tbuckley/cabot-search huggingface dataset:
The cellular electrophysiologic effects of digitalis on human atrial fibers.
Authors: A JHordof, ASpotnitz, LMary-Rabine, R NEdie, M RRosen
Journal: Circulation (1978)

We used microelectrode techniques to study the indirect and direct actions of ouabain on human atrial fibers (HAF) obtained from patients with congenital heart disease undergoing open heart surgery. At 15 min of superfusion ouabain, 2 X 10(-7) M, induced an increase in maximum diastolic potential (MDP), action potential (AP) amplitude and upstroke velocity of phase 0 depolarization (Vmax) and a decrease in AP duration. Spontaneously beating HAF showed a decrease in automaticity. Acetylcholine (3 X 10(-6) M) induced identical effects on AP characteristics and automaticity. Prior treatment with atropine (1 X 10 (-6) M) blocked these effects of ouabain and acetylcholine. Superfusion with ouabain (2 X 10 (-7) M) for 30 to 90 min resulted in decreased MDP, AP amplitude and Vmax, and a further decrease in AP duration. Phase 4 depolarization and spontaneous rate increased and delayed afterdepolarization and tachyarrythmia occurred. The ACh-like effects of digitalis decrease automaticity and increase MDP of HAF; ...
Tetralogy of Fallot: postoperative electrophysiologic studies.
Authors: W HNeches, S CPark, R AMathews, C CLenox, JMarin-Garcia, J RZuberbuhler
Journal: Circulation (1977)

Electrophysiologic studies performed during postoperative cardiac catheterization in 51 patients following repair of tetralogy of Fallot (TF) were compared with studies performed in a control group of 30 patients. These studies include His bundle electrograms, measurement of atrioventricular (A-V) conduction at progressively increasing atrial pacing rates, and evaluation of sinus node recovery time. More postoperative TF patients (20%) had prolonged H-V intervals compared to the controls (7%). With atrial pacing, no patient in the control group developed second degree A-V block below 160 beats/min, while 23% of the postoperative TF patients developed block below this level. Half of these patients had normal His bundle studies. Stress of the A-V conduction system by atrial pacing may unmask conduction abnormalities not present on the surface electrocardiogram or on His bundle electrogram. Two-thirds of the patients had some form of conduction abnormality on the basis of evaluation of one or more parameters...
Is coronary flow reserve in response to papaverine really normal in syndrome X
Authors: AChauhan, P AMullins, M CPetch, P MSchofield
Journal: Circulation (1994)

BACKGROUNDAn impaired coronary flow reserve in syndrome X has been demonstrated by many studies. Recently, however, a normal coronary flow reserve in response to papaverine was reported, but the number of patients in these studies was small. The aim of this study was to investigate whether coronary flow reserve in response to intracoronary papaverine is really impaired in syndrome X.METHODS AND RESULTSWe investigated 53 syndrome X patients (typical angina, a positive exercise test, and completely normal coronary arteries on angiography) and 26 heart transplant patients with normal coronary arteries (control group). All antianginal medications were stopped 48 hours before the study. A 3.6F intracoronary Doppler catheter was positioned in the proximal left anterior descending coronary artery and was connected to a Millar velocimeter. The coronary blood flow velocity at rest and in response to a hyperemic dose of papaverine was measured. Coronary flow reserve was defined as the ratio of hyperemic coronary bl...
Changes in intracellular free calcium concentration during long exposures to simulated ischemia in isolated mammalian ventricular muscle.
Authors: J ALee, D GAllen
Journal: Circulation Research (1992)

Intracellular free calcium concentration ([Ca2+]i) was measured in isolated ferret ventricular papillary muscles during and after long exposures to ischemia. All experiments were performed at 37 degrees C, and the muscles were stimulated at 1 Hz. Ischemia was simulated by changing from superfusion with oxygenated Tyrode's solution to superfusion with water-saturated gas (95% N2-5% CO2), thus simultaneously stopping oxygenation and restricting the extracellular space. [Ca2+]i was measured with aequorin, which was microinjected into superficial cells of the preparation. Exposure to ischemia caused a complex series of changes in [Ca2+]i. In the first few minutes the changes in [Ca2+]i were variable; however, after approximately 5 minutes all preparations exhibited a progressive increase in amplitude and duration of the stimulated rise in [Ca2+]i (the calcium transient). The amplitude of the calcium transients peaked after approximately 18 minutes of ischemia, when they were 339% of the control value. After t...
Abstract 15975: Association of Maximum Troponin Levels With Myocardial Infarction Diagnosis and Higher Mortality
Authors: Jerry Fan, Kendall Hammonds, Bright Izekor, Clinton Jones, Patrick McGrade, Jeffrey B Michel, Robert J Widmer
Journal: Circulation (2020)

