THE ELECTROCARDIOGRAM OF THE STOKES-ADAMS ATTACK

Pathophysiology of syncope: current concepts and their development

Syncope is a symptom in which transient loss of consciousness occurs as a consequence of a self-limited, spontaneously terminating period of cerebral hypoperfusion. Many circulatory disturbances (e.g. brady- or tachyarrhythmias, reflex cardioinhibition-vasodepression-hypotension) may trigger a syncope or near-syncope episode, and identifying the cause(s) is often challenging. Some syncope may involve multiple etiologies operating in concert, whereas in other cases multiple syncope events may be due to various differing causes at different times. In this communication, we address the current understanding of the principal contributors to syncope pathophysiology including examination of the manner in which concepts evolved, an overview of factors that constitute consciousness and loss of consciousness, and aspects of neurovascular control and communication that are impacted by cerebral hypoperfusion leading to syncope. Emphasis focuses on 1) current understanding of the way transient systemic hypotension impacts brain blood flow and brain function; 2) the complexity and temporal sequence of vascular, humoral, and cardiac factors that may accompany the most common causes of syncope; 3) the range of circumstances and disease states that may lead to syncope; and 4) clinical features associated with syncope and in particular the reflex syncope syndromes.

Ventricular standstill disguised as epilepsy: A case report on Stokes-Adams attacks

Background

Stokes-Adams attacks presenting as convulsions may be difficult to distinguish from epilepsy. Stokes-Adams Syndrome is a transient abrupt collapse into unconsciousness due to a sudden but pronounced decrease in cardiac output caused by change in heart rate and rhythm, resulting in syncope.

Case presentation

We report a patient who presented with multiple convulsive episodes managed as epilepsy, until she was found to have paroxysmal total atrioventricular block. Previously, she had been treated with anti-seizure medications without relief. Ventricular standstill was seen on cardiac monitoring and the convulsive episodes were determined as Stokes-Adams attacks. She underwent percutaneous coronary intervention and has been free of convulsive episodes since.

Conclusion

Awareness of distinction between seizures/epilepsy and convulsive syncope is important and may be life-saving. A good clinical history as well as simple non-invasive tests such as electroencephalogram and electrocardiogram are important in establishing correct diagnosis.

History and evolution of pacing and devices

Cardiac implanted electronic devices are commonplace in the modern practice of cardiology. This article reviews the history of the development of these technologies, with particular reference to the role played by UK physicians and members of the British Cardiovascular Society. Key breakthroughs in the treatment of heart block, ventricular arrhythmia and heart failure are presented in their historical and contemporary context so that the reader might look back on the incredible progress and achievements of the last 100 years and also look forward to what may be achieved in the coming decades.

Incidental Findings of Asystole in a Patient With Complaints of Near Syncope: A Case Report on Paroxysmal Ventricular Standstill

Paroxysmal ventricular standstill (PVS) is an unusual cardiac phenomenon in which the heart experiences episodes of absent ventricular activity despite normal atrial functioning, often leading to cardiac arrest and syncope. In this case, we report the hospital stay of a 70-year-old male who was admitted to the hospital following an episode of near syncope at home. On admission, the patient’s initial electrocardiogram (ECG) showed sinus rhythm at 60 beats per minute without atrioventricular (AV) block. However, as orthostatic vitals were obtained, the patient became lightheaded for several seconds upon standing, which was noted to correspond with a nine second episode of asystole on telemetry and spontaneous return to sinus bradycardia afterward. Cardiology was immediately consulted and confirmed the diagnosis of paroxysmal ventricular standstill (PVS). Given continued episodes of PVS, the patient underwent successful urgent dual-chamber pacemaker placement, following which he became asymptomatic with resolution of bradycardia. Given the high mortality risk associated with PVS, this condition is an important differential to consider in any patient presenting with syncope or near syncope of unclear etiology.

Paroxysmal Ventricular Standstill: A Rare Cardiac Manifestation of Syncope

Patient: Male, 40-year-old

Final Diagnosis: Ventricular standstill

Symptoms: Seizure-like activity

Medication: —

Clinical Procedure: —

Specialty: Cardiology

Paroxysmal ventricular tachycardia; a study of 107 cases

A review is presented of 107 cases of paroxysmal ventricular tachycardia. In the majority it was associated with acute coronary thrombosis or coronary sclerosis, in some with rheumatic valvular disease, and in others with no organic heart disease. It is generally critical and demands careful attention. Occasional cases are overlooked because only one heart sound is present for each cardiac cycle and the heart rate is misjudged to be one-half the actual rate. The outlook often is serious if the condition is not effectively treated. Therapy generally is successful in controlling the arrhythmia. The most valuable drug is quinidine. Other medications are magnesium sulfate, atropine, potassium salts, and possibly morphine.

