Incremental prognostic value of coronary flow reserve determined by phase-contrast cine cardiovascular magnetic resonance of the coronary sinus in patients with diabetes mellitus

BACKGROUND

Although non-invasive assessment of coronary flow reserve (CFR) by cardiovascular magnetic resonance (CMR) provides prognostic information for patients with diabetes mellitus (DM), the incremental prognostic value of CMR-derived CFR remains unclear.

PURPOSE

To evaluate the incremental prognostic value of CMR-derived CFR for patients with DM who underwent stress CMR imaging.

MATERIALS AND METHODS

A total of 309 patients with type 2 DM [69 ± 9 years; 244 (78%) male] assessed between 2009 and 2019 were retrospectively reviewed. Coronary sinus blood flow (CSBF) was measured using phase contrast (PC) cine CMR. CFR was calculated as the CSBF during adenosine triphosphate infusion divided by that at rest. Major adverse cardiac events (MACE) were defined as death, acute coronary syndrome, hospitalization due to heart failure exacerbation, or sustained ventricular tachycardia. The incremental prognostic value of CFR over clinical and CMR variables was assessed by calculating the C-index and net reclassification improvement (NRI).

RESULTS

During a median follow-up of 3.8 years, 42 patients (14%) experienced MACE. The annualized event rate was significantly higher among patients with CFR < 2.0, regardless of the presence of late gadolinium enhancement (LGE) (1.4% vs. 9.8%, p = 0.011 in the LGE (-) group; 1.8% vs. 16.9%, p < 0.001 in the LGE (+) group). In addition, this trend was maintained in the subgroups stratified by presence or absence of ischemia (0.3% vs. 6.7%, p = 0.007 in the ischemia (-) group; 3.9% vs. 17.1%, p = 0.001 in the ischemia (+) group). Adding CFR to the risk model (age + gender + left ventricular ejection fraction + %LGE + %ischemia) resulted in a significant increase of the C-index from 0.838 to 0.870 (p = 0.038) and an NRI of 0.201 (0.004-0.368, p = 0.012).

CONCLUSION

PC cine CMR-derived CFR of the coronary sinus may be useful as a prognostic marker for DM patients, incremental to common clinical and CMR parameters. Due to the high prevalence of coronary microvascular dysfunction, the addition of CFR to conventional vasodilator stress CMR imaging may improve risk stratification for patients with DM.

Impact of Leaflet Laceration on Transcatheter Aortic Valve-in-Valve Washout: BASILICA to Solve Neosinus and Sinus Stasis

OBJECTIVES

The aim of this study was to evaluate any potential leaflet washout benefits after bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction during TAVR (BASILICA) in transcatheter valve-in-valve (ViV) in the context of leaflet thrombosis.

BACKGROUND

Leaflet thrombosis after transcatheter aortic valve replacement is secondary to flow stasis in both the sinus and neosinus. Strategies to improve washout and ameliorate neosinus and sinus flow velocities may have the potential to mitigate the occurrence of clinical and subclinical leaflet thrombosis.

METHODS

A 23-mm Edwards SAPIEN 3 and a 26-mm Medtronic Evolut were deployed in a 23-mm transparent surgical aortic valve model before and after leaflet laceration. The valves were placed in the aortic position of a pulse duplicator flow loop. Particle image velocimetry was performed to quantify sinus flow hemodynamic status. A tracing fluorescent dye was injected to evaluate the number of cycles to washout in both regions of interest.

RESULTS

The leaflet laceration procedure led to an increase in the velocities in the sinus and the neosinus by 50% for Evolut ViV and 61.9% for SAPIEN 3 ViV. In addition, leaflet laceration led to a reduction in overall cycles to washout in the neosinus by at least 56% with the Evolut and 54.5% with the SAPIEN 3 and in the sinus by at least 16.7% with the Evolut and 60.8% with the SAPIEN.

CONCLUSIONS

Leaflet laceration using a BASILICA-type approach may hold the potential to mitigate neosinus and sinus flow stasis. Controlled in vivo trials are necessary to establish the potential benefit of BASILICA to reduce the occurrence of leaflet thrombosis.

Beyond Pulmonary Vein Isolation in Nonparoxysmal Atrial Fibrillation: Posterior Wall, Vein of Marshall, Coronary Sinus, Superior Vena Cava, and Left Atrial Appendage

The optimal ablation strategy for non-paroxysmal atrial fibrillation remains controversial. Non-PV triggers have been shown to have a major arrhythmogenic role in these patients. Common sources of non-PV triggers are: posterior wall, left atrial appendage, superior vena cava, coronary sinus, vein of Marshall, interatrial septum, crista terminalis/Eustachian ridge, and mitral and tricuspid valve annuli. These sites are targeted empirically in selected cases or if significant ectopy is noted (with or without a drug challenge), to improve outcomes in patients with non-paroxysmal atrial fibrillation. This article focuses on summarizing the current evidence and the approach to mapping and ablation of these frequent non-PV trigger sites.

STIM1-Ca2+ signaling in coronary sinus cardiomyocytes contributes to interatrial conduction

Pacemaker action potentials emerge from the sinoatrial node (SAN) and rapidly propagate through the atria to the AV node via preferential conduction pathways, including one associated with the coronary sinus. However, few distinguishing features of these tracts are known. Identifying specific molecular markers to distinguish among these conduction pathways will have important implications for understanding atrial conduction and atrial arrhythmogenesis. Using a Stim1 reporter mouse, we discovered stromal interaction molecule 1 (STIM1)-expressing coronary sinus cardiomyocytes (CSC)s in a tract from the SAN to the coronary sinus. Our studies here establish that STIM1 is a molecular marker of CSCs and we propose a role for STIM1-CSCs in interatrial conduction. Deletion of Stim1 from the CSCs slowed interatrial conduction and increased susceptibility to atrial arrhythmias. Store-operated Ca²⁺ currents (I_soc) in response to Ca²⁺ store depletion were markedly reduced in CSCs and their action potentials showed electrical remodeling. Our studies identify STIM1 as a molecular marker for a coronary sinus interatrial conduction pathway. We propose a role for SOCE in Ca²⁺ signaling of CSCs and implicate STIM1 in atrial arrhythmogenesis.

