bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relation of plasma lipid and apoprotein levels to progressive intimal hyperplasia after arterial endarterectomy.
Authors: Colyvas N , Rapp J H , Phillips N R , Stoney R , Perez S , Kane J P , Havel R J 
Published: June 2012

BACKGROUND
To examine the relation of plasma lipoproteins to the proliferative response after arterial injury in humans, we examined the plasma lipid, lipoprotein, and apoprotein levels of 20 patients with early recurrent stenosis caused by intimal hyperplasia after carotid endarterectomy. These were compared with 20 controls who had no evidence of recurrent stenosis by duplex ultrasound scanning.

METHODS AND RESULTS
By univariate analysis, the reoperated patients had higher levels of plasma cholesterol (251 versus 225 mg/dl, p less than 0.05), total triglycerides (173 versus 105 mg/dl, p less than 0.03), and low density lipoprotein (LDL) apoprotein B (99.8 versus 77.2 mg/dl, p less than 0.003). The ratio of cholesterol to apoprotein B in LDL was lower in patients with restenosis (p less than 0.04), suggesting LDL of smaller diameter. High density lipoprotein (HDL) cholesterol level was reduced (45 versus 55 mg/dl, p less than 0.01) in patients with restenosis. With statistical adjustment for the correlations between these variables by multivariate analysis, both LDL apoprotein B and HDL cholesterol were independent predictors of the risk of restenosis. Ten patients with restenosis but only two controls had one or two apolipoprotein E4 alleles.

CONCLUSIONS
Elevated lipid levels usually associated with an increased risk of atherosclerosis may predispose patients to an increased incidence of intimal hyperplasia after endarterectomy.
Expanded Clinical Evaluation of Lovastatin (EXCEL) study results. Effect of patient characteristics on lovastatin-induced changes in plasma concentrations of lipids and lipoproteins.
Authors: Shear C L , Franklin F A , Stinnett S , Hurley D P , Bradford R H , Chremos A N , Nash D T , Langendorfer A 
Published: June 2012

BACKGROUND
Lovastatin produces consistent dose-related reductions in plasma levels of low density lipoprotein (LDL) cholesterol along with variable decreases in triglycerides and increases in high density lipoprotein (HDL) cholesterol. Patient characteristics from the Expanded Clinical Evaluation of Lovastatin (EXCEL) study were examined to determine their association with the magnitude of lovastatin-induced changes in these lipids and lipoproteins.

METHODS AND RESULTS
After a baseline period consisting of dietary therapy, 8,245 patients with moderate hypercholesterolemia were randomized to five groups that received 48 weeks of treatment with either placebo or daily doses of lovastatin ranging from 20 to 80 mg. By use of linear statistical models, 20 different patient characteristics were examined for modification of the dose-dependent responses observed. For LDL cholesterol, the following were associated with enhanced lowering (p less than 0.05; percent changes are placebo-corrected, adjusted mean changes from baseline for the 80-mg/day lovastatin group): full drug compliance (-41.9%) versus 80% compliance (-20.3%); an age of 65 (-43.4%) versus 45 years (-38.1%) for women; white race (-40.9%) versus black race (-38.0%); and 4.5-kg weight gain (-42.6%) versus 4.5-kg weight loss (-37.9%). Similar relations for enhanced triglyceride lowering were found with older age and weight gain. Patients with initially low HDL cholesterol (less than 0.91 mmol/l) and high triglycerides (greater than 2.26 mmol/l) had enhanced responses for these parameters: placebo-corrected percent changes at 80 mg/day were -27.4% for triglycerides and +12.3% for HDL cholesterol.

CONCLUSIONS
Overall, patient characteristics had very little impact of clinical importance on the dose-dependent LDL cholesterol lowering found with lovastatin. In patients with initially high levels of triglycerides and low levels of HDL cholesterol, the elevation of HDL cholesterol produced by lovastatin appears to be enhanced.
Continuous measurement of left ventricular performance during and after maximal isometric deadlift exercise.
Authors: Sullivan J , Hanson P , Rahko P S , Folts J D 
Published: June 2012

BACKGROUND
Isometric exercise produces a reflex increase in arterial blood pressure that is proportional to the intensity and mass of muscle used during contraction. Little is known about the transient effects of heavy weight lifting on left ventricular performance. In this study, we measured continuous changes in left ventricular performance during maximal large-muscle isometric exercise using the standing deadlift position.

