Intra-atrial Pressure Research Articles

Staged Norwood operation for patients with hypoplastic left heart syndrome and cor triatriatum: a report of two cases

Two patients with hypoplastic left heart syndrome (HLHS) concomitant with cor triatriatum underwent the staged Norwood procedure following hybrid palliation. Cor triatriatum was diagnosed after birth in both cases. Case 1 with aortic stenosis and mitral atresia underwent bilateral pulmonary artery banding at 2 days of age. Subsequently, balloon atrial septostomy was conducted at 21 days of age due to hypoxia and increased intra-atrial pressure gradient. At 2 months of age, concomitant Norwood operation, cor triatriatum repair, and tricuspid valve repair were successfully performed. She has suffered from branch pulmonary artery hypoplasia since then; thus, Fontan operation was out of indication. Case 2 with aortic stenosis and mitral stenosis underwent bilateral pulmonary artery banding at 6 days of age. After that, the patient’s hemodynamic condition remained stable. The Norwood operation concomitant with cor triatriatum repair was performed at 2 months of age. However, during the procedure, massive pulmonary edema and hemorrhage occurred right after the initiation of cardiopulmonary bypass. She could not be weaned from cardiopulmonary bypass.

New concepts in heart failure with preserved ejection fraction and hypertension.

Hypertension (HTN) remains the most common and strongest contributing factor to the development of heart failure with preserved ejection fraction (HFpEF). In this review, we aim to summarize the pathophysiological processes linking HTN to HFpEF and highlight novel concepts in medical and device-based management of HFpEF and HTN. Despite the global increase in the prevalence of HFpEF, there has been limited benefit in current medication and device-based therapy for this complex syndrome. The hallmark of HFpEF is an elevated left intra-atrial and ventricular pressure and exertional dyspnea. Traditional medications used for treating HTN in patients with reduced left ventricular ejection fraction have unclear benefits in patients with HFpEF. Careful analysis of emerging medications such as angiotensin receptor-neprilysin inhibitor and sodium-glucose co-transporter-2 inhibitors showed benefit in reducing not only blood pressure but also hospitalizations in patients with HFpEF. Current data on device-based therapy aims to reduce left intra-atrial pressure, ventricular pressure and stimulate baroreceptors to lower blood pressure; however, needs further investigation. The nexus of HTN and HFpEF remains strong and complex. Although traditional medications for treating HFrEF did not affect long-term outcomes, novel therapies with angiotensin receptor neprilysin-inhibitor and sodium-glucose co-transporter-2 inhibitor offer promising results. Many device-based interventions in the HFpEF population are being developed with the aim to reduce left intra-atrial and ventricular pressure; however, their role in HFpEF hypertensive patients needs to be further investigated.

Indication and Technique of Ventriculo:Atrial Shunt for Normal Pressure Hydrocephalus

The type of shunt surgery with the best outcome and lowest complication rate has not been established. Ventriculo-atrial(V-A)shunts have almost been abandoned as the first choice of surgery. However, the V-A shunt has many advantages; the operative site is narrower than in other types of shunt surgery, and intra-atrial pressure is lower than intra-abdominal pressure, which may guarantee constant cerebrospinal fluid flow and less malfunction. Since this procedure has been neglected, devices of V-A shunt are scarce. Furthermore, the technique to insert an atrial catheter into the jugular vein is not commonly performed by general neurosurgeons. Herein, we introduce a simple method of V-A shunt for general neurosurgeons.

Implantation of an Innovative Intracardiac Microcomputer System for Web-Based Real-Time Monitoring of Heart Failure: Usability and Patients' Attitudes.

