Coronary Sinus Ablation Is a Key Player Substrate in Recurrence of Persistent Atrial Fibrillation.

Atrial fibrillation (AF) is the most frequent atrial arrhythmia. During the last few decades, owing to numerous advancements in the field of electrophysiology, we reached satisfactory outcomes for paroxysmal AF with the help of ablation procedures. But the most challenging type is still persistent AF. The recurrence rate of AF in patients with persistent AF is very high, which shows the inadequacy of pulmonary vein isolation (PVI). Over the last few decades, we have been trying to gain insight into AF mechanisms, and have come to the conclusion that there must be some triggers and substrates other than pulmonary veins. According to many studies, PVI alone is not enough to deal with persistent AF. The purpose of our review is to summarize updates and to clarify the role of coronary sinus (CS) in AF induction and propagation. This review will provide updated knowledge on developmental, histological, and macroscopic anatomical aspects of CS with its role as arrhythmogenic substrate. This review will also inform readers about application of CS in other electrophysiological procedures.

The normal electrocardiograms in the conscious newborn lambs in neonatal period and its progression.

BACKGROUND: Veterinary cardiology, especially electrocardiography, has shown major advancements for all animal species. Consequently, the number of ovine species used as experimental animals has increased to date. Few studies have been published on ovine systematic electrocardiography, particularly with respect to lamb physiology and neonatology. This study aimed to standardize the values of normal waves, complexes, and intervals of the electrocardiogram (ECG) in clinically Bergamasca healthy neonatal lambs, used as experimental animals. Serial computerized electrocardiography was performed in 10 male and 12 female neonates on the 1st, 7th, 14th, 21st, 28th, and 35th days of age. The following parameters were analyzed: heart rate and rhythm, duration and amplitude of waves, duration of intervals, and heart electrical axis. RESULTS: During the first 35 days of life, (1) the sinusal heart rhythm was predominant, (2) there was a progressive decrease in the heart rate and R and T wave amplitude, and (3) a progressive increase in the PR, QT, and RR intervals. Finally, we confirmed that various components of neonatal evolution were more discernible in the augmented unipolar leads (aVF), which we recommend should be preferentially used in future studies. No significant statistical alterations were observed between males and females in relation to the analyzed parameters. CONCLUSIONS: The information assimilated in this study is anticipated to enhance the diagnosis of multiple congenital heart defects in Bergamasca lambs and could be implemented in studies that use ovine species as experimental models.

Atrial flutter: more than just one of a kind.

Since its first description about one century ago, our understanding of atrial flutter (AFL) circuits has considerably evolved. One AFL circuit can have variable electrocardiographic (ECG) manifestations depending on the presence of pre-existing atrial lesions, or impaired atrial substrate. Conversely, different (right sided or even left sided) atrial circuits including different mechanisms (macroreentrant, microreentrant, or focal) can present with a very similar surface ECG manifestation. The development of efficient high-resolution electroanatomical mapping systems has improved our knowledge about AFL mechanisms, as well as facilitated their curative treatment with radiofrequency catheter ablation. This article will review ECG features for typical and atypical flutters, and emphasize the limitations for circuit location from the surface ECG.

Left Ventricular Lead Placement Targeted at the Latest Activated Site Guided by Electrophysiological Mapping in Coronary Sinus Branches Improves Response to Cardiac Resynchronization Therapy.

