Heart rate variability during repeated arterial occlusion in coronary angioplasty

Temporal Release of High-Sensitivity Cardiac Troponin T and I and Copeptin After Brief Induced Coronary Artery Balloon Occlusion in Humans

BACKGROUND

Cardiac troponins (cTns) are the cornerstone of diagnosing acute myocardial infarction. There is limited knowledge on the duration of ischemia necessary to induce a measurable release of cTns or the very-early-release kinetics of cTns after an ischemic event. Copeptin may have a supplementary role in ruling out myocardial infarction early. We investigated the release of cTns and copeptin in the first hours after experimental balloon-induced ischemia in humans.

METHODS

Thirty-four patients (median age, 60 years [interquartile range, 51-64]; 15 men, 43%) with angiographically normal coronary arteries were randomly assigned into 4 groups with different durations of induced myocardial ischemia (0, 30, 60, 90 s). Ischemia was induced by inflating a balloon in the left anterior descending artery between the first and second diagonal branch. Blood was collected before balloon inflation (baseline) every 15 minutes for the first 3 hours, and every 30 minutes for the next 3 hours. The cTns were analyzed by 3 high-sensitivity (hs) cTn assays: hs-cTnT (Roche), hs-cTnI (Siemens), and hs-cTnI (Abbott). Copeptin was analyzed by a sandwich immunoluminometric assay.

RESULTS

None of the patients had any complications. Increased cTn concentrations were detected by all 3 assays, and the magnitude of the increase was associated with the duration of ischemia. Increased hs-cTnI (Siemens) concentrations were first detectable 15 minutes after 90-s ischemia (median 43.7% increase) and increased more steeply and had a higher peak than the other assays. Copeptin levels did not significantly change. Using the cTnT, hs-cTnI (Siemens), and hs-cTnI (Abbott) concentrations at 0 and 180 minutes, 1 (11%), 0, and 0 patients from the 60-s ischemia group and 5 (63%), 2 (25%), and 1 (11%) from the 90-s ischemia group, respectively, fulfilled criteria for a biochemical myocardial infarction.

CONCLUSIONS

This study is the first to report the early-release kinetics of cTn concentrations after different durations of experimental coronary balloon occlusion in humans. All assays detected a cTn increase after only 30 s of ischemia. hs-cTnI (Siemens) rose faster and reached a higher peak. Copeptin levels did not change significantly. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03203057.

Spectral analysis related to bare-metal and drug-eluting coronary stent implantation

BACKGROUND

The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia.

OBJECTIVE

To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent.

METHODS

This study assessed 61 patients (mean age, 64.0 years; 35 men) with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform), measuring the low-frequency (LF) and high-frequency (HF) components, and the LF/HF ratio before and during the procedure.

RESULTS

Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively), with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00). The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment.

CONCLUSIONS

Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.

Heart-rate changes in asphyxic preconditioning in rats depend on light-dark cycle

Generally, it is assumed that heart-rhythm disorders during hypoxia result from the interplay between the autonomic nervous system (ANS) and the direct effect of hypoxia on cardiorespiratory structures of the central nervous system and on the myocardium. Circadian variability in the ANS may substantially influence the electrical stability of the myocardium, and thus it is associated with the preconditioning protective mechanism. We designed our study using anaesthetized Wistar rats (ketamine/xylazine 100 mg/15 mg/kg, i.m., open chest experiments) to evaluate the effect of preconditioning (PC) induced by 1 to 3 cycles (1 PC–3 PC) of asphyxia (5 min. of artificial hypoventilation, VT = 0.5 ml/100 g of b.w., 20 breaths/min.) and reoxygenation (5 min. of artificial ventilation, VT = 1 ml/100 g of b.w., 50 breaths/min.) on the heart rate (HR) during followed exposure 20 minutes of hypoventilation after adaptation to a light-dark (LD) cycle of 12 hours:12 hours. Hypoxic HR increases were only minimally prevented by 1 to 2 PC pre-treatment, particularly during the dark part of the day. A statistically significant HR increase required 3 PC and was seen only in the light part of the day. We concluded that possible ANS participation in asphyxic preconditioning depends not only on the number of preconditioned cycles but also on the LD cycle, when the ANS participation in preconditioning can be effective only in the light (nonactive) period.