BackgroundHeart failure (HF) management guided by the measurement of intracardiac and pulmonary pressure values obtained through innovative permanent intracardiac microsensors has been recently proposed as a valid strategy to individualize treatment and anticipate hemodynamic destabilization. These sensors have potential to reduce patient hospitalization rates and optimize quality of life.ObjectiveThe aim of this study was to evaluate the usability and patients’ attitudes toward a new permanent intracardiac device implanted to remotely monitor left intra-atrial pressures (V-LAP, Vectorious Medical Technologies, Tel Aviv, Israel) in patients with chronic HF.MethodsThe V-LAP system is a miniaturized sensor implanted percutaneously across the interatrial septum. The system communicates wirelessly with a “companion device” (a wearable belt) that is placed on the patient’s chest at the time of acquisition/transmission of left heart pressure measurements. At first follow-up after implantation, the patients and health care providers were asked to fill out a questionnaire on the usability of the system, ease in performing the various required tasks (data acquisition and transmission), and overall satisfaction. Replies to the questions were mainly given using a 5-point Likert scale (1: very poor, 2: poor, 3: average, 4: good, 5: excellent). Further patient follow-ups were performed at 3, 6, and 12 months.ResultsUse and acceptance of the first 14 patients receiving the V-LAP technology worldwide and related health care providers have been analyzed to date. No periprocedural morbidity/mortality was observed. Before discharge, a tailored educational session was performed after device implantation with the patients and their health care providers. At the first follow-up, the mean score for overall comfort in technology use was 3.7 (SD 1.2) with 93% (13/14) of patients succeeding in applying and operating the system independently. For health care providers, the mean score for overall ease and comfort in use of the technology was 4.2 (SD 0.8). No significant differences were found between the patients’ and health care providers’ replies to the questionnaires. There was a general trend for higher scores in patients’ usability reports at later follow-ups, in which the score related to overall comfort with using the technology increased from 3.0 (SD 1.4) to 4.0 (SD 0.7) (P=.40) and comfort with wearing and adjusting the measuring thoracic belt increased from 2.8 (SD 1.0) to 4.2 (SD 0.4) (P=.02).ConclusionsDespite the gravity of their HF pathology and the complexity of their comorbid profile, patients are comfortable in using the V-LAP technology and, in the majority of cases, they can correctly and consistently acquire and transmit hemodynamic data. Although the overall patient/care provider satisfaction with the V-LAP system seems to be acceptable, improvements can be achieved after ameliorating the design of the measuring tools.Trial RegistrationClincalTrials.gov NCT03775161; https://clinicaltrials.gov/ct2/show/NCT03775161

THE MAN WITH THREE ATRIUMS: COR TRIATRIATUM SINISTER

SESSION TITLE: Medical Student/Resident Genetic and Developmental Disorders Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Cor triatriatum sinister (CTS) is a rare congenital cardiac condition characterized by the division of the left atrium by an abnormal fibromuscular membrane potentially causing obstruction of blood flow within the left atrium. The condition is found in less than 0.1% of patients diagnosed with cardiomyopathies and typically diagnosed in childhood. We describe a case of an incidentally diagnosed CTS in an adult. CASE PRESENTATION: A 45-year old male with a past medical history of supraventricular tachycardia and coronary artery disease status post percutaneous stenting was admitted to the hospital for evaluation of shortness of breath, productive cough, fever and chills. On chest x-ray, there was evidence of a left lower lobe pulmonary infiltrate and he was treated for community acquired pneumonia with ceftriaxone and azithromycin. His hospital course was complicated by hypoxemic respiratory failure. Echocardiography was performed, due to persistent tachycardia and shortness of breath and he was found to have CTS (Figure 1). On further questioning he declined a history of dyspnea on exertion, orthopnea or other respiratory complaints since childhood. He was discharged home after resolution of acute community-acquired pneumonia. DISCUSSION: There are three theories on the embryology of CTS; malincorporation, malseptation and entrapment. Among these, malincorporation of the common pulmonary vein into the left atrium creating two chambers separated by a narrowing chamber, is the most accepted theory. Up to 80% of cases are associated with other congenital abnormalities and presentation varies from asymptomatic patients to septic shock with pulmonary edema and respiratory failure. In adults, asymptomatic patients likely have a large foramen (fenestrations) with no intra-atrial pressure gradient unlike symptomatic patients who have no means for compensation and develop elevated left atrial pressure and subsequent pulmonary congestion. On physical exam, no pathognomonic findings are seen, and the absence of an opening snap or loud S1 differentiates the murmur of CTS from mitral stenosis. Echocardiography is a simple, non-invasive tool that can delineate the morphology and diagnose CTS as well as assess severity, describing severe obstruction when the doppler velocity gradient is greater than 2 m/s. Further studies are not needed, but cardiac catheterization, and cardiac magnetic resonance imaging can be useful for diagnosis and management. Management is based on symptoms and ranges from no treatment, to preload reducing agents, to surgical intervention. CONCLUSIONS: Establishing the diagnosis is critical as untreated, hemodynamically-significant CTS can lead to arrhythmias, pulmonary hypertension and right-sided heart failure that can be prevented with favorable outcomes after surgical correction. We present this case due to its rarity and asymptomatic nature in an adult patient. Reference #1: Nassar PN, Hamdan RH. Cor triatriatum sinistrum: classification and imaging modalities. The European journal of cardiovascular medicine. 2011;1(3):84. Reference #2: Ather B, Siddiqui WJ. Cor Triatriatum. In: StatPearls [Internet]. StatPearls Publishing; 2019. Reference #3: Chen Q, Guhathakurta S, Vadalapali G, Nalladaru Z, Easthope RN, Sharma AK. Cor triatriatum in adults: three new cases and a brief review. Tex Heart Inst J. 1999;26(3):206-210. DISCLOSURES: No relevant relationships by Israel Acosta Sanchez, source=Web Response No relevant relationships by Floyd Burke, source=Web Response No relevant relationships by Somshukla Ghosh, source=Web Response No relevant relationships by Hiren Patel, source=Web Response No relevant relationships by Irene Riestra Guiance, source=Web Response