INTRODUCTION: Electrophysiological mapping (EPM) in coronary sinus (CS) branches is feasible for guiding LV lead placement to the optimal, latest activated site at cardiac resynchronization therapy (CRT) procedures. However, whether this procedure optimizes the response to CRT has not been demonstrated. This study was to evaluate effects of targeting LV lead at the latest activated site guided by EPM during CRT. METHODS: Seventy-six consecutive patients with advanced heart failure who were referred for CRT were divided into mapping (MG) and control groups (CG). In MG, the LV lead, also used as a mapping bipolar electrode, was placed at the latest activated site determined by EPM in CS branches. In CG, conventional CRT procedure was performed. Patients were followed for 6 months after CRT. RESULTS: Baseline characteristics were comparable between the 2 groups. In MG (n = 29), EPM was successfully performed in 85 of 91 CS branches during CRT. A LV lead was successfully placed at the latest activated site guided by EPM in 27 (93.1%) patients. Compared with CG (n = 47), MG had a significantly higher rate (86.2% vs. 63.8%, P = 0.039) of response (>15% reduction in LV end-systolic volume) to CRT, a higher percentage of patients with clinical improvement of ≥2 NYHA functional classes (72.4% vs. 44.7%, P = 0.032), and a shorter QRS duration (P = 0.004). CONCLUSIONS: LV lead placed at the latest activated site guided by EPM resulted in a significantly greater CRT response, and a shorter QRS duration.

Mathematical modeling of aortic valve dynamics during systole.

We have derived a mathematical model describing aortic valve dynamics and blood flow during systole. The model presents a realistic coupling between aortic valve dynamics, sinus vortex local pressure, and variations in the systemic vascular resistance. The coupling is introduced by using Hill׳s classical semi-spherical vortex model and an aortic pressure-area compliance constitutive relationship. The effects of introducing aortic sinus eddy vortices and variable systemic vascular resistance on overall valve opening-closing dynamics, left ventricular pressure, aortic pressure, blood flow rate, and aortic orifice area are examined. In addition, the strength of the sinus vortex is coupled explicitly to the valve opening angle, and implicitly to the aortic orifice area in order to predict how vortex strength varies during the four descriptive phases of aortic valve motion (fast-opening, fully-opening, slow-closing, and fast-closing). Our results compare favorably with experimental observations and the model reproduces well-known phenomena corresponding to aortic valve function such as the dicrotic notch and retrograde flow at end systole. By invoking a more complete set of physical phenomena, this new model will enable representation of pathophysiological conditions such as aortic valve stenosis or insufficiency, making it possible to predict their integrated effects on cardiac load and systemic hemodynamics.

Intracoronary hemodynamic effects of pressure-controlled intermittent coronary sinus occlusion (PICSO): results from the First-In-Man Prepare PICSO Study.

BACKGROUND: Myocardial reperfusion is frequently suboptimal after ST-segment elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (PCI). Using a balloon-tipped catheter positioned in the coronary sinus (CS), pressure-controlled intermittent coronary sinus occlusion (PICSO) results in an intermittent obstruction of coronary venous outflow of the left anterior descending artery (LAD), and may improve myocardial perfusion by augmenting redistribution of blood to the border zone of ischemic myocardium. We sought to document the intracoronary hemodynamic effects of PICSO during PCI. METHODS: We included 15 patients with stable angina scheduled for PCI of the LAD. Balloon occlusion of the LAD was performed twice, once with and once without PICSO and lasting maximally 3 minutes each, to document the effect of PICSO on CS pressure and LAD wedge pressure. RESULTS: Catheter delivery was successful in all patients. The study protocol could not be conducted in 5 patients due to initial calibration difficulties (n = 3), a pressure wire problem (n = 1), and a vagal response at the start of the procedure (n = 1). In the remaining 10 patients, CS occlusion caused a marked increase in mean CS pressure (4.1 ± 7.3 mmHg vs. 22.0 ± 12.6 mmHg; P < 0.001) and CS pulse pressure (4.3 ± 0.8 mmHg vs. 36.1 ± 6.3 mmHg; P < 0.001). Concomitantly, mean distal LAD wedge pressure and wedge pulse pressure increased (32.4 ± 12.2 mmHg vs. 35.5 ± 12.6 mmHg; P < 0.001 and 39.1 ± 27.2 mmHg vs. 45.9 ± 26.0 mmHg; P < 0.001, respectively). At 30 day follow-up, no device-related events occurred. CONCLUSIONS: PICSO safely augments CS pressure, thereby increasing LAD coronary wedge pressure. These findings support further evaluation of PICSO in the setting of STEMI.

