HISTORY, CURRENT ILLNESS AND PHYSICAL EXAMINATION

PERSONAL HISTORY
72-year-old woman, retired. Lives alone with good family support. Active life.
No known drug allergies.
No smoker or drinker.
No known hypertension (HTN), diabetes mellitus (DM) or dyslipidaemia.
No known heart disease or bronchopathy.
No surgical interventions of interest.
No chronic treatments.

PRESENT ILLNESS
72-year-old woman brought to the emergency department by the emergency services due to poor general condition and unspecific abdominal pain of several days' evolution. On arrival, poor clinical and haemodynamic condition, with blood pressure around 80/40 mmHg and heart rate (HR) of 190 bpm, with peripheral hypoperfusion and lividity in all four extremities together with low level of consciousness. Given the poor clinical condition, orotracheal intubation was performed and admission to the intensive care unit (ICU) was decided.

PHYSICAL EXAMINATION
Blood pressure (BP) 85/42 mmHg, HR 190 bpm, oxygen saturation (SatO2) not assessable due to hypoperfusion, afebrile.
Poor general condition, low level of consciousness and skin coldness and peripheral hypoperfusion.
No jugular ingurgitation.
Cardiac auscultation: rhythmic heart sounds at 190x ́ without murmurs.
Pulmonary auscultation: preserved vesicular murmur, without added pathological sounds.
Abdomen: abdominal distension, with preserved hydro-aerial sounds. Hepatomegaly of 2 traverses.
Upper extremities: poor distal perfusion, no palpable pulses. Lividity in both extremities.
Upper extremities: poor distal perfusion, no palpable pulses. No oedema or signs of deep vein thrombosis (DVT). Lividity in both extremities.

COMPLEMENTARY TESTS
Laboratory tests on admission to the ICU:
Haemogram: leucocytes 16800/μL (80% polymorphonuclear), Hb 12.4 g/dl, platelets 335,000/μl.
Coagulation: INR 1.8, aPTT 28.3 sec.
Biochemistry: creatinine 1.32 mg/dl, urea 87 mg/dl, sodium 127 mEq/l, potassium 3.7 mEq/l, bilirubin 1 mg/dl, aspartate aminotransferase 696 U/l, alanine aminotransferase 629 U/l, gamma-glutamyl-transpeptidase 162 U/l, amylase 97 mg/dl, troponin T 39 ng/l, C-reactive protein 13 mg/dl, procalcitonin 0.15 ng/ml.
TSH normal.
Electrocardiogram (ECG) on admission: regular tachycardia at 200 bpm without visualisation of p waves, normal axis, narrow QRS, ST rectification on the inferolateral side.
ECG after cardioversion: atrial fibrillation (AF) at 90 bpm with isolated ventricular extrasystoles, normal axis, narrow QRS, inferolateral ST rectification, normal QT.
ICU ECG: regular tachycardia at 140 bpm, inferior axis, wide QRS with morphology of complete right bundle branch block (RBBB) and secondary repolarisation abnormalities.
ECG after transient pacemaker (PM) implantation: atrial rhythm at 80 bpm stimulated by pacemaker with negative p waves in inferior face with short PR (100 ms), normal axis, QRS 100 ms (widened with respect to baseline) with evident positive pre-excitation in V2-V5.
ECG at discharge: RS at 60 bpm, normal axis, PR 120 ms, narrow QRS without pre-excitation, QT 400 ms, no signs of acute ischaemia or repolarisation disturbance.
Portable chest X-ray on admission: normal cardiothoracic index. Congestive hilar with slight vascular redistribution. Free costophrenic sinuses. No condensation images.
CT scan of the abdomen with intravenous contrast on admission: bilateral pleural effusion.
Hepatomegaly. Marked reduction in the calibre of the main branches of the abdominal aorta, especially the distal branches of the superior mesenteric, which could justify hypoperfusion of the tributary territory of the same.
Echocardioscopy on admission (performed in regular TQ at 190 x ́): LV of normal size with marked global hypocontractility and severe systolic dysfunction. RV of normal size and function. Mitral insufficiency that appears mild-moderate (difficult to quantify in TQ at 190x ́), the rest without relevant incidences.
Transthoracic echocardiography prior to discharge: non-dilated left ventricle (LV) with slight concentric hypertrophy. No segmental contractility disorders. Diastolic dysfunction grade II. LVEF 65% by Simpson BP. Right ventricle (RV) of normal size and function. Anatomically normal mitral valve with central insufficiency jet reaching the roof of the left atrium (LA) but with protosystolic predominance, which we classify as mild-moderate. The rest of the valves were normal with no pathological flows.
Inferior vena cava (IVC) not dilated and with adequate inspiratory collapse.

