An under-recognized cause of pacemaker-mediated rhythm.
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ABSTRACT:
SUBMITTER: Vazirani-Ballesteros R
PROVIDER: S-EPMC10516355 | biostudies-literature | 2023 Sep
REPOSITORIES: biostudies-literature
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An under-recognized cause of pacemaker-mediated rhythm.
Vazirani-Ballesteros Ravi R Gómez Eduardo Martínez EM Fernández-Jiménez Rodrigo R
European heart journal. Case reports 20230908 9
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Project description:Spontaneous coronary artery dissection (SCAD) is a rare condition that is often underdiagnosed given limitations of conventional cineangiography. In addition to the diagnostic challenge, the condition poses a major therapeutic dilemma given paucity of literature to guide management. We report the case of a 55-year-old woman, who presented with acute coronary syndrome. Coronary angiography at the time of the index hospitalization revealed type 2 SCAD. She was managed conservatively. Repeat coronary angiography three months later showed complete resolution of the previously noted dissection. Because of the high association between SCAD and fibromuscular dysplasia (FMD), a cross-sectional imaging was performed in this case, which ruled out underlying FMD. The patient has been followed longitudinally since her index event and has had no reported recurrences.
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| S-EPMC11903589 | biostudies-literature
Project description:BackgroundInfection-related acute kidney injury (AKI) is an important preventable cause of morbidity and mortality in the tropical region. The prevalence and outcome of kidney involvement, especially AKI, in scrub typhus is not known. We investigated all patients with undiagnosed fever and multisystem involvement for scrub typhus and present the pattern of renal involvement seen.MethodsFrom September 2011 to November 2012, blood samples of all the patients with unexplained acute febrile illness and/or varying organ involvement were evaluated for evidence of scrub typhus. A confirmed case of scrub typhus was defined as one with detectable Orientia tsutsugamushi deoxyribonucleic acid (DNA) in patient's blood sample by nested polymerase chain reaction (PCR) targeting the gene encoding 56-kDa antigen and without any alternative etiological diagnosis. Renal involvement was defined by demonstration of abnormal urinalysis and/or reduced glomerular filtration rate. AKI was defined as per Kidney Disease: Improving Global Outcomes (KDIGO) definition.ResultsOut of 201 patients tested during this period, 49 were positive by nested PCR for scrub typhus. Mean age of study population was 34.1±14.4 (range 11-65) years. Majority were males and a seasonal trend was evident with most cases following the rainy season. Overall, renal abnormalities were seen in 82% patients, 53% of patients had AKI (stage 1, 2 and 3 in 10%, 8% and 35%, respectively). The urinalysis was abnormal in 61%, with dipstick positive albuminuria (55%) and microscopic hematuria (16%) being most common. Acute respiratory distress syndrome (ARDS) and shock were seen in 57% and 16% of patients, respectively. Hyperbilirubinemia was associated with AKI (p = 0.013). A total of 8 patients (including three with dialysis dependent AKI) expired whereas rest all made uneventful recovery. Jaundice, oliguria, ARDS and AKI were associated with mortality. However, after multivariate analysis, only oliguric AKI remained a significant predictor of mortality (p = 0.002).ConclusionsScrub typhus was diagnosed in 24% of patients presenting with unexplained febrile illness according to a strict case definition not previously used in this region. Renal abnormalities were seen in almost 82% of all patients with evidence of AKI in 53%. Our finding is contrary to current perception that scrub typhus rarely causes renal dysfunction. We suggest that all patients with unexplained febrile illness be investigated for scrub typhus and AKI looked for in scrub typhus patients.
| S-EPMC3907360 | biostudies-literature
Project description:Inspiration is the inexorable active phase of breathing. The brainstem pre-Bötzinger complex (preBötC) gives rise to inspiratory neural rhythm, but its underlying cellular and ionic bases remain unclear. The long-standing "pacemaker hypothesis" posits that the persistent Na+ current (INaP) that gives rise to bursting-pacemaker properties in preBötC interneurons is essential for rhythmogenesis. We tested the pacemaker hypothesis by conditionally knocking out and knocking down the Scn8a (Nav1.6 [voltage-gated sodium channel 1.6]) gene in core rhythmogenic preBötC neurons. Deleting Scn8a substantially decreases the INaP and abolishes bursting-pacemaker activity, which slows inspiratory rhythm in vitro and negatively impacts the postnatal development of ventilation. Diminishing Scn8a via genetic interference has no impact on breathing in adult mice. We argue that the Scn8a-mediated INaP is not obligatory but that it influences the development and rhythmic function of the preBötC. The ubiquity of the INaP in respiratory brainstem interneurons could underlie breathing-related behaviors such as neonatal phonation or rhythmogenesis in different physiological conditions.