Changing coronary sinus activation during catheter ablation of isthmus-dependent right atrial flutter: what is the mechanism?

A 69-year-old woman was referred for cavotricuspid isthmus ablation due to typical isthmus-dependent right atrial flutter. During ablation, intracardiac activation sequence in coronary sinus (CS) changed without altering the cycle length or the P-wave morphology. This suggests that interatrial connection via CS was blocked and left atrium (LA) was activated from Bachmann's bundle or/and connections between fossa ovalis and LA.

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.

Gender differences in response to cold pressor test assessed with velocity-encoded cardiovascular magnetic resonance of the coronary sinus.

BACKGROUND: Gender-specific differences in cardiovascular risk are well known, and current evidence supports an existing role of endothelium in these differences. The purpose of this study was to assess non invasively coronary endothelial function in male and female young volunteers by myocardial blood flow (MBF) measurement using coronary sinus (CS) flow quantification by velocity encoded cine cardiovascular magnetic resonance (CMR) at rest and during cold pressor test (CPT). METHODS: Twenty-four healthy volunteers (12 men, 12 women) underwent CMR in a 3 Tesla MR imager. Coronary sinus flow was measured at rest and during CPT using non breath-hold velocity encoded phase contrast cine-CMR. Myocardial function and morphology were acquired using a cine steady-state free precession sequence. RESULTS: At baseline, mean MBF was 0.63 ± 0.23 mL·g⁻¹·min⁻¹ in men and 0.79 ± 0.21 mL·g⁻¹·min⁻¹ in women. During CPT, the rate pressure product in men significantly increased by 49 ± 36% (p < 0.0001) and in women by 52 ± 22% (p < 0.0001). MBF increased significantly in both men and women by 0.22 ± 0.19 mL·g⁻¹·min⁻¹ (p = 0.0022) and by 0.73 ± 0.43 mL·g⁻¹·min⁻¹ (p = 0.0001), respectively. The increase in MBF was significantly higher in women than in men (p = 0.0012). CONCLUSION: CMR coronary sinus flow quantification for measuring myocardial blood flow revealed a higher response of MBF to CPT in women than in men. This finding may reflect gender differences in endothelial-dependent vasodilatation in these young subjects. This non invasive rest/stress protocol may become helpful to study endothelial function in normal physiology and in physiopathology.

Left ventricular mechanical activity detected by impedance recording.

AIMS: Recording and analysing impedance fluctuation along the cardiac cycle in the right (RV) and left ventricles (LV). METHODS AND RESULTS: During a biventricular (BiV) implantation procedure, impedance was sequentially derived between the atrial ring electrode and either electrode (tip or ring) of the RV lead [transvalvular impedance (TVI)], and between the atrial ring and either the tip or ring electrode of a coronary sinus lead, positioned in a cardiac vein [left ventricle impedance (LVI)]. The LVI signal was also recorded by the implanted pacemaker at the 1 day and 3 months follow-ups. With intrinsic conduction, TVI showed an average increase of 53 +/- 29 ohm during ventricular systole, whereas at the same time, LVI decreased by 45 +/- 21 ohm (25 and 23 patients, respectively, out of 28 tested cases). Transvalvular impedance and LVI displayed a similar time course, which appeared to be related to the systolic timing in the RV and LV. Both LVI amplitude and duration decreased as a function of the cardiac rate. The LVI deflection started immediately after LV stimulation, and often anticipated the R-wave sensing after contralateral pacing. At the 3-month follow-up, LVI amplitude was decreased in 70% of cases and increased in the remainder, with a non-significant average change of -5 +/- 85% with respect to the acute recordings. CONCLUSION: Transvalvular impedance properties are consistent with the assumption of an inverse relationship with RV volume. Though LVI requires a different physical interpretation, the waveform duration might reflect the timing of LV myocardial contraction. In this hypothesis, the relationship between TVI and LVI could provide insight into the effects of BiV pacing on mechanical synchronization.

