Myocarditis complicated by complete atrioventricular block: nine years' experience in a medical center

The cardiac conduction system: History, development, and disease

The heart is the first organ to form during embryonic development, establishing the circulatory infrastructure necessary to sustain life and enable downstream organogenesis. Critical to the heart's function is its ability to initiate and propagate electrical impulses that allow for the coordinated contraction and relaxation of its chambers, and thus, the movement of blood and nutrients. Several specialized structures within the heart, collectively known as the cardiac conduction system (CCS), are responsible for this phenomenon. In this review, we discuss the discovery and scientific history of the mammalian cardiac conduction system as well as the key genes and transcription factors implicated in the formation of its major structures. We also describe known human diseases related to CCS development and explore existing challenges in the clinical context.

Complete heart block associated with hepatitis A infection in a female child with fatal outcome

Hepatitis A virus (HAV) infection can cause extra-hepatic manifestations like myocarditis. An 8-year-old female with HAV infection presented with fever, abdominal pain, vomiting, and icterus. She developed viral myocarditis with complete AV dissociation on ECG and was treated with a temporary pacemaker, but her condition worsened, and she died. Hepatitis A viral infection can be associated with viral myocarditis and complete heart block that can lead to cardiogenic shock and death eventually.

Treatment strategy for acute myocarditis in pediatric patients requiring emergency intervention

BACKGROUND

Patients with acute myocarditis present with a wide range of symptoms. Treatment strategies for pediatric patients with circulatory failure comprise extracorporeal membrane oxygenation (ECMO), emergency temporary pacing, and pharmacotherapy. However, they remain controversial. ECMO is an effective treatment but gives rise to several complications; the goal is therefore to avoid excessive treatment as much as possible. We aimed to evaluate the importance of electrocardiogram findings in differentiating severity and establish an appropriate treatment strategy in pediatric patients with acute myocarditis who required emergency interventions.

METHODS

This retrospective study enrolled pediatric patients admitted to and treated in our hospital for acute myocarditis between April 1983 and December 2021. Patients were retrospectively divided into whether circulatory failure occurred (ECMO or temporary pacing was needed; emergency intervention group) or not (pharmacotherapy alone).

RESULTS

Of the 26 pediatric patients, 11 experienced circulatory failure while 15 did not. In the circulatory failure group, six patients were treated with ECMO (ECMO group) and five patients with temporary pacing (pacing group). In the pacing group, all patients were diagnosed with complete and/or advanced atrioventricular block (CAVB and/or advanced AVB) and narrow QRS. Furthermore, these patients improved only with temporary pacing and pharmacotherapy, without requiring ECMO. Wide QRS complexes (QRS ≥ 0.12 ms) with ST-segment changes were detected on admission in five of six patients in the ECMO group and none in the pacing group (P = 0.015). Although all patients in the ECMO group experienced complications, none did in the pacing group (P < 0.008).

CONCLUSIONS

Regarding emergency intervention for acute myocarditis, ECMO or temporary pacing could be determined based on electrocardiogram findings, particularly wide QRS complexes with ST-segment changes on admission. It is important to promptly introduce ECMO in patients with wide QRS complexes with ST-segment changes, however, patients with CAVB and/or advanced AVB and narrow QRS could improve without undergoing ECMO. Therefore, excessive treatment should be avoided by separating ECMO from temporary pacing based on electrocardiogram findings on admission.

Clinical profile and outcomes of semi-permanent pacing in a tertiary care institute in southern India

BACKGROUND

Semi-permanent pacing (SPP) includes the placement of a permanent lead through the internal jugular vein and connection to a pulse generator on the skin outside the venous access site.

AIM

To evaluate the clinical profile and outcomes of semi-permanent pacing in a tertiary care institute in Southern India.

METHODS

This is a retrospective observational study. All patients admitted and requiring management with semi-permanent pacing from January 2017 to June 2020 were included.

