An one-year old girl presented a persistent tachycardia during a routine visit at the local pediatrician and was immediately transferred to KUNO university hospital. There had been a benign febrile infection 1 week prior to admission. Personal and family history was non-contributory to the tachycardia. Six months before, the previous check at the pediatrician had been uneventful. On admission she had mild signs of heart failure with delayed capillary refill time (3 s) and an enlarged liver. She had a tachycardia with 240 beats/min. Echocardiography showed structural normal anatomy with moderately reduced contractility while tachycardia. Laboratory studies including blood count, inflammatory biomarkers and cardiac troponin were normal but NT-proBNP was significantly elevated (maximum 2,685 pg/ml, lab reference <130 pg/ml).\nThe initial 12-lead electrocardiogram (ECG) showed a regular, sustained small-QRS-complex-tachycardia (mean heart-rate 240 beats/min). The tachycardia demonstrated a 1:1 atrio-ventricular conduction (P-P cycle length 250 ms) with a monomorphic P-wave configuration characterized by a superior axis (P-vector of −60°) and sinus tachycardia was therefore not possible. RP interval was significantly longer than PR—interval (i.e., long-RP-tachycardia) and we thought about a permanent orthodromic supraventricular tachycardia first (such as permanent junctional reciprocating tachycardia) () and gave Adenosine intravenously. This did not stop atrial tachycardia and ruled out a reentry-tachycardia dependent on the AV-node. We therefore hypothesized a focal ectopic atrial tachycardia. Infusion of Flecainide (1 mg/kg/30 min) did not affect the atrial rate or atrioventricular conduction. Synchronized electric cardioversion with 0.5 and 1 J/kg was performed due to signs of hemodynamic instability but this just interrupted the tachycardia for seconds. Medical cardioversion and rate control were attempted starting Amiodarone with a bolus. After 30 min the girl developed a second-degree AV-block (type Wenckebach) with ongoing QRS-amplitude alternans, eventually resulting in a bradycardia with 70 beats/min. Amiodarone infusion was stopped and the AV-block resolved. While persisting EAT, Esmolol infusion was started and slowly increased to a maximum rate of 75 mcg/kg/min. This lowered the atrial tachycardia rate to 160 beats/min without affecting the blood pressure. Ivabradine was started with a dose of 0.25 mg (0.025 mg/kg) every 12 h and increased to 0.5 mg (0.05 mg/kg) per dose on the second day. This led to a persistent heart rate reduction to a physiologic level (80–100 beats/min at rest) with alternating periods of restored sinus rhythm and ectopic atrial rhythm. Subsequent ECG recordings showed sinus rhythms with regular AV conduction and no abnormalities of de- or repolarization (). No adverse effects attributable to Ivabradine were registered. After stabilization Esmolol infusion was discontinued and the beta-blocker therapy was switched to Metoprolol administered orally (1 mg/kg/d). Holter evaluation before discharge (1 week after admission) showed sinus rhythm with short times of ectopic atrial rhythm and a regular diurnal pattern and heart rate.\nIn the follow up visits 2 and 10 weeks later echocardiography showed normal left-ventricular function and dimension. The 12-lead-ECG and Holter evaluation showed alternating ectopic atrial and sinus rhythm with a physiologic diurnal heart rate spectrum and a regular response to physical activity (). Combination of Metoprolol and Ivabradine did not cause bradycardia and no other side effects attributable to medication were noticed.
