Exercise induced bradycardia

Deep freediving exposes humans to hypoxia and dramatic changes in pressure. The effect of depth on gas exchange may enhance risk of hypoxic blackout (BO) during the last part of the ascent. Our aim was to investigate arterial oxygen saturation (SpO2 ) and heart rate (HR) in shallow and deep freedives, central variables, which have rarely been studied underwater in deep freediving. Four male elite competitive freedivers volunteered to wear a newly developed underwater pulse oximeter for continuous monitoring of SpO2 and HR during self-initiated training in the sea...

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a severe genetic arrhythmogenic disorder characterized by adrenergically induced ventricular tachycardia manifesting as stress-induced syncope and sudden cardiac death. While CPVT is not associated with dilated cardiomyopathy (DCM) in most cases, the combination of both disease entities poses a major diagnostic and therapeutic challenge. CASE SUMMARY: We present the case of a young woman with CPVT...

INTRODUCTION: Cannabis use is known to be associated with significant cardiovascular morbidity. We describe three cases of cannabis-related malignant arrhythmias, who presented to the cardiac department at our institution within the last 2 years. All three patients were known to smoke cannabis on daily basis. CASE SUMMARIES: Case 1: A 30-year-old male, presented with recent onset of palpitations. A 12-lead electrocardiogram (ECG), transthoracic echocardiogram (TTE), and blood tests were all normal...

A 62-year-old woman with activity-dependent two-to-one atrioventricular block (2:1AVB) and a normal left ventricular ejection fraction was referred to our department for the evaluation of exclusively exercise-induced marked symptoms. The treadmill test helped establish a clear correlation between 2:1AVB and symptoms. The test results demonstrated that exercise-induced marked symptoms were attributed to abrupt transient hypotension combined with relative bradycardia, probably due to increased diastolic mitral and tricuspid regurgitation because of 2:1AVB during moderate-to-heavy exercise...

PURPOSE: The purpose of this systematic review was to evaluate fetal and maternal pregnancy outcomes of elite athletes who had participated in competitive sport immediately before conception. METHODS: Online databases were searched up to March 24, 2020. Studies of any design and language were eligible if they contained information on the relevant population (pregnant women), exposure (engaged in elite sport immediately before pregnancy), and outcomes (birth weight, low birth weight, macrosomia, preterm birth, fetal heart rate and pulse index, cesarean sections, instrumental deliveries, episiotomies, duration of labor, perineal tears, pregnancy-induced low back pain, pelvic girdle pain, urinary incontinence, miscarriages, prenatal weight gain, inadequate/excess prenatal weight gain, maternal depression or anxiety)...

The potential benefit of heart rate reduction (HRR), independent of β-blockade, on right ventricular (RV) function in pulmonary hypertension (PH) remains undecided. We studied HRR effects on RV fibrosis and function in PH and RV pressure-loading models. Adult rats were randomized to 1 ) sham controls, 2 ) monocrotaline (MCT)-induced PH, 3 ) SU5416 + hypoxia (SUHX)-induced PH, or 4 ) pulmonary artery banding (PAB). Ivabradine (IVA) (10 mg/kg/d) was administered from 2 weeks after PH induction or PAB. Exercise tolerance, echocardiography, and pressure-volume hemodynamics were obtained at a terminal experiment 3 weeks later...

Acute inferior myocardial damage can induce transient bradycardia and hypotension-the Bezold-Jarisch reflex, which is explained by the preferential distribution of vagal nerves in the inferior wall of the left ventricle. We report a 76-year-old man who showed a perfusion defect in the inferior wall with redistribution on exercise scintigraphy with thallium-201. Of note, during exercise at an intensity of 100 watts, the patient's heart rate transiently decreased from 122 to 95 bpm in sinus rhythm, accompanied by ST-segment depression...

AIM: To evaluate physical fitness and cardiovascular effects in rats with renovascular hypertension, two kidneys, one clip (2K1C) submitted to voluntary exercise (ExV). MAIN METHODS: 24 h after surgery (SHAM and 2K1C) rats were submitted to ExV for one week (adaptation). ExV adherent rats were separated into exercise (2K1C-EX and SHAM-EX) or sedentary (2K1C-SED and SHAM-SED) groups. After 4 weeks, exhaustion test, plasma lactate, cardiovascular parameters were evaluated and gastrocnemius muscle was removed for evaluation of gene expression of muscle metabolism markers (PGC1α; AMPK, SIRT-1, UCP-3; MCP-1; LDH) and of the redox process...

BACKGROUND: High-intensity intermittent training (HIIT) is an emerging strategy for controlling blood pressure (BP) requiring intermittent exercise. However, few studies were focused on clinical test or related mechanisms. Here we compared the detailed aspects of HIIT on rat blood pressure control and explored its possible molecular mechanisms. METHODS: Thirty-six spontaneous hypertensive rats (SHR) were recruited to complete 8 weeks of different training pattern using treadmill...

Exercise is, together with diet, a powerful health-promoting habit. However, an association of intense physical activity with the onset of atrial and ventricular arrhythmias, and sudden death has been described. Although initially questioned, the atrial pro-arrhythmic role of endurance physical activity is now well accepted in the scientific community. Atrial fibrillation is common among endurance athletes, being a source of morbidity in otherwise healthy young and middle-aged individuals. The mechanisms for its development are still poorly understood, but likely involve some components of the athlete's heart (e...

