Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ENDOCARDIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed2003

Automated cardiac MR image segmentation: theory and measurement evaluation.

We present a new approach to magnetic resonance image segmentation with a Gradient-Vector-Flow-based snake applied to selective smoothing filtered images. The system also allows automated image segmentation in the presence of grey scale inhomogeneity, as in cardiac Magnetic Resonance imaging. Removal of such inhomogeneities is a difficult task, but we proved that using non-linear anisotropic diffusion filtering, myocardium edges are selectively preserved. The approach allowed medical data to be automatically segmented in order to track not only endocardium, which is usually a less difficult task, but also epicardium in anatomic and perfusion studies with Magnetic Resonance. The method developed proceeds in three distinct phases: (a) an anisotropic diffusion filtering tool is used to reduce grey scale inhomogeneity and to selectively preserve edges; (b) a Gradient-Vector-Flow-based snake is applied on filtered images to allow capturing a snake from a long range and to move into concave boundary regions; and (c) an automatic procedure based on a snake is used to fit both endocardium and epicardium borders in a multiphase, multislice examination. A good agreement (P<0.001) between manual and automatic data analysis, based on the mean difference+/-SD, was assessed in a pool of 907 cardiac function and perfusion images.

Algorithms↗
PubMed1998

Disproportional response between refractory period and blood flow to alpha 1- and beta-adrenoceptor blockade in canine ischemic myocardium.

We investigated the response of refractory periods and blood flow to blockade of alpha 1- and beta-adrenoceptors alone, or in combination on endocardium and epicardium, during myocardial ischemia. Dogs were anesthetized with alpha-chloralose and divided into bunazosin (an alpha 1-blocking agent)-treated (0.1-0.2 mg/kg, i.v., n = 14), propranolol-treated (0.2 mg/kg, i.v., n = 12), and vehicle-control (n = 10) groups. The diagonal branches of the left anterior descending artery were ligated. The refractory period (ERP) and blood flow (RMBF) were determined by an S1-S2 extrastimulus method and a nonradioactive microsphere technique, respectively. The duration of regional electrograms (DRE) was measured in the endocardial and epicardial sites. Bunazosin alone reversed the ischemia-related shortening of ERPs at both the endocardial and epicardial sites, with a greater effect seen epicardially (P < .05). Subsequent administration of propranolol further prolonged ERPs in both sites, although the effect was greater in the epicardial surface (P < .05). Bunazosin reduced RMBF to a greater degree at the endocardial site than at the epicardial site in the ischemic zone (P < .01 and P < .05, respectively), but the magnitude of the reduction in RMBF and the difference in RMBF between sites were similar to the control group (P < .01). Propranolol alone and subsequent administration of bunazosin prolonged the ERP more at the epicardial site (P < .01) than at the endocardial sites in the ischemic zone. Propranolol produced no significant difference in RMBF between both sites. DREs in animals treated with bunazosin and propranolol alone, or in combination, were similar to those in animals treated with vehicle. These results suggest that differences in ERPs between endocardium and epicardium with blockade of alpha 1- and/or beta-adrenoceptor are not due to concomitant alterations in RMBF, but to differences in electrophysiological properties of the endocardial and epicardial cells during the acute phase of myocardial ischemia.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed2004

Novel noncontact catheter system for endocardial electrical and anatomical imaging.

