Collateral function in chronic total coronary occlusions is related to regional myocardial function and duration of occlusion

BACKGROUND

Collateral circulation can maintain myocardial function and viability in chronic total coronary occlusion (TCO). The present study evaluates the relation of myocardial function and duration of occlusion to collateral function.

METHODS AND RESULTS

A total of 50 patients underwent a successful recanalization of a TCO (>4 weeks' duration). Collateral function was assessed by intracoronary Doppler and pressure recordings before the first balloon inflation and after PTCA had been completed. Collateral function was assessed by Doppler- (CFI(D)) and pressure-derived collateral flow indices (CFI(P)), as well as indices of collateral (R(Coll)) and peripheral resistance (R(P)). Patients with normokinesia had lower R(Coll) (4.9+/-2.5 versus 11.8+/-8.2 mm Hg. cm(-1). s(-1); P=0.033) and lower R(P) (3.8+/-1.9 versus 6.1+/-4.1 mm Hg. cm(-1). s(-1); P=0.031) than those with akinesia. Patients with akinesia and a TCO duration of </=3 months had the highest R(Coll) and R(P), whereas those with akinesia and a longer TCO duration had similar collateral function as patients with normokinesia. After PTCA, CFI(D) and CFI(P) decreased from 0.37+/-0.20 to 0.21+/-0.17 (P<0.001) and from 0.44+/-0.12 to 0.36+/-0.11 (P<0.001), respectively, with an increase in R(Coll) of 139+/-128% (P<0.001) and R(P) by 65+/-99% (P=0.003). This attenuation of collateral function was less pronounced with epicardial collaterals than with intramyocardial collaterals.

CONCLUSIONS

Collateral function was better in patients with TCO and normal regional function than in those with impaired regional function. In the latter group, collateral function improvement was time dependent. After recanalization, the recruitable collateral function was attenuated because of an increase of R(Coll) and R(P).

Reversibility of coronary endothelial vasomotor dysfunction in idiopathic dilated cardiomyopathy: acute effects of vitamin C

In patients with idiopathic dilated cardiomyopathy, endothelium vasomotor function is disturbed. Increased oxidative stress and the consecutive formation of oxygen free radicals have been implicated as one possibility for this observation, suggesting that nitric oxide (NO) is inactivated by oxygen free radicals. We tested the hypothesis that the antioxidant, vitamin C, may improve endothelial function in idiopathic dilated cardiomyopathy. In 11 patients, the endothelium-dependent vasomotor response of the left anterior descending coronary artery to intracoronary acetylcholine (ACh) infusion (1/2 x 10(-6) mol/L, 1/4 x 10(-5) mol/L; respectively) was determined before and immediately after intravenous infusion of 3 g of vitamin C. Coronary cross-sectional diameter was obtained by quantitative coronary angiography, average peak velocity was measured by an intracoronary Doppler flow wire, and coronary blood flow (CBF) was calculated. Maximum cross-sectional diameter was determined after administration of nitroglycerin. Dose-dependent ACh showed a decrease in cross-sectional diameter (-5% to -7%, p <0.05) and an increase in average peak velocity (+16% to +25%, p <0.05); the CBF was unchanged (+1% to -2%, p = NS). After vitamin C infusion, the cross-sectional diameter increased in a dose-dependent manner from +11% to +15%, the average peak velocity increased from +20% to + 41% (p <0.05), and the CBF increased from +38% to + 82% (p <0.01, p <0.001, respectively). Thus, patients with idiopathic dilated cardiomyopathy had endothelial dysfunction, and administration of vitamin C reversed endothelium-dependent dysfunction.

[ Update 2001. Myocarditis--cardiomyopathy]

Myocarditis is a common cardiological disease. New molecular biological and immunohistological methods have confirmed the persistence of viral infection and chronic myocardial inflammation in a considerable number of patients. A causal link between viral myocarditis and the development of dilated cardiomyopathy has been recognized. This has prognostic implications and helps for the decision of a specific immunosuppressive, immunomodulatory and antiviral therapy.

