Optimal Values for the Parameters of an On-line Algorithm Monitoring the QRS Waveform

Digital “on-line” QRS detection and classification in monitoring units is often performed by an algorithm using the ECG spatial velocity. Our study was undertaken to provide as well as to justify the choice of the value given to each parameter of such an algorithm (Gerlings et al., Comput. biomed. Res.5: 14—24, 1972). It was made on 5-minute ECG recordings sampled from a single lead on 17 patients. The following parameters were studied and their error function (QRS not detected, badly classified, and detected but non-existent) thoroughly investigated. For the QRS detection which was based on three parameters, para WD (window of derivative), para TD (threshold of derivative) and para TP (threshold of sampled points), the choice of WD at 24 ms was found to be critical and provided the optimal detection at 96.9%. For the QRS classification only para TolP (tolerance of sampled points)was shown to be important; when set at .5 para TolP gave the optimal classification at 97%. The method can also be used to investigate the response of the algorithm to particular QRS and to propose for such cases a specific and optimal value for each parameter.

Analyses of DNA adducts formed by ochratoxin A and aristolochic acid in patients with Chinese herbs nephropathy

Chinese herbs nephropathy (CHN), a unique type of nephropathy has been associated with the intake of weight-reducing pills containing the Chinese herb Aristolochia fangchi. Moreover, an association between the use of A. fangchi and urothelial cancer in CHN patients has been reported indicating that aristolochic acid (AA) the major alkaloid of A. fangchi might be the causal agent. Similarities of CHN to the Balkan endemic nephropathy (BEN) have led to the hypothesis of a common etiological agent for both diseases. Evidence has accumulated that BEN is an environmentally-induced disease strongly associated with the fungal mycotoxin ochratoxin A (OTA). Both, AA and OTA are nephrotoxic and carcinogenic and induce the formation of DNA adducts. As OTA has been suspected as fungal contaminant in the herbal batches used for the preparation of the weight-reducing pills we analysed tissues from CHN patients by the 32P-postlabeling procedure for the presence of DNA adducts related to both OTA and AA exposure. Whereas, AA-specific DNA adducts were detected in all five urinary tract tissues from five patients (total RAL: 32-251 adducts per 10(9) nucleotides), OTA-related DNA adducts were detectable in two kidneys and one ureter only (total RAL: 1.5-3.7 adducts per 10(9) nucleotides). Thus, OTA-related DNA adduct levels were about 50 times lower than AA-DNA adduct levels. In female and male rats that were treated with the slimming regimen in the same way like the CHN patients except that the amount of Chinese herbs was 10 times higher, AA-DNA adducts were found in kidney tissues (total RAL ranging from 51 to 83 adducts per 10(9) nucleotides) but adducts derived from OTA were not observed. These results demonstrate that OTA-related DNA adducts do not play a key role in CHN or CHN-associated urothelial cancer.

Effects of spironolactone-altizide on left ventricular hypertrophy

OBJECTIVE

To investigate the effects of the association spironolactone (25 mg)/altizide (15 mg) as monotherapy on left ventricular hypertrophy (LVH) in patients with mild to moderate hypertension. Additionally, to study the correlation between left ventricular mass (LVM) index and electrocardiographic (ECG) criteria for LVH.

