Congenital Aneurysm of the Muscular Ventricular Septum: Morphologic Evolution of the Septum

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Congenital aneurysms of the muscular interventricular septum are rare.

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The natural history is not known.

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A conservative approach buys time for evolution of a “thinned-out” septum.

Computed tomography imaging-identified location and electrocardiographic characteristics of left bundle branch area pacing in bradycardia patients

INTRODUCTION

Left bundle branch area pacing (LBBAP) is a novel physiological pacing modality. The relationship between the pacing lead tip location and paced electrocardiographic (ECG) characteristics remains unclear. The objectives are to determine the lead tip location within the interventricular septum (IVS) and assess the location-based ECG QRS duration (QRSd) and left ventricular activation time (LVAT).

METHODS

This multi-center study enrolled 50 consecutive bradycardia patients who met pacemaker therapy guidelines and received LBBAP implantation via the trans-ventricular septal approach. After at least 3 months post implant, 12-lead ECGs and pacing parameters were obtained. Cardiac computed tomography (CT) imaging was performed to assess the LBBAP lead tip distance from the LV blood pool.

RESULTS

Among the 50 patients, analyzable CT images were obtained in 42. In 23 of the 42 patients, the lead tips were within 2 mm to the LV blood pool (the LV subendocardial (LVSE) group), 13 between 2 mm and 4 mm (the Near-LVSE group), and the remaining 6 beyond 4 mm (the mid-LV septal (Mid-LVS) group). No significant differences in paced QRSd were found among the 3 groups (LVSE, 107±15 ms; Near-LVSE, 106±13 ms; Mid-LVS, 104±15 ms; P=0.87). LVAT in the LVSE (64±7 ms) was significantly shorter than in the Mid-LVS (72±8 ms; P<0.05), but not significantly different from that in the Near-LVSE (69±8 ms; P>0.05).

CONCLUSION

In routine LBBAP practice, paced narrow QRSd and fast LVAT, indicative of physiological pacing, was consistently achieved for lead tip location in the LV subendocardial or near LV subendocardial region. This article is protected by copyright. All rights reserved.

Interventricular septal hematoma detected by transesophageal echocardiography after congenital heart surgery in an infant: a case report

Background

Interventricular septal hematoma is an extremely rare complication following congenital heart surgery. During cardiac surgery, interventricular septal hematomas can be detected only by intraoperative transesophageal echocardiography. Here, we report an interesting case of interventricular septal hematoma that was accidentally found in an infant following ventricular septal defect (VSD) closure.

Case presentation

Transesophageal echocardiography images were acquired from a 1-month-old boy after surgical repair of a large (6.5 mm) perimembranous outlet VSD with interventricular septal flattening. Surgical correction was performed with auto-pericardium and 7–0 Prolene sutures. The patient was successfully weaned from cardiopulmonary bypass, and transesophageal echocardiography showed no VSD leakage and good ventricular function. However, approximately 30 min later, two anechoic masses were found within the interventricular septum, which were suspected to be interventricular septal hematomas; the larger mass measured 1.51 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\times $$\end{document}× 1.48 cm. The swollen interventricular septum showed decreased contractility and compressed both the right and left ventricles. However, there was no change in the size of hematomas or a significant hemodynamic instability for 30 min of observation. Therefore, expecting spontaneous resolution of the hematomas, the interventricular septum was not explored, and the patient was removed from cardiopulmonary bypass. On postoperative day 4, follow-up transthoracic echocardiography revealed thrombi filling the hematomas. The patient was discharged on postoperative day 15 and followed up with regular echocardiographic evaluations.

Conclusions

We describe a unique case of interventricular septal hematoma after VSD closure. Surgical manipulation of perimembranous VSD and injury of the septal perforating artery may contribute to the development of an interventricular septal hematoma. Moreover, conservative treatment and serial echocardiographic evaluation generally show gradual hematoma resolution in hemodynamically stable patients. Pediatric cardiac anesthesiologists should be aware of this rare complication after VSD repair.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-021-00552-4.