The study objective was to integrate noncontact mapping and intracardiac echocardiography (ICE) in a single catheter system that enables both electrical and anatomical imaging of the endocardium. We developed a catheter system on the basis of a 9-F sheath that carried a coaxial 64-electrode lumen-probe on the outside and a central ICE catheter (9 F, 9 MHz) on the inside. The sheath was placed in the right atrium (RA) of 3 dogs, and in the left ventricle (LV) of 3 other dogs. To construct cardiac anatomy, the ICE catheter was pulled back over several beats inside the sheath starting from the tip and two-dimensional tomographic images were continuously acquired. To recover endocardial electrograms, the probe was advanced over the sheath and single-beat noncontact electrograms were simultaneously recorded. Endocardial contact electrodes were placed at select sites for validation as well as for pacing. Three-dimensional electrical-anatomical images reconstructed during sinus and paced rhythms correctly associated RA and LV activation sequences with underlying endocardial anatomy (overall activation error = 3.4 +/- 3.2 ms; overall spatial error = 8.0 +/- 3.5 mm). Therefore, accurate fusion of electrical imaging with anatomical imaging during catheterization is feasible. Integrating single-beat noncontact mapping with ICE provides detailed, three-dimensional electrical-anatomical images of the endocardium, which may facilitate management of arrhythmias.

Animals↗
PubMed2001

Evidence for increased pyridinoline concentration in fibrotic tissues in diffuse systemic sclerosis.

Systemic sclerosis is a generalized disease characterized mainly by the accumulation of collagen in the skin and internal organs. The aim of our study was to determine the amount of collagen cross-link pyridinoline (Pyd) in a variety of fibrotic tissues (skin, fascia, endocardium, bladder) from an autopsy patient with diffuse systemic sclerosis, and to compare these with normal tissues from the same patient. Mean concentrations of Pyd in the fibrotic skin samples (66 mmol/mol collagen) were more than two-times greater than those in the uninvolved normal samples (27 mmol/mol collagen). The increase of Pyd in the endocardium, fascia, and bladder was also markedly higher (1.41 x, 1.26 x and 2.64 x higher than normal samples). The increased deposition of collagen in systemic sclerosis is accompanied by a significantly increased amount of Pyd in the collagen of fibrotic tissues.

Amino Acids↗
PubMed1995

Early fetal endocardial fibroelastosis and critical aortic stenosis: a case report.

Endocardial fibroelastosis is characterized by an abnormal thickening of the endocardium of one or both ventricles; the disorder may occur with or without other cardiac anomalies. A diagnosis of endocardial fibroelastosis in utero using fetal echocardiography may be made on the basis of increased echodensity of the endocardium and poor contractility of the ventricle. We describe a case of very early diagnosis of fibroelastosis and aortic valve stenosis observed in utero at 14 weeks' gestation by transvaginal echocardiography.

Adult↗
PubMed1998

Structure of chordae tendineae in the left ventricle of the human heart.

The bicuspid (mitral) valve complex of the human heart consists of functional units which include the valve leaflets, chordae tendineae and the papillary muscles. The mechanical properties of these functional units depend to a large extent on the link between the muscle and the valve. This link is usually arranged in a branching network of avascular tendinous chordae composed of collagen and elastic fibres, which transmit contractions of the papillary muscle to the valve leaflets. In order to perform their function efficiently, the chordae have to possess a high degree of elasticity, as well as considerable strength and endurance. Human chordae tendineae originating from the left ventricles were obtained from 7 embalmed cadavers and 6 postmortem subjects of various ages. Samples washed in saline were fixed or postfixed in 9 % formol saline. Observations were made by illuminating the chordae along their axes. The reflected images originating from the superficial collagenous layers of the relaxed chordae showed a striped pattern 11 microm in width. Scanning electron and light microscopy of the chordae confirmed an undulating pattern of collagen fibrils arranged in bundles of planar waves in register and around the entire circumference of the chorda. The dimensions of the waves correlated with those of the striped reflected pattern. The observed undulating arrangement of the collagen fibrils appears to produce an inherent built-in elasticity which is likely to be of considerable advantage for a tissue which is under continuous repetitive stress. The chordae were covered by endocardium composed of a superficial layer of smooth squamous endothelial cells and an underlying dense layer of elastic fibres. It is suggested that the relaxed striped chordae, consisting of undulating collagen fibrils, straighten when the chordae become stretched by papillary muscle contraction, thereby mitigating the peak stress developed during muscle contraction. On relaxation the elastic tissue tends to return the collagen to its wavy configuration. It is also suggested that the regular wavy pattern of collagen seen in young individuals gradually changes with age by elongation of the wave pattern which eventually becomes randomised. In addition, with increasing age, substantial cushions of connective tissue appear below endocardium while the dense collagenous core has a reduced cross-sectional area which may lead to stretching and eventual rupture of the chordae.