METHODS AND RESULTS

This was an open, prospective study of 6 months. Patients with mild to moderate essential hypertension were treated with spironolactone/altizide for two months and were included in the study if their blood pressure (BP) at the end of this first treatment period was normalised according to protocol criteria (systolic BP < 160 mm Hg and diastolic BP < 95 mm Hg). Patients then entered a second 4-month treatment period. LVM was determined by echocardiography performed at the beginning of treatment and after 6 months. LVH was defined as LVM > or = 100 g/m2 in women and LVM > or = 131 g/m2 in men. Echocardiograms were interpreted blindly by two echocardiography reading laboratories. Seventy-one patients with a normalised BP after two months of treatment, were enrolled in the study. Changes in LVM index were studied in 31/71 patients with LVH (25 women and 6 men, mean LVM index +/- (SD) 119.9 +/- 16.4 g/m2 in women and 147.8 +/- 10.9 g/m2 in men). Spironolactone/altizide significantly reduced LVM index by 10%, from 125.3 +/- 22.5 to 114.2 +/- 25.1 g/m2 (p < 0.005). Posterior and septal wall thickness decreased by 4% (p = 0.06) and 5% (p = 0.026), respectively. End-diastolic dimension was reduced by 3%, from 50.3 +/- 3.3 to 48.9 +/- 3.4 mm (p = 0.006). The posterior wall thickness to end-diastolic dimension ratio remained unchanged. Complete regression of LVH according to mass criteria occurred in 11 patients out of 31 (34.5%). The observed changes in ECG voltage criteria were in accordance with a decrease of LVM index.

CONCLUSION

In this open study, the potassium-sparing diuretic spironolactone/altizide decreases LVM index in hypertensive patients, who were selected for follow-up because they had echocardiographic LVH and because their BP had normalised during an initial 2-month treatment period.

Flow-induced vasomotor response to tachycardia of the human internal mammary artery and saphenous vein grafts late following bypass surgery

Increasing blood flow results in endothelium-dependent vasodilation of angiographically normal epicardial coronary arteries in humans. To compare the ability of internal mammary artery (IMA) and saphenous vein (SV) used as coronary artery bypass grafts to adapt their vasomotor tone to an increase in myocardial blood flow demand induced by tachycardia, 10 IMA and seven SV grafts were studied by quantitative angiography more than 6 months (range, 6-82 months) after surgery in 17 patients. All grafts were angiographically smooth and implanted to large nonakinetic perfusion zones. Angiograms were obtained in basal sinus rhythm (71 +/- 10 beats/min), during atrial pacing (129 +/- 9 beats/min), and after intragraft infusion of 1 mg isosorbide dinitrate (ISDN). In basal sinus rhythm, the cross-sectional area of SV was superior to that of IMA (10.7 +/- 3.6 versus 5.4 +/- 1.7 mm2; p less than 0.01). All IMA dilated during pacing (+14.8 +/- 11.5%; p less than 0.005) and a further increase in IMA cross-sectional area occurred after ISDN (+27.4 +/- 20.1% versus basal; p less than 0.005). In contrast, SV failed to dilate during pacing (+0.3 +/- 5.4%; p = NS) and after ISDN (+0.7 +/- 6.0% versus basal; p = NS). Thus, an increase in myocardial blood flow demand induced by tachycardia results in dilation of IMA but not of SV grafted on coronary vessels. The ability of the endothelium to modulate the vasomotor tone of IMA grafts in response to changes in blood flow could contribute to their excellent long-term functional results after coronary artery bypass surgery.

Asynchronous (segmental early) relaxation impairs left ventricular filling in patients with coronary artery disease and normal systolic function

Asynchronous segmental early relaxation, defined as a localized early segmental outward motion of the left ventricular endocardium during isovolumetric relaxation, has been associated with an altered left ventricular relaxation rate. To determine whether asynchronous segmental early relaxation also results in impaired left ventricular filling, early diastolic ventricular wall motion and Doppler-derived left ventricular filling indexes were examined in 25 patients with documented coronary artery disease and normal systolic function. Patients were further classified into two groups according to the presence (n = 15, group 1) or absence (n = 10, group 2) of asynchronous early relaxation at left ventriculography. A third group of 10 age-matched normal subjects served as a control group. No differences were observed between the two patient groups with coronary artery disease with respect to age, gender distribution, heart rate, left ventricular systolic and diastolic pressures or extent and severity of coronary artery disease. No differences in transmitral filling dynamics were observed between group 2 patients and age-matched control subjects. Conversely, group 1 patients had significantly lower peak early filling velocities (44 +/- 11 vs. 58 +/- 11 cm/s, p less than 0.01), larger atrial filling fraction (45 +/- 4% vs. 38 +/- 4%, p less than 0.001), lower ratio of early to late transmitral filling velocities (0.6 +/- 0.08 vs. 0.99 +/- 0.18, p less than 0.001) and a longer isovolumetric relaxation period (114 +/- 12 vs. 90 +/- 6 ms, p less than 0.001) compared with group 2 patients and control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty of coronary bifurcation stenoses: immediate and long-term results of the protecting branch technique

