Posterior Papillary Muscle Research Articles

Mitral valve prolapse and mitral annulus disjunction: be aware of a potential arrhythmogenic substrate

Mitral valve prolapse is a relatively common disease with a good overall prognosis. However, in specific clinical and instrumental contexts, patients at high risk of ventricular arrhythmias and sudden cardiac death can be identified. Female sex, history of palpitations or syncope, bi-leaflet myxomatous valve, ECG repolarization abnormalities in the inferior leads, complex ventricular arrhythmias, left ventricular fibrosis detected by cardiac magnetic resonance correlate with a higher risk clinical profile. Additionally, morpho-functional abnormalities of the mitral valve annulus, particularly mitral annulus disjunction, may cause a mechanical stretch at the inferior basal ventricular wall and posterior papillary muscles, predisposing to myocardial fibrosis and arrhythmias. A risk stratification strategy is needed to identify patients with mitral valve prolapse and/or mitral annulus disjunction at high risk of arrhythmias; however, few data are available. Further prospective multicenter studies are warranted, focusing on medical therapy, the role of implantable cardioverter-defibrillators for primary prevention, efficacy of targeted catheter ablation or mitral valve surgery.

Cadaveric Study on the Morphology and Morphometry of Heart Papillary Muscles.

IntroductionA normal atrioventricular valve complex of the heart consists of the atrioventricular (A-V) ring, cusps, chordae tendineae, and papillary muscles. The right ventricle contains three while the left ventricle contains only two papillary muscles, which are named according to their location. A thorough understanding of the normal anatomy as well as possible variations can help surgeons in various corrective surgeries involving papillary muscles.Material & methodsThe study included 50 formalin-preserved hearts procured from human cadavers of unknown age and cause of death. The number of papillary muscles along with their shape, size, and pattern were noted separately for each ventricle. Data were analyzed using SPSS Version 21.0 (IBM Corp., Armonk, NY).ResultsThe left and right ventricles contained two and three papillary muscles, respectively, in all the hearts. In the right ventricles, conical shape and the single base and divided apex (SBDA) pattern were found to be most prevalent. Anterior papillary muscles exhibited the mean length of 12.71±3.81 and 16.41±4.33 in the right and left ventricles, respectively. Similarly, posterior papillary muscles exhibited a mean length of 12.40±3.03 and 14.64±3.92 in the right and left ventricles, respectively. Both differences were found to be statistically significantConclusionFor the appropriate functioning of valves, both anatomical and mechanical coherence of the papillary muscles is required. A very keen understanding of this valvular complex is thus essential for anatomists, physiologists, and cardiologists to deal with normal as well as pathological valvular conditions.

Quantification of mitral papillary muscle function using speckle tracking echocardiography in apparently healthy population

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiac mitral papillary muscle is a structure that has been long ignored. Recently, growing evidence from case reports showed an important role in the pathophysiology of many cardiac pathologies such as hypertrophic cardiomyopathy and dilated cardiomyopathy. To our knowledge, there isn’t any approved standard technique nor any methodological descriptive study of papillary muscle function in the apparently healthy population. Purpose To investigate mitral papillary muscle function in apparently healthy population by speckle tracking echocardiography (STE) using a proposed standard method. Methods We prospectively performed standard transthoracic echocardiography(TTE) in an apparently healthy cohort. Posterior mitral papillary muscle(PPM) was visualized on a modified three chamber view. The anterior papillary muscle(APM) was visualized on a modified 4 chamber view. To measure the value of the papillary muscles longitudinal strain, tracing of PPM and APM was done by a drag and click technique using an ECHOPAC software. Good quality tracing was ensured before approving the measurements. Each papillary muscle was divided into three segments by the software. 2D longitudinal strain curves of each papillary muscle consisted in 3 solid lines of the three segments and a dashed line that represented the mean longitudinal strain of the whole papillary muscle. This latter line was used to derive peak values, post systolic shortening (PSS) and systolic stretch (SS). Time of aortic valve closure was determined on the LV outflow pulsed doppler. Results Our study included 57 apparently healthy individuals between May 2021 and August 2021. Two patients were excluded due to lack of echogenicity. 71.19% (n = 44) were male. Mean age was 36 ± 14 yrs. 15.7% (n = 9) had history of hypertension and 7% (n = 4) were diabetic. 3.5% (n = 2) had history of stroke. 91.2% (n= 52) had functional status NYHA class I, 12.2% (n = 7) had functional status class II. All of our cohort had a left ventricular ejection fraction (LVEF) above 55%, did not have diastolic dysfunction and were on sinus rhythm. PPM peak strain value was -15.49 ±4.69 %. PSS was present in 98.2% (n = 56) and SS in 62.5%(n = 36) of cases. Anterior papillary muscle (APM) had a peak strain value of -15.61 ± 3.66, PSS was present in 78.5% (n = 45) and SS in 51.7% (n = 29). Conclusion Mitral papillary muscles echocardiographic study is feasible in routine scans with modified apical views. Post systolic shortening and systolic stretch are present in the majority of individuals. Abstract Figure. posterior papillary muscle strain curve Abstract Figure. anterior papillary muscle strain curve