Randomized comparison of coronary stent implantation under ultrasound or angiographic guidance to reduce stent restenosis (OPTICUS Study)

BACKGROUND

Observational studies in selected patients have shown remarkably low restenosis rates after ultrasound-guided stent implantation. However, it is unknown whether this implantation strategy improves long-term angiographic and clinical outcome in routine clinical practice. Methods and Results-- A total of 550 patients with a symptomatic coronary lesion or silent ischemia were randomly assigned to either ultrasound-guided or angiography-guided implantation of </=2 tubular stents. The primary end points were angiographic dichotomous restenosis rate, minimal lumen diameter, and percent diameter stenosis after 6 months as determined by quantitative coronary angiography. Secondary end points were the occurrence rates of major adverse cardiac events (death, myocardial infarction, coronary bypass surgery, and repeat percutaneous intervention) after 6 and 12 months of follow-up. At 6 months, repeat angiography revealed no significant differences between the groups with ultrasound- or angiography-guided stent implantation with respect to dichotomous restenosis rate (24.5% versus 22.8%, P=0.68), minimal lumen diameter (1.95+/-0.72 mm versus 1.91+/-0.68 mm, P=0.52), and percent diameter stenosis (34.8+/-20.6% versus 36.8+/-19.6%, P=0.29), respectively. At 12 months, neither major adverse cardiac events (relative risk, 1.07; 95% CI 0.75 to 1.52; P=0.71) nor repeat percutaneous interventions (relative risk 1.04; 95% CI 0.64 to 1.67; P=0.87) were reduced in the ultrasound-guided group.

CONCLUSIONS

This study does not support the routine use of ultrasound guidance for coronary stenting. Angiography-guided optimization of tubular stents can be performed with comparable angiographic and clinical long-term results.

Microvascular dysfunction in chronic total coronary occlusions

BACKGROUND

Microvascular dysfunction is defined as reduced coronary flow reserve in the absence of an epicardial stenosis. This study determined its prevalence and relation to regional myocardial function in chronic total coronary occlusions (TCO).

METHODS AND RESULTS

After recanalization and stenting of a TCO (duration, >4 weeks) in 42 patients, coronary flow velocity reserve (CFVR) was measured by intracoronary Doppler. In a subset of 27 patients, intracoronary pressure was recorded to obtain the fractional flow reserve (FFR). In 21 patients, the CFVR was reassessed after 24 hours. CFVR was <2.0 in 55% of all patients. In the subgroup with simultaneous pressure recordings, 52% of patients showed a CFVR<2.0 and a FFR>/=0.75, indicating microvascular dysfunction. Both reduced CFVR and reduced FFR occurred in only 2 patients (7.7%). CFVR and FFR were not correlated (r=0.03). A low CFVR was associated with a higher baseline average peak velocity (35.6+/-16.6 versus 22.4+/-11.5 cm/s; P=0.006). Doppler parameters did not change within 24 hours. Regional dysfunction had no influence on CFVR. Patients with diabetes and/or hypertension had a lower CFVR than those without this comorbidity (1.86+/-0.69 versus 2.36+/-0.45; P<0.05).

CONCLUSIONS

Microvascular dysfunction was observed in 55% of TCOs, independent of the impairment of regional myocardial function. Dysfunction was observed more often in patients with diabetes and hypertension. Neither CFVR or FFR alone is appropriate for assessing angioplasty results in patients with a TCO; CFVR should be combined with FFR to differentiate microvascular dysfunction from residual coronary stenosis or diffuse disease.

Localization of late potential sources in myocardial infarction

INTRODUCTION

Late potentials (LP) are markers of arrhythmogenic events after myocardial infarction (MI). The localization of LP sources would help to identify arrhythmogenic myocardium. The purpose of this study was to localize these LP sources from non-invasive body surface mapping data.

METHODS AND RESULTS

Six patients were investigated with cardiac MRI and signal averaged 62-lead magnetocardiography after MI. Three of them were suffering from sustained ventricular tachycardia (VT). Sophisticated computer algorithms were used in order to compute the current density on the surface of the left ventricle. We compared these current density distributions for the entire QRS complex and the high frequency LP signals. In the three patients which had premature ventricular complexes (PVCs) we localized the exit sites of these arrhythmias. We found a close matching of the low current density areas based on the QRS complexes and the high current density areas based on the LP signals. These areas predominantly corresponded to sites of the infarctions. Exit sites of PVCs were located close to these areas.