Introduction: Cardiac troponin I (TnI) is a sensitive and specific marker of acute myocardial infarction (AMI). However, a wide range of non-AMI conditions can also cause significant elevations in cardiac troponins. Given the deleterious impact of misdiagnosis, the ability to risk stratify patients who present with an elevated troponin is paramount. Hypothesis: We hypothesized that maximum TnI would be more predictive of mortality and the diagnosis of AMI than the initial or change in TnI. Methods: Records of 30,173 patients from a nine-hospital system in Texas were reviewed over a 24-month period 2016-2018. Data were collected on patients &gt; 40 years of age and included international classification of disease (ICD-10) diagnoses, TnI, demographic data (age, sex, race, smoking status, chronic medical conditions), death during hospitalization, and readmission within 30 days. Results: Notable finding include TnI as a significant predictor of death with odds of death increased by 0.9% (1.009, 95% CI 1.004-1.013) for initial, and 0.7% (1.007, 95% CI 1.005-1.009) for delta and maximum TnI. An ROC curve demonstrated a statistically significant predictive ability of death for the maximum TnI level (0.6782, 95% CI (0.6576, 0.6989)) when compared to the initial and change in TnI. We analyzed the initial TnI as a significant predictor of AMI demonstrating the odds of AMI increased by 7.4% as initial TnI values increased (1.074, 95% CI 1.063-1.085), and 3.1% for delta and maximum TnI (1.031, 95% CI 1.028-1.034). A separate ROC curve demonstrated that the maximum TnI level 0.9401, 95% CI (0.9353, 0.9449) showed a statistically significant predictive ability to predict an AMI compared to initial change in TnI. Conclusions: Regardless of TnI level, a detectable TnI results in an increased risk of in-hospital mortality. Our study demonstrates that the maximum TnI level is a more sensitive and specific predictor of mortality when compared to delta or initial TnI. Similarly, the maximum TnI is the most predictive of an AMI versus other causes of TnI elevation. Further studies are needed to correlate TnI levels and clinical manifestations, which may be helpful in redefining AMI to better distinguish AMI from non-AMI diagnoses.
Natural history of contractile abnormalities after acute myocardial infarction in man: severity and response to nitroglycerin as a function of time.
Authors: KRamanathan, M MBodenheimer, V SBanka, R HHelfant
Journal: Circulation (1981)

The natural history of contraction abnormalities and their response after acute myocardial infarction in man were studied using radionuclide angiography. Sixteen patients were studied before and after sublingual nitroglycerin within 24 hours, 5-7 days and 4-6 weeks after the onset of chest pain. Within 24 hours, central chord shortening in the zone of infarction was reduced to 13.1 +/- 9.8%, but improved 27.2 +/- 18.4% (p less than 0.001) after nitroglycerin. After 5-7 days, central chord shortening improved similarly, but less markedly, from 12.9 +/- 9.2% to 24.4 +/- 13.2% (p less than 0.001). After nitroglycerin 4--6 weeks after the acute myocardial infarction, the central chord showed no response to nitroglycerin; it was 13.9 +/- 10.9% before and 13.4 +/- 2.5% after nitroglycerin. Changes in the lateral chords paralleled changes in the central chords in the three studies. Nonischemic zone improvement after nitroglycerin in all three studies. Global ejection fraction improved and end-diastolic and end-s...
Diffuse 18F-FDG PET/CT Uptake of the Bilateral Atrial Walls in Atrioventricular Nodal Re-entrant Tachycardia
Authors: Yacine El Yaagoubi, Caroline Prunier-Aesch, Alain Chetanneau, Eric Delannoy, Clémence Antoine
Journal: Clinical Nuclear Medicine (2021)

