INDEX vasodilators

Dobutamine increases cardiac index because of inotropic stimulation, arterial vasodilation, and a variable increase in heart rate. It causes relatively little change in mean arterial pressure compared with the more consistent increases observed with dopamine. 

Sodium nitroprusside is a mixed arterial-venous vasodilator that acts directly on vascular smooth muscle to increase cardiac index and decrease venous pressure. Despite its lack of direct inotropic activity, nitroprusside exerts hemodynamic effects that are qualitatively similar to those of dobutamine and milrinone. However, nitroprusside generally decreases PAOP, SVR, and blood pressure more than those agents do. 

Administration by inhalation has been explored by Brilli [124], mentioned previously for his work with NONOates. Here he uses one of these same NONOates, DMAEP/NO (see Fig. 8.11), in aerosol form. When administered in an aerosolized state, DMAEP/NO again shows selective pulmonary vasodilation in a porcine model. This is achieved without affecting the systemic vascular resistance index (SVRI) or the cardiac index (Cl). Work from the same year by Adrie et al. [125] compared aerosolized DEA/NO with aerosolized SNP and inhaled NO, in sheep. As the NONOate has a short half-life (2.1 min), it was predicted that this would be a selective pulmonary vasodilator. However, compared with inhaled NO this was not observed, though SNP... 

Dysregulation of the vascular endothelium has emerged as a critical component of most thrombotic disorders [10, 21]. Often without any anatomical sign of atherosclerosis, many cardiovascular diseases express a vasomotor abnormality termed endothelial dysfunction, indexed clinically as impaired endothelium-dependent vasodilation [31]. Although its mechanism is multifactorial, endothelial dysfunction is characterized by diminished vascular NO production and/or bioavailability [32]. The... 

Figure 3.4 Graph showing mean values for cardiac index (Cl) and heart rate (HR) in young (n=20) and elderly (n=20) patients during induction of anaesthesia with isoflurane (1 MAC) in 100% oxygen. Data from McKinney MS, Fee JPH, Clarke F J. British Journal of Anaesthesia 1993 71 696-701.) anaesthesia. Marked cerebral vasodilation occurs with an increase in intracranial pressure. This can be mitigated by hyperventilation even in the presence of a space-occupying lesion.

The hemodynamic effects of ritodrine have been assessed in 12 fetuses by cardiac and extracardiac Doppler sonography (1). Ritodrine significantly increased maternal and fetal heart rates, left cardiac stroke volume, and cardiac output. There was also an increase in the pulsatility index of the middle cerebral artery and a fall in the pulsatility index of the umbilical artery during ritodrine infusion. The authors suggested that ritodrine vasodilates fetal vessels in the placenta. 

Adrenergic receptor (ADBR2) Antagonists (e.g., albuterol, terbutahne) Bronchodilation, susceptibility to agonist-induced desensitization, cardiovascular effects (e.g., increased heart rate, cardiac index, peripheral vasodilation)... 

FIGURE 7 Percentage changes in hemodynamic variables from baseline values during a 15-rain administration of inhaled nitric oxide in postoperative neonates with no residual anatomic obstruction to pulmonary blood flow. There was a marked pulmonary vasodilating effect. HR, Heart rate Cl, cardiac index BP, systemic artery pressure SVR, systemic vascular resistance PAP, mean pulmonary artery pressure PVR, pulmonary vascular resistance. 

Patients with left atrial hypertension may have an elevated pulmonary vascular resistance because the cardiac index is low, the pulmonary vasculature is constricted, or there is fixed pulmonary vascular obstructive disease with a reduction in recruitable lung vessels. Peroperative assessment may be aimed at increasing cardiac output with drugs such as dobutamine or by combining vasodilation and an increase in cardiac output with drugs such as nitroprusside or prostacyclin. The use of catecholamines or systemic vasodilators is not without risk, especially in patients with left ventricular outflow tract obstruction, as in two of our patients, or in patients with... 

Oral ingestion of up to 1 mmol (ca. 100 mg) of histamine does not elicit toxic symptoms in normal individuals (Motil and Scrimshaw, 1979). However, vasodilation and increased heart rate result on intravenous administration of 0.07 /imol, demonstrating the importance of histamine-metabolizing enzymes in the digestive tract. More research is needed to define nontoxic levels of histamine in foods which may contain other substances that potentiate the action of histamine, e.g., putrescine and cadaver-ine (Bjeldanes etal., 1978). Construction of an overall biogenic amine index may be valuable for the establishment of regulatory fimits (Joosten, 1988). 

Microalbuminuria in healthy subjects is associated with atherosclerotic risk factors such as increased systolic and diastolic blood pressure (BP) decreased Apo A1 and HDL-C levels (12). Minor derangements of renal function are associated with an increase in CVD risk factors and promote progression of atherosclerosis (reviewed in ref. 14). However, in a separate study in contrast to BP, body mass index (BMl), and triglycerides (TGs), there was no relation between urinary albumin excretion and flow-mediated vasodilation in apparently healthy subjects. This suggests that the presence of atherogenic risk factors precedes the development of endothelial dysfunction in microalbuminuric but otherwise healthy subjects (75). 

Eig. 4 displays examples of LV contractility responses during four different tests (31-agonist Dobutamine infusion, autonomic blockade, tilt test and vasodilator SNP infusion. In the first three tests the kinetics of changes in the non-inva-sive index l/(PEPz-5) was quite similar to the changes in dP/dtImax, but the vasodilator SNP sometimes induced the inverse responses of the PEP-based index and dP/dtlmax. It is likely that a decrease in contractility reflected by the dP/dtUax resulted from the lower diastolic filling of the ventricle due... 

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