Use of machine learning and Poincaré density grid in the diagnosis of sinus node dysfunction caused by sinoatrial conduction block in dogs.

BACKGROUND: Sinus node dysfunction because of abnormal impulse generation or sinoatrial conduction block causes bradycardia that can be difficult to differentiate from high parasympathetic/low sympathetic modulation (HP/LSM). HYPOTHESIS: Beat-to-beat relationships of sinus node dysfunction are quantifiably distinguishable by Poincaré plots, machine learning, and 3-dimensional density grid analysis. Moreover, computer modeling establishes sinoatrial conduction block as a mechanism. ANIMALS: Three groups of dogs were studied with a diagnosis of: (1) balanced autonomic modulation (n = 26), (2) HP/LSM (n = 26), and (3) sinus node dysfunction (n = 21). METHODS: Heart rate parameters and Poincaré plot data were determined [median (25%-75%)]. Recordings were randomly assigned to training or testing. Supervised machine learning of the training data was evaluated with the testing data. The computer model included impulse rate, exit block probability, and HP/LSM. RESULTS: Confusion matrices illustrated the effectiveness in diagnosing by both machine learning and Poincaré density grid. Sinus pauses >2 s differentiated (P < .0001) HP/LSM (2340; 583-3947 s) from sinus node dysfunction (8503; 7078-10 050 s), but average heart rate did not. The shortest linear intervals were longer with sinus node dysfunction (315; 278-323 ms) vs HP/LSM (260; 251-292 ms; P = .008), but the longest linear intervals were shorter with sinus node dysfunction (620; 565-698 ms) vs HP/LSM (843; 799-888 ms; P < .0001). CONCLUSIONS: Number and duration of pauses, not heart rate, differentiated sinus node dysfunction from HP/LSM. Machine learning and Poincaré density grid can accurately identify sinus node dysfunction. Computer modeling supports sinoatrial conduction block as a mechanism of sinus node dysfunction.

The Anatomical Substrate for Sick Sinus Syndrome in Dogs.

The hearts of 28 dogs, clinically diagnosed as having symptomatic sick sinus syndrome (SSS), were examined post mortem, with a particular focus on the sinus node (SN) region. The affected dogs were divided into two groups according to the findings of ambulatory electrocardiography: 16 dogs with severe sinoatrial (SA) block and/or sinus arrest (group A) and 12 dogs with long sinus or atrial pauses due to SA block and/or sinus arrest accompanied by atrial tachyarrhythmias (group B). The most significant histopathological changes found in both SSS groups were extensive destruction of the SN characterized by depletion of nodal cells with fatty or fibrofatty replacement and interruption of contiguity between the SN and the surrounding atrial myocardium. Furthermore, in group B, the SN lesions were combined with fibrosis of the atrial myocardium. The results of this investigation improve our understanding of the close relationship between the electrocardiogram findings and pathological alterations in each group. Because most human cases of SSS are due to degenerative fibrosis of the SN, the loss and disappearance of nodal cells with a corresponding increase in fatty or fibrofatty tissue, may be specific to canine cases of SSS.

Pacemaker implantation in patients with major depression, should it be of concern? A case report and literature review.

BACKGROUND: Psychological adaptation after cardiac pacemaker implantation is a challenge for patients with mental illness. CASE PRESENTATION: Here we report a self-harming patient with a psychiatric disorder. A 73-year-old female patient with 16-year coronary heart disease and a 4-year depression was admitted to our hospital for a coma. Two months earlier, the local hospital confirmed that the patient had a second-degree sinoatrial (SA) block (type 2) as well as basal septal hypertrophy with the left ventricular outflow obstruction. Therefore, metoprolol sustained-release tablets 95 mg QD and diltiazem sustained-release tablets 90 mg QD was given as treatment after a pacemaker was implanted. However, the patient had continued complaining about discomfort due to the pacemaker implanted after being discharged from the hospital. Two months later, she attempted to commit suicide by removing her pacemaker and taking 80 sleeping pills. After a series of treatments, the patient improved and was discharged without a pacemaker re-implantation. With continued anti-depression treatment and strengthen family supervision, the patient's condition is stable now. CONCLUSIONS: A suicide attempt by intentionally removing the permanent pacemaker system was rarely reported. In bradycardia patients with a history of psychological or psychiatric disease, careful evaluation should be done before and after implantation of the pacemaker.