Percutaneous transluminal angioplasty (PTCA) of coronary stenoses involving major bifurcations carries a small but significant risk of side branch occlusion which can be avoided by simultaneously using multiple dilatation systems. Among 1,275 PTCA procedures performed between 1984 and 1988 in 1,035 consecutive patients, 42 double wire procedures were applied (4%) to protect and/or dilate major coronary side branches. A total of 80 coronary stenoses were attempted of which 76 were located on a bifurcation and 4 on other segments. In the first 11 patients (group A), 2 guiding catheters were used and PTCA of each vessel was successfully performed by means of separate double lumen over-the-wire balloon catheters. In the next 31 patients (group B), 2 guidewires were advanced through a single guiding catheter and PTCA was attempted using "Monorail" balloon catheters sequentially advanced over the wires. In group B, a successful PTCA was obtained in 29 patients (93%) but twisting of the wires hampered balloon progression in 5 cases, such that dilatation could only be performed by stepping back to a single wire technique. The procedure time in group B was significantly shorter than in group A: 144 +/- 30 versus 230 +/- 52 minutes (p = .01). Repeat angiography was performed in 35 out of 40 patients (87%) after a mean of 180 +/- 46 days following successful PTCA. Angiographic restenosis was present in 37% (24/65) of bifurcation segments which, in our experience, is not significantly different from the angiographic restenosis rate in less complex lesions (248/740; 34%; NS).(ABSTRACT TRUNCATED AT 250 WORDS)

[Electrovectorcardiographic diagnosis of left ventricular hypertrophy in complete left bundle-branch block]

Diagnosis of left ventricular hypertrophy (LVH) in the presence of complete left bundle-branch block (CLBB) is difficult. The value of several electro-vectorcardiographic criteria were studied in a series of 71 patients with CLBB analyzed by echocardiography. Thirty nine of the patients (55%) had anatomical LVH defined as being a left ventricular weight (LVW) above 316 g. Twenty five of the 71 patients (35%) had dilated cardiomyopathy (dCMP). Of the hypervoltage indices, only the sum of RV6 + SV2 and the QRS spatial maximum vector (MAXQRSxyz) showed a significant difference between the group with LVH and the group without LVH. The duration of QRS and the average vector of spatial area (AQRSxyz) also differed significantly between the two groups and showed a good correlation with LVW. Of the various criteria for LVH, the best balance between sensitivity and specificity belonged to the criteria of duration of QRS greater than 150 msec and AQRSxyz greater than 140 mV.msec, with a merit ratio of 0.44 and a diagnostic accuracy of 72 per cent. In the dCMP subgroup, all the voltage and duration indices were significantly different between the two groups. The criterion AQRSxyz greater than 135 mV.msec obtained the best diagnostic score, with a sensitivity of 94 per cent, specificity of 100 per cent, and accuracy of 96 per cent. This parameter gave the best overall expression of the combination of hypervoltage and delay in ventricular depolarization produced both by hypertrophy/ventricular dilation and conduction disturbances.

