Effects of acute normovolemic hemodilution on ventriculoarterial coupling in dogs

Left Atrial Function Predicts Heart Failure Events in Patients With Newly Diagnosed Left Ventricular Systolic Heart Failure During Short-Term Follow-Up

We assessed the effect of left atrial (LA) function index, LA ejection fraction, LA kinetic energy, and maximal LA volume on 6 months clinical outcome in patients with newly diagnosed systolic heart failure (HF). During a 36-month period, 179 consecutive patients (17% female, mean age 63 ± 14 years) were enrolled. During the follow-up, 46 patients had an event (32% event rate; 15 were fatal). Those with an adverse event were older, had lower creatinine clearance, advanced New York Heart Association stage, higher prevalence of ischemic HF, and lower values for right ventricle systolic wave in the tissue Doppler imaging evaluation, compared with those without an event. Multivariate analysis revealed that LA function and ischemic etiology of HF were the most significant prognostic indicators after index hospitalization. This study reveals the important role of LA function for the short-term prognosis of patients with newly diagnosed systolic HF in sinus rhythm.

Effect of levosimendan on ventriculo-arterial coupling in patients with ischemic cardiomyopathy

BACKGROUND

Levosimendan, a novel calcium sensitizer, enhances myocardial contractility without affecting intracellular calcium concentration. It also dilates peripheral arterial vessels by acting on ATP-dependent K(+) channels. Ventriculo-arterial coupling, the relationship between myocardial contractility and the arterial system, describes the efficiency of the cardiovascular system by analysing the relationship between myocardial contractility expressed by ventricular elastance (E(es)) and arterial elastance (E(a)). The aim of this prospective clinical investigation was to evaluate the effects of levosimendan on ventriculo-arterial coupling in patients with ischemic cardiomyopathy.

METHODS

Fifteen patients with stable angina and left ventricular dysfunction underwent elective coronary surgery. Before surgery started, ventriculo-arterial coupling and several variables of cardiovascular performance were assessed by invasive monitoring and transoesophageal echocardiography before and after administration of levosimendan (12 mug/kg bolus) in coronary patients under general anesthesia.

RESULTS

The cardiac index and ejection fraction increased significantly [from 1.92 +/- 0.4 to 2.1 +/- 0.4 l/min/m(2) (P = 0.0004) and from 31% +/- 6 to 40% +/- 9 (P = 0.001), respectively], while mean arterial pressure and systemic vascular resistances decreased significantly [from 83 +/- 10 to 72 +/- 5 mmHg (P = 0.0016) and from 997 +/- 341 to 855 +/- 324 dyne s/cm(5) (P = 0.0002), respectively]. After administration of levosimendan, E(a) decreased significantly (from 4.3 +/- 1.8 to 3.2 +/- 1.3 mmHg/ml/m(2), P= 0.005), while E(es) significantly increased (from 2.8 +/- 1.6 to 4.4 +/- 2.3 mmHg/ml/m(2), P= 0.05); as a result, E(a)/E(es) decreased significantly (from 1.76 +/- 1 to 0.83 +/- 0.2, P= 0.002).

CONCLUSION

Levosimendan improves ventriculo-arterial coupling and cardiovascular performance in coronary patients with left ventricular dysfunction by enhancing myocardial contractility and reducing arterial elastance.

Cardioprotective effects of acute isovolemic hemodilution in a rat model of transient coronary occlusion*

OBJECTIVES

Following isovolemic hemodilution (AIH), lowering blood viscosity induces acceleration of erythrocyte velocity resulting in improved tissue oxygen delivery. Using a rat model of myocardial infarct, we tested the hypothesis that AIH would attenuate myocardial damage due to transient coronary occlusion.

DESIGN

Prospective, randomized, and controlled animal study.

SETTING

Animal research laboratory in a university hospital.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

All rats were subjected to 30 mins of left coronary artery occlusion followed by 48 hrs of reperfusion. Before the ischemic period, the anesthetized rats were randomly allocated to undergo either 15 mins of waiting (controls) or AIH to achieve a hematocrit of 30% (AIH-CO) by stepwise blood withdrawal and isovolemic compensation with 6% hydroxyethylstarch 200-0.5.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic variables were comparable in the two groups, except for higher indexes of stroke volume in the AIH-CO group. During coronary occlusion and the reperfusion period, AIH resulted in a lower incidence of fatal ventricular tachyarrhythmia (17% vs. 50% in control group, p < .05) and higher survival at 48 hrs of postreperfusion (83% vs. 42%, p < .05).Preischemic hemodilution significantly attenuated myocardial damage as shown by lower release of cardiac troponin I and reduction in myocardial infarct size as measured by tetrazolin staining. Histologic examination revealed no difference regarding peri-ischemic infiltration with neutrophil granulocytes.

CONCLUSIONS

Our data provide the first experimental demonstration that preischemic moderate AIH confers cardioprotection and improves survival in a rat model of myocardial infarct.

Cardiovascular response to acute normovolemic hemodilution in patients with coronary artery diseases: Assessment with transesophageal echocardiography

OBJECTIVE

Preoperative acute normovolemic hemodilution induces an increase in circulatory output that is thought to be limited in patients with cardiac diseases. Using multiple-plane transesophageal echocardiography, we investigated the mechanisms of cardiovascular adaptation during acute normovolemic hemodilution in patients with severe coronary artery disease.

DESIGN

Prospective case-control study.

SETTING

Operating theater in a university hospital.

PATIENTS

Consecutive patients treated with beta-blockers, scheduled to undergo coronary artery bypass (n = 50).

INTERVENTIONS

After anesthesia induction, blood withdrawal and isovolemic exchange with iso-oncotic starch (1:1.15 ratio) to achieve a hematocrit value of 28%.

MEASUREMENTS AND MAIN RESULTS

In addition to heart rate and intravascular pressures, echocardiographic recordings were obtained before and after acute normovolemic hemodilution to assess cardiac preload, afterload, and contractility. In a control group, not subjected to acute normovolemic hemodilution, hemodynamic variables remained stable during a 20-min anesthesia period. Following acute normovolemic hemodilution, increases in cardiac stroke volume (+28 +/- 4%; mean +/- sd) were correlated with increases in central venous pressure (+2.0 +/- 1.3 mm Hg; R = .56) and in left ventricular end-diastolic area (+18 +/- 5%, R = .39). The unchanged left ventricular end-systolic wall stress and preload-adjusted maximal power indicated that neither left ventricular afterload nor contractility was affected by acute normovolemic hemodilution. Diastolic left ventricular filling abnormalities (15 of 22 cases) improved in 11 patients and were stable in the remaining four patients. Despite reduction in systemic oxygen delivery (-20.5 +/- 7%, p < .05), there was no evidence for myocardial ischemia (electrocardiogram, left ventricular wall motion abnormalities).

CONCLUSIONS

In anesthetized patients with coronary artery disease, moderate acute normovolemic hemodilution did not compromise left ventricular systolic and diastolic function. Lowering blood viscosity resulted in increased stroke volume that was mainly related to increased venous return and higher cardiac preload.