Posterior Free Wall Research Articles

Primary Left Cardiac Angiosarcoma with Mitral Valve Involvement Accompanying Coronary Artery Disease.

We report here on a 43-year-old female patient presenting with non-ST elevation myocardial infarction, severe mitral regurgitation, and mild mitral stenosis secondary to encroachment of the related structures by a primary cardiac angiosarcoma. A coronary angiography revealed significant stenosis in the left main and left circumflex arteries and at exploration, the tumour was arising from posterior left atrial free wall, invading the posterior mitral leaflet, and extending into all of the pulmonary veins and pericardium. Therefore, no further intervention was performed, except for left internal mammarian artery to left anterior descending artery anastomosis and biopsy. As far as we know, this case is unique with respect to its presentation.

Optimization of novel spectral estimator for fractionated electrogram analysis is helpful to discern atrial fibrillation type

IntroductionParoxysmal versus persistent atrial fibrillation (AF) can be distinguished based on differences in the spectral parameters of fractionated atrial electrograms. Maximization of these differences would improve characterization of the arrhythmogenic substrate. A novel spectral estimator (NSE) has been shown previously to provide greater distinction in AF spectral parameters as compared with the Fourier transform estimator. Herein, it is described how the differences in NSE spectral parameters can be further improved. MethodIn 10 persistent and 9 paroxysmal AF patients undergoing electrophysiologic study, fractionated electrograms were acquired from the distal bipolar ablation electrode. A total of 204 electrograms were recorded from the pulmonary vein (PV) antra and from the anterior and posterior left atrial free wall. The following spectral parameters were measured: the dominant frequency (DF), which reflects local activation rate, the DF amplitude (DA), and the mean spectral profile (MP), which represents background electrical activity. To optimize differences in parameters between paroxysmal versus persistent AF patients, the NSE was varied by selectively removing subharmonics, using a threshold. The threshold was altered in steps to determine the optimal subharmonics removal. ResultsAt the optimal threshold level, mean differences in persistent versus paroxysmal AF spectral parameters were: ΔDA=+0.371mV, ΔDF=+0.737Hz, and ΔMP=−0.096mV. When subharmonics were not removed, the differences were substantially less: ΔDA=+0.301mV, ΔDF=+0.699Hz, and ΔMP=−0.063mV. ConclusionsNSE optimization produces greater spectral parameter difference between persistent versus paroxysmal AF data. Quantifying spectral parameter differences can be assistive in characterizing the arrhythmogenic substrate.

Assessment of cardiac functions in infants with cow's milk allergy.

BackgroundCow’s milk allergy is the most common food allergy in children, with rates estimated at 1.9% to 4.9%. Clinical phenotypes of cow’s milk allergy are varied and involve 1 or more target organs, with the main targets being the skin, respiratory system, and gastrointestinal tract. To date, no studies have investigated detailed cardiac function in children with cow’s milk allergy. The current study aimed to investigate cardiac function in infants with cow’s milk allergy.Material/MethodsWe studied 42 infants with cow’s milk allergy and 30 age- and sex-matched healthy subjects. Cardiac functions were evaluated by M-mode, pulsed-wave, and tissue Doppler echocardiography.ResultsThere were no significant differences in ejection fraction or mitral and tricuspid annular plane systolic excursion between the 2 groups. Pulsed-wave Doppler-derived E/A ratios in mitral and tricuspid valves were similar in both groups. Ea/Aa ratios in the left ventricle posterior wall and right ventricle free wall were lower in patients with cow’s milk allergy than in the control group. The E/Ea ratio in the left ventricle, isovolumic relaxation time, deceleration time, and right and left ventricular myocardial performance indices were higher in patients in the study group.ConclusionsOur study identified reduced early diastolic tissue Doppler velocities in infants with cow’s milk allergy.