A Case of Left Ventricular Free Wall Rupture with Suspected Posterior Papillary Muscle Necrosis

A Case of Left Ventricular Free Wall Rupture with Suspected Posterior Papillary Muscle Necrosis

Surgical Management for Systolic Anterior Motion (SAM) of the Mitral Valve in Obstructive Hypertrophic Myopathy.

In patients with obstructive hypertrophic cardiomyopathy, left ventricular outflow tract (LVOT) obstruction can be created by the hypertrophic interventricular septum (IVS) as well as systolic anterior motion (SAM) of the anterior mitral leaflet (AML). Sufficient septal myectomy is a fundamental surgical technique to treat LVOT obstruction, however, direct surgical management for SAM is another key aspect. Besides the hypertrophic IVS, mitral valve, subvalvular apparatus, and papillary muscle may play important role for SAM and several surgical techniques have been proposed to treat SAM in literature. In this review, each surgical technique is classified by the anatomical structure on which the surgical procedure is applied. The AML is the main surgical site and is applied with plication (vertical plication, resection–plication–release strategy), extension (the AML extension, transverse incision of the AML), sutured (edge-to-edge repair, anterior leaflet retention plasty), or traction (floating stitch, papillary muscle-to-anterior annulus stitches, paradoxical stitches, transposition of a directed chorda tendinea to the AML). Height reduction of the posterior mitral valve leaflet and papillary muscle reorientation are other techniques. We should understand theoretical aspects of each technique on correction of anatomical and functional abnormalities of the structure and should apply them under proper indication.

787 Ablation of the ventricular ectopic foci: a therapeutic option for dilated cardiomyopathy due to arrhythmic MVP

Abstract Aims A subset of patients with mitral valve prolapse (MVP) are affected by a still not well understood condition characterized by frequent ventricular arrhythmias (mostly originating from papillary muscles) and sudden cardiac death (SCD). It is called MVP malignant syndrome (MVP MS). In these patients, the high arrhythmic burden may lead to left ventricular (LV) dyssynchrony and dysfunction, determining a tachycardia-induced cardiomyopathy (TIC). Reduction in arrhythmic burden determines LV recovery and ejection fraction improvement and interrupts LV progressive dilatation. Methods and reports We report the case of a 52-year-old woman with MVP and family history of both MVP and SCD who was referred to our department for symptomatic extrasystoles and dyspnoea during exercise. Palpitations begun 11 years before: in that occasion she performed a 3-lead-ECG-Holter monitoring which documented 3457 ventricular extrasystoles. Transthoracic echocardiography (TTE) showed normal LV dimension and function and a myxomatous mitral valve with prolapse of both leaflets. At that time beta-blocker therapy was introduced, but soon suspended because of patient’s clinical intolerance (bradycardia and hypotension). Since then she was lost at follow-up for years, until symptoms worsened. When she came to our attention, TTE showed dilated and hypokinetic LV (ejection fraction was 38%, S2 wave at TDI was 6.4 cm/s and global longitudinal strain value was −13%). CMR was performed and confirmed TTE findings. Mitral-annulus disjunction was described in anterior, lateral, and posterior wall and late gadolinium enhancement analyses showed subendocardial fibrosis in correspondence of the posterior papillary muscle (PM) and in the mid-inferior wall. Holter monitoring enlightened a high arrhythmic burden with 24 065 premature ventricular complexes (PVCs) of two morphologies (right bundle branch block-like and −120° axis and right bundle branch block-like and −75° axis). During stress test, PVCs increased as the heart rate increased, resulting in bigeminism at peak exercise. Considering all these features, we hypothesized a case of MVP MS in which the high ventricular arrhythmic burden resulted in TIC. Any available pharmacological attempt to reduce arrhythmias failed. Transcatheter (TC) ablation of PVCs was then proposed. Electrophysiological study identified the inner part of the posterior papillary muscle implantation region and the antero-lateral basal wall as PVCs sites of origin. Radiofrequency ablation was performed in both sites. After the procedure, despite an incomplete suppression of the posterior PM focus, 12-lead 24-h Holter monitoring and TTE performed during the hospitalization showed a consistent arrhythmic burden reduction and LV function improvement. At 6 months from the procedure, symptoms improved and Holter monitoring showed 7515 PVCs with a 54% arrhythmic burden reduction compared with the presentation. TE showed lower LV end-diastolic volume and an increase in ejection fraction up to 47%; global longitudinal strain was −17% and TDI showed a S2 wave on lateral wall of 11 cm/s, confirming left ventricle improvement after the arrhythmic burden reduction. Conclusions Complete suppression of PMs PVCs with TC ablation is difficult to obtain, especially when the focus is in the inner part of the PM and TC ablation of ventricular arrhythmias in MVP patients has not yet demonstrated his efficacy in reducing SCD. Nevertheless, it should be taken into consideration to obtain at least PVCs reduction in patients with high arrhythmic burden leading to TIC.

