Regional myocardial function at the papillary muscle insertion site.

The importance of the mitral apparatus to the global left ventricular (LV) function has been suggested in several clinical studies. One recent study reported that chordal transsection induced an unloading of myocardium at the papillary muscle insertion site. We hypothesized that the regional response for afterloading at this site with intact mitral apparatus was different from that at the free wall. We investigated the end-systolic pressure-regional segment length relations (ESPLR) in two anterior LV sites, free wall (FREE) and the papillary muscle insertion site (PAP), during an increasing afterload by aortic occlusion in 7 anesthetized open-chest dogs. To measure the regional segment length at FREE and PAP, two sets of the pair of sonomicrometer crystals were implanted in the same midwall depth at the same circumferential hoop by using an echocardiographic guide. ESPLR both at FREE and PAP were always highly linear in a physiological range (r > or = 0.9). The slope of this relation at FREE (274 +/- 164 mmHg/mm) was significantly steeper than that at PAP (157 +/- 118 mmHg/mm) for each dog (p < 0.05). These data indicate that the regional response for afterloading at PAP loaded by chordal tension is different from that at FREE in the same heart.

Factors associated with increased extravascular lung water in cardiac tamponade and myocardial ischemia.

OBJECTIVE: To evaluate and compare the factors associated with pulmonary edema in cardiac tamponade and myocardial ischemia. DESIGN: Prospective, controlled laboratory study. SETTING: Animal research laboratory of a university hospital. SUBJECTS: Fourteen anesthetized dogs. INTERVENTION: Extravascular lung water (EVLW) was measured with thermal indocyanine green dye double-indicator dilution method and hemodynamic indices were determined by the pulmonary artery flotation catheter. Seven dogs were used in the tamponade model, and seven other dogs were used in the myocardial ischemia model. Furthermore, ten dogs were dedicated to measure plasma colloid osmotic pressure (COP) and blood gas analysis during cardiac tamponade and myocardial ischemia. MEASUREMENTS AND MAIN RESULTS: Mean right atrial pressure (MRAP) (7-->10 mm Hg), pulmonary capillary wedge pressure (PCWP) (10-->13 mm Hg), and EVLW (5.4-->10.1 mL/kg) increased during tamponade, but all of these indices returned to the control level after release of tamponade (MRAP, 7 mm Hg; mean PCWP, 11 mm Hg; mean EVLW, 5.2 mL/kg). Myocardial ischemia caused increases in PCWP (10-->14 mm Hg) and EVLW (5.6-->9.6 mL/kg). Although PCWP returned to the control level, EVLW remained elevated (9.2 mL/kg) after reperfusion. EVLW had good correlations with MRAP (r2 = .64, p < .05) and PCWP (r2 = .62, p < .05) during cardiac tamponade. Despite a fair correlation between EVLW and PCWP during ischemia (r2 = .73, p < .05), EVLW was not related to PCWP after reperfusion. COP decreased during myocardial ischemia and at the reperfusion period, but there was no significant change in COP in the cardiac tamponade model. CONCLUSIONS: In contrast to a close relation between hydrostatic pressure and EVLW in cardiac tamponade, hydrostatic pressure was not a determinant of pulmonary edema during the reperfusion period after myocardial ischemia.

Long-term administration of atrial natriuretic peptide in patients with acute heart failure.

A short-term treatment of atrial natriuretic peptide (ANP), a circulating hormone of cardiac origin, is reported to improve cardiac performance in patients with chronic heart failure. However, clinical usefulness of long-term administration of ANP in patients with congestive heart failure has not been reported. We studied 36 patients with severe acute heart failure who resisted various therapy. Hemodynamic parameters were measured before and 48 h after initiating ANP infusion (n = 18) or normal saline (n = 18). Mean pulmonary capillary wedge pressure (23-->13 mm Hg), mean right atrial pressure (10-->5 mm Hg), systemic vascular resistance (2,169-->1,307 dyn x s x cm(-5)) and pulmonary vascular resistance (318-->136 dyn x s x cm(-5)) decreased significantly, whereas cardiac index (1.9-->2.6 L/min/m2) and urine volume (1,692-->2,560 ml/day) increased during long-term ANP infusion (before-->48 h). Moreover, in eight patients with long-term ANP infusion, these hemodynamic effects were maintained at 7 days after initiating ANP infusion. Vasodilating, pulmonary vasorelaxant, and diuretic activities of ANP are maintained without tolerance, and thus long-term ANP infusion is clinically useful in patients with severe acute heart failure.

