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PubMed2002

Secretory component, J chain, and immunoglobulins in human embryos and fetuses of the first trimester of pregnancy: immunohistochemical study.

In our previous studies, we described the development of the secretory (mucosal) immune system (SIS) in human fetuses in the second trimester of pregnancy. In the present study, we examined the presence and distribution of components of this system in human embryos and early fetuses in the first trimester. An immunohistochemical study was performed on 17 embryos and 9 fetuses (4 to 12 wk of development) using antibodies against secretory component (SC), joining (J) chain, immunoglobulins (IgA, IgM, IgG), subsets of T and B lymphocytes, and macrophages. Cells positive for SC, J chain, and IgG were found in epithelial tissues from wk 4 of pregnancy. In the internal organs, such as the myocardium and endocardium, capillary endothelium, epithelium of the kidney tubules and some others, only J chain and immunoglobulins were seen. IgA was weakly reactive in tissues where SC and/or J chain were presented. IgM was very weak or absent. Among the cellular components of the SIS, only macrophages were seen in 4-wk-old embryos. CD3+ and CD20+ lymphocytes were found at wk 7 to 8. IgA- and IgM-positive lymphocytes appeared at the end of wk 9. The SIS is widespread in embryonic and early fetal periods and begins to function before the appearance of the common immune system in the developing organism. The first functional components of the SIS, such as IgG and IgA observed in this study, are most probably of maternal origin.

Adult↗
PubMed2005

Tricuspid endocarditis in an adult patient with Ebstein's anomaly who has a residual pacemaker lead.

Ebstein's anomaly is defined as an apical displacement of the attachment of the septal tricuspid valve leaflet from the right atrioventricular annulus that exceeded 1.2 cm in length. Patients with Ebstein's anomaly are known to have a high potential for developing arrhythmia, in the vast majority, of the tachycardia type. Infective endocarditis is characterized by ulcerovegetational lesions that result from the graft of a microorganism, usually bacterial, on the valvuler endocardium (native valve endocarditis) or on a prosthesis (prosthetic valve endocarditis). Ebstein's anomaly with tricuspid regurgitation is also thought to be a predisposing condition for infective endocarditis. In this case, we report a patient who presented with atrial flutter and infective endocarditis due to residual pacemaker lead and Ebstein's anomaly.

Device Removal↗
PubMed2005

Performance of user independent echocardiographic border detection algorithm: comparison with human observer variability.

INTRODUCTION: We evaluated a method for autonomous, user-independent automated border delineation (ABD) developed by Geiser and Wilson, by comparing the accuracy of ABD relative to manual border tracing. METHODS: Short axis echocardiographic images of 84 patients from 3 clinical sites were analyzed using ABD and by manual tracing performed by two observers at each site and two observers at a core laboratory. The centerline method was used to measure the distance between each pair of computer-generated and hand-traced borders. Cardiac parameters were also measured from all sets of borders: LV area, fractional area change, antero-posterior diameter, wall motion, and wall thickening. RESULTS: The distance between computer-generated and hand-traced borders was slightly but significantly greater than human interobserver variability between the clinical sites and the core laboratory (0.34+/-0.25 (N = 328) vs. 0.26+/-0.16 (N = 320) cm for the endocardium at end diastole, p = 0.0001). Measurements of LV area and fractional area change were similar by ABD and manual tracing. Other cardiac parameters showed greater deviation between ABD and manually traced borders than between human observers. CONCLUSION: Autonomous ABD provides accurate measurements of LV area and area-derived indices. However measurements dependent on border point location deviate more by ABD.

Algorithms↗
PubMed2005

Electrical stimulation to identify neural elements on the heart: their role in atrial fibrillation.

EXPERIMENTAL STUDIES: Anesthetized dogs were subjected to a right then left thoracotomy. Two modes of electrical stimulation were used to activate ganglionated plexi (GP) on the epicardium of the atria: (1) Near the base of each pulmonary vein (PV), trains of high frequency stimuli (HFS) were coupled to each atrial paced beat so as to fall within the refractory period to achieve nerve stimulation without atrial excitation; and (2) Continuous HFS was applied via plaque electrodes sutured to epicardial fat pads (containing a GP) near the right superior (RS) and left superior (LS) PVs. The chest was then closed. An ablation catheter, inserted percutaneously, was positioned fluoroscopically in the right atrium across from the epicardial plaque electrode near the RSPV. Transeptal puncture was used to place an ablation catheter at the LSPV-left atrial junction. HFS applied to each of the epicardial fat pads induced atrial fibrillation (AF) and also caused high grade AV block due to a strong parasympathetic effect on the AV node. Radiofrequency ablation from the right and left atrial endocardium abolished the vagal response to HFS delivered to the plaque electrodes on the fat pads close to the RSPV and LSPV, respectively. CLINICAL STUDIES: Sixty (60) patients with paroxysmal or persistent AF underwent PV antrum isolation (27 patients) or PV antrum isolation plus left atrial GP ablation (33 patients). Endocardial HFS at the border of the PV antra near the 4 GPs produced AF and high grade AV block (vagal response) during AF. RFA at these sites abolished the vagal response. Testing in a small number of patients with very short follow-up suggests that adding GP ablation to PV antrum isolation may increase ablation success (absence of AF recurrence) from 70% to 91%. CONCLUSIONS: These basic and clinical studies suggest that localized cardiac autonomic ganglia (GPs) may play a critical role in the initiation and maintenance of AF.