The dominant morphology of fractionated atrial electrograms has greater temporal stability in persistent as compared with paroxysmal atrial fibrillation

BackgroundMeasurements of both the dominant frequency (DF) and the time series morphology of complex fractionated atrial electrograms (CFAE) are useful to distinguish persistent from paroxysmal atrial fibrillation (AF). In this study, an algorithm was devised to extract morphologic components according to frequency, and its usefulness for distinguishing CFAE was shown. MethodCFAE of length 16s were obtained at two sites each from the four pulmonary vein ostia (PV), and from anterior and posterior left atrial free wall (FW), in nine paroxysmal and 10 longstanding persistent AF patients. The DF was computed for each of two 8s CFAE segments in each 16s recording. Each CFAE segment was then transformed into a set of basis vectors, which represent electrogram morphology at each frequency. The dominant morphology (DM) is defined as the ensemble average of sequential signal segments, with the segment length equal to the period at the DF. The DMs of the two 8s pairs were correlated. Normalized correlation coefficients were tabulated for all data, and separately for PV and FW. The means and coefficients of variation of the DM correlation coefficients were then plotted, and a linear discriminant function was used to classify persistent versus paroxysmal AF data. For comparison with DM results, CFE-mean and interval confidence level (ICL) were also calculated for persistent versus paroxysmal AF data. ResultsMean correlation of the DM, 1st 8s versus 2nd 8s data, was 0.62+0.22 for persistent versus 0.50+0.19 for paroxysmal CFAE for all recording sites (p<0.001). At single anatomical locations, correlation was greater in persistents than paroxysmals at all sites, but achieved significance only at the left superior (p<0.001) and right superior (p<0.05) PV. Spatial variation in correlation coefficient was greater in paroxysmal than persistent AF (not significant). Using the means of DF correlation coefficients, 17/19 patients were classified correctly. The CFE-mean parameter averaged 89.01±20.99ms in persistents versus 93.96±33.81ms in paroxysmals (p<0.05), while ICL averaged 94.54±18.52 deflections/8s for persistents versus 90.70±19.28 deflections/8s for paroxysmals (p<0.05). ConclusionsIn CFAE recordings, the DM parameter was found to have greater temporal morphologic variation in paroxysmal as compared with persistent AF data (p<0.001). In contrast, only moderate significance between paroxysmal versus persistent AF data was found when using the of CFE-mean and ICL parameters (p<0.05). The DM parameter may thus be useful as a new measure to discern both temporal and spatial variations in CFAE in paroxysmal versus persistent AF recordings.

Early and late results of entire septal patch technique for post infarction ventricular septal rupture

Surgical results for post-infarction ventricular septal rupture (VSR) remain poor, even today. The aim of this study was the establishment and clinical evaluation of a simple, standardized septal patch technique for this disease. From 1999 to 2011, 16 consecutive patients with a mean age of 73.1±10.1 (range 55-89) underwent emergency repair of VSR following anterior myocardial infarction. Entire septal patch technique, in which a large pericardial patch is fixed reciprocally between transmural sutures placed in the posterior free wall adjacent to the ventricular septum and anterior left ventriculotomy closing sutures, thus almost entirely covering the septal wall, was used in all cases. Mean interval between the onset of septal rupture and surgery was 1.3±0.6(range 1-3)days. Eight patients presented cardiogenic shock and 14 patients underwent preoperative intra-aortic balloon pumping. Average operation, cardiopulmonary bypass, and aortic clamp time were 233±71(145-360), 128±51(82-240), and 46±15(29-76)min, respectively. Coronary artery bypass grafting was performed concomitantly in five cases. Average intra-operative blood loss was 340±184(123-740)g. Thirty-day mortality was 0%, and in-hospital mortality was 13.3% (2/16). Significant residual shunt occurred in one patient. All hospital survivors were followed up with a mean period of 44.5±40(5-131)months. Five-year survival of all operated patients was 69±14%. Entire septal patch technique proved to be an easily reproducible method for anterior VSR that demonstrated stable early and late results.