Abstract An 84-year-old man was referred for the evaluation of a suspected gastrointestinal neoplasia. 18 F-FDG PET/CT scan was performed showing, in addition to the physiological myocardial FDG uptake in the left ventricular wall, an unusual diffuse FDG uptake of the bilateral atrial walls. During his visit to the nuclear medicine unit, the patient became unwell, and an ECG was performed, suggestive of an atrioventricular nodal re-entrant tachycardia. Our case highlights the importance of including supraventricular arrhythmia such as atrioventricular nodal re-entrant tachycardia in the differential diagnosis of atrial FDG uptake.
Disseminated Talaromyces infection in an AIDS patient
Authors: Gregorio Basile, Matteo Piccica, Iacopo Vellere, Massimo Meli, Marcello Mazzetti, Daniela Massi, Vincenza Maio, Daniela Cecconi, Gian Maria Rossolini, Alessandro Bartoloni, Lorenzo Zammarchi
Journal: Clinical Microbiology and Infection (2021)
Effects of methylprednisolone on the ischemic damage in patients with acute myocardial infarction.
Authors: J EMadias, W BHood
Journal: Circulation (1982)

In this double-blind randomized study, 19 patients with acute transmural myocardial infarction were treated with methylprednisolone administered 4.4 +/- 0.7 hours (+/- SEM) after the onset of chest pain, and were compared with 21 patients who received placebo 4.5 +/- 0.4 hours after the start of clinical symptoms. The two groups were comparable in reference to sex, prevalence of risk factors, clinical status on admission, location of myocardial infarction and magnitude of ischemic injury as assessed by standard ECGs and precordial ST-segment and QRS maps. The treated patients, however, were older than the patients who received placebo. Methylprednisolone in an i.v. dose of 2.0 g was administered on admission and a similar dose was infused 3 hours later. Placebo administration followed an identical schedule. Mortality, cardiac rupture, incidence of ventricular arrhythmias, blocks, extension of myocardial infarction, pericarditis, postinfarction chest pain, persistent ST-segment elevation at discharge, and ...
Myocardial beta-adrenergic receptor expression and signal transduction after chronic volume-overload hypertrophy and circulatory congestion.
Authors: H KHammond, D ARoth, P AInsel, C EFord, F CWhite, A SMaisel, M GZiegler, C MBloor
Journal: Circulation (1992)

BACKGROUNDThe volume-overload, high-output state induced by aortocaval fistula is unique because it is not generally associated with marked abnormalities of contractile function. Thus, changes in beta-adrenergic receptor (beta AR) expression should reflect more directly the influence of neurohumoral adrenergic tone, clarifying the manner in which peripheral (neurohumoral) versus primary myocardial factors are operative in decreased beta AR-dependent signal transduction.METHODS AND RESULTSWe examined the beta-adrenergic receptor-responsive adenylyl cyclase pathway in hearts from pigs subjected to volume-overload hypertrophy with circulatory congestion. Nine pigs underwent initial pharmacological and hemodynamic studies, and, 5 weeks after aortocaval fistula placement, when signs of circulatory congestion were evident, these measurements were repeated. Biochemical analyses of plasma and myocardium from these animals and seven normal animals were compared. Experimental animals showed signs of circulatory con...
Right ventricular infarction: role of the moderator band artery in determining infarct size.
Authors: H MHaupt, G MHutchins, G WMoore
Journal: Circulation (1983)

We studied 19 patients with proximal right coronary artery occlusions associated with acute myocardial infarcts less than 30 days old. Right ventricular infarct size, determined as a percentage of right ventricular surface area, ranged from 0% to 29%. Correlation of 24 variables measuring infarct size, chamber size and coronary artery disease failed to demonstrate a significant correlation with the extent of right ventricular infarction. However, estimates of the degree of obstruction to potential collateral flow into the right coronary arterial system from the left anterior descending coronary artery, especially through the moderator band artery, showed a significant positive correlation with infarct size (p less than 0.02). Among the five patients with massive (greater than 25%) right ventricular infarction, four had significant (greater than 75%) obstruction of the left anterior descending system, resulting in potentially impaired collateral blood flow; the other patient had normal coronary arteries an...
Spatial Inequities in COVID-19 Testing, Positivity, Confirmed Cases, and Mortality in 3 U.S. Cities
Authors: Usama Bilal, Loni P. Tabb, Sharrelle Barber, Ana V. Diez Roux
Journal: Annals of Internal Medicine (2021)

Preliminary evidence has shown inequities in coronavirus disease 2019 (COVID-19)-related cases and deaths in the United States.
Alternans of the ST segment in Prinzmetal's angina.
Authors: M JKleinfeld, J JRozanski
Journal: Circulation (1977)