Adolescent↗
PubMed2004

Transmural distribution of connexins in rodent hearts.

INTRODUCTION: Electrophysiologic heterogeneity across the ventricular wall is a result of differential transmural expression of various ion channel proteins that underlie the different action potential waveforms observed in epicardial, midmyocardial, and endocardial regions. Cardiac connexins mediate cell-to-cell communication, are critical for normal impulse propagation, and play a role in electrophysiologic remodeling in disease states. However, little is known about the transmural distribution of cardiac gap junction proteins. METHODS AND RESULTS: Connexin expression in epicardium, midmyocardium, and endocardium was assessed immunohistochemically in mouse and rat hearts. The total connexin protein content within different ventricular regions was measured by immunoblotting. Connexin43 is twice as abundant in midmyocardium and endocardium compared with epicardium in the mouse but not in the rat. Connexin45 is expressed equally across the left ventricular wall. CONCLUSION: Epicardial myocytes express significantly less Cx43 and therefore may be less well coupled than midmyocardial and endocardial myocytes. A transmural gradient of connexin43 expression across the left ventricular free wall likely results in differences in the stoichiometry of connexins expressed in different regions of the heart.

Animals↗
PubMed2000

Power Doppler imaging as a basis for automated endocardial border detection during left ventricular contrast enhancement.

Echocardiographic evaluation of left ventricular (LV) systolic function relies on endocardial visualization, which can be improved when necessary using contrast enhancement. However, there is no method to automatically detect the endocardial boundary from contrast-enhanced images. We hypothesized that this could be achieved using harmonic power Doppler imaging. Twenty-two patients were studied in two protocols: (1) 11 patients with poorly visualized endocardium (> 3 contiguous segments not visualized) and (2) 11 consecutive patients referred for dobutamine stress echocardiography who were studied at rest and at peak dobutamine infusion. Patients were imaged in the apical four-chamber view using harmonic power Doppler mode (HP SONOS 5500) during LV contrast enhancement (Optison or Definity DMP115). Digital images were analyzed using custom software designed to automatically extract the endocardial boundary from power Doppler color overlays. LV cavity area was automatically measured frame-by-frame throughout the cardiac cycle, and fractional area change calculated and compared with those obtained by manually tracing the endocardial boundary in end-systolic and end-diastolic gray scale images. Successful border detection and tracking throughout the cardiac cycle was possible in 9 of 11 patients with poor endocardial definition and in 10 of 11 unselected patients undergoing dobutamine stress testing. Fractional area change obtained from power Doppler images correlated well with manually traced area changes (r = 0.82 and r = 0.97, in protocols 1 and 2, respectively). Harmonic power Doppler imaging with contrast may provide a simple method for semi-automated border detection and thus facilitate the objective evaluation of LV function both at rest and under conditions of stress testing. This methodology may prove to be particularly useful in patients with poorly visualized endocardium.

Contrast Media↗
PubMed2003

Clinical relevancy of the myocardial velocity gradient: limitations of a binary response.

