Transseptal approach versus retrograde aortic approach in mapping and ablation of ventricular arrhythmias from anterolateral papillary muscles.

INTRODUCTION: The anterior and lateral position of the anterolateral papillary muscle (ALPM) has found to be reached with better catheter stability and less mechanical bumping via the transseptal (TS) compared to the retrograde aortic (RA) approach. The aim of this study is to compare the TS and RA approaches on mapping and ablation of ventricular arrhythmias (VAs) arising from ALPMs. METHODS: Thirty-two patients with ALPM-VAs undergoing mapping and ablation via the TS approach were included and compared with 31 patients via the RA approach within the same period. Acute success was compared, as well as other outcomes including misinterpreted mapping results due to bumping, radiofrequency (RF) attempts, procedural time and success rate at 12-month follow-up. RESULTS: Acute success was achieved in more cases in the TS group (96.4% vs. 72.0%, p = .020). During activation mapping, bump-provoked premature ventricular complexes (PVCs) misinterpreted as clinical PVCs were more common in the RA group (30.0% vs. 58.3%, p = .036), leading to more RF attempts (3.5 ± 2.7 vs. 7.2 ± 6.8, p = .006). Suppression of VAs were finally achieved in the unsuccessful cases by changing to the alternative approach, but the procedural time was significantly less in the TS group (90.0 ± 33.0 vs. 113.7 ± 41.1 min, p = .027) with less need to change the approach, although follow-up success rates were similar (75.0% vs. 71.0%, p = .718). CONCLUSION: A TS rather than RA approach as the initial approach appears to facilitate mapping and ablation of ALPM-VAs, specifically by decreasing the possibility of misleading mapping results caused by bump-provoked PVC, and increase the acute success rate thereby.

Biomechanical evaluation of flash-frozen and cryo-sectioned papillary muscle samples by using sinusoidal analysis: cross-bridge kinetics and the effect of partial Ca2+ activation.

We examined the integrity of flash-frozen and cryo-sectioned cardiac muscle preparations (introduced by Feng and Jin, 2020) by assessing tension transients in response to sinusoidal length changes at varying frequencies (1-100 Hz) at 25 °C. Using 70-µm-thick sections, we isolated fiber preparations to study cross-bridge (CB) kinetics: preparations were activated by saturating Ca2+ as well as varying concentrations of ATP and phosphate (Pi). Our results showed that, compared to ordinary skinned fibers, in-series stiffness decreased to 1/2, which resulted in a decrease of isometric tension to 62%, but CB kinetics and Ca2+ sensitivity were little affected. The pCa study demonstrated that the rate constant of the force generation step (2πb) is proportionate to [Ca2+] at < 5 µM, suggesting that the activation mechanism can be described by a simple second order reaction. We also found that tension, stiffness, and magnitude parameters are related to [Ca2+] by the Hill equation, with a cooperativity coefficient of 4-5, which is consistent with the fact that Ca2+ activation mechanisms involve cooperative multimolecular interactions. Our results support the long-held hypothesis that Process C (Phase 2) represents the CB detachment step, and Process B (Phase 3) represents the force generation step. Moreover, we discovered that constant H may represent the work-performing step in cardiac preparations. Our experiments demonstrate excellent CB kinetics with two well-defined exponentials that can be more distinguished than those found using ordinary skinned fibers. Flash-frozen and cryo-sectioned preparations are especially suitable for multi-institutional collaborations nationally and internationally because of their ease of transportation.

A case of hypervirulent K1-ST23 Klebsiella pneumoniae endocarditis and papillary muscle rupture secondary to multiple site abscesses.