384 Morpho-functional analysis of subvalvular apparatus in mitral valve prolapse and response to dipyridamole stress echocardiography. A pilot study

Abstract Aims Myocardial fibrosis has been found in papillary muscles (PM) and basal segment of left ventricular (LV) inferior-lateral wall in patients with mitral valve prolapse (MVP), which may be due to stretch from valve. Moreover, ST-segment depression is common in patients with MVP, despite low prevalence of epicardial coronary artery disease, and it is attributed to microvascular dysfunction or myocardial stretch. Longitudinal strain (LS) correlates with myocardial fibrosis, while dipyridamole stress echocardiography (DSE) identifies microvascular dysfunction. We aimed at assessing morphology and function of PM and left ventricular walls at rest and during DSE by LS, and at determining prevalence of microvascular dysfunction in patients with MVP. Methods and results Seven consecutive patients with MVP (age 55.4 ± 15.7 years, 57% female) and LV ejection fraction 64 ± 5% underwent DSE. Length and LS of PM were measured at rest and retrospectively compared with those of patients with ischaemic heart disease (n = 8, age 67.1 ± 10.1 years, 37% female) and healthy controls (n = 8, age 39.6 ± 13.3 years, 50% female). LS of PM and LV was also determined at rest and during stress in MVP. Length of PM did not differ among groups, but in MVP, posterior PM was longer than the anterior PM (24 ± 3.8 vs. 20.6 ± 3.6 mm, P = 0.028). Significant difference in resting PM LS was found among groups (overall P = 0.04), with PM LS value in MVP (16.7 ± 7.1%) intermediate between ischaemic (14.2 ± 3.2%) and controls (20.5 ± 2.7%). No difference was found between rest and stress LS of PM in MVP. Global LS tended to increase in MVP during DSE compared to rest (23.1 ± 3.8% vs. 21.1 ± 2.6%, respectively, P = 0.07), while no significant difference between rest and stress LS was found in every LV myocardial segments. Nevertheless, in MVP, LS of LV inferior-lateral wall tended to improve under DSE in patients with mild regurgitation (19.7 ± 4.6 vs. 14.2 ± 5 at rest), but to decrease (16 ± 6.1 vs. 20.3 ± 2.3 at rest) in patients with severe mitral regurgitation (P = 0.006 for interaction). ST-segment depression was elicited by DSE in 29% of MVP. No significant difference in echocardiographic parameters was found between patients with and without ST-segment depression. Conclusions In MVP, sub-valvular apparatus may have peculiar morpho-functional features. DSE does not alter LS of PM, neither of LV walls, except for inferior-lateral wall, which impairs in severe mitral regurgitation. Prevalence of microvascular dysfunction is comparable to that of the general population.