BACKGROUND: Doppler tissue echocardiographic myocardial velocity gradient (MVG) overcomes translational or tethered motion effects. Diagnostic applications rely on MVG numeric value, an instantaneous value calculated at peak endocardial velocity. Our aim was to test the clinical relevancy of MVG for patients with dilated cardiomyopathy (CM) at rest. Efficiency of MVG, as a marker of the underlying mechanism, ischemic or nonischemic, was compared with that of mean velocities averaged over a cycle. METHODS: Peak and mean velocities were measured and MVG calculated during ejection, and early and late diastole, in the endocardium and epicardium on color M-mode Doppler tissue echocardiographic parasternal recordings of the posterior wall, simultaneously imaged with the septum. The population consisted of 34 patients with similar clinical presentation (left ventricular ejection fraction < 40%, left ventricular end-diastolic diameter > 6 cm, and proven ischemic [14] or nonischemic [20] dilated CM) and 16 control subjects. RESULTS: Doppler tissue echocardiography data significantly differed between control subjects and all patients with CM. Between patients, the only significant differences were found at the posterior wall for mean velocities at the epicardium in systole (9 +/- 4 mm/s for ischemic vs 14 +/- 5 mm/s for nonischemic, P =.002), and at both layers in early diastole (endocardium, 14 +/- 9 vs 29 +/- 12 mm/s, P =.0004; epicardium, 12 +/- 4 vs 22 +/- 11 mm/s, P =.002; ischemic vs nonischemic CM, respectively). CONCLUSION: Specific features of CM were characterized by myocardial velocity changes studied layer by layer throughout a phase. The binary response of transient peak MVG could not reach this goal.

Aged↗
PubMed2000

Atrial endocardial changes in mitral valve disease: a scanning electron microscopy study.

BACKGROUND: The precise contribution of left atrial appendage (LAA) endocardial damage and dysfunction to the process of thrombus formation in patients with mitral valve (MV) disease, especially in the presence of atrial fibrillation (AF), has not as yet been clearly described. This may be important because the LAA is the usual site for thrombus formation. METHODS: The purpose of this study was to describe endocardial surface changes, through the use of scanning electron microscopy, in the left and right atrial appendages of patients with MV disease and the differences, if any, between patients with mitral stenosis and mitral regurgitation as well as between those with AF and sinus rhythm. Our second objective was to relate endocardial changes to plasma levels of von Willebrand factor (vWf), an established marker for endothelial damage. LAA specimens were obtained immediately after commencement of cardiopulmonary bypass from 35 patients (18 men; mean age 65 years, range 20 to 85) during surgery for MV repair or replacement. Right atrial appendage (RAA) specimens were similarly obtained as controls for individual patients. The specimens were fixed in 2.5% glutaraldehyde solution overnight, stored in Sorensen's phosphate buffer, and examined by means of scanning electron microscopy. Two independent observers documented the most advanced lesion in each specimen as follows: (1) "minimal" changes, with minimal disruption of the endocardium; (2) "intermediate" changes or prethrombotic lesions; and (3) "advanced" changes, with endocardial disruption and thrombotic lesions. Plasma levels of vWf were also measured (enzyme-linked immunosorbent assay) in all patients, and results were compared with those of age- and sex-matched healthy control patients. RESULTS: Advanced changes were more frequently seen in the endocardium of the LAA when compared with the RAA (31% vs 6%), whereas minimal changes were more frequently seen in the RAA compared with the LAA (23% vs 6%) (P =.00167). Similarly, the LAA from patients with mitral stenosis had a higher proportion of "advanced" endocardial changes when compared with patients with mitral regurgitation (67% vs 24%; P =.0066). The LAA in patients with AF had more "advanced" changes (39% vs 27%), but this was not statistically significant. Plasma vWf levels were significantly higher in patients with MV disease compared with healthy control patients (132 +/- 33 IU/dL vs 99 +/- 37 IU/dL; P =.0004) and in patients with advanced LAA changes compared with earlier changes (149 +/- 34 IU/dL vs 121 +/- 31 IU/dL; P =.042). CONCLUSIONS: Endocardial damage occurs in the atrial appendages of patients with MV disease. Potentially thrombogenic changes are more commonly seen in the LAA compared with the RAA and in patients with mitral stenosis compared with mitral regurgitation. These anatomic appearances may contribute to the risk of intra-atrial thrombus formation in patients with mitral valve disease, especially if AF is present.

Adult↗
PubMed1995

Myocardial temperatures during in vivo endocardial Nd:YAG laser irradiation.