RESULTS

From January 2017 to June 2020, 20 patients underwent semi-permanent pacing (SPP) with a median age of 54 (21-74) years. Males comprised a majority of the patients (55%). Hypertension was noted in 50% of patients and 30% were diabetic. The right internal jugular vein was the most common access in 95% of patients. The most common indication for semi-permanent pacing was pocket site infection in 30% of patients. There were no procedural complications. The median duration on SPP was 7 (5-14) days and the median duration of hospital stay was 13 (8-21) days. Permanent pacemaker implantation was done in 55% of patients. Mortality in our study group was 15% with 10% dying due to cardiogenic shock (post resuscitated cardiac arrest) and 5% dying due to non-cardiac cause (Epidural hematoma).

CONCLUSION

In our study, semi-permanent pacing was noted to be a safe procedure and was more commonly indicated in emergent conditions with complete heart block secondary to underlying reversible causes and in the management of pocket site infection.

Diagnosis and Management of Myocarditis: An Evidence-Based Review for the Emergency Medicine Clinician

BACKGROUND

Myocarditis is a potentially fatal condition that can be misdiagnosed in the emergency department (ED) setting.

OBJECTIVE

The purpose of this narrative review article is to provide a summary of the background, pathophysiology, diagnosis, and management of myocarditis, with a focus on emergency clinicians.

DISCUSSION

Myocarditis occurs when inflammation of the heart musculature causes cardiac dysfunction. Symptoms may range from mild to severe and are often preceded by a viral prodrome. Laboratory assessment and an electrocardiogram can be helpful for the diagnosis, but echocardiography is the ideal test in the ED setting. Some patients may also require advanced imaging, though this will often occur during hospitalization or follow-up. Treatment is primarily focused on respiratory and hemodynamic support. Initial hemodynamic management includes vasopressors and inotropes, whereas more severe cases may require an intra-aortic balloon pump, extracorporeal membrane oxygenation, or a ventricular assist device. Nonsteroidal anti-inflammatory drugs should be avoided while intravenous immunoglobulin is controversial.

CONCLUSION

Myocarditis is a serious condition with the potential for significant morbidity and mortality. It is important for clinicians to be aware of the current evidence regarding the diagnosis, management, and disposition of these patients.

Permanent pacemaker implantation and its predictors in patients admitted for complete atrioventricular block: a report from the Tokyo Cardiovascular Care Unit Network multi-center registry

Little is known about the permanent pacemaker implantation rate and predictors of permanent pacemaker implantation in patients admitted for complete atrioventricular block (cAVB). The present study was a retrospective analysis based on a multicenter cohort of 797 patients with cAVB (mean age: 79.6 ± 10.7 years; males: 48.4%) registered with the Tokyo Cardiovascular Care Unit Network multicenter registry between 2013 and 2016. Secondary cAVB due to acute coronary syndrome was excluded. The permanent pacemaker implantation rate was 82.9%. Multivariable logistic regression analysis revealed that systolic blood pressure (SBP) > 140 mmHg [odds ratio (OR) 2.10; 95% confidence interval (CI) 1.38-3.22; P < 0.001], male gender (OR 1.63; 95% CI 1.07-2.49; P = 0.023), and left ventricular ejection fraction (LVEF) ≥ 50% (OR 2.19; 95% CI 1.16-2.06; P = 0.016) were predictors of permanent pacemaker implantation while pre-admission β-blocker use (OR 0.28; 95% CI 0.17-0.47; P < 0.001) was associated with a lower risk of permanent pacemaker implantation. Reversible cAVB was not rare in patients admitted for cAVB. Data on SBP on admission, gender, LVEF, and pre-admission β-blocker use may be important for assessing the requirement for permanent pacemaker implantation in the emergency care setting.

Hypoperfusion With Vomiting, Abdominal Pain, or Dizziness and Convulsions: An Alert to Fulminant Myocarditis in Children

