Marked Sinus Arrhythmia Research Articles

Cardiac abnormalities in myotonic dystrophy: Electrophysiologic and histopathologic studies

Eight young adult male patients with myotonic dystrophy, mean age 26 years, underwent 24-hour Holter electrocardiographic monitoring and intracardiac electrophysiologic study. Right ventricular endomyocardial biopsies were performed at the end of the electrophysiologic study in five of them. The atrial to His (A-H) interval was 155 msec in one case and ≤ 130 msec in the remaining seven. The His to ventricle interval (H-V) was ≥55 msec in all patients. Twenty-four hour Holter electrocardiographic monitoring demonstrated more than 4 premature ventricular contractions per minute in two patients and marked cyclical sinus arrhythmia during sleep in two others. Electron microscopic analysis of the endomyocardial biopsy specimens disclosed no prominent sarcoplasmic reticulum abnormalities but prominent I bands compared to previously obtained controls. Myofibrillar degeneration was seen in all cases and was associated with abnormal mitochondria in two. Cardiac abnormalities can be detected very early in the evolution of myotonic dystrophy, even prior to the onset of cardiac symptoms. The reported abnormalities appear closely related to the pathologic process affecting other skeletal muscles.

Sleep Apnea Syndrome in a Patient With Shy-Drager Syndrome

A patient with autonomic insufficiency and extrapyramidal signs (Shy-Drager syndrome) and sleep apnea syndrome (SAS) underwent hemodynamic studies. In comparison to patients with SAS and intact autonomic reflexes, systemic hypertension was absent and marked sinus arrhythmia during sleep was blunted. Cyclical pulmonary hypertension associated with frequent apneic episodes during sleep persisted, reflecting a minor role of autonomic reflexes in the generation of this abnormality. Autopsy confirmed the Shy-Drager syndrome and multiple areas of degeneration were observed in areas of the CNS outside the medullary respiratory centers, suggesting their importance in the origin of the respiratory abnormalities in SAS.

ARRHYTHMIAS DOCUMENTED BY 24-HOUR CONTINUOUS ELECTROCARDIOGRAPHIC MONITORING IN 50 MALE MEDICAL STUDENTS WITHOUT APPARENT HEART DISEASE

Results are reported of portable 24 hour dynamic electrocardiographic monitoring in 50 male medical students without cardiovascular disease, as defined by normal clinical and noninvasive cardiovascular examination. During waking periods, maximal sinus rates ranged from 107 to 180 beats/min (mean ± standard deviation 141 ± 17) and minimal rates from 37 to 65 beats/min (mean 53 ± 6). Maximal and minimal observed sleeping rates were, respectively, 70 to 115 (mean 86 ± 9) and 33 to 55 (mean 43 ± 5). Twenty-five subjects (50 percent) had episodes of marked sinus arrhythmia as defined by spontaneous changes in adjacent cycle lengths of 100 percent or more. Fourteen subjects (28 percent) had sinus pauses of more than 1.75 seconds, usually during sinus arrhythmia. Transient nocturnal type I second degree atrioventricular (A-V) block was noted in three subjects (6 percent). Of 28 patients (56 percent) having atrial premature beats, only 1 (2 percent) had more than 100 such beats (141) in 24 hours. Of 25 patients (50 percent) having premature ventricular contractions, only 1 (2 percent) had more than 50 such contractions (86) in 24 hours. In conclusion, frequent atrial and ventricular premature beats are unusual in a young adult male population. In contrast, bradyarrhythmias (including marked sinus arrhythmia with sinus pauses, sinus bradycardia and nocturnal A-V block) are common. These findings are useful in evaluating the clinical significance of arrhythmias detected with portable monitoring.