Concealed left superior accessory pathway. Distinctive features of retrograde atrial activation and successful ablation using transseptal approach.

Concealed left superior accessory pathways are very infrequent and can be difficult to diagnose and ablate. We describe here the case of a patient presenting with reciprocating tachycardia involving superior and inferior left accessory pathways. Left superior accessory pathway was suspected because of the simultaneous retrograde atrial activation at the distal coronary sinus (CS) and His bundle lead and could be successfully ablated using transseptal catheterization.

Significant left atrial appendage activation delay complicating aggressive septal ablation during catheter ablation of persistent atrial fibrillation.

BACKGROUND: This study aims to describe significant left atrial appendage activation following ablation of persistent atrial fibrillation, and explore its relationship with aggressive septal ablation. METHODS AND RESULTS: Significant left atrial appendage activation delay was found in 23 out of 201 patients undergoing persistent atrial fibrillation ablation. Of them, 14 were found in their index procedures, of whom septal line ablation was performed in nine (odds ratio 15.2, 95% confidence interval 4.6-50.8, P < 0.001). Another nine were found during their redo procedures (including two with biatrial activation dissociation), all of whom received extensive left septal complex fractionated electrograms ablation in their prior procedures (P = 0.002). Electrocardiograph showed split P wave with the latter component merged into the QRS wave. Activation mapping demonstrated the earliest breakthrough of the left atrium changed to coronary sinus in 18 (85.7%) patients. After 1 month, the mitral A wave velocity was 18.2 +/- 17.0 cm/s, and decreased significantly as compared with preablation (20.2 +/- 19.1 vs 58.2 +/- 17.9 cm/s, P = 0.037) in patients undergoing redo procedures. Fourteen (60.9%) remained arrhythmia-free during follow-up for 10.6 +/- 6.2 months. CONCLUSION: Septal line ablation and extensive septal complex fractionated electrograms ablation are correlated with significant left atrial activation delay or even biatrial activation dissociation, and should be performed with prudent consideration.

The anatomy of the coronary sinus venous system for the cardiac electrophysiologist.

Cardiac electrophysiologists' use of the coronary sinus (CS) to map and ablate accessory pathways and implant left ventricular leads has emphasized the need for understanding CS anatomy. In this review, we briefly examine the developmental and radiological anatomy of the CS and discuss in detail the gross anatomy of this cardiac vein. We highlight the correlations of the acquired anatomical knowledge relevant to clinical electrophysiology practice.

Quantifying coronary sinus flow and global LV perfusion at 3T.

BACKGROUND: Despite the large availability of 3T MR scanners and the potential of high field imaging, this technical platform has yet to prove its usefulness in the cardiac MR setting, where 1.5T remains the established standard. Global perfusion of the left ventricle, as well as the coronary flow reserve (CFR), can provide relevant diagnostic information, and MR measurements of these parameters may benefit from increased field strength. Quantitative flow measurements in the coronary sinus (CS) provide one method to investigate these parameters. However, the ability of newly developed faster MR sequences to measure coronary flow during a breath-hold at 3T has not been evaluated. METHODS: The aim of this work was to measure CS flow using segmented phase contrast MR (PC MR) on a clinical 3T MR scanner. Parallel imaging was employed to reduce the total acquisition time. Global LV perfusion was calculated by dividing CS flow with left ventricular (LV) mass. The repeatability of the method was investigated by measuring the flow three times in each of the twelve volunteers. Phantom experiments were performed to investigate potential error sources. RESULTS: The average CS flow was determined to 88 +/- 33 ml/min and the deduced LV perfusion was 0.60 +/- 0.22 ml/min.g, in agreement with published values. The repeatability (1-error) of the three repeated measurements in each subject was on average 84%. CONCLUSION: This work demonstrates that the combination of high field strength (3T), parallel imaging and segmented gradient echo sequences allow for quantification of the CS flow and global perfusion within a breath-hold.