Coronary venous anatomy and anomalies

Coronary venous anatomy can be divided into the greater cardiac venous system and the lesser cardiac venous system. With protocol optimization, including appropriate contrast bolus timing, coronary veins can be depicted with excellent detail on CT. Knowledge of variant coronary venous anatomy can sometimes play a role in pre-procedural planning. Analysis of the coronary venous anatomy on CT can detect coronary venous anomalies that cause right to left shunts with risk of stroke, left to right shunts, and arrhythmias.

Coronary sinus as a site for stable temporary atrial pacing to tide over premature ventricular complex-triggered recurrent ventricular fibrillation in a patient with severe left ventricular dysfunction after coronary bypass surgery

Use of atrial pacing has been known, yet underutilized tool for effective temporary pacing whenever needed early after cardiac surgery. The reasons may be frequent failures of epicardial wires (fixed over atria intra-operative) leading to loss of capture. Endocardial atrial pacing sites for temporary pacing are unstable and hence continuous pacing with acceptable thresholds is impossible. We describe a case of ischemic cardiomyopathy and severe left ventricle systolic dysfunction who required atrial pacing post coronary artery bypass grafting (CABG) surgery for around 48–72 hours starting 4th day post operation when he had multiple episodes of ventricular fibrillation (VF) needing many defibrillation shocks. VF episodes were triggered by premature ventricular complexes (PVC) falling on as R on T. Episodes were refractory to anti-arrhythmic drugs and general anesthesia. These PVC were successfully overdriven by atrial pacing by fluoroscopically placing pacing lead in coronary sinus. This led to complete suppression of PVC induced VF for next 48–72 hours while the antiarrhythmic drugs were continued. Subsequently the patient was discharged in stable state. Atrial pacing, though quite valuable during the post-operative period after cardiac surgery, is underutilized, especially when pacing through surgically placed epicardial wire fails. This report is helpful in drawing attention towards coronary sinus (CS) as an alternate site for achieving stable, temporary atrial pacing during the post-operative period. This site can also be utilized for short term dual chamber pacing if required in post-operative state using transvenous CS site for atrial pacing and intraoperatively placed epicardial wire for ventricular pacing.

Unlocking data sets by calibrating populations of models to data density: A study in atrial electrophysiology

The understanding of complex physical or biological systems nearly always requires a characterization of the variability that underpins these processes. In addition, the data used to calibrate these models may also often exhibit considerable variability. A recent approach to deal with these issues has been to calibrate populations of models (POMs), multiple copies of a single mathematical model but with different parameter values, in response to experimental data. To date, this calibration has been largely limited to selecting models that produce outputs that fall within the ranges of the data set, ignoring any trends that might be present in the data. We present here a novel and general methodology for calibrating POMs to the distributions of a set of measured values in a data set. We demonstrate our technique using a data set from a cardiac electrophysiology study based on the differences in atrial action potential readings between patients exhibiting sinus rhythm (SR) or chronic atrial fibrillation (cAF) and the Courtemanche-Ramirez-Nattel model for human atrial action potentials. Not only does our approach accurately capture the variability inherent in the experimental population, but we also demonstrate how the POMs that it produces may be used to extract additional information from the data used for calibration, including improved identification of the differences underlying stratified data. We also show how our approach allows different hypotheses regarding the variability in complex systems to be quantitatively compared.

From time-series to complex networks: Application to the cerebrovascular flow patterns in atrial fibrillation

A network-based approach is presented to investigate the cerebrovascular flow patterns during atrial fibrillation (AF) with respect to normal sinus rhythm (NSR). AF, the most common cardiac arrhythmia with faster and irregular beating, has been recently and independently associated with the increased risk of dementia. However, the underlying hemodynamic mechanisms relating the two pathologies remain mainly undetermined so far; thus, the contribution of modeling and refined statistical tools is valuable. Pressure and flow rate temporal series in NSR and AF are here evaluated along representative cerebral sites (from carotid arteries to capillary brain circulation), exploiting reliable artificially built signals recently obtained from an in silico approach. The complex network analysis evidences, in a synthetic and original way, a dramatic signal variation towards the distal/capillary cerebral regions during AF, which has no counterpart in NSR conditions. At the large artery level, networks obtained from both AF and NSR hemodynamic signals exhibit elongated and chained features, which are typical of pseudo-periodic series. These aspects are almost completely lost towards the microcirculation during AF, where the networks are topologically more circular and present random-like characteristics. As a consequence, all the physiological phenomena at the microcerebral level ruled by periodicity-such as regular perfusion, mean pressure per beat, and average nutrient supply at the cellular level-can be strongly compromised, since the AF hemodynamic signals assume irregular behaviour and random-like features. Through a powerful approach which is complementary to the classical statistical tools, the present findings further strengthen the potential link between AF hemodynamic and cognitive decline.

Prognostic significance of myocardial energy expenditure and myocardial efficiency in patients with heart failure with reduced ejection fraction

In heart failure with reduced ejection fraction (HFrEF) patients, myocardial blood flow (MBF), myocardial energy expenditure (MEE), myocardial efficiency has been poorly evaluated because of the necessity of invasive procedures in the determination of these parameters. Transthoracic echocardiography (TTE) can provide reliable data for MEE, MBF (via coronary sinus (CS) flows). Also, myocardial efficiency can be evaluated by the MEE to MBF ratio. We aim to assess MBF, MEE and energy efficiency and the prognostic value of these parameters in HFrEF. In this prospective study, a total of 80 patients with HFrEF due to either ischemic or non-ischemic etiology and 20 healthy control subjects were included. Median follow-up duration was 901 (27-1004) days. MBF was calculated via coronary sinus blood flow. MEE was measured from circumferential end-systolic stress, stroke volume and left ventricular ejection time. MEE to MBF ratio was determined as MEf. Primary composite end-point (CEP) was cardiovascular mortality, heart transplantation or mechanical circulatory support. MEE and MEf were lower and MBF per minute was higher in HF group compared to control subjects whereas MBF per 100 g left ventricular mass was not different. MEE and MEf have significantly negative correlation with troponin I, BNP, uric acid and positive correlation with epicardial fat thickness. In Cox regression analysis, per one calorie decrease of MEE was associated 4.3 times increased risk [HR 4.396 (95% CI 1.230-15.716)] and per one percent decrease of MEf was associated 3.3 times increased risk of CEP [HR 3.343 (95% CI 1.025-10.905)]. Our study demonstrated that while MEE and MEf diminished in HFrEF, MBF preserved with the symptomatic progression of HF. MEE and MEf were found to be associated with important prognostic markers and independent predictors of CEP in HFrEF. Evaluation of MEE, MBF and MEf with echocardiography may provide an additional data regarding prognostic assessment of HFrEF population.