Animals↗
PubMed2005

Catheter location, tracking, cardiac chamber geometry creation, and ablation using cutaneous patches.

OBJECTIVE: The ability to construct a three-dimensional (3-D) surface model of the endocardium and track the location of catheters within a cardiac chamber, using only cutaneous patches, would be a useful advancement in treating arrhythmias. We tested the feasibility of such a system, Ensite NavX (Endocardial Solutions, Inc., St. Paul, MN, USA), in patients undergoing catheter ablation for SVTs. METHODS: Sixteen patients with 20 arrhythmias undergoing ablation were selected. Skin electrode patches were placed on the chest to create a 3-D coordinate system. A low-amplitude, 5.7 kHz signal emitted from the patches was received by conventional catheters positioned in the heart. Catheter location was determined by measuring the field strength received by the catheters. Location points were successively acquired while catheters were moved throughout the chamber. This information was collected and processed by a workstation to create a detailed 3-D model of the endocardial surface. Anatomic landmarks were labeled on the model as the mapping catheter was navigated. 3-D cardiac chamber geometry reconstruction, landmark labeling, and real time catheter tracking were performed successfully in all patients. Up to six catheters, with a total of up to 26 intracardiac electrodes, were tracked simultaneously. RESULTS: Constructed geometries, including major vessels and valves, correlated closely with traditional anatomic models as well as intracardiac recordings and fluoroscopic images. CONCLUSIONS: Real-time catheter tracking and 3-D cardiac chamber model construction is feasible using cutaneous patches and conventional catheters. This approach may be useful in the treatment of patients with cardiac arrhythmias where ablation therapy is primarily anatomically based.

Adult↗
PubMed2000

Strategies for catheter ablation of scar-related ventricular tachycardia.

Ventricular tachycardia (VT) due to reentry in and around regions of ventricular scar from an old myocardial infarction or cardiomyopathic process is often a difficult management problem. Radiofrequency catheter ablation is an option for controlling frequent VT episodes. Patient and VT characteristics determine the mapping and ablation approach and efficacy. In patients with a VT that is hemodynamically tolerated to allow mapping, prevention of recurrent VT is achieved in 54% to 66% of patients with a procedure related mortality of 1% to 2.7%. Multiple morphologies of monomorphic VT and circuits that are located deep to the endocardium are common problems that reduce efficacy. Mapping to identify target regions for ablation can be difficult if VT is rapid and not tolerated, or not inducible. Ablation of these "unmappable VTs" by designing ablation lines or areas based on the characteristics of the scar as assessed during sinus rhythm, and using approaches to assess global activation from a limited number of beats has been shown to be feasible. Ablation of multiple VTs, epicardial VTs, and poorly tolerated VTs are feasible. Future studies defining efficacy and risks are needed.

Body Surface Potential Mapping↗
PubMed1999

Recent advances in cardiac mapping techniques.

Recently several new mapping modalities have been introduced into clinical electrophysiologic laboratories, including basket catheter mapping, electromagnetic mapping, and noncontact mapping. In addition, intracardiac echocardiography is being used increasingly to visualize important intracardiac structures for catheter ablation. Basket catheter mapping and noncontact mapping are simultaneous mapping devices, whereas electromagnetic mapping is a sequential mapping tool. The new basket-shaped catheters provide up to 64 electrodes mounted on a variable number of splines that encircle the cardiac contour. Animation programs help in identifying the earliest activation and analyzing the activation sequence. Electromagnetic mapping uses low density magnetic fields to navigate the catheter position and to allow nonfluoroscopic mapping and ablation. Sequential recording of intracardiac potentials produces a real-time, color-coded, three-dimensional activation map. Noncontact mapping does not require direct contact with the endocardium and permits the reconstruction of more than 3000 simultaneous computed electrograms via mathematical algorithms. Three-dimensional isopotential maps are generated to visualize the impulse propagation and guide catheter ablation.