Novel percutaneous interventional therapies in heart failure with preserved ejection fraction: an integrative review.

Heart failure with preserved ejection fraction (HFpEF) is a common disorder generating high mortality and important morbidity prevalence, with a very limited medical treatment available. Studies have shown that the pathophysiological hallmark of this condition is an elevated left intra-atrial pressure (LAP), exertional dyspnea being its clinical manifestation. The increasing pressure from LA is not based on volume overload (such as in heart failure with reduced ejection fraction) but on a diastolic left ventricular (LV) dysfunction combined with an inter-atrial dyssynchrony mimicking a pseudo-pacemaker syndrome. In this review, we aimed to summarize current knowledge and discuss future directions of the newest interventional percutaneous therapies of HFpEF. Novel interventional approaches developed to counter these mechanisms are as follows: LA decompression (inter-atrial shunt devices), enhancement of LV compliance (LV expanders), and inter-atrial resynchronization therapy (LA permanent pacing). To date, inter-atrial shunt devices (IASD) are the most studied, being the only devices currently tested in a phase 3 trial. Recent data showed that IASD are feasible, safe, and have a short-term clinical benefit in HFpEF patients. LV expanders and LA pacing therapy present with a smaller clinical benefit compared with IASD, but they are safe, without any major adverse outcomes currently noted. With further development and improvement of these mechanism-specific devices, it will be interesting to determine in the future whether a complex intervention of multiple HFpEF device implantation will be safe and have further benefits in HFpEF patients.

P wave peak time: A time window to evaluate left ventricular diastolic function.

The activation time from electrical signals to chamber conformational change has long been demonstrated to associate with LV performance and ventriculo-arterial coupling with prognostic implications in heart failure patients. P wave peak time (PWPT), an easily obtainable parameter from conventional surface electrocardiography, represents the time taken for excitation spreading from sinoatrial node to the maximal summation of positive deflection from both atria. Increased PWPT denotes prolonged intra- or inter-atrial conduction time and indicates elevated intra-atrial pressure. As shown in a recently published study, PWPT was highly correlated with LV end diastolic pressure (LVEDP) derived from direct measurement during cardiac catheterization. With its objective and easily obtainable nature, clinical application of PWPT to evaluate diastolic function can be expected, if more studies in different populations can confirm its clinical utility.

Orthogonal P-wave morphology is affected by intra-atrial pressures

BackgroundIt has previously been shown that the morphology of the P-wave neither depends on atrial size in healthy subjects with physiologically enlarged atria nor on the physiological anatomical variation in transverse orientation of the left atrium. The present study aimed to investigate if different pressures in the left and right atrium are associated with different P-wave morphologies.Methods38 patients with isolated, increased left atrial pressure, 51 patients with isolated, increased right atrial pressure and 76 patients with biatrially increased pressure were studied. All had undergone right heart catheterization and had 12-lead electrocardiographic recordings, which were transformed into vectorcardiograms for detailed P-wave morphology analysis.ResultsNormal P-wave morphology (type 1) was more common in patients with isolated increased pressure in the right atrium while abnormal P-wave morphology (type 2) was more common in the groups with increased left atrial pressure (P = 0.032). Moreover, patients with increased left atrial pressure, either isolated or in conjunction with increased right atrial pressure, had significantly more often a P-wave morphology with a positive deflection in the sagittal plane (P = 0.004).ConclusionIsolated elevated right atrial pressure was associated with normal P-wave morphology while left-sided atrial pressure elevation, either isolated or in combination with right atrial pressure elevation, was associated with abnormal P-wave morphology.

