Pitfalls and tips for lumenless lead extraction inserted deep within the ventricular septum

Key Clinical Message

This case highlights the pitfalls and provides tips for the extraction of deeply implanted lumenless leads, and encourages careful lead selection in the current era of widespread left bundle branch area pacing.

Abstract

The extraction of cardiovascular implantable electronic device leads is sometimes complicated. We describe a case with difficult but successful extraction of SelectSecure, a lumenless permanent pacemaker lead, implanted deep in the ventricular septum, highlighting its pitfalls and tips in the current era of left bundle branch area pacing.

Epidemiology of Cardiac Myxoma in the Kingdom of Bahrain

BACKGROUND

Cardiac myxomas (CM) are the most prevalent type of primary cardiac tumour. The majority of primary cardiac tumours, including CM, are found to be benign. In the context of this study, the objective was to investigate and analyse the experience of CM over a period of 10 years, specifically in Bahrain. By examining this particular subset of cardiac tumours, valuable insights can be gained regarding their prevalence, clinical presentation, diagnostic methods, treatment approaches, and outcomes in the Bahraini population.

METHODS

We retrospectively evaluated the medical records of 20 patients who presented with CM at the Mohammed bin Khalifa bin Salman Al Khalifa Specialist Cardiac Centre in the Kingdom of Bahrain from January 2010 to January 2021. All patients had transthoracic echocardiography to establish a preoperative diagnosis. All of the patients underwent an operation using the median sternotomy, and a histopathology examination confirmed the final diagnosis.

RESULTS

The mean age at the time of presentation was 57 (± 18.1) years, ranging from 17 to 80 years, and 55% (12 patients) were female. Dyspnea (n=8, 40%) and peripheral embolism (n=4, 20%), which include cerebrovascular accidents and acute monocular vision loss, were the most frequently observed symptoms. The largest diameter of the myxoma was 5.1 cm (±1.7). The left atrium was the predominant location for myxoma formation (n=16, 80%), with the majority of the myxomas attached to the atrial septum.

CONCLUSION

CM poses a significant risk of cardiac and systemic complications. Early detection and timely gross-complete resection result in excellent early and long-term outcomes.

Interventricular Septal Hematoma Complicating Ventricular Assist Device Placement in an Infant: Case Report and Review of the Literature

Interventricular septal hematoma is a rare and life-threatening complication of pediatric cardiac surgery. Commonly seen following ventricular septal defect repair, it has also been associated with ventricular assist device (VAD) placement. Although conservative management is usually successful, operative drainage of interventricular septal hematoma occurring in pediatric patients undergoing VAD implantation should be considered.

Procedural Outcomes of Pulmonary Atresia Intact Ventricular Septum in Neonates: A Multicenter Study

BACKGROUND

Multicenter contemporary data describing short-term outcomes following initial interventions of neonates with pulmonary atresia intact ventricular septum (PA-IVS) are limited. This multicenter study aims to describe characteristics and outcomes of PA-IVS neonates following their initial catheter or surgical intervention and identify factors associated with major adverse cardiac events (MACE).

METHODS

Neonates with PA-IVS who underwent surgical or catheter intervention between 2009-2019 in 19 centers were reviewed. Risk factors for MACE, defined as cardiopulmonary resuscitation, mechanical circulatory support, stroke, or in-hospital mortality, were analyzed using multivariable logistic regression model.

RESULTS

We reviewed 279 neonates: 79 (28%) underwent right ventricular decompression, 151 (54%) underwent systemic-to-pulmonary shunt or ductal stent placement only, 36 (13%) underwent right ventricular decompression with shunt or ductal stent placement, and 11 (4%) underwent transplantation. MACE occurred in 57 patients (20%): 26 (9%) received mechanical circulatory support, 37 (13%) received cardiopulmonary resuscitation, 16 (6%) suffered stroke, 23 (8%) died. The presence of two major coronary artery stenoses (adjusted OR: 4.99; 95% CI: 1.16-21.39) and lower weight at first intervention (adjusted OR: 1.52, 95% CI: 1.01-2.27) were significantly associated with MACE. Coronary ischemia was the most frequent presumed mechanism of death (n=10).

CONCLUSIONS

In a multicenter cohort, one in five neonates with PA-IVS experienced MACE following their initial intervention. Patients with two major coronary artery stenoses or lower weight at time of initial procedure were most likely to experience MACE and warrant vigilance during pre-intervention planning and post-intervention management.