Algorithms↗
PubMed2001

Outpatient Management of Infective Endocarditis.

Because of unique host defense characteristics of the endocardium, successful therapy for infective endocarditis (IE) has necessitated bactericidal antimicrobial agents, generally administered in high doses for prolonged periods of time. This has required therapy in the hospital setting. However, in recent years, it has become apparent that outpatient therapy is feasible if appropriate agents can be administered at home, for example, using either home parenteral therapy or oral preparations. Over the past few decades, there has been a trend toward reducing inpatient reimbursement for various conditions, including serious infections. The decision to treat IE on an outpatient basis is made more easily if based on previous published experience. Published reports have concluded that outpatient therapy is more appropriate for "uncomplicated" IE caused by relatively susceptible microorganisms. The purpose of this paper is to review data describing the results of management of IE in the outpatient setting.

Journal Article↗
PubMed2002

Platelets and Platelet Inhibitors in Infective Endocarditis.

The pathogenesis of infective endocarditis depends on complex interactions between the causative pathogen, plasma proteins, platelets, and vascular endothelial cells. In addition to being the main target of bacteria in the initial stage of bacterial adherence to the endocardium, platelets now appear to play an important role in antimicrobial host defense against endocarditis through the secretion of so-called platelet microbicidal proteins. In animal models of endocarditis, low-dose aspirin was shown to significantly reduce the vegetation weight, the bacterial density of vegetation, the hematogenous bacterial dissemination, and the frequency of embolic events. However, these facts cannot be extrapolated to clinical care in humans, since to date, there is no definitive proof of the adjunctive benefit of aspirin in human infective endocarditis.

Journal Article↗
PubMed2002

[Radiofrequency catheter ablation of ventricular tachycardias].

Management of patients with ventricular tachycardia (VT) is often difficult. Drug therapy is often ineffective. Implantable cardioverter defibrillators (ICDs) can terminate VT episodes but do not prevent them. Radiofrequency (RF) catheter ablation can suppress arrhythmias in selected patients. However, the procedure is often challenging and success rates lower than for ablation of supraventricular tachycardias. The mapping and ablation approach depends on the VT mechanism. Monomorphic VT in patients without structural heart disease is referred to as idiopathic and has a focal origin. These VTs can be abolished by ablation in most of the patients. In VT due to reentry within an area of scar from an old myocardial infarction or cardiomyopathic process, critical parts of the circuit may be difficult to localize, rendering RF ablation challenging. In patients with monomorphic VT, prevention of VT recurrence can be achieved in 55% to 80% of patients. Multiple morphologies of VTs and circuits that are located deep in the endocardium are common problems that reduce efficacy. Furthermore, mapping to identify target regions for ablation can be more difficult if VT is rapid and not tolerated, or not inducible. Recently, multisite mapping of the arrhythmia substrate during sinus rhythm or multisite activation mapping of a few VT beats were shown to be effective for ablation of these "unmappable VTs". Bundle branch reentry tachycardia occur in patients with nonischemic cardiomyopathies, mostly valvular heart disease and can be successfully abolished with RF ablation of the right bundle. However, some of these patients may develop recurrences due to other types of VT. Recent technical developments have increased efficacy and simplified the approach of RF ablation of VT in patients with structural heart disease. However, long-term efficacy is not accurately predictable and implantation of an ICD is mandatory in most of the patients with severely depressed left ventricular function.

Cardiomyopathy, Dilated↗
PubMed1978

The influence of atrial systole on ventricular capture by failing artificial pacemakers. II. Experimental observations.

The mechanism by which atrial systeole influences the efficacy of ventricular capture by a failing pacemaker was investigated in 12 dogs with atrioventricular heart block. Atrial systole caused facilitation of ventricular capture in eight dogs, and inhibition of capture in 10 dogs. Interpolating atrial extrasystoles caused an enhancement or depression of the hemodynamic performance of the atrial systole that affected the efficacy of the pacemaker stimulus. These interpolation experiments showed that atrial systole influenced the efficacy of capture by a mechanical mechanism and not by an electrotonic mechanism. Atrial systole probably caused motion of the endocardial pacing catheter and/or ventricular myocardium. This motion increased or decreased the contact between the pacing electrode and the endocardium with subsequent changes in the efficacy of capture. In three dogs with pacing through epicardial electrodes, atrial systole had no effect on the efficacy of capture.

