bluuebunny/crossref_metadata_2025 huggingface dataset:
Computerized quantitative analysis of left ventricular wall motion by two-dimensional echocardiography.
Authors: Schnittger I , Fitzgerald P J , Gordon E P , Alderman E L , Popp R L
Published: June 2011

Quantitative detection of left ventricular segmental wall motion abnormalities by any modality depends on the reference system used because of the dynamic geometry of contraction and cardiac motion within the thorax. To assess the feasibility and accuracy of quantitative analysis of left ventricular wall motion by two-dimensional echocardiography, we studied 61 subjects with the use of 44 different reference methods in each of three echocardiographic views: the parasternal short-axis view at the levels of the mitral valve and of the papillary muscles and an apical four-chamber view. The three major groups of reference systems used were those with a fixed external reference, a floating reference correcting for translation, and systems correcting for both translation and rotation. In the first part of this study the end-diastolic and end-systolic outlines of 20 normal subjects were stored in a computer and composite data of these 20 subjects were plotted to obtain a 95% confidence interval for measured normal fractional change for each reference method. In the second part of the project an additional prospective group of 10 normal subjects and a group of 31 "abnormal" patients had their left ventricular wall motion analyzed by similar methods and the results were compared with all the confidence intervals. One reference method was selected for each two-dimensional echocardiographic view based on the highest sensitivity and specificity found by statistical analysis; a floating-reference system including translation was found to be optimal for the apical four-chamber and parasternal short-axis views at the level of the mitral valve and a fixed external reference system was optimal for the short-axis view at the papillary level. The percent fractional shortening of radial dimensions (radial methods) and the percent fractional change in area measurements (area methods) during the cardiac cycle were also calculated at 5, 10, 20, 30 and 45 degree intervals around the outline perimeter for each subject according to each of the 44 different methods. Area methods yielded the same specificity and sensitivity as radial dimension analysis methods at 5 to 45 degree intervals. Ten normal subjects underwent repeat echocardiography within 2 days of their first study to examine day-to-day variation. Average change in mean contraction from day to day was 7% to 9% for radial methods and 9% to 13% for area methods. In conclusion, we present a computerized system for unbiased selection of optimal methods of analysis of left ventricular wall motion by two-dimensional echocardiography.(ABSTRACT TRUNCATED AT 400 WORDS)
The effect of streptokinase on intramyocardial hemorrhage, infarct size, and the no-reflow phenomenon during coronary reperfusion.
Authors: Kloner R A , Alker K J
Published: June 2011

The purpose of this study was to determine whether streptokinase exacerbates intramyocardial hemorrhage during coronary reperfusion, has any intrinsic effect on myocardial infarct size other than its ability to lyse proximal thrombi in coronary arteries, and can abolish the no-reflow phenomenon. Anesthetized open-chest dogs underwent coronary occlusion for 3 hr followed by 3 hr of reperfusion. Area of infarct was assessed by tetrazolium staining, anatomic zone of no-reflow by injection of the fluorescent dye thioflavin S at the end of the reperfusion period, regional blood flow during occlusion and reperfusion by the radioactive microsphere technique, and extent of gross hemorrhage by assessment of photographic enlargements of the heart slices. Area of infarction of the left ventricle was similar in control (13.4 +/- 3.6%) and streptokinase-treated dogs (13.0 +/- 2.9%; p = NS). Seven of eight dogs in the untreated group had anatomic perfusion defects as assessed by thioflavin S at the end of the reperfusion phase; seven of eight dogs in the streptokinase group had anatomic perfusion defects. There was no difference in the extent of gross hemorrhage between the two groups (6.5 +/- 2.1% of left ventricle in controls and 5.7 +/- 2.3% in streptokinase-treated dogs). Severe depression of regional blood flow during reperfusion was present within the infarcted tissue and was associated with an anatomic perfusion defect as defined by thioflavin S; there was moderate depression of flow within the noninfarcted, salvaged subepicardium. In a separate series of experiments, infarcts were assessed for hemoglobin content. Intramyocardial hemoglobin levels were not higher after fibrinolytic therapy plus reperfusion compared with reperfusion alone.(ABSTRACT TRUNCATED AT 250 WORDS)
The effect of left ventricular systolic function on maximal aerobic exercise capacity in asymptomatic patients with coronary artery disease.
Authors: Ehsani A A , Biello D , Seals D R , Austin M B , Schultz J
Published: June 2011

The purpose of this study was to examine the relationship between maximal O2 uptake (VO2max) and left ventricular systolic function in patients with coronary artery disease. We studied 27 patients, age 50 +/- 10 years (mean +/- SD), who were asymptomatic and able to attain true VO2max. VO2max was defined by the leveling-off criterion and/or a respiratory exchange ratio of 1.15 or greater. Left ventricular ejection fraction was determined by gated cardiac blood pool imaging. In patients whose ejection fraction decreased with exercise, VO2max was 21 +/- 4 vs 27 +/- 4 ml/kg/min in those whose ejection fraction increased (p less than .001). Systolic blood pressure/end-systolic volume relation was shifted upward and to the right in the former group in response to peak exercise. In contrast, the pressure-volume relation was shifted upward and to the left in patients whose ejection fraction increased with exercise. Ejection fraction at rest did not correlate with VO2max. There was a significant but weak correlation between peak exercise ejection fraction and VO2max (r = .43, p less than .025). Left ventricular exercise reserve, i.e., the change in ejection fraction from rest to exercise, correlated with VO2max (r = .77, p less than .0002), maximal O2 pulse (r = .50, p less than .005), and maximal heart rate during treadmill exercise (r = .61, p less than .001). Maximal heart rate during treadmill exercise correlated with VO2max (r = .70, p less than .0002).(ABSTRACT TRUNCATED AT 250 WORDS)
Primary pulmonary hypertension: natural history and the importance of thrombosis.
Authors: Fuster V , Steele P M , Edwards W D , Gersh B J , McGoon M D , Frye R L
Published: June 2011

