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Zeitschrift Fur Kardiologie Aug 1975Recently disorders of sinus node function have found increasing interest in clinical medicine thanks to new diagnostic and therapeutic developments. This paper... (Review)
Review
Recently disorders of sinus node function have found increasing interest in clinical medicine thanks to new diagnostic and therapeutic developments. This paper represents a comprehensive review of these conditions, combined under the name "Sick Sinus Syndrome" (SSS). Besides a detailed analysis of 63 cases seen at our institution, the results of other groups are compared and extensively discussed. The clinical picture of the SSS is characterized by a wide variety of bradycardiac and tachycardic atrial arrhythmias, occurring separately or in combination. These can be classified in three subgroups: Patients with exclusive sinus bradycardia; patients with sinoatrial exit block or transient episodes of sinus arrest with or without AV escape rhythms; and finally patients with the bradycardia/tachycardia-syndrome, which are complicated by additional atrial tachyarrhythmias. The symptomatology of the SSS is multiform and extends from symptomless cases and those with only general signs of reduced cardiac function to patients with recurrent severe syncopal attacks which may lead to cerebral damage and even death. Besides the typical history, the diagnosis of the SSS primarily rests upon the ECG, especially the long term ECG recorded continuously on a 24 hrs. tape (Holter technique). Also the exercise ECG is of some value, characteristically showing an inadequate increase in the sinus rate, sometimes with AV escape systoles and -rhythms. In addition various provocative tests have been devised which are of help to differentiate between a pathologic and a normal sinus node function. Among these the determination of the sinus node recovery time following overdrive atrial pacing has gained wide acceptance. In most cases the exact etiology of the SSS is not known. In addition to coronary and inflammatory heart diseases a primarily degenerative lesion of the sinus node, comparable to cases with "primary heart block" are discussed. There is also a remarkably frequent past history diththeria. Rarer causes of the condition represent cases with cardiomyopathy, thyreotoxic heart disease, collagen and other disorders and also a familial manifestation of the SSS has been described. Therapeutically, pharmacologic treatment with vagolytic, beta-adrenergic or the common antiarrhythmic drugs is often unsuccessful, especially in the treatment of the Brady-Tachy-Syndrome. Digitalis glycosides, however, are frequently of some value, as they represent an effective prophylactic agent against atrial tachyarrhythmias without prolonging the sinus node recovery time or reducing significantly the sinus rate. While a few patients do not require any treatment, an artificial cardiac pacemaker has to be inserted in most cases. Atrial stimulation may be superior to ventricular on-demand pacing in some patients, and also a special system for the treatment of the SSS combined with significant AV block (binodal disease) has been designed, the bifocal sequential pacemaker.
Topics: Age Factors; Aged; Arrhythmias, Cardiac; Atrial Flutter; Atropine; Bradycardia; Chronic Disease; Coronary Disease; Electrocardiography; Exercise Test; Female; Heart Rate; Humans; Hyperthyroidism; Male; Middle Aged; Prognosis; Rheumatic Fever; Sex Factors; Sinoatrial Node; Syncope; Tachycardia
PubMed: 1099830
DOI: No ID Found -
Pulmonary Therapy Jun 2022Cystic fibrosis (CF) is due to a mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which leads to unusual water and chloride secretion... (Review)
Review
Cystic fibrosis (CF) is due to a mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which leads to unusual water and chloride secretion across epithelial surfaces. The lungs are responsible for most morbidity, though other organs are frequently affected. Sleep abnormalities have long been recognized in CF. Abnormal ventilation and oxygenation, sinus disease, deconditioning due to muscle weakness and recurrent infections, and inflammation have been thought to play a role in sleep disorders in CF. However, there is evidence that CFTR gene dysregulation can affect circadian rhythms in CF. Early recognition and treatment of circadian rhythms may improve outcomes in CF.