Characteristics of PR interval as predictor for atrial fibrillation: association with biomarkers and outcomes.

The PR interval may be considered as a simple and easily obtainable predictor for adverse events, including atrial fibrillation (AF), pacemaker implantation, and mortality. Interestingly, both high and low extremes of the PR duration are associated with AF risk. However, the results regarding PR prolongation as a risk factor for AF are inconsistent. Some studies have analyzed the impact of P duration (as a part of the PR interval) and demonstrated that the P-duration contributes to the length of PR interval and adverse outcomes. The PR prolongation could be considered as a marker for cardiovascular degenerative aging caused by myocardial fibrosis and vascular inflammation. Furthermore, due to PR prolongation chronically raised intra-atrial pressure and consequential neuro-hormonal activation predispose systemic vascular endothelial dysfunction and explain the associations with adverse vascular events. In this review, we discuss the association between biomarkers with PR interval in AF.

Shear Stress Induces Transverse Ca2+ Waves via Autocrine Activation of P2X Purinoceptors in Rat Atrial Myocytes

Atrial myocytes are exposed to high shear stress during blood regurgitation and high intra-atrial pressure due to valve diseases and heart failure, since such disturbances disrupt endocardium. We have previously reported that shear stress induces two types of global Ca2+ waves in atrial myocytes, longitudinal and transverse Ca2+ waves (T-waves) (Biophys J 2012;102(3, Suppl 1);227a), and that the longitudinal wave is triggered by Ca2+ release via P2Y1 purinoceptor-inositol 1,4,5-trisphosphate receptor signaling (J Physiol 2015;593:5091-5109). Here, we investigated cellular mechanism for the generation of T-wave in atrial cells under shear stress. Shear stress of ∼16 dyn/cm2 was applied onto single myocytes using micro fluid-jet, and two-dimensional confocal Ca2+ imaging was performed. Shear stress-induced T-waves were observed repetitively under 3-4 min intervals between the stimuli, and occurred at ∼1 event per 10 s. They were eliminated by inhibition of the voltage-gated Na+ or Ca2+ channels, or ryanodine receptors, suggesting that the T-wave is mediated by action potential-triggered Ca2+ release. Blockades of key stretch signaling molecules, stretch-activated channel, Na+-Ca2+ exchange, and NADPH oxidase, did not suppress T-wave generation by shear. However, shear-induced T-wave generation was abolished by pre-incubation of cells with external ATP-metabolizing enzyme apyrase, the gap junction blocker carbenoxolone, or with P2X purinoceptor antagonist iso-PPADS. Inhibition of P2Y1 purinergic signaling that mediates the longitudinal Ca2+ wave under shear did not attenuate the occurrence of T-waves. Our data suggest that shear stress induces activation of P2X purinoceptors via gap junction-mediated ATP release, thereby triggering action potential with subsequent T-wave in atrial myocytes.

The role of gap junctions in stretch-induced atrial fibrillation.

AimsThe aim of this study was to investigate the role of gap junctions in atrial fibrillation (AF) by analysing the effects of a gap junction enhancer and blocker on AF vulnerability and electrophysiological properties of isolated hearts.Methods and resultsThe acute atrial stretch model of AF in the isolated rabbit heart was used. Sustained AF (SAF) was induced by a burst of high-frequency stimulation of the Bachmann's bundle. The effective refractory period (ERP) was measured, and the total conduction time (TCT) and the pattern of conduction of the anterior surface of the left atrium were monitored by using an optical mapping system. The effect of enhancing gap junction function by 100–1000 nM rotigaptide (ZP123) and block by 30 μM carbenoxolone on these parameters was measured. SAF inducibility was increased with an elevation of intra-atrial pressure. Enhanced gap junction conductance induced by treatment with 100–1000 nM rotigaptide reduced SAF inducibility, and the gap junction blocker carbenoxolone increased SAF inducibility. In the absence of gap junction enhancer or blocker, normal conduction was observed at 0 cmH2O. When intra-atrial pressure was raised to 12 cmH2O, the conduction pattern was changed to a heterogeneous zig-zag pattern and TCT was prolonged. Conduction pattern was not affected by either agent. Rotigaptide shortened TCT, whereas carbenoxolone prolonged TCT. ERP was significantly shortened with an increase in intra-atrial pressure, but ERP was unaffected by either agent.ConclusionGap junction modulators changed AF inducibility through their effects on atrial conduction, not by altering ERP.