METHODS AND RESULTS
Ten healthy young men performed serial deadlifts at 50% of maximal voluntary effort for 90 seconds and 100% of maximal effort for 30 seconds. Echocardiographic imaging (apical four-chamber view), arterial blood pressure (brachial artery catheter), and electrocardiographic monitoring were recorded throughout the deadlift and for 30 seconds of recovery. Aortic flow velocity was also monitored during a separate series of deadlifts. During 100% maximal deadlift, mean arterial pressure increased from 108 +/- 4 to 164 +/- 6 mm Hg. Left ventricular ejection fraction declined initially (from 57 +/- 2% to 49 +/- 3%) at 15 seconds into the lift and recovered (56 +/- 1%) due to significant increases in end-diastolic volume (104 +/- 11 ml to 132 +/- 16 ml) by the end of the lift. The peak systolic pressure/end-systolic volume ratio did not change during the deadlift. After cessation of the deadlift, mean arterial pressure declined precipitously (to 88 +/- 4 mm Hg) within 5 seconds and gradually returned to baseline after 30 seconds. Left ventricular performance indexes all increased significantly during the recovery phase (ejection fraction to 68 +/- 3%, peak systolic pressure/end-systolic volume ratio to 5.9 +/- 0.9). Findings were qualitatively similar for the 50% deadlift.

CONCLUSIONS
During an intense isometric deadlift, left ventricular performance declines initially but is restored by the Frank-Starling mechanism. Upon release of the deadlift, increased left ventricular performance develops in conjunction with a rapid decrease in arterial pressure. The combined effects of increased wall stress during the lift phase and enhanced contractility during the release phase probably contribute to left ventricular hypertrophy associated with repetitive weight training.
Ultrafast computed tomography analysis of regional radius-to-wall thickness ratios in normal and volume-overloaded human left ventricle.
Authors: Feiring A J , Rumberger J A 
Published: June 2012

BACKGROUND
This study tested two hypotheses: 1) regional left ventricular radius-to-wall thickness ratios (R/T) are uniform in normal subjects, and 2) patients with left ventricular hypertrophy secondary to compensated volume overload normalize global and regional R/T.

METHODS AND RESULTS
Ultrafast computed tomography was used to measure regional short-axis ventricular R/T in 11 normal subjects and 13 patients with compensated aortic insufficiency (AI) of moderate severity (regurgitant fraction, greater than or equal to 25%). Radius and wall thickness dimensions were calculated by two different methods. In method 1, the average radius and wall thickness were determined for each planimetric transaxial tomographic image. In method 2, the left ventricle was three-dimensionally reconstructed; then, new radii and wall thickness were recalculated as if all the images were acquired orthogonal to the endocardial surface at each tomographic level. In normals, the mean R/T ratio was 1.75 +/- 0.11 (SEM) with method 1 and 1.80 +/- 0.07 with method 2. The R/T ratios varied as a function of the relative apex-to-base position. R/T ratios at the basal four levels were relatively uniform, whereas R/T at the lower three tomographic levels were significantly less than those at the base (p less than 0.01). Patients with AI had a mean regurgitant fraction of 44 +/- 3.8% (range, 25-63%). The mean R/T ratio was 2.18 +/- 0.16 with method 1 and 2.55 +/- 0.18 with method 2. Similar to the pattern observed in normals, the regional R/T ratios at the lower three or four levels were significantly less than the basal R/T ratios (p less than 0.01). Regional comparison of the normal to the volume-overloaded ventricles demonstrated that R/T ratios in the AI patients were significantly greater at the upper five levels with method 1 and at all eight levels with method 2 (p less than 0.01-0.001, AI versus normal).