Objective: To investigate the clinical features, treatment methods, and outcomes of fulminant myocarditis (FM) in children. Methods: The clinical data of 23 children with FM hospitalized in the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China (Anhui Provincial Hospital) and Anhui Provincial Children's Hospital from January 2011 to September 2019 were retrospectively analyzed. Results: Among the 23 patients analyzed, 10 were male and 13 were female. The patients aged from 6 months to 14 years old (6.5 ± 3.4 years), and 18 patients were over 3 years old. There were 14 cases with respiratory symptoms, 16 cases with gastrointestinal symptoms, 15 cases with neurological symptoms, and 19 cases with hypoperfusion manifestations. Creatine kinase MB (CK-MB) and cardiac troponin I (CTnI) levels were increased in 19 and 21 cases, respectively. Electrocardiography (ECG) showed ST-T changes in 18 cases and atrioventricular blocks (AVB) in 15 cases. Echocardiography (ECHO) showed cardiac chamber enlargement (CCE) in eight cases, left ventricular systolic dysfunction in five cases, decrease in left ventricular ejection fraction (LVEF) in four cases, reduction in wall motion in two cases, and pericardial effusion in seven cases. Intravenous immunoglobulin (IVIG) and glucocorticoids were administered to 19 and 20 patients, respectively. Fourteen patients were treated with temporary pacemakers, one patient received extracorporeal membrane oxygenation (ECMO), one patient received continuous renal replacement therapy (CRRT), and one patient received ECMO combined with CRRT. Twenty patients improved at discharge, and three patients died. Conclusion: Preschool and school-age children showing hypoperfusion symptoms, such as paleness, cold, clammy limbs, and capillary refill time (CRT) extension, accompanied by vomiting, abdominal pain, dizziness, convulsions, and other symptoms, should be carefully examined for FM. CK-MB, CTnI, ECG, and echocardiogram need to be performed at the earliest opportunity. In the early stages of FM, vital signs should be actively monitored, high-dose IVIG and glucocorticoids should be administered, and life support technologies such as temporary pacemakers, ECMO, and CRRT should be used to increase the survival rate of children with FM as needed.

Left bundle branch block: Epidemiology, etiology, anatomic features, electrovectorcardiography, and classification proposal

In left bundle branch block (LBBB), the ventricles are activated in a sequential manner with alterations in left ventricular mechanics, perfusion, and workload resulting in cardiac remodeling. Underlying molecular, cellular, and interstitial changes manifest clinically as changes in size, mass, geometry, and function of the heart. Cardiac remodeling is associated with progressive ventricular dysfunction, arrhythmias, and impaired prognosis. Clinical and diagnostic notions about LBBB have evolved from a simple electrocardiographic alteration to a critically important finding affecting diagnostic and clinical management of many patients. Advances in cardiac magnetic resonance imaging have significantly improved the assessment of patients with LBBB and provided additional insights into pathophysiological mechanisms of left ventricular remodeling. In this review, we will discuss the epidemiology, etiologies, and electrovectorcardiographic features of LBBB and propose a classification of the conduction disturbance.

A retrospective study: cardiac MRI of fulminant myocarditis in children-can we evaluate the short-term outcomes?

Background

Fulminant myocarditis (FM) is an inflammatory disease of the myocardium that results in ventricular systolic dysfunction and causes acute-onset heart failure. Cardiac magnetic resonance (CMR) has become the primary noninvasive tool for the diagnosis and evaluation of myocarditis. The aim of our study was to assess the CMR findings at different course of FM and the short-term outcomes of fulminant myocarditis (FM) in children.

Methods

Eight FM children with CMR examinations were included in our study. Initial baseline CMR was performed 10 days (range, 7–20 days) after onset of FM and follow-up CMR after 55 days (range, 33–75 days). Cardiac morphology and function and myocardial tissue characterization at baseline and follow-up CMR were compared using paired T-test and Mann–Whitney U test. The clinical data and initial CMR findings were also compared to predict short-term outcomes.

Results

The median age of eight FM children was 8.5 years old (range, 3–14). The initial CMR findings were most common with early gadolinium enhancement (EGE, 100%), followed by signal increasing on T2WI and late gadolinium enhancement (LGE, 87.5%), increased septal thickness (75.0%) and increased left ventricle ejection fraction (LVEF, 50.0%). Only three LGE (37.5%), one signal increasing on T2WI (12.5%) and one increased LVEF (12.5%) were found at follow-up. Statistically significant differences were found between initial and follow-up CMR abnormalities in the septal thickness, left ventricular end-diastolic diameter (LVEDD), end-systolic volume (ESV), LVEF, left ventricular mass, T2 ratio and LGE area (P = 0.011, P = 0.042, P = 0.016, P = 0.001, P = 0.003, P = 0.011, P = 0.020). The children with full recovery performed higher incidence of III° atrioventricular block (AVB, five cases VS 0 case) and smaller LGE area (104.0 ± 14.5 mm² VS 138.0 ± 25.2 mm²) at baseline CMR.