Isolated Ventricular Septal Aneurysm: A Differential Diagnosis for a Right Sinus of Valsalva Aneurysm

BACKGROUND A ventricular septal aneurysm (VSA) is rare and almost always an incidental finding on cardiac imaging. It is rarely an isolated phenomenon and is more commonly associated with other forms of congenital heart disease such a ventricular septal defect (VSD). Differentiating a ventricular septal aneurysm from an aneurysm of the right sinus of Valsalva is crucial as the latter usually has a more aggressive course and may require surgical intervention. Cardiac computed tomography (cardiac CT) or cardiac magnetic resonance imaging (CMR) may help confirm the diagnosis. CASE REPORT We report a case of a 42-year-old obese Japanese man with a past medical history of hyperlipidemia who described occasional effort-related palpitations when climbing stairs over the past few months but no anginal symptoms. Echocardiogram revealed normal left ventricular systolic with a presumed right sinus of Valsalva aneurysm measuring around 1.5 cm. A coronary CTA was obtained to further delineate the aneurysm and revealed normal CT angiographic appearance of a right dominant coronary artery circulation with a small aneurysmal outpouching of the membranous ventricular septum measuring 13×17 mm without any evidence of shunting, along with focal calcification of the medial aspect of the tricuspid annulus. The right sinus of Valsalva appeared normal on coronary CTA. CONCLUSIONS Membranous ventricular septal aneurysm is a rare condition that is almost always an incidental finding on echocardiography and can be mistaken for an aneurysm of the right sinus of Valsalva. Multimodality imaging and high degree of clinical suspicion are needed to accurately diagnose a ventricular septal aneurysm and to achieve favorable outcomes. A VSA usually has a benign course and is rarely a cause of arrythmia, right ventricular outflow obstruction, or valvular insufficiency.

Incidental Asymptomatic Giant Hydatid Cyst of the Interventricular Septum Bulging Into the Right Ventricle

Hydatid disease is caused by the larvae of Echinococcus granulosus. Domestic animals like cats and dogs are the primary carriers of echinococcal organisms. This parasitosis is still endemic in some particular regions of the world. The cardiac hydatid cyst is an exceptional infection. We report a case of an asymptomatic giant cardiac hydatid cyst in the interventricular septum (IVS) protruding in the right ventricular diagnosed incidentally by scan tomography during acute pancreatitis emergency. Transthoracic echocardiography revealed a cystic mass in the IVS bulging into the right ventricle. The diagnosis was confirmed by a cardiac CT scan.

A neurological presentation caused by brain metastases in a dog with interventricular septal hemangiosarcoma

BACKGROUND

Brain metastases are well known for disseminated hemangiosarcoma involving the right atrium/auricle.

CASE REPORT

An 8-year-old male Australian Shepherd Dog presented with a 3-day history of circling to the left. A neurological examination revealed obtunded mentation, right hemi-inattention, bilateral strabismus towards the left side and absent physiological nystagmus. In addition, the dog had muffled heart sounds on auscultation and exercise-induced weakness. Laboratory findings included hypercoagulability and marked elevation in the C-reactive protein concentration. Electrocardiography detected a sinus rhythm with right bundle-branch block and ventricular bigeminy. Echocardiography revealed an extensive interventricular septal mass. Due to the grave prognosis, the owners elected for euthanasia, and a complete necropsy was performed. The main pathological findings were an interventricular septal and left ventricular hemangiosarcoma, with metastases in the brain, lungs, spleen and adrenal glands. No evidence of tumour infiltration was found in the right atrium.

CONCLUSION

To the authors' knowledge, this is the first report of neurological signs due to confirmed brain metastases in a dog with interventricular septal hemangiosarcoma. Although the right atrium is the main location for cardiac hemangiosarcoma, the interventricular septum should be evaluated in all cases.

Extremely late presentation of children with transposition the great arteries

We present three cases of primary arterial switch operation for extremely late presenting transposition the great arteries with intact ventricular septum: a 7-year-old female, 3-year-old male, and 6-year-old female. Two patients were discharged on postoperative day 9 and 11, the other developed hemodynamic instability 12 h after surgery and died due to left ventricular failure and pulmonary hypertension. Left ventricular mass index >35 g·m^-2 and left ventricular posterior wall >4 mm are criteria for a primary arterial switch operation. Circulatory support post- or intraoperatively might provide better results. Two patients survived without extracorporeal membrane oxygenation or nitric oxide.

