Keywords

Syncope, vasovagal, posture, cardiac causes, atrioventricular block

Dizziness or syncope may occur in any human being due to inadequate perfusion of brain due to various reasons, commonest among it is reflex (vasovagal syncope). This is neurally-mediated during emotional stress, orthostatic stress, situational or carotid sinus hypersensitivity. Other causes are numerous and approximately 40% population is affected once during lifetime (more common in young female), but only few need medical intervention. Syncope/dizziness due to cardiac causes increases with age and is found in 2-3% population over age of 80 years.¹

A careful history about posture, situation, recent medication or history of comorbidity may help in arriving at diagnosis and further management. Cardiac causes like sick sinus, atrioventricular (AV) block, PSVT, VT, long QT syndrome, malfunctioning pacemakers or implantable cardioverter defibrillator (ICD), drugs may lead to syncope/dizziness. But AV block with change in posture from supine to sitting/erect posture without any of the above-mentioned cause is very uncommon;² we encountered such a case in an elderly male and hence this case report.

Case Report

An elderly male aged about 60 years suddenly felt dizziness and sense of palpitation (missing heart beats) during normal activity. Patient had no history of any comorbid conditions like diabetes, hypertension, coronary artery disease (CAD), drug intake or any other major illness in recent past but had a history of occasional episodes of palpitation for few seconds for past 30 years and repeated.

Holter monitoring had shown only few ventricular premature contraction in 2-3 reports, which was insignificant. Due to giddiness and unable to do normal activity, was taken to tertiary care hospital for needful. On examination, in supine posture heart rate was 78/min regular, blood pressure was 140/86 mmHg, respiratory rate 18/min was kept for observation in cardiac care unit.

All other investigations like complete blood count (CBC), liver function tests (LFT), renal function tests (RFT), chest X-ray, blood sugar level, electrolyte, troponin test and cardiac markers were within normal limits. ECG was normal in supine position but whenever patient assumed sitting position felt giddiness and irregular heart beat. So, ECG was recorded on 3 (Three) occasions at time intervals in supine as well as sitting posture, which showed 2:1 heart block (Figs. 1 and 2); on each occasion with assuming sitting posture. As the patient was symptomatic on assuming sitting posture, a permanent pacemaker device was implanted, that solved the problem.

Discussion

Transient loss of consciousness or dizziness is a common symptom in human due to transient fall in cerebral perfusion. Hypotension i.e., a fall in blood pressure of 20 mmHg systolic and 10 mmHg diastolic is acceptable with change in posture from supine to upright position but any fall more than that may be due to medications or failure of autonomic reflex with resulting pooling of blood in dependent part.

Most of the syncope is reflex mediated (depressor reflex) arising in heart, first described by Bezold, is compensated through activation of autonomic nervous system by vasoconstriction and increase in heart rate. Studies suggests that cardiac C-fibers are responsible for slowing heart rate and vasodilatation leading to pooling of blood in dependent part, carotid sinus hyperactivity, parasympathetic activation, organic heart disorders, rhythm abnormality are other leading cause of syncope.³

Paroxysmal heart block by act of sitting up in bed or assuming upright posture with severe symptoms like syncope and fainting without change in blood pressure has been reported by Klein et al in two of their cases, relieved by permanent pacemaker implant.⁴ In a similar case report, Kartikeyan et al⁵ reported reflex syncope in a 52 years lady with normal AV conduction in supine position but advanced AV block in upright posture, necessitating permanent pacemaker implant.

Such cases are encountered infrequently and literature reports only few cases of heart block with change of posture, as with this case. Because of rare occurrence we are reporting this case.

References

1. Michele B. Diagnosis and treatment of syncope. Heart. 2007;93:130-5.
2. Schwela H, Oltmanns G. Postural induced heart block. Am Heart J. 1987;114:1532-4.
3. Mark AL. Clinical implication of inhibitory reflexes originating in heart. J Am Coll Cardiol. 1983;1(1):90-102.
4. Klein HO, Di Segni E, Kaplinsky E. Paroxysmal heart block triggered by sitting up: a usually undetected cause of cerebral ischemia. Heart Lung. 1988;17(6 Pt 1):648-50.
5. Kartikeyan G, Muthukumar D, Arvind A. Reflex syncope manifesting as orthostatic complete heart block. J Assoc Physicians India.2013;61(11):853-5.