Impact of shock wave lithotripsy on heart rate variability in patients with urolithiasis

The physiological response of the cardiac autonomic nervous system during shock wave lithotripsy (SWL) remains unclear. Heart rate variability (HRV) is an index of cardiac autonomic balance. This study aimed to analyze HRV during SWL in patients with urolithiasis. Electrocardiograms of patients who underwent SWL were obtained. Recordings were obtained before and after SWL. For each time point, the recordings were obtained continuously for 6 min, after which R wave-to-R wave (RR) intervals were extracted. The time digital sequence derived from RR intervals was the HRV signal. Time-domain analysis revealed that the mean of RR intervals (MRR) and standard deviation of normal beat-to-normal beat (NN) intervals (SDNN), but not the square root of the mean squared difference of successive NNs (RMSSD) or triangular interpolation of NN intervals (TINN), significantly increased during SWL. The increase in SDNN persisted after SWL but MRR returned to the initial level. Frequency-domain analysis revealed that very low frequency (VLF), low frequency (LF), and LF/high frequency (HF) ratio significantly increased after SWL, while there was no statistically significant difference in HF. Thus, the patients had significantly high MRR and SDNN during SWL and significantly high SDNN, VLF, LF, and LF/HF ratio after SWL. SWL could alter the functioning of the cardiac autonomic nervous system, resulting in reduction in sympathetic activity and increase in parasympathetic activity. Further studies with larger samples are required to confirm these findings and understand the underlying mechanisms.

Multiple Factor Analysis of the Autonomous Nervous System during PTCA

This study describes the Autonomic Nervous System (ANS) response before, during and after a percutaneous transluminal coronary angioplasty (PTCA). The study population consisted of 37 patients undergoing PTCA from Staff-3 Database. Classical Heart rate variability (HRV) parameters: RR mean, SD, rMSSD, LF, HF, LF/HF and LF/(HF+LF) were extracted and a multiple factorial analysis (MFA) was carried out. Preliminary results show that sympathetic activity increases during and after PTCA, and global HRV decreases during PTCA and increases after PTCA. These findings suggest that MFA provides a powerful tool allowing assessment of ANS's response during PTCA.

Heart rate variability estimates of autonomic tone: relationship to mapping pathological and procedural stress responses in coronary disease

Many lines of experimental evidence suggest the interplay of the autonomic nervous system and a variety of mediators of vascular atheroma and ultimately vascular occlusion. In vivo study in human volunteers and patients is hampered by the lack of a reliable and sensitive marker of prevailing autonomic tone able to reflect the appropriate dynamic change in nervous activity. Currently, the modern standard for definition of autonomic tone is based on a variety of analyses of R-R interval variability from the surface ECG. In this review, we consider whether heart rate variability techniques are sensitive enough to define relevant clinical interactions between neural tone and other mediators of vascular occlusion--specifically, mechanical pressure, thrombotic and hormonal factors--which are relevant to atherosclerotic vascular disease.

Effect of the final coronary arterial diameter after coronary angioplasty on heart rate variability responses

BACKGROUND

Autonomic nervous system dysfunction and reduced heart rate variability (HRV) after percutaneous transluminal coronary angioplasty (PTCA) were reported in patients with coronary artery disease. However, factors related to reduced HRV are not clearly demonstrated. The aim of the present study was to assess the relationship between HRV indices and the final coronary arterial luminal diameter after PTCA.