Coronary sinus activation patterns in patients with and without left bundle branch block undergoing electroanatomic mapping system-guided cardiac resynchronization therapy device implantation

BACKGROUND

Implantation of the left ventricular (LV) lead in segments with delayed electrical activation may improve response to cardiac resynchronization therapy (CRT).

OBJECTIVE

The purpose of this study was to evaluate the amount and regional distribution of LV electrical delay (LVED) in patients with or without left bundle branch block (LBBB).

METHODS

We enrolled 60 patients who underwent electroanatomic mapping system-guided CRT device implantation. Activation mapping of the coronary sinus (CS) branches was performed using an insulated guidewire. LVED was defined as the interval between the beginning of the QRS complex on the surface electrocardiogram (ECG) and the local electrogram and expressed in milliseconds or as percentage of the total QRS duration (LVED%).

RESULTS

Forty-three patients showed a LBBB and 17 a non-LBBB electrocardiographic pattern. A total of 148 CS branches (mean 2.5 per patient; range 2-4 per patient) were mapped. Patients with LBBB showed higher maximum LVED (135 ms [108-150 ms] vs 100 ms [103-110 ms]; P < .001) and LVED% (86% [79%-89%] vs 72% [54%-80%]; P < .001) than did patients without LBBB. The maximum LVED was recorded in mid-basal anterolateral or inferolateral LV segments (traditional CRT targets), significantly more often in patients with LBBB than in patients without LBBB (85% vs 59%; P = .02). The number of CS branches showing LVED >50% of the total QRS duration, >75% of the total QRS duration, and >85 ms was significantly higher in patients with LBBB than in patients without LBBB.

CONCLUSION

Patients without LBBB showed lower LVED and more heterogeneous electrical activation of the CS than did patients with LBBB. This finding may contribute to a lower rate of response to CRT of patients without LBBB and suggests the use of activation mapping to guide LV lead placement.

Venous Myocardial Infarction in an Infant with Obstructed Totally Anomalous Pulmonary Venous Drainage and Coronary Sinus Ostial Atresia

We report a rare causal association between obstructed supracardiac totally anomalous pulmonary venous drainage and coronary sinus ostial atresia. Our 12-week-old patient developed venous myocardial infarction secondary to coronary venous hypertension because her sole route of coronary venous drainage was obstructed. She recovered after the obstruction was relieved by balloon dilation. Surgical repair then included anastomosis of the pulmonary venous confluence to the left atrium, ligation of the vertical vein, and unroofing of the coronary sinus. Coronary sinus ostial atresia is rarely diagnosed before autopsy.

Coronary Sinus Flow Is Reduced and Recovered With Time in Viral Myocarditis Mimicking Acute Coronary Syndrome: A Transthoracic Doppler Echocardiographic Study

OBJECTIVES

The clinical presentation of myocarditis often mimics acute coronary syndrome. Coronary sinus flow has been used for detection of the presence of myocardial ischemia. Whether myocarditis is associated with changes in coronary sinus flow remains unknown. The aim of this study was to assess coronary sinus flow at the onset and follow-up of myocarditis mimicking acute coronary syndrome using transthoracic Doppler echocardiography (TTE).

METHODS

Sixty-four patients with clinically diagnosed viral myocarditis mimicking acute coronary syndrome underwent TTE on days 3, 7, 30, 90, 180, and 360 after onset. Coronary sinus flow was compared among different points in time.

RESULTS

Compared to healthy participants, all patients with myocarditis had a larger cardiac size, reduced cardiac function, and electrocardiographic and myocardial enzyme abnormalities on days 3 and 7 days (P< .01; P< .05). They later had gradual restoration to normal levels. On days 3 and 7, the coronary sinus flow in patients with myocarditis was extremely lower than that in healthy participants (about one-tenth), although coronary angiography revealed unobstructed arteries. On days 30, 90, 180, and 360, the coronary sinus flow had been increasing; however, it was still far less than that in healthy participants (P < .01).

CONCLUSIONS

Coronary sinus flow depicted by TTE is reduced but recovers with time in viral myocarditis mimicking acute coronary syndrome, which is a useful indicator in the follow-up of this type of myocarditis.

β1-Adrenergic and M2 Muscarinic Autoantibodies and Thyroid Hormone Facilitate Induction of Atrial Fibrillation in Male Rabbits

Activating autoantibodies to the β1-adrenergic and M2 muscarinic receptors are present in a very high percentage of patients with Graves' disease and atrial fibrillation (AF). The objective of this study was to develop a reproducible animal model and thereby to examine the impact of these endocrine-like autoantibodies alone and with thyroid hormone on induction of thyroid-associated atrial tachyarrhythmias. Five New Zealand white rabbits were coimmunized with peptides from the second extracellular loops of the β1-adrenergic and M2 muscarinic receptors to produce both sympathomimetic and parasympathomimetic antibodies. A catheter-based electrophysiological study was performed on anesthetized rabbits before and after immunization and subsequent treatment with thyroid hormone. Antibody expression facilitated the induction of sustained sinus, junctional and atrial tachycardias, but not AF. Addition of excessive thyroid hormone resulted in induced sustained AF in all animals. AF induction was blocked acutely by the neutralization of these antibodies with immunogenic peptides despite continued hyperthyroidism. The measured atrial effective refractory period as one parameter of AF propensity shortened significantly after immunization and was acutely reversed by peptide neutralization. No further decrease in the effective refractory period was observed after the addition of thyroid hormone, suggesting other cardiac effects of thyroid hormone may contribute to its role in AF induction. This study demonstrates autonomic autoantibodies and thyroid hormone potentiate the vulnerability of the heart to AF, which can be reversed by decoy peptide therapy. These data help fulfill Witebsky's postulates for an increased autoimmune/endocrine basis for Graves' hyperthyroidism and AF.