Swiss-cheese ventricular septal defect closure by combination sandwich patch

A 7-year-old boy with a history of neonatal pulmonary artery banding underwent almost complete closure of a sieve-like "Swiss-cheese" ventricular septal defect, using a combination sandwich patch technique through a right ventriculotomy. Although defects existed in the high-, mid-, and low-trabecular septa, a right ventriculotomy and division of the muscle trabeculations continuing the septal and moderator bands helped delineate the edges of the defects. Although patients with "Swiss-cheese" ventricular septal defects may be candidates for a Fontan operation conventionally, a combination patch technique could be considered the procedure of choice.

Pros and Cons of Left Bundle Branch Pacing: A Single-Center Experience

BACKGROUND

Left bundle branch pacing (LBBP) has recently emerged as a promising alternative modality for conduction system pacing. However, limited real-world data exists on the advantages and complications associated with LBBP. We analyzed the Rush conduction system pacing registry on LBBP to assess the success rates and complications associated with LBBP.

METHODS

All patients with an indication for permanent pacemaker or cardiac resynchronization therapy that underwent LBBP for various reasons from June 2018 to April 2020 were included in the analysis.

RESULTS

A total of 57 of 59 patients underwent successful LBBP (success rate 97%). The average follow-up duration was 6.2±5 months. The implanted devices included 38 dual-chamber pacemakers, 17 cardiac resynchronization therapy defibrillators, and 2 cardiac resynchronization therapy pacing systems. The most common reason for performing LBBP was a high His-Bundle pacing threshold (n=23) at implant. The mean LBBP capture threshold at implant was 0.62±0.21 V at 0.4 ms which remained stable during follow-up at 0.65±0.68 V at 0.4ms. In 21 patients with cardiomyopathy, there was a significant improvement in left ventricle ejection fraction from 30±11% to 42±15%. A total of 7 lead-related complications (12.3%) were noted in the follow-up period. Three patients (5.3%) required lead revision during the follow-up period. Interventricular septal perforation occurred (as late sequela) after 2 weeks in one patient.

CONCLUSIONS

LBBP can be achieved with a high success rate and low capture thresholds. Left ventricular dysfunction improved significantly during follow-up. Lead-related complications were relatively common occurring in 12.3% of initially successful implants. Lead revision was required in 3 (5%) of patients.

Image Segmentation of the Ventricular Septum in Fetal Cardiac Ultrasound Videos Based on Deep Learning Using Time-Series Information

Image segmentation is the pixel-by-pixel detection of objects, which is the most challenging but informative in the fundamental tasks of machine learning including image classification and object detection. Pixel-by-pixel segmentation is required to apply machine learning to support fetal cardiac ultrasound screening; we have to detect cardiac substructures precisely which are small and change shapes dynamically with fetal heartbeats, such as the ventricular septum. This task is difficult for general segmentation methods such as DeepLab v3+, and U-net. Hence, here we proposed a novel segmentation method named Cropping-Segmentation-Calibration (CSC) that is specific to the ventricular septum in ultrasound videos in this study. CSC employs the time-series information of videos and specific section information to calibrate the output of U-net. The actual sections of the ventricular septum were annotated in 615 frames from 421 normal fetal cardiac ultrasound videos of 211 pregnant women who were screened. The dataset was assigned a ratio of 2:1, which corresponded to a ratio of the training to test data, and three-fold cross-validation was conducted. The segmentation results of DeepLab v3+, U-net, and CSC were evaluated using the values of the mean intersection over union (mIoU), which were 0.0224, 0.1519, and 0.5543, respectively. The results reveal the superior performance of CSC.

Septal Reduction Using Transvenous Intramyocardial Cerclage Radiofrequency Ablation: Preclinical Feasibility

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Surgical myectomy is morbid and transcoronary alcohol septal ablation can result in geographic miss or occasional nontarget injury.

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We developed a transvenous intraseptal radiofrequency ablation technique (cerclage ablation method) to overcome the shortcomings of surgical myectomy and alcohol septal ablation.

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We delivered dedicated intraseptal radiofrequency ablation catheter into the ventricular septum through the coronary sinus and a septal vein. The ablated volume of myocardium was larger at higher electrode temperatures and using an irrigated-ablation mode in vitro. Cerclage ablation was successful in all in vivo attempts and induced a focal regional wall motion abnormality at later follow-up.

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This study presents in vivo evidence of the feasibility, effectiveness, and safety of cerclage ablation method to debulk interventricular septal myocardium.