A case report of sinoatrial arrest caused by temporal lobe epilepsy in subclinical glioblastoma.

BACKGROUND: Atrial fibrillation with symptomatic bradycardia, higher grade atrioventricular block, and sinus node disease are all common indications for permanent pacemaker implantation. The most frequent causes of sinus node disease treated with pacemaker implantation involve degenerative structural changes of the sinus node; less often, extrinsic causes (such as damage due to myocardial infarction or heightened parasympathetic nervous system activity) lead to pacemaker implantation. CASE PRESENTATION: A 50-year-old patient with syncope and documented sinoatrial arrest was referred. Neurologic exams (including CT and EEG) revealed no pathologies, so a pacemaker was implanted. Postoperatively, syncope occurred again due to a focal seizure during which sinus rhythm transitioned to atrial pacing by the device. Further neurologic testing revealed focal epilepsy. Six months later, stage IV glioblastoma was diagnosed and the patient was treated surgically. CONCLUSION: Intracerebral tumors should be considered in the differential diagnosis for patients with unexplained sinoatrial block, as well as in patients with repeat syncope after pacemaker implantation. Cranial MRI could aid the diagnostic workup of such cases.

Respuesta al ECG de octubre de 2019 / Response to ECG, October 2019

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A case of narrow complex bigeminy, what is the underlying rhythm?

Narrow complex bigeminy is a common electrocardraphic finding that can be caused by second degree sinoatrial exit block or ectopic atrial bigeminy. These rhythms can be very challenging to distinguish on a 12-lead electrocardiogram. In this case of an elderly woman who presented with narrow complex bigeminy, we review the differentiating features of second degree sinoatrial exit block and ectopic atrial bigeminy.

Sinoatrial and Atrioventricular Blocks: Who First Described Them and How? [Retrospectroscope].

The relationship among cardiac pacemakers is characterized by the fact that one pacemaker is usually dominant and all the others are subsidiary. The sinoatrial node acts as the dominant pacemaker, and all other potential pacemaker tissues are discharged by a conducted impulse before their respective diastolic depolarizations attain threshold. These pacemakers are called subsidiary to emphasize the fact that, under normal circumstances, they are engaged in conducting impulses, but, under abnormal circumstances, they may become actual pacemakers.

Respuesta al ECG de agosto de 2016 / Response to ECG, August 2016

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Registro de arritmias em pacientes com marcapassos e doença renal crônica de leve a moderada (RYCKE): resultados de um estudo de coorte observacional / Register of arrhythmias in patients with pacemakers and mild to moderate chronic kidney disease (RYCKE): results from an observational cohort study

