A Patient With Athlete's Heart Syndrome: When the Abnormal Is Normal.

Long-term athletic training can result in structural and conduction changes within the heart, leading to Athlete's heart syndrome (AHS). This syndrome is characterized by increased left ventricle (LV) dimensions, thickness, and mass. Dynamic exercise significantly contributes to these alterations, with sinus bradycardia being a common conduction abnormality, often accompanied by first-degree atrioventricular (AV) block. However, higher degrees of AV conduction abnormalities, such as second- and third-degree blocks, though rare, might occur due to parasympathetic hypertonia. Prompt evaluation is necessary to rule out underlying structural or infiltrative heart diseases. We present the case of a 66-year-old lifelong long-distance runner with marked sinus bradycardia, AV dissociation, and junctional escape rhythm, alongside left ventricular hypertrophy (LVH) and T-wave repolarization abnormalities. Subsequent studies ruled out possible pathologies, and the patient was diagnosed with AHS, characterized by cardiac remodeling and bradycardia due to prolonged cardiac loading. This case underscores the importance of clinical assessment, cardiac imaging, and exclusion of pathologic causes to distinguish normal physiological adaptations from potentially concerning conditions.

Black Cohosh: An Uncommon Culprit of Bradycardia in Postmenopausal Women.

The use of herbal supplements has become increasingly prevalent, with black cohosh (BC) gaining popularity for managing menopausal symptoms. However, reports of adverse effects associated with BC are limited. We present a case of bradycardia linked to prolonged BC ingestion. A 76-year-old postmenopausal woman who has been taking BC for years has had syncopal attacks multiple times during the past years associated with bradycardia with the heart rate dropping to 30 beats/minute with no identifiable cause. Discontinuation of BC resulted in a gradual resolution of bradycardia, highlighting a plausible association. There were no additional pharmacological or invasive interventions required.

An Unusual Presentation of Adult Intussusception.

Intussusception is a condition characterized by the invagination of a proximal segment of the intestine into a distal segment. In adults, intussusception is commonly associated with a lead point. The most alarming lead point is an obstructing malignancy. Here, we present the case of a 57-year-old woman with ileocolic intussusception secondary to colonic adenocarcinoma. The patient presented to the emergency department following an incidental finding of bradycardia, with a heart rate of around 40 beats per minute. She presented with several weeks of cramping, right lower quadrant abdominal pain, lightheadedness, fatigue, and palpitations. A computed tomography scan revealed ileocolic intussusception. After the placement of a semi-permanent right subclavian pacer, the patient underwent a right hemicolectomy. Surgical findings were consistent with ileocolic intussusception suspicious of being initiated by a mass in the right cecum involving the appendiceal orifice and ileocecal valve that invaded through the muscularis propria into subserosal tissue. The mass was resected and sent to pathology, where it was classified as stage II colonic adenocarcinoma. This case highlights a nonspecific presentation of intussusception that was only identified due to incidental bradycardia.

Arrhythmia and Time of Day in Maintenance Hemodialysis: Secondary Analysis of the Monitoring in Dialysis Study.

Rationale & Objective: The incidence of arrhythmia varies by time of day. How this affects individuals on maintenance dialysis is uncertain. Our objective was to quantify the relationship of arrhythmia with the time of day and timing of dialysis. Study Design: Secondary analysis of the Monitoring in Dialysis study, a multicenter prospective cohort study. Settings & Participants: Loop recorders were implanted for continuous cardiac monitoring in 66 participants on maintenance dialysis with a follow up of 6 months. Exposure: Time of day based on 6-hour intervals. Outcomes: Event rates of clinically significant arrhythmia. Analytical Approach: Negative binomial mixed effects regression models for repeated measures were used to evaluate data from the Monitoring in Dialysis study for differences in diurnal patterns of clinically significant arrhythmia among those with end-stage kidney disease with heart failure and end-stage kidney disease alone. We additionally analyzed rates according to presence of heart failure, time of dialysis shift, and dialysis versus nondialysis day. Results: Rates of clinically significant arrhythmia peaked between 12:00 AM and 5:59 AM and were more than 1.5-fold as frequent during this interval than the rest of the day. In contrast, variations in atrial fibrillation peaked between 6:00 AM and 11:59 AM, but variations across the day were qualitatively small. Clinically significant arrhythmia occurred at numerically higher rate in individuals with end-stage kidney disease and heart failure (5.9 events/mo; 95% CI, 1.3-26.8) than those without heart failure (4.0 events/mo; 95% CI, 0.9-17.9). Although differences in overall rate were not significant, their periodicity was significantly different (P < 0.001), with a peak between 12:00 AM and 6:00 AM with kidney failure alone and between 6:00 AM and 11:59 AM in those with heart failure. Although the overall clinically significant arrhythmia rate was similar in morning compared with evening dialysis shifts (P = 0.43), their periodicity differed with a peak between 12:00 AM and 5:59 AM in those with AM dialysis and a later peak between 6:00 AM and 11:59 AM in those with PM shifts. Limitations: Post hoc analysis, unable to account for unmeasured confounders. Conclusion: Clinically significant arrhythmias showed strong diurnal patterns with a maximal peak between 12:00 AM and 5:59 AM and noon. Although overall arrhythmia rates were similar, the peak rate occurred overnight in individuals without heart failure and during the morning in individuals with heart failure. Further exploration of the influence of circadian rhythm on arrhythmia in the setting of hemodialysis is needed.

