bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventricular tachycardia rate and morphology determine energy and current requirements for transthoracic cardioversion.
Authors: Kerber R E , Kienzle M G , Olshansky B , Waldo A L , Wilber D , Carlson M D , Aschoff A M , Birger S , Fugatt L , Walsh S 
Published: June 2012

BACKGROUND
The electrical current and energy required to terminate ventricular tachyarrhythmias are known to vary by arrhythmia: Ventricular tachycardia (VT) is generally considered to require less energy than ventricular fibrillation (VF). The hypothesis of our study was that current requirements for transthoracic termination of VT are further determined by VT rate and QRS complex morphology.

METHODS AND RESULTS
We prospectively studied 203 patients who received a total of 569 shocks for VT or VF by following a current-based protocol. This protocol recommended shocks for VT beginning at 18 A (70 +/- 22 J) and shocks for VF beginning at 25 or 30 A (137 +/- 52 J or 221 +/- 70 J). The ventricular tachyarrhythmias were subclassified as monomorphic VT (MVT): uniform QRS complex morphology on surface electrocardiogram and heart rate greater than 100 beats per minute; polymorphic VT (PVT): nonuniform QRS complex morphology and heart rate less than or equal to 300 beats per minute; or VF: nonuniform QRS complex morphology and heart rate greater than 300 beats per minute. We found that shocks of 18 A and 25 A for terminating MVT had success rates of 69% and 82%, respectively, whereas such low-current shocks were less successful for PVT (33% at 18 A) and for VF (19% at 18 A, 53% at 25 A). High-current shocks of 35 A and 40 A were equally successful for the three ventricular tachyarrhythmias. Subdividing MVT revealed that slower MVT (heart rate less than 200 beats per minute) had a significantly better success rate with low-current shocks of 18 A and 25 A than did faster MVT (greater than 200 beats per minute) (89% versus 72% success, p less than 0.01). Bundle branch block morphology, QRS axis, and duration of ventricular tachyarrhythmia did not alter current requirements.

CONCLUSIONS
Heart rate and electrocardiographic degree of organization of ventricular tachycardia are important determinants of transthoracic energy and current requirements for cardioversion and defibrillation. Transthoracic termination of MVT requires relatively low current or energy, but PVT behaves more like VF and requires higher electrical current or energy.
Trends in survival of hospitalized myocardial infarction patients between 1970 and 1985. The Minnesota Heart Survey.
Authors: McGovern P G , Folsom A R , Sprafka J M , Burke G L , Doliszny K M , Demirovic J , Naylor J D , Blackburn H 
Published: June 2012

BACKGROUND
The Minnesota Heart Survey is a population-based study designed to monitor and explain trends in cardiovascular mortality, morbidity, and risk factors. As part of this effort, a 50% sample of patients hospitalized for myocardial infarction (MI) in the seven-county Twin Cities (Minneapolis and St. Paul) metropolitan area was reviewed in 1970, 1980, and 1985. Those with a validated definite MI were followed for 4-year mortality. The purpose was to determine whether the improved survival observed between 1970 and 1980 was extended to the 1980-1985 period.

METHODS AND RESULTS
Crude 28-day mortality in men changed from 18% in 1970 to 12% in 1980 to 13% in 1985; in women it changed from 27% in 1970 to 22% in 1980 to 18% in 1985. After adjustment for severity factors (e.g., age, previous MI, and admission heart rate and systolic blood pressure), 28-day mortality was significantly lower in 1980 than in 1970 in men (RR, 0.66; 95% CI, 0.47, 0.92) and in women (RR, 0.69; 95% CI, 0.46, 1.04), but no change occurred from from 1980 to 1985 (p greater than 0.25). After adjustment for severity indicators, 4-year survival was better in 1980 than in 1970 for men (RR, 0.67; 95% CI, 0.54, 0.83) and for women (RR, 0.72; 95% CI, 0.54, 0.98), but there was no significant change from 1980 to 1985 (p greater than 0.25).

CONCLUSIONS
These results suggest that improvements in survival among hospitalized MI patients contributed to the overall decline in coronary heart disease mortality in the Twin Cities area between 1970 and 1980 but not between 1980 and 1985.
Lipoprotein profile in men with peripheral vascular disease. Role of intermediate density lipoproteins and apoprotein E phenotypes.
Authors: Sentí M , Nogués X , Pedro-Botet J , Rubiés-Prat J , Vidal-Barraquer F 
Published: June 2012

BACKGROUND
The role of lipoprotein disturbances in the development of peripheral vascular disease (PVD) has not been sufficiently clarified.