Debulking of left ventricular septal mass is typically accomplished using surgical myectomy, which is morbid, or using transcoronary alcohol septal ablation, which can result in geographic miss and occasional catastrophic nontarget coronary injury. The authors developed and tested operational parameters in vitro and vivo for a device to accomplish transvenous intraseptal radiofrequency ablation to reduce ventricular septal mass using a technique derived from mitral cerclage, which the authors call cerclage ablation. Cerclage ablation appeared feasible in vitro and safe and effective in vivo. Cerclage ablation is an attractive new approach to debulk the interventricular septum in obstructive hypertrophic cardiomyopathy. These data support clinical investigation.

Short-Term Hemodynamic and Electrophysiological Effects of Cardiac Resynchronization by Left Ventricular Septal Pacing

BACKGROUND

Cardiac resynchronization therapy (CRT) is usually performed by biventricular (BiV) pacing. Previously, feasibility of transvenous implantation of a lead at the left ventricular (LV) endocardial side of the interventricular septum, referred to as LV septal (LVs) pacing, was demonstrated.

OBJECTIVES

The authors sought to compare the acute electrophysiological and hemodynamic effects of LVs with BiV and His bundle (HB) pacing in CRT patients.

METHODS

Temporary LVs pacing (transaortic approach) alone or in combination with right ventricular (RV) (LVs+RV), BiV, and HB pacing was performed in 27 patients undergoing CRT implantation. Electrophysiological changes were assessed using electrocardiography (QRS duration), vectorcardiography (QRS area), and multielectrode body surface mapping (standard deviation of activation times [SDAT]). Hemodynamic changes were assessed as the first derivative of LV pressure (LVdP/dtmax).

RESULTS

As compared with baseline, LVs pacing resulted in a larger reduction in QRS area (to 73 ± 22 μVs) and SDAT (to 26 ± 7 ms) than BiV (to 93 ± 26 μVs and 31 ± 7 ms; both p < 0.05) and LVs+RV pacing (to 108 ± 37 μVs; p < 0.05; and 29 ± 8 ms; p = 0.05). The increase in LVdP/dtmax was similar during LVs and BiV pacing (17 ± 10% vs. 17 ± 9%, respectively) and larger than during LVs+RV pacing (11 ± 9%; p < 0.05). There were no significant differences between basal, mid-, or apical LVs levels in LVdP/dtmax and SDAT. In a subgroup of 16 patients, changes in QRS area, SDAT, and LVdP/dtmax were comparable between LVs and HB pacing.

CONCLUSIONS

LVs pacing provides short-term hemodynamic improvement and electrical resynchronization that is at least as good as during BiV and possibly HB pacing. These results indicate that LVs pacing may serve as a valuable alternative for CRT.

The Mitral Coaptation to Ventricular Septal Space: Two- and Three-Dimensional Transesophageal Echocardiographic Assessment

OBJECTIVES

To assess the dimensions and changes in the CSEPT (space between the ventricular septum and mitral coaptation point) before and after cardiopulmonary bypass (CPB) and to compare patients with and without aortic valve stenosis (AS) undergoing cardiac surgery.

DESIGN

Retrospective review of intraoperative transesophageal echocardiographic examinations.

SETTING

Single academic medical center.

PARTICIPANTS

The study comprised 91 elective cardiac surgical patients-30 with AS scheduled for aortic valve replacement and 61 without AS (non-AS).

INTERVENTIONS

Two- and 3-dimensional (2D and 3D) analysis of the CSEPT before and after CPB.

MEASUREMENTS AND MAIN RESULTS

Assessment of the CSEPT distances and areas was performed using 2D and 3D imaging before and after CPB. Two-dimensional measures of CSEPT distances were performed using midesophageal 5-chamber and long-axis windows. Three-dimensional measures were performed offline using multiplanar reconstruction. The CSEPT space was smaller after CPB (p < 0.01). Before and after CPB, the midesophageal 5-chamber and long-axis windows were similar to each other, and both were larger than the pre-CPB 3D CSEPT distance. Patients with AS had smaller before and after CPB distances and areas compared with non-AS patients (p < 0.05). The change in CSEPT area in AS patients was 24%.

CONCLUSIONS

The CSEPT space is smaller after CPB and more so for patients with AS undergoing aortic valve replacement. Two-dimensional CEPT distances vary compared with 3D CSEPT distances. Additional study using Doppler analysis will elucidate the added value of 3D assessment of the CSEPT space.

