Juha T. Takkunen

Frequency domain measures of heart rate variability before the onset of nonsustained and sustained ventricular tachycardia in patients with coronary artery disease.

Background. Low heart rate variability (HRV) is associated with an increased risk of arrhythmic death and ventricular tachycardia (VT). The purpose of this study was to examine whether there is a temporal relation between changes in HRV and the onset of spontaneous episodes of VT in patients at high risk of life‐threatening arrhythmias. Methods and Results. Components of HRV in the frequency domain were analyzed before the onset of 28 episodes of nonsustained VT (more than four impulses; duration <30 seconds) and 12 episodes of sustained VT (>30 seconds or requiring defibrillation) in 18 patients with coronary artery disease. Seven patients had survived cardiac arrest not associated with acute myocardial infarction, and 11 had a history of sustained VT. All frequency domain measures of HRV, i.e., total power (p <0.001), high‐frequency power (p <0.05), low‐frequency power (p <0.01), very‐low‐frequency power (p <0.01), and ultralow‐frequency power (p <0.05), were significantly lower before the onset of sustained VT than before nonsustained VT. Total power of HRV was also lower during the 1‐hour period before the onset of sustained VT than the average 24‐hour HRV (p <0.05). An indirect correlation existed between the length of VT and the total power of HRV analyzed during the 15 minutes before the onset of VT (r = 0.54, p < 0.01). HRV had a trend toward increasing values before the onset of nonsustained VT (p < 0.01) but not before the sustained VT episodes. The ratio between low‐frequency and high‐frequency powers increased substantially before both nonsustained and sustained VT episodes (p = 0.06 and p = 0.05, respectively). The rate of VT or the coupling interval initiating the VT did not differ significantly between the nonsustained and sustained VT. Conclusions. Spontaneous episodes of VT are preceded by changes in HRV in the frequency domain. Divergent dynamics of HRV before the onset of nonsustained and sustained VT episodes may reflect differences in factors that can facilitate the perpetuation of these arrhythmias. (Circulation 1993;87:1220‐1228)

Circadian rhythm of heart rate variability in survivors of cardiac arrest

Reduced heart rate (HR) variability is associated with increased risk of cardiac arrest in patients with coronary artery disease. In this study, the power spectral components of HR variability and their circadian pattern in 22 survivors of out-of-hospital cardiac arrest not associated with acute myocardial infarction were compared with those of 22 control patients matched with respect to age, sex, previous myocardial infarction, ejection fraction and number of diseased coronary arteries. Survivors of cardiac arrest had significantly lower 24-hour average standard deviation of RR intervals than control patients (29 +/- 10 vs 51 +/- 15 ms, p less than 0.001), and the 24-hour mean high frequency spectral area was also lower in survivors of cardiac arrest than in control patients (13 +/- 7 ms2 x 10 vs 28 +/- 14 ms2 x 10, p less than 0.01). In a single cosinor analysis, a significant circadian rhythm of HR variability was observed in both groups with the acrophase of standard deviation of RR intervals and high-frequency spectral area occurring between 3 and 6 A.M. which was followed by an abrupt decrease in HR variability after arousal. The amplitude of the circadian rhythm of HR variability did not differ between the groups. Thus, HR variability is reduced in survivors of cardiac arrest but its circadian rhythm is maintained so that a very low HR variability is observed in the morning after awakening, corresponding to the time period at which the incidence of sudden cardiac death is highest.

Evidence of impaired left ventricular performance after an uninterrupted competitive 24 hour run.