METHODS AND RESULTS
The relations among concentrations of intermediate density lipoproteins (IDL), apoprotein (apo) B, apo E, and other lipoproteins were studied in 102 men with PVD and 100 healthy men who formed the control group. Patients with PVD had significantly higher levels of serum triglycerides, very low density lipoprotein (VLDL) cholesterol, VLDL triglycerides, VLDL proteins, IDL cholesterol, and IDL triglycerides and lower levels of high density lipoproteins (HDL) than controls. Serum cholesterol and triglycerides were normal in 30 patients (cholesterol, less than 5.2 mmol/l; triglycerides, less than 2.3 mmol/l), who had significant increases in IDL triglycerides and significant decreases in HDL cholesterol compared with the 47 controls, who had normal cholesterol and triglyceride levels. Patients with more severe distal involvement showed higher cholesterol and triglycerides carried by IDL and a greater reduction in HDL cholesterol. Smoking patients with PVD showed increased VLDL cholesterol and VLDL triglycerides and lower HDL concentrations. Apo E polymorphism in our study population does not differ from that reported for other European populations. Alleles epsilon 2 and epsilon 4 had a major impact on serum triglycerides and VLDL lipids in our patients with PVD.

CONCLUSIONS
Lipoprotein disturbances are a major risk factor for PVD. IDL abnormalities play an important role in the development and severity of PVD and should also be considered a vascular risk factor in normocholesterolemic and normotriglyceridemic patients.
Early postoperative reduction of monoclonal antimyosin antibody uptake is associated with absent rejection-related complications after heart transplantation.
Authors: Ballester M , Obrador D , Carrió I , Moya C , Augè J M , Bordes R , Martí V , Bosch I , Bernà-Roqueta L , Estorch M 
Published: June 2012

BACKGROUND
Detection and treatment for rejection after transplantation are based on the identification of myocyte damage upon endomyocardial biopsy. Noninvasive detection of such damage is possible with 111In-labeled monoclonal antimyosin antibodies (MAA). Although the presence and degree of MAA uptake parallels the rejection activity detected by biopsy, the relation between the degree of uptake and the occurrence of severe rejection-related complications has not been previously assessed.

METHODS AND RESULTS
Two hundred forty-seven MAA studies were performed coinciding with biopsies in 52 patients 1-71 months after transplantation. A heart-to-lung ratio (HLR) was used as a measure of relative MAA uptake, with an HLR of 1.55 discriminating normal from abnormal studies. Of the 247 antimyosin studies, 149 coincided with absent, 38 with mild, and 60 with moderate rejection at biopsy. HLR was 1.68 +/- 0.27, 1.79 +/- 0.22, and 1.91 +/- 0.33 in the three biopsy groups, respectively (p less than 0.0001). Two hundred thirty-eight of 247 antimyosin studies coexisted with absent rejection-related complications; in nine of 247 patients, such complications were detected (five congestive heart failure episodes due to rejection and four episodes of vascular occlusion, which resulted in five deaths), and mean HLR was 1.74 +/- 0.3 and 2.1 +/- 0.16 in the two groups, respectively (p less than 0.0001). No complications were noted in 193 studies of patients with HLR of less than 2.00, whereas in nine of 45 with HRL of 2.00 or greater, complications occurred (p less than 0.0001). None of the 23 patients prospectively followed since surgery who had a gradual decrease in MAA uptake during the first 3 months showed rejection-related complications, whereas persistent uptake was associated with complications in five of nine patients (p less than 0.001).

CONCLUSIONS
No rejection-related complications are seen coinciding with HLR of less than 2.00, whereas patients who have complications have an HLR of more than 2.00. The early 3-month pattern of decreasing MAA uptake is associated with a clinical course free of rejection-related complications, whereas a persistent pattern is a signal of the possibility of such complications.
Coronary angioplasty performed within the thrombolysis in Myocardial Infarction II study.
Authors: Baim D S , Diver D J , Feit F , Greenberg M A , Holmes D R , Weiner B H , Williams D O , Schweiger M J , Brown B G , Frederick M M 
Published: June 2012

BACKGROUND
Percutaneous transluminal coronary angioplasty (PTCA) of the infarct-related artery was performed within 42 days of recombinant tissue-type plasminogen activator (rt-PA) administration in 1,414 of the 3,534 patients who participated in the Thrombolysis In Myocardial Infarction (TIMI) II study. Primary angiographic success was obtained in 88.7%, with bypass surgery within 24 hours in 3.3% and death within 24 hours in 0.7% of patients. By 1 year, 25.1% of the 1,414 patients had sustained one or more adverse outcomes including death (3.6%), reinfarction (8.4%), or the need for further revascularization (20%).

