Premature beats in healthy subjects 40-79 years of age

In order to determine the prevalence and complexity of prematurebeats (PBs) in an adult population without apparent heart disease,260 healthy subjects 40–79 years of age had a 24 h ambulatoryECG recording performed. A total of 221 subjects (87%) had one or more atrial prematurebeats (APBs) in the 24 h period, which was statistically significantlymore than the number of subjects (179 or 69%) with ventricularpremature beats (VPBs). Only 19 subjects (7%) had no PBs. Morethan 200 VPBs/24 h were seen in only 5% of the subjects, anda similar percentage had more than 200 APBs/24 h. There wasa statistically significant increase in the number of VPBs aswell as APBs with an increase in age. Multiform VPBs, VPB pairs,multiform APBs and atrial tachycardia (AT) were ‘normal’findings(seen in more than 5% of the subjects), whereas > 2 differentVPB configurations, > 2 episodes of VPB pairs, ventricularbigeminy, R-on-T VPBs, ventricular tachycardia, > 2 episodesof AT and AT with more than 10 beats per episode were ‘abnormal’findings (seen in less than 5% of the subjects). The number of VPBs was almost identical in two 24 h ECG recordingsobtained at a mean interval of 22 months in 17 out of 22 subjectsstudied. Only two out of 22 had a significant change in thenumber of VPBs/24 h over the 22 month period. As a ‘normal’ range for the number of APBs as wellas VPBs per 24 h a figure of 200 is proposed, and it is concludedthat most complex types of PBs may occur as incidental findingsin healthy adult subjects, but usually in small numbers.     

Premature ventricular beats in healthy adult subjects 20 to 79 years of age

111 healthy subjects, 57 males and 54 females, 20–79 yearsof age, randomly selected among the participants of the CopenhagenCity Heart Study were tested for ventricular ectopic activityusing ambulatory 24-h ECG recording.One or more premature ventricularbeats (PVBs) appeared in 68 subjects (61%), 35 males and 33females (61% of each group). The prevalence of PVBs increasedsignificantly with age: 31, 68 and 84% in the respective agegroups: 20–39, 40–59 and 60–79 (P<0.05). The number of PVBs per 24 h was <24 in 88 (79%), <300in 105 (95%), and <500 in 107 (96%). More than 1000 PVBsper 24 h appeared in 3 (2.7%), one of whom had 11 669. The numberof PV Bs per 24 h increased with age, but the increase was notstatistically significant. The number of PV Bs per 100 000 recordedQRS-complexes did not differ significantly from the number ofPV Bs per 24 h. The number of PV Bs h^-1 was highest in daytime, and apparentlyhigher in males than in females. However, the difference betweenthe two sexes was not statistically significant. Multiform PV Bs appeared in 4 subjects, interpolated PV Bs in2, a run of 5 PV Bs in 1, dropped beats in 3, two pauses of1900 ms duration in 1, and several post-acceleration pausesof 1300 ms duration in 1.     

Mean 24 hour heart rate, minimal heart rate and pauses in healthy subjects 40-79 years of age

In order to establish normal limits for mean 24 h heart rate(_t and pauses, 24 h ambulatoryECG recordings from 260 healthy subjects 40–79 years ofage were analysed. The _24h varied from 53 to 95beats/min (mean±2 s.d.: 74±I8 beats/min). Theminimal _t varied from 36 to78 beats/min (mean± 2 s.d.: 56 ±16 beats/min).Analysis of variance showed an additive effect of smoking, sex,leisure-time physical activity and age on both _t, and the effect of the three first factors wasstatistical significant at the 1% level for both heart ratevariables. The males, the non-smokers and the physically activesubjects had a lower _24h anda lower minimal _t than females,smokers and passive subjects. Older subjects had a lower _t was non-significant. A total of 77 subjects (30%) had a pause (R-R interval1500 ms),but in only 12 (5%) did the pause exceed 1750 ms with the longestpause measuring 2040 ms. Further analysis of the longest pausein each of the 77 subjects with pauses showed that 46 of thelongest pauses occurred at night following a gradual decreasein the R-R intervals for a few beats (‘post-accelerationpauses’). In 12 subjects the longest pause was causedby sinus arrest, and in nine cases a blocked atrial prematurebeat was thought to be present. Wenckebach A- V block was seenin only two subjects. It is concluded that sex, age, smoking and leisure-time physicalactivity are all factors that have to be considered for a thoroughevaluation of heart rate variables in the 24 h ambulatory ECG.     