O presente estudo examinou pacientes submetidos a implante de marcapasso dupla-câmara em decorrência de doença do nó sinusal ou bloqueio atrioventricular de 3o ou 2o graus do tipo 2 na doençarenal crônica em estágios 2, 3 e 4. O estudo teve como objetivo registrar os eventos arrítmicos durante 12 mesesde acompanhamento e comparar a incidência e a gravidade deles nas diferentes fases da doença renal crônica.Método: No total, 305 pacientes foram avaliados a cada 4 meses até 12 meses de acompanhamento. Os eventosarrítmicos foram avaliados em cada visita de acompanhamento. Resultados: Dentro do mesmo grupo de estágio da doença renal crônica não houve diferença entre as causas doença do nó sinusal e bloqueio atrioventricular, a respeito da ocorrência de qualquer arritmia. No entanto, menor incidência de taquicardia atrial/fibrilação atrial foi observada para todas as comparações entre todos os pacientes e os mesmos subgrupos em pacientes no estágio 2 (total: 58%; doença do nó sinusal: 63%; bloqueio atrioventricular: 51%), comparativamente aos estágios 3 (total:87%, P < 0,0001; doença do nó sinusal: 89%, P = 0,0020; bloqueio atrioventricular: 84%, P = 0,0019) e 4 (total: 85%, P < 0,0001; doença do nó sinusal: 81%, P = 0,0409; bloqueio atrioventricular: 90%, P < 0,0001). Em relação à taquicardia ventricular não sustentada/taquicardia ventricular sustentada, foi observada incidência mais elevada para todas as comparações entre todos os pacientes e os mesmos subgrupos em pacientes no estágio 4 (total: 32%; doença do nó sinusal: 16%; bloqueio atrioventricular: 16%), comparativamente aos estágios 3 (total: 11%, P = 0,0007; doença do nó sinusal: 9%, P = 0,0110; bloqueio atrioventricular: 14%, P = 0,0441) e 2 (total: 3%, P < 0,0001; doença do nó sinusal: 3%, P < 0,0001; bloqueio atrioventricular: 4%, P < 0,0001). Conclusão: Nossos resultados sugerem que quanto mais avançado o estágio da doença renal crônica maior a incidência de arritmias malignas...

The present study evaluated patients who had received a dual chamber pacemaker implant due to sinus node disease or 3rd/2nd degree type 2 atrioventricular block in chronic kidney disease stages 2, 3 and 4. The study was aimed at registering arrhythmic events for 12 months of follow-up and comparing their incidence and severity in different stages of chronic kidney disease. Method: Three hundred and five patients were evaluated every 4 months up to 12 months of follow-up. Arrhythmic events were assessed at each follow-up visit. Results: Within the same chronic kidney disease stage group there was no difference between the causes ofsinus node disease and atrioventricular block for the occurrence of any arrhythmia. However, a lower incidence of atrial fibrillation/tachycardia was observed for all comparisons among all patients and the same subgroups in stage 2 patients (total: 58%; sinus node disease: 63%; atrioventricular block: 51%) compared to stages 3 (total: 87%,P < 0.0001; sinus node disease: 89%, P = 0.0020; atrioventricular block: 84%, P = 0.0019) and 4 (total: 85%,P < 0.0001; sinus node disease: 81%, P = 0.0409; atrioventricular block: 90%, P < 0.0001). Regarding nonsustained/ sustained ventricular tachycardia, a higher incidence was observed for all comparisons among all patients and the same subgroups in stage 4 patients (total: 32%; sinus node disease: 16%; atrioventricular block: 16%) compared to stages 3 (total: 11%, P = 0.0007; sinus node disease: 9%, P = 0.0110; atrioventricular block: 14%, P = 0.0441) and 2 (total: 3%, P < 0.0001; sinus node disease: 3%, P < 0.0001; atrioventricular block: 4%,P < 0.0001). Conclusion: Our findings suggest that the more advanced the stage of chronic kidney disease, thegreater the incidence of malignant arrhythmias...

P-wave pseudonormalization after iatrogenic coronary sinus isolation.

We report a case of a 58 year old gentleman with prior history of catheter ablation for persistent atrial fibrillation (AF). His baseline ECG showed sinus rhythm with a broad and notched P-wave in lead II and biphasic P-wave (positive/negative) in leads III and aVF previously described as advanced interatrial block. A redo ablation procedure was performed due to AF recurrence. An iatrogenic isolation of the coronary sinus (CS) was observed during ablation with marked narrowing and loss of the terminal negative component of the P-wave on the surface ECG.

Large doses of uterotonic drugs caused type II second degree sinoatrial block during cesarean section.