METHODS AND RESULTS
Despite these generally favorable results, multivariate testing identified several anatomic and clinical subgroups as having an increased risk ratio (RR) for adverse outcome: Unsuccessful PTCA was more common in patients undergoing protocol-assigned PTCA within 2 hours of rt-PA administration (RR, 2.7; p less than 0.001) and in patients over age 70 years (RR, 1.7; p = 0.034). The need for further revascularization within 1 year was increased in the 30.4% of patients with multivessel disease (RR, 2.5; p less than 0.001), patients with prior angina (RR, 1.4; p less than 0.006), or those undergoing ischemia-driven PTCA within 15 hours of rt-PA administration (RR, 1.7; p = 0.022). The risk of death or recurrent infarction within 1 year was increased by the presence of multivessel disease (RR, 1.6; p = 0.007) or prior angina (RR, 1.5; p = 0.014).

CONCLUSIONS
These observations do not necessarily apply to patients undergoing primary PTCA (or PTCA after other thrombolytic agents); however, they do offer a unique yardstick against which to evaluate the results of PTCA in myocardial infarction.
Incidence and mechanism of interruption of reentrant ventricular tachycardia with rapid ventricular pacing.
Authors: Aizawa Y , Niwano S , Chinushi M , Tamura M , Kusano Y , Miyajima T , Kitazawa H , Shibata A 
Published: June 2012

BACKGROUND
Information concerning the electrophysiological characteristics of the reentrant circuit is still limited. To understand the incidence and mechanism of pacing-induced interruption of ventricular tachycardia (VT), rapid pacing was performed to entrain VT, and the local electrogram at the VT origin and the surface electrocardiogram were analyzed.

METHODS AND RESULTS
Among 25 patients, evidence of transient entrainment was confirmed in 20 patients, but the critical paced cycle length at which VT was interrupted was obtained in 13 patients when the paced cycle length was decreased in steps of 10 msec. During pacing at the critical cycle length (defined as block cycle length), changes in the local electrogram at VT origin were confirmed in all of the 13 patients; that is, 1) a change in morphology and 2) a change in the timing of activation: a sudden shortening in the stimulus to local electrogram time (third entrainment criterion by Waldo). The two changes mean that the exit is activated from a different direction (retrograde capture) because of an orthodromic block in the slow conduction zone. The QRS complex in the surface electrocardiogram showed a change in configuration from the fusion complex to the fully paced one at the same time when the exit was captured antidromically.

CONCLUSIONS
Based on our observations in these patients, ventricular tachycardia interruption is very often associated with orthodromic block in the reentrant circuit at a critical cycle length of rapid pacing.
Acute hibernation and reperfusion of the ischemic heart.
Authors: Downing S E , Chen V 
Published: June 2012

BACKGROUND
Recovery from prolonged low-flow ischemia was studied in isolated, isovolumically beating neonatal piglet hearts (n = 11) and compared with controls (n = 5).

METHODS AND RESULTS
Hearts were perfused with red blood cell-enhanced Krebs-Henseleit buffer with physiological oxygen-carrying capacity. Left ventricular mechanical function was assessed with a fluid-filled balloon. Measurements of peak systolic pressure, pressure-rate product (PRP), and +dP/dtmax were obtained at various filling pressures. Myocardial oxygen delivery and metabolism (MVO2) and lactate uptake were measured at 30-minute intervals. Control data were obtained with coronary flow (CF) set at 2 ml.min-1.g-1. CF was then reduced to 0.2 ml.min-1.g-1 for 2 hours. Thereafter, reperfusion was instituted at control levels. Hearts not subjected to ischemia were studied at identical time intervals. In these, function remained at greater than 80% after more than 3.5 hours of study. Reduction of CF to 10% was accompanied by an abrupt diminution in function (pressure-rate product) and MVO2 to 20% of control and by lactate release. These measures remained constant for the full 2 hours of ischemia. Incremental return of CF caused a lockstep increase in mechanical function and metabolism. At 30 minutes of reperfusion, PRP was 78% of time-matched controls (p = 0.05), and dP/dtmax did not differ. Increasing calcium to 5 mmol/l returned PRP (and dP/dtmax) to preischemia levels. Myocardial ATP and creatine phosphate concentrations were identical in both groups, although glycogen was lower in the ischemic hearts.