Prevalence and Clinical Profile of Myocardial Crypts in Hypertrophic Cardiomyopathy

In hypertrophic cardiomyopathy (HCM), cardiovascular MR can detect morphological abnormalities of the left ventricle (LV) not visualized with echocardiography. Although myocardial crypts (ie, narrow, blood-filled invaginations within the LV wall) have been recognized in HCM, all clinical implications of these structural abnormalities within the broad clinical HCM spectrum are not completely resolved. Therefore, we sought to characterize the prevalence and diagnostic significance of myocardial crypts in HCM patients. Cine and late gadolinium enhancement cardiovascular MR and 2-dimensional echocardiography were obtained in 292 consecutive patients with HCM including 31 genotype-positive/phenotype-negative family members without LV hypertrophy (28 ± 16 years; 51% male) and 261 patients with LV hypertrophy (46 ± 18 years; 60% male). Ninety-eight subjects without cardiovascular disease were controls. Myocardial crypts (1-6/patient) were identified only by cardiovascular MR in 19 of 31 genotype-positive/phenotype-negative patients (61%) compared with only 10 of 261 (4%) patients with HCM with LV hypertrophy (P<0.001) and were absent in control subjects. Twelve-lead electrocardiograms were normal in 10 (53%) of the genotype-positive/phenotype-negative patients with crypts. Crypts were confined to the basal LV, most commonly in the ventricular septum (n=21) or posterior LV free wall (n=4), and associated with normal LV contractility and absence of late gadolinium enhancement in all but one patient. LV myocardial crypts represent a distinctive morphological expression of HCM, occurring with different frequency in HCM patients with or without LV hypertrophy. Crypts are a novel cardiovascular MR imaging marker, which may identify individual HCM family members who should also be considered for diagnostic genetic testing. These data support an expanded role for cardiovascular MR in early evaluation of HCM families.

Tissue Doppler indexes of left ventricular systolic function in relation to the pulsatile and steady components of blood pressure in a general population

To our knowledge, no population study described the association of the radial and longitudinal components of left ventricular strain with blood pressure (BP) components in continuous analyses. We therefore investigated these associations in participants randomly recruited from the general population in the framework of the family-based European Project on Genes in Hypertension. In 334 participants (55.4% women; mean age, 43.6 year), using tissue Doppler imaging (TDI), we measured the end-systolic longitudinal strain (mean 20.9%) and peak systolic strain rate (1.29 s) from the basal portion of the left ventricular inferior and posterior free walls and radial stain (51.1%) and strain rate (3.40 s) of the left ventricular posterior wall. Models included in addition to covariables and confounders both SBP and DBP or both pulse pressure (PP) and mean arterial pressure (MAP). Effect sizes were expressed per 1-SD increase in BP. Longitudinal strain (-0.62%; P = 0.04 and -0.64%; P = 0.007), but not strain rate, decreased with DBP and MAP. Radial strain (4.0 and -3.4%; P ≤ 0.001) and strain rate (0.38 and -0.18 s; P ≤ 0.04) independently increased with SBP and decreased with DBP. Accordingly, radial strain (2.9%; P < 0.0001) and strain rate (0.22 s; P = 0.0005) increased with higher PP, but were not related to MAP. In the general population, BP is an independent determinant of left ventricular systolic function as measured by TDI. Radial function increased with PP, the pulsatile BP component, whereas longitudinal function decreased with the steady component of BP as expressed by MAP or DBP.

Changes in left atrioventricular valve geometry after surgical repair of complete atrioventricular canal