A long-term retrospective follow-up study was made of 120 patients (33 male, 87 female patients) with primary pulmonary hypertension--diagnosed by strict clinical and hemodynamic criteria--to obtain a better understanding of the natural history and possible pathogenetic mechanisms of the disease. The mean age at diagnosis was 34 (3 to 64) years, but only 24 patients (21%) remained alive 5 years later. Lung tissue obtained at autopsy from 56 patients revealed two major pathologic types: thromboembolic pulmonary hypertension in 32 patients (57%) and plexogenic pulmonary arteriopathy in 18 (32%). Thus, in more than half the patients undergoing autopsy the major histologic feature was thrombi without any evidence of plexiform lesions. The two groups were similar with respect to their clinical and hemodynamic features and short survival. Of the variables tested for prognostic importance by stepwise multivariate analysis, only two were significant: pulmonary arterial oxygen saturation (p less than .00001) and anticoagulant therapy (p = .01). Anticoagulant therapy is recommended for patients with primary pulmonary hypertension.
Intravenous infusion of a selective inhibitor of thromboxane A2 synthetase in man: influence on thromboxane B2 and 6-keto-prostaglandin F1 alpha levels and platelet aggregation.
Authors: Yui Y , Hattori R , Takatsu Y , Nakajima H , Wakabayashi A , Kawai C , Kayama N , Hiraku S , Inagawa T , Tsubojima M
Published: June 2011

The effect of the selective thromboxane A2 synthetase inhibitor OKY-1581, a pyridine derivative [sodium (E)-3-(4-(3-pyridylmethyl)phenyl)-2-methyl-2-propenoate], on thromboxane B2 and 6-keto-prostaglandin F1 alpha levels and platelet aggregation was studied in human volunteers. To clarify its effectiveness as an enzyme inhibitor, OKY-1581, at doses of 17, 83, 167, 417, 833, and 1667 micrograms/kg (n = 5 for each group), was injected intravenously, or was infused (10 micrograms/kg/min; n = 5) over 3 hr on 3 successive days. OKY-1580 (OKY-1581 free acid) was rapidly converted to its main beta-oxidized product, OKY-1565, and its reduced form, OKY-1558. During the study, plasma thromboxane B2 levels, inhibition of thromboxane B2 production in serum, and inhibition of rabbit platelet thromboxane A2 synthetase were monitored continuously. Twenty-five minutes after the injection of the above doses, plasma thromboxane B2 levels decreased by 4 +/- 7%, 40 +/- 14%, 57 +/- 7%, 68 +/- 6%, 93 +/- 5%, and 96 +/- 5% (mean +/- SD), respectively. Thromboxane B2 production in serum was decreased by 2 +/- 8%, 70 +/- 10%, 75 +/- 8%, 81 +/- 10%, and 96 +/- 8%, respectively, and rabbit platelet thromboxane A2 synthetase by 2 +/- 7%, 52 +/- 8%, 79 +/- 10%, 80 +/- 9%, 96 +/- 8%, and 95 +/- 7%. These parameters returned to the control levels 24 hr after the injection.(ABSTRACT TRUNCATED AT 250 WORDS)
Subendocardial resection for ventricular tachycardia: predictors of surgical success.
Authors: Miller J M , Kienzle M G , Harken A H , Josephson M E
Published: June 2011

We retrospectively evaluated the first 100 patients who underwent mapping-guided subendocardial resection (SER) at our hospital for drug-refractory sustained ventricular tachycardia caused by coronary artery disease. There were 91 survivors of surgery with 200 morphologically distinct types of ventricular tachycardia. Eighty-three patients (91%) were cured of ventricular tachycardia by SER alone (60 patients or 66%) or by SER in combination with antiarrhythmic drug therapy (23 patients or 25%) (mean follow-up, 28 +/- 19 months). There were four late sudden deaths and four patients continued to have rare episodes of spontaneous ventricular tachycardia after surgery despite receiving antiarrhythmic drugs. Factors associated with failure of SER alone to cure ventricular tachycardia were presence of disparate sites of ventricular tachycardia origin (greater than 5 cm between mapped sites of origin; 64% vs 30% failure rate) and presence of multiple morphologically distinct spontaneous tachycardias (47% vs 25% failure rate). A log-linear model of multivariate analysis identified disparate sites of origin of ventricular tachycardia and the absence of a discrete left ventricular aneurysm as the only independent variables associated with failure of surgery alone. Inferior wall site of origin (41% vs 12% failure) and right bundle branch block morphology of ventricular tachycardia (20% vs 7% failure) were also significantly associated with failure of surgery to cure ventricular tachycardia. Mapping-guided SER is a highly effective mode of treatment for drug-refractory ventricular tachycardia, despite the existence of subgroups of patients with higher-than-average surgical failure rates.
Magnetic resonance imaging: evaluation of palliative systemic-pulmonary artery shunts.
Authors: Jacobstein M D , Fletcher B D , Nelson A D , Clampitt M , Alfidi R J , Riemenschneider T A
Published: June 2011