CONCLUSIONS
These findings demonstrate that regional R/T ratios are heterogeneous in both normals and patients with left ventricular hypertrophy secondary to compensated aortic insufficiency. Furthermore, these findings challenge the accepted hypothesis that global and regional R/T ratios normalize in patients with compensated volume-overload hypertrophy.
Effect of chronic rapid ventricular pacing on total vascular capacitance.
Authors: Ogilvie R I , Zborowska-Sluis D 
Published: June 2012

BACKGROUND
Rapid right ventricular pacing (RRVP) at 250 bpm for 3-6 weeks produces chronic heart failure manifested by a reduction in cardiac output and increases in right atrial, pulmonary artery, and capillary wedge pressures.

METHODS AND RESULTS
One week after splenectomy and pacemaker placement, vascular capacitance, unstressed volume, and compliance were determined in 19 anesthetized dogs from pressure-volume curves using transient circulatory arrests induced by acetylcholine. Nine dogs were restudied 31 +/- 1 days later without RRVP, and 10 dogs underwent RRVP at 250 bpm and were restudied at 23 +/- 8 and 38 +/- 8 days in cardiac failure and after 1 and 2 weeks of postpacing recovery. Control animals had no changes in vascular capacitance or compliance. Dogs undergoing RRVP exhibited a marked increase in mean circulatory filling pressure (5.4 +/- 0.4 to 10.5 +/- 1.5 mm Hg) during the development of cardiac failure with a reduction in unstressed volume (81.9 +/- 5.7 to 43.9 +/- 8.1 ml.kg-1) without changing total vascular compliance. Total blood volume decreased (95.4 +/- 6.2 to 66.7 +/- 6.5 ml.kg-1) primarily due to a reduction in packed cell volume. The pressure gradient for venous return and overall venous resistance was unaltered. Central blood volume as a proportion of total blood volume increased (9.3 +/- 1.7% to 16.0 +/- 2.7%). Arterial compliance and capacity and pulmonary vascular compliance were reduced. In the 2-week postpacing period, except for a reduced cardiac response to a volume load, all of these parameters returned to baseline values.

CONCLUSIONS
Chronic RRVP induced cardiac failure with a marked reduction in total vascular capacitance due to a reduction in unstressed volume without altering compliance. The rise in mean circulatory filling pressure was limited by a reduction in total blood volume.
Selective radiofrequency ablation of the slow pathway for the treatment of atrioventricular nodal reentrant tachycardia. Evidence for involvement of perinodal myocardium within the reentrant circuit.
Authors: Kay G N , Epstein A E , Dailey S M , Plumb V J 
Published: June 2012

BACKGROUND
The circuit of atrioventricular (AV) nodal reentrant tachycardia may include perinodal atrial myocardium. Furthermore, in patients with dual AV nodal pathways, the atrial insertion of the slow pathway is likely to be located near the ostium of the coronary sinus, caudal to the expected location of the AV node. The present study was designed to evaluate the safety and efficacy of selective catheter ablation of the slow pathway using radiofrequency energy applied along the tricuspid annulus near the coronary sinus ostium as definitive therapy for AV nodal reentrant tachycardia.

METHODS AND RESULTS
Among 34 consecutive patients who were prospectively enrolled in the study, the slow pathway was selectively ablated in 30, and the fast pathway was ablated in four. Antegrade conduction over the fast pathway remained intact in all 30 patients after successful selective slow pathway ablation. There was no statistically significant change in the atrio-His interval (68.5 +/- 21.8 msec before and 69.6 +/- 23.9 msec after ablation) or AV Wenckebach rate (167 +/- 27 beats per minute before and 178 +/- 50 beats per minute after ablation) after selective ablation of the slow pathway. However, the antegrade effective refractory period of the fast pathway decreased from 348 +/- 94 msec before ablation to 309 +/- 79 msec after selective slow pathway ablation (p = 0.005). Retrograde conduction remained intact in 26 of 30 patients after selective ablation of the slow pathway. The retrograde refractory period of the ventriculo-atrial conduction system was 285 +/- 55 msec before and 280 +/- 52 msec after slow pathway ablation in patients with intact retrograde conduction (p = NS). There were three complications in two patients, including an episode of pulmonary edema and the development of spontaneous AV Wenckebach block during sleep in one patient after slow pathway ablation and the late development of complete AV block in another patient after fast pathway ablation. Over a mean follow-up period of 322 +/- 73 days, AV nodal reentrant tachycardia recurred in three patients, all of whom were successfully treated in a second ablation session.

