Herz 2013 · 38:423–426DOI 10.1007/s00059-012-3711-0Received: 6 June 2012Revised: 11 September 2012Accepted: 3 October 2012Published online: 26 January 2013© Urban & Vogel 2013

M. Sunbul · O. Erdogan · B. MutluDepartment of Cardiology, School of Medicine, Marmara University, Istanbul

Torsade de pointesA rare cause of syncope in severe aortic stenosis

A 79-year-old woman was admitted to our clinic for further evaluation of two syncopal events at rest within the last 2 months. Her physical examination re-vealed a 3/6 late-peaking systolic ejection murmur at the right upper sternal area radiating into her right neck and clavi-cle. Blood pressure and heart rate were 145/75 mmHg and 53 bpm, respectively. She had been using only ramipril 5 mg/day. Surface ECG showed second de-gree Mobitz type 1 atrioventricular block and pronounced U waves in almost all leads. The corrected QT (QTc) interval was 444 ms. Chest X-ray showed bilat-eral pleural effusion. Echocardiography revealed hypokinesis of the anterosep-tal segment, left ventricular hypertro-phy (LVH), ejection fraction 50%, maxi-mal aortic valve velocity 4.74 m/s, mean transaortic pressure gradient 45 mmHg, and aortic valve area 0.8 cm2 (. Fig. 1). Laboratory findings on admission were as follows: blood urea nitrogen 42 mg/dl, creatinine 1.2 mg/dl, sodium 137 mg/dl, potassium 3.5 mg/dl, magnesium 2.3 mg/dl, and calcium 8.8 mg/dl. Clinical and echocardiographic findings were consis-tent with severe aortic stenosis (AS). Be-cause the patient was symptomatic due to syncopal events, aortic valve surgery was tentatively planned.

On the next day after admission, she suddenly developed another syncopal event at rest that was related to a tors-ade de pointes (TdP) episode detect-ed on telemetry recording (. Fig. 2). She was immediately cardioverted with 360 J. Electrolytes on the same day were as follows: sodium 135 mg/dl, potassium 3.2 mg/dl, magnesium 1.5 mg/dl, and cal-

cium 8.5 mg/dl. Depleted levels of mag-nesium and potassium were replaced by intravenous route and temporary pace maker wire was inserted for underlying bradycardia. The pacing rate was set at 80 bpm.

On day 3 after admission coronary angiography demonstrated severe steno-sis of the proximal left anterior descend-ing coronary artery, which was subse-quently dilated with a stent. Although electrolyte levels were normalized, ev-

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Fig. 1 8 a Echocardiographic Doppler measurements of stenosed aortic valve. b Transesophageal short-axis view of stenosed aortic valve (aortic valve area: 0.8 cm2)

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ery time when the pacing rate was low-ered to less than the intrinsic heart rate nonsustained episodes of TdP recurred. ECG taken at that time revealed normal QTc interval and apparent U waves that were always present during all ECG re-cordings.

On day 5 after admission, while the patient was on the list and waiting for aortic valve surgery, she suddenly lost consciousness because of respirato-ry arrest. The monitored rhythm was paced rhythm at that time and no ven-tricular arrhythmia was detected. Al-though cardiopulmonary resuscitation was immediately performed, she unfor-tunately died of electromechanical dis-sociation.

Discussion

Mortality dramatically increases after aortic stenosis becomes symptomatic. The average survival rate is 2–3 years in symptomatic patients without surgical treatment [1]. Survival curves derived from older retrospective studies showed that the interval from the onset of symp-toms to the time of death was approxi-mately 2 years with heart failure, 3 years with syncope, and 5 years with angina [2]. In patients who do not undergo sur-gical intervention, recurrent hospital-izations for angina and decompensated heart failure are frequently encountered [1, 2]. In patients with echocardiograph-ic measures consistent with severe aor-tic stenosis syncope must be presumed to be the result of mechanical obstruc-tion, although other potentially caus-ative conditions such as vasovagal syn-cope or ventricular arrhythmias are gen-erally overlooked and not considered in the differential diagnosis. Syncope dur-ing exertion is most commonly relat-ed to reduced cerebral perfusion when arterial pressure consequently declines with systemic vasodilation in the pres-ence of a fixed cardiac output. Synco-pe has also been attributed to malfunc-tion of the baroreceptor mechanism in severe AS [3]. Although rarely observed, syncope at rest may also be related to ep-isodes of ventricular arrhythmias such as TdP [4]. Similarly, we also suggested that the underlying cause of syncope at