MR-proANP improves prediction of mortality and cardiovascular events in patients with STEMI.

Atrial natriuretic peptide (ANP) is released from the atria (on cleavage of proANP) in response to elevated intra-atrial pressure and wall stretch. Clinical data on proANP are still limited, mainly due to limitations in assaying the protein, which recently have been solved. ProANP is elevated in cardiovascular disease and predicts outcome in heart failure. However, knowledge of the prognostic value in acute myocardial infarction remains limited. We prospectively included 680 patients with STEMI treated with primary-PCI, from September 2006 to December 2008. Blood samples were drawn immediately before PCI. Plasma MR-proANP was measured using an automated processing assay. Endpoints were all-cause mortality (n = 137) and the combined endpoint (n = 170) of major adverse cardiovascular events (MACE) defined as cardiovascular mortality and admission due to recurrent MI, ischaemic stroke or heart failure. During 5-year follow-up, MR-proANP was associated with increased risk of all-cause mortality and MACE (both p < 0.001). After adjustment for confounding risk factors (age, gender, hypertension, diabetes, hypercholesterolaemia, smoking, previous MI, BMI, eGFR, CRP, peak-TnI, symptom-to-balloon time, multivessel disease, complex lesion, LAD-lesion and use of glycoprotein inhibitor), MR-proANP remained an independent predictor of all-cause mortality and MACE - hazard ratio: 1.68 (95% CI 1.35-2.10; p < 0.001) and 1.68 (95% CI 1.39-2.03; p < 0.001) per standard deviation increase in MR-proANP. MR-proANP significantly increased C-statistics and reclassified 26% of the patients for all-cause mortality and 34% for MACE into higher or lower risk categories, matching actual event rates more accurately. Plasma MR-proANP independently predicts all-cause mortality and MACE in patients with STEMI.

The haemodynamic cascade

The haemodynamic cascade

Prognostic implication of atrial pressures in patients with nonvalvular atrial fibrillation and preserved systolic function who undergo radiofrequency catheter ablation: a pilot study

Patients with left ventricular (LV) diastolic dysfunction have a worse prognosis after the radiofrequency ablation (RFA) of atrial fibrillation (AF) than subjects with normal LV function [1,2]. In those patients, noncompliant LV increases LV end-diastolic pressure and left atrial (LA) pressure; consequently, intra-atrial pressure overload induces atrial remodeling by a stretch-related mechanism and these atria serve as a pathological substrate of AF [3]. We evaluated (1) the relationship between both atrial pressure and atrial volume in nonvalvular AF and (2) the impact of both atrial pressures on the recurrence of AF after RFA.

Ectopic and reentrant activation patterns in the posterior left atrium during stretch-related atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans and is predicted to dramatically increase its prevalence in the future. There is experimental evidence that increasing stretch increases the dominance of the pulmonary veins (PVs) during AF in isolated hearts and ectopic activity in the isolated PVs, but the ionic mechanisms underlying such effects are not clear and the ability of the PVs to favorably host functional reentry during stretch cannot be excluded. We used a combination of endocardial–epicardial optical mapping with phase and spectral analysis to study stretch-related AF (SRAF) in normal isolated sheep hearts. We have found rapid AF sources in the posterior left atrium (PLA) and PV region and their activation frequency and level of organization correlated with intra-atrial pressure. Analysis of the surfaces' optical mapping data in the phase domain reveals that activation of the PLA consisted of alternating patterns of breakthroughs, reentries and relatively simple waves swiping across the mapped field. The patterns on the endocardial and epicardial PLA surface at any given moment of time of the SRAF could be either identical or not identical, and the activity in the thickness of the PLA wall is hypothesized to conform to either ectopic discharge or scroll waves, but a definite evidence for the presence of such mechanisms is currently lacking. Thus the understanding of the manner by which the mechano-electric feedback effects in the PLA, including the PVs, become important in the initiation and maintenance of AF requires further detailed investigation.