Hypervirulent Klebsiella pneumoniae (hvKP) causes multisite infections and abscesses. However, endocarditis is a rare presentation of hvKP infection. Herein, we report a case of K. pneumoniae native valve infective endocarditis secondary to community-acquired liver and prostate abscesses. The patient developed papillary muscle rupture, leading to mitral regurgitation, and underwent emergent mitral valve replacement. The diagnosis of endocarditis was confirmed microbiologically and histologically. The causative strain belonged to the hypermucoid K1 capsular genotype and possessed the rmpA gene. The genome sequence was deposited in GenBank under the accession number JAQZBZ000000000.

Evaluation of the prognostic value of papillary muscle-free strain in patients with hypertrophic cardiomyopathy.

BACKGROUND: The prognosis of hypertrophic cardiomyopathy (HCM) varies from mild disease with a normal life expectancy to heart failure and sudden cardiac death (SCD). The identification of patients who are at high risk for SCD remains challenging. AIMS: In this study, we evaluated the prognostic value of papillary muscle-free strain in HCM patients. METHODS AND RESULTS: Seventy-nine patients with a diagnosis of HCM were included in this study. Patients were divided into low/intermediate-risk (n = 57) and high-risk (n = 22) groups. Two-dimensional (2-D) echocardiography and strain imaging were performed for each patient. The mean age of the study population was 53.85 ± 15.88 years; 47 (59.5%) of them were male. During a mean follow-up duration of 74.45 ± 17.03 months, 12 patients died. A comparison of the low-intermediate and high-SCD risk groups revealed that patients in the high-SCD risk group had greater maximal wall thickness, interventricular septum thickness, posterior wall thickness, and left ventricular mass index (LVMI) and lower (less negative) global longitudinal, anterolateral papillary muscle (ALPM) and posteromedial papillary muscle (PMPM) free strain. Additionally, a history of syncope and ICD implantation were found to be more common in patients with high SCD risk scores. The SCD risk score was positively correlated with the global longitudinal strain, ALPM-free strain, and PMPM-free strain (r = .528, r = .658, and r = .600, respectively; p < .001 for all). Our results showed that the LVMI, presence of syncope, global longitudinal strain, and ALPM-free strain were predictors of death. CONCLUSIONS: Decreased papillary muscle-free strain values might have prognostic value in patients with HCM.

Echocardiography in the Recognition and Management of Mechanical Complications of Acute Myocardial Infarction.

PURPOSE OF REVIEW: Although rare, the development of mechanical complications following an acute myocardial infarction is associated with a high morbidity and mortality. Here, we review the clinical features, diagnostic strategy, and treatment options for each of the mechanical complications, with a focus on the role of echocardiography. RECENT FINDINGS: The growth of percutaneous structural interventions worldwide has given rise to new non-surgical options for management of mechanical complications. As such, select patients may benefit from a novel use of these established treatment methods. A thorough understanding of the two-dimensional, three-dimensional, color Doppler, and spectral Doppler findings for each mechanical complication is essential in recognizing major causes of hemodynamic decompensation after an acute myocardial infarction. Thereafter, echocardiography can aid in the selection and maintenance of mechanical circulatory support and potentially facilitate the use of a percutaneous intervention.

Multimodal imaging diagnosis of left ventricular outflow tract obstruction due to abnormal papillary muscle insertion.

This article reports a case of LV outflow obstruction caused by abnormalities of the anterior leaflet connection of the mitral papillary muscle, aiming to highlight the importance of combined multimodal imaging in the differential diagnosis of the etiology of LV outflow obstruction.

The effects of nickel chloride on papillary muscle contractility under normothermic and hypothermic conditions: Comparison of active and hibernating ground squirrels (Urocitellus undulatus) with Wistar rats.