PubMed: 35149967
DOI: 10.1007/s41030-022-00184-x -
The Journal of Physiology May 2016Sudden cardiac death (SCD) is the result of a change of cardiac activity from normal (typically sinus) rhythm to a rhythm that does not pump adequate blood to the brain.... (Review)
Review
Sudden cardiac death (SCD) is the result of a change of cardiac activity from normal (typically sinus) rhythm to a rhythm that does not pump adequate blood to the brain. The most common rhythms leading to SCD are ventricular tachycardia (VT) or ventricular fibrillation (VF). These result from an accelerated ventricular pacemaker or ventricular reentrant waves. Despite significant efforts to develop accurate predictors for the risk of SCD, current methods for risk stratification still need to be improved. In this article we briefly review current approaches to risk stratification. Then we discuss the mathematical basis for dynamical transitions (called bifurcations) that may lead to VT and VF. One mechanism for transition to VT or VF involves a perturbation by a premature ventricular complex (PVC) during sinus rhythm. We describe the main mechanisms of PVCs (reentry, independent pacemakers and abnormal depolarizations). An emerging approach to risk stratification for SCD involves the development of individualized dynamical models of a patient based on measured anatomy and physiology. Careful analysis and modelling of dynamics of ventricular arrhythmia on an individual basis will be essential in order to improve risk stratification for SCD and to lay a foundation for personalized (precision) medicine in cardiology.
Topics: Animals; Arrhythmias, Cardiac; Death, Sudden, Cardiac; Heart Ventricles; Humans; Risk Factors
PubMed: 26660287
DOI: 10.1113/JP270535 -
Frontiers in Cardiovascular Medicine 2022Low-voltage-substrate (LVS)-guided ablation for persistent atrial fibrillation (AF) has been described either in sinus rhythm (SR) or AF. Prolonged fractionated...
BACKGROUND
Low-voltage-substrate (LVS)-guided ablation for persistent atrial fibrillation (AF) has been described either in sinus rhythm (SR) or AF. Prolonged fractionated potentials (PFPs) may represent arrhythmogenic slow conduction substrate and potentially co-localize with LVS. We assess the spatial correlation of PFP identified in AF (PFP-AF) to those mapped in SR (PFP-SR). We further report the relationship between LVS and PFPs when mapped in AF or SR.
MATERIALS AND METHODS
Thirty-eight patients with ablation naïve persistent AF underwent left atrial (LA) high-density mapping in AF and SR prior to catheter ablation. Areas presenting PFP-AF and PFP-SR were annotated during mapping on the LA geometry. Low-voltage areas (LVA) were quantified using a bipolar threshold of 0.5 mV during both AF and SR mapping. Concordance of fractionated potentials (CFP) (defined as the presence of PFPs in both rhythms within a radius of 6 mm) was quantified. Spatial distribution and correlation of PFP and CFP with LVA were assessed. The predictors for CFP were determined.
RESULTS
PFPs displayed low voltages both during AF (median 0.30 mV (Q1-Q3: 0.20-0.50 mV) and SR (median 0.35 mV (Q1-Q3: 0.20-0.56 mV). The duration of PFP-SR was measured at 61 ms (Q1-Q3: 51-76 ms). During SR, most PFP-SRs (89.4 and 97.2%) were located within LVA (<0.5 mV and <1.0 mV, respectively). Areas presenting PFP occurred more frequently in AF than in SR (median: 9.5 vs. 8.0, = 0.005). Both PFP-AF and PFP-SR were predominantly located at anterior LA (>40%), followed by posterior LA (>20%) and septal LA (>15%). The extent of LVA < 0.5 mV was more extensive in AF (median: 25.2% of LA surface, Q1-Q3:16.6-50.5%) than in SR (median: 12.3%, Q1-Q3: 4.7-29.4%, = 0.001). CFP in both rhythms occurred in 80% of PFP-SR and 59% of PFP-AF ( = 0.008). Notably, CFP was positively correlated to the extent of LVA in SR ( = 0.004), but not with LVA in AF ( = 0.226). Additionally, the extent of LVA < 0.5 mV in SR was the only significant predictor for CFP, with an optimal threshold of 16% predicting high (>80%) fractionation concordance in AF and SR.
