Br Heart J: first published as 10.1136/hrt.40.3.256 on 1 March 1978. Downloaded from British Heart Journal, 1978, 40, 256-267 Value of systolic and diastolic time intervals Studies in normotensive and hypertensive 50-year-old men and in patients after myocardial infarction JOHN WIKSTRAND, GORAN BERGLUND, LARS WILHELMSEN, AND INGEMAR WALLENTIN From the Department of Clinical Physiology and the Section of Preventive Cardiology, Department of Medicine I, Sahlgren's Hospital, University of Goteborg, Sweden SUmAMRY Systolic and diastolic time intervals were studied non-invasively in a group of untreated hypertensives (n = 19) and a reference group (n = 36), all derived from a random population sample of 50-year-old men, and in a myocardial infarct group (n = 67) representative of men aged 48 to 57 years surviving infarction. The results showed that only the electromechanical interval, pressure rise velocity, and the interval between the aortic component of the second heart sound (A2) and the 0-point in the apex cardiogram were useful discriminants between the three groups. There were no significant differ- ences in systolic time intervals between the groups and the systolic time intervals were of limited diag- nostic value as signs of impaired left ventricular function. The infarct patients had a significantly longer electromechanical interval (34 ms) than individuals in the reference group (27 ms), indicating delayed start ofthe systolic contraction in the infarction group. The pre-ejection period predicted the isovolumetric contraction time with great uncertainty in the infarct group. Increased pressure rise velocity (resting diastolic blood pressure/isovolumetric contraction time http://heart.bmj.com/ >1200 mmHg/s) was seen in 38 per cent of the infarct patients and 67 per cent of the hypertensives, compared with 4 per cent in the reference group, indicating more powerful contraction in infarct patients and hypertensives as compared with subjects in the reference group. The difference could not be explained by a difference in preload as judged from the a-wave in the apex cardiogram. The A20 interval was significantly prolonged (>150 ms) in 74 per cent of the infarct patients and 56 per cent of the hypertensives, as compared with 3 per cent in the reference group, indicating prolonged relaxation or prolongation of the early filling phase of the left ventricle in hypertensives and on September 24, 2021 by guest. Protected copyright. infarct patients. This was mainly related to factors other than heart rate and blood pressure. Non-invasively derived systolic time intervals for LVET with consequent prolongation of the assessment of left ventricular function such as the PEP/LVET ratio have been ascribed to impaired left ventricular ejection time (LVET) and the pre- contractility of the left ventricle. These changes in ejection period (PEP) have been extensively studied. PEP and LVET have also been found to correlate PEP comprises the isovolumetric contraction time well with contractility and measures of pump (ICT) and the interval from the beginning of de- function (Garrard et al., 1970; Ahmed et al., 1972). polarisation to the start of the systolic contraction, Despite this, many authors have doubted the value i.e. the electromechanical interval (EMI); it has of the systolic time intervals (Hodges et al., 1972; been pointed out that the ICT should provide a Parker and Just, 1974). better measure of left ventricular function than the Several authors have used apex cardiography to PEP (Kumar and Spodick, 1970). measure the interval between the aortic component Prolongation of the PEP and shortening of the of the second heart sound (A2) and the 0-point in the apex cardiogram in order to study isovolumetric Received for publication 25 February 1977 relaxation (Tavel et al., 1965; Benchimol and Ellis, 256 Br Heart J: first published as 10.1136/hrt.40.3.256 on 1 March 1978. Downloaded from Systolic and diastolic time intervals 257 1967; Kumar and Spodick, 1970). Transducers with from hospital at the Post-Myocardial Infarction short low frequency time constants have often been Clinic by physicians trained together to achieve a used. These transducers, however, shorten the A20 standardised treatment regimen (Elmfeldt et al., interval and tend to smooth out differences between 1975b). a prolonged and a normal A2O interval (Johnson During an observation period of one year 100 et al., 1971; Wikstrand et al., 1977). acute myocardial infarcts were recorded. Before Most of the above-mentioned studies were 31 December 1972, 18 patients were selected by carried out in small selected groups of hospital means of a random number table to participate in patients. The aim of the present study was to in- another study. These patients were not followed up vestigate the value of non-invasively registered time at the Post-Myocardial Infarction Clinic and were intervals in representative groups of untreated