In China, it is a routine procedure to inject 250 µg of hemabate (sterile solution, an oxytocic, contains the tromethamine salt of the (I5S)-15 methyl analogue of naturally occurring prostaglandin F2α in a solution suitable for intramuscular injection) into the myometrium of patients experiencing uterine inertia after delivery, with an additional dose given in the event that the efficacy is not obvious. Although hemabate is prohibited from being used in patients with active liver disease, there are no restrictions regarding the application of hemabate in positive hepatitis B surface antigen (HbsAg)-positive subjects with normal liver function. Here we report adverse effects of hemabate in 1 HbsAg-positive subject with normal liver function. This subject experienced increased blood pressure, chest tightness, and type II second degree sinoatrial block 25 minutes after an additional injection of hemabate. Thus, special attention should be paid when applying hemabate in HbsAgpositive subjects with normal liver function.

Long-term effects of frequent maximal breath-holding on the cardiac health of elite freedivers.

Cardiac arrhythmias are commonly reported in freedivers during maximal voluntary breath-holds, but their influence on the cardiological status and their long-term effects on the cardiac health of these athletes have not been investigated. Here we present the results of a study on 32 healthy young men (mean age 32.6 ± 1.3 years) who were divided into two groups of 16 subjects. One group included 16 continuously training freedivers at the "high achievers in sports" level (DIVERS group). The CONTROL group included 16 healthy young men not involved in sports. The subjects were monitored using 24-h electrocardiogram (ECG), and echocardiological study (EchoCG) for all the subjects was performed. The mean heart rate in the DIVERS group was 69.5 ± 1.7 bpm compared with 70.9 ± 1.5 bpm in the CONTROL group. The minimal heart rate was 42.3 ± 1.0 bpm in the DIVERS group and 48.8 ± 1.7 bpm in the CONTROL group (P < 0.005). The maximal heart rate was 132.8 ± 4.6 bpm in the DIVERS group and 132.1 ± 2.9 bpm in the CONTROL group. ECG analysis revealed supraventricular arrhythmias in the DIVERS group: four of the DIVERS (25%) exhibited supraventricular couplets and triplets, three (19%) exhibited transient first- and second-degree AV blocks (Mobitz type 1) at night, and one (6%) exhibited a second-degree sinoatrial block at night. According to the echocardiogram, the DIVERS had slightly larger left ventricles (5.1 ± 1.33, P < 0.05) and left atriums (41.1 ± 12.7) compared with the CONTROL group without exceeding the normal values. The right ventricle volume (3.6 ± 0.69, P < 0.05) was somewhat above the upper normal value (up to 3.5 cm). In conclusion, freediving athletes exhibited changes in their cardiac status, most likely due to the regular exercise, that were not associated with regular maximal voluntary breath-holds. These changes are within the normal physiological values and do not limit their freediving practice.

A protective role of Nox1/NADPH oxidase in a mouse model with hypoxia-induced bradycardia.

Although it has been reported that endotoxin-induced expression of Nox1 in the heart contributes to apoptosis in cardiomyocytes, functional role of Nox1 at the physiological expression level has not been elucidated. The aim of this study was to clarify the role of Nox1 under a hypoxic condition using wild-type (WT, Nox1(+/Y)) and Nox1-deficient (Nox1(-/Y)) mice. ECG recordings from anesthetized mice revealed that Nox1(-/Y) mice were more sensitive to hypoxia, resulting in bradycardia, compared to WT mice. Atrial and ventricular electrocardiograms recorded from Langendorff-perfused hearts revealed that hypoxic perfusion more rapidly decreased heart rate in Nox1(-/Y) hearts compared with WT hearts. Sinus node recovery times measured under a hypoxic condition were prolonged more markedly in the Nox1(-/Y) hearts. Sinoatrial node dysfunction of Nox1(-/Y) hearts during hypoxia was ameriolated by the pre-treatment with the Ca(2+) channel blocker nifedipine or the K(+) channel opener pinacidil. Spontaneous action potentials were recorded from enzymatically-isolated sinoatrial node (SAN) cells under a hypoxic condition. There was no significant difference in the elapsed times from the commencement of hypoxia to asystole between WT and Nox1(-/Y) SAN cells. These findings suggest that Nox1 may have a protective effect against hypoxia-induced SAN dysfunction.

Clinical significance of second degree Wenckebach type sinoatrial block identified during Holter monitoring in patients with symptoms suggestive of arrhythmia.