CONCLUSION
Substrate mapping in SR vs. AF reveals smaller areas of low voltage and fewer sites with PFP. PFP-SR are located within low-voltage areas in SR. There is a high degree of spatial agreement (80%) between PFP-AF and PFP-SR in patients with moderate LVA in SR (>16% of LA surface). These findings should be considered when substrate-based ablation strategies are applied in patients with the left atrial low-voltage substrate with recurrent persistent AF.
PubMed: 36330001
DOI: 10.3389/fcvm.2022.1000027 -
Circulation Research Jul 1985Sinus node recovery time was compared to the recovery time of a slow atrioventricular junctional rhythm in each of the same seven pentobarbital anesthetized dogs....
Sinus node recovery time was compared to the recovery time of a slow atrioventricular junctional rhythm in each of the same seven pentobarbital anesthetized dogs. Recovery time and the first five cardiac cycles were examined after pacing atria and ventricles for 20, 40, and 60 seconds at four or more pacing cycle lengths. Data relating recovery times and return to control conditions to prepacing cycle length, pacing cycle length, duration of pacing, site of pacing, and origin of rhythms were analyzed by covariance analysis. From the analyses, the relative contribution of the determinants are: the prepacing cycle length 73%, the site of pacing 3.5%, the pacing cycle length 2%, and the interaction of the site of pacing and pacing cycle length 1% for sinus node recovery time; and for slow atrioventricular junctional rhythm recovery time, the duration of pacing 40%, the interactions between the duration of pacing and the pacing cycle length 27%, and the prepacing cycle length 9%. A modified exponential decay model predicted 8 beats for return to prepacing conditions during sinus rhythm and 66-100 beats during atrioventricular junctional rhythm. We conclude that the single most important determinant of sinus node recovery time is the prepacing cycle length. Pacing cycle length and site of pacing have a significant but small influence on sinus node recovery time and duration of pacing, beyond 20 seconds, has no significant influence. In contrast, duration of pacing is the most important determinant of slow atrioventricular junctional recovery time. Another major determinant of slow atrioventricular junctional recovery time is the interactions between pacing cycle length and duration of pacing. Prepacing cycle length has a minor influence, and site of pacing has no influence, on slow atrioventricular junctional recovery time.
Topics: Animals; Atrioventricular Node; Cardiac Pacing, Artificial; Dogs; Electrocardiography; Female; Heart Atria; Heart Block; Heart Conduction System; Heart Rate; Heart Ventricles; Male; Sinoatrial Node
PubMed: 4006100
DOI: 10.1161/01.res.57.1.182 -
Journal of Cardiology Cases Oct 2022Despite recent advances in therapeutic approaches, treatment for patients with refractory protein-losing enteropathy (PLE) after undergoing the Fontan procedure remains...
UNLABELLED
Despite recent advances in therapeutic approaches, treatment for patients with refractory protein-losing enteropathy (PLE) after undergoing the Fontan procedure remains a challenge for clinicians. In this report, we present a Fontan patient in whom oral cilostazol improved PLE with a restored atrial rhythm. We report on a 13-year-old girl with double-outlet right ventricle, ventricular septal defect, l-transposition of the great arteries, and left ventricle hypoplasia. After the Fontan procedure at 16 months of age, she developed PLE at the age of 2 years. As medical treatments such as diuretics, enalapril, heparin, stent implantation for left pulmonary artery, and oral steroids did not lead to remission, intermittent albumin administration was needed. She had ectopic atrial and junctional rhythms, and cardiac catheterization revealed that the junctional rhythm decreased cardiac output and increased central venous pressure. We therefore started her on cilostazol and succeeded in the maintenance of atrial rhythm, resulting in increased serum albumin, globulin, electrolytes, and nutritional status markers with suppression of bowel inflammation. This patient finally was taken off the steroid and returned to a normal school and home life. Oral cilostazol is a possible therapeutic strategy for refractory PLE, as it improves hemodynamics in Fontan patients with sinus node dysfunction.