Relationship Between Left Ventricular Geometry and Invasive Hemodynamics in Pediatric Pulmonary Hypertension

Background Ventricular septal flattening, frequently present in pulmonary hypertension (PH), can be quantified using eccentricity index (EI). EI has not been evaluated by concurrent echocardiography and cardiac catheterization and traditionally does not account for postsystolic septal flattening, often seen in PH. We evaluated left ventricular shape, including a novel measure of maximal EI to account for postsystolic septal flattening, to establish the relationship with concurrent invasive hemodynamics. Methods Echocardiography was performed at 2 institutions in 78 pediatric PH patients during cardiac catheterization and in 78 matched controls. From midpapillary parasternal short-axis views, EI and right-to-left ventricular diameter ratio were assessed. Results EI and right-to-left ventricular measures were significantly increased in PH compared with controls. Shape measures correlated with invasive hemodynamics and PH outcome measures (PH-related hospitalization, functional class, medical therapy escalation, and BNP [brain natriuretic peptide]). End-systolic EI of 1.16 best identified the presence of PH, whereas a maximal EI of 1.42 and 1.94 best identified half-systemic and systemic PH, respectively. A maximal EI of 1.27 was associated with an odds ratio of 16.16 (95% CI, 6.62-39.46) for PH-related hospitalization or escalation of therapy. Conclusions Using simultaneous echocardiography and catheterization in the largest study population to date, we demonstrate that EI and right-to-left ventricular ratio correlate with invasive hemodynamics and outcomes measures, and EI can accurately define those with clinically important PH. These measures strengthen the ability of echocardiography to identify and follow pediatric PH patients, especially in the absence of methods to quantify right ventricular systolic pressures.

Direct Visualization of the His Bundle Pacing Lead Placement by 3-Dimensional Electroanatomic Mapping: Technique, Anatomy, and Practical Considerations

BACKGROUND

His bundle pacing (HBP) remains technically challenging and is currently guided by electrograms and 2-dimensional fluoroscopy. Our objective was to describe a new technique for HBP directly guided by electroanatomic mapping (EAM).

METHODS

Twenty-eight patients were included. The atrioventricular septum was mapped via EAM, and His bundle (HB) electrograms, selective, and nonselective HB capture sites were tagged. Pacing leads were connected to EAM, navigated to tagged HB target sites and deployed. Intracardiac electrograms and pacing parameters were recorded. Lead location was tagged on the cloud of HB sites, which was divided into 3 arbitrary segments. In 5 patients, atrioventricular nodal ablation was performed with direct visualization of the HBP lead by EAM.

RESULTS

Reproducible navigation of the pacing lead to predetermined HBP locations guided by EAM was achieved in all patients. The lead was successfully deployed in 25 patients. HB cloud area was 360 (212) mm². There was no correlation between HBP threshold and lead location on the His cloud. The intracardiac electrograms atrial/ventricular ratio at the lead deployment site correlated with its EAM position on the His cloud ( P=0.045). Procedure, fluoroscopy, and mapping times were 116.0 (38.8), 8.6 (6.3), and 9.0 (11.4) minutes, respectively. HBP threshold at implant was 1.5 (2.3) V at 1.5 (1.0) ms. Distance between HB lead and ablation sites was 10.0 (1.3) mm in patients undergoing atrioventricular nodal ablation.

CONCLUSIONS

Direct guidance of HBP by EAM allows for direct visualization of the pacing lead on the HB cloud and reproducible navigation to predetermined HB capture sites. Intracardiac electrograms atrial/ventricular ratio at the lead deployment site correlates with His cloud location. EAM can be applied during standard HBP procedures or combined with atrioventricular nodal ablation.

Individualized Left Anterior Oblique Projection: A Highly Reliable Patient-Tailored Fluoroscopy Criterion for Right Ventricular Lead Positioning

BACKGROUND

Classical fluoroscopic criteria for the documentation of septal right ventricular (RV) lead positioning have poor accuracy. We sought to evaluate the individualized left anterior oblique (LAO) projection as a novel fluoroscopy criterion.

METHODS

Consecutive patients undergoing pacemaker or defibrillator implantation were prospectively included. RV lead positioning was assessed by fluoroscopy using posteroanterior, right anterior oblique 30° to rule out coronary sinus positioning, and LAO 40° in the classical group or individualized LAO in the individualized group. Individualized LAO was defined by the degree of LAO that allowed the perfect superposition of the RV apex (using the tip of the RV lead temporarily placed at the apex) and of the superior vena cava-inferior vena cava axis (materialized by a guidewire), hence providing a true profile view of the interventricular septum. Accuracy of fluoroscopy for RV lead positioning was then assessed by comparison with true RV lead positioning using transthoracic echocardiography.

