bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-dimensional echocardiography. In vivo validation for right ventricular volume and function.
Authors: Jiang L , Siu S C , Handschumacher M D , Luis Guererro J , Vazquez de Prada J A , King M E , Picard M H , Weyman A E , Levine R A 
Published: June 2012

BACKGROUND
Current two-dimensional echocardiographic measures of right ventricular volume are limited by the asymmetrical and crescentic shape of the ventricle and by difficulty in obtaining standardized views. Three-dimensional echocardiographic reconstruction, which does not require geometric assumptions or standardized views, may therefore have potential advantages for determining right ventricular volume. Three-dimensional techniques, however, have not been applied to the right ventricle in vivo, where cardiac motion and contraction could affect accuracy. The purpose of this study was to determine the feasibility and accuracy of three-dimensional echocardiographic reconstruction for quantifying right ventricular volume and function in vivo. In particular, it was designed to test the accuracy of a newly developed system that provides rapid, efficient, and automated three-dimensional data collection (minimizing motion effects) and takes advantage of the full three-dimensional data set to obtain volume.

METHODS AND RESULTS
The three-dimensional system was applied to reconstruct the right ventricle and measure its volume and function during 20 hemodynamic stages created in five dogs. Actual instantaneous volumes were measured continuously by an intracavitary balloon connected to an external column. Hemodynamics were varied by volume loading and induction of ischemia. Three-dimensional reconstruction successfully reproduced right ventricular volume compared with actual values at end diastole (y = 1.0 chi-3.4, r = .99, SEE = 1.8 mL) and end systole (y = 1.0 chi+ 2.0, 4 = .98, SEE = 2.5 mL). The mean difference between calculated and actual volumes throughout the cycle was 2.1 mL, or 4.9% of the mean. Ejection fraction also correlated well with actual values (y = 0.96 chi-0.3, r = .98, SEE = 3.3%).

CONCLUSIONS
Despite the irregular crescentic shape of the right ventricle, this newly developed three-dimensional system and surfacing algorithm can accurately reconstruct its shape and quantitate its volume and function in vivo without geometric assumptions. The increased efficiency of the system should increase applicability to issues of clinical and research interest.
Exclusion of atrial thrombus by transesophageal echocardiography does not preclude embolism after cardioversion of atrial fibrillation. A multicenter study.
Authors: Black I W , Fatkin D , Sagar K B , Khandheria B K , Leung D Y , Galloway J M , Feneley M P , Walsh W F , Grimm R A , Stollberger C 
Published: June 2012

BACKGROUND
Transesophageal echocardiography (TEE) has been used recently to detect atrial thrombi before cardioversion of atrial arrhythmias. It has been assumed that embolic events after cardioversion result from embolism of preexisting atrial thrombi that are accurately detected by TEE. This study examined the clinical and echocardiographic findings in patients with embolism after cardioversion of atrial fibrillation despite exclusion of atrial thrombi by TEE.

METHODS AND RESULTS
Clinical and echocardiographic data in 17 patients with embolic events after TEE-guided electrical (n = 16) or pharmacological (n = 1) cardioversion were analyzed. All 17 patients had nonvalvular atrial fibrillation, including four patients with lone atrial fibrillation. TEE before cardioversion showed left atrial spontaneous echo contrast in five patients and did not show atrial thrombus in any patient. Cardioversion resulted in return to sinus rhythm without immediate complication in all patients. Thirteen patients had cerebral embolic events and four patients had peripheral embolism occurring 2 hours to 7 days after cardioversion. None of the patients were therapeutically anticoagulated at the time of embolism. New or increased left atrial spontaneous echo contrast was detected in four of the five patients undergoing repeat TEE after cardioversion including one patient with a new left atrial appendage thrombus.