CONCLUSIONS

By means of sophisticated computer algorithms we were able to localize LP sources. This would be useful in steering catheter ablation and coronary revascularization therapies. However, the method has to be proven with the help of invasive mapping in a larger number of patients.

Reproducibility of HTS-SQUID magnetocardiography in an unshielded clinical environment

A new technology has been developed which measures the magnetic field of the human heart (magnetocardiogram, MCG) by using high temperature superconducting (HTS) sensors. These sensors can be operated at the temperature of liquid nitrogen without electromagnetic shielding. We tested the reproducibility of HTS-MCG measurements in healthy volunteers. Unshielded HTS-MCG measurements were performed in 18 healthy volunteers in left precordial position in two separate sessions in a clinical environment. The heart cycles of 10 min were averaged, smoothed, the baselines were adjusted, and the data were standardized to the respective areas under the curves (AUC) of the absolute values of the QRST amplitudes. The QRS complexes and the ST-T intervals were used to assess the reproducibility of the two measurements. Ratios (R(QRS), R(STT)) were calculated by dividing the AUC of the first measurement by the ones of the second measurement. The linear correlation coefficients (CORR(QRS), CORR(STT)) of the time intervals of the two measurements were calculated, too. The HTS-MCG signal was completely concealed by the high noise level in the raw data. The averaging and smoothing algorithms unmasked the QRS complex and the ST segment. A high reproducibility was found for the QRS complex (R(QRS)=1.2+/-0.3, CORR(QRS)=0.96+/-0.06). Similarly to the shape of the ECG it was characterized by three bends, the Q, R, and S waves. In the ST-T interval, the reproducibility was considerably lower (R(STT)=0.9+/-0.2, CORR(STT)=0.66+/-0.28). In contrast to the shape of the ECG, a baseline deflection after the T wave which may belong to U wave activity was found in a number of volunteers. HTS-MCG devices can be operated in a clinical environment without shielding. Whereas the reproducibility was found to be high for the depolarization interval, it was considerably lower for the ST segment and for the T wave. Therefore, before clinically applying HTS-MCG systems to the detection of repolarization abnormalities in acute coronary syndromes, further technical development of the systems is necessary to improve the signal-to-noise ratio.

Cardiac troponins have no prognostic value for acute and chronic cardiac events in asymptomatic patients with end-stage renal failure

BACKGROUND

Cardiovascular diseases determine overall mortality in patients with end-stage renal failure. Therefore, testing for myocardial ischemia is important. Elevation of cardio-specific troponins have been frequently measured in patients with end-stage renal failure. Thus, we studied systematically whether patients on chronic intermittent hemodialysis without overt coronary heart disease have increased serum levels of cardiac troponin T and cardiac troponin I. After 2 years, the patients were screened again for cardiac events.

METHODS AND RESULTS

The patients had no history of angina during the previous 3 months or myocardial infarction (MI) within the previous 2 years. For analysis we used two cardio-specific assays for troponin T as well as for troponin I and compared the results with the CK-MB concentration. In a number of patients serum concentrations were elevated above the reference range as follows: troponin T rapid bedside assay: 41 of 100 patients, troponin I rapid bedside assay: 27 of 100 patients, quantitative measurement oftroponin T: 22 of 100 patients, quantitative measurement oftroponin I: 7 of 100 patients, CK-MB: 2 of 100 patients. The increased serum levels of cardiac troponins were neither the result of uremic perimyocarditis (pericardial effusion), changes in the hemodialysis regimen, pulmonary congestion nor were they consistent with the etiology of renal failure. None of the patients with an elevated troponin level in either of the test suffered from any acute cardiac event initially. Within 2 years 18 of 100 patients died, 13 out of them because of cardiac events. Fourteen patients had a myocardial infarction and 19 patients developed angina pectoris. Sensitivity and specificity (0.75 and 0.67) of troponin T rapid bedside assay for MACE (angina pectoris, MI, cardiac death) was lower compared to studies in patients with normal renal function. Correlation between troponin elevation and late outcome was low or absent.