Sleep-induced apnea syndrome: Prevalence of cardiac arrhythmias and their reversal after tracheostomy

Cardiac arrhythmias during wakefulness and sleep in 15 patients with sleep-induced obstructive apnea, and the effect of atropine and tracheostomy on these arrhythmias were studied by continuous overnight Holter electrocardiographic, respiratory and electroencephalographic recordings. Sleep was characterized by marked sinus arrhythmia in 14, extreme sinus bradycardia (< 30 beats/ minute) in six, asystole of 2.5 to 6.3 seconds in five, second degree atrioventricular (A-V) block in two, and ventricular arrhythmias—complex premature ventricular beats in 10 and ventricular tachycardia in two. Arrhythmias during wakefulness were limited to premature ventricular beats in six. Atropine administration was partially and tracheostomy highly effective in preventing the majority of these arrhythmias during sleep. Marked sinus arrhythmia during sleep is characteristic of the syndrome of obstructive sleep apnea and is frequently accompanied by potentially life-threatening tachy- and bradyarrhythmias. Possible mechanism of production of these arrhythmias, the mode of action of tracheostomy and atropine, and the probable role of similar arrhythmias in the sudden infant death syndrome are discussed.

Mitral valve prolapse with atrioventricular and sinoatrial node abnormalities of long duration

A 20-hear-old patient with mitral valve prolapse and minimal mitral regurgitation associated with intermittent marked sinus bradycardia and sinus arrhythmia, and atrioventricular block, proximal to the bundle of His, varying from first-degree to high-grade, is described. Both the murmur and the atrioventricular block had been documented since the age of eight years, and probably since the first year of life, and has shown no subsequent progression. The patient's symptoms of chest pain and severe lightheadedness and near syncope have been shown by telemetry electrocardiogrphic monitoring to be unrelated to changes in cardiac rhythm.

Arrhythmias documented by 24 hour continuous electrocardiographic monitoring in 50 male medical students without apparent heart disease

Results are reported of portable 24 hour dynamic electrocardiographic monitoring in 50 male medical students without cardiovascular disease, as defined by normal clinical and noninvasive cardiovascular examination. During waking periods, maximal sinus rates ranged from 107 to 180 beats/min (mean +/- 5). Twenty-five subjects (50 percent) had episodes of marked sinus arrhythmia as defined by spontaneous changes in adjacent cycle lengths of 100 percent or more. Fourteen subjects (28 percent) had sinus pauses of more than 1.75 seconds, usually during sinus arrhythmia. Transient nocturnal type I second degree atrioventricular (A-V) block was noted in three subjects (6 percent). Of 28 patients (56 percent) having atrial premature beats, only 1 (2 percent) had more than 100 such beats (141) in 24 hours. Of 25 patients (50 percent) having premature ventricular contractions, only 1 (2 percent) had more than 50 such contractions (86) in 24 hours. In conclusion, frequent atrial and ventricular premature beats are unusual in a young adult male population. In contrast, bradyarrhythmias (including marked sinus arrhythmia with sinus pauses, sinus bradycardia and nocturnal A-V block) are common. These findings are useful in evaluating the clinical significance of arrhythmias detected with portable monitoring.

Sommeil et respiration dans le syndrome “apnee au cours du sommeil” chez l'enfant

A sleep apnea syndrome has been diagnosed in eight children (age range 5–14). Before undertaking therapeutic trials, sleep and respiration were extensively studied. Sleep and respiration were again analyzed 3 months after tonsillectomy and adenoidectomy (6 cases) or tracheostomy with insertion of valve (2 cases). Sleep induced apneic apisodes in these children who had normal respiration during wakefulness. Three types of apnea (central, upper airway, and mixed) were recorded in each case. The minimum number of apneas recorded during a single night was 75; the maximum was 816. Polygraphic monitoring demonstrated greatly disturbed sleep. Sleep changes were quantitative as well as qualitative. REM sleep percent was decreased, but stages 3 and 4 NREM sleep were also impaired. A relationship between stages 3–4 NREM sleep disappeared when apneic episodes were numerous; no apnea was recorded during stage 4 sleep. Follow-up nocturnal recordings of two tracheostomized children with valve open, then closed, confirmed this “stage 4/no apnea” relationship. Apneas were also noted to induce marked sinus arrhythmia during sleep.