Heart rate turbulence after ventricular and atrial premature beats in subjects without structural heart disease

INTRODUCTION: Studies assessing heart rate (HR) behavior after premature beats have focused on HR responses to ventricular premature beats (VBPs), but there is less information of HR behavior after atrial premature beats (APBs). METHODS AND RESULTS: HR turbulence after VPBs and APBs was first measured in response to ambient APBs and VPBs occurring during 24-hour ambulatory ECG recordings in 29 subjects without structural heart disease, and in response to programmed atrial (AE) and ventricular extrastimuli (VE) in 6 subjects undergoing electrophysiologic (EP) examination. Turbulence onset (TO) was more negative (-2.3 +/- 3.2% vs -0.9 +/- 2.8%, P < 0.01) and turbulence slope (TS) was steeper (11 +/- 11 vs 5.1 +/- 4.1 msec/R-R interval, P < 0.05) after VPBs than APBs. Compared to VPBs, the acceleration of HR after APBs was delayed by one beat, and APBs were associated with a short R-R interval preceding the APB, resulting in a blunted TO. Studies of patients undergoing an EP test confirmed the one-beat delay of HR acceleration and the blunted TO after programmed AE compared to VE (P < 0.05). TO and TS after VPBs were related to baroreflex sensitivity. TO also was related to 24-hour standard deviation of N-N intervals (SDNN). However, the TO or TS following APBs was not related to either SDNN or baroreflex sensitivity. CONCLUSION: HR behavior is different in response to APBs and VBPs among subjects without structural heart disease. Different definitions and calculation formulas should be used in the analysis of HR turbulence after APBs and VPBs.     

Reliability of serial 24 h ambulatory electrocardiography in predicting cardiac death after myocardial infarction

One hundred consecutive patients below the age of 70 years,surviving an acute myocardial infarction, were subjected to24-h electrocardiographic monitoring during the late hospitalphase, as well as at one, three and six months after the infarction.Complex ventricular arrhythmias (multiform, couplets, R on T,ventricular tachycardia) were found in 34, 51, 41 and 39% ofthe patients on the four occasions, respectively. Thus a significantincrease was found in relation to discharge (34 v. 51%, P <0.05).The cumulative percentage of patients with complex arrhythmiaswas 34, 65, 74 and 79% respectively, indicating a considerableintra-individual variation from time to time. Complex ventriculararrhythmias were found in only six patients during all monitorings.A close correlation between the quantitative and qualitativearrhythmia pattern was demonstrated. Nineteen cases of cardiacdeath occurred during an average follow-up period of 30 (range27–34) months. During the late hospital phase, but notafterwards, complex ventricular arrhythmias were significantlymore frequent in patients who subsequently had cardiac death(P <0.05). In 11 patients who had cardiac death, their finalmonitoring was without complex ventricular arrhythmias. As thesearrhythmias were demonstrated in the large majority of patientsand showed a considerable variation from time to time in theindividual patient, even serial 24 h ambulatory electrocardiographyhas severe limitations in identifying well-defined high or lowrisk groups after myocardial infarction.     

Five-year follow-up of 101 elderly subjects by means of long-term ambulatory cardiac monitoring

Long-term follow-up of 101 healthy elderly subjects living independentlyin the community has been undertaken by means of clinical examination,resting ECG and 24-hour ambulatory cardiac monitoring. It appearsthat the finding of ventricular premature complexes at the rateof 10 per hour or greater is associated with a significant increasein mortality. The prevalence of atrial fibrillation, initiallyfound to be 11% rises with age to 17% by the age of 84 years.Long-term ambulatory monitoring is essential in the proper documentationof paroxysmal atrial fibrillation. Bundle branch block also occurs in over 10% of elderly peopleand the prevalence rises steeply with age, so that at the endof this study more than one quarter of the survivors had evidenceof His–Purkinje disease. Over 5% of our subjects had definiteindications for pacing during the period of follow-up and lendssupport to the opinion that the current pacemaker implantationrate in the United Kingdom is below the optimal level.     