RESULTS

We included 100 patients, 50 in each study group. Agreement between RV lead septal/free wall positioning in transthoracic echocardiography and fluoroscopy was excellent in the individualized group (k=0.91), whereas it was poor in the classical group (k=0.35). Septal/free wall RV lead positioning was correctly identified in 48/50 (96%) patients in the individualized group versus 38/50 (76%) in the classical group (P=0.004). For septal lead positioning, fluoroscopy had 100% Se and 89.5% Sp in the individualized group versus 91.4% Se and 40% Sp in the classical group. Complications and procedural data were comparable in both groups.

CONCLUSION

Individualized LAO is a quick and highly reliable patient-tailored fluoroscopy projection for RV lead positioning.

Essential Modifiers of Double Outlet Right Ventricle: Revisit With Endocardial Surface Images and 3-Dimensional Print Models

Hearts with double outlet right ventricle are a heterogeneous group of malformations in which a comprehensive diagnostic approach is required for tailored surgical management. This pictorial essay revisits essential modifiers of clinical and surgical importance in management of the patients with double outlet right ventricle using 3-dimensional volume-rendered endocardial surface images and 3-dimensional print models. Special emphasis is paid to the infundibular morphology, including the size and orientation of the outlet septum, relative to the margin of the ventricular septal defect, and the extent of the muscular infundibulum as an additional modifier of the distance between the ventricular septal defect margin and the arterial valve or valves.

Delayed diagnosis of traumatic ventricular septal perforation in penetrating chest injury: hematoma formation in the ventricular septum in CT suggests perforation

Background

Ventricular septal perforation (VSP) can be caused by a penetrating cardiac injury. Diagnosis of VSP tends to be delayed because a shunt might not be detected by color flow Doppler at an early stage following injury.

Case presentation

A 60‐year‐old man with depression was admitted to the emergency center after a knife injury in the chest. A focused assessment with sonography for trauma revealed cardiac tamponade. Shortly after an open cardiac massage and a pericardiotomy, his spontaneous circulation returned. At a later stage, follow‐up computed tomography, echocardiography, and left ventriculography showed traumatic ventricular septal perforation. Conservative therapy was chosen because the pulmonary blood flow/systemic blood flow ratio was 1.42.

Conclusion

The initial contrast computed tomography shows a septal hematoma. Its presence could be perceived as a perforation site in the interventricular septum.

The Fate of the Outflow Tract Septal Complex in Relation to the Classification of Ventricular Septal Defects

It is now established that the entity often described as an “aortopulmonary septal complex” is better considered as an “outflow tract septal complex”. This change is crucial for appropriate understanding of not only malformations of the outflow tract, but also ventricular septal defects. Thus, the embryonic outflow tract, as it develops, is separated into its two components by fusion of a protrusion from the dorsal wall of the aortic sac with the distal end of the outflow cushions. The key point with regard to morphogenesis is that, with ongoing development, these structures lose their septal integrity, although they can still be identified as septal structures when the ventricular septum itself is deficient. In the normal postnatal heart, however, the aortic and pulmonary components have their own walls throughout the length of the outflow tracts. All of this is of clinical significance, since some current concepts of categorisation of the ventricular septal defects are based on the existence in the normal heart of a “conal septum”, along with a “septum of the atrioventricular canal”. In this review, we show how analysis of postnatal hearts reveals the definitive ventricular septum to possess only muscular and fibrous components in the absence of either discrete outflow or inlet components. We also show that this information regarding development, in turn, is of major significance in determining whether categorisation of ventricular septal defects is best approached, in the first instance, on the basis of the borders of the defects or the fashion in which they open to the right ventricle.

Feasibility and Acute Hemodynamic Effect of Left Ventricular Septal Pacing by Transvenous Approach Through the Interventricular Septum

BACKGROUND

Left ventricular septal (LVS) pacing reduces ventricular dyssynchrony and improves cardiac function relative to right ventricular apex (RVA) pacing in animals. We aimed to establish permanent placement of an LVS pacing lead in patients using a transvenous approach through the interventricular septum.