Fig. 2 8 a Rhythm strip showing second degree Mobitz type-1 atrioventricular block and bradycar-dia. Note prominent U waves after the pauses (arrows). b Rhythm strip showing macro T wave alter-nans preceding TdP episode. Note inverted deep T waves (arrows) after the pause and upright T waves (arrow head). c Telemetry recording of TdP and underlying bradycardia when the patient experienced syncope at rest. d Surface ECG demonstrating normal QTc and small U waves after the electrolytes were replaced. e Telemetry recording of nonsustained TdP episodes when the pacing rate was lowered less than the intrinsic heart rate. Note initiation of TdP with typical short–long–short sequence

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rest which was the main complaint of our patient during the last 2 months might have been related to TdP episodes. It is worth of highlighting that ventricular arrhythmias such as TdP should always be considered in the differential diagno-sis of syncope in patients with AS espe-cially when it occurs at rest and is asso-ciated with long QTc interval or U waves [5, 6]. Keeping this possibility in mind, appropriate management of our patient was not so easy. Unfortunately, while considering the best management strate-gy we were faced with some challenging and controversial issues such as not on-ly determining the underlying cause of the TdP and pronounced U waves, but also determining whether aortic valve surgery was absolutely necessary for this symptomatic patient, whose main com-plaint was syncope at rest and probably arrhythmogenic, and whether this pa-tient needed an intracardiac defibrillator (ICD) or pacemaker regardless of aortic valve surgery.

The left ventricle becomes hypertro-phied in an attempt to overcome the pres-sure load caused by AS. Patient with sig-nificant AS and LVH have increased QT dispersion that might be associated with susceptibility to ventricular arrhythmias or sudden cardiac death [7]. Local isch-emia of the hypertrophied ventricle and increased anisotropy as well as stretching of myocardial fibers could all be respon-sible for ventricular arrhythmias in ad-dition to increased QT dispersion in pa-tients with LVH. Although the baseline QTc was normal in our case, underlying QT dispersion, U waves and bradycardia in addition to LVH may be implicated as predisposing factors for TdP. The funda-mental feature of TdP is its provocation by pause-related augmentation of the re-polarizing TU wave [8]. Underlying isch-emia created by severe coronary stenosis that was alleviated by stenting might be implicated as another contributory factor for TdP in our case.

Although the combination of QT pro-longing drugs and electrolyte disorders are more often a cause of TdP, it can al-so be caused alone by hypokalemia, hy-pomagnesemia, and rarely hypocalce-mia [9]. Although electrolyte levels on admission were within the normal rang-

es, depleted levels of magnesium and po-tassium were detected on the day of syn-cope for which we could not provide a plausible explanation such as diuret-ic related electrolyte disorder. Electro-lyte disorder might be considered one of the predisposing factors for TdP in our case. However, subsequent episodes of non-sustained TdP occurred after elec-trolytes were replaced and their plas-ma levels were within the normal rang-es. Electrolyte disorders can alter cardi-ac ionic current kinetics and depending on the changes can promote ventricu-lar arrhythmias. Potassium is the most abundant intracellular cation and hypo-kalemia is the most common electrolyte disorder encountered in clinical practice [9]. Hypomagnesemia may be more ar-rhythmogenic when combined with hy-pokalemia and bradycardia. The admin-istration of intravenous magnesium sul-fate to patients with prolonged QT inter-val and TdP, whether the initial magne-sium level is normal or low may suppress TdP [9]. Conditions such as LVH, isch-emia, bradycardia, hypokalaemia, and hypomagnesemia can be responsible for prominent U wave which is strongly rate dependent and much pronounced dur-ing bradycardia. Hypokalemia is also associated with flattening of the T wave and prominent U waves [10]. Prominent and alternating U waves were associat-ed with ventricular irritability and de-scribed in patients with low serum mag-nesium levels. Prolongation of the QT interval, changes in TU wave morphol-ogy and subsequent TdP results in ab-normal function of ion channels and re-lated proteins involved in the repolar-ization process of ventricular myocytes [10]. Although we replaced magnesium and potassium to normal levels, TdP ep-isodes recurred. Normalizing electrolyte levels in this particular patient did not suppress subsequent TdP episodes be-cause there were other underlying pre-disposing factors such as LVH, U waves, QT dispersion, and bradycardia which could be implicated for recurrence of TdP. Whether TdP will recur after dis-charge and place the patient at risk of sudden cardiac death regardless of aor-tic valve surgery remains speculative. Hence, arrhythmogenic death seems to

