Jakub Hołda

Influence of different fixation protocols on the preservation and dimensions of cardiac tissue

Recent extensive progress in invasive cardiac procedures has triggered a wave of dozens of heart morphometric anatomical studies that are carried out largely using autopsied samples fixed in formaldehyde solution prior to observations and measurements. In reality, very little is known about changes in heart tissue dimensions during fixation. The aim of this study was therefore to investigate how fixation affects the dimensions of cardiac tissue, and if different types and concentrations of reagents affect this phenomenon. A total of 40 pig heart samples were investigated, and seven different measuring sites were permanently marked in every heart prior to fixation. Four study groups (n = 10 each) were assembled that differed only in concentration and the type of fixative: (i) 2% formaldehyde solution; (ii) 4% formaldehyde solution (formalin); (iii) 10% formaldehyde solution; (iv) alcoholic formalin. The samples were measured before and after fixation at the following time points: 24 h, 72 h and 168 h. It was found that different fixatives significantly affected different parameters. Almost all of the heart dimensions that were measured stabilized after 24 h; later changes were statistically insignificant in the point‐to‐point comparison. Change in the length of the interatrial septum surface was not altered significantly in any of the fixatives after 24 h of preservation. It was found that 10% formaldehyde increased the thickness of muscular tissue only after 24 h; this thickening was reduced after 72 h and was insignificant at 168 h. Other heart parameters in this group do not present significant changes over the entire fixation time duration. In conclusion, the 10% formaldehyde phosphate‐buffered solution appeared to be the best fixative among the fixatives that were studied for cardiac morphometric purposes; this solution caused the smallest changes in tissue dimensions. Measurements should be obtained at least after 1 week of preservation when most parameters exhibit the smallest changes compared with the non‐preserved samples.

Atrial septal pouch — Morphological features and clinical considerations

BACKGROUND The atrial septal pouch (SP) is a new anatomical entity within the interatrial septum. The left-sided SP may be the source of thrombus and contribute to ischemic stroke. The aim of this study was to provide a detailed morphometric description of the SP. METHODS Two hundred autopsied hearts (23% deriving from females) with a mean age of 46.7±19.1years were investigated. We assessed the morphology of the interatrial septum. We obtained measurements and casts of the SPs, and we conducted histological staining of the left-sided SPs. RESULTS Patent foramen ovale was observed in 25% of hearts. We found a left SP in 41.5%, right in 5.5% and a double SP in 5.5% of hearts. We found the patent foramen ovale (PFO) more often in younger hearts, and the SP and smooth septum were more prevalently found in older hearts (p=.0023). The mean volume of the left-sided SP was 0.31±0.11ml, which represented 13.6±9.4% (range: 3.1-44.9%) of the left atrial appendage volume. The SP shape resembled a cone or a cylinder with some smaller diverticula originating from the main body. The SP free wall was composed of two layers of endocardium, transverse muscle fibers and connective tissue. CONCLUSIONS A left-sided SP was present in 47% of individuals. The SP arises as a result of PFO channel closure. The anatomy of left-sided SP may promote blood stasis and thrombus formation. The universal formula for SP volume was calculated.

Normal distal pulmonary vein anatomy

Background. It is well known that the pulmonary veins (PVs), especially their myocardial sleeves play a critical role in the initiation and maintenance of atrial fibrillation. Understanding the PV anatomy is crucial for the safety and efficacy of all procedures performed on PVs. The aim of this study was to present normal distal PV anatomy and to create a juxtaposition of all PV ostium variants. Methods. A total of 130 randomly selected autopsied adult human hearts (Caucasian) were examined. The number of PVs ostia was evaluated and their diameter was measured. The ostium-to-last-tributary distance and macroscopic presence of myocardial sleeves were also evaluated. Results. Five hundred forty-one PV ostia were identified. Four classical PV ostia patterns (two left and two right PVs) were observed in 70.8% of all cases. The most common variant was the classical pattern with additional middle right PV (19.2%), followed by the common ostium for the left superior and the inferior PVs (4.44%). Mean diameters of PV ostia (for the classical pattern) were: left superior = 13.8 ± 2.9 mm; left inferior = 13.3 ± 3.4 mm; right superior = 14.3 ± 2.9 mm; right inferior = 13.7 ± 3.3 mm. When present, the additional middle right PV ostium had the smallest PV ostium diameter in the heart (8.2 ± 4.1 mm). The mean ostium-to-last-tributary (closest to the atrium) distances were: left superior = 15.1 ± 4.6 mm; left inferior = 13.5 ± 4.0 mm; right superior = 11.8 ± 4.0 mm; right inferior = 11.0 ± 3.7 mm. There were no statistically significant differences between sexes in ostia diameters and ostium-to-last-tributary distances. Conclusion. Only 71% of the cases have four standard pulmonary veins. The middle right pulmonary vein is present in almost 20% of patients. Presented data can provide useful information for the clinicians during interventional procedures or radiologic examinations of PVs.