METHODS

Twenty-seven patients (23 male, 4 female, mean age: 52.5 +/- 7.1 years) with single vessel disease were included in the study. PTCA was performed in all patients. Low-frequency power (LFP), high-frequency power (HFP), and total power (TP) were calculated by using frequency-domain analysis of HRV. All examinations were performed 24 hours before, and 24 hours, 10 days, and 30 days after PTCA. The patients were divided into groups according to the PTCA restenosis risk score, the degree of dilatation, and revascularization after coronary angioplasty.

RESULTS

The groups were comparable for age, gender, and coronary artery risk factors. HRV was found to be reduced in 76% of patients. Reduction in HRV after PTCA was significantly related to the PTCA risk score and the degree of revascularization (r = 0.48, P < 0.01 and r = 0.50, P < 0.008). Reduction in HRV was more significant in patients with previous myocardial infarction (P < 0.05). Recovery of HRV occurred on the tenth day after PTCA.

CONCLUSION

Transient and rapidly recovered, especially parasympathetically modulated HRV reduction occurred after PTCA in patients with single-vessel disease. HRV reduction is associated with PTCA restenosis risk score and the degree of revascularization as invasive feature of angioplasty, hence it may be related to reperfusion.

The antiarrhythmic effects of ischaemic preconditioning in anaesthetized dogs are prevented by atropine; role of changes in baroreceptor reflex sensitivity

1. Dogs, anaesthetized with chloralose and urethane, were subjected to a 25 min occlusion of the left anterior descending coronary artery. This resulted in ventricular ectopic activity, a reduction in baroreflex sensitivity (BRS, measured following the intravenous administration of phenylephrine), elevations in the epicardial ST-segment and increases in the degree of inhomogeneity of electrical activation, both measured from the ischaemic region of the left ventricular wall. 2. These changes were markedly reduced when the 25 min occlusion was preceded, 20 min earlier, by a 5 min (preconditioning) occlusion of the same coronary artery (e.g. VF during ischaemia reduced from 40% in the controls to 0%; P<0.05; BRS increased from 1.22+/-0.23 pre-occlusion to 1.61+/-0.25 mmHg ms(-1) post-occlusion in preconditioned dogs; cf. 1.28+/-0.29 to 0.45+/-0.12 mmHg ms(-1) respectively in the controls, P<0.05). 3. These beneficial effects of preconditioning were prevented by the administration, 10 min prior to the 25 min coronary artery occlusion, of atropine (1 mg kg(-1) i.v. followed by a continuous infusion of 0.04 mg kg(-1) h(-1)). For example, VF during occlusion was increased from 0% in the preconditioned dogs to 40% (P<0.05) in the presence of atropine and BRS was again reduced during occlusion (from 1.75+/-0.29 to 0.30+/-0.08 mmHg ms(-1); P<0.05). 4. We conclude that preconditioning reduces arrhythmia severity during ischaemia by favourably modifying cardiac autonomic receptor mechanism through enhancing vagal influences.

Preinfarction angina protects against out-of-hospital ventricular fibrillation in patients with acute occlusion of the left coronary artery

OBJECTIVES

The goal of this study was to evaluate the effect of preconditioning on out-of-hospital ventricular fibrillation (VF) in patients with acute myocardial infarction (AMI).

BACKGROUND

More than half of the deaths associated with AMI occur out of the hospital and within 1 h of symptom onset. In humans, preinfarction angina (PA), which can serve as a surrogate marker for preconditioning, reduces infarct size, but the protective effect against out-of-hospital VF has not been investigated.

METHODS

Preinfarction angina status and acute coronary angiographic findings of 72 consecutive patients with AMI complicated by out-of-hospital VF were compared with 144 matched controls without this complication.