CONCLUSION

Patients on chronic intermittent hemodialysis frequently present with elevated TnT and TnI levels which cannot be used as predictors of acute and chronic cardiac events. Rapid bedside assays have a lower specificity than quantitative assays.

Increase of serum estradiol in cirrhotic men treated by transjugular intrahepatic portosystemic stent shunt

BACKGROUND/AIMS

Liver cirrhosis is frequently associated with sexual dysfunction and hormonal abnormalities. To evaluate the effect of portosystemic shunting on sex steroid serum concentrations, a prospective study was performed in cirrhotic patients treated consecutively and electively by transjugular intrahepatic portosystemic stent shunt (TIPS).

METHODS

In 27 patients with liver cirrhosis we measured serum levels of testosterone (T), sexual hormone binding globulin (SHBG), luteinizing hormone, follicle-stimulating hormone, dehydroepiandrosterone sulfate, androstenedione (A), estradiol (E2), 17-OH-progesterone and the T/SHBG ratio before and 3 months after TIPS.

RESULTS

In men (n = 17) 3 months after TIPS, A and E2 significantly increased, with mean serum levels rising from 4.4 +/- 2.5 to 5.6 +/- 2.9 ng/ml (P = 0.04) and from 27 +/- 9 to 40 +/- 19 pg/ml (P = 0.003), respectively. In contrast to A the increase of E2 persisted at 9 and 15 months after TIPS. Erectile dysfunction increased from 30% before TIPS to 70% after TIPS. In women (n = 10) A and E2 levels did not change significantly after TIPS.

CONCLUSIONS

TIPS aggravated hormonal dysbalance of sex steroids in favor of estrogens (hyperestrogenism) in men.

Methods for the computational localization of atrio-ventricular pre-excitation syndromes

BACKGROUND

The site of atrioventricular pre-excitation can roughly be estimated with the help of schemes basing on a few number of electrocardiogram (ECG) leads. Computer algorithms have been developed which utilize the body surface mapping of the pre-excitation signal for the localization purpose. We tested several new algorithms.

METHOD

A patient suffering from Wolff-Parkinson-White syndrome was investigated prior the catheter ablation. The body surface mapping was performed with a 62-lead magnetocardiograph. The site of pre-excitation was calculated by using different methods: the dipole method with fixed and moving dipoles, the dipole scan on the endocardium, and different current density methods (L1 norm method, L2 norm method, low resolution electromagnetic tomography (LORETA) method, and maximum entropy method). Three-dimensional (3D) magnetic resonance imagings (MRIs) of the heart were used to visualize the results. The source positions were compared to the site of catheter ablation.

RESULTS

The accessory pathway was successfully ablated left laterally. This site was correctly identified by the conventional dipole method. By scanning the entire endocardial surface of the heart with the dipole method we found a circumscribed source area. This area too, was located at the lateral segment of the atrio-ventricular grove. The current density methods performed differently. Whereas the L1 norm identified the site of pre-excitation, the L2 norm, the LORETA method and the maximum entropy method resulted in extended source areas and therefore were not suited for the localization purpose.

CONCLUSION

The dipole scan and the L1 norm current density method seem to be useful additions in the computational localization of pre-excitation syndromes. In our single case study they confirmed the localization results obtained with the dipole method, and they estimated the size of the suspected source region.

[Leptin: a parameter for metabolic changes in heart failure]

OBJECTIVE

Advanced chronic heart failure is a hypercatabolic state with an imbalance between anabolic and catabolic metabolism and finally progressive loss of both muscle mass and adipose tissue. Leptin, the product of the obesity gene, is a hormone secreted by adipocytes. Therefore, we tested the hypothesis that plasma leptin concentrations are reduced in advanced chronic heart failure.

METHODS

In 20 patients with chronic congestive heart failure (LVEF 23 +/- 6%) and 20 healthy controls (LVEF 65 +/- 8%) matched for gender, age, and body mass index, fasting plasma leptin (ELISA) and TNF alpha (ELISA) were measured. Follow-up examination was performed after 1 year.