CONCLUSIONS
Embolism may occur after cardioversion of atrial fibrillation in inadequately anticoagulated patients despite apparent exclusion of preexisting atrial thrombus by TEE. These findings suggest de novo atrial thrombosis after cardioversion or imperfect sensitivity of TEE for atrial thrombi and suggest that screening by TEE does not obviate the requirement for anticoagulant therapy at the time of and after cardioversion. A randomized clinical trial is needed to compare conventional anticoagulant management with a TEE-guided strategy including anticoagulation after cardioversion.
Coronary atherosclerotic wall thickening and vascular reactivity in humans. Elevated high-density lipoprotein levels ameliorate abnormal vasoconstriction in early atherosclerosis.
Authors: Zeiher A M , Schächlinger V , Hohnloser S H , Saurbier B , Just H 
Published: June 2012

BACKGROUND
Abnormal vascular reactivity represents a fundamental disturbance in vascular biology with the development of atherosclerosis. Because endothelial vasodilator function plays a pivotal role in controlling vasomotor tone, we hypothesized that atherosclerotic wall thickening might directly interfere with deficient endothelium-mediated dilation and thereby contribute to the abnormal reactivity of atherosclerotic arteries in vivo.

METHODS AND RESULTS
In 26 patients without focal stenoses in the left anterior descending coronary artery, acetylcholine (0.036 to 3.6 micrograms/mL) was infused into the artery to evaluate endothelium-mediated vasodilation. Segmental vasomotor responses to acetylcholine were correlated with the local extent of atherosclerotic wall thickening quantitated by intracoronary ultrasound examination. Seventeen of the patients also underwent cold pressor testing to assess the vasoreactivity to sympathetic activation. The response of coronary artery segments to acetylcholine varied from 35% dilation to 52% constriction and demonstrated a segmental pattern, with dilation and constriction observed in different segments of the same artery. The vasomotor response to acetylcholine was closely correlated with the extent of local atherosclerotic wall thickening (r = -.82, P < .0001). Over the entire range of atherosclerotic wall thickening, segments from patients with elevated high-density lipoprotein (HDL) cholesterol serum levels (> 75th percentile) demonstrated a significantly blunted constrictor response to acetylcholine (P < .01 at the maximal acetylcholine concentration) compared with segments from patients with HDL cholesterol < 75th percentile. The degree of constriction or dilation in response to the acetylcholine infusion correlated with the response to cold pressor testing (r = .75, P < .0001). Again, the cold pressor test-induced constrictor response was significantly (P < .05) blunted in segments from patients with elevated HDL cholesterol serum levels compared with those from patients with HDL cholesterol < 75th percentile despite equal degrees of atherosclerotic wall thickening.

CONCLUSIONS
Coronary vasomotor responses to the endothelium-dependent dilator acetylcholine and to sympathetic stimulation by cold pressor test correlate with local atherosclerotic wall thickening. Thus, the degree of abnormal local vascular reactivity is closely related to the extent of atherosclerotic "plaque load" in human epicardial arteries in vivo. Elevated HDL cholesterol serum levels ameliorate abnormal vasoconstriction at any given extent of atherosclerotic wall thickening, suggesting that HDL cholesterol exerts a beneficial effect on abnormal vascular reactivity, a fundamental functional disturbance associated with coronary atherosclerosis.
High-density lipoprotein cholesterol and premature coronary heart disease in urban Japanese men.
Authors: Kitamura A , Iso H , Naito Y , Iida M , Konishi M , Folsom A R , Sato S , Kiyama M , Nakamura M , Sankai T 
Published: June 2012

BACKGROUND
The objective of this study was to examine the relation of high-density lipoprotein cholesterol (HDL-C) to coronary heart disease in Japanese men whose serum total cholesterol is low by Western standards.

