Morpho-functional assessment of interatrial septum: a transesophageal echocardiographic study

Characterization of the interatrial septum by high-field cardiac MRI: a comparison with multi-slice computed tomography

Background

Assessment of the interatrial septum (IAS) has become an attractive area of interest for a variety of important interventional procedures. Newer imaging modalities like multi-slice computed tomography (MSCT) and cardiac MRI (CMR) can provide higher resolution and wider field of view than echocardiography. Moreover, high-field (3-Tesla) CMR can even enhance spatial and temporal resolution.

The characteristics of the interatrial septum were retrospectively studied in 371 consecutive subjects (201 men, 31–73 years old) in whom MSCT was performed primarily for non-invasive evaluation of the coronary arteries. All subjects underwent both MSCT and MRI scans within 0–30 day’s interval. A 3D volume covering the whole heart was acquired across the heart with and without contrast enhancement. Also, patients underwent cardiac MSCT examinations using 64-row MSCT scanners.

Results

The mean scan time of MSCT was 10.4 ± 2.8 s and 9.7 ± 2.9 min for CMR. The mean length of IAS by CMR and CT was 39.65 ± 4.6 mm and 39.28 ± 4.7 mm, respectively. The mean maximal thickness of IAS by CMR and CT was 3.1 ± 0.97 mm and 3.15 ± 0.95 mm, respectively. The mean thickness of fossa ovalis by CMR and CT was 1.04 ± 0.36 mm and 1.04 ± 0.44 mm, respectively. The mean length of fossa ovalis by CMR and CT was 12.8 ± 3.7 mm and 12.8 ± 3.5 mm, respectively. Finally, the mean angle of IAS by CMR and CT was identical (155 ± 9.2°). Measurements of various morphological features of IAS showed no statistically significant difference between CMR and CT, with an excellent correlation and close relationship regarding IAS length, maximal IAS thickness, fossa ovalis thickness, fossa ovalis length, and IAS angle (r = 0.98, 0.98, 0.95, 0.96, and 0.92, respectively).

Conclusion

Whole-heart 3D acquisition at 3-T MRI using a free-breathing technique provides a valuable non-invasive imaging tool for excellent assessment of the interatrial septum—as compared to MSCT—that may have significant clinical implication for diagnostic purposes and therapeutic interventional procedures, as it may facilitate planning, improve outcome, and shorten its duration.

Measurement of interatrial septal thickness by echocardiography in patients with moderate to severe rheumatic mitral stenosis undergoing percutaneous balloon mitral valvuloplasty

Background

Longstanding severe rheumatic mitral stenosis (MS) is associated with changes in the atrial chamber dimensions. It is not known whether there is an increased thickness of the inter-atrial septum (IAS) in patients with severe rheumatic mitral stenosis. The objective of this study was to evaluate pre-procedural IAS thickness by echocardiography in patients with moderate to severe rheumatic mitral stenosis undergoing percutaneous balloon mitral valvuloplasty (PBMV).

Methods

The thickness of the IAS was measured by transesophageal echocardiography (TEE) in 86 patients between 14 and 65 years of age. Patients with moderate to severe rheumatic mitral stenosis undergoing percutaneous mitral balloon valvuloplasty (PMBV) at the National Institute of Cardiovascular Diseases (NICVD), Karachi were recruited for this study. IAS thickness was measured by TEE using standard views and 3 different phases of cardiac cycles were evaluated.

Results

Out of 86 patients, almost three fourths (73.3%) were between 14 and 29 years of age and two thirds (62.8%) were females. Mean IAS thickness was 2.56 (SD 0.92) mm at anterior region (AR), 1.89 (SD 0.75) mm at fossa ovalis (FO), and 2.95 (SD 0.97) mm at posterior region (PR). None of the demographic and clinical groups showed any statistically significant difference in IAS thickness.

Conclusions

Inter-atrial septum (IAS) thickness measurement does not change in the presence of moderate to severe rheumatic mitral stenosis as compared to the reported normal values of IAS thickness in cadaveric hearts.

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Understanding of the anatomy of atrial septum is important for the interventionist for safe and effective performance of trans-septal puncture.

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Echocardiography is the preferred imaging modality for evaluating the IAS.

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IAS thickness measurement by echocardiography provides a reasonable roadmap to guide transseptal puncture.

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IAS thickness measurement does not change in the presence of moderate to severe rheumatic mitral stenosis.

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A pre-procedural TEE may be sufficient for assessment of IAS thickness and anatomy relevant to the performance of transseptal procedures.