Discussion

The CMR findings of FM in children were characteristic and useful for early diagnosis. Full recovery of clinical manifestations, immunological features and CMR findings could be found in most FM children. The presence of III° AVB and smaller LGE area at baseline CMR might indicate better short-term outcomes.

Impact of Extracorporeal Membrane Oxygenation on Acute Fulminant Myocarditis-related Hemodynamic Compromise Arrhythmia in Children

BACKGROUND

Acute fulminant myocarditis (AFM) commonly presents as abrupt cardiogenic shock with or without dysrhythmia. This study evaluated the impact of extracorporeal membrane oxygenation (ECMO) on AFM-related hemodynamic compromise dysrhythmias. We also reported the clinical experience of AFM at our hospital.

METHODS

Eighteen children diagnosed with AFM were enrolled. Demographic variables, laboratory data, and clinical courses were reviewed. Thirteen surviving patients with hemodynamic compromise arrhythmia [complete atrioventricular block (CAVB) or ventricular tachycardia (VT)] during hospitalization were divided into Group A (ECMO group; n = 7) and Group B (non-ECMO group; n = 6).

RESULTS

The overall survival rate was 78% (14/18). There were no cases of mortality after ECMO was introduced at our hospital. Common symptoms at diagnosis included general malaise (94%), gastrointestinal symptoms (89%), chest pain (56%), shortness of breath (56%), and seizure/syncope (56%). In addition to abnormal cardiac enzyme levels, all patients displayed elevated alanine aminotransferase levels during early disease stages. Electrocardiography at diagnosis revealed dysrhythmia in 15 patients, namely, CAVB in 11 patients (61%) and VT in four patients (22%). During hospitalization, the dysrhythmia shifted from CAVB to VT in 10 patients and from sinus tachycardia to VT in one patient. New episodes of VT were common (overall occurrence rate, 83%). Although myocardial damage and dysfunction were more severe in Group A, the time to rhythm recovery in this group was shorter than that in Group B (median time, 1.7 days vs. 7.35 days, p = 0.045). All surviving patients had normal ventricular function at 6-month follow-up.

CONCLUSION

Hemodynamic compromise arrhythmia is common in AFM patients and may cause rapid deterioration. Simply correcting sinus rhythm is not always sufficient because of myocardium instability. Timely use of ECMO can improve the survival rate and shorten the time to recapture sinus rhythm in AFM patients with CAVB or VT.

In-hospital arrhythmia development and outcomes in pediatric patients with acute myocarditis

Cardiac arrhythmias are a complication of myocarditis. There are no large studies of in-hospital arrhythmia development and outcomes in pediatric patients with acute myocarditis. This was a retrospective 2-center review of patients ≤21 years hospitalized with acute myocarditis from 1996 to 2012. Fulminant myocarditis was defined as the need for inotropic support within 24 hours of presentation. Acute arrhythmias occurred at presentation and subacute after admission. Eighty-five patients (59% men) presented at a median age of 10 years (1 day to 18 years). Arrhythmias occurred in 38 patients (45%): 16 acute, 12 subacute, and 9 acute and subacute (1 onset unknown). Arrhythmias were associated with low voltages on the electrocardiogram (14 of 34, 41% vs 6 of 47, 13%; odds ratio [OR] 4.78, 95% confidence interval [CI] 1.60 to 14.31) and worse outcome (mechanical support, orthotopic heart transplant, or death; OR 7.59, 95% CI 2.61 to 22.07) but were not statistically significantly associated with a fulminant course, ST changes, initial myocardial function, lactate, creatinine level, C-reactive protein and/or erythrocyte sedimentation rate, or troponin I level, after adjusting for multiple comparisons. Subacute arrhythmias were associated with preceding ST changes (10 of 15, 67% vs 15 of 59, 25%, OR 5.87, 95% CI 1.73 to 19.93). All patients surviving to discharge had arrhythmia resolution or control before discharge (10 on antiarrhythmic), with 1 exception (patient with complete heart block requiring a pacemaker). At 1-year follow-up, there were 3 recurrences of ventricular arrhythmias, but no arrhythmia-related mortality. In conclusion, arrhythmias are common in pediatric patients with myocarditis, occurring in nearly 1/2 of all hospitalized children and are associated with a worse outcome. Early identification of subacute arrhythmias using electrocardiographic changes may help management. A majority of patients do not require continued postdischarge arrhythmia treatment.