Abstract 10221: Premature Ventricular Contractions in Chronic Thromboembolic Pulmonary Hypertension Undergoing Pulmonary Thromboendarterectomy Surgery

Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and progressive subtype of severe pulmonary hypertension. Premature ventricular contractions (PVC) are common and can be a marker of cardiomyopathy. We aimed to describe the incidence, location and predictors of PVCs in CTEPH patients undergoing Pulmonary Thromboendarterectomy surgery (PTE). Hypothesis: PVCs are common in CTEPH patients and the right ventricle would be the most common location of PVCs. Methods: We reviewed the charts of 883 consecutive patients who were referred for PTE. 12-lead ECGs were reviewed for presence of PVC. Demographics, baseline lab and imaging were extracted from chart review. Predictors of PVCs were analyzed using multivariate backward logistic regression. PVC location was identified using standard location algorithms based on the 12-lead ECG. Results: Overall, 6.5% (n=57) of patients had PVCs. Surprisingly, the majority of PVCs originated from the left ventricle (75.4%, N=43). The most common location was non-outflow tracts with LV non-outflow tract (59.3%, N=34), followed by RV non-out tract (19.3%, N=11). Within the non-outflow tract region, the majority of the PVC location appeared to be septal related (moderator band, posterior fascicle or posterior medial papillary muscle). The mitral annulus was also a common location (15.8%, N=9). In a multivariate model, heart failure (OR 2.8, p=<0.01), coronary artery disease (CAD) (OR 2.8, p=<0.01), sleep apnea (OR 2.2, p=0.02) and obesity (OR 1.6, p=<0.01) increased the odds of having PVCs. Conclusions: PVCs are not uncommon in CTEPH patients undergoing PTE surgery. Overall, 6.5% of patients had PVCs with the majority originating in the left ventricle (75.4%). Using standard ECG criteria, the most common location was the LV non-outflow tract. Heart failure, CAD, sleep apnea and obesity increased the odds of having a PVC.

Abstract 13766: The Use of Echocardiography to Assess Regional Strain Abnormalities in Patients With Chronic Mitral Regurgitation

Background: Patients with primary mitral regurgitation (MR) secondary to mitral valve prolapse (MVP) have regional LV fibrosis in myocardial segments adjacent to the posterior papillary muscle detected by MRI not seen in other patients with MR.. Echocardiographically determined strain is associated with LV fibrosis. Patients with chronic MR are generally followed by echocardiography, however no study has utilized echocardiography to examine regional strain variations in these patients. The object of this study was to examine regional myocardial strain in patients with chronic MR with and without MVP. Methods: Patients undergoing routine transthoracic echocardiography for the assessment of chronic severe MR were included. Patients with secondary MR, ejection fraction < 50%, other significant primary valve disease, history of cardiomyopathy, ischemic heart disease, previous cardiac surgery or pacemaker implantation were excluded. The primary MR subjects were be divided into MVP or non-MVP cohorts. MVP was defined as displacement of 1 or both mitral leaflets by at least 2 mm below the mitral annulus in parasternal long-axis view. Global and segmental strain analysis in 17 left ventricular segments was performed offline and results of the MVP and non-MVP groups compared. Results: 28 patients (mean age 63 ±14 yrs ; 23F/5M) of whom 11 had MVP and 17 had non-MVP disease were included in the study. Patients in the MVP group were significantly younger (59.2 ± 16 vs 69 ± 11 p = 0.05) then in the non-MVP group. Standard echocardiographic measurements including ejection fraction were similar except for estimated PA pressure which was lower in the MVP group, (31.3 ± 6.9 vs 42.6 ± 11.9 mmHg p-value = 0.008).Global strain was normal and similar in the two groups (-21.3 ± 4.4% vs -19.9 ± 2.9%; p = 0.30). (Patients with MVP had significantly reduced segmental strain in the inferior basal segment ( -11.2 ± 9.7 in the MVP group, -18 ± 2.6 in the non-MVP group, p-value 0.037). No other segments showed significant differences between the MVP and non-MVP groups Conclusions: Our findings suggest that patients with chronic MR and MVP have significantly reduced echocardiographic strain in the inferior base when compared to patients with MR secondary to other causes.