The most common reason for late surgical reintervention after repair of complete atrioventricular canal defects is the development of left atrioventricular valve regurgitation. We sought to determine the changes in left atrioventricular valve geometry after surgical repair that may predispose to regurgitation. Atrioventricular valve measurements were obtained by 2-dimensional echocardiography at 3 different time points (preoperative, early postoperative, and midterm postoperative [6-12 months]). Left atrioventricular valve annulus area and left ventricular volume were calculated; vena contracta of the regurgitant jet orifice was measured. All measurements were normalized relative to an appropriate power of body surface area. From January 2000 to January 2008, 101 patients with complete atrioventricular canal repair were included. Left atrioventricular valve annulus was noted to remodel from an elliptical shape to a circular shape after surgery. Left atrioventricular valve annulus area increased early postoperatively (systole: 4.1 ± 0.2 cm(2)/m(2) vs 6.1 ± 0.3 cm(2)/m(2), P < .001; diastole: 7.2 ± 0.4 cm(2)/m(2) vs 10.0 ± 0.5 cm(2)/m(2), P < .001, pre- vs postoperative, respectively). This increase was sustained in the midterm postoperative period (systole: 6.1 ± 0.3 cm(2)/m(2), P = .85, vs diastole: 10.0 ± 0.4 cm(2)/m(2), P = .78, early vs midterm postoperative). Left ventricular volume increased in the early and midterm postoperative periods compared with preoperative (systole: 16.9 ± 1.2 mL/m(2) vs 26.2 ± 1.7 mL/m(2), P < .001; diastole: 35.0 ± 2.4 mL/m(2) vs 52.5 ± 3.2 mL/m(2), P < .001). Complete atrioventricular canal repair leads to left atrioventricular valve annular shape change with increased area and circular shape. The change in left atrioventricular valve annulus shape appeared to be mainly due to increased circumference in the posterior free wall of the annulus. These findings may provide a mechanism for the progression of central regurgitation seen after complete atrioventricular canal repair and a potential solution.

Regional Myocardial Dysfunction following Norwood with Right Ventricle to Pulmonary Artery Conduit in Patients with Hypoplastic Left Heart Syndrome

Improved early survival has led many centers to use the right ventricle-to-pulmonary artery (RVPA) conduit instead of the modified Blalock-Taussig shunt for Norwood palliation of hypoplastic left-heart syndrome. However, there is concern regarding the potential deleterious effects of the required right ventriculotomy for placement of the RVPA conduit on global and regional right ventricular (RV) function. The purpose of this study was to investigate global and regional RV wall motion abnormalities after Norwood palliation with RVPA conduit using Velocity Vector Imaging (VVI). Thirty consecutive patients with hypoplastic left-heart syndrome who underwent stage 2 palliation between January 2007 and December 2009 were identified from the surgical database. VVI was performed on two-dimensional echocardiographic images obtained before second-stage palliation. Peak systolic circumferential and radial velocity, strain, and strain rate were measured from parasternal short-axis and apical four-chamber views. RV ejection fraction was measured using the biplane modified Simpson's rule. Regional RV systolic deformations were compared between different RV segments. VVI measures were also compared with RV systolic function. In a subgroup (n = 14), VVI was repeated on follow-up after stage 2 palliation to evaluate changes in regional and global RV deformation. A total of 30 patients (20 males) were studied. The median age at the time of interstage echocardiography was 12 weeks (range, 8-18 weeks). In the short axis, average peak systolic circumferential strain values for the anterior, posterior, septal, and RV free wall segments were 3.79 ± 2.52%, 11.4 ± 5.2%, 13.3 ± 6.5%, and 11.1 ± 5.0%, respectively. From the short-axis view, the anterior RV segment (ventriculotomy site) exhibited significantly reduced circumferential velocity, peak systolic strain, and strain rate (P < .0001). Mean global VVI measurements were correlated with RV ejection fraction. On follow-up after stage 2 palliation, the ventriculotomy region showed persistently reduced velocity, peak systolic strain, and strain rate compared with all other segments. In patients with hypoplastic left-heart syndrome after Norwood palliation with RVPA conduit, RV myocardial deformation was significantly reduced at the ventriculotomy site, which persisted after stage 2 palliation. VVI-derived measures demonstrating impairment of global systolic myocardial deformation were correlated with RV systolic function. Long-term multicenter studies to evaluate the effects of ventriculotomy scar on single systemic right ventricle are required.

Left Ventricular Apical Lipoma Resected Under the Guidance of a Mediastinoscope

We report a 57-year-old man who was found to have a left ventricular apical mass during a routine check-up. He previously had neither any subjective symptom nor hemodynamic problem. The mass was located deeply in the left ventricular cavity. With exploration using a mediastinoscope, we successfully resected the tumor, which was a yellowish lipoid mass that adhered to the trabeculae near the apex. Histopathologic examination of the tumor was consistent with a lipoma, a very rare benign primary cardiac tumor. The mediastinoscope can be useful for surgical resection of tumors located deeply in the left ventricle.

