The clinical presentation depends on the underlying subtype of arrhythmia [1] [2]:

• Outflow tract arrhythmia (OTA) - Developing on the grounds of aberrant cyclic adenosine monophosphate (cAMP) activity, this type is most frequently encountered in individuals between 20-40 years, with a slight predilection toward female gender [1]. Symptoms seem to be aggravated by emotional stress or exertion, most common being palpitations, dyspnea, chest pain and syncope [1]. Cardiac arrest has been rarely associated with OTA [1].
• Ventricular tachycardia (VT) - Defined as 3 or more ventricular beats at a heart rate of more than 120 beats per minute [3], VT is strongly associated with heart disease (eg. myocardial infarction, cardiomyopathies), while electrolyte abnormalities (hypokalemia or hypomagnesemia) or metabolic changes, including acidosis or hypoxemia, can also induce VT [3]. Monomorphic or polymorphic (the ectopic beat arises from one or multiple foci) and sustained or nonsustained subtypes exist. Nonsustained forms may be asymptomatic, as they are of short duration, but sustained VT is universally symptomatic, manifesting with palpitations, hemodynamic instability, and sudden cardiac death [3], which is not uncommon in severe structural heart disease (SHD).
• Long QT and Brugada syndromes - Two ventricular arrhythmias induced by genetic events present usually in early life (mean onset of symptoms in long QT syndrome is 12 years of age) manifest through syncope, seizures, palpitations, and cardiac arrest [1] [3]. The nocturnal appearance of symptoms is characteristic of Brugada syndrome [3].
• Ventricular fibrillation - Considered as the most severe form of arrhythmia, chaotic ventricular conduction leads to immediate syncope and death within minutes without adequate therapeutic measures [3].

• Falling

  Blood pressure tends to fall, and heart failure follows. Sustained ventricular tachycardia is also dangerous because it can worsen until it becomes ventricular fibrillation —a form of cardiac arrest. [merckmanuals.com]

  The QT interval is markedly prolonged (at least 600ms), with each PVC falling on the preceding T wave ( ‘R on T’ phenomenon). This ECG is extremely high risk for TdP – in fact this patient had a TdP cardiac arrest shortly after this ECG was taken. [lifeinthefastlane.com]

  The QTc interval in men decreases at puberty and then gradually increases as androgen levels fall ; this is also the reason women typically have a longer QT interval than men. [pharmaceutical-journal.com]

  His description is as follows: "The ventricular muscle is thrown into a state of irregular arrhythmic contraction, whilst there is a great fall in the arterial blood pressure, the ventricles become dilated with blood as the rapid quivering movement of [en.m.wikipedia.org]

  Such patients when they experience VT can try vagal maneuvers at home or even try to fall asleep in hopes that the VT will go away on its own. [heartracing.com]

• Multiple Congenital Anomalies

  Patients with 15q24 microdeletion syndrome exhibit distinct dysmorphic features, microcephaly, variable developmental delay, multiples congenital anomalies while individuals with reciprocal 15q24 microduplication syndrome show mild developmental delay [ncbi.nlm.nih.gov]

• Precocious Puberty

  We report the first case of a 10 year-old girl presenting mild developmental delay, psychomotor retardation, epilepsy, ventricular arrhythmia, overweight and idiopathic central precocious puberty. 180K array-CGH analysis identified a 1.38 Mb heterozygous [ncbi.nlm.nih.gov]

• Heart Disease

  A total of 123 consecutive patients confirmed ischemia heart disease with ICD were examined. After device implantation, the occurrence of appropriate ICD therapy was noted. [ncbi.nlm.nih.gov]

  disease, or positive family history. [symptoma.com]

  Inflammatory, rheumatic and valvular heart diseases 11.1 Myocarditis 11.2 Endocarditis 11.3 Rheumatic heart disease. 11.4 Pericarditis 11.5 Cardiac sarcoidosis 11.6 Valvular heart disease 12. [escardio.org]

• Ventricular Bigeminy

  In this paper, we propose a new method for detection and classification of shockable ventricular arrhythmia (VT/VF) and non-shockable ventricular arrhythmia (normal sinus rhythm, ventricular bigeminy, ventricular ectopic beats, and ventricular escape [ncbi.nlm.nih.gov]

  - ventricular bigeminy is the occurrence of a PVC every other beat, trigeminy is every third beat, quadrigeminy every fourth beat. The main point with these types is that the PVC’s are more frequent in these circumstances. [heartpoint.com]