A cadaveric study on chordae tendinae of human tricuspid valve

Aim of the present study was to observe the types of chordae tendinae present in tricuspid valve of human heart. Morphology of chordae tendinae in tricuspid valve gains utmost importance in cardiac surgeries in recent times because advent in modern technologies in treatment of tricuspid valve diseases.This study was carried out on 96 normal formalin fixed human post-mortem heart specimens. Types of chordae tendinae observed on the basis of their attachments.Chordae tendinae were observed in all specimens. Five types of chordae tendinae were identified namely rough zone, free edge, fan shaped, deep and basal chordae. Anterior papillary muscle was seen providing attachment to 2 to 9; Posterior papillary muscles were seen with 1 to 6 and Septal papillary muscles provided attachment to 1 to 4 chordae tendinae.We hope this study will serve to understand the tricuspid valve complex and types of different chordae tendinae better and it will help in various surgical procedures done on tricuspid valve.

Morphology of the papillary muscles and the chordae tendineae of the ventricles of adult human hearts

IntroductionThe papillary muscles (PM) play a vital role in atrioventricular (AV) valve function. The PM and their chordae tendineae (CT) regulate the closure of the AV valve during systole. The present study was undertaken to categorize the PM based on their shapes and variant patterns and CT based on their types and the branching pattern. MethodsThis study included formalin-fixed ten adult cadaveric heart specimens. We observed the number, shape, length, breadth, pattern, and presence of extra PM. The number of chordae attached to the tip of each PM was quantified. We classified the types and branching patterns of the chordae and their pattern of attachment to the cusps. ResultsIn the right ventricle, conical, truncated, and flat-topped PM were observed. The anterior PM had 5.3 ± 1.9, the posterior PM had 2.7 ± 2.1, and the septal PM had 3.5 ± 2.3 CT attached to it. In the left ventricle, we observed conical, truncated, flat-topped, bifurcate, and trifurcate shapes of PM. The anterior and the posterior PM had 7.7 ± 2.8 and 7.7 ± 2.7 CT attached to them, respectively. The true CT were cusp, cleft, and commissural and the false CT were pillar-wall, inter-pillar, and strut. We also found 3 branching patterns for the chordae (single, fan-shaped, and web forming). ConclusionThe study explored the comparative morphology of PM and chordae in the right and left ventricles. The knowledge of the morphological pattern of PM and CT would contribute to the valvular function and aid in diagnosing conditions such as valve prolapse or regurgitation.

The mitral annulus disjunction as a risk marker in mitral valve prolapse

ResumenLa disyunción del anillo valvular mitral es una anormalidad estructural que consiste en un desplazamiento auricular del punto de articulación de la válvula mitral, lo que lleva a una relación espacial alterada entre la válvula y la pared ventricular posterior adyacente. Los estudios han demostrado una relación entre la disyunción del anillo mitral, las arritmias ventriculares y la degeneración fibrosa miocárdica, lo que incrementa el riesgo de muerte súbita, en especial en mujeres jóvenes. Se presenta el caso de una mujer de 30 años, sin antecedentes relevantes, con palpitaciones frecuentes, en quien se documentó un aumento del automatismo ventricular con incremento progresivo de la carga arrítmica hasta el 20% a pesar del manejo farmacológico. En la resonancia cardiaca se apreció un desplazamiento de 15 mm hacia la aurícula de las valvas de la mitral compatible con disyunción del anillo mitral, además de focos de realce tardío de distribución mesocárdica, no coronariana. Ante los hallazgos y la persistencia de los síntomas, se llevó a estudio electrofisiológico, mapeo 3D y ablación. En la ecografía intracardiaca se apreciaron dos regiones hiperecoicas, en la longitud del músculo papilar anterior y en el mesocardio de la base del músculo papilar posterior; ambos focos relacionados con los sitios morfológicos de interés, en los cuales se aplicó energía de radiofrecuencia. Durante el procedimiento presentó un episodio de fibrilación ventricular que se consideró una extrasistolia ventricular maligna, por lo que se implantó un cardiodesfibrilador para prevención de muerte súbita. Se revisa la literatura y se analizan las relaciones fisiopatológicas existentes entre la disyunción del anillo mitral, los complejos ventriculares prematuros y el riesgo de muerte súbita.

