European journal of cardiology最新文献

Increased adrenergic activity, often manifested in chronic angina, is likely to influence adversely the course of the disease. In view of the inhibitory effect of clonidine (CL) upon the adrenergic nervous system, the effectiveness of small doses of CL in chronic angina was evaluated in a double-blind crossover study on 60 patients suffering at least 5 coronary pains per week in spite of routine medication. CL was given orally in a dose of 2 x 75 microgram/day for a 2 wk. Reduction in frequency of coronary pains by at least 50% was observed in 53.7% of patients, total nitroglycerin consumption decreased from 322 to 174 tablets/week, and ergometric performance increased from 168 to 283 W x min/patient. Urinary excretion of adrenaline and noradrenaline diminished. Blood pressure and heart rate were not considerably changed. Mild and transient side effects occurred in 10 patients, 9 of them completed the trial. It is concluded that CL in low doses is effective and safe in patients with chronic angina, presumably by alleviating adrenergic strain.

In the immediate postoperative period, echocardiography was used to study left ventricular function in 69 children after correction of various congenital cardiac malformations. Left ventricular contractility indices and systolic time intervals measured from aortic cusp echoes were repeatedly obtained during the fist postoperative week. The degree of impairment of left ventricular function was assessed for different diagnostic groups and are tabulated. Decrease in left ventricular function was strongly correlated to operating time, cardiac bypass time, and aortic clamping time, the most important factor being cardiac bypass time. Left ventricular ejection time (LVET) was the most useful parameter of cardiac function in the immediate postoperative period and was of prognostic value in 5 patients who died early in that period. Abnormal septal movement was seen in most patients, but usually normalized within 2 wk. After extensive operations, changes in the movement pattern of the aortic leaflets were also seen. Although pericardial effusion was commonly found during the postoperative period, it did not indicate postcardiotomy syndrome and disappeared spontaneous within 2 mth.

Exercise responses depend on work load and its pattern of delivery. Administering a very brief ("impulse") load aims to elicit significant responses through biologic sensitivity to rate - rather than degree - of change. Electrocardiograms, systolic time intervals (STI) and heart rate (HR) were recorded continuously in 10 normal subjects during and after brief (20-sec) bicycle exercise at 50, 100 and 150 W. The purpose of this protocol was to identify a low load impulse-type exercise challenge which would be optimal in terms of (a) reproduction of the time course of exercise changes produced by longer duration (steady-state) exercise, (b) rapid achievement of quantitative responses reaching some or all of the steady-state changes at comparable work load, and (c) absence of ST changes in normal subjects. The onset of exercise produced the greatest rates of change. Directional changes and time course of all measurements paralleled those of steady-state exercise and recovery at the same loads: HR, ejection time index (ETI) and corrected ejection time (ETc) increased sharply; preejection period (PEP) and PEP/LVET fell sharply. Ejection time (LVET), stable through most of exercise, "paradoxically" decreased for up to 15 sec of recovery despite decreasing heart rates. For all measurements, restitution to control levels was complete by one minute of recovery.

The successive deterioration of left ventricular pump function during exercise-induced angina pectoris was studied in 20 candidates for aortocoronary bypass surgery. Left ventricular stroke work and power were calculated from continuous left ventricular pressure recordings and repeated measurements of cardiac output every 30 sec using the thermodilution technique. The average left ventricular enddiastolic pressure (LVEDP) increased continuously during exercise whereas stroke work index (SWI) did so only in the beginning of the exercise period up to a maximum value and then fell towards the end of exercise. The onset of angina occurred at an average LVEDP of 34 mm Hg when SWI had already started to fall in most patients. During exercise all patients had markedly lower SWI than normals. Patients with high coronary arteriographic score and patients with a previous myocardial infarction had significantly lower SWI during exercise than those with low score or those without a previous infarct. At rest there were no differences between these groups which emphasises the importance of haemodynamic measurements under stress conditions in patients with ischaemic heart disease.

A 36-yr-old woman and a 46-yr-old man had infective endocarditis of the mitral valve. Examination by 2-dimensional dynamic echocardiography demonstrated large mobile vegetations in both patients, and the display pointed to an ominous risk of embolism. Heart surgery with valve replacement was performed, the main indication being prophylaxis against embolism; the operative findings seemed to justify the assumption of imminent risk of embolism. It is suggested that the display of dynamic morphology of valvular vegetations by 2-dimensional echocardiography can be useful in identifying a subset of patients at high risk of embolism during infective endocarditis. However, more experience is needed before definite conclusions can be drawn regarding the role of early operation as prophylaxis against impending embolism.