High-Resolution Endocardial and Epicardial Optical Mapping in a Sheep Model of Stretch-Induced Atrial Fibrillation

Atrial fibrillation (AF) is a complex cardiac arrhythmia with high morbidity and mortality.(1,2) It is the most common sustained cardiac rhythm disturbance seen in clinical practice and its prevalence is expected to increase in the coming years.(3) Increased intra-atrial pressure and dilatation have been long recognized to lead to AF,(1,4) which highlights the relevance of using animal models and stretch to study AF dynamics. Understanding the mechanisms underlying AF requires visualization of the cardiac electrical waves with high spatial and temporal resolution. While high-temporal resolution can be achieved by conventional electrical mapping traditionally used in human electrophysiological studies, the small number of intra-atrial electrodes that can be used simultaneously limits the spatial resolution and precludes any detailed tracking of the electrical waves during the arrhythmia. The introduction of optical mapping in the early 90's enabled wide-field characterization of fibrillatory activity together with sub-millimeter spatial resolution in animal models(5,6) and led to the identification of rapidly spinning electrical wave patterns (rotors) as the sources of the fibrillatory activity that may occur in the ventricles or the atria.(7-9) Using combined time- and frequency-domain analyses of optical mapping it is possible to demonstrate discrete sites of high frequency periodic activity during AF, along with frequency gradients between left and right atrium. The region with fastest rotors activates at the highest frequency and drives the overall arrhythmia.(10,11) The waves emanating from such rotor interact with either functional or anatomic obstacles in their path, resulting in the phenomenon of fibrillatory conduction.(12) Mapping the endocardial surface of the posterior left atrium (PLA) allows the tracking of AF wave dynamics in the region with the highest rotor frequency. Importantly, the PLA is the region where intracavitary catheter-based ablative procedures are most successful terminating AF in patients,(13) which underscores the relevance of studying AF dynamics from the interior of the left atrium. Here we describe a sheep model of acute stretch-induced AF, which resembles some of the characteristics of human paroxysmal AF. Epicardial mapping on the left atrium is complemented with endocardial mapping of the PLA using a dual-channel rigid borescope c-mounted to a CCD camera, which represents the most direct approach to visualize the patterns of activation in the most relevant region for AF maintenance.

Is the oscillometric blood pressure measuring device in accord with the intra-arterial invasive blood pressure measuring method?

Objectives The use of automatic blood pressure measuring devices with oscillometric method is popular in home and clinics. Although the protocol for evaluating the accuracy of devices was known, subject of validation was not real user who has cardiovascular risk factor. In this study, we try to verify the BP measured with automatic oscillometric device with invasively measured intra-atrial blood pressure especially in older and multiple cardiovascular risk factors. Design and methods From September 2007 to April 2008 in Chungbuk National University Hospital 104 men and women between 35 and 82years of age with coronary angiography approached with radial artery were included.

Development of a toolbox for electrocardiogram-based interpretation of atrial fibrillation

Background Atrial fibrillation (AF) develops as a consequence of an underlying heart disease such as fibrosis, inflammation, hyperthyroidism, elevated intra-atrial pressures, and/or atrial dilatation. The arrhythmia is initiated by, or depends on, ectopic focal activity. Autonomic dysfunction may also play a role. However, in most patients, the actual cause of AF is difficult to establish, which hampers the selection of the optimal mode of treatment. This study aims to develop tools for assisting the physician's decision-making process. Methods Signal analytical methods have been developed for optimizing the assessment of the complexity of AF in all of the standard 12-lead signals. The development involved an evaluation of methods for reducing the signal components stemming from the electric activity of the ventricles (QRST suppression). The methods were tested on simulated recordings, on clinical recordings on patients in AF, and on patients exhibiting atrial flutter (AFL) and atrial tachycardia. The results have been published previously. Subsequently, the implementation of the algorithms in a commercially available electrocardiogram (ECG) recorder, an implementation referred to as its AF-Toolbox, has been carried out. The performance of this implementation was tested against those observed during the development stage. In addition, an improved visualization of the specific ECG components was implemented. This was enabled by providing a separate view on ventricular and atrial activity, which resulted from the steps implied in the QRST suppression. Furthermore, a search was initiated for identifying meaningful features in the cleaned up atrial signals. Results When testing the implementation of the previously developed methods in the Toolbox on simulated and clinical data, the suppression of ventricular activity in the ECG produced residuals down to the level of physiologic background noise, in agreement with those reported on previously. The QRST suppression resulted in a better visualization of the atrial signals in AF, atrial AFL, sinus rhythm in the presence of atrioventricular blocks, or ectopic beats. Classifiers for AF and AFL that have been defined so far include the distinct spectral components (multiple basic frequencies), exhibiting distinct dominance in specific leads. The annotations of ventricular and atrial activities, ventricular and atrial trigger, as well as ratio between atrial and ventricular rates were greatly facilitated. The time diagram of ventricular and atrial triggers provides an additional view on rhythm disturbances. Conclusions The AF-Toolbox that is currently developed for clinical applications has the potential of reliably detecting and classifying AF, as well as to correctly describe atrioventricular conduction, propagation blocks and/or ectopic beats. Based on the results obtained, a first industrial prototype has been built, which will be used to assess its performance in a routine clinical environment. The availability of this tool will facilitate the search for meaningful signal features for identifying the source of AF in individual patients.