Arrhythmias occur with a high frequency in individuals with kidney failure. We sought to understand whether there were diurnal patterns for common types of arrhythmias in individuals with kidney failure. We used continuous rhythm data from 66 individuals on dialysis with implantable loop recorders. We found that clinically significant arrhythmias including bradycardia primarily occur overnight and in the early morning, whereas atrial fibrillation is more evenly distributed during the day.

Intrauterine Transfusion for Rhesus Alloimmunization: A Historical Retrospective Cohort from A Single Reference Center in Brazil.

Objective: This study aimed to describe the historical experience of a single reference center in Brazil with intrauterine transfusion (IUT) for Rhesus (Rh) alloimmunization, evaluating the major complications and the perinatal outcomes of this procedure. Methods: This retrospective cohort study evaluated data from medical records of pregnant women between 20 and 34 weeks of gestation whose fetuses underwent IUT by cordocentesis between January 1991 and June 2021. The same experienced examiner performed all procedures. Univariate and multivariate logistic regression was used to assess the effect of fetal hydrops, duration of IUT, post-transfusion cord bleeding time, and bradycardia on death (fetal or neonatal). Results: We analyzed data from 388 IUTs in 169 fetuses of alloimmunized pregnant women with a mean age of 29.3 ± 5.1 years. Death and fetal hydrops were significantly associated at first IUT (p < 0.001). We had two cases of emergency cesarean section (mean of 0.51% per IUT) and three cases of premature rupture of the ovular membranes (mean of 0.77% per procedure). Thirty-six deaths were recorded, including 14 intrauterine and 22 neonatal. A higher percentage of neonatal deaths was observed in the group with post-transfusion cord bleeding time > 120 s (45.8%). The odds of neonatal death were 17.6 and 12.9 times higher in cases with hydrops and bradycardia than in cases without hydrops and bradycardia, respectively. The odds of death (fetal and neonatal) were 79.9 and 92.3 times higher in cases with hydrops and bradycardia than in cases without hydrops and bradycardia, respectively. Conclusions: The most common complications of IUT for Rh alloimmunization were post-transfusion cord bleeding, fetal bradycardia, premature rupture of ovular membranes, and emergency cesarean section. The IUT complication most associated with death (fetal and neonatal) was bradycardia, and the perinatal outcomes were worse in fetuses with hydrops.

Bradycardia, Renal Dysfunction, Atrioventricular Nodal Blockade, Shock, and Hyperkalemia (BRASH) Syndrome: A Case Report Highlighting the Importance of Early Recognition and Management.

BRASH syndrome, characterized by bradycardia, renal dysfunction, atrioventricular nodal blockade, shock, and hyperkalemia, is a newly defined condition that can lead to significant morbidity and mortality if not promptly recognized and treated. The triggers for this syndrome often include medication interactions, dehydration, and nephrotoxic insults, particularly in older patients with limited renal reserve and cardiovascular disease. In this report, we present the case of an 88-year-old female with multiple comorbidities who exhibited symptoms of prostration, bradycardia, hypotension, and altered mental status, along with laboratory findings (hyperkalemia and renal dysfunction) consistent with BRASH syndrome, triggered by hypovolemia associated with a urinary tract infection. Immediate treatment must focus on correcting hyperkalemia, providing hemodynamic support for bradycardia and hypotension, and administering guided fluid resuscitation. Prompt identification and management of the syndrome can prevent the need for invasive interventions, such as pacemaker insertion and dialysis. Healthcare professionals should be vigilant in considering BRASH syndrome, especially in older patients with cardiac disease, limited renal function, and those on medication regimens that include AV-nodal blocking agents, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and potassium-sparing diuretics. This case report emphasizes the importance of clinical suspicion and the initiation of timely treatment to interrupt the cycle of BRASH syndrome and improve patient outcomes.

