Papers by Christopher Johnsrude
JACC: Case Reports, Mar 1, 2023
Critical Care Medicine, 2018
www.ccmjournal.org Critical Care Medicine • Volume 46 • Number 1 (Supplement) Learning Objectives... more www.ccmjournal.org Critical Care Medicine • Volume 46 • Number 1 (Supplement) Learning Objectives: Procainamide (PA) is a class 1a antiarrhythmic that is efficacious in the treatment of post-operative tachyarrhythmias in children. Because of its hydrophilicity, the volume of distribution of PA in venoarterial extracorporeal membrane oxygenation (ECMO) is expected to increase. There are no reports on ECMO’s effect on PA dosing requirements and drug levels. Methods: We describe the case of a 2-month old who developed hemodynamically significant junctional ectopic tachycardia (JET) after ECMO cannulation following palliation of a hypoplastic aortic arch and complete atrioventricular canal defect. JET was refractory to amiodarone and esmolol infusions, but responded to IV procainamide monotherapy. A dose of 70 mcg/kg/min, the upper end of recommended dosing, achieved therapeutic levels (PA 3.5– 9.9 mcg/mL, PA+NAPA 5-18.5 mcg/mL [reference PA 4–10 mcg/ mL, PA+NAPA 10–30 mcg/mL]) and maintained sinus rhythm. The patient was decannulated on ECMO day 18 on minimal inotropic support of epinephrine 0.05 mcg/kg/min without notable changes in hepatic or renal function. The PA level was 8.8 mcg/mL prior to decannulation. Two hours after decannulation, the patient developed a wide QRS sinus rhythm with a stable heart rate and an acute decrease in blood pressure requiring an increase in epinephrine to 0.16 mcg/kg/min and the addition of norepinephrine. PA toxicity was suspected to be the cause of the acute clinical deterioration. PA level after decannulation was 15.9 mcg/mL (PA toxicity > 10–12 mcg/mL). IV sodium bicarbonate was administered and the PA dose was reduced, resulting in sinus rhythm with narrow QRS complexes and improved drug levels and blood pressures, allowing for subsequent weaning of catecholamine infusions. Results: This case highlights ECMO’s effect on PA volume of distribution and clearance and potentially serious clinical consequences resulting from changes in serum concentrations despite a constant infused PA dose. We recommend that a reduction in PA dosing be considered with closely monitored drug levels when patients are separated from ECMO.
Circulation-arrhythmia and Electrophysiology, Feb 1, 2021
Background: Implantable cardioverter defibrillators (ICD) are recommended for secondary preventio... more Background: Implantable cardioverter defibrillators (ICD) are recommended for secondary prevention after sudden cardiac arrest (SCA). The outcomes of pediatric patients receiving an ICD after SCA remain unclear. The objective of this study is to evaluate outcomes, future risk for appropriate shocks, and identify characteristics associated with appropriate ICD therapy during follow-up. Methods: Multicenter retrospective analysis of patients (age ≤21 years) without prior cardiac disease who received an ICD following SCA. Patient/device characteristics, cardiac function, and underlying diagnoses were collected, along with SCA event characteristics. Patient outcomes including complications and device therapies were analyzed. Results: In total, 106 patients were included, median age 14.7 years. Twenty (19%) received appropriate shocks and 16 (15%) received inappropriate shocks (median follow-up 3 years). First-degree relative with SCA was associated with appropriate shocks ( P <0.05). In total, 40% patients were considered idiopathic. Channelopathy was the most frequent late diagnosis not made at time of presentation. Neither underlying diagnosis nor idiopathic status was associated with increased incidence of appropriate shock. Monomorphic ventricular tachycardia (hazard ratio, 4.6 [1.2–17.3]) and family history of sudden death (hazard ratio, 6.5 [1.4–29.8]) were associated with freedom from appropriate shock in a multivariable model (area under the receiver operating characteristic curve, 0.8). Time from diagnoses to evaluation demonstrated a nonlinear association with freedom from appropriate shock ( P =0.015). In patients >2 years from implantation, younger age ( P =0.02) and positive exercise test ( P =0.04) were associated with appropriate shock. Conclusions: The risk of future device therapy is high in pediatric patients receiving an ICD after SCA, irrelevant of underlying disease. Lack of a definitive diagnosis after SCA was not associated with lower risk of subsequent events and does not obviate the need for secondary prophylaxis.
The Annals of Thoracic Surgery, Apr 1, 2009
Heart Rhythm, Nov 1, 2022
Heart Rhythm, May 1, 2022
Heartrhythm Case Reports, Oct 1, 2021
This report describes what we believe is the 1st reported case of indolent pacemaker infection's ... more This report describes what we believe is the 1st reported case of indolent pacemaker infection's causing abdominal ascites in a patient who has undergone a Fontan operation. Abdominal ascites in a Fontan patient is commonly due to protein-losing enteropathy, systemic venous thrombosis, myocardial dysfunction, chylous ascites, liver cirrhosis, or pancreatitis. Our patient, who had a functional single ventricle, presented with ascites 3 years after undergoing the Fontan operation and pacemaker implantation. After extensive testing and evaluation, we attributed the ascites to indolent infection of the abdominal pacemaker.