METHODS AND RESULTS
A prospective, observational study based on 7.7 years of follow-up for incidence of coronary heart disease and stroke was conducted. The subjects were 6408 middle-aged male workers aged 40 to 59 years at baseline in urban companies in Osaka, Japan, whose mean serum total cholesterol was 5.10 mmol/L. Mean HDL-C adjusted for age, total cholesterol, systolic blood pressure, alcohol intake, cigarette smoking, and body mass index was 1.27 to 1.28 mmol/L for men who developed coronary heart disease (n = 46) or definite myocardial infarction (n = 21) compared with 1.46 mmol/L for those free of cardiovascular disease (n = 6256; difference, P < .01). There was no significant difference in mean HDL-C between stroke cases (n = 33) and those free of cardiovascular disease. The incidence rates of coronary heart disease and definite myocardial infarction, adjusted for the other risk factors, were three to four times higher in the lowest HDL-C quartile (< 1.24 mmol/L) than the highest quartile (> or = 1.66 mmol/L), and there was a significant dose response for definite myocardial infarction. Serum total cholesterol was positively and significantly associated with coronary heart disease incidence. Furthermore, the inverse association for HDL-C was apparent among men with total cholesterol < 5.69 mmol/L (mean total cholesterol, 4.76 mmol/L) and men with total cholesterol > or = 5.69 mmol/L (mean total cholesterol, 6.26 mmol/L).

CONCLUSIONS
Coronary heart disease incidence is inversely related to HDL-C in urban Japanese middle-aged men, whose mean total cholesterol (5.10 mmol/L) is relatively low.
Potentiation of isosorbide dinitrate effects with N-acetylcysteine in patients with chronic heart failure.
Authors: Mehra A , Shotan A , Ostrzega E , Hsueh W , Vasquez-Johnson J , Elkayam U 
Published: June 2012

BACKGROUND
Supply of sulfhydryl groups with the administration of N-acetylcysteine (NAC) has been reported to reverse tolerance to nitroglycerin but not to isosorbide dinitrate (ISDN). Lack of interaction between NAC and ISDN was suggested as an explanation for these findings. The present study was therefore designed to further evaluate this hypothesis. For this purpose, we compared the hemodynamic and hormonal effects of ISDN when given alone and in combination with NAC.

METHODS AND RESULTS
We performed a randomized, cross-over design evaluation of the hemodynamic and hormonal effects of ISDN and ISDN + NAC in 14 patients with chronic congestive heart failure due to left ventricular systolic dysfunction. The findings of this study demonstrated a substantial NAC-mediated potentiation of ISDN effect on mean right atrial pressure (-11 +/- 21% versus -38 +/- 27%, -17 +/- 20% versus -34 +/- 27%, and -7 +/- 20% versus -25 +/- 26% at 2, 3, and 4 hours, respectively; all P < .05), mean pulmonary artery wedge pressure (-18 +/- 16% versus -33 +/- 14%, -15 +/- 25% versus -33 +/- 19%, -14 +/- 22% versus -25 +/- 22%, and -16 +/- 16% versus -26 +/- 16% at 2, 3, 4, and 5 hours, respectively; all P < .05), mean pulmonary artery pressure (-8 +/- 11% versus -20 +/- 15% at 3 hours, P < .05), and cardiac output (an increase of 2 +/- 16% versus 25 +/- 20% at 4 hours, P < .05). Although there were no significant changes in serum catecholamine levels and plasma renin concentration with both regimens, ISDN + NAC resulted in a greater fall in plasma levels of atrial natriuretic peptide (296 +/- 251 pg/mL after ISDN versus 202 +/- 118 pg/mL after ISDN + NAC, P < .05).

CONCLUSIONS
The results of this study provide strong evidence for the existence of an interaction between thiols and ISDN and further support the role of sulfhydryl groups in the activation and therapeutic action of organic nitrates. The discrepancy between the results of this study demonstrating NAC-induced potentiation of ISDN effects and a previous study showing failure to reverse ISDN tolerance with NAC may suggest that ISDN-NAC interaction requires normal intracellular levels of sulfhydryl groups and does not occur after intracellular sulfhydryl group depletion.
Body fat and sympathetic nerve activity in healthy subjects.
Authors: Scherrer U , Randin D , Tappy L , Vollenweider P , Jéquier E , Nicod P 
Published: June 2012

BACKGROUND
Obesity is associated with an increased incidence of cardiovascular complications, but the underlying mechanism is unknown. In experimental animals, overfeeding is associated with sympathetic activation, and there is evidence that adrenergic mechanisms contribute to cardiovascular complications.