Animals↗
PubMed1982

Factors related to vulnerability to arrhythmias in acute myocardial infarction.

Ion-selective electrodes designed in our laboratory have been employed to determine the characteristics of the changes in extracellular K+ and pH associated with acute coronary artery ligation and release. These studies have defined major inhomogeneities in the rate and magnitude of change of extracellular K+ and pH not only at the lateral margin of the ischemic zone but also between the subepicardium and subendocardium, between the subendocardium and endocardium, and even between closely spaced electrodes throughout the ischemic zone. The inhomogeneities during reperfusion were as great as or greater than those induced by coronary ligation. We have used papillary muscles of guinea pigs to determine the effect of the various combinations of extracellular pH and K+ observed at any point in time in an intact heart to study the anticipated changes in conduction and have found both a speeding and a slowing of conduction, which can be expected to occur simultaneously in an intact heart. These results indicate that significant inhomogeneities exist in the ionic and electrical consequences of acute coronary artery ligation and release and that these inhomogeneities can be expected to result in disorders of conduction leading to reentry.

Animals↗
PubMed1982

Echographic-quantified severity of mitral anulus calcification: prognostic correlation to related hemodynamic, valvular, rhythm, and conduction abnormalities.

Clinical and echocardiographic findings in 123 patients with mitral anulus calcification (MAC) were analyzed. In all patients M-mode echocardiography demonstrated a dense band of echoes posterior to the mitral valve, moving parallel and anterior to the left ventricular endocardium. Thirty-three per cent of patients were classified as having minimal to mild MAC (< 5 mm) and 67% had moderate to severe MAC (greater than or equal to 5 mm). There was a significant correlation between the degree of MAC to left atrial enlargement, congestive heart failure, aortic valve sclerosis, mitral regurgitation, atrial fibrillation, and AV-fascicular conduction defects. ECG evidence of conduction disturbances was significantly associated with MAC greater than or equal to t mm in width. The echocardiographic demonstration of MAC greater than or equal to 5 mm was significantly associated with the clinical implications known to occur with MAC; this echographic finding has important prognostic value in the evaluation of patients with mitral anulus calcification.

Aged↗
PubMed1983

Cardiac damage in dogs with chronically implanted automatic defibrillator electrode catheters and given four episodes of multiple shocks.

In 14 dogs, a newly designed automatic defibrillator electrode catheter with paired ventricular and superior vena caval electrodes was implanted transvenously into the right ventricular (RV) apex for 26 weeks. Twelve dogs were given multiple (mean total = 21.3) near-threshold (mean delivered energy = 17.6 joules) shocks via the lead at 0, 5, 12, and 26 weeks after implantation. Two days after the last shocks, the dogs were killed and the cardiac alterations were evaluated at necropsy and by histopathology. The lead induced mild to moderate cardiac alterations of (1) endocardial fibrosis, either as flat or papillary lesions, and of (2) segments of smooth thin fibrous sheath formation over the lead with adhesions to the adjacent endocardium. Mild cardiac alterations were induced by the shocks including myocardial necrosis and calcification, concentrated in the ventricular septum and RV free wall adjacent to the ventricular electrodes, and foci of postnecrotic fibrosis. The chronically implanted lead was determined to be safe and effective in dogs.

Animals↗
PubMed1983

Rapid, semiautomated technique for estimating left ventricular volume.

A new system for rapidly quantitating left ventricular volume using two-dimensional echocardiography is tested. This system relies on a microprocessor built into a sector scanner that immediately calculates the length, area, and volume of the chamber being imaged using the mathematical model of an ellipsoid of revolution. The calculations are made after the observer superimposes a smooth calibrated ellipse outline on the endocardium imaged with the sector scanner. We report our experience with this system in 50 patients with a variety of cardiac disorders and compare the left ventricular volumes measured with those obtained using cineangiography, M-mode, and more detailed light pen tracing techniques. Correlations between volumes measured with the elliptical calipers and angiography were good (r = 0.820, SEE +/- 38.8 ml) (n = 100), but not as good as that between light pen tracing of the echo images and angiography (r = 0.847, SEE +/- 27.8 ml) (n = 22). M-mode correlated less well with angiography (r = 0.789; SEE +/- 42.1 ml) (n = 90). We conclude that the calibrated ellipse system is rapid and simple to use, while its accuracy matches previous studies using two-dimensional echocardiography to quantitate left ventricular volume.

Cardiovascular Diseases↗
PubMed1984

Electrophysiologic and hemodynamic effects of propafenone, a new antiarrhythmic agent, on the anesthetized, closed-chest dog: comparative study with lidocaine.