Cardiac veins: a review of the literature.

Cardiac veins have long stood in the shadow of their more extensively studied counterparts, the coronary arteries. The clinical importance of the coronary venous system, nonetheless, should not be underestimated. Intricate and beneficial therapeutic options are increasingly being developed that depend on knowledge of the structure of this venous network. Such interventions have been shown greatly to promote cardiac health, and to enhance the efficacy of cardiac pacing. A comprehensive appreciation of the architecture of the coronary venous system, therefore, is crucial to optimal cardiac care. It is possible to provide an overview of the arrangement of the cardiac veins, with the larger veins draining to the coronary sinus, and thence to the right atrium, but with smaller and minimal veins draining directly to the cavities of the atrial chambers. The venous pathways, nonetheless, are highly variable, making exceptions the commonly accepted rule. As such, unique solutions for imaging, and simple attentiveness to possible venous variations, can greatly enhance clinical outcomes. For example, identifying the diameter, course, and valves of the cardiac veins allows for anticipation of impediments during interventional procedures, and allows for informed clinical decision-making. Also of significance is awareness of alternate arrangements that may be encountered in terms of venous drainage, and the importance of intramural venous collecting spaces in these patterns. The objective of our review, therefore, is to explore and describe the anatomical distribution of the coronary veins.

The impact of coronary sinus narrowing on diastolic function in patients with refractory angina.

OBJECTIVE: Evaluating the impact of Coronary sinus (CS) narrowing on diastolic function. BACKGROUND: Narrowing of the CS is an emerging therapy for refractory angina pectoris, improving perfusion to the ischemic subendocardium and relieving ischemia and angina. It was speculated that increased CS pressure might cause interstitial myocardial edema and diastolic dysfunction. METHODS: Prospective assessment of diastolic function was performed at baseline and 6 months following CS Reducer implantation in consecutive patients treated for refractory angina. Diastolic function assessment included left atrial volume, early transmitral filling peak velocity (E wave), E wave deceleration time (DT), transmitral atrial wave velocity (A wave), and early diastolic velocity of the septal (e' septal) and lateral (e' lateral) aspects of the mitral annulus. RESULTS: Twenty-four patients with chronic refractory angina and proven myocardial ischemia (mean age 69.3 ±â€¯10.9 years) were included in the analysis. A wave velocity, E/A ratio, E wave DT and left atrial volume did not significantly change 6 months following Reducer implantation (p > 0.1 for all comparisons). A non-significant decrease in E wave velocity (80.5 ±â€¯22.3 cm/s vs. 75.7 ±â€¯17.5 cm/s, p = 0.19) and non significant increase in e' septal and lateral (5.28 ±â€¯1.54 cm/s vs. 5.30 ±â€¯1.71 cm/s, p = 0.95 and 8.26 ±â€¯1.85 cm/s vs. 8.46 ±â€¯2.07 cm/s, p = 0.69, respectively) led to a non-significant decrease in E/e' average ratio (12.6 ±â€¯5.7 vs. 11.4 ±â€¯3.3, p = 0.24). Mean diastolic function class significantly decreased following Reducer implantation from 1.5 ±â€¯0.66 to 1.17 ±â€¯0.76 (p = 0.008). CONCLUSION: Coronary sinus narrowing in patients with myocardial ischemia and refractory angina does not adversely affect diastolic function and may actually improve it.

[The role of coronary sinus musculature on electrical conduction between left atrium and right atrium in isolated canine heart].