LEARNING OBJECTIVE
We present a Fontan patient in whom oral cilostazol for maintaining atrial rhythm improved protein-losing enteropathy (PLE) without any side effects. The junctional rhythm disappeared after the initiation of cilostazol, which suggested that cilostazol stimulated a dominant pacemaker even if the pacemaker was an ectopic focus in the atrium. Oral cilostazol is a possible therapeutic strategy for refractory PLE. We also propose oral cilostazol as a bridging therapy prior to pacemaker implantation.
PubMed: 36187315
DOI: 10.1016/j.jccase.2022.05.012 -
Equine Veterinary Journal Jul 2021Exercise-associated cardiac rhythm disturbances are common, but there is a lack of evidence-based criteria on which to distinguish clinically relevant rhythm...
BACKGROUND
Exercise-associated cardiac rhythm disturbances are common, but there is a lack of evidence-based criteria on which to distinguish clinically relevant rhythm disturbances from those that are not.
OBJECTIVES
To describe and characterise rhythm disturbances during clinical exercise testing; to explore potential risk factors for these rhythm disturbances and to determine whether they influenced future racing.
STUDY DESIGN
Retrospective cohort using a convenience sample.
METHODS
Medical records were reviewed from two clinical services to identify horses with poor performance and/or respiratory noise with both exercise endoscopy and electrocardiography results. Respiratory and ECG findings recorded by the attending clinicians were described, and for polymorphic ventricular rhythms (n = 12), a consensus team agreed the final rhythm characterisation. Several statistical models analysing risk factors were built and racing records were reviewed to compare horses with and without rhythm disturbance.
RESULTS
Of 245 racehorses, 87 (35.5%) had no ectopic/re-entrant rhythms, 110 (44.9%) had isolated premature depolarisations during sinus rhythm and 48 (19.6%) horses had complex tachydysrrythmias. Rhythm disturbances were detected during warm-up in 20 horses (8.2%); during gallop in 61 horses (24.9%) and during recovery in 124 horses (50.6%). Most complex rhythm events occurred during recovery, but there was one horse with a single couplet during gallop and another with a triplet during gallop. Fifteen horses (one with frequent isolated premature depolarisations and 14 complex rhythms) were considered by clinicians to be potentially contributing to poor performance. Treadmill exercise tests, the presence of exercise-associated upper respiratory tract obstructions and National Hunt racehorses were associated with rhythm disturbances. The proportion of horses racing again after diagnosis (82%) was similar in all groups and univariable analysis revealed no significant associations between subsequent racing and the presence of any ectopic/re-entrant rhythm, or the various sub-groups based on phase of exercise in which this was detected.
MAIN LIMITATIONS
Reliance on retrospective data collection from medical records with no control group. Exercise ECGs were collected using only 1 or 2 leads. Variables examined as risk factors could be considered to be inter-related and our sub-groups were small.
CONCLUSIONS
This study confirms a high prevalence of cardiac rhythm disturbances, including complex ectopic/re-entrant rhythms, in poorly performing racehorses. Detection of rhythm disturbances may vary with exercise test conditions and exercise-associated upper respiratory tract obstructions increase the risk of rhythm disturbances.
Topics: Animals; Arrhythmias, Cardiac; Electrocardiography; Horse Diseases; Horses; Physical Conditioning, Animal; Retrospective Studies; Risk Factors
PubMed: 32979227
DOI: 10.1111/evj.13354 -
Cardiology Research Aug 2023Low voltage areas (LVAs) have been proposed as surrogate markers for left atrial (LA) scar. Correlation between voltages in sinus rhythm (SR) and atrial fibrillation...