Transseptal puncture - Review of anatomy, techniques, complications and challenges

In recent years, the transseptal puncture approach has enabled passage of increasingly large and complex devices into the left atrium. Traditional tools remain effective in creating and dilating the initial puncture, with an acceptable safety profile. Even for skilled operators, the procedure is technically demanding and requires sound understanding of atrial anatomy. Intracardiac echocardiography is useful in cases of previous septal repair, poorly defined fossa ovalis anatomy or when considering patent foramen ovale portal crossing. Iatrogenic atrial septal defect (iASD) is the most commonly encountered long-term complication and there is increasing evidence that larger devices are leading to symptomatic defects. The size of the sheath crossing the septum is the strongest predictor of iASD formation but other factors such as longer procedure times, significant catheter manipulation and high pulmonary pressures also contribute. Transcatheter mitral valve repair involves the use of large 22 Fr catheters which carry alarmingly high rates of defect persistence with precipitation of symptoms and possible influence on mortality. Long-term follow up data, particularly beyond the 12-month period are lacking and resultantly, evidence to guide management is sparse. Refinements of conventional instruments, as well as innovations to puncture the septum without mechanical pressure, herald a progressively safer future for the transseptal technique.

Interatrial septal thickness is associated with the extent of left atrial complex fractionated atrial electrograms and acute procedural outcome in patients with persistent atrial fibrillation

AIMS

The interatrial septal thickness (IAST) reflects the changes of the atrial wall in patients with atrial fibrillation (AF). Complex fractionated atrial electrograms (CFAEs) were consistently positioned on the interatrial septum, especially in the remodelled left atrium (LA). We sought to characterize the relationship between IAST and LA CFAE area, as well as the acute procedural and clinical outcomes of catheter ablation in persistent AF patients.

METHODS AND RESULTS

This study included 71 patients who underwent catheter ablation for drug-refractory persistent AF. A stepwise ablation approach included circumferential pulmonary vein isolation followed by LA and right atrial CFAE-guided ablation. Interatrial septal thickness was measured 1 cm inferior to the fossa ovalis on cardiac computed tomography (CT). The extent of LA CFAEs was assessed by CFAE area and index (CFAE area/LA surface area × 100). Patients were grouped into tertiles according to the value of IAST. The mean IAST of the first, second, and third tertile was 4.69 ± 0.79, 6.44 ± 0.45, and 9.12 ± 1.42 mm, respectively (P < 0.001). The mean CFAE areas (5.6 ± 6.9, 18.5 ± 20.3, and 24.3 ± 26.6 mm(2), P = 0.005) and CFAE indexes (3.1 ± 4.2, 9.2 ± 10.7, and 11.8 ± 15.3, P = 0.025) in LA were significantly different among the three groups. More patients in the highest IAST tertile did not terminate AF during catheter ablation (12.5% vs. 26.1% vs. 37.5%, P = 0.048).

CONCLUSIONS

Interatrial septal thickness measured by cardiac CT is associated with the extent of CFAE area within the LA and is related to acute procedural success of catheter ablation. These findings suggest that IAST reflects the degree of atrial substrate and remodelling in patients with persistent AF.

Pathophysiology of paradoxical embolism: evaluation of the role of interatrial septum anatomy based on the intracardiac echocardiography assessment of patients with right-to-left shunting

BACKGROUND

Detailed anatomic variants of the interatrial septum in patients with right-to-left shunt and contribution of specific anatomies to the risk of ischaemic recurrences has not yet been comprehensively classified.

OBJECTIVE

To report a classification of the anatomic variants of the interatrial septum as observed by intracardiac echocardiography and its correlation with clinical and functional characteristics.

METHODS

We retrospectively reviewed the medical and instrumental data of 520 consecutive patients (mean age 44±15. 5 years, 355 women) who had over a 10-year period undergone intracardiac echocardiography and right-to-left shunt catheter-based closure. The four main features used to analyse were: (a) diameter of the oval fossa, (b) presence and length of the channel, (c) presence and degree of atrial septal aneurysm, and (d) rim thickness. The presence of Eustachian valve was also tabulated.

RESULTS

The combinations of interatrial septum anatomical features were classified into six main anatomical subgroups. Recurrent embolism, multiple ischaemic foci on brain magnetic resonance imaging, high grade shunt, and permanent shunt before transcatheter closure procedure were associated with type 2, type 4, and type 6. Type 4 anatomical subtype (OR 4.1, 1.5-8 [95% CI], p<0.001) and type 2+presence of Eustachian valve (OR 4.3, 1.6-9 [95% CI], p<0.001) were the strongest predictors of recurrent ischaemic events before transcatheter closure.