RESULTS

Preinfarction angina is associated with a lower risk for VF (odds ratio [OR]: 0.40, 95% confidence interval [CI]: 0.18 to 0.88). In patients with acute occlusion of the left coronary artery (LCA) (n = 136), the risk reduction is pronounced (OR: 0.25, 95% CI: 0.10 to 0.66), whereas, in patients with acute occlusion of the right coronary artery (RCA) (n = 67), the protective effect of PA on VF was not observed (OR: 2.25, 95% CI: 0.45 to 11.22). Subgroup and multivariate analyses show that the protective effect is independent of cardiovascular risk factors, preinfarction treatment with beta-adrenergic blocking agents or aspirin, the presence of collaterals or residual antegrade flow or the extent of coronary artery disease.

CONCLUSIONS

Preinfarction angina protects against out-of-hospital VF in patients with acute occlusion of the LCA. This protection is independent of risk factors or coronary anatomy. A larger study is needed to examine the apparently different effect in patients with acute occlusion of the RCA.

Autonomic mechanisms and sudden death after abrupt coronary occlusion

In spite of recent advances in secondary prevention, sudden cardiac death has remained a major public health problem as the majority of fatalities occur in subjects without a history of severe heart disease. Abrupt rupture of a vulnerable plaque resulting in thrombotic occlusion of a coronary artery is a common cause of sudden death in this population. Coronary occlusion does not, however, invariably lead to sudden death but may cause acute myocardial infarction or exacerbation of chest pain. Extensive studies in experimental animals and increasing clinical evidence indicate that autonomic nervous activity has a significant role in modifying the clinical outcome. Sympathetic hyperactivity favours the genesis of life-threatening ventricular tachyarrhythmias while vagal activation exerts an antifibrillatory effect. Strong afferent stimuli from the ischaemic myocardium impair arterial baroreflex and may lead to dangerous haemodynamic instability. Studies with a human angioplasty model have shown that there is wide interindividual variation in the type and severity of autonomic reactions during the early phase of abrupt coronary occlusion, a critical period for out-of-hospital cardiac arrest. The site of the occlusion is not a significant determinant of the reactions, whereas the severity of a coronary stenosis, adaptation or ischaemic preconditioning, beta-blockade and gender seem to affect the autonomic reactions and occurrence of complex ventricular arrhythmias. Clinical and angiographic factors are, however, poor predictors of autonomic reactions in an individual patient. Recent studies have documented a hereditary component for autonomic function, and genetic factors may also modify the clinical manifestations of acute coronary occlusion.

Arterial baroreflex impairment in patients during acute coronary occlusion

OBJECTIVES

We tested whether acute coronary occlusion interferes with arterial baroreceptor control of heart rate in humans.

BACKGROUND

Subnormal baroreflex sensitivity (BRS) is an important risk indicator for sudden death. Animal research indicates that both chronic myocardial infarction and acute coronary occlusion impair baroreflex modulation of heart rate.

METHODS

We measured RR interval prolongation after phenylephrine-induced systolic pressure increases before and during 2-min coronary occlusions in 47 patients (27 men) undergoing clinically indicated single-vessel coronary angioplasty for stenoses in the proximal or midportion of the vessel causing >50% reduction in the arterial diameter, with normal antegrade flow (33 anterior descending, 10 circumflex, 4 right coronary artery). A control group of 11 patients treated for chronic total occlusion of a coronary artery was assessed to evaluate nonspecific changes in baroreflex function during a 2-min balloon inflation in the occluded artery.

RESULTS

The BRS decreased from 5.2+/-3.8 (mean+/-SD) to 4.1+/-3.5 ms x mm Hg(-1) (p=0.01) during the coronary occlusion in the 28 patients with preserved arterial baroreceptor control of heart rate-that is, adequate blood pressure responses and correlation coefficients of the slopes both in baseline and during coronary occlusion. The same phenylephrine dose increased systolic pressure less during than before coronary artery occlusion (21+/-21 versus 36+/-16 mm Hg, p < 0.0001), and in 6 patients it failed to prevent systolic pressure reduction during occlusion. Correlation coefficients of the baroreflex regressions decreased from 0.81+/-0.27 to 0.47+/-0.44 (p < 0.0001) during coronary artery occlusion in the 41 patients with adequate systolic pressure rises in both phenylephrine tests, and the association between RR intervals and rising systolic pressures was lost in 13 patients during coronary occlusion. Balloon inflation in a chronic total occlusion of a coronary artery did not cause significant changes in BRS (from 5.3+/-4.0 to 5.2+/-3.7 ms x mm Hg(-1)), correlation coefficient of the slope or phenylephrine-induced pressure rise.