GABAergic inhibitory input within the paraventricular hypothalamic nucleus (PVN) plays a key role in restraining sympathetic outflow. Although experimental evidence has shown depressed GABAA receptor function plus sympathoexcitation in hypertension and augmented GABA levels with reduced sympathetic activity after exercise training (T), the mechanisms underlying T-induced effects remain unclear. Here we investigated in T and sedentary (S) SHR and WKY: (1) time-course changes of hemodynamic parameters and PVN glutamic acid decarboxylase (GAD) isoforms' expression; (2) arterial pressure (AP) and heart rate (HR) responses, sympathetic/parasympathetic modulation of heart and vessels and baroreflex sensitivity to GABAA receptor blockade within the PVN...

BACKGROUND: Lyme disease (LD), is the most common vector-borne illness in the US and Europe, with predominantly cutaneous, articular, cardiac and neuro-psychiatric manifestations. LD affects all layers of the heart and every part of the conducting system. Carditis is a less common manifestation of LD. Heart block (HB) as the initial and sole manifestation of LD is rare. Inducible HB has never been reported in LD. We report a case of heart block (HB) inducible with exercise and reversible with rest...

Sudden cardiac death in athletes is rare and most often unexpectable. For a better understanding of cardiac remodeling, this study presents the effects of chronic vigorous exercise on cardiac structure and electrophysiology in new rabbit and dog athlete's heart models. Rabbits and dogs were randomized into sedentary ('Sed'), exercised (subjected to 16 weeks chronic treadmill exercise ('Ex') groups, and a testosterone-treated ('Dop') group in dogs. Echocardiography and electrocardiogram were performed. Proarrhythmic sensitivity and autonomic responses were tested in conscious dogs...

BACKGROUND: RYR2, encoding cardiac ryanodine receptor, is the major responsible gene for catecholaminergic polymorphic ventricular tachycardia (CPVT). Meanwhile, KCNJ2, encoding inward-rectifier potassium channel (IK1 ), can be the responsible gene for atypical CPVT. We recently encountered a family with CPVT and sought to identify a responsible gene variant. METHODS: A targeted panel sequencing (TPS) was employed in the proband. Copy number variation (CNV) in RYR2 was identified by focusing on read numbers in the TPS and long-range PCR...

While the implantable pacemaker has initially been developed to treat symptomatic bradycardia, we demand of modern devices that they also function properly during exercise. In recent years, device manufacturers have implemented multiple proprietary algorithms which aim to improve pacemaker function by avoiding unnecessary right ventricular pacing, optimizing atrial refractory periods and diagnosing pacemaker mediated tachycardia. When activated, these algorithms may save the associated EGM into the device memory which enables later analysis by remote monitoring or device interrogation...

KEY POINTS: The sinoatrial node (SAN) is the primary pacemaker of the heart. SAN dysfunction, or 'sick sinus syndrome', can cause excessively slow heart rates and pauses, leading to exercise limitation and syncope, currently treated by implantation of an electronic pacemaker. 'Biopacemaking' utilises gene therapy to restore pacemaker activity by manipulating gene expression. Overexpressing the HCN pacemaker ion channel has been widely used with limited success. We utilised bradycardic rat subsidiary atrial pacemaker tissue to evaluate alternative gene targets: the Na+ /Ca2+ exchanger NCX1, and the transcription factors TBX3 and TBX18 known to be involved in SAN embryonic development...

Studies showed that physical exercise decreases the risk of developing Parkinson's disease (PD) as slowing its progression. Nitric oxide (NO) increases in the substantia nigra pars compacta (SNpc) of individuals with PD. However, no study has evaluated the effects of exercise on peripheral NO levels and its modulatory effects on cardiovascular dysfunctions of subjects with PD. Trained (T) or sedentary (S) animals underwent stereotactic surgery for bilateral 6-hydroxydopamine (6-OHDA) or vehicle microinfusion (Sham group)...

Objective Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal inherited disease characterized by ventricular arrhythmias induced by physical exercise or emotional stress. The major cause of CPVT is mutations in RYR2, which encodes the cardiac ryanodine receptor channel. Recent advances in sequencing technology have yielded incidental findings of RYR2 variants in other cardiac diseases. Analyzing the characteristics of RYR2 variants related to CPVT will be useful for differentiation from those related to other cardiac diseases...

Exercise is an emerging cause of atrial fibrillation (AF) in young individuals without coexisting cardiovascular risk factors. The causes of exercise-induced atrial fibrillation remain largely unknown, and conclusions are jeopardised by apparently conflicting data. Some components of the athlete's heart are known to be arrhythmogenic in other settings. Bradycardia, atrial dilatation and, possibly, atrial premature beats are therefore biologically plausible contributors to exercise-induced AF. Challenging findings in an animal model suggest that exercise might also prompt the development of atrial fibrosis, possibly due to cumulative minor structural damage after each exercise bout...

BACKGROUND: High-level physical training induces cardiac structural and functional changes, including 12-lead electrocardiogram modifications. OBJECTIVES: The purpose of this cross-sectional longitudinal study was to establish a quantitative electrocardiographic profile in highly trained football players. Initial and serial annual electrocardiogram monitoring over subsequent years allowed us to investigate the long-term effects of exercise on cardiac conduction and electrophysiological remodelling...