CONCLUSIONS
Radiofrequency ablation of the slow AV pathway is highly effective and is associated with a low rate of complications.
Light chain 2 profile and activity of human ventricular myosin during dilated cardiomyopathy. Identification of a causal agent for impaired myocardial function.
Authors: Margossian S S , White H D , Caulfield J B , Norton P , Taylor S , Slayter H S 
Published: June 2012

BACKGROUND
A number of parameters reflecting the effects of idiopathic dilated cardiomyopathy (IDC) on the structure and function of myosin from the human myocardium were analyzed.

METHODS AND RESULTS
The content of the regulatory light chain, LC2, was reduced in myopathic heart myosin in contrast to the controls in which it was present in stoichiometric amounts relative to the essential light chain, LC1. In IDC hearts, the absence or significant reduction in amount of LC2 was related to the presence of an active protease, which was isolated and purified about 130-fold. The protease exhibited a significant degree of specificity: It cleaved LC2 almost totally (but not the heavy chains) in human control heart myosin but only partially cleaved LC2 in canine heart or in rabbit skeletal muscle myosins. The protease was present at a very low level or was inactive in control heart tissue. When the LC1/LC2 molar ratio was calculated, it was found to be 1:1.0 in control heart myosin and remained constant in various samples analyzed, whereas in myopathic myosin from different individuals, this ratio varied from 1:0.1 to 1:0.69. The rates of ATP binding to control and myopathic myosins were similar, whereas the Vm of actin-activated ATPase of myopathic myosin was about 25% less than that of the control. However, ATP binding and its hydrolysis by control S1, i.e., the myosin head, were faster by a factor of 2 than that of the myopathic S1. In addition, control myosin synthetic thick filament length as well as turbidity in solution, measured by light scattering, were twice as large as those of the myopathic heart myosin. These effects induced by myopathy in both filament assembly and turbidity were reversed upon reassociation of IDC myosin with LC2.

CONCLUSIONS
The changes in myosin structure and function were linked to a protease-mediated cleavage of LC2 in myosin; a possible role for the protease in the degenerative effects of idiopathic dilated cardiomyopathy is thus defined.
Coronary calcification and its relation to extracoronary atherosclerosis in asymptomatic hypercholesterolemic men. The PCV METRA Group.
Authors: Megnien J L , Sene V , Jeannin S , Hernigou A , Plainfosse M C , Merli I , Atger V , Moatti N , Levenson J , Simon A 
Published: June 2012

BACKGROUND
The prevalence of coronary calcifications and extracoronary plaques was studied in patients with asymptomatic hypercholesterolemia.

METHODS AND RESULTS
Ultrafast computed tomography for coronary calcification (presence or absence: calcium score) and echographic assessment of carotid, aortic, and femoral plaques were performed in 111 hypercholesterolemic men: 65% had coronary calcification, 72% had extracoronary plaque. The two lesions were associated as: 1) compared with subjects without coronary calcification, those with calcification had a higher prevalence of aortic (p less than 0.05) and femoral (p less than 0.01) plaque and of two diseased sites (p less than 0.05); 2) the prevalence of coronary calcification was higher in the presence than in the absence of aortic (p less than 0.05) or femoral (p less than 0.01) plaque and higher in two (p less than 0.01) and three diseased (p less than 0.05) sites than in no diseased site; 3) the calcium score was higher in the presence than in the absence of carotid (p less than 0.05), aortic (p less than 0.05), or femoral (p less than 0.001) plaque, higher in two (p less than 0.001) and three diseased (p less than 0.05) sites than in no diseased sites, and higher in two (p less than 0.01) than in one diseased site; and 4) the calcium score correlated with femoral plaque (p less than 0.001). Overall, the presence of two or three diseased extracoronary sites versus no or one diseased site showed a power of 78% for predicting coronary calcification. Coronary calcium score correlated with age (p less than 0.01) and triglycerides (p less than 0.05).

