Background
Mortality between stage I and II palliation for hypoplastic left heart syndrome (HLHS) has been associated with arrhythmias. The stage-related proportion, associations, and clinical impact of arrhythmias in patients with HLHS have not been evaluated. Also, arrhythmia subtypes have not been described in this patient group.
Methods
We performed a retrospective analysis of all patients at Duke University Medical Center who received one or more palliative stages for hypoplastic left heart syndrome from September 2000 to October 2008.
Results
Overall, 49/86 (57%) patients had 63 arrhythmias. The majority of arrhythmias occurred between stage I and II with 44/86 (51%) patients manifesting a new arrhythmia. Arrhythmias occurring in this interval tended to be associated with a higher mortality compared to arrhythmias occurring after stage II, OR = 3.2 [95%CI 0.84, 12.0] (p=0.09). Overall, mortality was similar in patients with and without arrhythmias (p=0.99). Supraventricular tachycardia was the most common arrhythmia (16/63; 25%) but persistent bradycardias (sinus node dysfunction or high grade atrioventricular block) had the worst clinical outcome with 73% mortality (8/11). There was no association between arrhythmia occurrence and degree of tricuspid regurgitation, left ventricular hypertension, genetic syndrome, type of stage I operation, or need for extracorporeal membrane oxygenation (ECMO).
Conclusions
A large proportion of patients with HLHS experience serious arrhythmias requiring therapy, especially between stages I and II. Persistent bradycardia following stage I is associated with a high mortality rate. Considering all arrhythmia patients, overall mortality was not different compared to the arrhythmia free group.
Cardiac manifestations in multisystem inflammatory syndrome in children (MIS-C) can include coronary artery aneurysms, left ventricular systolic dysfunction, and electrocardiographic disturbances. We report the clinical course of three children with MIS-C while focusing on the unique considerations for managing atrioventricular conduction abnormalities. All initially had normal electrocardiograms but developed bradycardia followed by either PR prolongation or QTc elongation. Two had mild left ventricular ejection fraction dysfunction prior to developing third-degree heart block and/or a junctional escape rhythm; one had moderate left ventricular systolic dysfunction that normalized before developing a prolonged QTc. On average, our patients presented to the hospital 4 days after onset of illness. Common presenting symptoms included fevers, abdominal pain, nausea, and vomiting. Inflammatory and coagulation factors were their highest early on, and troponin peaked the highest within the first two days; meanwhile, peak brain-natriuretic peptide occurred at hospital days 3-4. The patient’s lowest left ventricular ejection fraction occurred at days 5-6 of illness. Initial electrocardiograms were benign with PR intervals below 200 milliseconds (ms); however, collectively the length of time from initial symptom presentation till when electrocardiographic abnormalities began was approximately days 8-9. When comparing the timing of electrocardiogram changes with trends in c-reactive protein and brain-natriuretic peptide, it appeared that the PR and QTc elongation patterns occurred after the initial hyperinflammatory response. This goes in line with the proposed mechanism that such conduction abnormalities occur secondary to inflammation and edema of the conduction tissue as part of a widespread global myocardial injury process. Based on this syndrome being a hyperinflammatory response likely affecting conduction tissue, our group was treated with different regimens of intravenous immunoglobulin, steroids, anakinra, and/or tocilizumab. These medications were successful in treating third-degree heart block, prolonged QTc, and a junctional ectopic rhythm.
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