CONCLUSION

Our study showed that interatrial septum anatomy greatly differs among patients with right-to-left shunt, as well as the risk of ischaemic recurrences in different anatomies.

Usefulness of intracardiac echocardiography with a mechanical probe for catheter-based interventions: a 10-year prospective registry

BACKGROUND

The clinical outcome benefit of intracardiac echocardiography (ICE) with a mechanical probe during congenital heart disease interventions has not been fully investigated. We reported the long-term results of a prospective registry of interatrial shunt closure guided by mechanical ICE.

METHODS

We enrolled 537 patients (mean age 48 ± 19.0 years, 378 females) submitted to ICE-aided procedures in a prospective registry over a 10-year period (September 2003-September 2013). All patients underwent transesophageal echocardiography (TEE) before the planned procedure. We evaluated (1) structure identification capability, (2) fossa ovale and interatrial septum component measurement, (3) procedure monitoring capability, (4) procedural and fluoroscopy times, and radiograph dose, (5) probe-related complications.

RESULTS

ICE was successfully performed and was able to correctly identify the structures previously assessed by TEE in all patients. In 24 patients (4.5%), ICE allowed better anatomy definition than TEE. In 35 other patients (6.5%), ICE identified structures not observed by TEE, which led to change indications to interventions or the operative technique to be used. In 131 patients (24.4%), ICE evaluation led to change the planned device to be implanted. There was only one probe-related complication (0.2%).

CONCLUSIONS

Mechanical ICE may offer a valid alternative to conventional TEE in guiding congenital heart disease interventional procedures.

Patent foramen ovale: a comprehensive review for pulmonologists

PURPOSE OF REVIEW

A comprehensive review of the main concepts about patent foramen ovale (PFO) management is offered.

RECENT FINDINGS

PFO is a common, usually benign, anatomical variant that in the presence of a discrete right-to-left shunt and other predisposing factors (Eustachian valve/Chiari network, atrial septal aneurysm, and coagulation cascade abnormalities) may play an important role in the patho-physiology of paradoxical embolism at different levels (cryptogenic stroke, peripheral embolism, coronary embolism, etc.). Therapy is a controversial issue, since data on these patients are variable and accepted guidelines are missing. Recurrent strokes are the most diffuse and accepted indication for transcatheter closure of PFO, but severe refractory migraine with aura, unexplained oxygen desaturation, orthodeoxia-platypnea, and other conditions have been suggested to benefit from PFO closure. Different devices and techniques have been proposed for this procedure, mainly depending on operator experience and preferences, which have contributed to this intervention becoming a well tolerated and effective procedure with very low morbidity and virtually absent mortality.

SUMMARY

PFO management is still a debated field: indications, pathophysiology and ideal closure techniques remain to be fully clarified and investigated before considering PFO closure a routine procedure.

Transcatheter patent foramen ovale closure in spite of interatrial septum hypertrophy or lipomatosis: a case series

OBJECTIVE

Hypertrophy and lipomatosis of the interatrial septum have been thought to be contraindications for transcatheter patent foramen ovale (PFO) and atrial septal defect closure because of the limits of current devices and the risk of suboptimal results. No reports have been produced yet about PFO closure in patients with such conditions. We retrospectively assessed the safety and effectiveness of PFO closure in patients with hypertrophy or lipomatosis of fossa ovalis rims.

METHODS

We searched our database of 140 consecutive patients (mean age 43 +/- 15. 5 years, 98 female patients) who underwent transcatheter PFO closure for cases of hypertrophy or lipomatosis of the interatrial septum. All patients were screened with transesophageal echocardiography before the operation. All patients underwent intracardiac echocardiography study and attempted closure.

RESULTS

Ten patients (7.1%) underwent an attempt at transcatheter closure in the presence of hypertrophy of the rims (eight patients) or lipomatosis (two patients). All patients were aged more than 50 years and has multiple recurrent stroke events (nine patients) or need for a posterior cerebral surgical procedure (one patient) making closure mandatory. After intracardiac echocardiography study and measurements, two 25 mm Amplatzer and eight 25 mm Premere Occlusion System devices have been implanted successfully. On mean follow-up of 36.6 +/- 14.8 months, two patients had a small residual shunt: no recurrence of stroke or aortic erosion or device thrombosis was observed during this period.