English

BACKGROUND The papillary muscle basal connections have significant clinical implications. Variety of studies done on its morphology and function by various specialists in different departments. A close look on these revealed the interconnections of papillary muscles to one another and to the interventricular septum of both ventricles is related to uncoordinated contractions of papillary muscles, leading to hyper or hypokinesia or prolapse or even its rupture. METHODS Our study done in 25 formalin soaked hearts revealed after the deep and meticulous dissection, reflecting the walls of ventricles laterally the numerous interconnections of papillary muscles at its bases and IVS. Ventricles are opened by inverted ‘L’ shaped incision and its reflected more laterally till all the papillary muscles is visible in one frame after incising the moderator band. The connections were noted, measured, photographed, tabulated, compared with similar studies and analysed with experts with respective fields. RESULTS Almost all the specimens did have the interconnections. Further the post mortem findings of the cardiac related deaths with involvement of papillary muscles suggest damage to such ‘bridges’. The moderator band extensions to the base of right APM, and its extension to the posterior groups is noted in all the specimens. The bridge from the IVS to bases of both the groups of papillary muscles is noted in left ventricle. In90% of specimens the one PPM is found to be loosely connected, more so in left ventricle. CONCLUSIONS We are of a conclusion that such basal interconnections and to the interventricular septum are responsible for rhythmic contractions of papillary muscles of both ventricles. Since the AV valves have to open simultaneously, interconnections becomes mandatory as the impulse has to reach it before it reaches the trabeculae carniae. One of the Posterior papillary muscles is loosely connected to other papillary muscles, may be the reason for its rupture, more so in left ventricle. KEYWORDS Papillary Muscle, Interbasal Connection, Moderator Band, Valvular Prolapse, AV Valves

An unusual case of ischemic mitral valve

Mechanisms leading to mitral regurgitation can be multiple and have different etiologies. We present the case of severe mitral insufficiency due to posterior papillary muscle rupture in a young man, with exertional dyspnea, but permanently asymptomatic for chest pain and without clinical and laboratory signs of myocardial ischemia at the time of our evaluation.

RENOVASCULAR HYPERTENSION-INDUCED CARDIAC CHANGES IN A RAT MODEL: FEASIBILITY OF CONVENTIONAL AND RECENT ECHOCARDIOGRAPHY

Objective: Renovascular hypertension (RH) is a major cause of secondary hypertension, and hypertension eventually led to cardiac remodeling in patients. Hypertension leads to concentric left ventricle hypertrophy, while hypervolemia originated from renal failure leads to eccentric hypertrophy. Both mechanisms occur in RH which results in complex cardiac remodeling. Uraemic cardiomyopathy results from RH is characterized by diastolic dysfunction, but traditional echocardiography was limited in evaluating the diastolic function due to unknown hemodynamic and morphologic status. Recently, non-invasive intraventricular pressure gradient (IVPG), a preload-independent diastolic function parameter, was established and showed higher sensitivity to evaluate diastolic dysfunctions, particularly during cardiomyopathy. However, no previous studies highlighted the feasibility of the IVPG in the diagnosis of RH. Design and method: Twelve rats were received subtotal nephrectomy in 1 week to produce progressive renal failure as the RH group. The other twelve rats were sham-operated as a control group. Conventional and color M-mode echocardiography was performed for isoflurane-anesthetized rats at 2nd, 4th, 6th, and 8th weeks post-operation. IVPG was evaluated based on the Euler equation. Results: Hypertension, polyuria and hypervolemia were observed in RH group from the 2nd, 4th, and 8th week, respectively. Marked left ventricle hypertrophy was evidenced at 6th (1.32 ± 0.28 vs 1.09 ± 0.09, p = 0.016) and 8th-week post-operation (1.34 ± 0.28 vs 1.16 ± 0.09, p = 0.014) that was more prominent in the posterior papillary muscle. Peak mitral E velocity in RH rats was higher than control at the 8th week (106.35 ± 16.04 vs 91.23 ± 10.82, p = 0.031). In contrast, tissue Doppler index, total IVPG, basal IVPG, and mid-to-apical IVPG showed no difference between groups throughout the experiment. Conclusions: Hypervolemia and RH lead to unclassified geometry in RH-associated cardiac remodeling. Blood pressure change precedes the change of preload during the development of RH cardiac remodeling.