Effects of the self-myocardial retroperfusion with aortic-coronary sinus shunt on cardiac output and ischemic events in high-risk patients undergoing OPCAB surgery

AIM

Despite controversies, off-pump coronary artery bypass (OPCAB) surgery has become a routine procedure. Obvious advantages have been demonstrated in high-risk patients. However, OPCAB surgery has limitations in specific high-risk situations with hazards of operative deleterious events. We describe an innovative procedure of self-myocardial retroperfusion (SMR) with an aortic-coronary sinus shunt (ACSS). We prospectively evaluated the protective effects and benefits of SMR in high-risk coronary patients with impaired LVEF.

METHODS

Eighteen consecutive high-risk (ES>10) coronary patients (mean age: 65.94 years; range: 34-85; mean ES: 26.97%) with LVEF≤35% who were not eligible for IABP were assigned for OPCAB surgery. Following sternotomy, the cardiac indexes (CI) were measured before, during SMR and after completion of coronary artery bypasses. Operative events with and without SMR were accurately collected, and postoperative cardiac Troponin T release was measured.

RESULTS

OPCAB procedures were performed in all patients. Intraoperative use of SMR significantly increased CI (P=3.1041810.10-8) and reversed deleterious operative events (ECG changes/low cardiac output). Hospital mortality was 0%. Incidence of transient atrial fibrillation was 33.33%. Neither stroke nor renal insufficiency was observed. The mean graft number/patient was 2.05. Mean postoperative cardiac Troponin T value was 0.79 μg/L. Beating heart preservation optimized by SMR contributed to reduce ischemia-reperfusion injury, as validated by an immediate increase of CI after completion of coronary bypasses (P=3.35009.10-9).

CONCLUSION

The concept of SMR with an ACSS during OPCAB procedures definitely improved CI and reversed ischemic features in high-risk patients and should be considered as an operative temporary myocardial assistance.

Prognostic significance of coronary sinus filling time in patients with angina and normal coronaries at one year follow up

BACKGROUND

Coronary sinus filling time (CSFT) has been proposed as a simple method for assessment of coronary microvascular function in patients with angina and normal coronaries. But its correlation with inducible ischemia and prognostic significance in predicting future cardiovascular events has not been studied. The present study assessed the prognostic significance of CSFT during one year of follow up.

METHODS

We compared coronary sinus filling time of patients with angina and normal coronaries with that of control population. Control group was formed by those patients with supraventricular arrhythmia undergoing radiofrequency ablation and having normal coronaries. Baseline treadmill test (TMT) parameters like workload, duration and Duke Score were assessed. Patients were followed up for one year and a composite of cardiovascular mortality and non-fatal myocardial infarction was analyzed. Number of patients presenting to emergency or outpatient department with recurrent chest pain symptoms during one year follow up was considered for secondary outcome analysis. Coronary sinus filling time was analyzed with respect to cardiovascular events, repeat hospitalization for recurrent angina and TMT parameters.

RESULTS

Total 72 patients and 16 controls were studied. Mean CSFT value in the study group was 5.31 ± 1.03 sec and in the control group was 4.16 ± 0.72 sec and the difference was significant (p value = 0.0001). No correlation was found between baseline and repeat TMT parameters with CSFT. There was no cardiovascular mortality or hospitalization for non-fatal MI during one year follow up. But patients with frequent emergency or outpatient department visits with chest pain had a high CSFT compared with asymptomatic patients (p value = 0.005).

CONCLUSION

Coronary sinus filling time may be used as a simple marker of microvascular dysfunction in patients with angina and normal coronaries. Patients with recurrent chest pain symptoms after one year follow up were found to have high CSFT compared to asymptomatic patients.

Positional desaturation due to persistent left superior vena cava draining into the left atrium

Persistent left superior vena cava (PLSVC) is a rare congenital anomaly whose prevalence is 0.3 % of general population. The majority of PLSVC drain into right atrium (RA) through the coronary sinus without clinical harm. However, in about 10 % of patients with PLSVC, it drains into left atrium (LA) causing right-to-left shunt. Here, we present a 60-year-old male patient with a PLSVC draining into LA, who developed dyspnea and desaturation depending on the body position after trans-catheter coil embolization of coronary to pulmonary artery fistulas. PLSVC draining into LA should be included in the differential diagnosis of positional desaturation.

Quantitative assessment of synchronization during atrial fibrillation based on a novel index

Atrial Fibrillation (AF), a chaotic rhythm classically considered with random electrical activity, is now demonstrated to show a certain degree of organization and synchronization. Rather than those traditional indices which always focus on the pairwise properties of adjacent signals, a new synchronization index-S estimator-is introduced in this paper to quantify the synchronization level for all the signals in a selected area. By evaluating a complement of the entropy of the normalized eigenvalues of the corresponding correlation matrix, S estimator is designed to be proportional to the amount of synchronization. 400 episodes of 64-channel epicardial signals acquired from four living mongrels were studied under normal sinus rhythm (SN) and AF. The results showed that there were significant decreases of S estimator for both anterior left atrium and anterior right atrium with the rhythm changing from SN to AF. After dividing the research area into eight subparts, S estimator is also capable to demonstrate the different synchronization level for each subpart and revealed the electrophysiology individual difference among four experimental subjects. In conclusion, S estimator succeeds in estimating the synchronization degree for multi-channel signals in a selected area, with no limits to the number of the signals to be analyzed. It can help us to distinguish the region with a high synchronization level during AF, which would be helpful to the clinical AF treatment and enhance our understanding of underlying mechanisms of AF.