Pioglitazone improves ventricular diastolic function in patients with diabetes mellitus: A tissue Doppler study

Objective — Pioglitazone treatment in type 2 diabetes mellitus produced significant improvements in glycaemic control, plasma lipids, blood pressure and inflammation. The aim of this study was to investigate the effect of pioglitazone on systolic and diastolic function in diabetic patients.Methods and results — Forty-nine diabetic patients were included in the study.The patients had never received thiazolidinedione therapy before. Clinical and echocardiographic variables were measured. 30 mg pioglitazone were administered. The patients were followed up for six months and all the measurements were re-evaluated for comparison. Body mass index (BMI) significantly increased after treatment. Fasting glucose, HbA1c and systolic blood pressure decreased. Insulin resistance improved and the HOMA-IR index decreased after pioglitazone treatment. Mean aortic diameter, left atrial systolic and diastolic volumes significantly decreased after therapy. Among diastolic function variables mitral E wave, E/A, ejection time and pulmonary vein peak reverse flow velocity (PVA) significantly increased whereas isovolumetric relaxation time (IVRT), isovolumetric contraction time (IVCT), deceleration time, E/E’ and pulmonary vein late systolic flow (PVS2) decreased after pioglitazone therapy. Among tissue Doppler variables early (E) ventricular inflow velocities measured from the tricuspid lateral annulus, the mitral septal and lateral annulus, the anterior, inferior and posterior free wall significantly increased. Late (A) ventricular inflow velocities measured from the anterior, inferior free wall and the mitral septal annulus also increased.Conclusion — Pioglitazone treatment in type 2 diabetes mellitus produced significant improvements in measures of glycaemic control and diastolic ventricular function.

Pioglitazone improves ventricular diastolic function in patients with diabetes mellitus: a tissue Doppler study.

Pioglitazone treatment in type 2 diabetes mellitus produced significant improvements in glycaemic control, plasma lipids, blood pressure and inflammation. The aim of this study was to investigate the effect of pioglitazone on systolic and diastolic function in diabetic patients. Forty-nine diabetic patients were included in the study. The patients had never received thiazolidinedione therapy before. Clinical and echocardiographic variables were measured. 30 mg pioglitazone were administered. The patients were followed up for six months and all the measurements were re-evaluated for comparison. Body mass index (BMI) significantly increased after treatment. Fasting glucose, HbA1c and systolic blood pressure decreased. Insulin resistance improved and the HOMA-IR index decreased after pioglitazone treatment. Mean aortic diameter, left atrial systolic and diastolic volumes significantly decreased after therapy. Among diastolic function variables mitral E wave, E/A, ejection time and pulmonary vein peak reverse flow velocity (PVA) significantly increased whereas isovolumetric relaxation time (IVRT), isovolumetric contraction time (IVCT), deceleration time, E/E' and pulmonary vein late systolic flow (PVS2) decreased after pioglitazone therapy. Among tissue Doppler variables early (E) ventricular inflow velocities measured from the tricuspid lateral annulus, the mitral septal and lateral annulus, the anterior, inferior and posterior free wall significantly increased. Late (A) ventricular inflow velocities measured from the anterior, inferior free wall and the mitral septal annulus also increased. Pioglitazone treatment in type 2 diabetes mellitus produced significant improvements in measures of glycaemic control and diastolic ventricular function.

Different characteristics of complex fractionated atrial electrograms in acute paroxysmal versus long-standing persistent atrial fibrillation