Congenital aneurysmal defect of the membranous portion of the ventricular septum associated with heart block, ventricular flutter, Adams-Stokes syndrome and death

A case of congenital aneurysmal defect of the ventricular septum is reported which appears to be unique in that this lesion was the only significant finding at autopsy. The patient had evidence of auriculoventricular block for a period of 26 years, at first partial and then complete. She succumbed at the age of 47 to a series of Adams-Stokes attacks which were demonstrated to be set off by paroxysmal ventricular flutter followed by ventricular tachycardia and ventricular standstill. Pertinent literature is briefly reviewed.

Increased propensity of women to develop torsades de pointes during complete heart block

INTRODUCTION

To determine whether an increased female gender susceptibility to torsades de pointes (TdP) may exist in a clinical model of bradycardia-induced long QT syndrome, we investigated reported cases of TdP associated with acquired complete heart block.

METHODS AND RESULTS

Seventy-two cases reported in the medical literature dating from 1941 through 1993 were identified, all describing TdP or "transient ventricular tachycardia/fibrillation" (to include those cases reported prior to the use of TdP terminology) in the setting of acquired complete heart block unassociated with QT prolonging drugs. Expected female prevalence in complete heart block was estimated at 52%, based on projections derived from 206,016 hospital discharges in the National Inpatient Profile (Commission on Professional and Hospital Activities, Ann Arbor, MI), over the years 1985 through 1992. During complete heart block, mean heart rate was 37 beats/min in both sexes (combined n = 43), and absolute QT interval ranged from 0.52 to 0.88 seconds, with a mean of 0.68 seconds (n = 25). Female prevalence among patients with TdP during complete heart block was greater than expected: 72% for all studied cases (P < 0.001); 70% (P < 0.04) and 74% (P < 0.02) among those reported prior to (n = 35) and during or after (n = 37) 1980, respectively; 73% (P < 0.03) among those with documented normokalemia (n = 26); and 68% (P = 0.2) among those with a prolonged QT interval and known polymorphic VT (i.e., unequivocal TdP; n = 25).

CONCLUSION

Despite inherent limitations of this retrospective study, the data are consistent in suggesting a greater than expected female prevalence among patients with TdP related to complete heart block. This finding lends support to a broadening concept of increased susceptibility of women to the development of TdP in various settings of QT prolongation.

Ventricular tachyarrhythmias in the long QT syndromes

Marked prolongation of the electrocardiographic QT interval often is associated with a distinctive form of ventricular tachycardia characterized by the gradual oscillation around the baseline of the peaks of successive QRS complexes. This was named torsades de pointes, or "twisting of the points." This form of ventricular tachycardia tends to be rapid and self-terminating and often occurs in clusters, leading afflicted patients to present with recurrent dizziness and syncope. Ventricular fibrillation and sudden death are common.

Exercise-induced ventricular ectopy in children and young adults with complete heart block

Twenty-five children and young adults with complete heart block and 50 normal control subjects were maximally exercised on a treadmill and their electrocardiograms were analyzed for the presence and degree of ventricular ectopy activity. Sixty-eight % (17 of 25) of the heart block patients and significant ventricular ectopy (frequent unifocal ectopy or worse) on exercise compared to 2% (one of 50) of the controls (p = less than 0.01). In the patients with block there was a significant trend toward more frequent and more severe ectopy with increasing age (p = less than 0.05) independent of heart rate. More severe ventricular ectopy was also seen in those patients with QRS prolongation (p = less than 0.05). No significant differences were found between the 14 patients with isolated "congenital" heart block, the seven with associated defects, and the four with surgically acquired block. We believe that severe ventricular ectopy is common at exercise in patients with complete heart block and they may have an increased risk for sudden death.

Reflex anoxic seizures ('white breath-holding'): nonepileptic vagal attacks

From clinical history 58 children were diagnosed as having reflex anoxic seizures secondary to provoked cardioinhibition (also known as white breath-holding attacks). Before referral, these seizures were commonly misdiagnosed as epileptic either because the provocation was ignored, not recognised, or was a febrile illness, or because there was no crying, no obvious breath-holding, little cyanosis, and often no pallor to suggest syncope and cerebral ischaemia. The duration of cardiac asystole after ocular compression was measured in these children and in 60 additional children with other paroxysmal disorders. In 45 (78%) of the 58 with reflex anoxic seizures asystole was 2 seconds or over, and in 32 (55%) it was 4 seconds or greater, an abnormal response. Review of the literature supports the concept that these seizures result from vagal-mediated reflex cardiac arrest which can if necessary be prevented by atropine. The simple name 'vagal attack' is proposed. Ocular compression under EEG and ECG control supports the clinical diagnosis if asystole and/or an anoxic seizure is induced; the procedure described is safe and should be routine in seizure or syncope evaluation, when a meticulous history still leaves room for doubt.