Ventricular arrhythmias were produced in 12 dogs 4 to 6 days after coronary artery ligation by programmed ventricular stimulation. The electrocardiogram and 7 composite electrograms from endocardial and epicardial surfaces of the ischemic, border and normal zones, as well as from the right ventricle, were recorded during and after programmed ventricular stimulation. The ventricular arrhythmias were preceded and sustained by delayed, fragmented activity in the ischemic epicardial zone bridging diastole. Efferent pathways from the ischemic epicardium led to direct epicardial spread to adjacent normal epicardium in most instances. Efferent pathways into the endocardial regions were also observed, but to a lesser extent. The efferent reentry pathways led to both ventricles, and produced right and left ventricular arrhythmias in 8 of the 12 dogs; they were exclusively of left ventricular origin in the remaining 5. Classification of right and left ventricular arrhythmias may only be related to the exit points and not necessarily to their origin.

A new multivariate stepwise linear regression analysis (Cox's model) with survival time as prognostic endpoint was utilized in 281 patients with acute myocardial infarction. From 18 prognostic factors occurring during the first 5 days in the Coronary Care Unit a new prognostic index was calculated for the chance of survival in the first 36 days after admission. The significant prognostic variables were heart failure, cardiogenic shock, atrioventricular block and age. The total group of patients was classified in 6 subgroups with different mean indices and prognosis. There were 2 large groups of patients with relative bad and good prognosis (with and without heart failure). Over half of the patients had no prognostic variables. There was a trend of overestimating the expected deaths. A definite cardiac cause of death was shown by 23 patients (82%). This prognostic index based on the 4 variables can for the individual patient predict the chance of survival, which can be the basis of an individualized duration of hospital stay.

With the application of new power sources to pacemakers, considerable improvement has been achieved in the theoretical implant lifetime of current pulse generators, and equally reliable electrode leads will be necessary to ensure long-term pacing. The durability of the electrodes implanted in the past ten years in this centre has been carefully studied. The findings suggest that the use of a more durable conductor material and development of the concept of a 'fail safe' lead (using multi-filament conductors or a secondary conductive pathway along the electrode) will be necessary to match with the implant lifetime of the newer pulse generators. The diagnosis and management of broken conductors is discussed.

The need for effective palliation of critically ill infants born with total anomalous pulmonary venous connection is reappraised. Careful study of autopsy specimens in patients with this cardiac malformation (patient ages ranging from newborn to 5 1/2 mth) revealed 4 favorable anatomic dispositions in 16 selected hearts: (1) a horizontal vein or a lobar vein larger than 3-mm size was present in every case; (2) these veins were of adequate length for a shunt anastomosis; (3) the heart could be rotated for easy access to the left atrium; and (4) one of the two separate connecting veins in the mixed type could be utilized. Based on morphologic observations and trial procedures on the autopsy specimens, a new palliative operation is proposed which can be performed under normothermia and without cardiopulmonary bypass.

Echocardiographic aortic root motion in systole was studied in 57 patients: 13 normal subjects, 4 patients with left ventricular (LV) volume overload due to anaemia, 16 patients with mitral incompetence, 13 with aortic incompetence and 11 with mitral stenosis. In normal subjects, patients with mitral stenosis and in patients with LV volume overload, in whom the increased stroke volume was ejected forwards into the ascending aorta (anaemia, aortic incompetence) the amplitude of motion of the posterior aortic wall (vp), the aortic widening fraction (AWF) and total aortic motion (TAM) were increased. In mitral incompetence, however, despite the large increase in total LV stroke index, there was a decrease in vp (P less than 0.01), AWF (P less than 0.001) and TAM (P less than 0.001), and the decrease in aortic motion for a given stroke index was related to the mitral regurgitant fraction, indicating that aortic wall movement in systole depended predominantly on forward ejection of the LV stroke volume. Reduced echocardiographic aortic root motion and widening during systole are useful echocardiographic signs of mitral regurgitation.