Complex fractionated atrial electrograms (CFAEs) may represent a phenomenon associated with sources of atrial fibrillation (AF) and are being used increasingly as targets of catheter ablation. However, current methods have limited efficacy for characterizing CFAEs important to substrate arrhythmogenicity and do not measure electrogram morphology. The purpose of this study was to develop a methodology for quantifying the degree of morphologic heterogeneity in CFAE deflections, and to determine whether there are differences in this measurement between paroxysmal and persistent AF patients. Two successive bipolar CFAEs of length 8.4 seconds each were acquired during AF from two sites each at the ostia of the four pulmonary veins (PVs) and from the anterior and posterior left atrial free wall in patients with paroxysmal AF (N = 10) and long-standing persistent AF (N = 10). Extrinsic and intrinsic features of electrogram shape were used to characterize fractionation in CFAE sequences. The extrinsic parameters were the amplitude, upslope, downslope, and width of each deflection. The intrinsic parameter was the voltage profile as characterized by the sum of absolute values. These measurements were compared to the mean interval between CFAE deflections, a standard fractionation indicator. The variability of intrinsic/extrinsic morphologic parameters was higher in paroxysmal than persistent AF at the left superior PV (P < or =.003), the posterior left atrial free wall, anterior left atrial free wall, left inferior PV, and right superior PV (P <.05 for most parameters), and the right inferior PV (not significant). Mean CFAE deflection intervals were longer at all locations in paroxysmal AF but were significant only at the left superior PV and posterior left atrial free wall (P <.05). Quantitative morphologic parameters were not well correlated with dominant frequency (r(2) <0.32); thus, our new measures are robust to changes in activation rate. A novel method for quantifying CFAEs, independent of activation rate, has been developed. The method demonstrates greater significance in the difference between CFAE morphology in paroxysmal and long-standing AF compared with mean interval between CFAE deflections. The differences identified suggest that CFAE morphology may evolve as AF persists.

Year-long upregulation of connexin43 in rabbit hearts by heavy ion irradiation

A previous study from our laboratory has shown that a single targeted heavy ion irradiation (THIR; 15 Gy) to rabbit hearts increases connexin43 (Cx43) expression for 2 wk in association with an improvement of conduction, a decrease of the spatial inhomogeneity of repolarization, and a reduction of vulnerability to ventricular arrhythmias after myocardial infarction. This study investigated the time- and dose-dependent effects of THIR (5-15 Gy) on Cx43 expression in normal rabbit hearts (n = 45). Five rabbits without THIR were used as controls. A significant upregulation of Cx43 protein and mRNA in the ventricular myocardium was recognized by immunohistochemistry, Western blotting, and real-time PCR from 2 wk up to 1 yr after a single THIR at 15 Gy. THIR > or =10 Gy caused a significant dose-dependent increase of Cx43 protein and mRNA 2 wk after THIR. Anterior, lateral, and posterior free wall of the left ventricle, interventricular septum, and right ventricular free wall were affected similarly by THIR in terms of Cx43 upregulation. The radiation-induced increase of immunolabeled Cx43 was observed not only at the intercalated disk region but also at the lateral surface of ventricular myocytes. The increase of immunoreactive Cx43 protein was predominant in the membrane fraction insoluble in Triton X-100, that is the Cx43 in the sarcolemma. In vivo examinations of the rabbits 1 yr after THIR (15 Gy) revealed no significant changes in ECGs and echocardiograms (left ventricular dimensions, contractility, and diastolic function), indicating no apparent late radiation injury. A single application of THIR causes upregulation and altered cellular distribution of Cx43 in the ventricles lasting for at least 1 yr. This long-lasting remodeling effect on gap junctions may open the pathway to novel therapy against life threatening ventricular arrhythmias in structural heart disease.

Atrial Fibrillation: Focal or Reentrant or Both?

Ablation for atrial fibrillation (AF) is a genuinely viable and increasingly used option for improving quality of life in patients with symptomatic drug-refractory AF. What is remarkable about the limited success achieved with these procedures is that progress has occurred despite a near complete lack of knowledge about what causes or maintains AF. Focal origins for AF were first demonstrated decades ago1–4 with topical application of acetylcholine to junctional tissues and atrial sites triggering AF. More recently, there has been convincing documentation of rapid tachycardia arising from the pulmonary veins inciting AF, thus supporting the concept of “trigger elimination” contributing to the success of pulmonary vein isolation. However, studies also support the presence of multiple reentrant circuits maintaining and possibly initiating AF.5, 6 The ablation era has taught us7–9 that in persistent and chronic AF, trigger elimination alone is not enough and that substrate modification is probably necessary to decrease the likelihood of reentrant wavelet continuance and thereby increase success rates. Even the most ardent supporter of either hypothesis recognizes the limitations of each. How can a focal source exist in this milieu indefinitely, producing and maintaining chronic AF, and how do multiple reentrant wavelets arise spontaneously? Article see p 384 In this issue of Circulation: Arrhythmia and Electrophysiology , Niu et al10 provide important, interesting, and novel insights into solving this age-old riddle using a previously unexplored angle-autonomic manipulation. Acetylcholine was used to induce AF in 31 canines. In 12 of the animal studies, propafenone was administered. They then ablated the ganglionated plexi (GP). Before ablation, AF could still be induced despite administration of propafenone. After ablation, there was a consistent pattern of electrogram organization and atrial synchronization. In addition, subsequent administration of propafenone resulted in the inability to induce atrial tachyarrhythmia. There are several …