Clinical Anatomy of the Cavotricuspid Isthmus and Terminal Crest

The aim of this study was to provide useful information about the cavotricuspid isthmus (CTI) and surrounding areas morphology, which may help to plan CTI radio-frequency ablation. We examined 140 autopsied human hearts from Caucasian individuals of both sexes (29.3% females) with a mean age of 49.1±17.2 years. We macroscopically investigated the lower part of the right atrium, the CTI, the inferior vena cava ostium and the terminal crest. The paraseptal isthmus (18.5±4.0 mm) was significantly shorter than the central isthmus (p<0.0001), and the central isthmus (24.0±4.2 mm) was significantly shorter than the inferolateral isthmus (29.3±4.9 mm) (p<0.0001). Heart weight was positively correlated with all isthmus diameters. Three different sectors of CTI were distinguished: anterior, middle and posterior. The middle sector of the CTI presented a different morphology: trabeculae (N = 87; 62.1%), intertrabecular recesses (N = 35; 25.0%) and trabecular bridges (N = 18; 12.9%). A single sub-Eustachian recess was present in 48.6% of hearts (N = 68), and a double recess was present in 2.9% of hearts (N = 4) with mean depth = 5.6±1.8mm and diameter = 7.1±3.4mm. The morphology of the distal terminal crest was varied; 10 patterns of the distal terminal crest ramifications were noted. There were no statistically significant differences in any of the investigated CTI parameters between groups with different types of terminal crest ramifications. The presence of intertrabecular recesses (25.0%), trabecular bridges (12.9%) and sub-Eustachian recesses (48.6%) within the CTI can make ablation more difficult. We have presented the macroscopic patterns of final ramifications of the terminal crest within the quadrilateral CTI area.

Anatomic characteristics of the mitral isthmus region: The left atrial appendage isthmus as a possible ablation target

The mitral isthmus is a part of the postero-inferior area of the lateral left atrial wall located between the mitral annulus and the left inferior pulmonary vein ostium. Linear ablation lesions are created within the mitral isthmus for the invasive treatment of left atrial arrhythmias. However, the anatomy of this region is not fully understood. The aim of this study has been to provide a detailed morphometric description of the mitral isthmus region and to propose another possible isthmus within the investigated heart area that may serve as a potential new ablation target. Two hundred autopsied, non-atrial fibrillation hearts (23.5% deriving from females) whose donors were a mean of 47.6±17.6years old were investigated. We macroscopically assessed the anatomy of the postero-inferior area of the lateral left atrial wall. The mean mitral isthmus length was 28.8±7.0mm and was significantly longer than the left atrial appendage (LAA) isthmus (14.2±4.8mm) (p=.00). The distance between the LAA orifice and the left inferior pulmonary vein ostium (18.4±4.8mm) was longer than the LAA isthmus (p=.00) and shorter than the mitral isthmus (p=.00). The LAA isthmus was longer in hearts with a common left pulmonary vein (p=.037). In 65.5% of all cases the area between the right and left mitral isthmus lines was completely smooth. In the remaining hearts, crevices and diverticula (18.0%), intertrabecular recesses (7.0%), trabecular bridges (3.5%), or co-existence of these structures (6%) could be observed. The LAA isthmus line was smooth in 95.5% of all cases, with only small crevices in the remaining 4.5%. In conclusion, regardless of the anatomical variants of the left-sided pulmonary veins, the mitral isthmus area is quite uniform in size. The LAA isthmus is considerably shorter than the mitral isthmus. The mitral isthmus line has many unwanted structures that may entrap the catheter, which is not the case for the LAA isthmus. We proposed the LAA isthmus line for potential clinical use.

Spatial relationship of blood vessels within the mitral isthmus line

Aims The aim of this study was to assess the spatial relationship of blood vessels and the thickness of the atrial wall within the mitral isthmus line. Methods and results A total of 200 randomly selected autopsied adult human hearts (Caucasian) were examined. The mitral isthmus line was cut longitudinally and the thickness of the left atrial wall was measured. The blood vessels within the isthmus were identified and their relationship with the endocardial surface (ES), mitral annulus (MA), and the left inferior pulmonary vein (LIPV) ostium was assessed. The mean myocardial thickness in the upper, middle, and lower 1/3 of the mitral isthmus section were 1.9 ± 1.0, 3.0 ± 1.5, and 2.7 ± 1.3 mm, respectively. The great cardiac vein (GCV) was present within the isthmus in 98.0%, the left circumflex artery (LCx) in 57.0%, and the Marshall vein in 35.0% of all hearts. The GCV was located 4.5 ± 2.2 mm from the ES, 7.3 ± 5.3 mm from the MA, and 24.3 ± 7.3 mm from the LIPV. The LCx was situated 3.8 ± 2.3 mm from the ES, 7.9 ± 5.1 mm from the MA, and 25.3 ± 8.0 mm from the LIPV. We were able to detect eight different patterns of GCV and LCx mutual arrangement within the mitral isthmus line. Conclusion The myocardium is the thinnest in the upper 1/3 sector, and the blood vessels are mainly located in the middle and lower 1/3. In 49.1%, the LCx is situated at a distance of less than 3 mm from the ES. In 55.3%, the LCx is located between the GCV and ES of the left atrium.