Alternans of the elevated ST segment (STEA) was found in 8 of 21 patients (38%) with Prinzmetal's variant angina. In addition to STEA, all eight patients had varying cardiac arrhythmias: multiple premature ventricular depolarizations in eight, ventricular tachycardia in five, and ventricular fibrillation in three. There was no consistent temporal relationship between the occurrence of STEA and the cardiac arrhythmias. Alternans occurred during periods when no arrhythmias were present. All eight patients underwent coronary angiography. Spontaneous coronary artery spasm was documented angiographically in three patients including two who had minimal or no coronary atherosclerotic disease. Six patients had severe, fixed, occlusive coronary artery disease. Possible mechanisms for STEA include: 1) failure of regions of myocardium to depolarize on alternate beats due to variation in conduction and refractoriness between ischemic and nonischemic zones of myocardium, and 2) electrical alternans of the transmembran...
A Noninvasive Panel for Diagnosis of Esophageal Varices in Patients With Compensated Cirrhosis
Authors: E-S Tharwa, M Abdel-Samiee, K Gamil, O El-Abd, E Abd-Almonem
Journal: Endoscopy (2021)

Aims Varices are present in 30-40 % of patients with compensated cirrhosis (Child–Pugh class A). Although screening endoscopy for esophageal varices (O.V.) is recommended to all patients with cirrhosis, this recommendation is not a result of evidence– based data. We studied the association of (platelet count/spleen diameter ratio, insulin resistance and splenoportal index) and the presence of O.V. in patients with compensated cirrhosis.
Identification of ventricular tachycardia with use of the morphology of the endocardial electrogram.
Authors: J JLangberg, W JGibb, D MAuslander, J CGriffin
Journal: Circulation (1988)

Currently available antitachycardia devices rely primarily on timing information to define abnormal rhythms. It would be useful to have more specific means of automatically identifying pathologic tachycardias. Using unfiltered (0.04 to 500 Hz bandpass) recordings made during electrophysiologic testing in 10 patients with ventricular tachycardia (VT), we studied the differences in electrogram morphology during sinus rhythm and VT. Signals were digitized at 1 kHz. A template of a normal sinus rhythm electrogram was created for each patient by averaging five sinus complexes from the beginning of each study. Ten sinus electrograms just before the onset of VT and 10 electrograms during stable monomorphic VT were compared with this template. The  in morphology between a given electrogram and its template was quantitated by superimposing the two signals and measuring the  between the curves. There was no overlap in the ranges of these area of the difference measurements between sinus and VT elect...
Isolation of gene markers of differentiated and proliferating vascular smooth muscle cells.
Authors: C MShanahan, P LWeissberg, J CMetcalfe
Journal: Circulation Research (1993)

To isolate specific markers of both differentiated and proliferating vascular smooth muscle cells (VSMCs), we used the technique of differential cDNA screening using RNA from cultured rat aortic VSMCs. The tissue specificity of expression of all of the cDNAs isolated was determined by Northern analysis. We isolated seven distinct cDNAs that were more strongly expressed in freshly dispersed, differentiated, aortic VSMCs compared with dedifferentiated late-passage cells. These were the cDNAs for tropoelastin, a matrix protein; alpha-smooth muscle (SM) actin, gamma-SM actin, calponin, and phospholamban, which are all proteins associated with the contractile function of differentiated VSMCs; SM22 alpha, a smooth muscle-specific protein of unknown function, and CHIP28, a putative membrane channel protein that is not highly expressed in other SM tissues and may therefore be a new VSMC marker. Two cDNAs that were expressed preferentially in late-passage dedifferentiated VSMCs were also isolated. These were the c...
CORRECTION
Authors: R M D Bernsen, J C van der Wouden
Journal: Thorax (2006)

We read the interesting study by Kinra et al 1 which gives us important information on the relationship between sibship size, birth order, and allergic disease in British students born in the first half of the 20th century. There are, however, a few points which we would like to raise:

(1) The authors observed a stronger association between sibship size and allergy in the oldest cohort and interpreted this finding as supporting the hygiene hypothesis because of a postulated larger difference in hygiene between larger and smaller families in this …
Comparison of Clinical Characteristics Between Clinical Trial Participants and Nonparticipants Using Electronic Health Record Data
Authors: James R. Rogers, Cong Liu, George Hripcsak, Ying Kuen Cheung, Chunhua Weng
Journal: JAMA Network Open (2021)