Role of platelet-activating factor on extravascular lung water after coronary reperfusion in dogs.

Platelet-activating factor (PAF), one of the harmful substances released after coronary reperfusion, has been reported to increase pulmonary vascular permeability and induce pulmonary edema. In this study, we sought to examine the possible role of PAF in the genesis of pulmonary edema after coronary reperfusion. Extravascular lung water (EVLW) was measured by the thermal-dye double indicator dilution method during coronary ligation and after reperfusion in situ in dogs. The proximal left anterior descending coronary artery was occluded for 15 min and reperfused in 5 dogs (group 1), while five other dogs (group 2) were treated with PAF-antagonist (TCV-309, 1 mg/kg) before coronary artery occlusion. EVLW and hemodynamic indices were measured at baseline, 15 min of coronary occlusion, and 15 and 30 min after coronary reperfusion. EVLW increased at 15 min of coronary occlusion in both groups, but there was no significant difference between the two groups (6.4 to 10.3 ml/kg and 5.4 to 7.1 ml/kg in groups 1 and 2, respectively). After coronary reperfusion, EVLW increased further in group 1 (6.4 to 16.5 ml/kg, p < 0.01), but no further increase was observed in group 2 at 30 min after coronary reperfusion. There were no significant differences in hemodynamic indices between the two groups throughout the test. Thus, PAF-antagonist attenuated the increase in EVLW after coronary reperfusion independent of hemodynamic indices, and hence, PAF may play an important role in the genesis of pulmonary edema caused by coronary reperfusion.

Clinical significance of the urinary oxygen tension in patients with ischemic heart disease.

The clinical significance of the urinary oxygen tension (PuO2) was evaluated in 60 patients with ischemic heart disease. The PuO2 had fair relations to cardiac index and serum creatinine level (r = 0.73 and r = 0.73, respectively). Although the PuO2 had a fair relation to serum creatinine in patients with a low cardiac index, there was no relation to the cardiac index. In patients with increases in PuO2 from day 1 to day 2, the cardiac index increased, and the serum creatinine level decreased on the 2nd day, whereas a sustained decrease in cardiac index and an increase in serum creatinine were observed in patients with a decrease in PuO2 from day 1 to day 2. Thus, PuO2 can be used as an indicator of the renal function in patients with ischemic heart disease.

The effects of infusion of trieicosapentaenoyl-glycerol emulsion on extravascular lung water during myocardial ischemia and reperfusion in dogs.

To test the effects of eicosapentaenoic acid (EPA) infusion on pulmonary edema induced by coronary ligation and reperfusion, extravascular lung water (EVLW) was measured in situ by the thermal-dye double indicator dilution method in dogs. In the control group of five dogs, 30 mL of a 10% soybean oil emulsion was infused through a leg vein. One hour after infusion, the left anterior descending coronary artery below the first diagonal branch was ligated for 15 min and then reperfused for 30 min. In the EPA group, six dogs were similarly treated with an emulsion of a 10% trieicosapentaenoyl-glycerol (90% pure). EVLW, pulmonary capillary wedge pressure, mean pulmonary artery pressure, mean blood pressure, and cardiac index were measured before and 15 min after coronary ligation, and 15 min and 30 min after coronary reperfusion. There were no significant differences in the hemodynamic indices between the two groups. EVLW significantly increased up to two times of baseline during coronary ligation in the control group (P < 0.05) and more during reperfusion (P < 0.01), whereas EVLW did not increase in the EPA group. In conclusion, EPA inhibited EVLW accumulation and may be useful for ameliorating one of the ischemia-reperfusion-induced complications, pulmonary edema.