Identification of the building blocks of ventricular septation in monitor lizards (Varanidae)

Among lizards, only monitor lizards (Varanidae) have a functionally divided cardiac ventricle. The division results from the combined function of three partial septa, which may be homologous to the ventricular septum of mammals and archosaurs. We show in developing monitors that two septa, the 'muscular ridge' and 'bulbuslamelle', express the evolutionarily conserved transcription factors Tbx5, Irx1 and Irx2, orthologues of which mark the mammalian ventricular septum. Compaction of embryonic trabeculae contributes to the formation of these septa. The septa are positioned, however, to the right of the atrioventricular junction and they do not participate in the separation of incoming atrial blood streams. That separation is accomplished by the 'vertical septum', which expresses Tbx3 and Tbx5 and orchestrates the formation of the electrical conduction axis embedded in the ventricular septum. These expression patterns are more pronounced in monitors than in other lizards, and are associated with a deep electrical activation near the vertical septum, in contrast to the primitive base-to-apex activation of other lizards. We conclude that evolutionarily conserved transcriptional programmes may underlie the formation of the ventricular septa of monitors.

Specialized impulse conduction pathway in the alligator heart

Mammals and birds have a specialized cardiac atrioventricular conduction system enabling rapid activation of both ventricles. This system may have evolved together with high heart rates to support their endothermic state (warm-bloodedness) and is seemingly lacking in ectothermic vertebrates from which first mammals then birds independently evolved. Here, we studied the conduction system in crocodiles (Alligator mississippiensis), the only ectothermic vertebrates with a full ventricular septum. We identified homologues of mammalian conduction system markers (Tbx3-Tbx5, Scn5a, Gja5, Nppa-Nppb) and show the presence of a functional atrioventricular bundle. The ventricular Purkinje network, however, was absent and slow ventricular conduction relied on trabecular myocardium, as it does in other ectothermic vertebrates. We propose the evolution of the atrioventricular bundle followed full ventricular septum formation prior to the development of high heart rates and endothermy. In contrast, the evolution of the ventricular Purkinje network is strongly associated with high heart rates and endothermy.

Mammals and birds are referred to as ‘warm-blooded’ animals, because they maintain a constant high body temperature. This requires a lot of energy, so their bodies need to be well supplied with blood at all times. The hearts of mammals and birds contain two important structures that help them do this. The first is a full wall of muscle – called the ventricular septum – that divides the heart into left and right sides. The second is an electrical circuit made of specialized muscle cells that ensures that the heart beats fast enough by sending rapid electrical signals to the rest of the heart muscle. The circuit contains one group of cells in the ventricular septum, called the bundle of His, and another group termed the Purkinje network.

Reptiles, however, do not maintain high body temperatures and are instead often thought of as ‘cold-blooded’ animals. The hearts of reptiles do not need to pump blood around the body as quickly and have different structures from warm-blooded animals. For example, most reptile hearts do not have a fully developed ventricular septum. The only exceptions are crocodiles, alligators and their relatives (the ‘crocodilians’), which do.

Jensen, Boukens et al. therefore wanted to determine if a crocodilian heart also contained a specialized electrical circuit like those of birds and mammals. Previous studies that attempted to answer this question using only anatomical and electrical methods had yielded ambiguous results. As such, Jensen, Boukens et al. combined these methods with genetic techniques for a more detailed study.

First, the ventricular septum of American alligators, a species of crocodilian, was examined, and found to contain a narrow tissue structure that strongly resembled the bundle of His. Indeed, if this presumptive bundle of His was cut, the electrical circuit was broken. Additional genetic analysis of this structure confirmed that genes similar to those active in the mammalian bundle of His were also switched on in alligators. However, recordings of heart activity showed that heart rates and the spread of electrical signals were both slower in alligators than in warm-blooded animals. This suggests that, although alligators have evolved some specialized muscle cells (in the form of a bundle of His), their electrical circuit is still ‘incomplete’. The lack of a Purkinje network, for example, would explain why their heart rates remain slow like other reptiles’.

Together these findings add to the current understanding of how the heart works in different animals with varying requirements for energy and blood flow. Also, since crocodiles and warm-blooded birds both evolved from ancient reptiles, detailed descriptions of their heart structures could shed more light on how warm-bloodedness first developed.

