Relationship between function and perfusion early after acute myocardial infarction.

To assess the relationship between baseline left ventricle function, functional reserve and resting myocardial perfusion in patients with acute myocardial infarction (AMI). After AMI the presence of dysfunctioning but viable myocardium plays a determinant role in clinical outcome. Regional ventricular function was evaluated by echocardiography both in resting conditions and during dobutamine infusion (10 microg/kg/min). Perfusion was assessed by magnetic resonance imaging in a single slice approach where the first pass of an intravenously injected bolus of gadolinium-based contrast agent was followed through six regions of interest within the myocardium. In each patient a region with normal function was used as reference and the cross-correlation coefficient (CCC), which described the myocardial perfusion relatively to the reference region (CCC = 1 means equivalent perfusion), was obtained for the other five myocardial regions. Twenty-two patients were enrolled into the study. Sixty-one segments had normal function and normal perfusion (CCC = 0.92+/-0.23). The perfusion deficit was more marked in the 29 regions with resting akinesia-dyskinesia than in the 20 hypokinetic regions (CCC = 0.71+/-0.45 vs. 0.84+/-0.23; p < 0.05). Out of the 29 regions with resting akinesia-dyskinesia the 13 segments which showed functional improvement following dobutamine had a higher resting perfusion than the 16 segments which were unresponsive to dobutamine (CCC = 0.83+/-0.32 vs. 0.61+/-0.52, p < 0.05). Similarly, out of the 20 regions with resting hypokinesia the 11 segments having functional reserve showed an higher resting perfusion than the segments which did not (0.96+/-0.21 vs. 0.69+/-0.19; p < 0.05). Early after AMI, the perfusion deficit reflects the severity of the mechanical dysfunction. In regions with baseline dyssynergy resting perfusion is, in general, higher when contractile reserve can be elicited by stress-echo.

Nitrate tolerance in patients with effort angina.

BACKGROUND: In some patients with chronic stable angina the beneficial effects of nitrates may result not only from a reduction in venous return, but also from their action on coronary circulation. In these patients, rate-pressure product at ischemia (RPPI) increases to > 2500 bpm x mmHg after sublingual nitrates (SLN). The relative susceptibility of the venous system and the coronary circulation to the development of nitrate tolerance and the effects of two different drug schedules on the development of tolerance were investigated in patients with these characteristics. METHODS: Five patients were treated with isosorbide-5-mononitrate (IS5MN) 20 bid (8.00 am and 3.00 pm) for 1 week (Group 1) and 5 patients with IS5MN 40 bid (8.00 am and 8.00 pm) for 1 week (Group 2). Tolerance was identified as the decreased effect of SLN; the effects of nitrates were evaluated in relation to: reduction in left ventricle area (delta LVA), which had been measured using equilibrium radionuclide ventriculograms in LAO 45 degrees; this area was considered as an index of the venous return effects; increase in RPPI (delta RPPI), which had been assessed by ergometric test; RPPI was considered an index of coronary flow reserve. Measurements of LVA and RPPI were made in wash-out at the start of the study (delta LVA 1 and delta RPPI 1) and after 1 week of treatment (delta LVA 2 and delta RPPI 2). The mean values of the differences were then evaluated and compared using Student's "t" test. RESULTS AND CONCLUSIONS: In Group 1 patients delta LVA 2 and delta RPPI 2 showed values which were similar to delta LVA 1 and delta RPPI 1 (mean value delta LVA 2 47 vs mean delta LVA 1 48.2 pixels, p = ns; mean value delta RPPI 2 5264 vs mean delta RPPI 1 5536 bpm x mmHg, p = ns). These results suggest that Group 1 patients did not develop tolerance either at the coronary or at the venous level. In Group 2 patients, delta LVA 2 was significantly lower than delta LVA 1 (mean delta LVA 2 18.4 vs mean delta LVA 1 54 pixels, p < 0.01). This finding indicated tolerance to nitrates at the venous level. On the other hand, in all Group 2 patients, values of delta RPPI 2, though lower than delta RPPI 1 (mean delta RPPI 2 3095 vs mean delta RPPI 1 6083 bpm x mmHg, p < 0.01) were still higher than 2500 bpm x mmHg, indicating that the effect of nitrates at the coronary level was preserved. These data suggest that in patients treated with high doses of nitrates, the effect of these drugs at the coronary level is still present when tolerance has already developed at the venous level.

[Buprenorphine and pentazocine in acute myocardial infarct. Study for a differential use]. / Buprenorfina e pentazocina nell'infarto miocardico acuto. Studio per un impiego differenziato.

Morphine is known as the best analgesic for patients with acute myocardial infarction complicated by heart failure. In patients with uncomplicated acute myocardial infarction, buprenorphine has recently been indicated as an alternative to the widely used pentazocine. In order to verify if the haemodynamic effects of the two drugs differed, a randomized double-blind controlled trial was performed on 20 patients with uncomplicated acute myocardial infarction: 10 patients were treated with i.v. pentazocine 30 mg. and 10 patients with buprenorphine 0.30 mg. (equianalgesic doses). Right atrial, ventricular and pulmonary artery and capillary pressure, cardiac index, total pulmonary and total systemic resistance were measured before testing and 15', 30', 60', 180' and 240' after drug injection. PO2 was measured before drug injection and 30' and 60' later. Data were analyzed using the Wilcoxon test. All patients in each group showed uniform results: pentazocine increased total systemic resistance (mean increase 17%) while buprenorphine lowered it (mean reduction 12%) (P less than 0.05). Pentazocine lowered cardiac index (mean reduction 5.9%) while buprenorphine increased it (mean increase 9.3%) (P less than 0.05). Maximum changes occurred within 60' after the administration of both drugs. The other parameters did not change significantly from basal values. These results suggest that in patients with acute myocardial infarction uncomplicated by heart failure pentazocine and buprenorphine may be used in different haemodynamic situations. In the cases in which a reduction in total systemic resistance is desired, buprenorphine seems most suitable. However, in the presence of vagal reaction for instance, pentazocine may be administered.

[Cardiovascular complications of severe tetanus (author's transl)]. / Problemi cardiologici in corso di tetano.

Cardiovascular complications of severe tetanus are essentially represented by cardiac arrhythmias and hypertension. An excess of catecholamines is responsible for these complications. Tetanus toxin causes indeed a sympathetic overactivity which is due partly to a central stimulation and partly to a peripheral one. All that means the best treatment of cardiovascular complications of tetanus is represented by adrenergic blocking agent.