Speckle-tracking echocardiography elucidates the effect of pacing site on left ventricular synchronization in the normal and infarcted rat myocardium

Background

Right ventricular (RV) pacing generates regional disparities in electrical activation and mechanical function (ventricular dyssynchrony). In contrast, left ventricular (LV) or biventricular (BIV) pacing can improve cardiac efficiency in the setting of ventricular dyssynchrony, constituting the rationale for cardiac resynchronization therapy (CRT). Animal models of ventricular dyssynchrony and CRT currently relay on large mammals which are expensive and not readily available to most researchers. We developed a methodology for double-site epicardial pacing in conscious rats. Here, following post-operative recovery, we compared the effects of various pacing modes on LV dyssynchrony in normal rats and in rats with ischemic cardiomyopathy.

Methods

Two bipolar electrodes were implanted in rats as follows: Group A (n = 6) right atrial (RA) and RV sites; Group B (n = 7) RV and LV sites; Group C (n = 8) as in group B in combination with left coronary artery ligation. Electrodes were exteriorized through the back. Following post-operative recovery, two-dimensional transthoracic echocardiography was performed during pacing through the different electrodes. Segmental systolic circumferential strain (Ecc) was used to evaluate LV dyssynchrony.

Results

In normal rats, RV pacing induced marked LV dyssynchrony compared to RA pacing or sinus rhythm, as measured by the standard deviation (SD) of segmental time to peak Ecc, SD of peak Ecc, and the average delay between opposing ventricular segments. LV pacing and, to a greater extend BIV pacing diminished the LV dyssynchrony compared to RV pacing. In rats with extensive MI, the effects of LV and BIV pacing were markedly attenuated, and the response of individual animals was variable.

Conclusions

Rodent cardiac pacing mimics important features seen in humans. This model may be developed as a simple new tool to study the pathophysiology of ventricular dyssynchrony and CRT.

Assessment of global myocardial perfusion reserve using cardiovascular magnetic resonance of coronary sinus flow at 3 Tesla

BACKGROUND

Despite increasing clinical use, there is limited data regarding regadenoson in stress perfusion cardiovascular magnetic resonance (CMR). In particular, given its long half-life the optimal stress protocol remains unclear. Although Myocardial Perfusion Reserve (MPR) may provide additive prognostic information, current techniques for its measurement are cumbersome and challenging for routine clinical practice.The aims of this study were: 1) To determine the feasibility of MPR quantification during regadenoson stress CMR by measurement of Coronary Sinus (CS) flow; and 2) to investigate the role of aminophylline reversal during regadenoson stress-CMR.

METHODS

117 consecutive patients with possible myocardial ischemia were prospectively enrolled. Perfusion imaging was performed at 1 minute and 15 minutes after administration of 0.4 mg regadenoson. A subgroup of 41 patients was given aminophylline (100 mg) after stress images were acquired. CS flow was measured using phase-contrast imaging at baseline (pre CS flow), and immediately after the stress (peak CS flow) and rest (post CS flow) perfusion images.

RESULTS

CS flow measurements were obtained in 92% of patients with no adverse events. MPR was significantly underestimated when calculated as peak CS flow/post CS flow as compared to peak CS flow/pre CS flow (2.43±0.20 vs. 3.28±0.32, p=0.03). This difference was abolished when aminophylline was administered (3.35±0.44 vs. 3.30±0.52, p=0.95). Impaired MPR (peak CS flow/pre CS flow<2) was associated with advanced age, diabetes, current smoking and higher Framingham risk score.

CONCLUSIONS

Regadenoson stress CMR with MPR measurement from CS flow can be successfully performed in most patients. This measurement of MPR appears practical to perform in the clinical setting. Residual hyperemia is still present even 15 minutes after regadenoson administration, at the time of resting-perfusion acquisition, and is completely reversed by aminophylline. Our findings suggest routine aminophylline administration may be required when performing stress CMR with regadenoson.

Persistent left superior vena cava in cardiac congenital surgery

Persistent left superior vena cava (LSVC) is a relatively frequent finding in congenital cardiac malformation. The scope of the study was to analyze the timing of diagnosis of persistent LSVC, the timing of diagnosis of associated anomalies of the coronary sinus, and the global impact on morbidity and mortality of persistent LSVC in children with congenital heart disease after cardiac surgery. Retrospective analysis of a cohort of children after cardiac surgery on bypass for congenital heart disease. Three hundred seventy-one patients were included in the study, and their median age was 2.75 years (IQR 0.65-6.63). Forty-seven children had persistent LSVC (12.7 %), and persistent LSVC was identified on echocardiography before surgery in 39 patients (83 %). In three patients (6.4 %) with persistent LSVC, significant inflow obstruction of the left ventricle developed after surgery leading to low output syndrome or secondary pulmonary hypertension. In eight patients (17 %), persistent LSVC was associated with a partially or completely unroofed coronary sinus and in two cases (4 %) with coronary sinus ostial atresia. Duration of mechanical ventilation was significantly shorter in the control group (1.2 vs. 3.0 days, p = 0.04), whereas length of stay in intensive care did not differ. Mortality was also significantly lower in the control group (2.5 vs. 10.6 %, p = 0.004). The results of study show that persistent LSVC in association with congenital cardiac malformation increases the risk of mortality in children with cardiac surgery on cardiopulmonary bypass. Recognition of a persistent LSVC and its associated anomalies is mandatory to avoid complications during or after cardiac surgery.

Sex-specific assessment of reduced coronary sinus flow in non-hypertensive patients with coronary artery disease at rest

BACKGROUND

Access to data on the coronary flow in the coronary sinus (CS) can aid in the diagnosis of coronary artery disease (CAD). We tested the hypothesis that assessing the CS flow by transthoracic Doppler echocardiography (TTE) at rest can detect coronary artery stenosis in non-hypertensive patients.

METHODS

The antegrade phase of coronary flow in the CS was analyzed and compared in 140 male and 135 female non-hypertensive subjects who had all undergone coronary angiography.

RESULTS

There were statistically significant differences noted between males and females for the CS flow both in normal subjects and patients with CAD. Compared with normal subjects, patients with CAD had significantly lower blood flow in the CS both in males (196.6±174.31 vs. 367.65±168.04 ml/min, P<0.01) and females (183.04±65.46 vs. 244.13±135.43 ml/min P<0.01). For males, the diagnostic sensitivity, specificity, and accuracy of the cutoff value of the CS flow (206 ml/min) for predicting a significant coronary artery stenosis (>70%) were 91.67%, 81.25%, and 85.71%, respectively. For females, those of the cutoff value of the CS flow (195 ml/min) were 85.71%, 75%, and 80%, respectively.