RESULTS

The fasting plasma leptin concentrations of patients with NYHA grade III (8.4 +/- 3.8 ng/ml*) and NYHA grade IV (4.6 +/- 2.4 ng/ml dagger) were significantly lower as compared with the controls (11.2 +/- 3.1 ng/ml; *p < 0.05, dagger p < 0.01). In patients with NYHA grade II plasma leptin levels were significantly elevated as compared with the healthy controls (14.9 +/- 4.2 ng/ml). TNF alpha was higher in heart failure patients than in healthy controls (8.6 +/- 3.6 pg/ml; 5.9 +/- 2.1 pg/ml; respectively; p < 0.05), but did not correlate with the NYHA functional class. Mortality of the controls was 0%, whereas 15% (n = 3) in the congestive heart failure group; one patient (5%) needs an urgent heart transplantation. All of those patients had leptin concentrations below 5 ng/ml.

CONCLUSIONS

Plasma leptin concentrations correlate with the NYHA functional class suggesting anabolic metabolism in NYHA class II and catabolic metabolism in advanced heart failure which might be of prognostic relevance.

Recovery of the cardiac adrenergic nervous system after long-term beta-blocker therapy in idiopathic dilated cardiomyopathy: assessment by increase in myocardial 123I-metaiodobenzylguanidine uptake

In chronic heart failure, elevated plasma norepinephrine (NE) levels and a disparity between the neuronal release and the effective reuptake of NE lead to an increased concentration of NE in the presynaptic cleft, causing a downregulation of the myocardial beta-adrenoceptors. The clinical and prognostic effectiveness of beta-blocker therapy has been shown in patients with chronic heart failure in several large trials. The purpose of this study was to investigate the effect of long-term beta-blocker therapy on the cardiac adrenergic nervous system as assessed by the myocardial uptake of 123I-metaiodobenzylguanidine (MIBG), an analog of NE, in idiopathic dilated cardiomyopathy (IDC).

METHODS

In 10 patients with IDC and stable chronic heart failure the myocardial MIBG uptake was measured at baseline and at 1 y (median, 11.5 mo) after treatment with beta-blockers (metoprolol, n = 5; bisoprolol, n = 1; and carvedilol, n = 4) in addition to standard medication. In parallel with the changes in MIBG uptake, the New York Heart Association functional class, the left ventricular ejection fraction (LVEF), and the left ventricular end-diastolic diameter (LVEDD) were documented before and after 1 y of therapy with beta-blockers.

RESULTS

During the 1-y follow-up, a significant increase in myocardial 123I-MIBG uptake (P = 0.005) in parallel with an improved LVEF (P = 0.005) and a reduced LVEDD (P = 0.019) was found. A trend toward an improvement of the New York Heart Association functional class under the beta-blocker therapy (P = 0.139) was also found.

CONCLUSION

Assessment of the myocardial 123I-MIBG uptake is a useful noninvasive tool for evaluating changes in cardiac sympathetic nerve activity under medical therapy. Long-term treatment with beta-blockers in IDC causes a recovery of the cardiac adrenergic nervous system concomitantly with a clinical and hemodynamic improvement.

Immediate changes of collateral function after successful recanalization of chronic total coronary occlusions

BACKGROUND

Coronary collaterals are essential to maintain myocardial function in chronic total coronary occlusions (TCOs). The aim of the present study was to assess the collateral circulation in TCOs before coronary angioplasty and to determine the recruitable collateral perfusion after recanalization by use of intracoronary Doppler flow velocimetry.

METHODS AND RESULTS

In 21 patients with TCOs (duration >4 weeks), Doppler recordings of basal collateral flow were obtained before the first balloon inflation. Angioplasty was performed with stent implantation in all lesions. At the end of the procedure, recruitable collateral flow was measured during a repeat balloon inflation. The collateral flow index (CFI) was calculated from the velocity integral during the occlusion/velocity integral of antegrade flow. In 17 of 21 patients, angiography was repeated after 24 hours, and CFI was reassessed. Average peak velocity of collateral flow was 10.9+/-5.6 cm/s with a predominantly systolic flow (diastolic/systolic velocity ratio <0.5) compared with antegrade flow (diastolic/systolic velocity ratio >1.5). After recanalization, the average peak velocity of recruitable collateral flow dropped by >50% to 4.7+/-2.5 cm/s. CFI fell from 0.48+/-0.25 to 0.21+/-0.16 (P:<0.001). There was no further change of CFI during the following 24 hours. CFI was higher in patients with preserved regional ventricular function than in those with akinetic myocardium (0.57+/-0.23 versus 0.38+/-0.12, P:<0.05).

