Clinical anatomy of the coronary venous system and relevance to retrograde cardioplegia and cardiac electrophysiological interventions

Anomalies of coronary venous system, the valve of the coronary sinus (Thebesian valve) and other cardiac malformations may make interventions through the coronary sinus difficult. These variants may pose a challenge in cannulating the coronary sinus for retrograde cardioplegia and for interventions performed through the coronary sinus by cardiac electrophysiologist/interventional cardiologist. Retrograde cardioplegia is an established method of myocardial protection with advantages, indications, and complications. A good knowledge of the anatomy of the coronary sinus and its variants is important in understanding the difficulties encountered while cannulating the coronary sinus for the delivery of retrograde cardioplegia, cardiac resynchronization therapy, treatment of arrhythmias, and percutaneous mitral valve annuloplasty.

Morphological Study of the Thebesian Valve in Fresh Autopsied Adult Human Hearts

Background The coronary sinus (CS) and its tributaries have been used to perform various electrophysiological and cardiac interventional procedures which require cannulation. The Thebesian valve (TV) guarding the coronary sinus orifice (CSO) exhibits morphological variations which might make cannulation unsuccessful leading to the failure of invasive cardiac procedures. This study aimed to analyze in detail the morphological features of the TV in fresh autopsied human hearts which were representative of the adult population of this region owing to its practical implications in invasive cardiac procedures. Methodology This was a cross-sectional, descriptive study conducted in the Department of Anatomy in collaboration with the Department of Forensic Medicine and Toxicology at Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry. A total of 104 fresh adult heart specimens were collected during the autopsy. The CSO was located, and the characteristic shape, composition, position, and extent of coverage of the CSO by the TV were observed and analyzed. Results The TV was present in 65% of heart specimens. The most common shape was remnant (33%), and the most common site of origin was inferior (63%). The valve composition was thin and membranous in 63% of heart specimens. In 7% of heart specimens, the TV covered more than 75% of the CSO diameter, of which in 4% of heart specimens, the CSO was completely closed and found to be obstructive. Conclusions This study highlights the variability in the morphological structure of the TV in adult human hearts and its potential implications in unsuccessful CS cannulation and failure of invasive cardiac procedures. Thus, prior imaging of the TV should be an integral part of CS cannulation procedures to avoid unsuccessful cannulation and complications related to repeated forceful cannulation.

Peculiarities in coronary sinus anatomy: implications for successful cannulation from an autoptic study

Aims

The number of cardiovascular procedures using the coronary sinus (CS) as a gateway is constantly increasing. The present study aimed to define specific structures within CS, which could potentially complicate CS cannulation and to develop a new Thebesian valve (TV) classification system.

Methods and results

The study was performed on 560 consecutive unfixed cadaveric hearts during routine autopsy examination (1–3 days post-mortem). Basic CS dimensions were measured and the presence and dimensions of the TV and the Vieussens valve (VV) were assessed. Thebesian valves were classified according to their morphology into six main types: remnant fold, semilunar, fenestrated, chord, fused strands, and mixed shaped. The median age of hearts was 48 years (range 16–95 years), and 38.9% were female. Thebesian valve was present in 79.5%. The most common TV type was semilunar (54%) followed by fenestrated (8.2%), remnant fold (5.5%), fused strands (4.8%), chord (4.0%), and mixed shaped (3.0%). In 1.1% of hearts, TV totally covered the coronary sinus ostium (CSO). The VV was detected in 67.9%. Potentially occlusive VV was found in 1.1% hearts and in all of which it coexisted with obstructive TV. The median CSO area was 87.9 mm² [interquartile range (IQR): 56.5–127.1 mm²] and median CS length was 38 mm (IQR: 29.5–45 mm). The CSO area and CS length correlated with each other and with the right atrium’s dimensions.

Conclusion

We identified six types of TVs, among which only 1.1% TVs caused total occlusion of CSO. The obstructive TV co-existed with potentially occlusive VV what might hinder CS cannulation.

The Thebesian valve and coronary sinus in cardiac magnetic resonance

Purpose

There is no complex research exploring usefulness of cardiac magnetic resonance in the evaluation of the coronary sinus including Thebesian valve, which can be useful before selected electrophysiology procedures.

Methods

One hundred twenty-two patients aged 49.2 ± 17.2 (42 women) were included in the study; 4 of them were excluded. A steady-state free-precession (SSFP) sequence was the basis of the visualization and analysis of the coronary sinus as well as Thebesian valve. In selected cases, dedicated coronary sinus sequences were created. All data were evaluated by experienced cardiac magnetic resonance investigators.