Reference ranges for ambulatory heart rate measurements in a middle-aged population.

BACKGROUND: Elevated heart rate (HR) predicts cardiovascular disease and mortality, but there are no established normal limits for ambulatory HR. We used data from the Swedish CArdioPulmonary Imaging Study to determine reference ranges for ambulatory HR in a middle-aged population. We also studied clinical correlates of ambulatory HR. METHODS: A 24-hour ECG was registered in 5809 atrial fibrillation-free individuals, aged 50-65 years. A healthy subset (n=3942) was used to establish reference values (excluding persons with beta-blockers, cardiovascular disease, hypertension, heart failure, anaemia, diabetes, sleep apnoea or chronic obstructive pulmonary disease).Minimum HR was defined as the lowest 1-minute HR. Reference ranges are reported as means±SDs and 2.5th-97.5th percentiles. Clinical correlates of ambulatory HR were analysed with multivariable linear regression. RESULTS: The average mean and minimum HRs were 73±9 and 48±7 beats per minute (bpm) in men and 76±8 and 51±7 bpm in women; the reference range for mean ambulatory HR was 57-90 bpm in men and 61-92 bpm in women. Average daytime and night-time HRs are also reported. Clinical correlates, including age, sex, height, body mass index, physical activity, smoking, alcohol intake, diabetes, hypertension, haemoglobin level, use of beta-blockers, estimated glomerular filtration rate, per cent of predicted forced expiratory volume in 1 s and coronary artery calcium score, explained <15% of the interindividual differences in HR. CONCLUSION: Ambulatory HR varies widely in healthy middle-aged individuals, a finding with relevance for the management of patients with a perception of tachycardia. Differences in ambulatory HR between individuals are largely independent of common clinical correlates.

Apnea, Intermittent Hypoxemia, and Bradycardia Events Predict Late-Onset Sepsis in Extremely Preterm Infants.

OBJECTIVE: To examine the association of cardiorespiratory events, including apnea, periodic breathing, intermittent hypoxemia (IH), and bradycardia, with late-onset sepsis for extremely preterm infants (<29 weeks' gestational age [GA]) on versus off invasive mechanical ventilation. STUDY DESIGN: This is a retrospective analysis of data from infants enrolled in Pre-Vent (ClinicalTrials.gov identifier NCT03174301), an observational study in five level IV neonatal intensive care units. Clinical data were analyzed for 737 infants (mean GA 26.4 weeks, SD 1.71). Monitoring data were available and analyzed for 719 infants (47,512 patient-days), of whom 109 had 123 sepsis events. Using continuous monitoring data, we quantified apnea, periodic breathing, bradycardia, and IH. We analyzed the relationships between these daily measures and late-onset sepsis (positive blood culture >72 hours after birth and ≥5d antibiotics). RESULTS: For infants not on a ventilator, apnea, periodic breathing, and bradycardia increased before sepsis diagnosis. During times on a ventilator, increased sepsis risk was associated with longer events with oxygen saturation <80% (IH80) and more bradycardia events before sepsis. IH events were associated with higher sepsis risk, but did not dynamically increase before sepsis, regardless of ventilator status. A multivariable model including post menstrual age, cardiorespiratory variables (apnea, periodic breathing, IH80, and bradycardia), and ventilator status predicted sepsis with an AUC of 0.783. CONCLUSION: We identified cardiorespiratory signatures of late-onset sepsis. Longer IH events were associated with increased sepsis risk but did not change temporally near diagnosis. Increases in bradycardia, apnea, and periodic breathing preceded the clinical diagnosis of sepsis.

Severe bradycardia at acute medical take - Think about myxoedema coma.