Extracellular Ca2+ plays a pivotal role in the regulation of cardiac contractility under normal and extreme conditions. Here, by using nickel chloride (NiCl2), a non-specific blocker of extracellular Ca2+ influx, we studied the input of extracellular Ca2+ on the regulation of papillary muscle (PM) contractility under normal and hypothermic conditions in ground squirrels (GS), and rats. By measuring isometric force of contraction, we studied how NiCl2 affects force-frequency relationship and the rest effect in PM of these species at 30 °C and 10 °C. We found that at 30 °C 1.5 mM NiCl2 significantly reduced force of contraction across entire frequency range in active GS and rats, whereas in hibernating GS force of contraction was reduced at low and high frequency range. Additionally, NiCl2 evoked spontaneous contractility in rats but not GS PM. The rest effect was significantly reduced by NiCl2 for active GS and rats but not hibernating GS. At 10 °C, NiCl2 fully reduced contractility in active GS and, to a lesser extent, in rats, whereas in hibernating GS it was significant only at 0.3 Hz. The rest effect was significantly reduced by NiCl2 in both active and hibernating GS, whereas it was unmasked in rats that had high contractility under hypothermic conditions in control. Our results show a significant contribution of extracellular Ca2+ to myocardial contractility in GS not only in active but also in hibernating states, especially under hypothermic conditions, whereas limitation of extracellular Ca2+ influx in rats under hypothermia can play protective role for myocardial contractility.

Muscularization of the chordae tendinea of the mitral anterior papillary muscle.

The chordae tendineae, described as fibro-collagenous structures, support the leaflets of the atrioventricular valves of the heart in various ways. The chordae tendineae are composed of collagen and elastic fibers. They connect to the ventricular side of the valve leaflets' free border and hinder the leaflets from swinging back into the atrial cavity during systole. Mitral valve chordae tendineae have been classified using a variety of classification systems. To our knowledge, we report a variant chordae tendinea that has yet to be described in the literature. The variant, present only on the mitral anterior papillary muscle, did not show the characteristic appearance of the chorda tendineae. Muscular fibers were observed extending from a larger than usual mitral anterior papillary muscle, inserting into the rough zone of the anterior leaflet. Several tendinous primary and secondary true leaflet chordae emerge from the apical portion of the anterior papillary muscle, inserting into the anterior leaflet's free edge and rough zone. Contraction of this muscular chorda during systole could disrupt the mechanics of valvular closure and result in possible regurgitation across the mitral valve. Additionally, this structure may be subject to rupture during myocardial infarction, leading to valvular dysfunction. The developmental connection between the chordae and papillary muscles could explain the anomalous muscularization of the chordae tendineae observed in this case.

Acute mitral regurgitation with and without acute heart failure.

Acute severe mitral regurgitation (MR) is rare, but often leads to cardiogenic shock, pulmonary edema, or both. Most common causes of acute severe MR are chordae tendineae (CT) rupture, papillary muscle (PM) rupture, and infective endocarditis (IE). Mild to moderate MR is often seen in patients with acute myocardial infarction (AMI). CT rupture in patients with floppy mitral valve/mitral valve prolapse is the most common etiology of acute severe MR today. In IE, native or prosthetic valve damage can occur (leaflet perforation, ring detachment, other), as well as CT or PM rupture. Since the introduction of percutaneous revascularization in AMI, the incidence of PM rupture has substantially declined. In acute severe MR, the hemodynamic effects of the large regurgitant volume into the left atrium (LA) during left ventricular (LV) systole, and in turn back into the LV during diastole, are profound as the LV and LA have not had time to adapt to this additional volume. A rapid, but comprehensive evaluation of the patient with acute severe MR is essential in order to define the underline cause and apply appropriate management. Echocardiography with Doppler provides vital information related to the underlying pathology. Coronary arteriography should be performed in patients with an AMI to define coronary anatomy and need for revascularization. In acute severe MR, medical therapy should be used to stabilize the patient before intervention (surgery, transcatheter); mechanical support is often required. Diagnostic and therapeutic steps should be individualized, and a multi-disciplinary team approach should be utilized.

Papillary muscle rupture after transcatheter aortic valve implantation: A case report and literature review.