Wolff-Parkinson-White Syndrome Observed by Portable Monitoring

Twenty-seven patients with Wolff-Parkinson-White syndrome (preexcitation) were monitored for 24 hours with a portable electrocardiographic recorder. During monitoring, no episodes of paroxysmal supraventricular tachycardia were detected. Despite this, eight patients experienced episodes of palpitation. These episodes reflected sinus tachycardia, premature beating, or no electrocardiographic abnormality. Of the 27 patients, 18 had intermittent preexcitation: 9 had gradual normalization as heart rate increased, 3 had sudden normalization above a critical atrial rate, and 6 had episodic unpredictable normalization of conduction. Thirteen patients had marked sinus arrhythmia, with or without sinus bradycardia, A-V junctional escapes, A-V dissociation, or sinus arrest. We conclude that [1] in a random 24-hour period the average patient with preexcitation does not experience paroxysmal supraventricular tachycardia; [2] symptoms suggesting such tachycardia are misleading; [3] intermittent preexcitation is common, reflecting changing autonomic tone, anomalous pathway refractoriness, or unknown causes; and [4] sinus node dysfunction is frequent in patients with preexcitation.

Unusually Marked Sinus Arrhythmia as a Complication of Acute Diaphragmatic Myocardial Infarction

An instance of markedly irregular sinus arrhythmia associated with acute diaphragmatic myocardial infarction has been described. It is quite unusual to observe an extreme sinus arrhythmia in an adult without the intervention of A-V nodal or ventricular escape rhythm.The influence of digitalis, reserpine, guanethidine and morphine in relation to such cardiac arrhythmia has been discussed.Sinus arrhythmia and/or sinus bradycardia are usually transient and require no treatment unless cardiac output is compromised. This arrhythmia may be mistaken for more serious arrhythmias such as A-V block, S-A block and sinus arrest because of marked irregularity with slowing of the heart rate.

The regulation of stroke volume in the resting, unanesthetized dog

In the resting dog who displays a marked sinus arrhythmia, a model of stroke volume control was tested by a procedure of vectorial reconstruction. In the model, stroke volume is determined by preceding cardiac interval ( I), arterial pressure ( PA), and filling pressure ( PDV). The fit of the model is good; changes in stroke volume are accurately predicted by changes in the other variables. A unit-vector solution indicates the relative importance of each variable. A set of (regression) coefficients indicates how a change in each variable changes the stroke volume. Agreement from run to run and from animal to animal is good. All of the variables— I, PDV, and PA—are necessary to achieve the best prediction of the stroke volume. Each of the variables makes a unique contribution to the stroke-volume changes. If another variable acts in conjunction with those named, its effect is less than that of any of the others. Sympathetic discharge to the heart appears to cause no changes in stroke volume in these resting animals.

CARDIAC ARRHYTHMIAS IN PREMATURE INFANTS

The cardiac rhythm has been monitored in 20 normal premature infants for a period of 5 hours utilizing a slow-speed electrocardiographic tape recorder. In contrast to studies using conventional electrocardiographic techniques, this survey revealed a high incidence of marked sinus arrhythmia, sinus bradycardia, and nodal rhythm.

The effect of atmospheric pressure reduction on the cardiac activity of animals at remote periods after pneumonectomy

Changes of the circulation reaction in conditions of hypoxia were investigated in experiments on pneumonectomized rabbits. The cardiac rhythm was seen to reduce with declining atmospheric pressure (at the altitude of 9–10 km) in conjunction with a marked sinus arrhythmia. ECG exhibits a reduction of the R wave voltage, displacement of the RS-T segment level, the change of the value and direction of the T wave.