<h3>Importance</h3> Assessing generalizability of clinical trials is important to ensure appropriate application of interventions, but most assessments provide minimal granularity on comparisons of clinical characteristics. <h3>Objective</h3> To assess the extent of underlying clinical differences between clinical trial participants and nonparticipants by using a combination of electronic health record and trial enrollment data. <h3>Design, Setting, and Participants</h3> This cross-sectional study used data obtained from a single academic medical center between September 1996 and January 2019 to identify 1645 clinical trial participants from a diverse set of 202 available trials conducted at the center. Using an aggregated resampling procedure, nonparticipants were matched to participants 1:1 based on trial conditions, number of recent visits to a health care professional, and calendar time. <h3>Exposures</h3> Clinical trial enrollment vs no enrollment. <h3>Main Outcomes and Measures</h3> The primary outcome was standardized differences in clinical characteristics between participants and nonparticipants in clinical trials stratified into the 4 most common disease domains. <h3>Results</h3> This cross-sectional study included 1645 participants from 202 trials (929 [56.5%] male; mean [SD] age, 54.65 [21.38] years) and an aggregated set of 1645 nonparticipants (855 [52.0%] male; mean [SD] age, 57.24 [21.91] years). The most common disease domains for the selected trials were neoplastic disease (86 trials; 737 participants), disorders of the digestive system (31 trials; 321 participants), inflammatory disorders (28 trials; 276 participants), and disorders of the cardiovascular system (27 trials; 319 participants); trials could qualify for multiple disease domains. Among 31 conditions, the percentage of conditions for which the prevalence was lower among participants than among nonparticipants per standardized differences was 64.5% (20 conditions) for neoplastic disease trials, 61.3% (19) for digestive system trials, 58.1% (18) for inflammatory disorder trials, and 38.7% (12) for cardiovascular system trials. Among 17 medications, the percentage of medications for which use was less among participants than among nonparticipants per standardized differences was 64.7% (11) for neoplastic disease trials, 58.8% (10) for digestive system trials, 88.2% (15) for inflammatory disorder trials, and 52.9% (9) for cardiovascular system trials. <h3>Conclusions and Relevance</h3> Using a combination of electronic health record and trial enrollment data, this study found that clinical trial participants had fewer comorbidities and less use of medication than nonparticipants across a variety of disease domains. Combining trial enrollment data with electronic health record data may be useful for better understanding of the generalizability of trial results.
Phospholipid metabolism in cardiomyopathic hamster heart cells.
Authors: HKawaguchi, MShoki, HSano, TKudo, HSawa, HOkamoto, YSakata, HYasuda
Journal: Circulation Research (1991)

We demonstrated that the activities of phosphatidylinositide-specific phospholipase C, inositol 1,4,5-trisphosphate (IP3) kinase, and IP3 phosphatase were enhanced in cardiomyopathic hamster hearts (BIO 14.6 and BIO 53.58) in comparison to control hamsters (F1b). Release of both arachidonic acid and prostacyclin was markedly enhanced by norepinephrine in the cardiomyopathic hamsters. Phospholipase C in heart has high substrate specificity to phosphatidylinositol. IP3 production was markedly enhanced in the cardiomyopathic hamsters. We also determined the intracellular calcium concentration, which was higher in BIO 53.58 hamsters than in BIO 14.6 hamsters at 5-20 weeks of age. There was no significant difference in the intracellular calcium level between F1b and BIO 14.6 hamsters at 5 weeks of age. These results suggest that phosphatidylinositol turnover stimulated by norepinephrine may produce high intracellular calcium levels in both BIO 14.6 and BIO 53.58 myocytes. In addition, in BIO 53.58 hamsters, so...
Abstract 15052: Autonomic Neuromodulation Acutely Ameliorates Cardiac Mechanics in Humans: Results From the Neuromoduation to Reverse Diastolic Dysfunction (NERDD) Study
Authors: Stavros Stavrakis, Nicole Tran, Zain Asad, Khaled Elkholey, Sunny Po
Journal: Circulation (2018)

Introduction: Autonomic dysfunction, inflammation and diastolic dysfunction are prominent features of heart failure with preserved ejection fraction (HFpEF). We, and others have previously shown th...