We present a case of posterior papillary muscle rupture associated with severe eccentric mitral regurgitation following transcatheter aortic valve implantation, that was successfully treated with transcatheter edge to edge mitral repair and review similar cases in literature.

Transcatheter edge-to-edge mitral valve repair for post-myocardial infarction papillary muscle rupture and acute heart failure: A systematic review.

Papillary muscle rupture (PMR) is a rare complication of acute myocardial infarction (AMI) associated with high mortality and morbidity. Surgery is the gold-standard treatment for these patients, but it is burdened by a high perioperative risk due to hemodynamic instability. Mitral transcatheter edge-to-edge repair (M-TEER) was reported to be safe and effective in unstable patients with significant mitral regurgitation. However, data in patients with post-AMI PMR are limited to a few case reports. In this review, we summarized all data available regarding percutaneous treatment of post-AMI PMR. These results show that M-TEER is safe and effective in this setting with low in-hospital mortality and complications and high rate of significant mitral regurgitation reduction.

Prevalence of papillary muscle hypertrophy in fabry disease.

BACKGROUND AND AIMS: Fabry disease (FD) is an X-linked genetic lysosomal disease, in which a deficit in the alpha-galactosidase A enzyme results in lysosomal build-up of globotriaosylceramide in several organs, causing cardiac, renal and cerebrovascular complications. The aim of this study was to assess the prevalence of papillary muscle hypertrophy (PMH) in patients with FD. METHODS: A group of 63 patients with FD and a positive genetic diagnosis were studied and were divided into two groups: one included 24 patients with FD and LVH and another group included 39 patients with FD and without LVH. Papillary muscles were measured from the left parasternal short axis view, defining PMH as a diastolic thickness greater than 11 mm in any diameter. RESULTS: Patients with FD and LVH had a high prevalence of anterolateral PMH (66.6%), and such prevalence was lower for the posteromedial PMH (33.3%). However, patients who had not yet developed LVH had a high prevalence of anterolateral PMH (33.3%). CONCLUSIONS: Patients with FD in the pre-clinical stage (without LVH) have a high prevalence of PMH, especially involving the anterolateral papillary muscle. This finding could be an early marker for the development of LVH, allowing to suspect the disease during its early stages, and begin enzyme replacement therapy in the appropriate patients.

Use of a QDOT MICRO catheter to identify a premature ventricular contraction origin in the right ventricular anterior papillary muscle in a repaired truncus arteriosus.

The ventricular papillary muscles (VPMs) can be a source of premature ventricular contractions (PVCs). Catheter ablation of VPM PVCs is challenging because of the anatomical complexity, such as the apical structures in proximity to the ventricular walls. The QDOT MICRO catheter (Biosense Webster, Diamond Bar, CA, USA) has microelectrodes embedded along the circumference of its distal tip and can provide information on which side of its tip myocardial activation is earlier. This repaired truncus arteriosus case demonstrates the usefulness of the microelectrode recording in identifying a PVC origin in a right VPM apex close to the right ventricular anterior wall.

Extracorporeal life support in mitral papillary muscle rupture: Outcome of multicenter study.

BACKGROUND: Post-acute myocardial infarction papillary muscle rupture (post-AMI PMR) may present variable clinical scenarios and degree of emergency due to result of cardiogenic shock. Veno-arterial extracorporeal life support (V-A ECLS) has been proposed to improve extremely poor pre- or postoperative conditions. Information in this respect is scarce. METHODS: From the CAUTION (meChanical complicAtion of acUte myocardial infarcTion: an InternatiOnal multiceNter cohort study) database (16 different Centers, data from 2001 to 2018), we extracted adult patients who were surgically treated for post-AMI PMR and underwent pre- or/and postoperative V-A ECLS support. The end-points of this study were in-hospital survival and ECLS complications. RESULTS: From a total of 214 post-AMI PMR patients submitted to surgery, V-A ECLS was instituted in 23 (11%) patients. The median age was 61.7 years (range 46-81 years). Preoperatively, ECLS was commenced in 10 patients (43.5%), whereas intra/postoperative in the remaining 13. The most common V-A ECLS indication was post-cardiotomy shock, followed by preoperative cardiogenic shock and cardiac arrest. The median duration of V-A ECLS was 4 days. V-A ECLS complications occurred in more than half of the patients. Overall, in-hospital mortality was 39.2% (9/23), compared to 22% (42/219) for the non-ECLS group. CONCLUSIONS: In post-AMI PMR patients, V-A ECLS was used in almost 10% of the patients either to promote bridge to surgery or as postoperative support. Further investigations are required to better evaluate a potential for increased use and its effects of V-A ECLS in such a context based on the still high perioperative mortality.