Minimal heart rates and longest pauses in healthy adult subjects on two occasions eight years apart

A 24-h Holter monitoring (HM) record was obtained on two occasions8 years apart in 183 healthy subjects (120 male and 63 female),aged 40–85 years. The purpose of the study was to determinethe minimal mean heart rate (-min) and longest pauses in heart rhythm, and to examine possiblechanges in these parameters over a longer period of time. (-min was calculated from a I-min sampleperiod.) -min was influenced by physical activity level and smoking habit, but was independentof age. Females had higher than males. In the male group mean was 54 beats min^–1 and 53 beats min^–1 on the tworecordings (P>0·05) (range 36–75 beats min^–1and 38–69 beats min^–1). <40 beats min^–1 was seen in 2·5% of the males.In the female group, the lowest recorded HR was 42 beats min^–1and mean on the two recordings was 58 beats min^–1 and 56 beats min^–1 (P<0001).The paired observations were highly correlated. In all subjects, pauses > 1·75s were registered in 6% and6·5% on the two recordings.The occurrence of pauses was related to low . Above the age of 60 years sinus arrest was thetype of pause most often seen. It is concluded that (1) <40 beats min^–1 and pauses> 2·0 s are rare events in non-athletes, and shouldbe considered abnormal; (2) for a given individual, , seems to be a stable parameter overlong periods of time, but is influenced by sex, smoking andphysical activity; (3) limits for in an adult population can be determined from one 24-h HM.     

Prevalence and prognostic significance of exercise-induced silent myocardial ischemia detected by thallium scintigraphy and electrocardiography in asymptomatic volunteers

Although a silent ischemic electrocardiographic response to treadmill exercise in clinically healthy populations is associated with an increased likelihood of future coronary events (i.e., angina pectoris, myocardial infarction, or cardiac death), such a response has a low predictive value for future events because of the low prevalence of disease in asymptomatic populations. To examine whether detection of reduced regional perfusion by thallium scintigraphy improved the predictive value of exercise-induced ST segment depression, we performed maximal treadmill exercise electrocardiography (ECG) and thallium scintigraphy (201Tl) in 407 asymptomatic volunteers 40-96 years of age (mean = 60) from the Baltimore Longitudinal Study on Aging. The prevalence of exercise-induced silent ischemia, defined by concordant ST segment depression and a thallium perfusion defect, increased more than sevenfold from 2% in the fifth and sixth decades to 15% in the ninth decade. Over a mean follow-up period of 4.6 years, cardiac events developed in 9.8% of subjects and consisted of 20 cases of new angina pectoris, 13 myocardial infarctions, and seven deaths. Events occurred in 7% of individuals with both negative 201Tl and ECG, 8% of those with either test positive, and 48% of those in whom both tests were positive (p less than 0.001). By proportional hazards analysis, age, hypertension, exercise duration, and a concordant positive ECG and 201Tl result were independent predictors of coronary events. Furthermore, those with positive ECG and 201Tl had a 3.6-fold relative risk for subsequent coronary events, independent of conventional risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence and prognostic significance of ventricular arrhythmias in individuals without detectable heart disease

The spontaneous incidence of ventricular arrhythmias was documentedin 170 individuals (age 18–70 years; mean age 42 years)without identifiable cardiovascular disease using 24 h continuousambulatory electrocardiography. The study group consisted of117 males and 53 females. In 104 individuals cardiac diseaseswere excluded clinically, all of them free of cardiac symptomsand with normal clinical findings including 12-lead ECG; allsubjects of 40 years of age or older were included only afterobtaining an exercise ECG without horizontal or down-slopingST-segments and with a physical working capacity of at least80%. A second subgroup of 66 individuals showed normal coronaryangiograms, normal left ventriculography and having haemodynamicswithin the normal range. One hundred ‘normals’ (59%)showed no ectopic activity during 24 h electrocardiography.In contrast, 41 (24%) demonstrated ventricular extrasystoles(VES) at times (1–24 VES/24 h). 12 (7%) had a moderateincidence of 24–240 VES per 24 h, nine (5%) a high incidenceof 241–2400 VES and eight (5%) an excessive incidenceof > 2400 VES. With regard to qualitative criteria of VES,45 out of 170 individuals (26%) had uniform VES whereas in 25(15%) VES were of multiform configuration. Ventricular bigeminywas detected in three individuals and consecutive VES in 11subjects (6%). However, only three of the latter demonstratedventricular tachycardia consisting of three consecutive VESor more. In only two individuals were early VES interruptingthe preceding T-wave (‘R on T-VES’) documented.Thus, VES are common findings in subjects without detectablecardiovascular diseases. Frequent and complex VES are however,rarely documented during ambulatory electrocardiography. Prevalence of VES in ‘normals’ was independent ofsex, type of coronary vascular supply, and heart rate. However,there was a significant increase in ectopic activity with increasingage (P <0.01). After a mean follow-up period of 4.6 years (range: 23–91months) we obtained information on 24 out of 28 individualsshowing frequent and/or complex VES (multiform VES, bigeminyand/or consecutive VES) at entry into the study. All individualsof this group of interest survived having been without any cardiacmedication during the follow-up period. Thus, frequent and complexVES do occur at times in subjects without identifiable cardiovasculardisease. But our results suggest that they do not indicate apoor prognosis with regard to sudden cardiac death.     