Eleven patients with a total of 17 palliative systemic-pulmonary artery shunts underwent evaluation by electrocardiogram-gated magnetic resonance imaging (GMRI). GMRI successfully imaged 11 of 17 shunts (65%), including five of nine Blalock-Taussig shunts, four of six Glenn shunts, and both aortopulmonary shunts. All shunts except for the Waterston were imaged on coronal sections during end-systole. The single Waterston shunt was seen on sagittal and transverse scans. Shunt localization and identification were facilitated by obtaining multiple, contiguous sections through the body. Glenn shunts could be imaged entirely in one section, although multiple sections were required to locate the correct plane. Blalock-Taussig shunts generally required multiple sections to image different segments of the shunt. Both aortopulmonary shunts were seen as direct side-to-side connections of the aorta and pulmonary artery. GMRI permitted assessment of the size, course, patency, and distribution of systemic-pulmonary artery shunts as well as the size and morphology of the proximal pulmonary arteries. We conclude that GMRI is a useful, noninvasive method for imaging the anatomy of systemic-pulmonary artery shunts.
Comparison between intracellular and extracellular direct current recordings of sinus node activity for evaluation of sinoatrial conduction time.
Authors: Haberl R , Steinbeck G , Lüderitz B
Published: June 2011

For evaluation of sinoatrial conduction time in humans, study of extracellular direct current (DC) electrograms from the sinus node has been proposed. To validate this method, we compared transmembrane potentials from multiple sites (40 to 60, "mapping" of sinoatrial activation by microelectrode technique) and extracellular DC electrograms of the sinus node in 12 isolated rabbit atria. Sinoatrial conduction time, measured by microelectrodes and by extracellular electrograms, was essentially the same if the DC electrode was positioned over the pacemaker center (35 +/- 15 and 33 +/- 15 msec, respectively; deviation less or equal to 2 msec). While in all experiments phase 4 and phase 0 depolarization of dominant pacemaker fibers was reflected in the DC electrogram, it shape was influenced by pacemaker location and duration of sinoatrial impulse propagation. If sinoatrial conduction time was long (greater than 25 msec) the transition from the diastolic to the upstroke slope was smooth and the sinus node potential was clearly separated from atrial activity. If sinoatrial conduction time was short (less or equal to 25 msec) the onset of the upstroke slope was well defined and the upstroke slope directly merged into atrial activity. Extracellular recordings 0.2 mm away from the pacemaker center were fairly unchanged in shape; however, sinoatrial conduction time was significantly underestimated. Underestimation also occurred when the tip size of the extracellular electrode was increased from 0.2 to 0.5 and 1.0 mm. Thus sinus node activity is reflected in extracellular DC recordings; however, measurement of sinoatrial conduction time by this technique requires exact localization of the electrode over the pacemaker center, which cannot be controlled in humans.
Echocardiographic recognition and implications of ventricular hypertrophic trabeculations and aberrant bands.
Authors: Keren A , Billingham M E , Popp R L
Published: June 2011

The accuracy of two-dimensional echocardiography in the recognition of aberrant ventricular bands and pathologic trabeculations (hypertrophic, fibrotic, or both) was assessed in 35 patients who underwent cardiac transplantation and pathologic examination. At pathologic study the prevalence of specific intracavitary structures ranged from 28% to 43%. Left ventricular thrombi were found in 12 patients (34%) and right ventricular thrombi in three (9%). Echocardiography accurately defined left ventricular aberrant bands and left ventricular thickened or fibrotic trabeculations. Bands, trabeculations, and thrombi each showed characteristic echocardiographic patterns. In the right ventricle, these structures were recognized, but accurate discrimination among them was not possible by echocardiography. Aberrant bands and pathologic trabeculations mimicked or obscured fresh or organized thrombi in three patients on two-dimensional echocardiography. Left ventricular longitudinal bands and pathologic right ventricular trabeculations obscured the interventricular septal border in four patients; the presence of these abnormalities could lead to the erroneous diagnosis of asymmetric septal hypertrophy on M mode echocardiography. By expressing the accuracy of two-dimensional echocardiography in the recognition of left ventricular anomalous bands, our results support the feasibility of prospective studies to clarify their clinical significance.
Salutary effects of intravenous ajmaline in patients with paroxysmal supraventricular tachycardia mediated by dual atrioventricular nodal pathways: blockade of the retrograde fast pathway.
Authors: Sethi K K , Jaishankar S , Gupta M P
Published: June 2011