Remote magnetic-guided ablation for three origins of idiopathic ventricular arrhythmias with right bundle branch block and superior axis.

BackgroundIdiopathic ventricular arrhythmias (IVAs) with right bundle branch block (RBBB) and superior axis commonly originate from posterior mitral annulus (PMA), the left ventricular (LV) posterior fascicle (LPF), and the LV posterior papillary muscles (PPM).HypothesisRemote magnetic navigation (RMN)‐guided ablation might be safe and effective for these three origins of IVAs.MethodsThirty consecutive IVA patients with RBBB and superior axis (11 MPA‐IVAs, 11 LPF‐IVAs, and 8 PPM‐IVAs) were included in this study. Electrical mapping and ablation with RMN were performed in the LV through a trans‐septal approach. Navigation index, defined as the ratio of total radiofrequency (RF) time and the time from first burn to last burn, was used to determine the efficiency of RMN‐guided ablation.ResultsThe overall acute success rate was achieved in 93% (PMA, 100%; LPF, 91%; PPM, 88%; p > 0.05). No complication occurred in this study. The procedure time of PPM‐IVAs group was 34 and 14 min longer when compared with MPA‐IVAs and LPF‐IVAs group, respectively, without an increase of X‐ray time. The mean navigation index was 0.45 ± 0.20. The PPM‐IVAs group had an underperforming navigation index value (0.29 ± 0.11) (p < 0.01), as longer RF time was required in the PPM‐IVAs group.ConclusionsRMN‐guided ablation can achieve a high acute success rate for IVAs with RBBB and superior axis. The lower navigation index for PPM‐IVAs indicated that increasing the RF time and improving the catheter contact should be considered when using RMN.

Anatomical variations of papillary muscles in human cadaveric hearts of Chhattisgarh, India

In both ventricles of the heart papillary muscles play important role for proper cardiac valvular function of heart. The present study was done to analyse the papillary muscles of heart with respect to the variations in their number, length, shape, position and pattern in both ventricles. Forty well preserved cadaveric human hearts were used for the study. The variations in the papillary muscles of both right and left ventricles were categorized, documented and photographed. In the right ventricle, authors observed 31.42% anterior, 34.3% posterior and 34.3% septal papillary muscles, and in the left ventricle, 41.7% anterior and 58.3% posterior papillary muscles. Classical papillary muscles were observed in 64.3% heart specimens in right ventricle and 55% in left ventricle. Authors found conical, pyramidal and broad apexed papillary muscles in 44.3%, 51.4% and 4.3% heart specimens respectively in right ventricle, whereas in left ventricle the corresponding values were 33.3%, 30% and 36.7%. Separate bases and fused apex pattern was observed in 24.3%, single base and divided apex in 55.7% heart specimens in right ventricle and in left ventricle in 45% and 43.3% heart specimens respectively. The length of anterior, posterior and septal papillary muscle in right ventricle was 1.27±0.45, 1.36±0.52, 0.92±0.54 cm respectively whereas in left ventricle, the mean length of anterior and posterior papillary muscles was 2.13±0.44 and 1.76±0.46 cm. In right ventricle mean thickness was 1.17±0.31cm whereas in left ventricle it was 2.16±0.32 cm. The papillary muscles has complex and variable anatomy. Knowledge of this variation to the cardiac surgeons during reparative surgical procedures conducted for mitral/ tricuspid valve replacement is of utmost importance to prevent untoward event.

Congestive heart failure in a young cat with excessive moderator bands (false tendons) in the left ventricle

ABSTRACT: Left ventricular false tendons are fibrous or fibromuscular bands that transverse the ventricular cavity and have no attachment to the mitral valve in many species. In cats it is considered a congenital defect that is rarely related to clinical disease and death in adult cats. A 45 days-old mixed breed cat had a history of inappetence since birth. At the physical exam the patient was lethargic and presented restrictive dyspnoea. At necropsy, there were marked ascites, hydrothorax, hepatomegaly with enhanced lobular pattern (nutmeg liver), and the lungs were markedly diminished (compressive pulmonary atelectasis). The heart was enlarged due to marked dilation of the cardiac chambers. Moreover, multiple slightly whitish and irregular cord-like structures were connecting the posterior papillary muscle to the interventricular septum (excessive moderator bands /left ventricular false tendons) at the left ventricle. Microscopically, these structures were characterized by a marked proliferation of fibrous connective tissue intermixed with Purkinje cells and well-differentiated cardiomyocytes lined by a single layer of endocardium. This study described a case of excessive moderator bands (left ventricular false tendons) in a young cat associated with congestive heart failure and death.