CONCLUSION

TTE can effectively detect coronary hemodynamically significant stenosis in non-hypertensive male and female patients at different cutoff values.

Coronary sinus pacing for the management of right ventricular and atrial infarction with isolated right ventricular pulsus alternans

WEBSITE FEATURE

Modest elevation in BNP in asymptomatic hypertensive patients reflects sub-clinical cardiac remodeling, inflammation and extracellular matrix changes

In asymptomatic subjects B-type natriuretic peptide (BNP) is associated with adverse cardiovascular outcomes even at levels well below contemporary thresholds used for the diagnosis of heart failure. The mechanisms behind these observations are unclear. We examined the hypothesis that in an asymptomatic hypertensive population BNP would be associated with sub-clinical evidence of cardiac remodeling, inflammation and extracellular matrix (ECM) alterations. We performed transthoracic echocardiography and sampled coronary sinus (CS) and peripheral serum from patients with low (n = 14) and high BNP (n = 27). Peripheral BNP was closely associated with CS levels (r = 0.92, p<0.001). CS BNP correlated significantly with CS levels of markers of collagen type I and III turnover including: PINP (r = 0.44, p = 0.008), CITP (r = 0.35, p = 0.03) and PIIINP (r = 0.35, p = 0.001), and with CS levels of inflammatory cytokines including: TNF-α (r = 0.49, p = 0.002), IL-6 (r = 0.35, p = 0.04), and IL-8 (r = 0.54, p<0.001). The high BNP group had greater CS expression of fibro-inflammatory biomarkers including: CITP (3.8±0.7 versus 5.1±1.9, p = 0.007), TNF-α (3.2±0.5 versus 3.7±1.1, p = 003), IL-6 (1.9±1.3 versus 3.4±2.7, p = 0.02) and hsCRP (1.2±1.1 versus 2.4±1.1, p = 0.04), and greater left ventricular mass index (97±20 versus 118±26 g/m², p = 0.03) and left atrial volume index (18±2 versus 21±4, p = 0.008). Our data provide insight into the mechanisms behind the observed negative prognostic impact of modest elevations in BNP and suggest that in an asymptomatic hypertensive cohort a peripheral BNP measurement may be a useful marker of an early, sub-clinical pathological process characterized by cardiac remodeling, inflammation and ECM alterations.

Assessment of coronary flow reserve in the coronary sinus by cine 3T-magnetic resonance imaging in young adults after surgery for tetralogy of Fallot

This study aimed to evaluate CFR by assessing blood flow in the coronary sinus and systemic endothelial function measured by FMD of the brachial artery in an open prospective study of 10 control subjects and 10 patients (ages, 15-25 years) who have undergone surgical TOF repair. Reduced ventricular function, impaired exercise capacity, and ventricular arrhythmia have been proposed as risk factors for sudden cardiac death after surgical repair of TOF. Some of this may be related to impaired myocardial perfusion. A 3.0T GE Signa Excite scanner was used to achieve phase-contrast, velocity-encoding cine magnetic resonance imaging in the coronary sinus before and during infusion with adenosine (0.14 mg/kg/min). FMD was measured in the brachial artery before arterial occlusion and 5 min afterward. The TOF group demonstrated significantly higher volumetric blood flow in the coronary sinus (282 ± 63 ml/min) than the normal control subjects at rest (184 ± 57 ml/min) (P = 0.006). During adenosine infusion, this difference disappeared. The CFR was 2.00 ± 0.43 in the control group and 1.19 ± 0.34 in the TOF group (P = 0.002). No correlation between FMD and CFR was observed in the study group (r (s) = 0.61, n = 8, P = 0.15). This study showed a reduced CFR due to a higher blood flow of the subject at rest in the TOF group. This reduced CFR may disable a normal adaptation to increased oxygen demand during exercise and increase myocardial vulnerability to reduced blood supply postoperatively for TOF patients with coronary heart disease.

Congenital absence of right superior vena cava: a "stomach" within the heart

WEBSITE FEATURE

Local coronary flow is associated with an unsuccessful complete block line at the mitral isthmus in patients with atrial fibrillation

BACKGROUND

The addition of a mitral isthmus (MI) block line after pulmonary vein isolation could lead to a favorable outcome of catheter ablation in patients with atrial fibrillation (AF). However, it is sometimes tough to create a complete MI block line, and the cooling effect because of the local coronary flow may prevent the creation of a successful MI block line.

METHODS AND RESULTS

This study enrolled 81 AF patients in whom the creation of an MI block line was attempted in those with persistent or pacing-inducible AF after pulmonary vein isolation. A local coronary artery (LCA) across the MI block line was observed in 43 (53%) of 81 patients, and a bidirectional MI block was successfully accomplished in 53 (65%) of 81 patients, at the estimated MI line. The ratio of a successful MI block line was significantly lower in the patients with an LCA than in those without an LCA (42% versus 92%; P<0.001). The mean diameter of the coronary sinus (0.59 ± 0.18 versus 0.82 ± 0.22 cm; P<0.001) and length of the estimated MI line (33.4 ± 9.9 versus 29.4 ± 7.1 mm; P=0.032) were significantly shorter in the patients with a successful MI block line than in those without a successful MI block line. In the multivariable analysis, an LCA at the MI and a larger coronary sinus diameter were independent risk factors for an unsuccessful MI block line.

CONCLUSIONS

Local coronary flow at the MI is associated with an increased incidence of an unsuccessful MI block line.

Electrical activation in the coronary sinus branches as a guide to cardiac resynchronisation therapy: rationale for a coordinate system

BACKGROUND

For successful cardiac resynchronisation therapy (CRT) a spatial and electrical separation of right and left ventricular electrodes is essential. The spatial distribution of electrical delays within the coronary sinus (CS) tributaries has not yet been identified.