CONCLUSIONS

Collateral circulation in TCO provided 50% of antegrade coronary flow. A considerable fraction of collateral flow was immediately lost after recanalization, indicating that TCO may not remain protected from future ischemic events by a well-developed collateral function.

Non-surgical extraction of right cardiac "thrombus in transit"

In two hemodynamically unstable patients, massive pulmonary embolism and free-floating right cardiac thrombi were diagnosed. Thrombolytic therapy was contraindicated and surgical treatment was rejected. In these two cases, we describe a successful non-surgical, percutaneous extraction of mobile right cardiac thrombi. Cathet. Cardiovasc. Intervent. 51:316-319, 2000.

[Acute acral ischemia in all fingers possibly due to a Borrelia infection]

Acute interruption of circulation in the distal fingers can be both expression of an embolic event as well as the first manifestation of a vasculitis or collagenosis. The search for its cause is frequently difficult. In many cases a specialized analysis of the coagulation system as well as diagnostics such as ultrasound scan of the heart or a systematic antibody scanning do not reveal the origin of an embolus or the underlying disorder. On the basis of a case-report we would like to focus on a possible context between an infection of Borrelias stage III and consecutive deterioration of peripheral arterial perfusion in the fingers. Besides Jo-1- and positive sceleton-muscle-antibodies there were no serological and clinical indications for an autoimmune disease. It was possible to avoid acral necrosis by means of an antibiotic, immunosuppressive and rheological therapeutic concept. We recommend to control the borellia-antibody-level in cases of obscure threatening peripheral necrosis caused by arterial perfusion stop.

Temporal properties of high frequency intra-QRS signals in myocardial infarction and healthy hearts

The prevalence of late potentials after myocardial infarction depends on the site of the infarction. This may be caused by the different activation onsets of the anterior and inferior myocardial segments. Therefore, in anterior infarcts the high frequency signals may be concealed within the QRS whereas in the inferior infarcts they last beyond the end of the QRS. We compared the timing and the spatial patterns of high frequency intra-QRS signals (IQSs) in the different infarction sites. We investigated 14 patients with anterior infarcts, 17 patients with inferior infarcts, and 10 healthy subjects. 31-lead magnetocardiograms were recorded in left precordial position and averaged. The QRS signals were smoothed with a Savitzky-Golay filter. The smoothed QRS signals were subtracted from the measured ones. The difference of the signals (frequency band of about 60-200 Hz) representing the high frequency components was quantified. The percentage of the high frequency signals was calculated for the entire QRS, for the first and for the second half, respectively. We found that in patients with anterior infarcts the high frequency components predominantly appeared in the first half of the QRS whereas in inferior infarcts these components predominantly appeared in the second half of the QRS. The different infarction sites were associated with different spatial patterns of the high frequency signals on the body surface. In healthy subjects there was not such a preferential association of time intervals and high frequency signals. Late potentials are the special case of high frequency signals appearing in the terminal QRS. It is the general property of the myocardium to generate high frequency signals associated with the depolarization of infarcted tissue. The timing of such signals and the spatial distribution patterns on the body surface may help to identify the location of the sources.

Tumour necrosis factor-alpha expression in idiopathic dilated cardiomyopathy: correlation to myocardial inflammatory activity