[Correlation of the vectorcardiographic, echocardiographic parameters and hemodynamics in valvular aortic stenosis]

The objective of this work was to verify the correlation between haemodynamic (KT), echocardiographic (ECHO) and vectorcardiographic (VCG) parameters in valvular aortic stenosis (VAS). The VCG was analyzed by the Louvain programme and compared with reference ECHO and KT parameters--transvalvular peak-gradient (PG), mean gradient (MG) and valvular area (AREA)--in 54 consecutive patients with isolated VAS. Of the 84 correlations studied, only three proved to be significant for linear parameters and six for angular parameters. The best correlation was observed between the azimuthal angle of the spatial area vector of the QRS loop and MG-KT (r2 = 0.36, p less than 0.01). On the other hand, there was no significant correlation between the reference parameters and the amplitude of the QRS spatial maximum vector. The conclusion was drawn that there was no linear correlation between the VCG indicators of LVH and ECHO and KT indices of severity in an unselected VAS population. Each method carries its own limitations and each must be used as a complement to other methods.

Prognostic value of symptom limited exercise testing in men with a high prevalence of coronary artery disease

In order to evaluate the independent prognostic information provided by exercise testing in populations with a high prevalence of coronary artery disease, survival rates were calculated with the life table method in 372 men, mean age 48 years, referred for coronary arteriography. The prevalence of angiographic coronary artery disease was 82%. During a mean follow-up of 29 months (1 to 8 years), 32 patients died and 27 patients had a nonfatal event (acute infarction or hospitalization for disabling angina). Both the history (presence or absence of typical angina pectoris or of a previous myocardial infarction) and the exercise test results (abnormal if angina and/or ST segment changes greater or equal to 0.1 mV occurred) had a significant prognostic value for the 5 year survival rate (P less than 0.001). In patients with a positive history, the 5 year cumulative survival rate was 76% if the exercise test was abnormal versus 94% if it was normal (P less than 0.001). The following 8 noninvasive and 2 invasive variables were submitted to a Cox regression analysis: age, typical angina pectoris, previous myocardial infarction, maximal heart rate and workload, maximal ST segment depression and elevation, angina pectoris during exercise testing, number of diseased vessels, and wall motion score on contrast ventriculography. By univariate analysis, the age and the maximal workload reached during exercise were the only noninvasive predictive variables for survival or cardiac events (P less than 0.05). By multivariate analysis, and combining all noninvasive and invasive variables, survival was predicted by the wall motion score, the presence or absence of 3 vessel disease, and age.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary cardiac liposarcoma simulating a left atrial myxoma

This paper reports the case of cardiac tumor which had been diagnosed as a left atrial myxoma but which later on was identified as being a primary cardiac liposarcoma. The clinical characteristics of cardiac liposarcomas, the problems of differential diagnosis, the prognosis and therapy are reviewed.

[Cardiac valvular surgery after 65 years of age]

252 symptomatic patients aged 65-79 underwent surgery between 1970 and 1982 for heart valve lesions. Hospital mortality was 11.8%. Analysis of the short and long term results justifies cardiac surgery in elderly patients with valve disease.

Bayesian analysis of stress thallium scintigraphy for the detection of multivessel coronary disease

This study was performed in 224 men to determine the respective contribution of history and thallium-201 stress myocardial scintigraphic imaging in the non-invasive prediction of the severity of coronary disease. Myocardial scintigraphic imaging had the better diagnostic accuracy (80%) for the detection of multivessel disease but the results emphasize the importance of the history in predicting the extent of coronary artery disease. In patients with myocardial infarction, the diagnostic accuracy of the history (80%) was similar to the diagnostic accuracy of myocardial scintigraphic imaging (79%); in the subgroup of patients with residual angina pectoris after infarction, the accuracy of the history was even greater (87%) than that of myocardial scintigraphic imaging (78%). Thus, after myocardial infarction, scintigraphy was useful only in the small subgroup of patients without residual angina pectoris when it had a diagnostic accuracy of 79%, slightly but insignificantly superior to that of the history (62%). In patients without previous myocardial infarction, but with typical angina, myocardial scintigraphy was clearly superior to the simple history (diagnostic accuracy of 78% versus 53%; P less than 0.001). In patients without myocardial infarction and with atypical angina the prevalence of multivessel disease was low (17%) and the diagnostic accuracy of history (83%) was barely different from the diagnostic accuracy of myocardial scintigraphic imaging (90%). Thus, when the likelihood of multivessel disease is very high (angina pectoris post myocardial infarction), or very low (atypical angina), the contribution of exercise testing is very limited. Important additional information is provided by maximal exercise testing and myocardial scintigraphic imaging only in the groups with an intermediate prevalence of multivessel disease, namely in the asymptomatic patients after myocardial infarction and in the patients with typical angina but no previous myocardial infarction.