To determine safety and efficacy of neodymium:YAG laser irradiation of the endocardium, temperatures at both the epicardium and the endocardium were recorded for thermal damage evaluation. A total of 48 coagulation lesions were created at power settings of 20 and 30 W in 20 open chest dogs by transcatheter endocardial laser irradiation. Tissue temperatures were monitored by epicardial thermography (Tepi), and by endocardial thermocouples at the catheter tip (Tprox) and 4 mm below the endocardial surface (Tdist). In group I the optical fiber extended 1 mm from the catheter and irradiation times ranged from 3 to 60 sec. Tepi reached > or = 57 degrees after a weighted average of 5 sec of laser irradiation (n = 44). In group II the fiber was retracted 1 mm from the catheter tip, and irradiation times were 100 to 150 sec. Tepi reached > or = 57 degrees C after a weighted average of 30 sec (n = 4). Blood vessels were recognized as heat sinks until coagulation occurred. Lesion volume showed a proportional increase with total delivered energy. From the observed timeframes in epicardial temperature rise it is suggested that total direct light absorption at the epicardium was the main contribution to Tepi, and the Nd:YAG laser can efficiently create transmural lesions. The epicardial temperatures remained below 80 degrees C in combination with the constant movement of the epicardial wall suggested safety from thermal damage to the ambient organs.

Animals↗
PubMed2003

Effects of halothane on action potential configuration in sub-endocardial and sub-epicardial myocytes from normotensive and hypertensive rat left ventricle.

BACKGROUND: Halothane shortens ventricular action potential duration (APD), as a consequence of its inhibitory effects on a variety of membrane currents, an effect that is greater in sub-endocardial than sub-epicardial myocytes. In hypertrophied ventricle, APD is prolonged as a consequence of electrical remodelling. In this study, we compared the effects of halothane on transmural APD in myocytes from normal and hypertrophied ventricle. METHODS: Myocytes were isolated from the sub-endocardium and sub-epicardium of the left ventricle of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Action potentials were recorded before, during, and after a 1-min exposure to 0.6 mM halothane and APD measured from the peak of the action potential to repolarization at -50 mV (APD(-50 mV)). Data are presented as mean (SEM). RESULTS: In WKY myocytes, halothane reduced APD(-50 mV) from 21 (2) to 18 (2) ms (P<0.001, n=15) in sub-epicardial myocytes but abbreviated APD(-50 mV) to a greater extent in sub-endocardial myocytes (37 (4) to 28 (3) ms; P<0.001, n=14). In SHR myocytes, APD(-50 mV) values were prolonged compared with WKY and APD(-50 mV) was reduced by halothane from 36 (6) to 27 (4) ms (P<0.016) and from 77 (10) to 38 (4) ms (P<0.001) in sub-epicardial and sub-endocardial myocytes, respectively. CONCLUSIONS: In the SHR, hypertrophic remodelling was not homogeneous; APD(-50 mV) was prolonged to a greater extent in sub-endocardial than sub-epicardial cells. Halothane reduced APD to a greater extent in sub-endocardium than sub-epicardium in both WKY and SHR but this effect was larger proportionately in SHR myocytes. The transmural gradient of repolarization was reduced in WKY and effectively abolished in SHR by halothane, which might disturb normal ventricular repolarization.

Action Potentials↗
PubMed1990

Sulphinpyrazone reduces endocardial injury and mural thrombosis.

