Post-MI patients with PTSD have higher sympathetic and lower parasympathetic heart rate modulation activity, compared with patients with MI and no PTSD.

Background Heart rate variability HRV differs by the type and stage of the disease, by age, by environment, and so on. Criteria for normal, moderately changed and pathologic values of HRV lack for routine clinical work with different groups of cardiac patients.Methods Twelve time and frequency domain HRV variables were analysed from 24-h Holter ECG monitoring in 2578 ( ) consecutive patients of both sexes 57% male aged 15-91 ( ) mean 54" 13 years. Fifty-nine per cent of the patients were hospital out-patients, 15% came from the cardiac unit of an internal medicine department and 26% were undergoing stationary cardiac rehabilitation. Arrhythmias of aetiology other than coronary artery disease predominate in out-patients and coronary artery disease in in-patients. Limits of moderately and pathologically changed values were determined according to biostatistical principles.Results HRV differed by the age, sex and type of patients ( ) MANOVA P -0.001 . Heart rate and all HRV measures decreased with age. Females had a higher heart rate but more pronounced vagally modulated activity than males. Out-patients had better HRV than in-patients. The cut-off level for a ( pathologic standard deviation of the normal R -R interval a ) measure of overall HRV ranged from 75 ms in female out-patients to 44 ms in male patients from the cardiac unit. Different cut-points for 12 HRV measures were obtained for 12 sub-groups of patients. ConclusionIn view of the HRV differences between different cardiac patients, different limits of normal and decreased HRV are proposed for daily practice.

In contrast to the strong prognostic potential of HRV in patients with MI, decreased HRV has no prognostic significance in patients who have undergone CABG surgery.

Tolerance to nitroglycerin infusion (NG) can be overridden by dose escalation. The aim of this study was to define for how long it can be done for hypotensive efficacy of NG, in a coronary care setting. A prospective trial with an intra-individual therapeutic comparison was performed in 60 patients with acute myocardial infarction or unstable angina. Initial efficacy of NG was confirmed by a 10% blood pressure decrease (measured by cuff). Seventy-two-hour NG infusion was interrupted, for 30 minutes, every 12 hours. If blood pressure increased by 10% after infusion interruption, the infusion was continued at the previous rate. If blood pressure did not increase (detected tolerance--weakened efficacy of NG), the dose was increased until pressure decreased by 10% and the infusion was continued at the new dose. Failure to achieve hypotensive response, despite a 5-fold dose increase, indicated onset of resistance--completely lost hypotensive efficacy of NG. The majority of patients (49 out of 55) who developed tolerance, developed it during the first 36 hours, while the majority of those who developed resistance (33 out of 40), developed it within 60 hours of the infusion. Tolerance was overridden by dose escalation in 41 out of 55 patients, which was repeated in 31 patients. Complete restoration of NG action was possible over 24 hours in half the patients, and over 48 hours in one third of the patients. Three out of 34 patients who developed tolerance before the 13th hour did not develop resistance during the following 60 hours of dose up-titration. The conclusion is that tolerance to NG can be overridden by dose escalation in the majority of patients for a significant period of time, which is useful in clinical practice.

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