Electrophysiologic effects of 50 mg iv ajmaline were evaluated in 10 patients with atrioventricular nodal reentrant paroxysmal supraventricular tachycardia (PSVT) utilizing the slow pathway for antegrade and the fast pathway for retrograde conduction. Ajmaline terminated the PSVT in all 10 patients in 17 to 165 sec (mean 94 +/- 49 sec): by ventriculoatrial block in eight, AH block in one, and intra-atrial reentry in one patient. The predrug mean PSVT cycle length of 289 +/- 44 msec (range 240 to 350) increased significantly to 373.5 +/- 60 msec (range 263 to 464; p less than .01) before the tachycardia was terminated. The increase in cycle length was a function of both AH and HA prolongation. In all 10 patients ajmaline depressed conduction through the retrograde fast pathway, as evidenced by the increase in mean ventricular paced cycle length producing ventriculoatrial block from less than or equal to 280 +/- 40 to 438 +/- 93 msec (p less than .001), and the increase in the effective refractory period of the ventriculoatrial conduction system from less than or equal to 241 +/- 42 to less than or equal to 298 +/- 62 msec (p less than .05); the drug abolished ventriculoatrial conduction in four cases. The effective refractory period of the antegrade fast pathway was unchanged after ajmaline (less than or equal to 281 +/- 31 vs less than or equal to 275 +/- 38 msec; p = NS), but conduction through the antegrade slow pathway was depressed (atrial paced cycle length producing AH block 269 +/- 30 msec before and 312 +/- 44 msec after drug; p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
Anatomic correction of transposition of the great arteries associated with ventricular septal defect: midterm results in 50 patients.
Authors: Bical O , Hazan E , Lecompte Y , Fermont L , Karam J , Jarreau M M , Tran Viet T , Sidi D , Leca F , Neveux J Y
Published: June 2011

From May 1977 to August 1982 50 patients who were 1.5 to 44 months old underwent anatomic correction of transposition of the great arteries (TGA) and closure of ventricular septal defect (VSD) at our institution. Thirty-nine patients underwent preliminary pulmonary arterial banding. Hospital mortality was 32%: four patients died as a result of technical problems, seven as a result of associated lesions, three of pulmonary hypertension, and two of left ventricular failure. Three other patients died after the first postoperative month (one of mediastinitis, one at reoperation for a residual VSD, and one of pulmonary hypertension). All 31 survivors are in excellent clinical condition and are in sinus rhythm after a mean follow-up period of 31 +/- 14 months. Twenty-five patients were reinvestigated by echocardiography (M mode and two-dimensional) and/or catheterization. Parameters of left ventricular contractility were within normal limits, but systolic aortic diameter was larger than normal (p less than .01). Seven patients had stenosis of the right ventricular outflow tract and five of these required reoperation. The two persistent problems with the anatomic correction of TGA associated with VSD are a relatively high operative mortality and secondary right outflow tract stenosis. However, use of this procedure results in better left ventricular function and fewer arrhythmias than does use of atrial repair techniques and also results in the use of the anatomically left ventricle as the systemic ventricle.
Increased vasoconstrictor activity of proximal coronary arteries with endothelial damage in intact dogs.
Authors: Brum J M , Sufan Q , Lane G , Bove A A
Published: June 2011

In this study we examined the hypothesis that endothelial damage increases proximal coronary arterial vasomotor tone and sensitivity to vasoconstrictor stimulation. The response of the left anterior descending coronary artery (LAD) (% area change) to serotonin and nitroglycerin were examined in eight anesthetized (Innovar + nitrous oxide), closed-chest dogs by means of quantitative coronary angiography. Dose-response curves of percent change in arterial cross-sectional area for three doses of intracoronary serotonin were examined before and after endothelial damage produced by a balloon catheter in the LAD. Endothelial damage was verified by postmortem scanning electron microscopic examination. Intracoronary injection of 133Xe provided coronary flow data. The damaged segment of LAD showed spontaneous vasoconstriction and further constriction in response to serotonin (33 +/- 5% before and 52 +/- 6% area reduction after damage; p less than .05). Nitroglycerin reversed serotonin-induced vasoconstriction in LAD segments without damage but not in the LAD segment with endothelial damage. No significant changes were observed in aortic pressure, and heart rate was kept constant by pacing. Blood flow in the LAD was not affected by endothelial damage itself (control, 2.44 +/- 0.09 ml/min/g; damage, 2.53 +/- 0.22 ml/min/g). Endothelial damage induced spontaneous proximal coronary constriction and diminished the relaxant response to nitroglycerin in the presence of serotonin. These results suggest that focal coronary narrowing that occurs in some patients after provocation with vasoconstrictor agents may be caused by local areas of damaged endothelium.
Intraoperative endocardial mapping during sinus rhythm: relationship to site of origin of ventricular tachycardia.
Authors: Kienzle M G , Miller J , Falcone R A , Harken A , Josephson M E
Published: June 2011