We report two cases of myxoedema coma that presented to the acute medical take with severe bradycardia. These patients were initially misdiagnosed as bradyarrhythmia of primary cardiac origin. They were then diverted to the cardiology service at another district general hospital (DGH) for admissions. Both cases were subsequently diagnosed with myxoedema coma having screened thyroid function tests on arrival at the cardiology unit. Despite being treated for myxoedema coma, both patients unfortunately succumbed to the disease and later died in the hospital. These cases highlight that clinical suspicion and recognition of myxoedema coma remain significant challenges in a developed world despite readily available and highly sensitive thyroid hormone assays.

Bradycardia, Renal Failure, Atrioventricular Block, Shock, and Hyperkalemia (BRASH) Syndrome Emergence in a Unique Intersection of COVID-19 and End-Stage Renal Disease: A Case Report.

Bradycardia, renal failure, atrioventricular (AV) block, shock, and hyperkalemia (BRASH) syndrome is a rare clinical entity that poses challenges for healthcare practitioners. It is characterized by bradycardia, renal failure, atrioventricular (AV) obstruction, shock, and hyperkalemia. This case is an interesting instance of BRASH syndrome in the setting of COVID-19 infection and end-stage renal disease (ESRD). Initial laboratory results revealed macrocytic anemia, renal dysfunction, acidosis, and mild hyponatremia, along with hyperkalemia. An electrocardiogram (EKG) and telemonitoring showed dopamine-resistant persistent bradycardia until transvenous temporary pacemaker placement was done, which resolved the bradycardia. Anti-hyperkalemic therapy, avoiding AV nodal-blocking medication, and temporary pacemaker placement were all part of the management. After receiving hemodialysis, the patient gradually recovered. Bradycardia improved and potassium normalized. The intricate interaction between hyperkalemia and AV nodal obstruction that causes BRASH syndrome results in severe bradycardia and shock. To the best of our knowledge, this is the first case of BRASH syndrome in a patient with an active COVID-19 infection in a previously vaccinated patient. Even though case reports make up the majority of the material currently in publication, to fully comprehend the mechanisms underlying this illness, more research is required, as early detection of this syndrome is crucial for better patient outcomes.

Cardiac remodeling in patients with atrial fibrillation reversing bradycardia-induced cardiomyopathy: A case report.

BACKGROUND: Bradycardia-induced cardiomyopathy (BIC), which is a disease resulting from bradycardia, is characterized by cardiac chamber enlargement and diminished cardiac function. The correction of bradycardia can allow for significant improvements in both cardiac function and structure; however, this disease has been infrequently documented. In this case, we conducted a longitudinal follow-up of a patient who had been enduring BIC for more than 40 years to heighten awareness and prompt timely diagnosis and rational intervention. CASE SUMMARY: A woman who presented with postactivity fatigue and dyspnea was diagnosed with bradycardia at the age of 7. Since she had no obvious symptoms, she did not receive any treatment to improve her bradycardia during the 42-year follow-up, except for the implantation of a temporary pacemaker during labor induction surgery. As time progressed, the patient's heart gradually expanded due to her low ventricular rate, and she was diagnosed with BIC. In 2014, the patient developed atrial fibrillation, her ventricular rate gradually increased, and her heart shape gradually returned to normal. This report describes the cardiac morphological changes caused by the heart rate changes in BIC patients older than 40 years, introduces another possible outcome of BIC, and emphasizes the importance of early intervention in treating BIC. CONCLUSION: BIC can induce atrial fibrillation, causing an increased ventricular rate and leading to positive cardiac remodeling.

Beyond the Meninges: A Unique Cardiac Complication of Streptococcus pneumoniae Meningitis.

We present a case of a 30-year-old male who was admitted with Streptococcus pneumoniae meningitis. He initially responded well to antibiotic therapy. However, the patient later developed symptomatic sinus bradycardia, which was likely due to intracranial hypertension. Even though the patient showed overt symptoms, vigilant monitoring, interdisciplinary collaboration, and cardiac evaluation helped avoid unnecessary interventions. This case highlights the importance of recognizing and managing rare cardiac complications associated with central nervous system infections.

Adverse Drug Events Observed with the Newly Approved Remimazolam in Comparison to Propofol for General Anesthesia in Patients Undergoing Surgery: A Meta-analysis.