Reassessment of the relation between QRS forces of the orthogonal electrocardiogram and left ventricular ejection fraction

Previous studies have demonstrated the existence of a strong positive correlation between the amplitude of QRS forces of the orthogonal electrocardiogram and the angiographically determined left ventricular ejection fraction. In a large group of patients evaluated for chest pain, we examined the relationship between the arithmetic summation of RX + RY + QZ (sigma R), the maximal and mean spatial QRS vectors and the ejection fraction (EF). In a total of 252 patients, there was a statistically significant correlation between sigma R and EF but a low correlation coefficient value (r:0.22, P less than 0.001). This relationship was essentially due to the group of patients with coronary artery disease and myocardial infarction (r:0.24, P less than 0.015) whereas there was no correlation in the group of normal subjects or in patients with coronary artery disease without myocardial infarction. In the group with myocardial infarction, a significant correlation between sigma R and EF existed only in patients with anterior myocardial infarction (r:0.41, P less than 0.025). In conclusion, both ejection fraction and amplitude of QRS forces decrease in coronary artery disease especially when an anterior myocardial infarction is present. However, despite the positive association between these angiographic and electrocardiographic indices, the low value of the correlation coefficient indicates that it is not possible to predict ejection fraction from the value of sigma R in individual patients.

Hemodynamic effects of molsidomine at rest and during submaximal and maximal exercise in patients with coronary artery disease limited by exertional angina pectoris

To analyze the mechanisms of action of molsidomine, a new antianginal drug, 10 patients with coronary artery disease and exertional angina pectoris were studied. Hemodynamic measurements were made at rest, during submaximal exercise and during angina-limited exercise before and 1 hour after intravenous administration of 2 mg of molsidomine. When angina pectoris was prevented after the drug was given (6 of 10 patients), the exercise intensity was increased until the recurrence of angina (3 patients) or until exhaustion (3 patients), and hemodynamic data were recorded at this higher exercise capacity. At rest and during submaximal exercise, molsidomine increased heart rate and decreased cardiac output and mean systemic and pulmonary arterial pressures. The prevention of angina pectoris was attended by lower mean systemic and pulmonary arterial pressures and pressure-rate product; cardiac output and heart rate were unchanged. The greater exercise capacity (+26 percent) after molsidomine was attended by increases in maximal cardiac output (+19 percent) and in arteriovenous oxygen difference (+6 percent); the maximal pressure-rate product was unchanged and systemic vascular resistance was lower. The mechanisms of action of molsidomine are very similar to those of nitrates and imply a decrease in venous and arterial tone. Molsidomine deserves further study in patients with angina or congestive heart failure.

Haemodynamics during maximal exercise after coronary bypass surgery

Fifty patients underwent an objective measurement of physical working capacity by means of a multistage test of maximally tolerated exertion before and after coronary bypass surgery; 29 patients also had haemodynamic measurements during maximal exercise before and after coronary bypass surgery. The patients were divided into 3 groups according to the degree of revascularisation: adequate (n = 20), partial (n = 17), or none (n = 13). Adequate revascularisation induces a large increase in physical working capacity because of an increased maximal heart rate and maximal cardiac output; stroke volume during maximal exercise and ejection fraction at rest were not modified, suggesting no major changes in left ventricular function. After unsuccessful coronary bypass surgery, the physical working capacity was unchanged despite an increased maximal heart rate; maximal cardiac output was unchanged and stroke volume during maximal exercise was significantly lower. These undesirable results are often associated with perioperative myocardial infarction and are attended by a decreased ejection fraction at rest; these data suggest an impaired left ventricular function after unsuccessful coronary bypass surgery. The results of partial revascularisation are intermediate but appear to be determined by the incidence of partial graft failure which is also often associated with perioperative myocardial infarction. From individual changes in data collected during maximal exercise testing, it is often impossible to predict the degree of revascularisation.