Results

We were able to visualize the coronary sinus by using basic SSFP sequence in all patients, however in four cases in suboptimal quality. Average length of the coronary sinus was 39.73 ± 16.9 mm, average diameter was 9.81 ± 9.3 mm, and average angle of the entrance of the coronary sinus into the right atrium was 111.37 ± 13.8°. The Thebesian valve as the gate of the coronary sinus was found in 56 cases (45.9 %). In 21 patients (17.2 % of all), the valve was porous or almost totally covered the coronary sinus ostium, which can potentially create problems during CS cannulation.

Conclusions

In most of the cases, it is possible to visualize and measure the coronary sinus using cardiac magnetic resonance with SSFP sequence. In selected cases, it is necessary to perform additional dedicated short sequences. Thebesian valve was visualized in almost 50 % of patients.

Anatomical variations of the coronary sinus valve (Thebesian valve): implications for electrocardiological procedures

AIMS

The Thebesian valve (TV) can be a significant obstacle to coronary sinus (CS) cannulation. The aim of this study was to evaluate the characteristic features of the CS valve--TV anatomy. In particular, emphasis was placed on identifying specific structures of the TV that could potentially complicate CS cannulation.

METHODS AND RESULTS

We examined 273 autopsied human hearts. The height of the TV and the diameter of the CS were measured. The valves were classified according to their shape into five types: remnant, semilunar, fold, cord, and mesh and fenestrated. The mean transverse CS ostium (CSO) diameter was 12.2 ± 3.5 mm. The TV was present in 224 (82.1%) cases. The most common type of TV was semilunar: 32.6%; followed by remnant: 25.5%; fold: 17.4%; cord: 14.3%; and lastly mesh and fenestrated: 10.3%. The mean TV height for remnant-semilunar-fold types was 5.8 ± 3.0 mm. In seven cases, the present TV (2.6%) covered the entire orifice of the CS. Hearts with larger CSO diameter had lower TV height (P < 0.001).

CONCLUSIONS

We propose a new classification of the TV shapes based on the largest sample to date. We assessed that only in 2.6% of all 273 cases the presence of an obstructive TV can cause unsuccessful cannulation. The height of the TV was inversely correlated to the CSO diameter (r = -0.33; P < 0.001).

Variance in coronary venous anatomy: a critical determinant in optimal candidate selection for cardiac resynchronization therapy

BACKGROUND

Knowledge of coronary sinus (CS) anatomy and its variations is one of the important factors determining the final position of left ventricle pacing lead during cardiac resynchronization therapy.

METHODS

Coronary venous system anatomy, including number, diameter, and opening angles of tributaries, was studied in 50 normal formalin-fixed adult cadaveric hearts.

RESULTS

Thebesian valve (TV) and Vieussens valve were present in 64% and 60% cases, respectively. CS ostium coverage of ≥75% by TV was seen in 25% (8/32) cases. Number of prominent tributaries lying between anterior interventricular vein and middle cardiac vein varied from 1-4. In 28% of hearts, only one prominent tributary was present. Midlateral vein (average diameter 1.75 ± 0.66 mm) with an average distance of 43.5 ± 12.2 mm from coronary ostium was present in 58% (29/50) hearts, of which it formed an acute angle with CS axis in four (13.39%) cases. Posterolateral vein (average diameter 1.62 ± 0.45 mm) with an average distance of 33.4 ± 11.7 mm from coronary ostium was found in 72% (36/50) cases and formed an acute angle with CS in three (8.33%) cases.

CONCLUSIONS

Restrictive TV covering ≥75% CS ostium (25% cases), presence of single prominent tributary (28% cases), and formation of acute angle of tributary with CS axis (1/4 cases with anterolateral vein, 4/29 cases with midlateral vein, 3/36 cases with posterolateral vein, and 3/28 cases with posterior veins of the left ventricle) can impede successful cannulation of CS.

Anatomy of the coronary sinus and epicardial coronary venous system in 620 hearts: an electrophysiology perspective

INTRODUCTION

Cannulation of the coronary sinus (CS) is a prerequisite for left ventricular (LV) pacing and certain ablation procedures. The detailed regional anatomy for the coronary veins and potential anatomic causes for difficulty with these procedures has not been established.