Clinical characteristics and long-term outcome of acute myocarditis in children

The clinical course of acute myocarditis (AM) in children varies from being asymptomatic to causing sudden cardiac death. The aim of this study was to clarify the clinical characteristics and the long-term outcome of AM in children. We enrolled 24 children (aged from 0.1 to 14.6 years, median 8.4 years), who were diagnosed as AM between 1978 and 2010. The maximum follow-up period was 31 years (median 7 years). We retrospectively investigated their clinical course of AM. We also analyzed survival rate, persistence of decreased left ventricular ejection fraction (LVEF) by two-dimensional echocardiogram (2DE), and persistence of complete atrioventricular block (CAVB) by the Kaplan-Meier method. Furthermore, using univariate analysis we analyzed the factors that influenced the outcome. The survival rate was 86 % (95 % confidence interval (CI), 65-96) at 30 years. The persistence rate of LVEF less than 60 % at 1 month, 1 years, and 3 years was 44 % (95 % CI, 22-68), 36 % (95 % CI, 17-62) and 18 % (95 % CI, 3-59), respectively (n = 16), and the persistence of CAVB at 10 days was 36 % (95 % CI, 14-66, n = 11). In six patients with persistence of wide QRS (>100 ms), there were one acute death, two late deaths, and one orthotopic heart transplantation. The 30-year survival rate for six patients with wide QRS and 17 patients without wide QRS in the late phase was 50 % (95 % CI, 17-83) and 100 % (P = 0.0078), respectively. The factors in the acute phase influenced on the outcome were log creatine phosphokinase (CPK) 4.60 (95 % CI, 1.64-29.26, P = 0.001), appearance of ventricular tachycardia 19.71 (95 % CI, 2.50-399.9, P = 0.005), and LVEF 0.91 (95 % CI, 0.81-0.98, P = 0.015), respectively. The predictors of poor outcome in children with AM were high serum CPK, appearance of ventricular tachycardia and low LVEF in the acute phase, and persistence of wide QRS in the late phase. The long-term survival rate of children without these factors was fair.

Seizures and syncope due to complete atrioventricular block in a patient with acute myocarditis with a normal left ventricular systolic function

A 43-year-old man was admitted to our hospital presenting with seizures and syncope. He had a history of a cold with a fever of 39°C occurring three days earlier. Electrocardiography (ECG) showed complete atrioventricular block (AV block) with a maximum pause of 32 seconds, for which temporary pacing was performed. Echocardiography showed mild hypertrophy of the left ventricle (LV) with a normal ejection fraction of 61%. Coronary angiography showed normal coronary arteries. Then, an endomyocardial biopsy was performed, the results of which indicated a diagnosis of acute myocarditis. After admission, the complete atrioventricular block disappeared together with normalization of the LV wall thickness.

Clinical presentation of pediatric myocarditis in Taiwan

BACKGROUND

The purposes of this study were to characterize the symptoms and signs of children with myocarditis at the time of presentation to the hospital and to identify the predictors of death.

METHODS

This was a 5-year retrospective study in a tertiary hospital. We collected demographic data and clinical symptoms and signs when children with myocarditis presented at the hospital. The outcome for patient was classified as either survival or death, and the predictors of death were identified.

RESULTS

Over the 5-year period, 27 children (14 boys and 13 girls) met the definition of clinical myocarditis. The mean age of the myocarditis patients was 9.1±5.1 years (range, 0.08-17.9 years), and the maximum age was 10-12 years. The most common presentation was gastrointestinal symptoms. We used extracorporeal membrane oxygenation on nine (33%) children, and pacemaker was implanted in eight (30%). Six (22%) children died in this study, and only one of them was younger than 6 years. The poor prognosis predictors were gastrointestinal symptoms, hepatomegaly, and hypotension.