The Journal of innovations in cardiac rhythm management, Aug 1, 2022
Catheter ablation of the slow pathway to the atrioventricular node is generally a safe and effect... more Catheter ablation of the slow pathway to the atrioventricular node is generally a safe and effective treatment for atrioventricular nodal re-entry tachycardia (AVNRT). However, congenital anomalies of the inferior vena cava and superior draining veins can limit traditional catheter approaches to the right heart from femoral venous access and distort local anatomy within the triangle of Koch, necessitating alternative electrophysiology (EP) mapping and ablation strategies. Despite the widespread availability of non-fluoroscopic 3-dimensional imaging systems, many providers still rely on venography to describe unusual cardiovascular anatomy and fluoroscopy to position EP catheters when mapping and ablating the slow pathway. Herein, we report our experience with a pediatric patient with inducible AVNRT and atypical venous anatomy in whom slow pathway ablation was performed successfully without the use of fluoroscopy. In addition, we describe the modification of a novel mapping technique for targeting the slow pathway for ablation.
Heart Rhythm, May 1, 2022
Circulation, Nov 19, 2019
Fetal Diagnosis and Therapy, 2008
cardiac manifestations of immune-mediated damage include transient incomplete AV block [7] , junc... more cardiac manifestations of immune-mediated damage include transient incomplete AV block [7] , junctional ectopic tachycardia [8] , endocardial fibroelastosis [9, 10] , and cardiomyopathy [11, 12]. However, even in large series of isoimmune AV block, ventricular tachycardia (VT) is rarely diagnosed [13]. Whether this is because VT is not a common manifestation of disease, or VT has been incorrectly diagnosed by M-Mode/Doppler technology, is not known. We had the opportunity to use fMCG to diagnose VT in a fetus with isoimmune AV block, and followed this infant after delivery. Case Report Bradycardia was detected in a female fetus during a routine obstetric ultrasound performed on a 36-year-old G8P5A2 mother at 25 weeks gestation. The mother had symptoms of joint pain and unexplained rash, but did not have diagnosis of a specific connective tissue disease. The fetal echocardiogram performed several
Journal of Heart and Lung Transplantation, Apr 1, 2006
Giant cell myocarditis (GCM) is an organ-specific, autoimmune disease that infrequently affects c... more Giant cell myocarditis (GCM) is an organ-specific, autoimmune disease that infrequently affects children and generally has a more aggressive (often fatal) course than other forms of myocarditis. No data are available about the epidemiology of GCM in children. We describe a 13-year-old girl who presented with ventricular tachycardia and rapid hemodynamic deterioration that required extracorporeal membrane oxygenation (ECMO) as a bridge to heart transplantation. Histopathologic examination of the explanted heart revealed GCM. We review the demographic features, clinical course and post-transplant immunosuppressive therapy of all patients aged 19 years and younger reported to have had GCM.
Canadian Journal of Cardiology, 2021
Journal of Experimental Biology, 1985
Net forces and velocities resulting from in situ contractions of the myotomal musculature on one ... more Net forces and velocities resulting from in situ contractions of the myotomal musculature on one side of the body were measured at the hypural bones. Forces, velocities and power were determined with the body bent into a range of postures typical of those observed during fast-start swimming. For trout averaging 0·178 m in length and 0·0605 kg in body mass, the muscle system exerts a maximum normal force of 2·2 N at the base of the caudal fin. This force is equivalent to 11·8 kN m−2 based on the mean crosssectional area of the myotomal muscle. The maximum velocity was 1·11 ms−1, and the maximum mechanical power output, 0·64W, or 42·4 W kg−1 muscle. Based on estimates of swimming resistance, these results would suggest acceleration rates of 7·5 to 16·5 ms−2, similar to averages observed during fast-starts. Maximum sprint speeds would range from 6·5 to 17·8 body lengths s−1, spanning the range of maximum speeds reported in the literature. It is suggested that maximum speed is limited b...
Journal of Pediatric Gastroenterology & Nutrition, 1999
Fish Physiology and Biochemistry, 1988
The length and mean cross-sectional area of the myotome of rainbow trout, Salmo gairdneri, scale ... more The length and mean cross-sectional area of the myotome of rainbow trout, Salmo gairdneri, scale isometrically with total length (L, cm) and L 2 respectively for fish from 5 to 35 cm in length. The net maximum force, (F, kN.m-2) developed by a single twitch of the in situ myotome on one side of the body, and measured normal to the hypural complex increased as; F = 1.05 x 10-3.L 2.6, and maximum lateral velocity (W, re.s-I) at the hypural plate as; W = 0.29 L-~ Maximum power (P, W) increased as; P = 7.64 x 10-5.L 3-~ Acceleration rates predicted from these data do not agree well with observations. In addition, except for small fish, predicted maximum speeds differed from those calculated from minimum twitch times of excised muscle blocks and stride length, the popular method for estimating maximum speed. It is suggested that temporal summation of twitches must occur in larger fish. This could provide forces matched to inertial loads which are important in fitness-critical maneuvers.
Europace, Jan 31, 2017
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an ion channelopathy characterize... more Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an ion channelopathy characterized by ventricular arrhythmia during exertion or stress. Mutations in RYR2-coded Ryanodine Receptor-2 (RyR2) and CASQ2-coded Calsequestrin-2 (CASQ2) genes underlie CPVT1 and CPVT2, respectively. However, prognostic markers are scarce. We sought to better characterize the phenotypic and genotypic spectrum of CPVT, and utilize molecular modelling to help account for clinical phenotypes.
The American Journal of Emergency Medicine
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Papers by Christopher Johnsrude