Natural evolution of left ventricular haemodynamics following uncomplicated acute myocardial infarction.
In an attempt to investigate the changes in left ventricular haemodynamics following uncomplicated myocardial infarction 95 patients with definite electrocardiographic signs of infarction, without clinical signs of cardiac failure, were monitored with a Swan Ganz catheter for the first 24 hours after admission to hospital. The median delay from onset of symptoms was 6.8 hours. Mean heart rate increased (83-86 beats/min; P less than 0.05) while stroke volume index fell (38.4-36.6 ml/m2; P less than 0.05); cardiac index therefore remained unchanged during the observation period. As a result of a fall in arterial pressure both systemic vascular resistance and left ventricular stroke work index fell significantly (P less than 0.01). Pulmonary wedge pressure also fell (13.6-10.5 mm Hg; P less than 0.001), but this fall was confined to patients whose initial reading was above the median of 13 mm Hg. Pulmonary wedge pressure fell both among the 41 patients who required some medical therapy (15.6-10.8 mm Hg; P less than 0.001) and the 54 who received no medication throughout the 24 hours (12.0-9.8 mm Hg; P less than 0.05). The 39 patients with anterior wall infarction had higher baseline pulmonary wedge pressure and systemic vascular resistance than the 42 with inferior wall infarction. Later the stroke volume and stroke work index were persistently lower reflecting the greater degree of impairment of left ventricular function in anterior wall infarction. In conclusion, following an uncomplicated myocardial infarction, cardiac index was maintained, despite a fall in stroke volume, by an increase in heart rate. Pulmonary wedge pressure showed both a spontaneous fall and a fall in those patients given additional medical therapy during the study period.
D P
DP
Murray
H M
HM
Corbeij
P H
PH
Dunselman
P H
PH
Held
A
A
Hjalmarson
K
K
Swedberg
D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D006328:Cardiac Catheterization; D002302:Cardiac Output / Q000187:drug effects; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000627:therapeutic use; D009203:Myocardial Infarction / Q000188:drug therapy / Q000503:physiopathology*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D011897:Random Allocation; D014655:Vascular Resistance / Q000187:drug effects
D008790:Metoprolol