BACKGROUND
Low voltage areas (LVAs) have been proposed as surrogate markers for left atrial (LA) scar. Correlation between voltages in sinus rhythm (SR) and atrial fibrillation (AF) have previously been measured via point-by-point analysis. We sought to compare LA voltage composition measured in SR to AF, utilizing a high-density automated voltage histogram analysis (VHA) tool in those undergoing pulmonary vein isolation (PVI) for persistent AF (PeAF).
METHODS
We retrospectively analyzed patients with PeAF undergoing PVI. Maps required ≥ 1,000 voltage points in each rhythm and had a standardized procedure (mapped in AF then remapped in SR post-PVI). We created six anatomical segments (AS) from each map: anterior, posterior, roof, floor, septal and lateral AS. These were analyzed by VHA, categorizing atrial LVAs into 10 voltage aliquots 0 - 0.5 mV. Data were analyzed using SPSS v.26.
RESULTS
We acquired 58,342 voltage points (n = 10 patients, mean age: 67 ± 13 years, three females). LVA burdens of ≤ 0.2 mV, designated as "severe LVAs", were comparable between most AS (except on the posterior wall) with good correlation. Mapped voltages between the ranges of 0.21 and 0.5 mV were labeled as "diseased LA tissue", and these were found significantly more in AF than SR. Significant differences were seen on the roof, anterior, posterior, and lateral AS.
CONCLUSIONS
Diseased LA tissue (0.21 - 0.5 mV) burden is significantly higher in AF than SR, mainly in the anterior, roof, lateral, and posterior wall. LA "severe LVA" (≤ 0.2 mV) burden is comparable in both rhythms, except with respect to the posterior wall. Our findings suggest that mapping rhythm has less effect on the LA with voltages < 0.2 mV than 0.2 - 0.5 mV across all anatomical regions, excluding the posterior wall.
PubMed: 37559712
DOI: 10.14740/cr1503 -
Veterinary Journal (London, England :... Sep 2020The identification of the heart rhythm during an episode of transient loss of consciousness (TLOC) is considered the reference standard method to elucidate the...
The identification of the heart rhythm during an episode of transient loss of consciousness (TLOC) is considered the reference standard method to elucidate the underlying aetiology. This study aimed to characterise heart rhythm in dogs during TLOC using Holter and external loop recorder monitoring. We retrospectively reviewed 24-h Holter monitoring and external loop recorder tracings from 8084 dogs. Heart rhythms from dogs that experienced TLOC during the recording was analysed to identify rhythm disturbances that occurred during episodes of TLOC. Electrocardiograms (ECGs) were subsequently categorised into Type 1 (ventricular arrest), Type 2 (sinus bradycardia), Type 3 (no/slight rhythm variations), and Type 4 (tachycardia). Transient LOC was documented in 92 dogs over 230 episodes of TLOC. Percentage of cases with ECGs compatible with each classification were as follows: 72.1%, Type 1; 6.1%, Type 2; 20.9%, Type 3; and 0.9%, Type 4. Cardiac rhythm during the TLOC could have been a consequence of a neurocardiogenic mechanism in 46.7% cases, while intrinsic rhythm disturbances of the sinus node or of the atrioventricular node were diagnosed in 31.5% cases. In two cases, tachycardia was the possible cause of the TLOC. ECG patterns in dogs presenting with multiple TLOC episodes were completely reproducible during each episode. TLOC in dogs was primarily caused by ventricular arrest. Most dogs with TLOC had electrocardiographic finding suggestive of a reflex or neurally-mediated syncope, but one third had an ECG more suggestive of a conduction disorder. Distinguishing these two entities could help inform diagnostic, therapeutic, and prognostic plans.
Topics: Animals; Arrhythmias, Cardiac; Dog Diseases; Dogs; Electrocardiography; Electrocardiography, Ambulatory; Female; Heart Rate; Male; Retrospective Studies; Syncope; Unconsciousness
PubMed: 32928492
DOI: 10.1016/j.tvjl.2020.105523