Long-term prognostic significance of ambulatory electrocardiographic findings in apparently healthy subjects greater than or equal to 60 years of age.

To determine the long-term prognostic significance of frequent or complex ectopic beats and ST-segment changes on 24-hour ambulatory electrocardiogram (ECG) in apparently healthy older subjects, 98 volunteers were followed up from the Baltimore Longitudinal Study of Aging who were 60 to 85 years old and free of cardiac disease by history, physical examination and maximal treadmill testing at the time of ambulatory ECG between 1978 and 1980. Over a mean follow-up period of 10 years, coronary events developed in 14 subjects: angina pectoris in 7, nonfatal myocardial infarction in 3 and sudden cardiac death in 4. The incidence of coronary events did not differ significantly between subjects who developed the following arrhythmias and those who did not, respectively: greater than or equal to 30 supraventricular ectopic beats in any hour, 18 vs 13%; greater than or equal to 100 supraventricular ectopic beats in 24 hours, 20 vs 12%; paroxysmal atrial tachycardia, 15 vs 14%; greater than or equal to 30 ventricular ectopic complexes (VECs) in any hour, 17 vs 14%; greater than or equal to 100 VECs in 24 hours, 18 vs 14%; or repetitive VECs, 20 vs 13%. The mean 24-hour heart rate (75 +/- 8 vs 72 +/- 9 beats/min) as well as the maximal (116 +/- 20 vs 111 +/- 18 beats/min) and minimal (51 +/- 6 vs 53 +/- 7 beats/min) heart rate also did not differ between the coronary event and non-event groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence and significance of exit block during arrhythmias arising in pulmonary veins

INTRODUCTION: Recent studies described the occurrence of conduction block within pulmonary veins. The purpose of this study was to evaluate the prevalence of exit block during arrhythmias that arise in pulmonary veins. METHODS AND RESULTS: Twenty-five patients with atrial tachycardia/fibrillation underwent successful ablation of 28 arrhythmogenic foci within a pulmonary vein. The prevalence of exit block in the pulmonary veins was determined in 28 arrhythmogenic pulmonary veins and 40 nonarrhythmogenic pulmonary veins. During isolated premature depolarizations, exit block in a pulmonary vein was observed at 50% of arrhythmogenic pulmonary vein sites and was never observed within pulmonary veins that did not generate a tachycardia (P < 0.01). During tachycardia, exit block from a pulmonary vein was observed in 61% of the arrhythmogenic pulmonary veins. The mean cycle length of the pulmonary vein tachycardias associated with exit block was significantly shorter than the cycle length of tachycardias that were not associated with exit block (163 +/- 32 vs 251 +/- 45 msec, P < 0.001). Exit block in two pulmonary veins during the same episode of tachycardia was observed in 3 of the 28 arrhythmogenic pulmonary veins (11%) in three different patients. Simultaneous recordings in the two pulmonary veins demonstrated bursts of tachycardia in both veins that were not synchronized. Radiofrequency catheter ablation of the arrhythmogenic site in one of the pulmonary veins eliminated spontaneous recurrences of tachycardia from the other pulmonary vein. CONCLUSION: Exit block from pulmonary veins is a common observation during tachycardias generated within pulmonary veins and indicates that an arrhythmogenic pulmonary vein has been identified. The occurrence of exit block in more than one pulmonary vein most likely is attributable to simultaneous tachycardias, one or both of which may be tachycardia induced and perpetuated by the other.     