STUDY OBJECTIVE: The aim of the study was to investigate the effectiveness of sulphinpyrazone, a drug which stabilises endothelial cell membranes, in reducing endocardial injury and mural thrombosis produced by lactic acid in the left ventricle. DESIGN: The left ventricular endocardium of isolated beating rat hearts, perfused via the aorta with oxygenated Krebs-Henseleit buffer, was exposed for up to 4 h to additional lactic acid (pH 6.4), with and without sulphinpyrazone (100 ng x ml-1). After flushing with buffer, passage of 10 ml blood, and further flushing, the hearts were fixed by coronary perfusion and the endocardium examined by scanning electron microscopy. EXPERIMENTAL MATERIAL: Hearts from 48 male albino Wistar rats, weight 270-380 g, were used. MAIN RESULTS: Morphometric analysis of the surface of the papillary muscles showed that lactic acid caused membrane injury in endothelial cells, up to 30% of which exfoliated. However when sulphinpyrazone was present, endothelial cell damage was reduced and there was up to 75% reduction in the area of exposed basal lamina or connective tissue. This was associated with a corresponding reduction in the extent of platelet adhesion (79%) and thrombus formation (94%). CONCLUSIONS: The results show that sulphinpyrazone has the potential to reduce the risk of mural thrombosis following endocardial injury.

Animals↗
PubMed1993

Heterogeneity of action potential waveforms and potassium currents in rat ventricle.

OBJECTIVE: The ionic mechanisms for differences in action potential waveforms in rat left ventricle were studied by recording L-type Ca2+ current, transient outward K+ current, and inwardly rectifying background K+ current in single myocytes. METHODS: Single cells were obtained from adult rat hearts by enzymatic dispersion of tissue segments from the epicardium at the apex and the endocardium at the base of the left ventricle. Whole cell voltage clamp methods together with cell shortening measurements were used to identify the K+ currents involved in early and late repolarisation and to correlate changes in action potential shape with inotropic responses. 4-Aminopyridine was used to block the transient outward K+ current, I(t), to evaluate the contribution of this current to repolarisation. RESULTS: Action potential recordings demonstrated that cells from endocardial tissue at the base of the left ventricle have a considerably longer action potential than those from epicardial tissue at the apex. 4-Aminopyridine had a much more pronounced action potential lengthening and inotropic effects on cells from epicardium than on myocytes from endocardium suggesting that I(t) is larger in the epicardium. Voltage clamp measurements confirmed this. In contrast, the L-type Ca2+ current, the resting membrane potential, and the inwardly rectifying background K+ current were very similar in these two regions of left ventricle. CONCLUSIONS: One significant factor contributing to the heterogeneity of action potential waveforms in rat left ventricle is a differential distribution of a Ca+ independent transient outward K+ current, I(t). Regional differences in action potential duration have important implications for the gradient of repolarisation in rat left ventricle, for the genesis of the T wave of the electrocardiogram, and for both electrical and mechanical restitution (refractoriness).

4-Aminopyridine↗
PubMed1993

The majority of nitric oxide synthase in pig heart is vascular and not neural.

OBJECTIVE: As a physiological mediator of smooth muscle relaxation and possibly a non-adrenergic non-cholinergic (NANC) neurotransmitter, nitric oxide plays a role in regulating coronary artery blood flow and modulating myocardial contractility. Although recent attention has been directed toward neural tissue, we investigated the possibility that vessels, as well as nerves, may be a source of nitric oxide in the heart. METHODS: The NADPH-diaphorase method was used to localise the synthesis enzyme, nitric oxide synthase (NOS), in the pig heart. RESULTS: All regions showed a similar staining pattern. Muscle fibres had virtually no NOS activity. The endocardium showed reaction product in a lattice configuration without much cytoplasmic staining, suggesting that endothelial cell membranes are the primary site of NOS activity. Every vessel contained reaction product in intima but none in the media or adventitia. Muscular arteries had more NOS activity than veins. Lighter staining capillaries coursed along each muscle fibre. Only a few scattered nerve processes and rare neuronal cell bodies with NOS activity were present in the heart; there was no particular spatial relationship between neural tissue and vessels. CONCLUSIONS: (1) the majority of NOS activity in the pig heart is in vascular endothelium, consistent with the concept of nitric oxide as a regulator of coronary blood flow; less is present in the endocardium; (2) paucity of nerves with NOS activity probably indicates that this particular type of NANC neural tissue does not affect coronary blood flow directly; and (3) although muscle fibres have no discernible NOS activity, the rich vascular supply in close proximity may subserve some myocardial function of nitric oxide.