Cardiac manifestations in Freidreich's ataxia

Six cases of Friedreich's ataxia have been described, four of which showed classical pictures and two of which were considered to be variants of the disease. Cardiac manifestations were observed in four of these cases; in the remaining two no cardiac changes were noted; these cases, however, showed increased deep reflexes and might be considered as variants of the classical picture. Two patients were admitted to the hospital for treatment of the cardiac disorder and two cases were discovered while the patients were in the hospital during investigations of the neurological disorder. On examination, in addition to the neurological features, a rapid, irregular heart action was noted in three patients, two of whom required treatment for Stokes-Adams-like attacks and acute heart failure. In the third case the rapid, irregular rhythm had resulted in “palpitation” and dyspnea which, however, had not become a major complaint to the patient. In the remaining three patients there were no cardiac symptoms or signs; one of these showed the classical Friedreich's syndrome and electrocardiographic abnormalities. The electrocardiogram revealed multiple auricular and ventricular extrasystoles in three patients, with paroxysms of tachycardia in two of these. One other patient showed only T-wave abnormalities. The remaining two were considered normal, although one showed a marked sinus arrhythmia and minor degree of right axis deviation. Four cases showed significant T-wave abnormalities resembling cardiac infarction, and these occurred in the four patients with absent deep reflexes. A notable feature of these cases was the irregular heart action leading to cardiac insufficiency requiring treatment. This has not been a finding associated with the Friedreich's ataxia but has been reported as the principle clinical feature in familial cardiomegaly. The pathological similarity between Friedreich's disease and familial cardiomegaly is discussed, together with a review of the literature related to the heredo familial variants of Friedreich's ataxia, including a family in which both Friedreich's and heart disease has occurred. From the cases presented in this report there is a close relationship between the cardiac manifestations of the Friedreich's Ataxia and familial cardiomegaly. The pathological similarity, the familial nature, and similar clinical features of both, together with the known variants of the Friedreich group, including families with both Friedreich's ataxia and heart disease (in different members), support the concept that the lethal gene (or faulty germinal mutation) may result in familial heart disease occurring alone within the heredofamilial group of disorders.

Irregularities of the fetal heart: A phonocardiographic study of the fetal heart sounds from the fifth to eighth months of pregnancy

Study of the fetal heart sounds by means of the phonocardiogram has demonstrated that the occurrence of cardiac irregularities in uterine life is not an infrequent discovery. These irregularities can be divided into three general groups, the first two of which constitute about 80 per cent of all the irregularities. The first group consists of an exaggerated physiologic disturbance of the pacemaker mechanism in which a marked sinus arrhythmia develops; this condition persists throughout childhood and finally disappears at the latter end of adolescence. It has no especial clinical significance but it should be recognized in order to make an accurate differential diagnosis from the third and more serious group of irregularities.The second group of fetal arrhythmias consists of a skipping or alteration in the regular rhythm of the heart; this intermission is probably due to an intrauterine extrasystolic arrhythmia. It has been previously described by several authors under different names, but the general impression seems to be that the condition is relatively unimportant inasmuch as it disappears within a few days after delivery. Our own cases substantiate this opinion and we believe that its occurrence is evidence of a hyperirritable myocardium which may be the result of improper hygiene, poor posture, or an unsuitable dietary on the part of the mother. This type of irregularity is not difficult to discover if present, and it must, like the first group of irregularities, be differentiated from the third type.The importance of the fetal irregularities lies primarily in the further investigation of the grossly perverted types of fetal heart rhythms seen in the third group. The combined attention of both obstetrician and cardiologist must be focused upon the mechanism responsible for this change in the cardiovascular system of the fetus. If this condition is due to auricular fibrillation as is suggested by graphic studies of this disease when compared to adult types of auricular fibrillation, indications as to therapy may be made and a new avenue of approach to the possible prevention of certain types of abortion may be accomplished.Widespread clinical application of the phonocardiographic method of examining the fetal heart will undoubtedly add considerable information of extreme importance to the obstetrician; the opportunity presented for a simultaneous study of the fetal and maternal circulations opens up many lines of research in regard to the problems attending gestation. Some of these have previously been hinted at; a study of the various toxemias and other insufficiently understood metabolic disturbances accompanying the pregnant state can be investigated by this method. The prevention of abortion when due to heart disease of the fetus may not be unexpected when a fuller comprehension of the basic causes responsible for the condition is more readily understood by the facts brought to light by the clinical utilization of this new method of examination.