CONCLUSIONS

Our study shows that abrupt coronary occlusion impairs baroreflex modulation of vagal and sympathetic nervous outflow in humans.

Heart rate changes during the Valsalva maneuver in patients with isolated aortic insufficiency

To determine the possible relationship between left ventricular dilatation and heart rate changes provoked by the Valsalva maneuver (Valsalva ratio), we studied 9 patients with isolated chronic aortic insufficiency. Left ventricular systolic function was assessed by two-dimensional echocardiography and cardiac catheterization. All patients were asymptomatic (functional class I of the New York Heart Association). The left ventricular internal diameters and volumes were significantly increased in all patients. The asymptomatic patients had either normal or slightly depressed ejection fraction (EF > 0.40). The Valsalva ratio of these asymptomatic patients showed no significant correlation with the left ventricular volumes or with the left ventricular ejection fraction. In other words, parasympathetic heart rate control, as expressed by the Valsalva ratio, was normal in the asymptomatic patients with left ventricular dilatation and preserved left ventricular ejection fraction. Therefore, left ventricular dilatation may not be the major mechanism responsible for the abnormal parasympathetic heart rate control of patients with acquired heart disease.

Antiarrhythmic effect of repeated coronary occlusion during balloon angioplasty

OBJECTIVES

The purpose of the present study was to assess whether brief, repeated coronary artery occlusions during balloon angioplasty protect against ischemia-induced ventricular ectopy.

BACKGROUND

Most sudden cardiac deaths are caused by fatal ventricular arrhythmias precipitated by early myocardial ischemia of acute coronary occlusion. In animals, a preceding 3- to 5-min coronary occlusion protects against malignant ventricular arrhythmias during a subsequent prolonged coronary occlusion. Whether such an antiarrhythmic effect caused by ischemic preconditioning occurs in humans is not known.

METHODS

To assess the effects of a preceding, brief vessel occlusion-reperfusion cycle on the occurrence of ventricular ectopy, continuous electrocardiographic, heart rate and blood pressure recordings were performed in 156 patients before and during two identical balloon occlusions of a coronary artery (mean 111 s) separated by a 5-min equilibration period.

RESULTS

The occluded vessel was the left anterior descending coronary artery in 94 patients, the left circumflex branch in 29 patients and the right coronary artery in 33 patients. Balloon occlusion of a coronary artery caused ventricular ectopy in 24 patients. The incidence of ventricular ectopy was higher during the first occlusion than during the second occlusion (21 patients [13.5%] vs. 11 patients [7%], p = 0.02). In 13 patients, ventricular ectopy was observed only during the first occlusion; in 8 patients during both occlusions; and in 3 patients only during the second occlusion. Bigeminal or repetitive ectopic beats were observed in eight patients during the first coronary occlusion and in four patients during the second occlusion. Atrial premature beats occurred during the first occlusion in three patients, but in none of the patients during the second occlusion. The 24 patients with ventricular ectopy during coronary occlusion had milder stenosis than the rest of the patients (mean [+/- SD] 74 +/- 12% vs. 81 +/- 12%, p = 0.01). The 13 patients with ventricular ectopy only during the first occlusion did not, however, differ significantly with respect to any clinical or angiographic features from the rest of the patients with ventricular ectopy. There were no significant differences in the signs of myocardial ischemia or hemodynamic variables between the sequential occlusions.

CONCLUSIONS

A preceding, short vessel occlusion-reperfusion cycle seems to increase the electrical stability of ischemic myocardium.