The effect of platelet-activating-factor antagonist TCV-309 on arrhythmias and functional recovery during myocardial reperfusion.

BACKGROUND: We investigated the effects of a platelet-activating-factor antagonist TCV-309, an antagonist of metabolites of ischemia, on arrhythmias and functional recovery during in-situ reperfusion in dogs. METHODS: Open-chest anesthetized dogs were subjected to ligation of the left anterior coronary artery. Ischemia was maintained for 20 min after which reperfusion was allowed. A cardiac surface ECG was recorded continuously with the II limb lead. Monophasic action potential, left ventricular segment shortening measured by sonomicrometer, and left ventricular pressure were recorded simultaneously under atrial pacing (group A, n = 14). In a second group of dogs, TCV-309 (1 mg/kg) was administered before coronary artery occlusion (group B, n = 12). The hearts were constantly paced through the right atrium at 120 beats/min throughout all experiments. Measurements were continuously obtained from before drug administration to 30 min after reperfusion. RESULTS: The 90% repolarization time of monophasic action potentials in group B revealed significant recovery compared with group A until the fifth minute after reperfusion (P < 0.02). Reduction of severe ventricular arrhythmias was observed during reperfusion in group B (P < 0.05). The percentage segment shortening and left ventricular pressure did not differ significantly between the groups. CONCLUSION: The platelet-activating-factor antagonist had beneficial effects on arrhythmias but not on functional recovery during reperfusion after brief coronary artery occlusion in situ in dogs.

Effect of ventriculoarterial coupling on residual left ventricular pump function in diabetic patients with myocardial infarction.

To study the ventriculoarterial coupling in diabetic patients with myocardial infarction (MI), 26 diabetic and 34 nondiabetic patients were investigated using radionuclide angiography in the 3rd week after acute MI. Effective arterial elastance was nearly one half of left ventricular end-systolic elastance in nondiabetic patients. On the other hand, effective arterial elastance was twice left ventricular end-systolic elastance in diabetic patients. These data suggest that a decrease in left ventricular contractility and an increase in effective arterial elastance lead to increased potential energy and decreased work efficiency in diabetic patients.

Effect of gender on the left ventricular diastolic performance during isometric handgrip exercise in normal individuals.

To evaluate the effects of gender and isometric handgrip exercise on left ventricular diastolic function in normal individuals, atrial and rapid filling fraction were investigated using M-mode echocardiography in 35 postmenopausal women and 31 age-matched men. There were no significant differences in heart rate, mean blood pressure, atrial filling fraction, and rapid filling fraction at rest between women and men. When the amount of change in hemodynamic variable during exercise was compared, there were no significant differences in heart rate and mean blood pressure between women and men. But the increase in atrial filling fraction and the decrease in rapid filling fraction were significantly larger in women than in men. These data suggest that left ventricular diastolic function is restricted in postmenopausal women, and left atrial booster pump action is mobilized when afterload is increased during isometric handgrip exercise.

Clinical significance of serum colloid osmotic pressure in relation to pulmonary edema and coronary instability in patients with unstable angina.

Several investigators demonstrated that severe reduction of colloid osmotic pressure (COP) predicts a fatal outcome in patients with cardiopulmonary failure. To evaluate the clinical significance of COP in relation to pulmonary edema, we studied 117 patients with unstable angina admitted in the hospital within 24 h after the chest pain. The mean COP of all 117 patients was 24.8 +/- 3.7 mmHg. COP was significantly lower in patients with pulmonary edema, according to the chest x-ray findings, compared with the patients without it. Among 26 patients with emergency coronary arteriography, a fairly good correlation was observed between coronary jeopardy score and COP (r = -0.57, p less than 0.005). Furthermore, COP in patients who survived 26 months after the hospital discharge was significantly higher than that of the nonsurvivors. Thus, measurement of COP is advised for monitoring patients with unstable angina.