METHODS AND RESULTS
We recorded resting postganglionic sympathetic nerve discharge (using intraneural microelectrodes) to skeletal muscle blood vessels in 37 healthy subjects covering a broad spectrum of percent body fat. To assess potential functional consequences of sympathetic nerve discharge, we simultaneously measured calf vascular resistance and energy expenditure. The resting rate of sympathetic nerve discharge to skeletal muscle was directly correlated with body mass index (r = .67, P < .0001) and percent body fat (r = .64, P < .0001). In addition to body fat, muscle sympathetic nerve activity was correlated with age (r = .40, P < .02), plasma insulin concentration (r = .34, P < .04), and plasma lactate concentration (r = .35, P < .04). Together, these four covariates accounted for 58% of the variance of muscle sympathetic nerve activity (P < .0001). The rate of sympathetic nerve discharge to calf blood vessels was directly correlated with calf vascular resistance (r = .40, P < .02) but did not predict energy expenditure (r = .22, P = .19).

CONCLUSIONS
In healthy humans, body fat is a major determinant of the resting rate of muscle sympathetic nerve discharge. Overweight-associated sympathetic activation could represent one potential mechanism contributing to the increased incidence of cardiovascular complications in overweight subjects.
Efficacy of a single-lead unipolar transvenous defibrillator compared with a system employing an additional coronary sinus electrode. A prospective, randomized study.
Authors: Kudenchuk P J , Bardy G H , Dolack G L , Poole J E , Mehra R , Johnson G 
Published: June 2012

BACKGROUND
Recent development of a prototype single-lead unipolar transvenous defibrillator offers the possibility of device implantation with the ease of a permanent pacemaker. Lowering defibrillation energy requirements would allow for a further reduction in defibrillator generator size and enhance the feasibility of pacemaker-like placement. However, if achieving a lower defibrillation energy requires placing additional intracardiac leads, the potential advantage of a smaller generator may be offset by the disadvantages of a more complex lead system. The purpose of this study was to compare defibrillation energy requirements of a single-lead unipolar defibrillator with a three-electrode system employing an additional lead in the coronary sinus.

METHODS AND RESULTS
Testing of a single-lead unipolar biphasic pulse defibrillation system versus a three-electrode system with an additional coronary sinus lead was performed in prospective, randomized fashion in 15 patients with a history of ventricular tachycardia or fibrillation. Ventricular fibrillation was induced with alternating current, and defibrillation threshold was measured by a pulse given 10 seconds after arrhythmia induction. The mean defibrillation threshold stored energy and mean leading edge voltage did not significantly differ between the two systems (11.3 +/- 5.9 J versus 9.9 +/- 5.2 J and 418 +/- 118 V versus 390 +/- 112 V, respectively; P > .4). Using either defibrillation system, all patients were successfully defibrillated by < 24 J and over half of patients by < 10 J.

CONCLUSIONS
A unipolar transvenous biphasic defibrillation system is an effective means of treating ventricular fibrillation. The added complexity of additional leads is not offset by any significant improvement in defibrillation efficacy or energy requirements. Given the simplicity and effectiveness of a single-lead system coupled with a small generator, placement of defibrillation systems may now approach the ease of pacemaker implantation.
Reduction of radiation exposure while maintaining high-quality fluoroscopic images during interventional cardiology using novel x-ray tube technology with extra beam filtering.
Authors: den Boer A , de Feyter P J , Hummel W A , Keane D , Roelandt J R 
Published: June 2012

BACKGROUND
Radiographic technology plays an integral role in interventional cardiology. The number of interventions continues to increase, and the associated radiation exposure to patients and personnel is of major concern. This study was undertaken to determine whether a newly developed x-ray tube deploying grid-switched pulsed fluoroscopy and extra beam filtering can achieve a reduction in radiation exposure while maintaining fluoroscopic images of high quality.