High numbers of inflammatory cells are found in a subgroup of patients with idiopathic dilated cardiomyopathy (IDCM). We hypothesized that the extent of inflammation is linked to myocardial TNF-alpha expression in human IDCM. Fourteen patients who consecutively underwent endomyocardial biopsy (EMB) were stratified into two groups-a group with low and a group with high myocardial inflammatory index (MII)-based on immunohistochemical analysis of cellular infiltration and HLA I and II expression. Myocardial TNF-alpha messenger RNA (mRNA) expression was determined by reverse transcriptase polymerase chain reaction, TNF-alpha protein was localized by immunohistochemistry and TNF-alpha serum levels were measured by EIA. IDCM patients with a high MII (n=6) showed a 1. 9-fold higher TNF-alpha mRNA expression when compared to IDCM patients with low MII (n=8, P=0.020). TNF-alpha protein was detected at perinuclear regions of cardiac myocytes and the endothelium. TNF-alpha serum levels were 3.0 (0.55) pg/ml in patients with high MII compared to 1.35 (0.20) pg/ml in patients with low MII (P=0.017). According to immunolocalization cardiac myocytes and the endothelium seem to be the major source of TNF-alpha production. Whether the elevated systemic level of TNF-alpha found in patients with high MII are elaborated by the myocardium or are produced by other tissues representing a general immune activation is not clear.

Early time course of heart rate variability after thrombolytic and delayed interventional therapy for acute myocardial infarction

In 89 of 97 consecutive patients with myocardial infarction (MI) undergoing thrombolysis and delayed early coronary angiography with PTCA, if indicated, heart rate variability (HRV) in time domain was evaluable 40 +/- 11 h after the onset of chest pain using 24-hour ECG recordings. Patients with anterior MI (n = 40) had lower values for HRV and left ventricular ejection fraction (p < 0.05). The mean of all 5-min standard deviations of RR intervals (SDNNi) and the root-mean-square difference of successive RR intervals (rMSSD) decreased significantly (p < 0.001 each), whereas the standard deviation of all normal RR intervals and the percentage of absolute differences between successive RR intervals only showed a tendency to lower values 4 weeks after MI (p = 0.20 and 0.08, respectively). The decreases in SDNNi and rMSSD were more evident in inferior than in anterior MI. The time course of HRV following MI was similar in patients with and without PTCA. These results indicate an initial vagal hyperactivity in inferior MI, which is quickly predominated by sympathetic activation and a prolonged recovery of the cardiac autonomic imbalance after MI despite a successful combined reperfusion therapy.

[Cardiorespiratory desynchronization after acute myocardial infarct]

The prognosis of cardiac diseases can be estimated from the variability of regulation parameters of the cardiovascular system. Changes in the variability of a regulation parameter causes disturbances in the synchronisation of interacting control loops. Conclusions about the severity of the underlying functional impairment can be drawn from these disturbances. This study investigates the synchronisation of the control loops of the heart rate and respiration (cardiorespiratory synchronisation, CRS) after acute myocardial infarction. We investigated 43 patients after myocardial infarction and 27 healthy controls. To quantify the CRS the synchronisation in phase of respiration and heart rate was assessed. The heart rate variability (HRV) was also assessed. Patients after myocardial infarction have a significantly reduced HRV and CRS. There is a non-linear relationship between HRV and CRS. Patients with left ventricular enlargement and reduced left ventricular ejection fraction (< or = 45%) significantly differed from the other infarct patients and controls in CRS but not in HRV. They had a marked degree of cardiorespiratory desynchronisation and were identified by a threshold value. CRS is a measure of the interaction of respiration control and heart rate control. After myocardial infarction, a reduction of the HRV can be observed. The desynchronisation of the control loops of respiration and heart rate especially appears in large infarcts. This can be quantitatively assessed by the method presented.

[Effect of choice of baseline correction interval on localization of electrical heart activity]

The electric heart activity can be localised from body surface mapping data with computer algorithms. At higher heart rates the T and P waves merge. Thus, the offset can not be subtracted in the TP segment. We investigated 28 healthy volunteers with signal averaged 31-lead magnetocardiography. The offset of the baseline was determined in the TP-segment and in the PR-segment, respectively. The electrical heart activity was localised in the initial 30 ms of the QRS complex (Q), at the QRS maximum (R), and at the T wave maximum (T). The volume currents were considered by using a boundary element model with the compartments lungs and torso. The 3D positions of the dipoles, the dipole orientations, and the dipole strengths were calculated using the data preprocessed with two different offset correction intervals. The offsets of the TP and PR segments significantly differed one from another. The average deviations of the dipole localisation were within a few centimetres (Q: 20 +/- 31 mm, R: 6 +/- 13 mm, T: 14 +/- 30 mm). However, in a small number of subjects (Q: n = 5, R: n = 2, T: n = 5) we observed a deviation of more than 30 mm. These deviations were not linearly correlated to the differences in the baseline offsets. High resolution recordings continuously detect heart activity in the PR segment. The correction of the baseline in the PR segment instead of the TP segment may introduce artefacts in the source localisation and therefore should be avoided.