| S-EPMC10528911 | biostudies-literature
Project description:The rhythmic motor pathway activation by pacemaker neurons or circuits in the brain has been proposed as the mechanism for the timing of motor coordination, and the abnormal potentiation of this mechanism may lead to a pathological tremor. Here, we show that the potentiation of Ca(V)3.1 T-type Ca(2+) channels in the inferior olive contributes to the onset of the tremor in a pharmacological model of essential tremor. After administration of harmaline, 4- to 10-Hz synchronous neuronal activities arose from the IO and then propagated to cerebellar motor circuits in wild-type mice, but those rhythmic activities were absent in mice lacking Ca(V)3.1 gene. Intracellular recordings in brain-stem slices revealed that the Ca(V)3.1-deficient inferior olive neurons lacked the subthreshold oscillation of membrane potentials and failed to trigger 4- to 10-Hz rhythmic burst discharges in the presence of harmaline. In addition, the selective knockdown of Ca(V)3.1 gene in the inferior olive by shRNA efficiently suppressed the harmaline-induced tremor in wild-type mice. A mathematical model constructed based on data obtained from patch-clamping experiments indicated that harmaline could efficiently potentiate Ca(V)3.1 channels by changing voltage-dependent responsiveness in the hyperpolarizing direction. Thus, Ca(V)3.1 is a molecular pacemaker substrate for intrinsic neuronal oscillations of inferior olive neurons, and the potentiation of this mechanism can be considered as a pathological cause of essential tremor.
| S-EPMC2890811 | biostudies-other
Project description:Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of severe immune activation with macrophage and T-cell infiltration resulting in, multi organ damage. HLH may be primary or secondary in etiology. A high index of suspicion is essential for early diagnosis and treatment. Diagnostic criteria need to be refined and newer treatment options to be explored in order to improve survival especially in adult HLH and malignancy-associated HLH (M-HLH). We report a case of malignancy associated HLH (M-HLH) in adult treated on one of the only FDA-approved protocols for adult HLH to highlight the diagnostic and therapeutic challenges of this disease entity.
| S-EPMC5219626 | biostudies-literature
Project description:AimsBeta-blockers are proven to improve survival among patients with heart failure with reduced ejection fraction. Their efficacy in patients with heart failure with reduced ejection fraction and pacemaker devices has not been demonstrated. Our aim was to test the hypothesis that beta-blocker therapy is associated with improved survival in patients with chronic heart failure and a pacemaker rhythm on electrocardiogram (ECG).Methods and resultsThis is a post hoc analysis from the GISSI-HF randomized clinical trial. We evaluated efficacy of beta-blockers by creating Cox proportional hazards models adjusting for pacemaker rhythm and heart rate, among other variables. Interactions between pacemaker rhythm, heart rate, and beta-blocker were also examined. Of the 6975 patients enrolled in the GISSI-HF trial, 813 (11.7%) had a pacemaker rhythm on baseline ECG. Of these 813 patients, 511 (62.9%) were receiving beta-blocker therapy. The effect of beta-blocker therapy on mortality was assessed using multivariable Cox proportional hazards adjusted for 27 co-variates. In the whole cohort, beta-blocker therapy was significantly associated with reduced mortality (hazard ratio 0.79 [0.72-0.87], P < 0.001), without interaction between beta-blockers, pacemaker rhythm and heart rate. Beta-blocker therapy was beneficial in the sub-group restricted to baseline pacemaker rhythm (hazard ratio 0.62 [0.49-0.79], P < 0.001).ConclusionsBeta-blocker therapy is associated with improved survival among patients with heart failure and a pacemaker rhythm on ECG. Further studies are necessary to analyse differences between atrial and ventricular pacemakers.
| S-EPMC10192283 | biostudies-literature
Project description:Many patients requiring a pacemaker have persistent hypertension with systolic blood pressures above recommended levels. We evaluated a pacemaker-based Programmable Hypertension Control (PHC) therapy that uses a sequence of variably timed shorter and longer atrioventricular intervals. Patients indicated for dual-chamber pacing with office systolic blood pressure (oSBP) >150 mm Hg despite stable medical therapy were implanted with a Moderato™ pulse generator that delivers PHC therapy. Patients were followed for 1 month (Run-In period) with conventional pacing; those with persistent oSBP >140 mm Hg were included in the study and had PHC therapy activated. The co-primary efficacy end points were changes in 24-hour ambulatory systolic blood pressure and oSBP between baseline and 3 months. Safety was assessed by tracking adverse events. Thirty-five patients met the initial inclusion criteria and underwent Moderato implantation. At 1 month, oSBP was <140 mm Hg in 7 patients who were excluded. PHC was activated in the remaining 27 patients with baseline office blood pressure 166±11/80±10 mm Hg despite an average of 3.2 antihypertensive medications. During the Run-In period, oSBP and 24-hour ambulatory systolic blood pressure decreased by 8±13 and 5±12 mm Hg (P<0.002), respectively. Compared with pre-PHC activation measurements, oSBP decreased by another 16±15 mm Hg and 24-hour ambulatory systolic blood pressure decreased by an additional 10±13 mm Hg (both P<0.01) at 3 months. No device-related serious adverse effects were noted. In pacemaker patients with persistent hypertension despite medical therapy, oSBP and 24-hour ambulatory systolic blood pressure are decreased by PHC therapy. Initial indications are that this therapy is a safe and promising therapy for such patients. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02282033.
| S-EPMC5779015 | biostudies-literature