The effect of extremely exhaustive exercise on left ventricular performance was studied echocardiographically in 13 experienced male ultramarathon runners who took part in a competitive 24 hr run, completing distances of 114 to 227 km. Although the left ventricular end-diastolic dimension (EDD) was reduced by 7% (54 +/- 5 to 50 +/- 7 mm; p less than .005), the end-systolic dimension (ESD) increased slightly (33 +/- 5 to 34 +/- 6 mm; NS). As a consequence, the stroke dimension (21 +/- 2 to 16 +/- 2 mm; p less than .005) and fractional shortening (38 +/- 5% to 32 +/- 5%; p less than .005) declined by 24% and 16%, respectively. The reduction in fractional shortening was related to delta ESD (r = -.66; p less than .05) but not to delta EDD (r = .22; NS). In spite of reduced afterload, the mean velocity of circumferential fiber shortening also decreased by an average of 9% (p less than .01) in proportion to the distance completed (r = -.69; p less than .01). The systolic blood pressure/ESD ratio was 21% lower after the race (4.2 +/- 0.9 to 3.3 +/- 0.6; p less than .005). Body weight loss was not related to any alterations in left ventricular dimensions or ejection phase indexes. The stroke dimension and ejection phase indexes continued to decline within the last 6 hr of the race but returned to the prerace level 2 to 3 days after the race. Total serum creatine kinase peaked at 3917 to 64740 U/liter (mean 27427) and its MB percentage peaked at 2% to 6%.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive evaluation of the athletic heart: sprinters versus endurance runners.

To evaluate possible differences in the cardiac effects of different types of running training, 22 competing male runners--10 sprinters and 12 endurance runners--were studied with a physical examination, electrocardiography, chest X-ray film and echocardiography. Thirteen sedentary men served as control subjects. There were no differences between the athletic groups in physical findings. However, left ventricular hypertrophy in the electrocardiogram was more apparent in the endurance runners (P less than 0.05), whose relative heart size on chest X-ray examination was also greater than in the sprinters (P less than 0.02). On echocardiography the left ventricular end-diastolic volume was equally greater than normal in both groups of athletes (P less than 0.005), but in the endurance runners the percent chance of the minor axis diameter in systole was greater than in the sprinters or control subjects (P less than 0.02). Values for left ventricular wall thickness and mass were greater than normal in both groups of athletes but were higher in the endurance runners than in the sprinters (P less than 0.001). The left atrial diameter was apparently greater in the endurance runners than in the sprinters or control subjects (P less than 0.001), whereas that of the sprinters did not differ from normal. Thus, intensive sprinter training seems to dilate the left ventricle but causes less increase in wall thickness and mass than training for endurance running and no change in left ventricular function or left atrial size. Endurance running causes left ventricular dilatation equal to that of sprinter training, greater wall hypertrophy and improved systolic emptying of the left ventricle, and it also dilates the left atrium perhaps because of decreased left ventricular compliance.

Pericardial effusion after cardiac surgery: incidence, relation to the type of surgery, antithrombotic therapy, and early coronary bypass graft patency.

To investigate the incidence and clinical significance of postoperative pericardial effusion (PE), the presence of PE was evaluated by echocardiography, 1 and 2 weeks postoperatively, in 50 patients after insertion of a valve prosthesis and in 100 patients after coronary bypass surgery (50 patients receiving a combination of aspirin and dipyridamole and 50 receiving warfarin). PE was found during either procedure in 77% of patients and was marked in 29%. Symptoms of postpericardiotomy syndrome (p less than 0.05), pericardial friction rub (p less than 0.01), atrial arrhythmias (p less than 0.05), cardiac enlargement (p less than 0.01), and pleural effusion (p less than 0.05) were detected more frequently in patients with PE than in those without PE. PE was not related to the type of antithrombotic therapy, the rate of coronary bypass graft occlusion, or the type of cardiac surgery. However, the use of the left internal mammary artery as a coronary bypass graft was associated with a slightly higher incidence of PE (p less than 0.05). One patient (0.7%) required surgical drainage of PE. It was concluded that PE is a common and benign finding after cardiac surgery and usually disappears without specific therapy.