METHODS AND RESULTS

Ten patients with sinus node dysfunction scheduled for dual-chamber pacemaker implantation were prospectively enrolled. A custom pacing lead with extended helix was introduced via the left subclavian vein and, after positioning against the right ventricular septum (RVS) using a preshaped guiding catheter, driven through the interventricular septum to the LVS. The acute hemodynamic effect of RVA, RVS, and LVS pacing was evaluated by invasive LVdP/dtmax measurements. The lead was successfully delivered to the LVS in all patients. Procedure time and fluoroscopy time shortened with experience. QRS duration was shorter during LVS pacing (144 ± 20 ms) than during RVA (172 ± 33 ms; P = 0.02 versus LVS) and RVS pacing (165 ± 17 ms; P = 0.004 versus LVS). RVA and RVS pacing reduced LVdP/dtmax compared with baseline atrial pacing (-7.1 ± 4.1% and -6.9 ± 4.3%, respectively), whereas LVS pacing maintained LVdP/dtmax at baseline level (1.0 ± 4.3%; P = 0.001 versus RVA and RVS). R-wave amplitude and pacing threshold were 12.2 ± 6.7 mV and 0.5 ± 0.2 V at implant and remained stable during 6-month follow-up without lead-related complications.

CONCLUSIONS

Permanent placement of an LVS pacing lead by transvenous approach through the interventricular septum is feasible in patients. LVS pacing preserves acute left ventricular pump function. This new pacing method could serve as an alternative and hemodynamically preferable approach for antibradycardia pacing.

The development of septation in the four-chambered heart

The past decades have seen immense progress in the understanding of cardiac development. Appreciation of precise details of cardiac anatomy, however, has yet to be fully translated into the more general understanding of the changing structure of the developing heart, particularly with regard to formation of the septal structures. In this review, using images obtained with episcopic microscopy together with scanning electron microscopy, we show that the newly acquired information concerning the anatomic changes occurring during separation of the cardiac chambers in the mouse is able to provide a basis for understanding the morphogenesis of septal defects in the human heart. It is now established that as part of the changes seen when the heart tube changes from a short linear structure to the looped arrangement presaging formation of the ventricles, new material is added at both its venous and arterial poles. The details of these early changes, however, are beyond the scope of our current review. It is during E10.5 in the mouse that the first anatomic features of septation are seen, with formation of the primary atrial septum. This muscular structure grows toward the cushions formed within the atrioventricular canal, carrying on its leading edge a mesenchymal cap. Its cranial attachment breaks down to form the secondary foramen by the time the mesenchymal cap has used with the atrioventricular endocardial cushions, the latter fusion obliterating the primary foramen. Then the cap, along with a mesenchymal protrusion that grows from the mediastinal mesenchyme, muscularizes to form the base of the definitive atrial septum, the primary septum itself forming the floor of the oval foramen. The cranial margin of the foramen is a fold between the attachments of the pulmonary veins to the left atrium and the roof of the right atrium. The apical muscular ventricular septum develops concomitant with the ballooning of the apical components from the inlet and outlet of the ventricular loop. Its apical part is initially trabeculated. The membranous part of the septum is derived from the rightward margins of the atrioventricular cushions, with the muscularizing proximal outflow cushions fusing with the muscular septum and becoming the subpulmonary infundibulum as the aorta is committed to the left ventricle. Perturbations of these processes explain well the phenotypic variants of deficient atrial and ventricular septation.

Late primary arterial switch for transposition of the great arteries with intact ventricular septum in an african population

The arterial switch operation (ASO) is the optimal management of transposition of the great arteries with intact ventricular septum (TGA-IVS) within the first 3 weeks of life; beyond this age optimal treatment is debatable. The authors adopted a strategy of primary ASO for TGA-IVS in the first 10 weeks of life regardless of left ventricular (LV) status. This report reviews the early outcomes with this management approach. Between August 2006 and December 2009, 22 patients with TGA-IVS underwent the primary ASO. Sixteen of them were less than 21 days old (early switch group) and 6 were between 31 and 66 days old (late switch group). A review of their hospital records was performed to determine outcomes in the 2 groups. Operative variables and postoperative outcomes were recorded. There was 1 hospital death in the early switch group (6.3%) but none in the late group (0%). Temporary mechanical circulatory support was required in 1 patient (6.3%) in the early switch group and in 2 of the 6 (33.3%) in the late switch group. One late death of undetermined cause occurred in the late switch group 8 weeks after discharge. No significant difference could be demonstrated between the 2 groups in terms of operative variables and the measured postoperative outcomes. It is concluded that the age limit for the primary ASO can be extended to at least 10 weeks; temporary mechanical circulatory support may be required as a rescue.

The insufficiency of left anterior oblique and the usefulness of right anterior oblique projection for correct localization of a computed tomography-verified right ventricular lead into the midseptum

BACKGROUND

The aim of the study was to verify the correct anchoring location for the tip of the right ventricular lead using cardiac computed tomography and to assess the best fluoroscopic and ECG criteria associated with the correct location of the electrode into the midseptum.