be much more speculative cause of death than mechanical obstruction in our pa-tient. Accordingly, we think that im-planting an ICD would have been an ap-propriate option for treating her synco-pal events and improving prognosis.

Unfortunately, the cause of death is not clear in this case report. Although we intended to perform autopsy, this was not allowed by the patient’s family. There-fore, we can only speculate that a major pulmonary emboli might have been the most likely cause of hemodynamic col-lapse and death. Underlying stent throm-bosis and acute coronary event should al-

Abstract · Zusammenfassung

Herz 2013 · 38:423–426DOI 10.1007/s00059-012-3711-0© Urban & Vogel 2013

M. Sunbul · O. Erdogan · B. Mutlu

Torsade de pointes. A rare cause of syncope in severe aortic stenosis

AbstractThe evaluation of syncope in severe aor-tic stenosis usually requires intense work-up. Mechanical obstruction should not always be implicated as the underlying cause of syn-cope. Syncope at rest may be rarely associ-ated with ventricular arrhythmias. We pres-ent a patient with severe aortic stenosis who experienced syncopal events due to torsade de pointes.

KeywordsAortic stenosis · Syncope · Sudden death · Therapy · Arrhythmia

Torsade de pointes. Seltene Ursache für eine Synkopen bei hochgradiger Aortenstenose

ZusammenfassungDie Evaluierung einer Synkope bei schwe-rer Aortenstenose erfordert in der Regel eine umfangreiche Diagnostik. Nicht immer sollte eine mechanische Obstruktion als zugrunde-liegende Ursache impliziert werden. Selten kann eine Synkope in Ruhe mit ventrikulären Arrhythmien assoziiert sein. Vor ge stellt wird eine Patientin mit hochgradiger Aortenste-nose, die aufgrund von Torsade-de-pointes-Rhythmusstörungen synkopale Er eig nisse erlitt.

SchlüsselwörterAortenstenose · Synkope · Plötzlicher Tod · Therapie · Arrhythmie

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so be implicated as the cause of sudden death because pacemaker rhythm might have potentially obscured any acute ST segment changes. However, the patient did not describe any prior symptom such as angina and there was no ventricular arrhythmia detected on telemetry mon-itoring. She suddenly developed sudden respiratory arrest during which the mon-itor recorded stable paced QRS rhythm, but there were no pulse or measurable blood pressure.

Conclusion

We would like to emphasize that not all syncopal events, especially when they occur at rest in a patient with severe AS, are related to mechanical obstruc-tion and amenable with aortic valve surgery. Ventricular arrhythmias such as TdP might be an overlooked cause for syncope in patients with severe AS. How precisely should clinicians man-age and elucidate the cause of syncope in such patient, remains a challenging issue. Therefore, every effort should be undertaken to determine the underly-ing mechanism of syncope and appro-priately plan the therapeutic strategy while managing a patient with severe AS and syncope at rest. 

Corresponding address

Prof. O. ErdoganDepartment of Cardiology,  School of Medicine, Marmara UniversityIstanbulTurkeyokanerdogan@yahoo.com

Conflict of interest.  On behalf of all authors, the corresponding author states that there are no con-flicts of interest.

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