  Example 5 R on T phenomenon: There is sinus rhythm with frequent PVCs in a pattern of ventricular bigeminy. The QT interval is markedly prolonged (at least 600ms), with each PVC falling on the preceding T wave ( ‘R on T’ phenomenon). [lifeinthefastlane.com]

  The term “ventricular bigeminy” refers to alternating normal sinus and premature ventricular complexes. Three or more successive premature ventricular complexes are arbitrarily defined as ventricular tachycardia. [aafp.org]

  bigeminy " PVCs that occur at intervals of 2 normal beats to 1 PVC are termed "PVCs in trigeminy" Three premature ventricular grouped together is termed a "run of PVCs" in general, runs lasting longer than three beats with an increased heart rate are [en.wikipedia.org]

• Irregular Heart Rhythm

  Ventricular Fibrillation (VF) is a rapid, irregular heart rhythm caused by abnormal electrical signals from the ventricles (lower chambers of the heart). Most cardiac arrest patients suffer from ventricular fibrillation (VF). [altabatessummit.org]

  For many people with this condition, irregular heart rhythms are the first and only sign of coronary artery disease. Ventricular fibrillation (VFib) may be confused with atrial fibrillation (AFib). [medicalnewstoday.com]

  AFib is the most common form of serious arrhythmia, or irregular heart rhythm. If you receive an AFib classification and you have not been diagnosed with AFib, you should talk to your doctor. [support.apple.com]

• Palpitations with Skipped Beats

  Common symptoms include the following: Palpitations, feeling "skipped beats" Thumping or fluttering in the chest Sensation of the heart racing In addition, some can experience symptoms that are more generalized, including the following: Feeling faint [emedicinehealth.com]

• Brachydactyly

  The patient had brachydactyly and his second fingers and toes were longer than the others, a finding consistent with PHP. Laboratory tests detected hypomagnesemia, as well as elevated levels of creatine kinase and lactate dehydrogenase. [ncbi.nlm.nih.gov]

• Osteoporosis

  INTRODUCTION: Bisphosphonates, including ibandronate, are used in the prevention and treatment of osteoporosis. [ncbi.nlm.nih.gov]

• Psychomotor Retardation

  We report the first case of a 10 year-old girl presenting mild developmental delay, psychomotor retardation, epilepsy, ventricular arrhythmia, overweight and idiopathic central precocious puberty. 180K array-CGH analysis identified a 1.38 Mb heterozygous [ncbi.nlm.nih.gov]

• Seizure

  Patients usually present with hypocalcemia-induced seizures or tetany, whereas no case of hypocalcemia-induced cardiac arrhythmia in PHP has been described to date. [ncbi.nlm.nih.gov]

  Long QT and Brugada syndromes - Two ventricular arrhythmias induced by genetic events present usually in early life (mean onset of symptoms in long QT syndrome is 12 years of age) manifest through syncope, seizures, palpitations, and cardiac arrest. [symptoma.com]

  Individuals who are being considered for cardiac transplantation and are on a cardiac transplant list History of seizures or epilepsy Cardiac ablation within 3 months prior to screening or planned cardiac ablation during the study Severe renal impairment [clinicaltrials.gov]

  If the ventricular tachycardia persists longer, patients may then manifest a generalized seizure. In both syncope and seizure presentations, the heart eventually catches itself, reverts back to normal sinus rhythm, and the "spell" stops. [sads.org]

  […] disorder should be suspected when the electrocardiogram shows characteristic QT abnormalities, or when there is a family history of long QT syndrome or of an event that raises suspicion of long QT syndrome, such as sudden death, syncope, or ill-defined “seizure [mdedge.com]

• Neglect

  The aim of this study was to review this often-neglected topic, which is of special importance in the CKD population. [Indexed for MEDLINE] Free full text [ncbi.nlm.nih.gov]

Prompt diagnostic workup is mandatory in defining the exact type of arrhythmia, starting with a thorough physical examination and a detailed patient history that could reveal the presence of comorbidities, use of pro-arrhythmogenic drugs, structural heart disease, or positive family history [4]. A 12-lead electrocardiogram (ECG) should be performed immediately in patients who present with symptoms suggestive of arrhythmia, followed by a transthoracic echocardiogram in order to evaluate cardiac structure and exclude structural heart disease as a possible cause [4] [5]. ECG findings may include a widened QRS complex (both prolongation and change in shape), ST elevation and inversion of T waves in the case of ventricular tachycardia and fibrillation, while prolonged QT intervals and coving of the ST-segment are seen in long QT syndrome and Brugada syndrome, respectively [1] [4] [5]. In addition to ECG and echocardiography, laboratory workup should comprise a complete blood count, cardiac markers (troponin, creatine kinase MB, and myoglobin), serum electrolytes (potassium, sodium, magnesium, calcium) and renal function tests, to determine optimal therapy and perform electrolyte correction [3] [4]. If symptoms appear in childhood, genetic testing to confirm mutations characteristic for Brugada or long QT syndromes is necessary [4]. If the cause of arrhythmia remains unresolved, coronary arteriography, exercise stress testing and cardiac magnetic resonance imaging (MRI) have been suggested as additional diagnostic methods [4].