Responses of heart rate variability to coronary occlusion during coronary angioplasty

Signs of sympathetic activation are frequent during the early hours of anterior wall acute myocardial infarction, whereas parasympathetic reflexes predominate in inferior wall acute myocardial infarction. To assess the immediate autonomic responses to acute coronary occlusion, the high-frequency power and root-mean-square successive difference, frequency and time domain measures of heart rate (HR) variability were analyzed in 73 cases of significant (50 to 95%) coronary artery stenosis immediately before and during balloon occlusion (mean 99 seconds). The range of nonspecific changes was formed on the basis of a control group with no ischemia during dilatations of 16 totally occluded coronary arteries. Balloon occlusion of the left anterior descending artery (n = 35) caused an abnormal increase in the measures of HR variability as a sign of vagal activation in 8 patients (23%), and a significant decrease in HR variability in 4 (11%). Occlusion of the left circumflex artery (n = 19) caused an increase in HR variability in 5 patients (26%), and a decrease in 2 (11%). Right coronary artery occlusion (n = 19) caused an increase in HR variability in 5 patients (26%) and a decrease in 4 (21%). Thus, coronary occlusion causes immediate changes in HR variability in greater than one third of patients with coronary artery disease. The direction of these initial HR variability changes cannot be predicted by the site of coronary occlusion.

Augmentation of Atrial Contribution to Left Ventricular Filling in IDDM Subjects as Assessed by Doppler Echocardiography

Left ventricular diastolic function was assessed by pulsed Doppler echocardiography in 21 subjects (mean age 48 yr) with insulin-dependent diabetes mellitus (IDDM) and without evidence of ischemic heart disease and in 21 healthy control subjects of similar age and sex distribution. The peak mitral valve flow velocities during the early rapid filling phase (E) and during late atrial filling (A) were measured, and the ratio of these peak flow velocities (E:A) was calculated. E was similar in both groups, but A was higher (P < .01) in the diabetic group. Thus, E A was lower (1.19 ± 0.24 vs. 1.65 ± 0.67; P <.01) in the diabetic subjects than in the control subjects. On subgroup analysis, 6 patients with cardiac autonomic neuropathy had lower E:A than the patients with no such disorder (0.99 ± 0.15 vs. 1.29 ± 0.25; P < .05). E A was not related to the duration of diabetes, presence of retinopathy, HbA,, or blood glucose levels. In conclusion, the atrial contribution to left ventricular filling seems to be augmented in diabetic subjects. This finding indirectly supports the view that left ventricular compliance is already reduced in asymptomatic diabetic subjects.

Cardiovascular studies on former endurance athletes

Abstract 1. 1. Sixty-one former champion endurance runners or cross-country skiers, 40 to 79 years of age, were submitted to a thorough evaluation of the cardiovascular system. In addition, the study program included a series of anthropometric measurements and a number of laboratory tests. A control group of 54 nonathletes of the same age was submitted to similar studies. The control group consisted of men in sedentary or semisedentary occupations. 2. 2. The former athletes differed from the controls by being shorter, having a smaller sitting height and a smaller body weight, but a larger wrist breadth. There was no difference in ponderal index, knee breadth, biacromial breadth, bicristal breadth, or in the ratio of the two latter measures. 3. 3. Both the mean systolic and diastolic blood pressures of the athletes ( 137 87 mm. Hg ) were significantly lower than those of the controls ( 147 92 mm. Hg ). 4. 4. There was no difference in the serum cholesterol level or in the hemoglobin concentration of the blood between the two groups. 5. 5. Coronary heart disease was diagnosed in 17 of the 54 controls and in 15 of the 61 athletes. Eight control subjects, but only 2 athletes, had had symptoms of coronary disease. 6. 6. The current physical activity was greater in the athletes than in the controls. 7. 7. There were fewer nonsmokers and more heavy smokers, as well as exsmokers, in the control group than in the group of athletes. 8. 8. Among men aged from 40 to 69, the electrocardiogram, by Minnesota Code, showed in 5 of 49 controls and in 1 of 55 athletes Q or QS patterns indicative of old myocardial infarction (I1–3); S-T segment depression at rest (IV1–3), or after submaximal exercise (XI1–3) in 12 of 49 controls and in 8 of 55 athletes; flat or negative T waves at rest or after exercise (v1–3, XII1–3) in 6 of 49 controls and in 4 of 55 athletes. High amplitude R waves (III1) occurred in 6 of 49 controls and in 8 of 55 athletes aged from 40 to 69. In the athletes, high R waves were associated with high level of physical activity (6 of 8) rather than with hypertension (1 of 8); in the controls the association was intimate with hypertension (5 of 6) and loose with physical activity (1 of 6). 9. 9. Twenty-nine of the controls and 38 of the athletes were considered as “healthy” subgroups. The subscapular skinfold of healthy athletes was thinner than that of the controls, whereas there was no significant difference in the upper arm skinfold thickness. As regards the other anthropometric measurements, the comparison of healthy subgroups did not show any essential differences from those revealed by the comparison of the total groups. The systolic blood pressure was lower in healthy athletes than in the controls. 10. 10. Healthy athletes had a larger maximal QRS vector, a larger roentgenologic heart volume, a lower heart rate during exercise, and consequently a higher calculated maximal oxygen uptake, than the controls. 11. 11. The maximal QRS vector showed a statistically significant positive correlation with heart volume in healthy controls but not in healthy athletes. The lack of correlation between these two parameters is considered to suggest that dilatation rather than hypertrophy is the main determinant of the increased heart volume induced by training. 12. 12. The prevalence of electrocardiographic abnormalities in former champion endurance athletes is compared with that observed in other series. “Ischemic” changes occur with the same frequency in former athletes and the general population. However, severe manifestations and subjective symptoms of coronary heart disease may be rarer among athletes.