excluded from our study. Twelve patients died hypertensives and postinfarction patients, and to within three months of onset of infarction and two establish the normal limits for these intervals in patients were excluded from the analysis, one 50-year-old men. because of mitral stenosis and one because of aortic valvular disease. One patient who had had a cere- Groups studied brovascular stroke was unable to participate. The mean age for the infarct group was 531 years (range All subjects of a random population sample of 50- 48 to 57). Fifty-nine patients had primary infarcts year-old men in Goteborg, Sweden (Wilhelmsen and 8 patients suffered from reinfarction. During et al., 1972), with untreated essential hypertension the period of acute care in hospital 14 patients had were allocated to a hypertensive group (n=35). signs of cardiogenic shock, defined as a systolic Essential hypertension was defined by casual blood blood pressure below 100 mmHg with cold sweaty pressure above 175 mmHg systolic or 115 mmHg skin, or left ventricular failure, defined as basal diastolic on two separate occasions and a negative rales over the lungs persisting after cough or diagnostic examination for secondary hypertension evidence of congestion on a chest x-ray film. At the (Wilhelmsen et al., 1973). time of the non-invasive examination 21 patients A reference group (n=73) with casual blood were on digitalis therapy, 7 on ,-blockers, and a pressure below 175 mmHg systolic and 115 mmHg further 4 on both digitalis and ,3-blockers. Two diastolic was obtained from the same population by years after the non-invasive investigation 9 of the http://heart.bmj.com/ drawing a 10 per cent subsample at random. The patients in the infarct group had died from ischae- way in which these groups were selected (Fig. 1, mic heart disease, verified at necropsy in all cases. upper panel) has been described in detail elsewhere (Wikstrand et al., 1976). The infarct group Methods (n=67) consisted of men living in G6teborg, born between 1916 and 1924, who suffered a hospital Conventional electrocardiograms, carotid pulse verified myocardial infarction during a 12-month tracings, apex cardiograms, phonocardiograms, period (15 July 1972 to 14 July 1973) and survived and resting blood pressures were all recorded on a on September 24, 2021 by guest. Protected copyright. for at least 3 months (Fig. 1, lower panel). The direct writing ink-jet 7-channel mingograph (EM non-invasive investigations were carried out in 81, Siemens-Elema AB, Sweden) with a linear a randomised half of the reference group (n=36) frequency response from 0 to 500 Hz and 30 per and of the hypertension group (n= 19) (Fig. 1) and cent amplitude reduction at 650 Hz. The phono- in all infarct patients (n=67). cardiograms were recorded using a phonopre- Sahlgren's Hospital takes care of practically all amplifier (EMT 22) with electrical filters that patients sustaining a myocardial infarct in G6teborg. together with a piezoelectric microphone (EMT Suspected cases of myocardial infarction were re- 25 C) gave six frequency ranges including one aural corded by the staff responsible for the Myocardial frequency range. The pulse tracings and apex Infarction Register in Goteborg. Acute myocardial cardiograms were obtained using crystal transducers infarction was considered to have occurred when at (EMT 510 C) with low frequency time constants least two of the three criteria-central chest pain, between 1 9 and 4-6 s (depending on a capacitance- transient rise of serum aspartate transaminase, or resistance product, decided by the individual electrocardiographic abnormalities-were fulfilled. amplification used for each curve) and connected The patients so identified have been shown to by a 25 to 40 cm rubber tube to a specially designed constitute at least 90 per cent of the total number of capillary-damped funnel pick-up, 2-5 cm in di- surviving myocardial infarction patients in the ameter, giving a frequency response of at least 0'08 population of Goteborg (Elnfeldt et al., 1975a). (at low frequency time constant 1-9 s) to 65 Hz They were systematically cared for after discharge (-3dB) (Wikstrand et al., 1977). The paper speed Br Heart J: first published as 10.1136/hrt.40.3.256 on 1 March 1978. Downloaded from 25828ohn Wikstrand, Gdran Berglund, Lars Wilhelmsen, and Ingemar Wallentin All 50-year-old men in Goteborg n = 3372 - Randoml/3 samrI e -I |l n = 1F2'2 r- http://heart.bmj.com/ All men born 1916-24 in Goteborg n= 26800 Registered acute infarcts during one year n=100 on September 24, 2021 by guest. Protected copyright. Rarndomly allocated to other study -18 Excluded: died within three months -12 Excluded:di1seasevalvular - 2 r Excluded: stroke -1 Infarct group studied n=67 Fig. 1 Groups studied. Upper panel: schematic representation of the selection of the hypertensive and reference groups. Lower panel: schematic representation of how the infarction group was derived.