionuclide ventriculography was performed at rest, at the lactate threshold intensity, and at peak exercise to measure ejection fraction and peak filling rate. Ejection fraction increased significantly from rest [mean (SD): 62 (5)%] to lactate threshold [76 (7)%] and did not change significantly from lactate threshold to peak exercise [77 (7)%]. Likewise, peak filling rate (normalized for stroke counts) increased from resting [6.1 (0.9) VS.s-1] to lactate threshold [9.4 (1.8) VS.s-1] and did not change significantly from lactate threshold to peak exercise [9.6 (2.9) VS.s-1]. There was no correlation between the change in peak filling rate and the change in ejection fraction from rest to lactate threshold. Thus, during incremental exercise, left ventricular diastolic function responds qualitatively similar to systolic function.

Assessment of Mitral Regurgitation Using Gated Radionuclide Ventriculography: Analysis of Left Atrial Time Activity Curve

The authors analyzed the left atrial (LA) time activity curve (TAC) in 18 normal subjects and 30 patients with mitral regurgitation (MR) to assess the usefulness of radionuclide ventriculography (RNV) in detecting MR. The LA TAC was generated from gated blood pool images using phase and amplitude images. The configuration of normal LA TAC was M shaped. The first peak and last peak of LA TAC were represented as points B and D, respectively. In addition, the trough following B was named point C. The presence and severity of MR was analyzed by use of three methods: (1) analysis of LA TAC, (2) analysis of left ventricular TAC, and (3) measurement of the stroke count ratio of left ventricle to right ventricle. In the diagnosis of MR using RNV, the rapid emptying fraction [REF:(B-C)/(B-A)] of LA TAC was the most sensitive index compared with the other two methods. The sensitivity and specificity of MR with Sellers' II degrees or more were 0.84 and 0.90 in LA TAC but were 0.42 and 0.90 in the count method.