CONCLUSION

Transcatheter PFO closure in the presence of hypertrophy or lipomatosis of fossa ovalis rims is not contraindicated per se: careful evaluation of rim thickness with intracardiac echocardiography and selection of soft and asymmetrically opening devices may allow for a safe and effective PFO closure, at least in patients with no severe atrial septal aneurysm.

Clinical, laboratory, and transesophageal echocardiographic correlates of interatrial septal thickness: a population-based transesophageal echocardiographic study

BACKGROUND

The determinants of interatrial septal (IAS) thickening ("lipomatous hypertrophy"), a common echocardiographic finding in the elderly, are poorly defined. The objective of this study was to determine the clinical, laboratory, and transesophageal echocardiographic correlates of IAS thickening in the general population.

METHODS

The thickness of the IAS was measured by transesophageal echocardiography in 384 patients (median age: 66 years; range: 51-101 years; 53% men) participating in a population-based study (Stroke Prevention: Assessment of Risk in a Community). The associations between atherosclerosis risk factors, clinical cardiovascular disease, aortic atherosclerotic plaques, and IAS thickness were examined.

RESULTS

Age and body surface area (BSA) were significantly associated with IAS thickness (median: 6 mm; range: 2-17 mm). IAS thickness increased by 12.6% per 10 years of age (95% confidence interval: 9.0-16.4%) adjusting for sex and BSA, and increased by 7.0% per 0.1 m 2 BSA (confidence interval: 5.0-9.2%) adjusting for age and sex. Overall, age, sex, and BSA accounted for 22.5% of the variability in IAS thickness. Current smoking (20.4% increase in IAS thickness in current smokers) and hypertension treatment (8.5% increase in treated patients) were associated with increased IAS thickness, adjusting for age, sex, and BSA ( P < .05), but these two risk factor variables jointly explained only an additional 2.3% of the variability in IAS thickness beyond the variability explained by age, sex, and BSA. Clinical coronary artery and cerebrovascular disease, atrial arrhythmias, and aortic atherosclerotic plaques were not associated with IAS thickness, adjusting for age, sex, and BSA ( P > .3).

CONCLUSIONS

IAS thickening is an age-associated process. Atherosclerosis risk factors are weakly associated with IAS thickening, whereas atherosclerotic vascular disease is not.

The Importance of Increased Interatrial Septal Thickness in Patients with Atrial Fibrillation: A Transesophageal Echocardiographic Study

BACKGROUND

Histological studies in animal models have showed that extensive atrial fibrosis or fatty deposition as a result of loss of atrial cardiomyocytes increases the propensity to develop atrial fibrillation (AF). Although several reports have suggested that AF in humans may be a consequence of these mechanisms, no study has correlated the presence of AF with interatrial septal thickness (IAST).

METHODS

Accordingly, we conducted a prospective analysis in 150 consecutive patients referred for transesophageal echocardiography (TEE) for numerous medical reasons. A total of 105 patients (mean age 62 +/- 14 years) who met inclusion and exclusion criteria were included for analysis. Pertinent demographics, echocardiographic chamber dimensions, left ventricular ejection fraction (LVEF), color flow, and spectral Doppler analysis, as well as IAST measured in both systole (S) and diastole (D) were obtained.

RESULTS

When patients with a documented history of AF were compared to patients without documented AF, no statistical difference was noted in terms of patients' height, weight, IVS thickness, or LVEF. Patients with AF had a significantly larger left and right atrial dimensions (P < 0.001), lower left atrial appendage emptying velocities (P < 0.002), and pulmonary vein systolic Doppler signal (P < 0.01). The IAST in systole in patients with AF was 0.75 +/- 0.27 cm versus 0.60 +/- 0.16 cm in patients without AF (P < 0.006) while the IAST in diastole was 0.61 +/- 0.22 cm versus 0.49 +/- 0.12 cm, respectively (P < 0.009). However, no statistical difference was noted between IAST in either systole (P < 0.8) or diastole (P < 0.8) among patients with AF based on the duration of this arrhythmia.

CONCLUSIONS

The results of this prospective TEE study show a statistically significant increase in IAST with the presence of AF independent of patient's age, height, weight, and the degree of IVS thickness. In addition, since no significant valvular abnormalities or compromise in left ventricular systolic function were present, the increase in IAST in patients with AF then suggest possible changes in the material properties of the atrial wall, easily identified by TEE on the interatrial septum, either as a cause or as a result of AF. Since no correlation was found between the degree of IAST and the duration of AF, the presence of IAST not only might identify patients with a higher propensity to have or develop this atrial arrhythmia; but also be a surrogate marker of changes within the components of the atrial wall in AF.