OBJECTIVE: To investigate electrophysiological characteristics of the coronary sinus musculature and explore its role on electrical conduction between left atrium and right atrium in isolated canine heart. METHOD: The electrical connections between coronary sinus, left atrium and right atrium were detected by programmed stimulation delivered at coronary sinus ostium, distal coronary sinus and lateral wall of left atrium in a Langendorff model of canine. RESULTS: During stimulation delivered at coronary sinus ostium and distal coronary sinus, posterior wall of left atrium was firstly activated by electronic signal through coronary sinus musculature, the conduct time of coronary sinus ostium stimulation and distal coronary sinus stimulation were (44 +/- 21) ms and (41 +/- 15) ms, respectively. During stimulation delivered at lateral wall of left atrium, electronic signal was firstly observed in coronary sinus. During premature stimulation, conduction blockade of coronary sinus to left atrium was evidenced in parts of hearts, but electronic conduction of left atrium to right atrium remained stable. The ERP at the different stimulation sites of coronary sinus ostium and distal coronary sinus, posterior wall of left atrium were (122 +/- 19) ms, (114 +/- 12) ms (n = 3) and (107 +/- 17) ms (all P > 0.05). CONCLUSION: A conduction way connecting left and right atria exists in coronary sinus which might play an important role on inducing and maintaining atrial arrhythmias under certain pathological conditions.

What is the most appropriate method for coronary sinus cannulation? The telescopic method or the electrophysiologic method?

OBJECTIVES: The most challenging stage of cardiac resynchronization therapy (CRT) is coronary sinus cannulation (CS). The aim of this study was to compare coronary sinus cannulation techniques using electrophysiology catheters and coronary angiography catheters. METHODS: In this observational, retrospective and non-randomized study, 87 patients who were eligible for CRT device implantation were screened at Kahramanmaras Sutcu Imam University Hospital between March 2014 and March 2018. Seventy-two patients who met the inclusion criteria were enrolled in the study. The study population was divided into 2 groups: the first group consisted of 36 patients whose coronary sinuses were cannulated via electrophysiology (EP) catheters and the second group included 36 patients who received coronary angiography catheters for coronary sinus cannulation. RESULTS: The two groups were similar in terms of the baseline characteristics of the patients. The total fluoroscopy time was less with cannulation using coronary angiography catheters. There were no differences between the two groups in terms of the amount of contrast material and the success of the operations. CONCLUSIONS: Coronary sinus catheterization using coronary angiography catheters significantly reduces fluoroscopy time in patients undergoing CRT.

Flow velocity is relatively uniform in the coronary sinusal venous tree: structure-function relation.

The structure and function of coronary venous vessels are different from those of coronary arteries and are much less understood despite the therapeutic significance of coronary sinus interventions. Here we aimed to perform a hemodynamic analysis in the entire coronary sinusal venous tree, which enhances the understanding of coronary venous circulation. A hemodynamic model was developed in the entire coronary sinusal venous tree reconstructed from casts and histological data of five swine hearts. Various morphometric and hemodynamic parameters were determined in each vessel and analyzed in the diameter-defined Strahler system. The findings demonstrate an area preservation between the branches of the coronary venous system that leads to relatively uniform flow velocity in different orders of the venous tree. Pressure and circumferential and wall shear stresses decreased abruptly from the smallest venules toward vessels of order -5 (80.4 ± 39.1 µm) but showed a more modest change toward the coronary sinus. The results suggest that vessels of order -5 denote a hemodynamic transition from the venular bed to the transmural subnetwork. In contrast with the coronary arterial tree, which obeys the minimum energy hypothesis, the coronary sinusal venous system complies with the area-preserving rule for efficient venous return, i.e., da Vinci's rule. The morphometric and hemodynamic model serves as a physiological reference state to test various therapeutic rationales through the venous route. NEW & NOTEWORTHY: A hemodynamic model is developed in the entire coronary sinusal venous tree of the swine heart. A key finding is that the coronary sinusal venous system complies with the area preservation rule for efficient venous return while the coronary arterial tree obeys the minimum energy hypothesis. This model can also serve as a physiological reference state to test various therapeutic rationales through the venous route.