• Wide QRS Complex

  When confronted with a wide-QRS-complex tachycardia it can be difficult to differentiate between a supraventricular tachycardia with aberrancy or ventricular tachycardia. [en.ecgpedia.org]

  Therefore, late premature wide QRS complexes (after the T wave, for example) are most often ventricular ectopic in origin. [ecg.utah.edu]

  A new approach to the differential diagnosis of regular tachycardia with a wide QRS complex. Circulation 1991; 83:1649-59. 21. [slideshare.net]

  QRS complex), or ventricular (wide QRS complex). [msdmanuals.com]

• Staphylococcus Aureus

  A 58-year-old woman with previous mitral and tricuspid valve replacement and permanent pacemaker implantation suffered from recurrent fever and Staphylococcus aureus bacteremia. [ncbi.nlm.nih.gov]

• Ventricular Bigeminy

  In this paper, we propose a new method for detection and classification of shockable ventricular arrhythmia (VT/VF) and non-shockable ventricular arrhythmia (normal sinus rhythm, ventricular bigeminy, ventricular ectopic beats, and ventricular escape [ncbi.nlm.nih.gov]

  - ventricular bigeminy is the occurrence of a PVC every other beat, trigeminy is every third beat, quadrigeminy every fourth beat. The main point with these types is that the PVC’s are more frequent in these circumstances. [heartpoint.com]

  Example 5 R on T phenomenon: There is sinus rhythm with frequent PVCs in a pattern of ventricular bigeminy. The QT interval is markedly prolonged (at least 600ms), with each PVC falling on the preceding T wave ( ‘R on T’ phenomenon). [lifeinthefastlane.com]

  The term “ventricular bigeminy” refers to alternating normal sinus and premature ventricular complexes. Three or more successive premature ventricular complexes are arbitrarily defined as ventricular tachycardia. [aafp.org]

  bigeminy " PVCs that occur at intervals of 2 normal beats to 1 PVC are termed "PVCs in trigeminy" Three premature ventricular grouped together is termed a "run of PVCs" in general, runs lasting longer than three beats with an increased heart rate are [en.wikipedia.org]

• T Wave Alternans

  Catecholamine provoked microvoltage T wave alternans in genotyped long QT syndrome. Pacing & Clinical Electrophysiology. 2003;26(8):1660–7. Google Scholar 104. Nemec J, Hejlik JB, Shen WK, Ackerman MJ. [doi.org]

  Other noninvasive tests, such as T-wave alternans, signal-averaged ECG, and heart rate variability, do not provide diagnostic confirmation, but might be helpful in defining arrhythmia risk in patients with CAD. 17 Electrocardiographic Findings During [revespcardiol.org]

• Electrocardiogram Change

  If the VA occur during or less than 10 seconds after injection and some typical electrocardiogram changes (such as bradycardia, QT interval prolongation, T-wave amplitude, rotation of QRS axis, and PR prolongation) are simultaneously observed before the [revespcardiol.org]

1. Prystowsky EN, Padanilam BJ, Joshi S, Fogel RI. Ventricular Arrhythmias in the Absence of Structural Heart Disease. J Am Coll Cardiol. 2012;59(20):1733-1744.
2. Roberts-Thomson KC1, Lau DH, Sanders P. The diagnosis and management of ventricular arrhythmias. Nat Rev Cardiol. 2011;8(6):311-321.
3. Hebbar AK, Hueston WJ. Management of common arrhythmias: Part II. Ventricular arrhythmias and arrhythmias in special populations. Am Fam Physician. 2002;65(12):2491-2496.
4. Pedersen CT, Kay GN, Kalman J, Borggrefe M, Della-Bella P, Dickfeld T, et al. EHRA/HRS/APHRS expert consensus on ventricular arrhythmias. Europace. 2014;16(9):1257-1283.
5. Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.