CONCLUSIONS
Acute hibernation is associated with protection of the in vitro heart from prolonged normothermic ischemia. Systolic function was only modestly lower, and velocity (dP/dtmax) did not differ from control hearts. The minimal "stunning" was fully reversible with calcium.
Mechanism of global functional recovery despite sustained postischemic regional stunning.
Authors: Lawrence W E , Maughan W L , Kass D A 
Published: June 2012

BACKGROUND
The mechanisms whereby reperfusion of a 20-minute coronary occlusion result in global functional recovery despite persistent regional dysfunction were studied in 11 open-chest reflex-blocked dogs.

METHODS AND RESULTS
Pressure-volume and pressure-thickness relations were simultaneously determined before, during, and after reperfusion of left anterior descending artery (LAD) occlusion. Wall thickness was determined by sonomicrometry in both ischemic and remote regions. Chamber systolic function was assessed by end-systolic pressure-volume relations (ESPVR) obtained by conductance catheter and defined by a slope (Ees) and volume shift at a common end-systolic pressure (delta Ves). LAD occlusion produced regional systolic thinning (-7 +/- 6%) and global left ventricular dysfunction (ESPVR shifted rightward (delta Ves = +8.6 +/- 5.1 ml, p less than 0.001) with no Ees change). After nearly 1 hour of reperfusion, LAD region thickening remained markedly reduced at 4 +/- 7% (versus 23 +/- 8%, control), yet chamber systolic function fully recovered (ESPVR shifted back leftward delta Ves = -8.9 +/- 6.5 ml). Ischemia induced a leftward shift and systolic thinning of LAD region pressure-thickness relations. Reperfusion returned end-systolic pressure-thickness relations halfway to their control position and diastolic relations fully to control position. This was primarily due to increased passive stiffening in about half the hearts and a partial return of active function in the remaining ones. The net effect was to eliminate systolic thinning over a physiological loading range, thus normalizing chamber systolic performance. Reflex activation, remote hyperfunction, or altered chamber loading did not account for the postreperfusion disparity between global and regional function.

CONCLUSIONS
These data suggest a mechanism to account for greater functional benefits of reperfusion beyond that anticipated from regional wall motion analysis.
Syncope associated with supraventricular tachycardia. An expression of tachycardia rate or vasomotor response?
Authors: Leitch J W , Klein G J , Yee R , Leather R A , Kim Y H 
Published: June 2012

BACKGROUND
Syncope in patients with supraventricular tachycardia has been suggested to be an ominous finding, predictive of rapid rates during tachycardia.

METHODS AND RESULTS
To explore the mechanism of syncope during supraventricular tachycardia, tachycardia was induced in the supine position and after passive head-up tilting to 60 degrees in 13 patients with atrioventricular (AV) node reentry, eight patients with AV reentry, and one patient with atrial tachycardia. Tilt testing was also performed in sinus rhythm for 30 minutes (the last 15 minutes with isoproterenol infusion). Mean +/- SEM age was 38 +/- 3 years, and 11 patients had a history of syncope (median number of syncopal episodes, three; range, one to 30). The cycle length of tachycardia when upright was shorter than when supine (297 +/- 9 compared with 357 +/- 10 msec, p less than 0.001), and mean blood pressure fell to a greater extent after the onset of tachycardia (fall in mean blood pressure, 53 +/- 6 compared with 24 +/- 3 mm Hg, p less than 0.001). Mean blood pressure correlated significantly with tachycardia cycle length when supine (r = 0.58, p = 0.005) but not when tilted upright (r = 0.18, p = 0.45). Syncope occurred in seven patients during upright tachycardia. These seven patients had a greater fall in mean blood pressure with upright tachycardia than the 15 patients without syncope (fall in mean blood pressure, 70 +/- 4 compared with 45 +/- 5 mm Hg, p = 0.01), but there was no difference in the tachycardia cycle length (311 +/- 10 compared with 290 +/- 11 msec, p = 0.29). Six of the seven patients with tachycardia-induced syncope also had syncope with tilt testing in sinus rhythm compared with four of the 15 patients without tachycardia-induced syncope (p = 0.02).