Comparison of dipyridamole-handgrip test and bicycle exercise test for thallium tomographic imaging

Seventy-three patients with angina pectoris and 20 with atypical chest pain, who underwent coronary angiography, were examined by single-photon emission computed thallium tomography (TI-SPECT) using a combined dipyridamole-handgrip stress test. Perfusion defects were detected in 78 of 81 patients with angiographically significant coronary artery disease (CAD) (sensitivity 96%). In 9 of 12 patients without CAD, the thallium images were normal (specificity 75%). Thirty-five patients with CAD were reexamined by TI-SPECT using a dynamic bicycle exercise stress test. The sensitivity of the dipyridamole-handgrip test did not differ from the bicycle exercise test in diagnosing the CAD (97% vs 94%). Multiple thallium defects were seen in 19 of 22 (86%) patients with multivessel CAD by the dipyridamole-handgrip test but only in 14 of 22 (64%) by the bicycle exercise test. Noncardiac side-effects occurred in 17 of 93 (18%) patients after dipyridamole infusion. Cardiac symptoms were less common during the dipyridamole-handgrip test than during the bicycle exercise (15% vs 76%, p less than 0.01). These data suggest that the dipyridamole-handgrip test is a useful alternative stress method for thallium perfusion imaging, particularly in detecting multivessel CAD.

Effect of open heart surgery on intellectual performance

The interrelationship between postoperative psychosis, neurologic symptoms, and changes in tests of cognitive performance have been studied in a series of 60 cardiac valvular patients who underwent open heart surgery. The effects of preoperative psychological, psychiatric, and cardiologic factors on postoperative cognitive changes were analyzed. The investigation period was from five months before up to five months after the operation. There was a general trend towards improvement in intellectual performances. The psychotic group, however, still showed a persisting impairment in some visual and psychomotor tests several months after the surgery. The group with neurologic symptoms showed impairment in one visual test. Of the preoperative variables, mitral valve disease, a high level of hypochondriasis and anxiety, and poor performance in some visual and psychomotor tests predicted postoperative intellectual impairment. The results suggest two types of cerebral complications of open heart surgery. Postoperative psychosis reflects diffuse brain dysfunction manifesting itself in psychological tests long after the clinical symptoms have resolved. The presence of neurologic symptoms refers to a focal or lateralized injury. Both the neurologic and neuropsychologic findings indicate that the right hemisphere may be prone to dysfunction than the left hemisphere.