Mapping-guided endocardial resection has proved to be an effective therapy for recurrent sustained ventricular tachycardia. However, some patients cannot be mapped during ventricular tachycardia, so that guidance from findings during normal sinus rhythm would be highly desirable. We examined the frequency, timing, and duration of several abnormal types of electrograms recorded endocardially during sinus rhythm and related these findings to activation mapping during sustained ventricular tachycardia. Thirteen patients with extensive myocardial infarction complicated by recurrent sustained ventricular tachycardia were studied intraoperatively during sinus rhythm and induced ventricular tachycardia with a standardized mapping scheme involving the entire endocardial surface. Fractionated electrograms (multicomponent with amplitude less than 1 mV and duration greater than 50 msec) were recorded in all patients. This type of electrogram could be recorded at up to 36% of mapped sites. Split electrograms (two components separated by isoelectric period) were also frequently seen but involved only a mean of 5.8% of mapped sites. Late electrograms (inscribed entirely after the QRS complex) were only recorded in four of 13 patients at a mean of 5% of mapped sites. The location of these electrograms was related to an arbitrary 8 cm2 zone around the earliest site of endocardial activation recorded during ventricular tachycardia. The longest fractionated electrogram was closely related to nine of 22 morphologies of induced ventricular tachycardia, split electrograms were related to seven of 16 morphologies, and late electrograms to two of four morphologies. We have concluded that extremely abnormal electrograms recorded endocardially during sinus rhythm are widespread in patients with extensive myocardial infarction complicated by ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)
Variation of left ventricular myocardial gray level on two-dimensional echocardiograms as a result of cardiac contraction.
Authors: Olshansky B , Collins S M , Skorton D J , Prasad N V
Published: June 2011

Integrated ultrasonic backscatter from normal myocardium has been shown to vary with the phase of cardiac contraction (decreasing from end-diastole to end-systole) in previous studies of open-chest dogs. If confirmed, this finding would have important implications for clinical application of ultrasonic tissue characterization. Our hypothesis was that a cardiac cycle-dependent variation in regional average gray level would be detected on analysis of digitized two-dimensional echocardiograms. We analyzed echocardiographic images from 16 subjects in whom normal, technically good studies were obtained with a commercial phased-array scanner and a 2.25 MHz transducer. Images from six subjects were digitized from stop-frame photographs and those from 10 subjects were obtained directly in digital format from the scanner. Average gray level was measured in a portion of the left ventricular posterior wall in parasternal long-axis images obtained at end-diastole and end-systole by both photographic and digital-image acquisition. In seven of the subjects from whom digital images were acquired, left ventricular posterior wall gray level and ventricular septal gray level were also evaluated on parasternal short-axis images. In images digitized by the photographic technique, mean posterior wall gray level decreased significantly from end-diastole (175 +/- 5.8 SEM) to end-systole (167 +/- 5.1, p less than .05). Similarly, in images digitized directly, mean posterior wall gray level in the long-axis view decreased from end-diastole (71 +/- 3.4) to end-systole (59 +/- 2.5, p less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)
Factors influencing probability of reperfusion with intracoronary ostial infusion of thrombolytic agent in patients with acute myocardial infarction.
Authors: Tendera M P , Campbell W B , Tennant S N , Ray W A
Published: June 2011

A multivariate logistic regression equation was used to evaluate variables related to successful intracoronary thrombolytic therapy. One hundred seventeen patients with a totally occluded infarct-related artery were randomly given ostial infusions of urokinase or streptokinase in a blinded study. The opening rate was 57%. The agent used and time from onset of symptoms to beginning of treatment did not significantly influence opening rate (p greater than .25). The site of occlusion was a strong predictor of opening rate (p = .0004). The anterior descending coronary artery was successfully opened more frequently than the left circumflex or right coronary artery (p = .012). Presence of collaterals adversely affected the recanalization rate in all groups (p = .0004). These variables had an additive effect on the probability of opening. Patients with proximal anterior descending occlusion and no collaterals had a 90% recanalization rate, while those with distal occlusions in vessels other than the anterior descending and with collaterals had only a 24% chance for reperfusion. Thus location of occlusion and presence or absence of collaterals may strongly influence opening rates.
Comparison of Doppler echocardiographic peak frequency and turbulence parameters in the quantification of aortic stenosis in a pulsatile flow model.
Authors: Cannon S R , Richards K L , Morgann R G
Published: June 2011

To test the relative accuracy of Doppler echocardiographic peak frequency and turbulence parameters in assessing aortic stenosis, we constructed a pulsatile flow model that simulated human left ventricular and aortic pressures, flow, and anatomy. Continuous wave-measured peak frequencies and pulsed Doppler-measured turbulence were determined in the model ascending aorta for nine stenotic valve areas for each of five different flow rates. The mean squared systolic peak frequency (MSPF) and turbulence spectral envelope area (SEA) were regressed against the mean systolic gradient (r = .94, SEE = 5.6 mm Hg; and r = .96, SEE = 1.2 mm Hg, respectively). SEA was more accurate than MSPF at moderate-to-high degrees of stenosis and exhibited a smaller standard error. MSPF was more accurate than SEA in mild stenoses, where SEA tended to overestimate gradients. When flow data were included in a multiple regression analysis, both MSPF and SEA provided fair predictions of actual effective valve areas (r = .90 and r = .94, respectively). Use of high pulse-repetition-frequency Doppler echocardiography significantly reduced aliasing problems common to pulsed Doppler techniques.
Assessment of pericardial constraint in dogs.
Authors: Smiseth O A , Frais M A , Kingma I , Smith E R , Tyberg J V
Published: June 2011