OBJECTIVE

Electrical delays within the CS are described during sinus rhythm (SR) and right ventricular pacing (RVP). A coordinate system grading the mitral ring from 0° to 360° and three vertical segments is proposed to define the lead positions irrespective of individual CS branch orientation.

METHODS

In 13 patients undergoing implantation of a CRT device 6±2.5, (median 5) lead positions within the CS were mapped during SR and RVP. The delay to the onset and the peak of the local signal was measured from the earliest QRS activation or the pacing spike. Fluoroscopic positions were compared to localizations on a nonfluoroscopic electrode imaging system.

RESULTS

During SR, electrical delays in the CS were inhomogenous in patients with or without left bundle branch block (LBBB). During RVP, the delays increased by 44±32 ms (signal onset from 36±33 ms to 95±30 ms; p<0.001, signal peak from 105±44 ms to 156±30 ms; p<0.001). The activation pattern during RVP was homogeneous and predictable by taking the grading on the CS ring into account: (% QRS) = 78-0.002 (grade-162)(2), p<0.0001. This indicates that 78% of the QRS duration can be expected as a maximum peak delay at 162° on the CS ring.

CONCLUSION

Electrical delays within the CS vary during SR, but prolong and become predictable during RVP. A coordinate system helps predicting the local delays and facilitates interindividual comparison of lead positions irrespective of CS branch anatomy.

Retrograde coronary sinus cardioplegia cannula placement under short-time circulatory arrest in surgery for a ruptured type A dissection with a previous coronary artery bypass

A 79-year-old woman was referred to undergo surgery for a type A dissection. The patient had a history of previous coronary artery bypass. She was in shock and had a hematoma surrounding the ascending aorta and the heart. In this case, a coronary sinus cardioplegia cannula was placed under a short period of circulatory arrest via a small atriotomy, and the atriotomy was closed immediately to establish selective cerebral perfusion.

Absence of left atrium-coronary sinus musculature electrical connection at coronary sinus ostium unmasked by unique double coronary sinus potentials pattern

We describe a 77-year-old man with Wolff-Parkinson-White syndrome exhibiting double coronary sinus (CS) potentials during retrograde conduction over accessory pathway (AP). The first, low-frequency potential (DP1) was first recorded in the left posterolateral region, while the second, higher frequency signal (DP2) was recorded in a lateral-to-septal direction. The two signals were fused near the left lateral wall. Successful ablation of the AP was obtained at its ventricular insertion site in the postero-septal region. The unexpectedly delayed activation of the paraseptal RA following activation of the paraseptal left atrium (DP1) can be explained by the absence of a LA-CS musculature (CSM) electrical connection at the proximal CS, which forces a detour of the activation wavefront from LA to RA via the distal CS (DP2). This is a rare case exhibiting unique double CS potentials which unmasked the absence of a LA-CSM electrical connection at CS ostium.

Typical atrial flutter with atypical flutter wave morphology due to abnormal interatrial conduction

We report a case of typical counterclockwise atrial flutter (AFL) with conduction block from right to left atrium along the coronary sinus (CS) musculature, confirmed by discontinuous CS activation sequence during pacing near the ostium and differential right atrial pacing. AFL was associated with an atypical flutter wave morphology, due to the detour of the activation wavefront from right to left atrium via alternate interatrial electrical connections, such as Bachmann's bundle, the interatrial septum, or both.

Characterization of the mechanical properties of the coronary sinus for percutaneous transvenous mitral annuloplasty

The coronary sinus (CS) vessel serves as a conduit for the deployment of percutaneous transvenous mitral annuloplasty (PTMA) devices for the treatment of functional mitral regurgitation. Characterization of the mechanical response of the CS is an important step towards an understanding of tissue-device interaction in PTMA intervention. The purpose of this study was to investigate the mechanical properties of the porcine CS using the pressure-inflation test and constitutively model the wall behavior using a four fiber family strain energy function (SEF). The results showed that the CS exhibited an S-shaped pressure-radius response and could be dilated up to 88% at a pressure of 80mmHg. Excellent results from model fitting indicated that the four fiber family SEF could capture the experimental data well and could be used in future numerical simulations of tissue-device interaction. In addition, a histological study was performed to identify the micro-structure of the CS wall. We found a high content of striated myocardial fibers (SMFs) surrounding the CS wall, which was also mainly composed of SMFs, while the content of smooth muscle cells was very low. Elastin and collagen fibers were highly concentrated in the luminal and outer layers and sparsely distributed in the medial layer of the CS wall. These structural and mechanical properties of the CS should be taken into consideration in future PTMA device designs.

Comparison of serum troponin I and plasma lactate concentrations in arrested versus beating-heart aortic valve replacement

BACKGROUND AND AIM OF THE STUDY

The study aim was to monitor serum troponin and plasma lactate concentrations in conventional aortic valve replacement compared to a beating-heart technique, perfused via the coronary sinus.

METHODS

In this prospective, non-randomized study, which was conducted between 2003 and 2009, a total of 35 patients was allocated to two groups, based on the method of myocardial protection. The groups did not differ significantly in terms of preoperative parameters. Levels of lactate were measured in all 35 patients, and of troponin I in 20 patients, in consecutive samples during and after surgery.

RESULTS

There was no in-hospital mortality and no serious complications among patients. The cardiopulmonary bypass and aortic cross-clamp times were each significantly shorter and lactate and troponin I concentrations higher, in the beating-heart group. No perioperative myocardial infarction was observed.

CONCLUSION

Although good clinical results were observed in patients operated when using the beating-heart technique with retrograde coronary sinus perfusion, postoperative serum levels of troponin I were higher than in patients operated on using a conventional technique. Although troponin I is considered a prognostic factor for postoperative mortality, this parameter applies only to selected patients rather than for widespread use.

Atypical atrioventricular nodal reentry tachycardia with eccentric retrograde left-sided activation of coronary sinus

BACKGROUND

Recent anatomical and electrophysiological studies have demonstrated that in the human atrioventricular node there are two main extensions, the rightward and leftward posterior nodal extension (LPNE). The occurrence of eccentric retrograde atrial activation has been demonstrated in several previous reports to be from 6 to 8% in patients with AVNRT.