The relationship between mitral papillary muscles positions and characteristics of the QRS complex

Background QRS complex characteristics are considered to be one of the most significant diagnostic and prognostic determinants for assessment of several cardiac conditions. However, there is a large variability of the QRS complex even among “normal” individuals. This study was based on 2 assumptions: (1) that the portion of the left ventricular endocardium activated earliest is directly supplied by the “fanlike” distribution of the anterior, middle, and posterior fascicles of the left bundle branch, and (2) that the anterior and posterior fascicles course toward their respective mitral papillary muscles. These structures could therefore serve as anatomical landmarks to indicate the borders of this fanlike distribution of primary “start points” of left ventricular activation. Aims The primary aim of this study is to test the hypothesis that location of both papillary muscles closer to the septum correlates with longer QRS duration. The secondary aim of the study is to test the hypothesis that the balance of the distances of the anterior and posterior papillary muscles from the septum is related to the direction of the frontal plane QRS axis. Methods The study population consisted of 16 healthy adult volunteers with a mean age of 26 ± 9 years, mean height of 170 ± 12 cm, and mean weight of 68 ± 10 kg. Measurements were done on the magnetic resonance images from all study subjects. Positions of papillary muscles were assessed as a predictive variable of QRS duration. Results A significant correlation was found between the closer position of both papillary muscles to the septum and longer QRS duration ( R = 0.7, P = .02). Subjects with higher ratio of anterior papillary muscle vs posterior papillary muscle free wall angle correlates with inferior rotation of the average axis of QRS complex in the frontal plane ( R = 0.5, P = .04). Conclusions The positions of the papillary muscles in relation to the free wall and septum wall can be predictive of both QRS duration and the direction of the QRS complex of the heart. These results might provide a new basis for prediction of QRS complex characteristics of an individual and, thus, differentiate between real QRS complex abnormalities and variants of normal.

High sensitivity of the sheep pulmonary vein antrum to acetylcholine stimulation

Isolation of the pulmonary vein antrum can terminate atrial fibrillation, but the rationale has not been elucidated. In the present study, we show that sheep atrial effective refractory period (ERP) was heterogeneously shortened by acetylcholine administration. After perfusion with 15 muM acetylcholine, the shortest ERP occurred in the pulmonary vein antrum, which was recorded with the standard intracellular microelectrode technique (the ERP results in the pulmonary vein antrum, left atrial posterior wall, roof, free wall and appendage, and right atrial free wall were 52.0 +/- 1.6, 75.1 +/- 2.0, 77.2 +/- 1.7, 85.6 +/- 1.7, 64.3 +/- 2.1, and 90.5 +/- 1.3 ms, respectively; P < 0.05). Immunofluorescent staining revealed that muscarinic type 2 receptors (M(2)R) were also distributed heterogeneously in the atrial myocardium, with the highest density in the antrum (the relative fluorescent intensity results of the M(2)R in the pulmonary vein antrum, left atrial posterior wall, roof, free wall and appendage, and right atrial free wall were 62.64 +/- 2.56, 53.12 +/- 2.76, 51.83 +/- 2.45, 47.90 +/- 2.33, 55.27 +/- 2.08, and 45.53 +/- 2.02, respectively; P < 0.05), which was in accordance with the heterogeneity of ERP distribution. Thus the pulmonary vein antrum is a unique electrophysiological region with high sensitivity to acetylcholine, and its intensive response to acetylcholine is most likely associated with the dense M(2)R distribution of this region. Such an acetylcholine-induced ERP heterogeneity is possibly a substrate for atrial fibrillation and hence one of the potential electrophysiological bases for the isolation therapy.