CONCLUSIONS
The close relation between coronary calcium and extracoronary plaques suggests that echography of extracoronary vessels could aid in the screening of coronary atherosclerosis in high-risk, asymptomatic individuals.
Spectral analysis of 87-lead body surface signal-averaged ECGs in patients with previous anterior myocardial infarction as a marker of ventricular tachycardia.
Authors: Hosoya Y , Kubota I , Shibata T , Yamaki M , Ikeda K , Tomoike H 
Published: June 2012

BACKGROUND
There were few studies on the relation between the body surface distribution of high- and low-frequency components within the QRS complex and ventricular tachycardia (VT).

METHODS AND RESULTS
Eighty-seven signal-averaged ECGs were obtained from 30 normal subjects (N group) and 30 patients with previous anterior myocardial infarction (MI) with VT (MI-VT[+] group, n = 10) or without VT (MI-VT[-] group, n = 20). The onset and offset of the QRS complex were determined from 87-lead root mean square values computed from the averaged (but not filtered) ECG waveforms. Fast Fourier transform analysis was performed on signal-averaged ECG. The resulting Fourier coefficients were attenuated by use of the transfer function, and then inverse transform was done with five frequency ranges (0-25, 25-40, 40-80, 80-150, and 150-250 Hz). From the QRS onset to the QRS offset, the time integration of the absolute value of reconstructed waveforms was calculated for each of the five frequency ranges. The body surface distributions of these areas were expressed as QRS area maps. The maximal values of QRS area maps were compared among the three groups. In the frequency ranges of 0-25 and 150-250 Hz, there were no significant differences in the maximal values among these three groups. Both MI groups had significantly smaller maximal values of QRS area maps in the frequency ranges of 25-40 and 40-80 Hz compared with the N group. The MI-VT(+) group had significantly smaller maximal values in the frequency ranges of 40-80 and 80-150 Hz than the MI-VT(-) group. These three groups were clearly differentiated by the maximal values of the 40-80-Hz QRS area map.

CONCLUSIONS
It was suggested that the maximal value of the 40-80-Hz QRS area map was a new marker for VT after anterior MI.
Functional significance of collateral blood flow in patients with recent acute myocardial infarction. A study using myocardial contrast echocardiography.
Authors: Sabia P J , Powers E R , Jayaweera A R , Ragosta M , Kaul S 
Published: June 2012

BACKGROUND
We hypothesized that myocardial contrast echocardiography (MCE) can be used to both measure collateral blood flow as well as assess the functional significance of collaterals in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS
MCE was performed in 33 patients with recent AMI (12 +/- 7 days) and an occluded infarct-related artery (IRA), both before and after attempted percutaneous transluminal coronary angioplasty (PTCA). The size of the occluded bed was defined in patients with successful PTCA by injecting contrast directly into the opened IRA and expressed as a percent of the myocardium in the short-axis view. The percent of the perfusion bed supplied by collaterals before PTCA was determined. Transit rates of the microbubbles within the collateralized regions were also measured and were expressed as a percent of the transit rates in the normal adjacent beds. Regional function within the occluded bed was assessed using echocardiography and was graded as 1 (normal) to 5 (dyskinetic). Collaterals were graded on coronary angiography as 0 (none) to 3 (abundant). The perfusion bed size was larger for the left anterior descending (LAD) than for the right (RCA) and left circumflex (LCx) coronary arteries (37 +/- 6% versus 27 +/- 12% of the myocardium, p = 0.02). The percent of the occluded bed supplied by collateral flow was greater for RCA and LCx compared with the LAD (87 +/- 30% versus 72 +/- 22%, p less than 0.01). There was poor correlation between MCE-defined percent of occluded bed supplied by collaterals and angiographic collateral grade (r = 0.13). Regions supplied by collaterals were less likely to show confluent hypoperfused zones after reperfusion compared with those not supplied by collaterals. Similarly, the percent of myocardium not perfused by either anterograde or collateral flow correlated well (r = 0.67, p less than 0.01) with peak creatine kinase levels and was more likely to be associated with Q waves. Finally, although there was poor correlation between angiographic collaterals and regional function (r = 0.20), there was a significant negative correlation between MCE-defined spatial extent of collateral flow and regional function (r = -0.57, p less than 0.01).

CONCLUSION
MCE can be used to measure collateral flow in patients with recent AMI and to assess the functional significance of collaterals in these patients. This technique may be ideally suited for the assessment of collateral perfusion in patients undergoing cardiac catheterization.