[Comparison of early clinical effects of ablation with surgery treatment in patients with hypertrophic cardiomyopathy]

Objective: To compare the early clinical effect of septal myectomy and percutaneous transluminal septal myocardial ablation (PTMSA) on the left ventricular outflow obstruction and the rate of complication in patients with hypertrophic obstructive cardiomyopathy (HOCM). Methods: A total of 204 patients with HOCM who received septal reduction treatment were recruited. These patients were divided into two groups, surgery group (n=135) (65 patients with modified Morrow procedure, 70 patients with non-Morrow myomectomy) and PTMSA group (n=69). The baseline characteristics, disease status, other history of surgery and echocardiography parameters before and after septal reduction were collected, as well as the complication within 1 week after operation. Results: The mean age in surgery group was (46±14) years old, with 76 males (56.3%); mean age was (47±11) years old and with 51 males (73.9%) in PTMSA group. There was no significant difference in age, gender, the time of symptom and diagnosis, syncope, family history and atrial fibrillation between the two groups (all P>0.05). The proportion of mitral valve prolapse in the surgery group was higher than that in PTMSA group (75.8% vs 44.2%, P<0.05). Baseline left ventricular outflow tract (LVOT) gradient was comparable (82.7 mmHg in surgery group vs 77.7 mmHg in PTMSA group, P>0.05). The mean resting LVOT gradient after septal reduction therapy was lower (16.55 mmHg in surgery group, 26.68mmHg in PTMSA group) than that before operation, with lower gradient in surgery group (P<0.05). Compared with PTMSA group, the duration of hospitalization was longer in surgery group (P<0.05). There was similar rate of operation related complications in the two groups. Conclusions: Both septal reduction therapies can improve the LVOT obstruction, more significant in surgery group, but with longer hospital stay. The rate of operation related complication is similar in both groups.

Echocardiographic investigation of the mechanism underlying abnormal interventricular septal motion after open heart surgery

Background

Abnormal interventricular septal motion (ASM) is frequently observed after open heart surgery (OHS). The aim of this study was to investigate the incidence and temporal change of ASM, and its underlying mechanism in patients who underwent OHS using transthoracic echocardiography (TTE).

Methods

In total, 165 patients [60 ± 13 years, 92 (56%) men] who underwent coronary bypass surgery or heart valve surgery were consecutively enrolled in a prospective manner. TTE was performed preoperatively, at 3--6-month postoperatively, and at the 1-year follow-up visit. Routine TTE images and strain analysis were performed using velocity vector imaging.

Results

ASM was documented in 121 of 165 patients (73%) immediately after surgery: 26 patients (17%) presented concomitant expiratory diastolic flow reversal of the hepatic vein, 11 (7%) had inferior vena cava plethora, and 11 (7%) had both. Only 2 patients (1%) showed clinically discernible constriction. ASM persisted 3--6 months after surgery in 38 patients (25%), but only in 23 (15%) after 1 year. There was no difference in preoperative and postoperative peak systolic strain of all segments of the left ventricle (LV) between groups with or without ASM. However, systolic radial velocity (V_Rad) of the mid anterior-septum and anterior wall of the LV significantly decreased in patients with ASM.

Conclusion

Although ASM was common (74%) immediately after OHS, it disappeared over time without causing clinically detectable constriction. Furthermore, we consider that ASM might not be caused by myocardial ischemia, but by the decreased systolic V_Rad of the interventricular septum after pericardium incision.

Aneurysm of sinus of valsalva dissecting into the interventricular septum after aortic valve replacement: diagnosis by echocardiography and magnetic resonance imaging and treatment with surgical sealant

Aneurysm of the sinus of Valsalva that causes dissection of the interventricular septum is an extremely rare entity. In this report we describe a case of aneurysm of the sinus of Valsalva dissecting into the interventricular septum, from the base to mid septum, after aortic valve replacement. After the diagnosis was made by transthoracic echocardiography and magnetic resonance imaging, the patient was successfully treated with surgical sealant-mediated occlusion of the aneurysmal sac and cardiac resynchronization therapy used for the first time.