CONCLUSIONS
These data support the view that syncope during supraventricular tachycardia is related to vasomotor factors and does not predict a more rapid tachycardia rate.
Regional myocardial perfusion and glucose metabolism in experimental left bundle branch block.
Authors: Ono S , Nohara R , Kambara H , Okuda K , Kawai C 
Published: June 2012

BACKGROUND
Several authors have reported cases in which 201Tl scintigraphy demonstrated perfusion abnormality in the septum of patients with left bundle branch block (LBBB) and normal coronary arteriogram. The mechanism of this abnormality, however, remains to be clarified.

METHODS AND RESULTS
To determine whether LBBB itself induces abnormal myocardial perfusion and ischemia and to elucidate its mechanism, we used an in vivo animal model. LBBB was induced by right ventricular pacing in 17 open-chest dogs. We examined myocardial perfusion and glucose uptake using 201Tl and 18F-labeled 2-fluoro-2-deoxy-D-glucose. 201Tl activity in the septum was reduced to 74.7 +/- 14.5% of its maximal activity, and mean activity was 86.5 +/- 5.3% in the free wall (p less than 0.05). 18F activity in the septum was also reduced compared with that in the free wall (67.4 +/- 12.1% versus 88.0 +/- 5.2%, p less than 0.05). Regional myocardial blood flow was significantly reduced in the septum compared with the free wall, averaging 0.53 +/- 0.18 ml/min/g versus 0.84 +/- 0.14 ml/min/g, respectively (p less than 0.01). Systolic thickening in the septum was reduced from 1.36 +/- 0.20 to 0.98 +/- 0.04 (p less than 0.01) after the induction of LBBB, and the intramyocardial pressure in the septum in diastolic phase, in which the major flow of left anterior descending coronary artery (LAD) exists, increased from 26.6 +/- 10.5 to 57.8 +/- 22.2 mm Hg (p less than 0.02). Mean aortic pressure, LAD flow, and lactate extraction rate showed no significant change.

CONCLUSIONS
LBBB itself may reduce myocardial perfusion and glucose uptake in the septum because of impaired systolic thickening and augmented intramyocardial pressure in the septum; however, this is not necessarily related to septal ischemia.
Factors related to end-systolic volume are important determinants of peak early diastolic transmitral flow velocity.
Authors: Courtois M , Mechem C J , Barzilai B , Ludbrook P A 
Published: June 2012

BACKGROUND
Three important determinants of left ventricular (LV) peak early diastolic filling rate, which is related directly to the magnitude of the transmitral pressure difference, are the rate of LV isovolumic pressure fall (T1/2), left atrial (LA) pressure at mitral valve opening (X1), and end-systolic volume (ESV).

METHODS AND RESULTS
To delineate the relative degrees to which these factors contribute to the magnitude of peak early diastolic filling rate, we measured LA and regional intra-LV pressures with micromanometers, LV volume with contrast angiography, and peak transmitral flow velocity (E) with transesophageal Doppler echocardiography in 16 anesthetized closed-chest dogs. E did not correlate significantly with either X1 (r = -0.255) or T1/2 (r = -0.281). Multivariate analysis, with E entered as the dependent variable and X1 and T1/2 as independent variables, also failed to reach significance (R = 0.310). E correlated significantly with ESV (r = -0.633, p less than 0.009). Using multivariate analysis, the major determinants of ESV were found to be LV contractility (+dP/dt), afterload (aortic diastolic pressure, AOdias), and preload (end-diastolic volume, EDV) (R = 0.848, p less than 0.001). E correlated significantly with two of the determinants of ESV (+dP/dt and AOdias) (R = 0.906, p less than 0.001); however, the addition of EDV did not significantly improve the multivariate relation (R = 0.911). To determine whether X1 or T1/2 would add significantly to the above multivariate relation, these factors were entered individually along with +dP/dt and AOdias as third independent variables. Neither the addition of X1 (R = 0.906) or T1/2 (R = 0.926) resulted in a significant improvement in the prediction of E.

CONCLUSIONS
Our observations confirm the importance of factors related to ESV as important determinants of early diastolic filling. These relations suggest that the process of early diastolic function is intimately related to systolic function.