METHODS AND RESULTS

Patients indicated to pacemaker implantation were prospectively enrolled. The right ventricular lead was implanted into the midseptum according to standard criteria in left anterior oblique 40 view. The cardiac shadow on the right anterior oblique 30 was divided into 4 quadrants perpendicular to the lateral cardiac silhouette and the position of the lead tip was analyzed. The exact position of the lead tip was assessed using computed tomography. Of 51 patients, the right ventricular lead was anchored midseptum in 21 (41.2%; MS group). In 30 patients (58.8%; non-MS group), the lead was anchored in the adjacent anterior wall. The angle between the lead and horizontal axis on the left anterior oblique was similar in both groups. The non-MS group was associated with shorter distances between the tip and the cardiac contours in the right anterior oblique 30 (96.7% of leads in the non-MS group were in the outer quadrant versus 9.6% in the MS group; P<0.001). The presence of the lead in the middle or inferior quadrants was independently associated with correct midseptum placement with positive predictive value of 94.7%.

CONCLUSIONS

Despite the optimal shape of the left anterior oblique, substantial numbers of leads were not anchored in the midseptum. Knowing the right anterior oblique 30 lead position can ensure proper midseptal placement.

Three pledget technique for closure of muscular ventricular septal defects

We propose a modification of the simple, horizontal mattress, pledgetted suture technique for closing the small muscular ventricular septal defect (VSD) by interposing an oversized third pledget on the left ventricular (LV) aspect of the defect.

Simple targeted arterial rendering (STAR) technique: a novel and simple method to visualize the fetal cardiac outflow tracts

OBJECTIVE

To describe a novel and simple technique—simple targeted arterial rendering (STAR)—to visualize the fetal cardiac outflow tracts from dataset volumes obtained with spatiotemporal image correlation (STIC) and applying a new display technology (OmniView).

METHODS

We developed a technique to image the outflow tracts by drawing three dissecting lines through the four-chamber view of the heart contained in a STIC volume dataset. Each line generated the following plane: (a) Line 1: ventricular septum en face with both great vessels (pulmonary artery anterior to the aorta); (b) Line 2: pulmonary artery with continuation into the longitudinal view of the ductal arch; and (c) Line 3: long-axis view of the aorta arising from the left ventricle. The pattern formed by all three lines intersecting approximately through the crux of the heart resembles a star. The technique was then tested in 50 normal fetal hearts at 15.3–40.4 weeks' gestation. To determine whether the technique could identify planes that departed from the normal images, we tested the technique in four cases with proven congenital heart defects (ventricular septal defect (VSD), transposition of great vessels, tetralogy of Fallot and pulmonary atresia with intact ventricular septum).

RESULTS

The STAR technique was able to generate the intended planes in all 50 normal cases. In the abnormal cases, the STAR technique allowed identification of the VSD, demonstrated great vessel anomalies and displayed views that deviated from what was expected from the examination of normal hearts.

CONCLUSIONS

This novel and simple technique can be used to visualize the outflow tracts and ventricular septum en face in normal fetal hearts. Inability to obtain expected views or the appearance of abnormal views in the generated planes should raise the index of suspicion for congenital heart disease involving the great vessels and/or the ventricular septum. The STAR technique may simplify examination of the fetal heart and could reduce operator dependency.

Echocardiographic tissue characterization demonstrates differences in the left and right sides of the ventricular septum

The left and right ventricular function of the heart are influenced by the complex structure of the ventricular septum. The cyclic variation of ultrasonic backscatter over the cardiac cycle is known to be sensitive to both structural and functional characteristics of the myocardium. The objective of this study was to investigate differences in the measured magnitude and normalized delay of cyclic variation between the left and right sides of the ventricular septum in normal adult subjects (N = 31). The measured mean magnitudes of cyclic variation were found to be 4.9 ± 0.4 dB and 2.4 ± 0.3 dB (mean ± SE; p < 0.0001) and the corresponding normalized delay values were found to be 0.94 ± 0.05 and 1.59 ± 0.12 (mean ± SE; p < 0.0001) for the left and right sides, respectively. These results show significant differences in the measured magnitude and normalized delay of cyclic variation between the left and right sides of the ventricular septum in normal subjects that appear consistent with predictions based on previously described models of cyclic variation of backscatter and reported measurements of transmural differences in strain properties of the septum.