METHODS AND RESULTS

Therefore, we performed macroscopic measurements in 620 autopsied hearts (mean age 60 ± 23 years, 44% female). The CS was preserved for analysis in 96%. Sixty-three percent had a Thebesian valve that covered the posterior aspect of the CS ostium with extension to the superior (50%) and inferior aspects (18%) and was obstructive with fenestrations in 3 specimens. Partial or near occlusive valves were present occasionally at the ostium of the great cardiac vein (Vieussens; 8%) and middle cardiac vein (5%). Ninety-three percent had left atrial branches, and 41% had at least one branch with lumen > 3 French. For CRT lead placement, the mid-lateral LV was accessible from the middle cardiac vein (20%), the left posterior vein (92%) or the anterior interventricular vein (86%). Among specimens where the left phrenic nerve was preserved it crossed the LV mid-lateral wall in 45%.

CONCLUSIONS

Epicardial coronary vein anatomy is variable, and the mid-lateral LV wall can potentially be accessed through various tributaries of the epicardial veins. The orientation of the Thebesian valve favors cannulation of the CS from an anterior (ventricular) and inferior approach. Anterobasal, mid-lateral, and inferior apical LV coronary veins lie in proximity to the course of the phrenic nerve.

The Thebesian valve: Gatekeeper to the coronary sinus

Clinical cardiac procedures such as electrophysiology studies, catheter ablation of arrhythmias, retrograde cardioplegia delivery, cardiac resynchronization therapy and, more recently, percutaneous mitral annuloplasty, involve cannulation of the coronary sinus (CS). The presence of a membrane closing the orifice of the CS may cause difficulties during these interventions. Thus, detailed knowledge of the variations and anomalies of the valve of the CS, or the Thebesian valve, now has practical significance. To improve our understanding of this structure, classic anatomical dissection of 50 hearts from dissection room cadavers was performed. A Thebesian valve was present in the overwhelming majority (88%) of cases. Its morphology varied widely, from a few small strands of tissue, to a membrane covering more than half the CS ostium. A significant number (20%) of valves occluded >65% of the ostium, making them "potential complicating factors" in cannulation of the CS. An understanding of these anatomical variations may help in identifying and overcoming potential difficulties during clinical cardiac interventions.

Coronary sinus ostium: the key structure in the heart's anatomy from the electrophysiologist's point of view

There are no research studies that comprehensively analyze, with computed tomography, the coronary sinus (CS) ostium with respect to its importance for some electrophysiological procedures paying special attention to the Thebesian valve (ThebV). Our aim was to evaluate the characteristic features of the CS anatomy, which can be useful for electrophysiologists using multislice computed tomography (MSCT). An additional aim was to create a tomographic classification of ThebV types. Included into the study were 150 patients (aged 59.7 ± 11.4; 105M) (43 with heart failure). Due to the suspicion of coronary artery disease, 64-slice MSCT (Toshiba, Aquilion 64) was performed in all patients. All measurements and the search for the ThebV were performed on multiplanar reconstructions in axial projection at 0.5-mm slice thickness. The average diameter of CS ostium was 14.2 ± 3.5 mm and the angle of entrance of the CS to the right atrium was 112° ± 11°. Seven variants of the ThebV were introduced and six of them were confirmed in this group. The following frequency of variants of ThebV was confirmed: E, 11.3%; D, 10.6%; A1, 8.7%; A2, 7.4%; C, 6.0%; B2, 2.0%. A statistically significant correlation between age and the size of CS ostium was found (r = 0.25; p < 0.05). It is possible to visualize and evaluate the CS including measurements and ThebV evaluation in MSCT. Six anatomical variants of the valve were found. MSCT can potentially provide valuable knowledge before the CS cannulation.

Normal anatomic variants on transthoracic echocardiogram

Apart from their existence as medical curiosities, anatomic variants also double as diagnostic dilemmas. In the heart, more than in any other location in the body, misinterpretation of normal anatomic variants as pathologic entities can have a profound impact on treatment decisions and clinical consequences. Echocardiography is an easily accessible tool these days and is used routinely in most cardiac evaluations. Thus it becomes imperative for the echocardiographer to be cognizant of normal anatomic variants. Furthermore, echocardiographic findings should always be evaluated in their proper clinical context and diagnoses should never be entertained in a clinical vacuum. The literature is replete with numerous case reports and vignettes on these fascinating structures but is lacking in a formal review of normal anatomic variants. In this article, we have attempted a systemic review of normal variants, their embryologic origins, echocardiographic characteristics, and common pitfalls encountered in their evaluation.