INTRODUCTION: Developments in anesthetic pharmacology have been aiming at minimizing physiological disturbance in addition to maintaining and improving titrateability, recovery profile, and patient experience. Remimazolam, a GABAAlpha receptor agonist, is a new intravenous anesthetic agent which has recently been approved for use. This analysis aimed to systematically compare the adverse drug events reported with the newly approved remimazolam in comparison to propofol for general anesthesia (GA) in patients undergoing surgery. METHODS: Electronic databases were searched from 15 May to 20 December 2023 for relevant publications which compared the outcomes reported with the newly approved remimazolam versus propofol in patients undergoing surgery. Relevant reported adverse drug events were the endpoints of this study. The statistical analysis was carried out using the latest version of the RevMan software. Data analysis was represented by risk ratio (RR) with 95% confidence intervals (CI). RESULTS: Sixteen studies with a total number of 1897 participants were included in this analysis; 1104 participants received remimazolam and 793 participants received propofol. The risks for hypotension (RR 0.50, 95% CI 0.43-0.58; P = 0.00001), hypoxemia (RR 0.43, 95% CI 0.19-0.99; P = 0.05), bradycardia (RR 0.53, 95% CI 0.36-0.78; P = 0.001), pain at injection site (RR 0.07, 95% CI 0.01-0.56; P = 0.01), and total adverse events (RR 0.33, 95% CI 0.24-0.47; P = 0.00001) were significantly lower with remimazolam. However, no significant differences were observed in terms of postoperative nausea and vomiting (RR 0.98, 95% CI 0.66-1.46; P = 0.93), dizziness (RR 0.42, 95% CI 0.11-1.57; P = 0.20), psychiatric symptoms (RR 1.09, 95% CI 0.45-2.67; P = 0.85), and respiratory depression (RR 0.81, 95% CI 0.24-2.76; P = 0.74). CONCLUSION: Our current analysis showed that the newly approved remimazolam was apparently associated with significantly fewer adverse drug events in comparison to propofol for GA in patients undergoing surgery. Therefore, this new drug should be further studied and more research with larger population sizes should be carried out to confirm this hypothesis.

Leadless pacemakers at 5-year follow-up: the Micra transcatheter pacing system post-approval registry.

BACKGROUND AND AIMS: Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed. METHODS: All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models. RESULTS: 1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001). CONCLUSIONS: Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection.

Prevalence of transthyretin cardiac amyloidosis in patients with high-degree AV block.

OBJECTIVE: Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative cardiac disorder caused by deposition of wild type or mutated transthyretin. As ATTR-CM is associated with conduction disease, we sought to determine its prevalence in patients with idiopathic high-degree atrioventricular (AV) block requiring permanent pacemaker (PPM) implantation. METHODS: Consecutive patients aged 70-85 years undergoing PPM implantation for idiopathic high-degree AV block between November 2019 and November 2021 were offered a 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scan. Demographics, comorbidities, electrocardiographic and imaging data from the time of device implantation were retrospectively collected. RESULTS: 39 patients (79.5% male, mean (SD) age at device implantation 76.2 (2.9) years) had a DPD scan. 3/39 (7.7%, all male) had a result consistent with ATTR-CM (Perugini grade 2 or 3). Mean (SD) maximum wall thickness of those with a positive DPD scan was 19.0 mm (3.6 mm) vs 11.4 mm (2.7 mm) in those with a negative scan (p=0.06). All patients diagnosed with ATTR-CM had spinal canal stenosis and two had carpal tunnel syndrome. CONCLUSIONS: ATTR-CM should be considered in older patients requiring permanent pacing for high-degree AV block, particularly in the presence of left ventricular hypertrophy, carpal tunnel syndrome or spinal canal stenosis.

Donepezil-induced bradycardia in a schizophrenic patient with comorbid neurocognitive disorder: a case report and review of the literature.

BACKGROUND: Trials of cholinergic and glutamatergic agents have improved cognition and memory for the geriatric schizophrenic population. Donepezil is an acetylcholinesterase inhibitor that improves cognition by preventing postsynaptic degradation of hippocampal acetylcholine in patients with mild-to-moderate dementia. Donepezil has been attributed to some adverse effects, especially gastrointestinal symptoms. However, cardiovascular adverse effects are not common as there remains a dearth of literature regarding donepezil-induced bradycardia. CASE REPORT: Hence, we present the case of a 70-year-old Hispanic female with past psychiatry history of schizophrenia who developed bradycardia and syncope following the commencement of low-dose donepezil in the inpatient unit and subsequent resolution with cessation. She had no prior cardiovascular symptoms or diagnosis. DISCUSSION: Considering there is no baseline cardiac monitoring requirement guideline for patients on Donepezil treatment, pre-assessment electrocardiogram is advised before the commencement of acetylcholinesterase inhibitors. Finally, routine monitoring of vital signs for at least the first 72 hours following the start of donepezil might be good proactive practice for all psychiatrists. Extending this practice to inpatient and outpatient service settings will be worthwhile.