To determine the better method of measuring pericardial constraint, pericardial pressure was recorded by a liquid-filled open-ended catheter and a liquid-containing flat balloon in six open-chest anesthetized dogs. Left ventricular pressure was measured by a micromanometer-tipped catheter and left ventricular anteroposterior diameter was measured by sonomicrometry. Left ventricular end-diastolic pressure was raised to 20 +/- 1.7 (mean +/- SD) mm Hg by intravenous saline. Left ventricular diastolic pressure-diameter loops were constructed (1) with incremental amounts of saline (0 to 50 ml) in the resealed pericardium, (2) with several small holes in the pericardium, and (3) with the pericardium widely open. Measured pericardial pressures were compared with what was assumed to be the correct pericardial pressure, i.e., the calculated difference between left ventricular diastolic pressure (at a given left ventricular diameter) before and after opening the pericardium. Pressure recorded by the flat balloon was similar to the calculated pericardial pressure at all pericardial liquid volumes. Pressure recorded by the open-ended catheter, however, was significantly lower (p less than .05) than the calculated pressure unless there was at least 30 ml of liquid in the pericardium. After several holes had been made in the pericardium it still exerted a constraining effect, as shown by a marked rightward or downward shift of the left ventricular diastolic pressure-diameter relationships after completely opening the pericardium. After holes were made in the pericardium pressure recorded by the flat balloon was still similar to the calculated pericardial pressure. However, pressure recorded by the open-ended catheter was significantly (p less than .02) lower than the calculated pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
Effects of age, sex, and body habitus on QRS and ST-T potential maps of 1100 normal subjects.
Authors: Green L S , Lux R L , Haws C W , Williams R R , Hunt S C , Burgess M J
Published: June 2011

Body surface potential maps provide more detailed regional cardiac electrophysiologic information than the standard electrocardiogram. We performed a large-scale study of a normal population to form a comparison base for evaluation of the clinical utility of this technique. We analyzed body surface maps from 1113 normal subjects from 10 to 80 years old to detail map features as a function of age, sex, and body habitus. Maps were analyzed by visual inspection and by a spatial and temporal data reduction technique that allows statistical comparison of map features. On average, both QRS and ST-T potentials decreased with increasing age. Potential pattern distributions remained constant from 10 to 40 years. Beyond age 40, larger numbers of maps from normal subjects showed depolarization patterns consistent with delayed activation of the left anterior fasicle, despite normal 12-lead electrocardiograms. Only minor QRS potential amplitude and distribution differences were noted when male and female subjects were compared within groups of similar age and body habitus. Male subjects consistently showed greater average T potential amplitudes. Slender body habitus was associated with a more horizontal "zero" potential line. In female subjects over age 40 there were more extensive low-level negative potentials recorded over the precordium during the ST segment than in men. This study defines the range of normal body surface potential maps in a large clinically normal population and provides a basis for qualitative and statistical comparison with map features of patients with disease.
The effects of transcutaneous electrical nerve stimulation in patients with severe angina pectoris.
Authors: Mannheimer C , Carlsson C A , Emanuelsson H , Vedin A , Waagstein F , Wilhelmsson C
Published: June 2011

The pain-relieving effects of transcutaneous electrical nerve stimulation (TENS) were investigated in patients with severe angina pectoris first with respect to systemic and coronary hemodynamics and myocardial metabolism during pacing-induced angina and second in a controlled long-term study. Two series of patients with severe angina pectoris (NYHA class III to IV) were studied (13 patients in the pacing study and 23 in the long-term study). In the pacing-induced angina study there was increased tolerance to pacing (142 +/- 23 compared with 124 +/- 20 beats/min tolerated, p less than .001), improved lactate metabolism (2 +/- 36% compared with -18 +/- 43%, p less than .01), and less pronounced ST segment depression (2.3 +/- 1.1 compared with 2.9 +/- 2.6 mm, p less than 0.05) with TENS. In the long study the effects of TENS were measured by means of repeated bicycle ergometer test, frequency of anginal attacks, and consumption of short-acting nitroglycerin. TENS was used regularly for 1 hr three times per day. The TENS treatment group had increased work capacity (637 +/- 308 vs 555 +/- 277 W . min, p greater than .001), decreased ST segment depression (2.3 +/- 1.1 vs 3.6 +/- 1.6 mm, p less than .001), reduced frequency of anginal attacks (p less than .05), and reduced consumption of short-acting nitroglycerin per week (p less than .05) compared with the control group. The observed effects were mainly due to decreased afterload resulting from systemic vascular dilatation.
Early detection of myocardial infarction in conscious dogs by analysis of plasma MM creatine kinase isoforms.
Authors: Hashimoto H , Abendschein D R , Strauss A W , Sobel B E
Published: June 2011

To determine whether myocardial infarction could be detected early after onset by analysis of subforms of the MM isoenzyme (isoforms) of creatine kinase (MM CK) in plasma, we subjected eight conscious dogs to coronary occlusion and quantified isoforms in serial plasma samples by chromatofocusing. The fractions of MMA (isoelectric point [pI] = 7.91), MMB (pI = 7.74), and MMC (pI = 7.51) in plasma samples before coronary occlusion averaged 11.4 +/- 4.8% (SD), 22.3 +/- 5.5%, and 66.3 +/- 9.6% of total MM CK activity. The fraction of MMA, the isoform of MM CK found in myocardium, increased significantly in plasma 1 hr after coronary occlusion, reached a maximum of 49.7 +/- 8.0% in 4.1 +/- 1.3 hr, and returned to baseline in 12.0 +/- 2.3 hr. The fraction of plasma MM CK activity attributable to MMC, an isoform formed slowly in plasma from MMA via MMB as an intermediate, decreased significantly within 1 hr, reached a minimum of 14.0 +/- 4.1% in 4.8 +/- 1.1 hr, and returned to baseline in 13.0 +/- 2.9 hr after coronary occlusion. Total CK activity did not increase significantly until later, i.e., 5 hr after occlusion, and peaked at 1371 +/- 530 IU/liter in 10.9 +/- 1.9 hr. Within the first 4 hr after coronary occlusion, MMA consistently comprised more than 20% of plasma MM CK activity despite insignificant increase of total CK. Changes in isoform proportions were consistent and independent of peak total CK activity and of cumulative CK release over a 10-fold range. Thus initial CK release indicative of infarction is detectable within 1 hr after the onset of ischemia by quantification of plasma MM CK isoforms.
Intrinsic washout rates of thallium-201 in normal and ischemic myocardium after dipyridamole-induced vasodilation.
Authors: Beller G A , Holzgrefe H H , Watson D D
Published: June 2011