CLINICAL EVOLUTION
The patient was admitted to the ICU in a situation of shock of uncertain origin, in MV and requiring noradrenaline to maintain blood pressure. Given the abdominal symptoms reported by the family prior to admission, it was decided to complete studies with an emergent CT scan of the abdomen, which showed a reduction in the calibre of the main branches of the abdominal aorta with possible hypoperfusion of its tributary territory, so an emergent exploratory laparotomy was performed, which showed no pathological findings.
Back in the ICU, echocardioscopy was performed with the finding of marked global hypocontractility and severe systolic dysfunction. Given the situation of shock with vasopressor amines and the persistence of rhythmic tachycardia with narrow QRS at 200 bpm, it was decided to perform electrical cardioversion (ECV) at 200J on suspicion of persistent supraventricular tachycardia, which was effective but the patient immediately presented AF with controlled ventricular rate. The condition was labelled as cardiogenic shock and iv dobutamine perfusion was added, but the patient had a torpid evolution with significant haemodynamic instability despite noradrenaline and dobutamine, progressing to multi-organ failure (oligoanuric liver and kidney failure requiring haemofiltration).
From the arrhythmic point of view, the patient presented several subsequent recurrences of narrow QRS tachycardia at 200 bpm, in addition to frequent bouts of wide QRS rhythmic tachycardia at 140 bpm with HRBBB morphology and occasional mildly irregular lower axis. The patient was initially diagnosed as ventricular tachycardia, so amiodarone perfusion was started and discontinued after 24 hours due to QTc prolongation up to 610 ms. Given the persistence of this wide QRS tachycardia, which did not subside with procainamide, esmolol and multiple CVE, a transient pacemaker was implanted for over-stimulation. Incidentally, the pacemaker lead was placed in the coronary sinus, and the post-implantation ECG showed atrial capture with short PR and delta wave suggestive of ventricular pre-excitation.
During this period, the patient remained in cardiogenic shock, with persistent multi-organ failure and the need for vasoactive amines. Control echocardiograms showed a slight improvement in ventricular function, but given the persistence of arrhythmic events despite medical treatment and stimulation, and with the suspicion of a possible accessory pathway, it was decided to perform an electrophysiological study (EPS).
In the EPS, the clinical wide QRS tachycardia was induced, finding atrial flutter with 2:1 AV conduction and wide QRS with BCRDHH morphology and short HV compatible with pre-excited 2:1 flutter. In addition, bouts of orthodromic tachycardia (regular with narrow QRS) are induced, equal to the clinic with eccentric atrial activation sequence in the coronary sinus with earlier atriogram in S2-S3, which frequently degenerate into pre-excited AF (irregular with irregular wide QRS). Effective ablation was performed on the left posterolateral accessory pathway with disappearance of the pre-excitation 2 seconds after application, and the absence of retrograde conduction through the pathway was verified.
After the procedure, the patient returned to the ICU, where she remained in alternating atrial fibrillation and atrial flutter (narrow QRS), without pre-excitation and with ventricular response controlled with digoxin. During the following days, he showed good haemodynamic and clinical evolution, allowing extubation, withdrawal of perfusions and transfer to the cardiology ward after stabilisation, where he persisted at all times with controlled HR and alternating AF and flutter monitoring without presenting new bouts of tachycardia. After 15 days of hospitalisation, discharge was decided, with prior performance of a new echocardiography, which showed preserved biventricular systolic function without segmental alterations of contractility, mild-moderate functional mitral insufficiency and diastolic dysfunction.

DIAGNOSIS
Wolff-Parkinson-White syndrome via left posterolateral approach with orthodromic tachycardia, pre-excited atrial fibrillation and flutter.
Tachycardiomyopathy secondary to the above with severe systolic dysfunction recovered after accessory pathway ablation.
Cardiogenic shock with multi-organ failure secondary to previous diagnoses.