Comparative effects of overdrive on sinus and subsidiary pacemaker function

Recent evidence has suggested a difference in response to overdrive pacing dependent on the location of the pacemaker within the A-V conduction system. To test this hypothesis, the effects of overdrive pacing were evaluated in five anesthetized dogs with experimentally induced A-V block and in seven patients with advanced A-V block. In the animals, sinoatrial node recovery times were studied over wide ranges of rates (130 to 210 beats per minute) and durations (30 to 180 seconds) of atrial pacing. All sinus node recovery times were less than 600 msec. with a mean maximum pause of 0.540+/-0.043 seconds (M.+/-S.E.M.). In contrast, after ventricular pacing (rates 90 to 150 beats per minute; durations 30 to 180 seconds), subsidiary pacemaker recovery times were significantly greater (p less than 0.025) with a mean maximum recovery time of 28.4+/-8.3 seconds. In the seven patients studied, all sinus node recovery times were less than 1,400 msecs. with a mean maximum pause of 0.954+/-0.051 seconds. As seen with the experimental animals, a significantly longer (p less than 0.025 mean maximum subsidiary pacemaker recovery time of 3.55+/-0.92 seconds was observed. The present studies in both experimental animals and in man without evidence of sinus node dysfunction showed that sinus node recovery time was independent of both rate and duration of atrial overdrive pacing. In contrast, subsidiary pacemaker recovery time was correlated with both rate and duration of ventricular overdrive pacing. In both experimental protocols, subsidiary pacemaker recovery time was shown to exceed sinus node recovery time at all rates and at all durations of pacing. Postrecovery sinus node acceleration was consistently observed after atrial overdrive pacing. In contrast, postrecovery subsidiary pacemaker "depression" characterized ventricular overdrive pacing. It is concluded that subsidiary pacemakers are significantly more susceptible to overdrive suppression than the sinoatrial node, a feature of substantial clinical significance.

The tachycardia-bradycardia syndrome

The tachycardia-bradycardia syndrome (paroxysmal atrial fibrillation, flutter, or tachycardia followed by sinoatrial block or sinus arrest resulting in Stokes-Adams attacks) is an important clinical entity that requires familiarity by the clinician. Pathologic studies and physiologic mechanisms as revealed in the electrocardiogram indicate multiple disturbances in the conduction system of the heart (sinus node, atria, and atrioventricular junctional tissues). The electrocardiogram establishes the diagnosis. Pacemaker implantation with supplementary drugs has provided a satisfactory means of therapy. With proper treatment the prognosis of patients with the tachycardia-bradycardia syndrome has improved to the extent that the primary determinant of mortality is no longer the arrhythmia, but the underlying cardiac and/or systemic pathology.

Complete heart block. Studies of atrial and ventricular pacemaker site and function

Atrial and ventricular pacemaker function was studied in 20 patients with idiopathic chronic complete heart block using the rate response to an intravenous bolus dose of isoprenaline (5 mug/70 kg bodyweight). Pacemaker responses were compared with those of 16 normal control subjects. None of the patients was having syncopal attacks at the time of admission and they were therefore selected in that none required immediate pacing. Ten of the patients had His bundle electrograms; all were shown to have a pre-His type of atrioventricular block. Two major groups emerge from the responses to isoprenaline. (a) High risk group: 11 of the 14 patients with reduced ventricular pacemaker responses had frequent syncopal attacks; 8 of the patients with Adams-Stokes syncope had a bundle-branch block pattern, while 3 had a narrow QRS. These patients require pacing. (b) Low risk group: a low risk asymptomatic group (5 patients) was identified with atrial and ventricular responses to isoprenaline within normal range. One of these patients had a bundle-branch block pattern, while 4 had a narrow QRS. These patients might be managed without pacing. The atrial response to isoprenaline was reduced in 12 of the 20 cases, 10 of whom also had reduced ventricular responses. All 9 patients with bundle-branch block had reduced ventricular responses, while 7 had reduced atrial responses. This evidence indicates that cardiac conducting tissue pathophysiology is widespread in complete heart bolck. The present work suggests that consideration of the ventricular pacemaker function is important in assessing liability to syncope in complete heart block. While patients with Adams-Stokes attacks require pacing it is suggested that all asymptomatic patients with complete heart block and those with minor symptoms are assessed using studies of both ventricular pacemaker function and site. A low risk group not requiring a pacemaker may emerge after sufficient follow-up assessment.

Adams-Stokes seizures due to ventricular tachydysrhythmias in patients with heart block: prevalence and problems of management

One hundred and twelve patients with heart block and chronic tendency to syncope were ECG-monitored during syncope. Ventricular tachycardia and/or fibrillation (VT-VF) was observed as the cause of syncope in 11 patients: in 6 of 20 patients with chronic third degree A-V block, in 3 of 65 with paroxysmal A-V block and in 2 of 27 with S-A block. The R-R interval preceding the escape beat which initiated VT-VF varied between 1.2 and 2.2 seconds. The cerebral attacks were amenable to long-term pacemaker treatment. However, relapses of VT-VF were observed during pacing with a low rate of 55 per minute and during short interruptions in pacing, as produced by intermittent pacemaker failure or threshold determination. In one patient, supplementary treatment with a beta-blocking agent had to be given to suppress exercise-induced attacks of VT-VF after pacemaker implantation.