Idiopathic hypertrophic subaortic stenosis: long-term surgical results

The results of surgery in 21 patients with I.H.S.S. are reported. Dyspnea, angina pectoris and syncope were the most common symptoms in decreasing frequency. Before the operation, 5 patients were in New York Heart Association's functional class II, 10 in class III and 6 in class IV. The mean resting peak systolic pressure gradient was 66 mm Hg in 20 patients and mean left ventricular end-diastolic pressure was 14 mm Hg in 19 patients. The ventriculoseptomyectomy accomplished through a transaortic approach is the procedure of choice. The operative mortality rate was 14% (3 of 21 patients). There were 2 late deaths from congestive heart failure. Any sudden death did not occur. The remaining 16 patients have been followed up for a mean of 75 months (range 12 months to 11 years), 11 patients are in functional class I, 4 in class II and 1 in class III. Complete left-bundle-branch block occurred in 3 patients. Our study with a long post-operative follow-up period, documents that surgery results in good to excellent alleviation of symptoms in survivors. The elevated pre-operative left ventricular end-diastolic pressure has a significantly poor prognosis. We currently recommend surgery for the symptomatic patients who have not responded to medical therapy, not late in the symptomatic course of the disease.

Superiority of developed over total pressure for heart contractility indices in dogs

The independence of indices of contractility to Starling effects was tested in 6 closed-chest dogs. After vagal and beta-receptors blockade, indices calculated with total left ventricular isometric pressure (TP), were shown to be strongly dependent of rises in end-diastolic pressure (LVEDP) induced by dextran infusion. At LVEDP of 14.6 +/- 1.5, 22.2 +/- 1.1 and 32.8 +/- 1.5 mm Hg (+/- SEM), the peak value of velocity of the contractile elements calculated with total pressure (peak VCE, TP) diminished by 21, 40 and 50%, and the extrapolated value of VCE, TP at zero total pressure (Vmax, TP) diminished by 15, 30 and 44%. In contrast, indices calculated with developed pressure (DP = TP-LVEDP) at the same LVEDP were much less influenced, particularly the extrapolated value of VCE, DP at zero DP (V max, DP5) and (peak dP/dt)/DP did not significantly change. During angiotensin infusion, expected decreases in TP indices secondary to LVEDP rises were partially masked by simultaneous increases in contractility, and DP indices tended to rise. On the other hand, with minimal changes in LVEDP, as during calcium injection and paired stimulation, increases in TP and DP indices demonstrate inotropic effects equally well. Our study also shows that, besides Vmax calculated with DP, the instantaneous ratio of peak dP/dt and DP can also be proposed as a simpler and thus more convenient index of contractility independent of volume changes.

Maximal exercise testing in patients with spontaneous angina pectoris associated with transiet ST segment elevation. Risks and electrocardiographic findings

Six patients with spontaneous angina associated with transient ST segment elevation had a multistate maximal exercise (bicycle) test. In 5 patients, typical electrocardiographic changes were recorded during exercise, namely ST segment elevation often accompanied by an increase in the voltage of the R wave and a widening of the QRS complex. Four of these patients developed severe rhythm disturbances: ventricular tachycardia (2 cases) and ventricular flutter (1 case) were the reason for early interruption of the test in 3 patients, while 1 patient had a short run of ventricular tachycardia after exercise. These rhythm disturbances which spontaneously regressed in all cases were consistently preceded by obvious ST elevation and in 2 patients were attended by slight chest discomfort. Maximal exercise testing of patients suspected of variant angina provides important diagnostic information in many patients, but the risks of potentially lethal arrhythmias should be considered and resuscitation facilities should always be immediately available.