Mid-esophageal bicaval versus short-axis view of interatrial septum in two-dimensional transesophageal echocardiography for diagnosis and measurement of atrial septal pouches

Recent studies suggest that the left‐sided septal pouch (SP) may increase the risk of cryptogenic stroke and act as an arrhythmogenic substrate. The aim of this study was to compare two transesophageal echocardiography (TEE) projections of the interventricular septum: mid‐esophageal bicaval and short‐axis views toward evaluating their ability to detect SPs.

Geometry of Koch's triangle

Aims The first aim of this study was to determine the size of the Kochs triangle. The second one was to investigate relation between its dimensions and other individual-specific and heart-specific parameters as well as to create universal formula to estimate triangle dimensions based on these parameters. Methods and results This study is a prospective one, presenting 120 randomly selected autopsied hearts dissected from adult humans (Caucasian) of both sexes (31.7% females), with mean age of 49.3 ± 17.4 years. The length of triangle sides and angles were measured and the triangle area was calculated as well. Sixteen additional heart parameters were measured in order to analyse potential relationship between the dimensions of Kochs triangle and other dimensions of the heart, using linear regression analysis. The mean (±SD) length of the anterior edge was approximated to 18.0 ± 3.8 mm, the posterior edge to 20.3 ± 4.3 mm, and the basal edge to 18.5 ± 4.0 mm. The average values of the apex angle, the Eustachian angle, and the septal leaflet angle were 58.0 ± 14.4°, 53.8 ± 10.6°, and 67.6 ± 14.4°, respectively. The mean value of the Kochs triangle area was 151.5 ± 55.8 mm2. The 95th percentile of triangles height (the distance from the apex to the coronary sinus) was 21.8 mm. Conclusion Mean values and proportions of triangles sides and angles were presented. Kochs triangle showed considerable individual variations in size. The dimensions of the triangle were strongly independent from individual-specific and heart-specific morphometric parameters; however, the maximum triangles height can be estimated as 22 mm.

Left-Sided Atrial Septal Pouch is a Risk Factor for Cryptogenic Stroke

Background: The atrial septal pouch is an anatomic variant of the interatrial septum. The morphology of the left‐sided septal pouch (LSSP) may favor blood stasis and predispose to thromboembolic events. The aim of this study was to determine the association between LSSP presence and cryptogenic stroke. Methods: A total of 126 consecutive patients with cryptogenic stroke and 137 age‐matched control patients without stroke were analyzed retrospectively. The presence and dimensions of LSSPs were assessed using transesophageal echocardiography. Results: LSSP was present in 55.6% of patients with cryptogenic stroke and in 40.9% of those without stroke (P = .02). In univariate analysis, patients with LSSP were more likely to have cryptogenic stroke (odds ratio, 1.81; 95% CI, 1.11–2.95; P = .02). After adjusting for other risk factors using multiple logistic regression, the presence of an LSSP was found to be associated with an increased risk for cryptogenic stroke (odds ratio, 2.02; 95% CI, 1.19–3.41; P = .01). There were no statistically significant differences in size of the LSSP between patients with and those without stroke (P > .05). Conclusions: There is an association between the presence of an LSSP and an increased risk for cryptogenic stroke. More attention should be paid to clinical evaluations of LSSPs. HighlightsThe authors demonstrate an association between the presence of LSSP and cryptogenic stroke.In patients with cryptogenic stroke, LSSP should be considered a possible site of thrombus formation.Large prospective trials are necessary to determine role of LSSP as an independent stroke risk factor.

Blood Vessels and Myocardial Thickness within the Left Atrial Appendage Isthmus Line: Blood Vessels and Myocardium in the LAA Isthmus

Electric isolation of the left atrial appendage (LAA) and linear ablations in the area of the LAA base are gaining popularity. However, very little is known about the myocardial architecture and the presence of epicardial blood vessels within this region, which could significantly influence the course of such procedures. We examined 200 autopsied hearts (22.5% females, 46.7 ± 16.8 years old). The LAA isthmus (i.e., the line between the LAA ostium and the mitral annulus) was cut longitudinally. The myocardium was thickest at the LAA end of the isthmus (2.4 ± 0.7 mm) followed by its middle sector (2.1 ± 0.7 mm) inside the LAA, 5 mm from its ostium (1.9 ± 0.7 mm), and the mitral annulus end of the isthmus (1.8 ± 0.6 mm) (P < 0.0001). At least one artery was found in 96.5% of all samples (89.5% were single branched, 7% had two branches). The great cardiac vein was found in 77.0% and the left marginal vein in 2.5%. The artery was interposed between the endocardium and the great cardiac vein in 31.5% of cases. The smallest distance between the endocardium and the artery was 0.5 mm and between the endocardium and the vein was 0.7 mm. In total, we were able to distinguish fifteen different types of vascular arrangements within the LAA isthmus line in this study. The myocardium within the LAA isthmus is thickest at its LAA end. The left circumflex coronary artery branches are the most frequently‐occurring vessels within the isthmus and are present in almost all cases, while the great cardiac vein is present in three quarters of hearts. Clin. Anat. 31:1024–1030, 2018.