Infusion of dipyridamole has been suggested as an alternative to exercise stress for myocardial perfusion imaging for detection of ischemia, but the mechanism and significance of thallium-201 (201Tl) redistribution after administration of dipyridamole are uncertain. If disparate intrinsic cellular efflux rates of 201Tl from normal and relatively underperfused myocardium in response to dipyridamole-induced vasodilation were observed, this could explain delayed 201Tl redistribution. We investigated eht effect of an intravenous infusion of 0.15 mg/kg dipyridamole on the intrinsic myocardial washout rate of 201Tl as measured with a gamma-detector probe after intracoronary injection (50 muCi) of the radionuclide in open-chested anesthetized dogs. In six normal dogs the t 1/2 for intrinsic 201Tl washout from the myocardium was 89 +/- 11 min (SE) at control conditions and became more rapid at 59 +/- 10 min (p = .0001) after dipyridamole. This corresponded to a significant increase in microsphere-determined epicardial (0.95 +/- 0.11 to 2.23 +/- 0.46 ml/min/g; p = .01) and endocardial (0.86 +/- 0.10 to 1.53 +/- 0.27; p = .029) flows. In 12 dogs with a critical coronary stenosis, the 201Tl intrinsic washout rate slowed from 70 +/- 5 to 104 +/- 6 min (p = .0001) after production of the stenosis and slowed even further to 169 +/- 21 min (p = .003) after dipyridamole.(ABSTRACT TRUNCATED AT 250 WORDS)
Kinetics of 13N-ammonia uptake in myocardial single cells indicating potential limitations in its applicability as a marker of myocardial blood flow.
Authors: Rauch B , Helus F , Grunze M , Braunwell E , Mall G , Hasselbach W , Kübler W
Published: June 2011

To study kinetics and principles of cellular uptake of 13N-ammonia, a marker of coronary perfusion in myocardial scintigraphy, heart muscle cells of adult rats were isolated by perfusion with collagenase and hyaluronidase. Net uptake of 13N, measured by flow dialysis, reached equilibrium within 20 sec in the presence of sodium bicarbonate and carbon dioxide (pH 7.4, 37 degrees C). Total extraction, 80 sec after the reaction start, was 786 +/- 159 mumol/ml cell volume. Cells destroyed by calcium overload were unable to extract 13N-ammonia. Omission of bicarbonate and carbon dioxide reduced total extraction to 36% of control. 13N-Ammonia uptake could also be reduced by 50 muM 4,4' diisothiocyanostilbene 2,2' disulfonic acid, by 100 micrograms/ml 1-methionine sulfoximine, and by preincubation with 5 muM free oleic acid. These results indicate that in addition to metabolic trapping by glutamine synthetase, the extraction of 13N-ammonia by myocardial cells is influenced by cell membrane integrity, intracellular-extracellular pH gradient, and possibly an anion exchange system for bicarbonate. For this reason, the uptake of 13N-ammonia may not always provide a valid measurement of myocardial perfusion.
The natural history of regional dysfunction in a canine preparation of chronic infarction.
Authors: Gibbons E F , Hogan R D , Franklin T D , Nolting M , Weyman A E
Published: June 2011

We used a canine preparation of experimental infarction to study the natural course of echocardiographically defined regional wall motion abnormalities in the 6 weeks after acute coronary ligation. Eight dogs underwent serial short-axis echocardiographic evaluation and microsphere blood flow determinations at control, and 30 min, 48 hr, 1 week, 3 weeks, and 6 weeks after acute coronary artery ligation. Wall motion analysis and blood flow calculations were applied to 10 degree radial segments of the left ventricle (short axis) and correlated to the size and extent of infarction as defined histologically at 6 weeks. All animals had at least 50% transmural histologic infarction. The ratio of flow in infarcted tissue vs noninfarcted myocardium fell to 0.40 +/- 0.13 for endocardium and 0.56 +/- 0.13 for epicardium at 30 min after ligation, but recovered to 0.83 +/- 0.15 for endocardium and 1.12 +/- 0.11 for epicardium by 6 weeks. The maximum circumferential extent of abnormal regional wall motion was observed at 48 hr after infarction (mean circumferential extent = 51%), but was resolved to a significant extent by 6 weeks (circumferential extent = 21%, p less than .001). Four animals had virtually normal wall motion by 6 weeks after infarction. Segment-by-segment regional dysfunction correlated highly with the regional transmural reduction in blood flow of 20% )r = .89, p = .0001) for the experiment as a whole, but the echocardiogram tended to underestimate the size of the histologic infarct at 6 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)
Arteriographic predictors of spontaneous improvement in left ventricular function after myocardial infarction.
Authors: Schwartz H , Leiboff R L , Katz R J , Wasserman A G , Bren G B , Varghese P J , Ross A M
Published: June 2011