The role of detailed medical history for the early diagnosis of familial bradycardia in a patient with associated atrial fibrillation: case report.

Background: Bradycardia represents a frequent reason for medical presentation and has a complex aetiology, including genetic disorders, like LMNA mutation. LMNA mutation is responsible for laminopathies, including LMNA -cardiomyopathy. Cardiac involvement is prevalent and is linked to dilated cardiomyopathy associated with conduction block, which is anticipated by bradyarrhythmia and supraventricular tachyarrhythmia. LMNA mutation carriers have higher risk for sudden cardiac death (SCD), malignant ventricular tachycardia, and extreme bradycardia. Case summary: A 48-year-old female presented for recurrent episodes of dizziness, lightheadedness, headache, and fatigue, occurring at rest. The past medical history was positive for hypertension and one episode of paroxysmal atrial fibrillation. The family medical history was positive; both children and the patient's mother are known with bradycardia. The electrocardiogram showed sinus bradycardia, and the echocardiography revealed a mild concentric hypertrophy of the left ventricle, associated with impaired relaxation diastolic dysfunction. The 24 h Holter monitoring recorded sinus bradycardia, multiple pauses, paroxysmal atrial fibrillation, and multiple episodes of junctional rhythm. The positive family medical history suggested a genetic link. Further, genetic testing was performed, revealing a mutation of the LMNA gene. Discussion: Despite apparently benign at the initial presentation, the correct diagnosis and management required detailed medical history and extensive investigation of both the patient and the first-degree relatives. As the LMNA mutation carriers have a higher risk for SCD and have a mortality risk of 40% at 5 years, we emphasize the role of early diagnosis and periodic monitoring for preventing the worsening of the condition. .

Carotid Sinus Tumor-Induced Positional Bradycardia and Hypotension After Extubation: A Case Report.

Regional progression of head and neck malignancies can lead to carotid sinus tumors, causing hemodynamic instability and carotid sinus syndrome (CSS). A 60-year-old male with tonsillar squamous cell carcinoma developed profound positional bradycardia and hypotension immediately after extubation following dental extraction. The patient developed recurrent episodes of positional bradycardia and hypotension, leading to eventual pacemaker placement. Further workup revealed a large mass in the left neck and necrotic cervical lymphadenopathy, indicating CSS from malignancy compression. This case highlights the need for consideration of CSS in patients with known head and neck malignancy, particularly when postural hypotension and bradycardia are present.

Breathing patterns and associated cardiovascular changes in intermittently breathing animals: (Partially) correcting a semantic quagmire.

Many animal species do not breathe in a continuous, rhythmic fashion, but rather display a variety of breathing patterns characterized by prolonged periods between breaths (inter-breath intervals), during which the heart continues to beat. Examples of intermittent breathing abound across the animal kingdom, from crustaceans to cetaceans. With respect to human physiology, intermittent breathing-also termed 'periodic' or 'episodic' breathing-is associated with a variety of pathologies. Cardiovascular phenomena associated with intermittent breathing in diving species have been termed 'diving bradycardia', 'submersion bradycardia', 'immersion bradycardia', 'ventilation tachycardia', 'respiratory sinus arrhythmia' and so forth. An examination across the literature of terminology applied to these physiological phenomena indicates, unfortunately, no attempt at standardization. This might be viewed as an esoteric semantic problem except for the fact that many of the terms variously used by different authors carry with them implicit or explicit suggestions of underlying physiological mechanisms and even human-associated pathologies. In this article, we review several phenomena associated with diving and intermittent breathing, indicate the semantic issues arising from the use of each term, and make recommendations for best practice when applying specific terms to particular cardiorespiratory patterns. Ultimately, we emphasize that the biology-not the semantics-is what is important, but also stress that confusion surrounding underlying mechanisms can be avoided by more careful attention to terms describing physiological changes during intermittent breathing and diving.