老年持续不卧床腹膜透析患者中的胃食管反流病发生率及相关因素分析

目的评估老年持续不卧床腹膜透析（CAPD）患者胃食管反流病（GERD）的发生率及探讨可能的相关影响因素。方法采用胃食管反流病问卷（RDQ）对56例腹膜透析患者进行评分,≥12分者考虑胃食管反流病。按年龄分为老年组（年龄≥60岁）和非老年组（年龄〈60岁）,比较两组之间在一般临床资料、腹膜透析相关指标、营养指标、钙磷代谢指标、炎症指标以及RDQ分值之间的差异,并评估各指标与RDQ分值之间的相关性。结果老年与非老年CAPD患者在体重指数（BMI）、腹透龄、日透析液量及每周尿素清除指数（Kt／V）方面差异均无统计学意义,老年组每周总肌酐清除率（Ccr）较非老年组患者增高,P=0．031;两组在营养指标、钙磷代谢指标及炎症指标方面差异无统计学意义。按照RDQ诊断的GERD的发生率,老年组为18．52％,非老年组为13．79％,差异无统计学意义;老年组平均RDQ得分为4．07±5．27,非老年组平均RDQ得分为3．90±6．74,差异无统计学意义,P〉0．05。RDQ分值与每日透析液量呈正相关,（r=0．349,P=0．009）。结论老年CAPD患者RDQ总体得分及GERD的发病率高于非老年CAPD患者,差异是否有意义尚需大型临床试验证实。RDQ分值和每日透析液量呈正相关,与其他透析相关凶素的相关性尚需进一步验证。     

Prevalence and magnitude of S-T segment and T wave abnormalities in normal men during continuous ambulatory electrocardiography

Fifty asymptomatic normal male volunteers, mean age 44.6 years (range 35 to 59), were prospectively studied to ascertain the prevalence and magnitude of S-T segment and T wave changes detected during continuous ambulatory electrocardiographic monitoring. Transient S-T segment depression of 1.0 mm or more was recorded in 15 (30 percent) of the subjects, and labile T wave inversion of up to 3 mm occurred in an additional 18 (36 percent). The presence of ST-T changes during monitoring did not correlate with age, daily activity status or heart rate. There was also no correlation with the S-T segment response or work performance during treadmill exercise testing. It is concluded that S-T segment depression and T wave inversions are commonly observed during ambulatory electrocardiographic monitoring of normal men. Therefore, similar changes observed in patients with coronary artery disease should be interpreted with caution.     

Left ventricular false tendons in children: Prevalence as detected by 2-dimensional echocardiography and clinical significance

During a 28-month period, consecutive 2-dimensional echocardiograms were reviewed to determine the prevalence of left ventricular (LV) false tendons, their associated anomalies and clinical significance. LV false tendons were found in 31 (0.8%) of 3,847 consecutive 2-dimensional echocardiograms. Of 31 LV false tendons, 30 passed longitudinally from papillary muscle to septum and 1 went from free wall to free wall. The 31 patients were aged 1 day to 15 years. Associated heart disease, most often ventricular septal defect, bicuspid aortic valve and coarctation of the aorta, was present in 48%, of whom 73% were girls. Of those without heart disease, 69% were boys. In patients with heart disease, precordial murmurs were due to the underlying cardiac anomaly. Of those without heart disease, 15 of 16 (94%) had a precordial murmur, usually of the Still's type over the lower left sternal border. Four of 31 (13%), 1 with and 3 without heart disease, had unifocal premature ventricular contractions that were rate-dependent in the 2 patients undergoing stress testing. LV false tendons appear to occur in 0.8 % of pediatric patients and usually are accompanied by a Still's type innocent murmur if unassociated with heart disease. Some LV false tendons are associated with rate-dependent premature ventricular contractions.     

Prevalence and prognostic significance of silent myocardial ischaemia detected by exercise test and continuous ECG monitoring after acute myocardial infarction

The incidence and prognostic significance of silent myocardial ischaemia in 165 patients who survived a first acute myocardial infarction were assessed by means of maximal exercise stress test and 24 h continuous ECG monitoring performed before discharge. During the 1 year follow-up period 10 cardiac deaths occurred; moreover seven patients suffered a fatal myocardial re-infarction and 14 developed unstable angina. Cardiac death occurred in five of 40 patients (12.5%) with ST segment depression on stress test by in only three of 117 (2.6%) without ST segment changes (P less than 0.01). One-hundred-and-three of 117 patients (88.0%) without angina or ST segment depression on stress testing survived 1 year without cardiac events, compared with 24 of 40 patients (60.0%) with ST segment depression whether or not associated with angina (P less than 0.001). Cardiac death occurred in five of 25 patients (20.0%) with ST segment depression on continuous ECG monitoring, compared with five of 140 (3.6%) without (P less than 0.01). One-hundred-and-seventeen out of 140 patients (83.6%) without angina or ST segment depression survived 1 year follow-up without cardiac events, compared with 13 of 25 (52.0%) with ST segment depression with or without angina (P less than 0.01). Classifying patients in a 2 x 5 contingency table according to the occurrence of ST segment depression on exercise testing and/or ECG ambulatory monitoring, the Yates corrected chi-square test showed a significant pattern when cardiac deaths and cardiac events were considered together (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)