Effect of Cardiac Tamponade on Plasma Concentrations of Atrial Natriuretic Peptide (ANP) in Calves

To study the effect of cardiac tamponade on plasma concentrations of atrial natriuretic peptide (ANP) female calves received an infusion of 450 ml of 0.9% saline into the pericardial space. This was accompanied by a parallel rise in both, right atrial pressure (from 4.5 +/- 2.6 mm Hg to 14.1 +/- 3.8 mm Hg (p less than 0.01] and in intrapericardial pressure (from 0.4 +/- 2.0 mm Hg to 12.9 +/- 3.9 mm Hg (p less than 0.01] and a fall in cardiac output from 11.4 +/- 1.9 l/min to 8.5 +/- 2.4 l/min (p less than 0.01). Plasma concentrations of ANP remained unchanged in 7 of 9 experiments. During these seven experiments plasma concentrations of renin and aldosterone increased from 0.65 +/- 0.27 X 10 E-4 GU/ml to 1.04 +/- 0.43 X 10 E-4 GU/ml (p less than 0.01) and from 2.7 +/- 0.9 ng/dl to 11.4 +/- 6.1 ng/dl (p less than 0.01), respectively. On two occasions, which were characterized by an excessive fall in cardiac output (to less than 40% of initial values) cardiac tamponade was followed by an extensive rise in the plasma concentrations of ANP, renin and aldosterone. These results indicate that an increase in intra-atrial pressure per se is not the decisive factor in the control of ANP secretion. Since atrial transmural pressure does not change during cardiac tamponade ANP concentrations are, as a rule, unaltered by that condition. An increase in plasma ANP is seen only during preshock hemodynamic conditions possibly due to a reduced intra-atrial volume.

Regulation of ANP secretion from isolated atria by prostaglandins and cyclooxygenase-2

Cyclooxygenase (COX) is a key enzyme regulating the production of various prostaglandins (PGs) from arachidonic acid. Angiotensin II has been reported to be an important inflammatory mediator, which increases COX-2. The aim of this study was to determine the role of various PGs and COX-2 in the regulation of atrial natriuretic peptide (ANP) secretion. PGF2α and PGD2 caused dose-dependent increases in ANP release and intra-atrial pressure. The potency for the stimulation of ANP secretion by PGF2α was higher than that by PGD2. In contrast, PGE2, PGI2, PGJ2, and thromboxane A2 did not show any significant effects. The increases in intra-atrial pressure and ANP secretion induced by PGF2α and PGD2 were significantly attenuated by the pretreatment with an inhibitor of PGF2α receptor. By the pretreatment with an inhibitor for phospholipase C (PLC), inositol 3-phosphate (IP3) receptor, protein kinase C (PKC), or myosin light chain kinase (MLCK), PGF2α-mediated increase in ANP secretion and positive inotropy were attenuated. Inhibitor for COX-1 or COX-2 did not cause any significant effects on atrial parameters. In hypertrophied rat atria, PGF2α-induced positive inotropy and ANP secretion were markedly attenuated whereas COX-2 inhibitor stimulated ANP secretion. The expression of COX-2 increased and the expression of PGF2α receptor mRNA decreased in hypertrophied rat atria. These results suggest that PGF2α increased the ANP secretion and positive inotropy through PLC–IP3–PKC–MLCK pathway, and the modulation of ANP secretion by COX-2 inhibitor and PGF2α may partly relate to the development of renal hypertension.