A 38-year-old European woman with type I diabetes mellitus and corrected hypothyroidism and negative family history of dysrhythmias or cardiomyopathies was first noted to have a persistent asymptomatic tachycardia ∼110–120 b.p.m. during the third trimester of her first pregnancy. The 12-lead electrocardiogram (ECG) at the time confirmed P-wave morphology consistent with a sinus tachycardia with normal intrinsic atrioventricular conduction and narrow QRS complex. Reversible causes were ruled out and the tachycardia was attributed to the pregnant state. After delivery of her first son, the tachycardia persisted postpartum over several months and she was referred to Cardiology for suspected inappropriate sinus tachycardia. Apart from the elevated heart rate the physical exam was normal. A transthoracic echocardiogram (TTE) 8 months after delivery demonstrated a dilated left ventricle (LV) with severely impaired function [ejection fraction (EF) 15%], presence of an apical thrombus and an interatrial shunt. A cardiac magnetic resonance imaging (MRI) confirmed the echocardiographic findings and additionally diagnosed an ischaemic scar in the apex () but coronaries were unobstructed on ECG-gated computed tomography coronary angiogram. A genetic screen within the 100 000 Genomes project did not reveal any abnormalities in the 84 genes associated with dilated cardiomyopathy known at the time. The main differential diagnosis was a late diagnosis of peripartum cardiomyopathy with secondary LV thrombus formation complicated by embolic myocardial infarction, or myocarditis and a paradoxical coronary embolic event facilitated by the interatrial defect. With optimal medical heart failure therapy and Warfarin the left ventricular function fully recovered, the left ventricular thrombus resolved completely, and heart rate normalized within 6 months. A persistent foramen ovale closure was performed after recovery of LV function and thrombus resolution based on the differential diagnosis of paradoxical embolism. Warfarin was ceased. An attempt to wean the heart failure medication resulted in progressive LV dilatation (as documented in a routine follow-up cardiac MRI) within 3 months after stopping her betablocker and angiotensin-converting enzyme-inhibitor (ACEI) and were therefore reinstituted. The patient remained asymptomatic throughout.\nThree years later the patient became pregnant with her second child, requiring suspension of ACEI therapy. Bisoprolol was continued and she was closely monitored with clinical and echo surveillance by the Pregnancy Heart Team. Towards the beginning of the third trimester, the patient noted palpitations and a repeated TTE found a mildly impaired left ventricular EF of 46% (compared to previously 57%) and a heart rate of 120 b.p.m. No overt clinical signs of heart failure were present. The 12-lead ECG () demonstrated a regular organized atrial rhythm with 1:1 conduction to the ventricles with discrete monomorphic P waves separated by isoelectric intervals with upright P waves in the inferior leads, negative in aVL and I, and biphasic negative–positive in V1–V2. The electrocardiographical features were consistent with a left-sided FAT with suspected origin from the superior mitral annulus using the Kistler algorithm. A further up-titration of Bisoprolol to maximum dose failed to control her heart rate, worsened her fatigue, and caused loss of hypoglycaemia awareness.\nGiven the deterioration in LV function in the context of a persistent atrial tachycardia and the previous cardiomyopathy during her first pregnancy, treatment to rate control the arrhythmia was mandated; however, options in this circumstance were limited by the safety profile of commonly used antiarrhythmic drugs. Ivabradine was discussed considering the higher incidence of autonomic FATs during pregnancy and the recent evidence of its efficiency in this particular subset of arrhythmias. In view of the limited available data regarding the teratogenic risk of ivabradine, this option was reviewed with the Pregnancy Heart Team and pharmacists, as well as the patient. It was felt that the benefits would outweigh the risks and ivabradine was started at a dose of 5 mg twice daily. A three-lead 24 h Holter ECG was fitted and recording started parallel to commencing the treatment. The effect was observed ∼6 h after the first dose with a successful reduction of the average heart rate to ∼100 b.p.m. (). Ivabradine was further increased to the target dose of 7.5 mg twice daily. A repeated TTE under improved rate control demonstrated an improved left ventricular function (LV EF 55%).\nThe patient was scheduled for obstetric foetal ultrasound scans at gestation Weeks 28, 32, and 36, which revealed no abnormalities, and had an uncomplicated vaginal delivery of a 3900 g healthy male infant at term. A 12-lead ECG 1 month postpartum showed spontaneous resolution of the atrial tachycardia and confirmed normal sinus rhythm. Ivabradine was stopped and her betablocker continued. The ACEI has been reinstituted after the pregnancy. She has been symptom free since delivery.