Atrial Tachycardia With Widely-Split P Waves may Mimic a Distinct Faster Atrial Tachycardia With Half the Cycle Length of the Actual P-P Interval

A 57-year-old man with atrial tachycardia (AT) after cavo-tricuspid isthmus ablation underwent electrophysiological testing. Mapping revealed atrial activation with a cycle length exactly twice that of the P-P interval on electrocardiogram. Electroanatomic mapping revealed an AT focus near the left superior pulmonary vein, with inter-atrial conduction occurring in the lower septum and cavo-tricuspid isthmus conduction block. A propagation map demonstrated activation going down the left atrial posterior wall and right atrial free wall, generating different positive P waves in the inferior leads. The focal AT with inter- and intra-atrial conduction block exhibited widely-split P waves misinterpreted as a distinct AT.

Dying from cardiac tamponade

BackgroundTo determine the causes of cardiac tamponade (CT), focussing especially on haemopericardium (HP), as a terminal mode of death, within a 430,000 rural English population.MethodsOur hospital mortuary register and, all postmortem reports between 1995 and 2004 inclusive, were interrogated for patients dying of CT or HP. The causes of CT/HP and selected morphological characteristics were then determined.Results14,368 postmortems were performed in this period: of these, 461 patients died of CT. Three cases were due to non-haemorrhagic pericardial effusion. HP accounted for the remaining 458 cases of which, five were post-traumatic, 311 followed rupture of an acute myocardial infarction (RAMI), 138 after intra-pericardial rupture of dissecting ascending aortic aneurysms (RD3A) and four were due to miscellaneous causes.HP was more commonly due to RAMI. Men tended to die from RAMI or RD3A earlier than women. RAMI or RD3A were commoner in men <70 yrs, but more frequent in women after this.Two thirds of RAMI were associated with coronary artery thrombosis. Anterior free wall rupture was commonest overall, and in women, but posterior free wall rupture was commoner in men.The volume of intrapericardial blood in RAMI (mean = 440 ml) and RD3A (mean = 498 ml) varied between 150 and 1000 ml: intrapericardial blood volume was greater in men than in women dying from either RAMI or RD3A.ConclusionAt postmortem, CT is most often related to HP, attributable to either RAMI or intrapericardial RD3A. Post-traumatic and other causes of CT are infrequent.

Regional difference in ischaemia-induced myocardial interstitial noradrenaline and acetylcholine releases

Knowledge of the regional differences in myocardial interstitial noradrenaline (NA) and acetylcholine (ACh) levels during ischaemia would be important to understand the abnormality of neuronal environment surrounding the ischaemic heart. Using a cardiac microdialysis technique, we compared ischaemia-induced changes in the myocardial interstitial NA and ACh levels among three groups of anesthetized cats: the anterior free wall of the left ventricle (ANT group, n = 7; the left anterior descending coronary artery was occluded), the posterior free wall of the left ventricle (POST group, n = 6; the left circumflex coronary artery was occluded), and the right ventricle (RV group, n = 6; the right coronary artery was occluded). The maximum NA level was not different between the ANT and POST groups but was significantly lower in the RV group ( P < 0.01) [70 nM (SD 37), 106 nM (SD 99), and 7 nM (SD 10), respectively]. The maximum ACh level was not different between the ANT and POST groups but was significantly lower in the RV group ( P < 0.05) [16 nM (SD 7), 20 nM (SD 15), and 6 nM (SD 2), respectively]. In contrast, there were no significant differences in NA or ACh release in response to a local administration of ouabain (10 mM) among the ANT, POST, and RV groups ( n = 6 each). In conclusion, the regional difference of the ischaemic effects, rather than the regional difference in the functional distributions of sympathetic and vagal efferent nerve terminals, might contribute to the lower levels of ischaemia-induced NA and ACh releases in the RV group.