To better characterize the changes in left ventricular ejection fraction after myocardial infarction, we compared radionuclide ventriculograms obtained acutely and 2 weeks after acute myocardial infarction in 40 patients. These patients underwent angiography within a mean of 4 hr and 20 min after the onset of symptoms of infarction and either received no therapy (32 patients who were control subjects in a thrombolysis trial) or did not experience reperfusion (eight patients) despite receiving streptokinase infusions. In all 40 patients, the change in left ventricular ejection fraction over 2 weeks was small (+2.6%). Patients were then grouped according to the presence or absence of residual flow on their angiograms. Residual flow was considered to be present in 21 patients, in 12 by virtue of subtotal occlusion of the artery supplying the area of infarct and in nine because of well-developed coronary collaterals to the distal infarct artery. Mean change in ejection fraction for patients with residual flow was +6.9 +/- 2.3% vs -2.2 +/- 1.7% for patients without residual flow (p less than .01). Fourteen of 21 (67%) patients with residual flow had a spontaneous rise in ejection fraction of greater than 5%, as compared with two of 19 (11%) patients without residual flow (p less than .01). Time to peak level of creatine kinase (CK) was significantly shorter in the residual flow group (15 vs 23 hr, p less than .01), while the peak level of CK was lower (1550 vs 2220 IU) in these patients. This latter difference did not reach statistical significance (p = .10).(ABSTRACT TRUNCATED AT 250 WORDS)
Alternative diagnostic strategies for coronary artery disease in women: demonstration of the usefulness and efficiency of probability analysis.
Authors: Melin J A , Wijns W , Vanbutsele R J , Robert A , De Coster P , Brasseur L A , Beckers C , Detry J M
Published: June 2011

Alternative strategies using conditional probability analysis for the diagnosis of coronary artery disease (CAD) were examined in 93 infarct-free women presenting with chest pain. Another group of 42 consecutive female patients was prospectively analyzed. For this latter group, the physician had access to the pretest and posttest probability of CAD before coronary angiography. These 135 women all underwent stress electrocardiographic, thallium scintigraphic, and coronary angiographic examination. The pretest and posttest probabilities of coronary disease were derived from a computerized Bayesian algorithm. Probability estimates were calculated by the four following hypothetical strategies: SO, in which history, including risk factors, was considered; S1, in which history and stress electrocardiographic results were considered; S2, in which history and stress electrocardiographic and stress thallium scintigraphic results were considered; and S3, in which history and stress electrocardiographic results were used, but in which stress scintigraphic results were considered only if the poststress probability of CAD was between 10% and 90%, i.e., if a sufficient level of diagnostic certainty could not be obtained with the electrocardiographic results alone. The strategies were compared with respect to accuracy with the coronary angiogram as the standard. For both groups of women, S2 and S3 were found to be the most accurate in predicting the presence or absence of coronary disease (p less than .05). However, it was found with use of S3 that more than one-third of the thallium scintigrams could have been avoided without loss of accuracy. It was also found that diagnostic catheterization performed to exclude CAD as a diagnosis could have been avoided in half of the patients without loss of accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)
A prospective randomized study of the clinical efficacy and safety of transvenous cardioversion for termination of ventricular tachycardia.
Authors: Ciccone J M , Saksena S , Shah Y , Pantopoulos D
Published: June 2011

The clinical efficacy and safety of transvenous cardioversion for termination of sustained ventricular tachycardia (VT) were examined by a prospective randomized study design in 22 patients (19 men, three women; mean age 64 +/- 9 years) with organic heart disease and sustained VT. Patients were randomly assigned to undergo an incremental low-energy protocol from 0.03 to 2.2 J (group A, 11 patients) or an incremental high-energy protocol from 0.5 to 10.0 J (group B, 11 patients). Transvenous cardioversion was performed during electrophysiologic studies in the control (drug-free) state and during serial antiarrhythmic drug testing in all patients. Both groups were comparable for demographic, disease and functional status, and electrophysiologic parameters. A total of 77 episodes of VT (group A, 45; group B, 32) were analyzed. The overall efficacy of transvenous cardioversion for termination of VT was 62% (group A 56% vs group B 72%; p less than .01). Antiarrhythmic drug therapy did not significantly enhance efficacy of transvenous cardioversion (control 59% vs drug 65%; p greater than .2). Stepwise discriminant analysis correlated successful transvenous cardioversion with longer VT cycle length (p less than .0005), higher energy (p less than .025), lower energy waveform tilt (p less than .025), shorter time to initial cardioversion attempt (p less than .025), and shorter QRS duration in sinus rhythm (p less than .05). Acceleration of VT was frequent (8% incidence per delivered shock). Thirty-one percent of all incremental shock protocols were terminated because of this complication. After cardioversion, transient arrhythmias were common (bradyarrhythmias 23%, supraventricular tachyarrhythmias 12%). Displacement of electrode catheters after transvenous cardioversion was uncommon (3%).(ABSTRACT TRUNCATED AT 250 WORDS)