Hydatid cyst of papillary muscle concomitant with brain involvement.

BACKGROUND: Cardiac hydatidosis is a rare disease and the subepicardial region of the left ventricular is commonly affected. However, papillary muscle concomitant with brain involvement has not been previously reported. CASE: We report a 44 years old man who complained of headache along with no cardiac symptoms. The patient was diagnosed with cerebral hydatid cyst. Through preoperative cardiac consultant, transthoracic echocardiography revealed cardiac hydatid cyst confined to the anterolateral papillary muscle. Medical treatment was started promptly and successful surgical excision of all cysts was performed. The patient had an uneventful recovery and follow up at 3 months. CONCLUSION: Early diagnosis of cardiac HC by echocardiography is recommended in all patients with hydatid disease, regardless of HC location.

ECPELLA as the bridge to surgery in patients with cardiogenic shock due to post-infarct papillary muscle rupture: management of mechanical circulatory support during operation.

Papillary muscle rupture is a fatal complication with a high operative mortality. Most patients experience cardiogenic shock and hypoxia due to pulmonary edema caused by severe mitral regurgitation. Although preoperative stabilization using a mechanical assist device potentially improves surgical outcomes, an appropriate strategy has not yet been established. ECPELLA, combining venoarterial extracorporeal membrane oxygenation and Impella, has the potential to stabilize preoperative status and improve outcome in patients with refractory cardiogenic shock due to papillary muscle rupture. Herein, we present 3 cases involving the efficacy of ECPELLA and our tips of surgical and ECPELLA management in patients with papillary muscle rupture.

Aerobic Exercise Training Improves Calcium Handling and Cardiac Function in Rats with Heart Failure Resulting from Aortic Stenosis.

Aerobic exercise training (AET) has been used to manage heart disease. AET may totally or partially restore the activity and/or expression of proteins that regulate calcium (Ca2+) handling, optimize intracellular Ca2+ flow, and attenuate cardiac functional impairment in failing hearts. However, the literature presents conflicting data regarding the effects of AET on Ca2+ transit and cardiac function in rats with heart failure resulting from aortic stenosis (AoS). This study aimed to evaluate the impact of AET on Ca2+ handling and cardiac function in rats with heart failure due to AoS. Wistar rats were distributed into two groups: control (Sham; n = 61) and aortic stenosis (AoS; n = 44). After 18 weeks, the groups were redistributed into: non-exposed to exercise training (Sham, n = 28 and AoS, n = 22) and trained (Sham-ET, n = 33 and AoS-ET, n = 22) for 10 weeks. Treadmill exercise training was performed with a velocity equivalent to the lactate threshold. The cardiac function was analyzed by echocardiogram, isolated papillary muscles, and isolated cardiomyocytes. During assays of isolated papillary muscles and isolated cardiomyocytes, the Ca2+ concentrations were evaluated. The expression of regulatory proteins for diastolic Ca2+ was assessed via Western Blot. AET attenuated the diastolic dysfunction and improved the systolic function. AoS-ET animals presented an enhanced response to post-rest contraction and SERCA2a and L-type Ca2+ channel blockage compared to the AoS. Furthermore, AET was able to improve aspects of the mechanical function and the responsiveness of the myofilaments to the Ca2+ of the AoS-ET animals. AoS animals presented an alteration in the protein expression of SERCA2a and NCX, and AET restored SERCA2a and NCX levels near normal values. Therefore, AET increased SERCA2a activity and myofilament responsiveness to Ca2+ and improved the cellular Ca2+ influx mechanism, attenuating cardiac dysfunction at cellular, tissue, and chamber levels in animals with AoS and heart failure.