METHODS AND RESULTS
Three fluoroscopic techniques were compared: continuous fluoroscopy, pulsed fluoroscopy, and a newly developed high-output pulsed fluoroscopy with extra filtering. To ascertain differences in the quality of images and to determine differences in patient entrance and investigator radiation exposure, the radiated volume curve was measured to determine the required high voltage levels (kVpeak) for different object sizes for each fluoroscopic mode. The fluoroscopic data of 124 patient procedures were combined. The data were analyzed for radiographic projections, image intensifier field size, and x-ray tube kilovoltage levels (kVpeak). On the basis of this analysis, a reference procedure was constructed. The reference procedure was tested on a phantom or dummy patient by all three fluoroscopic modes. The phantom was so designed that the kilovoltage requirements for each projection were comparable to those needed for the average patient. Radiation exposure of the operator and patient was measured during each mode. The patient entrance dose was measured in air, and the operator dose was measured by 18 dosimeters on a dummy operator. Pulsed compared with continuous fluoroscopy could be performed with improved image quality at lower kilovoltages. The patient entrance dose was reduced by 21% and the operator dose by 54%. High-output pulsed fluoroscopy with extra beam filtering compared with continuous fluoroscopy improved the image quality, lowered the kilovoltage requirements, and reduced the patient entrance dose by 55% and the operator dose by 69%.

CONCLUSIONS
High-output pulsed fluoroscopy with a grid-switched tube and extra filtering improves the image quality and significantly reduces both the operator dose and patient dose.
Pulmonary hypertension in patients with human immunodeficiency virus infection. Comparison with primary pulmonary hypertension.
Authors: Petitpretz P , Brenot F , Azarian R , Parent F , Rain B , Herve P , Simonneau G 
Published: June 2012

BACKGROUND
Previously reported cases of patients with pulmonary hypertension (PH) and human immunodeficiency virus (HIV) infection are poorly documented regarding baseline hemodynamics and potential for pulmonary vasodilatation. The purpose of this report was to compare HIV-infected patients who had PH with non-HIV-infected patients who had primary pulmonary hypertension (PPH) in terms of (1) clinical characteristics, (2) hemodynamics in baseline conditions and during a short-term vasodilator trial with epoprostenol, and (3) survival.

METHODS AND RESULTS
Between April 1987 and August 1992, 20 HIV-infected patients with PH and 93 non-HIV-infected patients with PPH were referred to our department. At the time of referral, baseline right-side heart hemodynamics were obtained in addition to demographic variables and medical history. A short-term vasodilator trial with epoprostenol was performed in 19 of 20 HIV-infected and 86 of 93 non-HIV-infected patients. Outcome and survival were analyzed and compared for both groups (22 transplant recipients were excluded from the group of patients with PPH). At the time of diagnosis of PH, HIV-infected patients significantly differed from non-HIV-infected patients in age (32 +/- 5 versus 42 +/- 13 years; P < .05) and degree of disability (New York Heart Association functional class III or IV, 50% versus 75%; P < .01). The proportion of disease states known to be associated with PPH (Raynaud's phenomenon, migraine, collagen disease without overt symptoms and signs, or a positive family history of PPH) was similar in the two groups. HIV-infected patients had a severe but significantly lower level of PH than patients with PPH. The percentage of responders to epoprostenol and the level achieved in pulmonary vasodilatation were similar in the two groups. PH was the cause of death in 8 of the 10 HIV-infected patients who died within 1 year after the diagnosis of PH. Overall survival was poor and not significantly different between the two groups. Pathological findings in lung tissue obtained from 3 HIV-infected patients were close to those seen in most of the lung specimens available from 27 patients with PPH and resembled plexogenic pulmonary arteriopathy.

CONCLUSIONS
These results support the view that HIV infection may now be regarded as another common disease state that can be associated with PPH development. The lower initial severity in HIV-infected patients may be due to the close medical attention usually devoted to such patients, who may account for an earlier diagnosis. However, the overall survival rate of HIV-infected patients with PH appeared to be as poor as in non-HIV-infected patients with PPH.