Lack of association between 27-bp repeat polymorphism in intron 4 of the endothelial nitric oxide synthase gene and the risk of coronary artery disease

The gene encoding endothelial nitric oxide synthase (ecNOS) is a candidate gene for the mediation of initial endothelial cell damage seen in arteriosclerosis. Although the association of ecNOS polymorphisms with hypertension has been studied extensively, there is little information regarding its association with coronary artery disease (CAD). We decided to study a 27 base-pair tandem repeat polymorphism in intron 4 of the ecNOS gene in 1043 individuals (413 controls, 630 patients with CAD) who consecutively underwent coronary angiography at our institution. The frequencies of the genotypes drawn from 1038 individuals were 0.69, 0.28 and 0.03 in the controls and 0.73, 0.25 and 0.02 in individulas with CAD for the ecNOS4b/b, ecNOS4b/a and ecNOS4a/a genotypes, respectively (p = n.s). There was no shift of the genotype frequencies from the expected distribution based on the Hardy-Weinberg equilibrium. Neither the rare ecNOS4a allele nor the ecNOS4a/a genotype conferred an independent risk factor for CAD in subgroups, e.g. smokers, diabetic individuals, hypertensive individuals and individuals with a low conventional risk for CAD. In five individuals we identified an additional 27-bp repeat in the ecNOS gene (ecNOS4c), which occurred heterozygous with the ecNOS4b allele (ecNOS4b/c genotype). In conclusion, the ecNOS4a allele as well as the ecNOS4a/a genotype did not show a general association with CAD in the studied European population. Even in high-risk subgroups the ecNOS4a/4a genotype did not represent an independent risk factor for CAD. In addition, the severity of CAD was not associated with the ecNOS4a allele/ecNOS4a/a genotype.

Zur Makro- und Mikrozirkulation am Vorfuß unter verschiedenen Kompressionsdrücken bei gesunden Probandinnen

Zielstellung und Methoden: Das Ziel dieser Studie bestand in der Untersuchung der Makro- und Mikrozirkulation am Fuß bei Gesunden unter dosierter Kompression des Beines. Die Makro- und Mikrozirkulation wurden mit Doppler-Ultraschall-Knöchelarteriendruck- Messung und Nahe-Infrarot-Rot-Remissions-Photoplethysmographie (NIRP) bzw. mit Laser-Doppler-Flowmetrie (LDF), transkutaner Sauerstoff- (tcpO2) bzw. Kohlendioxidpartialdruckmessung (tcpCO2) und NIRP an 13 weiblichen Probanden, mittleres Alter 33,4 ± 16,8 Jahre, unter Ruhebedingungen vor und nach jeweils 5-minütiger Kompression mit 10, 20, 30, 40 bzw. 50 Torr gemessen. Ergebnisse: Der Knöchelarteriendruck sowie tcpO2 und tcpCO2 blieben unverändert. Ein signifikanter Abfall zeigte sich mit steigendem Kompressionsdruck oberhalb 20 Torr beim LDF-Flux (p <0,01) und Hämatokrit (p <0,05). Der mit NIRP bestimmte periphere Mikrozirkulations- Koeffizient pMC verminderte sich signifikant (p <0,05) oberhalb 10 Torr Kompressionsdruck. Die spektrale Maßzahl MLFo veränderte sich kaum, während die Maßzahl MLFv signifikant (p <0,05 bzw. 0,01) anstieg. Der Pulsquotient PQ fiel signifikant (p <0,05) ab bei signifikanten (p <0,01) Rückgang von Gipfelzeit TG und Wendepunktzeit TW oberhalb von 10 bzw. 30 Torr. Schlußfolgerung: Bei Gesunden tritt unter Kompression bis 50 Torr keine Verschlechterung der Makrozirkulation auf, während sich die Mikrozirkulation komperessionsbedingt ändert.