Amino Acid Oxidoreductases↗
PubMed1975

Myocardial distribution of coronary blood flow in the isolated supported heart preparation.

The regional distribution of myocardial blood flow was studied by use of radioactive microspheres (15 micro-meters [mum]) under control conditions and during an intracoronary infusion of norepinephrine (2mug/min). In control experiments endocardial blood flow was generally greater than epicardial flow; during administration of norepinephrine the endocardium received significantly less blood flow. It is proposed that normally the endocardium is well perfused, but under conditions of stress, eg, norepinephrine infusion in the presence of a constant coronary blood flow, decreased endocardial blood flow results.

Animals↗
PubMed2005

Histopathology of intraoperatively induced linear radiofrequency ablation lesions in patients with chronic atrial fibrillation.

AIMS: Radiofrequency (RF) energy has been extensively used in ablation of arrhythmia but so far no analysis of morphological effects in human left atria has been conducted. METHODS AND RESULTS: We studied 59 ablation lesions from seven patients who died 2 to 22 days after open heart surgery plus intraoperative cooled-tip RF ablation to treat permanent atrial fibrillation (AF) (mean 4, 1-11 years). The ablation area was studied by macroscopy and histological analysis. RF ablation produced clearly delineated coagulation necrosis (up to a depth of 5.5 mm) bordered by an irregular zone of incomplete necrosis and fresh bleeding even 22 days post-operatively. No superficial charring, thrombotic deposition, or perforation was documented. Endocardium and subendocardium displayed oedematic loosening and microfragmentation of connective tissue fibres. Early after ablation (2-6 days), interfibrillar disseminated bleeding and necrosis without tissue removal response were found. Later after ablation (21, 22 days), mild inflammatory reaction and granulation tissue appeared. Twenty-five per cent of all studied lesions, especially in the thick region in between left pulmonary veins and mitral annulus (left atrial isthmus) (86%), were non-transmural. Nerve fibres with different degrees of thermal injury were detected in the pulmonary vein ostial region. CONCLUSION: Intraoperative cooled-tip ablation in AF resulted in coagulation necrosis of endocardium, subendocardium, and the atrial myocardial layer to a depth of 5.5 mm bordered by an irregular zone of incomplete thermal damage. Transmurality of the lesions could only be found in 75% of intraoperatively applied lesions.

Aged↗
PubMed1991

Automated identification of left ventricular borders from spin-echo magnetic resonance images. Experimental and clinical feasibility studies.

Gated cardiac magnetic resonance imaging (MRI) permits detailed evaluation of cardiac anatomy, including the calculation of left ventricular volume and mass. Current methods of deriving this information, however, require manual tracing of boundaries in several images; such manual methods are tedious, time consuming, and subjective. The purpose of this study is to apply a new computerized method to automatically identify endocardial and epicardial borders in MRIs. The authors obtained serial, short-axis, spin-echo MRIs of 13 excised animal hearts. Also obtained were selected short-axis, spin-echo ventricular images of 11 normal human volunteers. A method of automated edge detection based on graph-searching principles was applied to the ex vivo and in vivo images. Endocardial and epicardial areas were used to compute left ventricular mass and were compared with the anatomic left ventricular mass for the images of excised hearts. The endocardial and epicardial areas calculated from computer-derived borders were compared with areas from observer tracing. There was very close correspondence between computer-derived and observer tracings for excised hearts (r = 0.97 for endocardium, r = 0.99 for epicardium) and in vivo scans (r = 0.92 for endocardium, r = 0.90 for epicardium). There also was a close correspondence between computer-generated and actual left ventricular mass in the excised hearts (r = 0.99). These data suggest the feasibility of automated edge detection in MRIs. Although further validation is needed, this method may prove useful in clinical MRI.

Animals↗