An unusual origin of a papillary muscle of the right ventricle.

Knowledge of anatomical variations of the heart are important to cardiac surgeons, cardiologists, and radiologist. During routine dissection of a 77-year-old male cadaver, we observed an unusual origin of a papillary muscle of the right ventricle arising from the atrioventricular aspect of the moderator band. This papillary muscle was 6.7mm long and 2.6mm wide. It gave rise to two chordae tendineae: one to the inferior (posterior) papillary muscle of the right ventricle and one directly to the inferior (posterior) leaflet of the tricuspid valve. Variants of the internal anatomy of the heart as exemplified in the present case report should be born in mind during image interpretation and invasive procedures of the right ventricle of the heart.

Morphology of papillary muscles in the ventricles of heart - a review and meta-analysis.

OBJECTIVE: To review the morphology of papillary muscles in both the ventricles of heart. METHODS: The articles were collected from databases such as MEDLINE etc. using Google as the search engine. Keywords used were papillary muscle morphology, papillary muscle dimensions, papillary muscle blood supply, papillary muscle histology, papillary muscle development and papillary muscle biomechanical properties. Studies were included if they assessed the aforesaid features of papillary muscles. Thirty-four studies were included in the review. Meta-analysis was done for number of right and left ventricular papillary muscles and dimensions of right ventricular papillary muscles. The data obtained from these studies was synthesized, pooled and all analyses were performed using R Statistical Software (v4.1.2; R Core Team 2021) with R package meta version 5.5-0. RESULTS: Marked difference existed between papillary muscles of right and left ventricles. In right ventricle, one anterior (76%), one posterior (38%) and one septal (30%) papillary muscle were most common. In left ventricle, one anterior (46%) and two posterior papillary muscles (26%) were most common. In both the ventricles, commonly observed gross appearances of papillary muscles were conical and flat-topped. Papillary muscles were lengthier in left ventricle than right ventricle. Anterior papillary muscle was 1.36cm long, 1.36cm broad and 0.64cm thick in right ventricle. It was the largest in both right and left ventricles. CONCLUSION: The morphology and measurements of papillary muscles vary significantly. Thorough knowledge of these variations will help surgeons to determine appropriate surgical repair procedures for the valve and subvalvular apparatus.

Acute inferior myocardial infarction combined with papillary muscle rupture: A case report. / 急性下壁心肌梗死合并乳头肌断裂1例.

The incidence of acute myocardial infarction (AMI) is increasing. Acute papillary muscle rupture is one of the serious and rare mechanical complications of AMI, which occurs mostly in inferior and posterior myocardial infarction. A patient with acute inferior myocardial infarction developed pulmonary edema and refractory shock, followed by cardiac arrest. After cardiopulmonary resuscitation (CPR), revascularization of criminal vessels was carried out by emergency percutaneous transluminal coronary angioplasty (PTCA) under the support of intra-aortic balloon pump (IABP) and extra corporeal membrane oxygenation (ECMO). Although the patient was given a chance for surgery, his family gave up treatment due to unsuccessful brain resuscitation. It reminds that mechanical complications such as acute papillary muscle rupture, valvular dysfunction and rupture of the heart should be highly suspected when cardiogenic pulmonary edema and cardiogenic shock are difficult to correct in acute inferior myocardial infarction. Echocardiogram and surgery should be put forward when revascularization of criminal vessels is available.