OBJECTIVES

The study was performed to confirm that standard right atrium ablation is effective and successful for atrioventricular node reentry tachycardia (AVNRT) with eccentric retrograde left-sided activation, masquerading as a tachycardia which looks like a tachycardia, using the left accessory pathway.

METHODS AND RESULTS

During a 7 years period (from 2002 to 2008), 865 consecutive patients underwent electrophysiological study. In the group with atrioventricular node reentry tachycardia (AVNRT) there were 178 patients. In the group with typical fast-slow AVNRT (162 pts) there was concentric retrograde activation of both the atria. The 16 patients had atypical AVNRT (10 pts with slow-slow AVNRT and 6 pts with LPNE). The ablation was performed, in all patients in the Koch's triangle on the slow pathway of the atrioventricular node. The successful rate of ablation was 99.4% (177/178 pts). The incidence of AVNRT with eccentric retrograde activation was 3.4%. In the follow-up period (16±12 months), there was no recurrence of AVNRT in the group with LPNE.

CONCLUSIONS

This study demonstrated the different electrophysiologic characteristics between the AVNRT patients with eccentric and concentric retrograde atrial activation. Standard ablation, but a little bit higher in the Koch's triangle, closer to the fast pathway, in the right atrium is effective and successful for AVNRT with retrograde left eccentric conduction in the coronary sinus.

[Venous system of the heart in chronic heart failure]

The intravital and posthumous changes of the venous system of the heart were studied in patients with chronic heart failure (CHF). Using the method of computer spiral tomography, the increase of the diameter of subepicardial and anterior cardiac veins, as well as of the coronary sinus, was detected that correlated with the stages of heart failure development. The increase of a total thickness of the veins wall at the expense of tunica media was recorded at the initial stages of CHF, which was later followed by the decrease of wall thickness due to the development of connective tissue.

[Modification of coronary sinus in patients with chronic cardiac insufficiency]

Both venous and arterial beds undergo a number of morphofunctional changes in patients with cardiovascular pathology, but they rarely attract attention of researchers. The available data indicate that the cardiac venous system (CVS) plays an important role in the development of chronic cardiac insufficiency (CCI) and dictate the necessity of its in-depth studies. We examined CVS in 160 patients by Doppler echo-CG and in 41 ones by spiral CT. The patients were allocated to 3 groups depending on the stage of CCI (IIA, IIB and III stages, III-IV functional class). The state of their coronary sinus (CS) was compared with that of healthy subjects. The state of CS varied considerably depending on the stage of CCI. It is concluded that patients with CCI need their CVS to be studied by all available methods.

Implementing cardiac resynchronization therapy in routine clinical practice: preoperative considerations and implantation techniques

Cardiac resynchronization therapy (CRT) using coronary sinus (CS) leads is an established therapy for congestive heart failure in patients with asynchronous ventricular contractions. CRT improves not only exercise tolerance but also the patient's prognosis. Appropriate patient selection for CRT is essential for a successful therapeutic response. Inclusion criteria are based on symptoms (New York Heart Association classes III and IV), a reduced ejection fraction, and a widened QRS complex. The presence of objective markers of heart failure can be considered a prerequisite for successful CRT. CRT procedures are much longer than regular pacemaker implantations, and thus the risk of infection may be greater. Successful therapy depends on the placement of left ventricular leads, usually via the CS, which is a technically more challenging procedure than regular pacemaker implantations. Complications specific to CRT include ventricular arrhythmia, such as ventricular tachycardia or ventricular fibrillation; total atrioventricular block or sinus arrest without any escape rhythm; and CS dissection.

Randomized Evaluation of Right Atrial Ablation After Left Atrial Ablation of Complex Fractionated Atrial Electrograms for Long-Lasting Persistent Atrial Fibrillation

Background— With electrogram-guided radiofrequency ablation (RFA) of long-lasting persistent atrial fibrillation (AF), the best results have been reported when complex fractionated electrograms (CFAEs) in both the left (LA) and right (RA) atria were targeted. However, many studies have reported excellent outcomes from RFA of long-lasting persistent AF with the use of other ablation strategies that were limited to the LA. The incremental value of RFA of RA CFAEs is yet to be defined.

Methods and Results— In 85 patients with long-lasting persistent AF (age=59�10 years), RFA was directed at CFAEs in the LA and coronary sinus until AF terminated (19) or all identified LA CFAEs were eliminated. Sixty-six patients who remained in AF were randomly assigned to cardioversion and no further RFA (n=33) or to RFA of RA CFAEs (n=33). RA sites consisted of the crista terminalis (69%), septum (38%), superior vena cava (28%), coronary sinus ostium (22%), and the base of the appendage (31%). AF terminated in 1 (3%) of 33 patients during RA RFA. At 17�6 months after a single ablation procedure, 74% of the patients in whom AF terminated during LA RFA were in sinus rhythm. Rates of freedom from AF were similar in the patients randomized to no RFA in the RA (24%) and those randomized to RFA of RA CFAEs (30%, P =0.8). The ablation procedure was repeated in 26 patients (31%) for AF (n=22) or atrial flutter (n=4). At 16�7 months after the final procedure, 89% of the patients in whom AF terminated during LA RFA were in sinus rhythm. Among the randomized patients, the proportion of patients who remained in sinus rhythm was similar in patients who did not undergo RFA of RA CFAEs (52%) and those who did (58%, P =0.6).

Conclusion— After RFA of CFAEs in the LA and coronary sinus, ablation of CFAEs in the RA provides little or no increment in efficacy among patients with long-lasting persistent AF.

Early septal activation, successful lateral ablation

The coronary sinus activation pattern is an important clue for the detection of arrhythmia mechanisms and/or localization of accessory pathways. Any change in this pattern during radiofrequency ablation should be evaluated carefully to recognize the presence of another accessory pathway or innocence of the accessory pathway during arrhythmia. Intra-atrial conduction block can change the coronary sinus activation pattern. Negligence regarding this phenomenon can cause irreversible complications. Here we describe a case with left lateral accessory pathway conduction in which intra-atrial conduction block completely reversed the coronary sinus activation pattern.