Pulmonary arterial wedge pressure

Preload The stretched condition of the heart muscle at the end of diastole just before contraction volume in the left ventricle at the end of diastole estimated by the pulmonary artery occlusion pressure (also known as the pulmonary artery wedge pressure or pulmonary capillary wedge pressure). 

Hypertrophic cardiomyopathy (IHSS) Serious adverse effects were seen in 120 patients with IHSS (especially with pulmonary artery wedge pressure more than 20 mm Hg and left ventricular outflow obstruction) who received oral verapamil at doses up to 720 mg/day. Sinus bradycardia occurred in 11%, second-degree AV block in 4% and sinus arrest in 2%. 

The IV administration of propafenone is accompanied by an increase in right atrial, pulmonary arterial, and pulmonary artery wedge pressures in addition to an increase in vascular resistance and a decrease in the cardiac index. A significant decrease in ejection fraction may be observed in patients with preexisting left ventricular dysfunction. In the absence of cardiac abnormalities, propafenone has no significant effects on cardiac function. 

Pulmonary hypertension is characterized by a chronically elevated pulmonary artery pressure. As described in previous sections of this chapter, under normal conditions, the pulmonary artery pressure has a systolic value of 18 to 25 mm Hg, a diastolic value of 6 to 10 mm Hg, and a mean value ranging from 12 to 16 mm Hg. Pulmonary hypertension exists when the pulmonary artery systolic and mean pressures exceed 30 and 20 mm Hg, respectively. In the disease state, the pressure in the pulmonary artery may fluctuate widely and is often so high that it equals the blood pressure in the systemic arterial bed. As would be expected, pulmonary vascular resistance is also extremely high in patients with pulmonary hypertension. In addition, patients with this disease exhibit an enlarged right ventricle and an enlargement of the main pulmonary artery and its branches. Systemic hemodynamic parameters, however, such as cardiac output, cardiac index, systemic artery pressure, and pulmonary artery wedge pressure are usually not elevated. 

Hemodynamic effects - Digoxin produces hemodynamic improvement in patients with heart failure. Short- and long-term therapy with the drug increases cardiac output and lowers pulmonary artery pressure, pulmonary capillary wedge pressure, and systemic vascular resistance. 

Pharmacology The principal pharmacological action of nitrates is relaxation of the vascular smooth muscle and consequent dilation of peripheral arteries and especially the veins. Dilation of the veins promotes peripheral pooling of blood and decreases venous return to the heart, thereby reducing left ventricular end-diastolic pressure and pulmonary capillary wedge pressure (preload). Arteriolar relaxation reduces systemic vascular resistance, systolic arterial pressure, and mean arterial pressure (afterload). Dilation of the coronary arteries also occurs. The relative importance of preload reduction, afterload reduction, and coronary dilation remains undefined. 

Ibutilide has no significant effects on cardiac output, mean pulmonary arterial pressure, or pulmonary capillary wedge pressure in patients with or without compromised ventricular function. 

Mechanism of Action AnACE inhibitor that suppresses the renin-angiotensin-aldos-terone system and prevents conversion of angiotensin I to angiotensin 11, a potent vasoconstrictor may also inhibit angiotensin II at local vascular and renal sites. Decreases plasma angiotensin II, increases plasma renin activity, and decreases aldosterone secretion. Therapeutic Effect Reduces peripheral arterial resistance, pulmonary capillary wedge pressure improves cardiac output and exercise tolerance. Pharmacokinetics ... 

Measurements of arterial pressure, cardiac output, stroke work index, and pulmonary capillary wedge pressure are particularly useful in patients with acute myocardial infarction and acute heart failure. Such patients can be usefully characterized on the basis of three hemodynamic measurements arterial pressure, left ventricular filling pressure, and cardiac index. One such classification and therapies that have proved most effective are set forth in Table 13-4. When filling pressure is greater than 15 mm Hg and stroke work index is less than 20 g-m/m2, the mortality rate is high. Intermediate levels of these two variables imply a much better prognosis. 

Definition Characteristic criteria of PPH include (I.) elevated pulmonary artery pressure (> 25 mm Hg), (2.) increased pulmonary vascular resistance (> 120 dyne/ sec/cm ), and (i.) normal pulmonary capillary wedge pressure (<15 mm Hg). An elevated transpulmonary gradient (mean pulmonary artery pressure/pulmonary capillary wedge pressure = > 10 mm Hg) is likewise used as a diagnostic criterion. (62, 70) The presence of portal hypertension is considered as a prerequisite for the development of PPH. 

In a retrospective view of 63 patients who received intravenous milrinone for more than 24 hours for advanced cardiac failure, the mean dose was 0.43 micro-gram/kg/minute and the mean duration of therapy 12 (range 1-70) days (14). After 24 hours of therapy there was significant improvement in pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac index. Because of the nature of the study, which was not placebo-controlled, it is impossible to be sure what events could have been attributed to the milrinone. However, the authors reported five cases of asymptomatic, non-sustained ventricular tachycardia, six of symptomatic ventricular tachycardia, and three deaths, one in ventricular tachycardia and two in heart failure. There was no difference in the incidence of these adverse events in patients who received milrinone for more than 7 days compared with the others. 

The adverse effects associated with the use of verapamil include constipation, sinus node blockade, prolongation of the PR interval, AV dissociation, hypotension, and pulmonary congestion." The risks may outweigh the benefits in patients with (1) a markedly elevated pulmonary capillary wedge pressure or pulmonary artery occlusion pressure, (2) a history of paroxysmal nocturnal dyspnea or orthopnea, (3) sick sinus syndrome or significant AV nodal disease in the absence of a permanent pacemaker, (4) low systolic blood pressure, and (5) a substantial outflow gradient.Verapamil should be avoided inpatients with heart failure owing to systolic dysfunction. There is no evidence that either /3-blockade or verapamil protects the patient from sudden cardiac death. 

Nesiritide is a human B-type natriuretic peptide, which binds to the particulate guanylate cyclase receptor of vascular smooth muscle and endothelial cells, leading to dose-dependent reductions in pulmonary capillary wedge pressure and systemic arterial pressure in patients with heart failure. It is indicated in the treatment of patients with acutely decompensated CHF who have dyspnea at rest or with minimal activity. 

Diuretics have become the cornerstone of all treatment regimens of CHF (III—II3). They can reheve symptoms of pulmonary and peripheral edema. In mild CHF, the thia2ide-type diuretics are adequate unless the GFR falls below 30 ml,/min, as compared to 120 ml,/min in normal subjects. Diuretics improve left ventricular function in CHF due in part to decrease of preload. Indapamide has been shown to cause reduction of pulmonary arterial pressure and pulmonary wedge pressure. 

---