The relative hemodynamic and electrophysiologic effects of a new antiarrhythmic drug, propafenone, and lidocaine were evaluated in eight closed-chest, anesthetized dogs. Propafenone (4 mg/kg intravenously) significantly (p less than 0.05) lowered aortic and pulmonary systolic pressures and caused a rise in heart rate (p less than 0.05). Cardiac output decreased from 4.5 +/- 1 to 3.8 +/- 0.7 L/min (p less than 0.05) during atrial pacing at 400 msec cycle length. Propafenone had no effect on pulmonary and aortic diastolic pressures. Lidocaine (5 mg/kg intravenously) caused a significant (p less than 0.05) decrease in aortic systolic pressure and a rise in heart rate. Lidocaine had no significant effect on the other measured hemodynamic parameters. Propafenone, unlike lidocaine, significantly (p less than 0.05) increased atrioventricular nodal functional refractory period and right ventricular endocardial (apex) cathodal (0.5 +/- 0.1 mA to 1.9 +/- 0.3 mA) and bipolar (1.4 +/- 0.3 to 2.2 +/- 0.4 mA) diastolic excitability threshold. Propafenone, unlike lidocaine, also caused a significant (p = 0.05) intraatrial conduction delay; however, neither drug caused conduction slowing in the His-Purkinje system. Both drugs had no effect on sinus nodal recovery time and on the effective refractory period of the right ventricular endocardium (apex). Mean plasma propafenone levels during hemodynamic and electrophysiologic measurement ranged between 3.2 +/- 1.8 micrograms/ml and 1.7 +/- 1.1 micrograms/ml. All of the propafenone-induced effects were reversible within 90 minutes. We conclude that propafenone differs from lidocaine in its atrial, AV nodal, and ventricular electrophysiologic properties, and thus these may explain propafenone's greater efficacy over lidocaine against both certain atrial and ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1984

Assessment of right ventricular function using two-dimensional echocardiography.

With the use of two-dimensional echocardiography (2DE), we analyzed apical and subcostal four-chamber views for evaluation of right ventricular (RV) function in 30 individuals as compared to RV ejection fraction (RVEF) obtained by radionuclide angiography. In addition to previously reported parameters of changes in areas and chords, a new simple measurement of tricuspid annular excursion was correlated with RVEF. A close correlation was noted between tricuspid annular plane systolic excursion (TAPSE) and RVEF (r = 0.92). The RV end-diastolic area (RVEDA) and percentage of systolic change in area in the apical four-chamber view also showed close correlation with RVEF (r = -0.76 and 0.81); however, the entire RV endocardium could only be traced in about half of our patients. The end-diastolic transverse chord length and the percentage of systolic change in chord length in the apical view showed a poor correlation with RVEF. The correlation between RVEF and both areas and chords measured in the subcostal view was poor. It is concluded that the measurement of TAPSE offers a simple echocardiographic parameter which reflects RVEF. This measurement is not dependent on either geometric assumptions or traceable endocardial edges. When the endocardial outlines could be traced, the apical four-chamber view was superior to the subcostal view in assessment of RV function.

Adult↗
PubMed1985

Cardiovascular manifestations of systemic lupus erythematosus.

SLE affects most aspects of cardiac function, and recent studies have reported increasing cardiovascular morbidity and mortality. Pathologically, SLE is characterized by a pancarditis involving pericardium, myocardium, endocardium, and coronary arteries. In autopsy series, pericarditis has been found in 43% to 100% (mean 62%, Table I), and myocarditis was found in 8% to 78% (mean 40%, Table II), but both have been underdiagnosed clinically. Libman-Sacks lesions have been noted in 25% to 100% (mean 43%) and infective endocarditis in 1.1% to 4.9% of clinical and autopsy studies (Table III). Coronary disease may be due to arteritis, which should be treated with high-dose steroids, or it may be due to atherosclerosis, which is amenable to medical or surgical therapy. Valvular disease has been treated surgically, but with a combined surgical mortality as high as 25%. Aortic insufficiency and mitral regurgitation are the most common valvular problems, although aortic and mitral stenosis have also been reported. Hypertension has been noted in 14% to 69%, and heart failure in 5% to 44%. Evidence for a lupus cardiomyopathy, which may be subclinical, is reviewed. While steroids may ameliorate SLE pancarditis, they have also been associated with hypertension, LV hypertrophy, purulent and constrictive pericarditis, mitral regurgitation, and perhaps accelerated atherosclerosis. It remains to be seen if improved diagnosis and treatment of the cardiovascular manifestations of SLE can enhance survival.

Cardiomyopathies↗