In 10 patients with supraventricular tachycardia who underwent an electrophysiological study the ectopic atrial origin of the tachycardia could be demonstrated by the intracavitary localization of the earliest depolarized point (six cases in the right atrium and four cases in the left). Vagal stimulation and/or the i.v. infection of ATP induced or increased the degree of AV block during tachycardia; in five cases ATP interrupted the tachycardia. On the basis of their clinical and electrophysiological behavior, the patients were divided into two groups. In the first one (6 patients) tachycardia was persistent, started following late atrial beats with the same morphology of the subsequent and showed a progressive initial rate increase (warm-up phenomenon); programmed atrial stimulation failed to start and interrupt it. In the second group (4 patients) tachycardia was paroxysmal or repetitive, started following early atrial beats and could be induced and interrupted by programmed atrial stimulation. With respect to the electrophysiological characteristics of each group the authors try to define the possible mechanism responsible for the tachycardia (automaticity and micro-reentry).

Adenosine Triphosphate↗

PubMed1977

Favorable effects of hyaluronidase on electrocardiographic evidence of necrosis in patients with acute myocardial infarction.

To evaluate hyaluronidase's effect in reducing post-infarction myocardial necrosis, we randomized 91 patients with anterior infarction to control (45) or to hyaluronidase-treatment (46) groups. A 35-lead precordial electrocardiogram was recorded on admission and seven days later. Hyaluronidase was administered intravenously after the first electrocardiogram and every six hours for 48 hours. QRS-complex changes were analyzed to assess the drug's effect. Precordial sites with ST-segment elevation (larger than or equal to 0.15 mV) on the initial electrocardiogram that retained an R wave were considered vulnerable for the development of electrocardiographic signs of necrosis. The sum of R-wave voltages of vulnerable sites fell more in the control group than in the hyaluronidase group (70.9 +/- 3.6 per cent [+/- 1 S.E.M.] vs 54.2 +/- 5.0 per cent P less than 0.01). Q waves appeared in 59.3 +/- 4.9 per cent of the vulnerable sites in control versus 46.4 +/- 4.9 per cent in hyaluronidase-treated patients (P less than 0.05). Thus, hyaluronidase reduced the frequency of electrocardiographic signs of myocardial necrosis.

Acute Disease↗

PubMed1977

[Effects of nitroglycerin on pressure-volume diastolic relationships of the left ventricle in patients with coronary disease].

In fifteen patients with coronary artery disease who underwent hemodynamic studies, pressure measurements and left ventricular angiography were performed prior and 5' after the administration of 0.4 mg of spray nitroglycerin (TNG). Two different expressions of left ventricular diastolic compliance (dV/dP - V at end-diastole, delta V/delta P normalized by end-systolic volume-VTS) were assessed in basal conditions and after TNG. Nitroglycerin decreased left ventricular end-diastolic pressure (control 22.7 +/- 7.6 mmHg; TNG 11.4 +/- 6.1 mmHg, p less than 0.001) left ventricular end-diastolic volume (control 138 +/- 54 ml/m2, TNG 122 +/- 54 ml/m2, p less than 0.001) and improved compliance indexes (dV/dP - VED control 1.3 +/- 0.5 10(-2)/mmHg; TNG 4.6 +/- 4.3 10(-2)/MMHg; p less than 0.01; delta V/delta P - VTS control 0.071 +/- 0.04 mmHg-1; TNG 0.170 +/- 0.14 mmHg-1, p less than 0.01). TNG decreased the average value of modulus of chamber stiffness K (control 0.031 +/- 0.009; TNG 0.028 +/- 0.008, p less than 0.02) shifting the pressure-volume curve in some patients rightward and downward. Thus the increase of end-diastolic compliance (dV/dP - VED) is due to preload reduction and in patients who presented a marked decrease in K, also to the shift of the pressure-volume relation. These effects of TNG have important implications because they permit patients with coronary artery disease to engage in a given effort at a significantly lower end-diastolic pressure, avoiding pulmonary congestion.

Adult↗

PubMed1977