CONCLUSIONS

Pediatric myocarditis presents primarily with gastrointestinal symptoms in Taiwan. Careful check of heart rhythm may provide a useful objective marker of myocarditis. The predictors of a poor prognosis were gastrointestinal symptoms, hepatomegaly, and hypotension.

The follow-up evaluation of electrocardiogram and arrhythmias in children with fulminant myocarditis

BACKGROUND

Fulminant myocarditis involves various serious arrhythmias that sometimes have lethal consequences. The purpose of the present study was to investigate the electrocardiogram findings, arrhythmogenicity and abnormalities of the cardiac conduction system in children with fulminant myocarditis.

METHODS AND RESULTS

Between 1999 and 2008, 7 consecutive patients (mean age: 7 years) who suffered from fulminant myocarditis were included in the study. A 12-lead electrocardiogram, Holter monitoring and signal-averaged electrocardiograms were performed and compared between the acute, convalescent, and recovery phases in the 4 surviving patients. Also, electrophysiologic assessment was carried out during the convalescent phase. Five out of 7 patients developed complete atrioventricular block, 3 developed ventricular tachycardia, 2 had cardiac arrest, 2 developed sinus tachycardia, 1 developed ventricular fibrillation, 1 had advanced atrioventricular block, and 1 developed sick sinus syndrome. Among the surviving patients, all arrhythmias resolved during the convalescent and remote phases. No atrial or ventricular arrhythmias were induced in any patients during the programmed stimulation study. In the convalescent phase, no arrhythmias could be induced and there were no signs of any conduction abnormalities on electrophysiological assessment.

CONCLUSIONS

Close follow-up should be performed to observe for the occurrence of any new arrhythmias and/or a decrease in cardiac function in children with fulminant myocarditis.

Arrhythmogenic causes of chest pain in children

Although cardiac causes of chest pain in children are infrequent, arrhythmias are implicated in most cardiac related cases. The most common arrhythmias associated with chest pain are supraventricular tachycardias, but more ominous rhythms, such as ventricular tachycardia or bradycardias, can manifest as chest pain. Investigation of all children with chest pain suspected of arrhythmia should include detailed history and physical examination and a 12- or 15-lead electrocardiogram. In some cases echocardiogram, 24-hour Holter monitoring, exercise stress testing, or other cardiac evaluations may be indicated. Children with a history of cardiac disease or cardiac surgery are particularly at risk for arrhythmias and may experience chest pain in association with their arrhythmias.

Cardiac troponin-I concentrations in dogs with bradyarrhythmias before and after artificial pacing

OBJECTIVES

To quantify cardiac troponin-I (cTnI) concentration in dogs with symptomatic bradyarrhythmias before and after artificial pacing and to correlate cTnI concentration with diagnosis, echocardiographic parameters, serology, and outcome.

ANIMALS, MATERIALS AND METHODS

Medical records from the University of Pennsylvania from 2006 to 2009 were reviewed, and 14 dogs with cTnI assay results before and after pacemaker were identified. The ECG diagnosis included complete atrioventricular block (AVB), sick sinus syndrome, 2nd degree AVB, and atrial standstill. Serology, presence of premature beats, echocardiographic measurements, and pacing modality were recorded.

RESULTS

Mean cTnI concentration was elevated both pre- and post-pacing, and was significantly higher pre-pacing vs. post-pacing. Post-pacing cTnI concentration in 9 of 14 dogs (64%) remained above the reference range. Four dogs yielded high serum titers for Bartonella spp. Four dogs with markedly increased cTnI concentration had progressive left ventricular enlargement and myocardial failure as compared to pre-pacing examination.

CONCLUSIONS

Elevated cTnI concentration suggests that cardiac injury persists after artificial pacing in dogs with bradyarrhythmias. Myocarditis secondary to Bartonella spp. or other causes may be an important cause of AVB in dogs. Prospective studies investigating the correlation of cTnI to potential etiology and development of post-pacing LV dysfunction and outcome are needed.