Tenascin C promotes valvular remodeling in two large animal models of ischemic mitral regurgitation

Ischemic mitral regurgitation (MR) is a frequent complication of myocardial infarction (MI) characterized by adverse remodeling both at the myocardial and valvular levels. Persistent activation of valvular endothelial cells leads to leaflet fibrosis through endothelial-to-mesenchymal transition (EMT). Tenascin C (TNC), an extracellular matrix glycoprotein involved in cardiovascular remodeling and fibrosis, was also identified in inducing epithelial-to-mesenchymal transition. In this study, we hypothesized that TNC also plays a role in the valvular remodeling observed in ischemic MR by contributing to valvular excess EMT. Moderate ischemic MR was induced by creating a posterior papillary muscle infarct (7 pigs and 7 sheep). Additional animals (7 pigs and 4 sheep) served as controls. Pigs and sheep were sacrificed after 6 weeks and 6 months, respectively. TNC expression was upregulated in the pig and sheep experiments at 6 weeks and 6 months, respectively, and correlated well with leaflet thickness (R = 0.68; p < 0.001 at 6 weeks, R = 0.84; p < 0.001 at 6 months). To confirm the translational potential of our findings, we obtained mitral valves from patients with ischemic cardiomyopathy presenting MR (n = 5). Indeed, TNC was also expressed in the mitral leaflets of these. Furthermore, TNC induced EMT in isolated porcine mitral valve endothelial cells (MVEC). Interestingly, Toll-like receptor 4 (TLR4) inhibition prevented TNC-mediated EMT in MVEC. We identified here for the first time a new contributor to valvular remodeling in ischemic MR, namely TNC, which induced EMT through TLR4. Our findings might set the path for novel therapeutic targets for preventing or limiting ischemic MR.

Abstract 15424: Tricuspid Valve Geometry and Right Heart Remodeling: Insights Into the Mechanism of Atrial Functional Tricuspid Regurgitation

Introduction: Functional tricuspid regurgitation (TR) caused by chronic atrial fibrillation with structurally normal tricuspid valve (TV) leaflets, normal right ventricular (RV) function, and dilated right atrium (RA), is considered as a new clinical entity, atrial functional TR (AF-TR). We sought to investigate TV geometry and right heart remodeling in AF-TR compared with ventricular functional TR with sinus rhythm (VF-TR). Methods: Transesophageal 3D echocardiography datasets of the TV and the RV were acquired in 51 symptomatic severe TR. 3D RV endocardial surfaces were reconstructed throughout the cardiac cycle and then postprocessed using semiautomated integration and segmentation software to calculate position of papillary muscle (PM) tips (Figure). Results: Compared with VF-TR, AF-TR had more dilated and posteriorly displaced annulus and less leaflet tethering angles with more prominent right atrium and smaller RV end-systolic volume. On the XY (annular) plane, the center of annulus was getting closer towards the anterior and posterior PM tips and was going away from the medial PM tip caused by prominent annular dilatation in AF-TR. On the Z axis, the position of each PM tip in AF-TR was not so much displaced apically as that in VF-TR. Multiple linear regression analyses revealed that right atrial volume and right atrial/RV end-systolic volume ratio were determinants of annular area and orientation in AF-TR, respectively (both P &lt;0.001). Additionally, the posteromedial directed component of posterior PM tip position and the apically directed component of the position of all 3 PM tips were independently associated with TV tethering angles of each leaflet in AF-TR (all P &lt;0.02). In subgroup analysis, massive to torrential AF-TR had a larger RV volume with more apically displaced PM tips than severe AF-TR. Conclusion: Right heart remodeling and its association with TV geometry differ between AF-TR and VF-TR, which offers distinctive therapeutic implications.