AIMS: To determine the clinical significance of the sinoatrial block II° of the Wenckebach type (block W) identified during Holter monitoring. METHODS AND RESULTS: The study included 300 patients (mean age 54 ± 17 years; 130 women) with symptoms suggestive of arrhythmia who underwent Holter monitoring. Block W was identified by a dedicated computer program and subsequently confirmed by a cardiologist. Block W was diagnosed in 88 patients (29%). It occurred only during sleep in 37 (12%) patients and during both daytime activity and sleep in 51 (17%) patients. Block W only during sleep happened predominately in young patients aged between 20 and 30 years, whereas episodes that occurred during both daytime and sleep were found mainly in patients between 60 and 70 years of age. Prospective observation time averaged 41 ± 11 months, and the time to the diagnosis of sinus node disease was 26 ± 10 months. Cox multivariate analyses showed that block W during both daytime and sleep is an independent predictor for the future diagnosis of sinus node disease [hazard ratio-13.6 (5.2-35.5); P < 0.0001]. Age-specific analyses confined this effect to the patients ≥50 years of age. The results also suggest that in patients ≥50 years of age block W during both daytime and sleep may be related to a significant improvement in survival [hazard ratio-0.03 (0.007-0.16); P < 0.0001]. CONCLUSION: Block W during daytime activity in patients with symptoms suggestive of arrhythmia indicates an increased likelihood of the future diagnosis of sinus node disease.

Diurnal modulation and sources of variation affecting ventricular repolarization in Warmblood horses.

OBJECTIVES: Irregularities in cardiac repolarization are known to predispose for arrhythmias and sudden cardiac death in humans. The QT interval is a quantitative measurement of repolarization, and clinically, the QTc (QT interval corrected for heart rate) and Tpeak to Tend intervals (TpTe) are used as repolarization markers. To support the use of these markers in horses, we sought to describe the possible influence of the environment, time of day, day-to-day effects, T wave conformation, age, body weight (BW), and horse-to-horse variation on repolarization measurements. ANIMALS: 12 Warmblood geldings, age 10.8 ± 4.8 years. METHODS: Holter ECGs were performed on days 0, 7 and 14. Measures of RR, QT, QTp, QTc and TpTe intervals and T wave conformation were obtained each hour during the recordings. An ANCOVA analysis was performed to estimate diurnal variation and the sources of variation affecting these intervals. RESULTS: Differences between individual horses were the largest source of repolarization variability although the environment had a significant effect on repolarization as well. Diurnal variation affected both the RR interval and the repolarization markers. The QT, QTc and TpTe intervals were prolonged on day 0. Biphasic T waves shortened the TpTe interval approximately 10 ms. Age and BW did not appear to affect repolarization. CONCLUSIONS: Equine repolarization markers exhibit significant variation. Factors affecting repolarization measurements include horse-to-horse variation, diurnal variation, the environment, and T wave conformation. These factors must be considered if markers of equine repolarization are used diagnostically.

A Case of Sick Sinus Syndrome in a Patient with Systemic Sclerosis / 대한내과학회지

Systemic sclerosis (SSc) is characterized by the presence of microvascular disease and various patterns of cutaneous and parenchymal fibrosis. Manifestation of SSc may occur in numerous tissues and organs and can be particularly problematic when present in the lungs, kidneys or heart. Cardiac involvement in SSc includes pericarditis, myocardial disease, conduction abnormalities, and arrhythmia. Sick sinus syndrome is described as a combination of symptoms (dizziness, confusion, fatigue, syncope and congestive heart failure) caused by sinus node dysfunction and manifested by marked sinus bradycardia, sinoatrial block, or sinus arrest. Sinus node dysfunction is most often seen in the elderly but also, rarely, in systemic amyloidosis and connective tissue disease. Sick sinus syndrome is rarely found in patients with SSc, of which there has been only one case report, according to a review of the literature. Therefore, we report a case of sick sinus syndrome in a 71-year-old female with SSc.