Inhaled epoprostenol (prostacyclin) and pulmonary hypertension before cardiac surgery

Effects of anesthetic induction in patients with diastolic dysfunction

PURPOSE

To evaluate the effects of anesthetic induction on bi-ventricular function in patients with known preoperative left ventricular (LV) diastolic dysfunction undergoing coronary artery bypass grafting surgery (CABG).

METHODS

Fifty patients with diastolic dysfunction undergoing CABG were studied. Preoperative transthoracic echocardiographic (TTE) examination was performed on the day before surgery and transesophageal echocardiography (TEE) assessment was undertaken after induction of anesthesia with sufentanil, midazolam, isoflurane, and pancuronium. Mean arterial pressure (MAP) and heart rate (HR) were recorded. The diameters of the left atrium (LA) and right atrium (RA) and right ventricular (RV) end-diastolic area (EDA), end-systolic area (ESA) and fractional area change (FAC) were obtained from the apical 4-chamber view. The LV EDA, LV ESA and LV FAC were measured from a transgastric midpapillary view. Pulsed wave Doppler of the transmitral flow (TMF) and transtricuspid flow (TTF), pulmonary venous flow (PVF) and hepatic venous flow (HVF) were measured. Mitral (Em, Am) and tricuspid (Et, At) annulus velocities were assessed by tissue Doppler imaging (TDI). Assessment of diastolic dysfunction was graded from normal to severe using a validated score.

RESULTS

Following induction of anesthesia, HR decreased (66 +/- 12 vs 55 +/- 9 beats.min(-1), P < 0.0001) while MAP remained unchanged (86.1 +/- 9.0 vs 85.6 +/- 26.5 mmHg, P = 0.94). The diameters of the LA, RA and RV chambers increased, and these increases were associated with opposite changes in LV dimensions. The RV FAC decreased, but the LV FAC remained unchanged. While most Doppler velocities decreased (P < 0.05), a greater reduction in the atrial components of the TMF, TTF and TDI ratios was observed. The LV diastolic function score improved after induction of anesthesia (100% of patients with a score > or = = 3 pre-induction compared to 58% of patients with a score > or = 3 post-induction; P = 0.0004).

CONCLUSION

In patients with left ventricular diastolic dysfunction, cardiac dimensions and bi-ventricular filling patterns are significantly altered after induction of general anesthesia. These changes can be explained to some extent by a reduction in venous return with general anesthesia, reduced atrial contractility, and the effect of positive pressure ventilation. Although the LV diastolic function score improved after induction of anesthesia, it is difficult to dissociate this effect from that of altered loading conditions.

The right ventricle in cardiac surgery, a perioperative perspective: II. Pathophysiology, clinical importance, and management

The importance of right ventricular (RV) function in cardiovascular disease and cardiac surgery has been recognized for several years. RV dysfunction has been shown to be a significant prognostic factor in cardiac surgery and heart transplantation. In the first article of this review, key features of RV anatomy, physiology, and assessment were presented. In this second part, we review the pathophysiology, clinical importance, and management of RV failure in cardiac surgery.

Treatment of refractory pulmonary arterial hypertension with inhaled epoprostenol in an infant with congenital heart disease

Epoprostenol is a potent arterial vasodilator, and its administration by inhalation localizes its effects to the pulmonary circulation. In this case report, we describe a 3-month-old male patient with significant refractory pulmonary hypertension after pulmonary artery banding and placement of a Blalock-Taussig shunt. This patient continued to have significant hypoxic episodes despite maximal therapy with sedation, alkalinization, sildenafil, and inhaled nitric oxide. After the addition of inhaled epoprostenol, improvements in both clinical response and echocardiography-based hemodynamics were observed. The case supports a synergistic role among the agents in the treatment of pulmonary arterial hypertension from congenital heart disease.

Baseline regional cerebral oxygen saturation correlates with left ventricular systolic and diastolic function

OBJECTIVE

To evaluate the correlation between baseline cerebral oxygen saturation (ScO(2)) and cardiac function as assessed by pulmonary artery catheterization and transesophageal echocardiography (TEE).

DESIGN

A retrospective study.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Cardiac surgery patients.

MEASUREMENTS AND RESULTS

Patients undergoing cardiac surgery with bilateral recording of their baseline ScO(2) using the INVOS 4100 (Somanetics, Troy, MI) were selected. A pulmonary artery catheter was used to obtain their hemodynamic profile. Left ventricular (LV) systolic and diastolic function was evaluated by TEE, after the induction of anesthesia, using standard criteria. A model was developed to predict ScO(2). A total of 99 patients met the inclusion criteria. There were significant correlations between mean ScO(2) values and central venous pressure (CVP) (r = -0.31, p = 0.0022), pulmonary capillary wedge pressure (r = -0.25, p = 0.0129), mean pulmonary artery pressure (MPAP) (r = -0.24, p = 0.0186), mean arterial pressure/MPAP ratio (r = 0.33, p = 0.0011), LV fractional area change (<35, 35-50, and >or=50, p = 0.0002), regional wall motion score index (r = -0.27, p = 0.0062), and diastolic function (p = 0.0060). The mean ScO(2) had the highest area under the receiver operating characteristic curve (0.74; confidence interval, 0.64-0.84) to identify LV systolic dysfunction. A model predicting baseline ScO(2) was created based on LV systolic echocardiographic variables, CVP, sex, mitral valve surgery, and the use of beta-blocker (r(2) = 0.42, p < 0.001).

CONCLUSION

Baseline ScO(2) values are related to cardiac function and are superior to hemodynamic parameters at predicting LV dysfunction.

Milrinone enhances systolic, but not diastolic function during coronary artery bypass grafting surgery

PURPOSE

To evaluate the effect of milrinone on diastolic function during coronary artery bypass grafting surgery (CABG).

METHODS

Fifty patients undergoing CABG were randomized to receive a bolus and infusion of milrinone or placebo before cardiopulmonary bypass (CPB) until skin closure. Hemodynamic and transesophageal echocardiographic measurements of systolic and diastolic function were obtained. Pulsed wave Doppler measurements of the early (E wave) and atrial components (A wave) of the transmitral (TMF) and transtricuspid (TTF) flows, and systolic (S wave), diastolic (D wave) and atrial components (Ar) of the pulmonary (PVF) and hepatic venous blood flow (HVF) velocities were performed. Early and atrial components of the mitral (Em and Am waves) and tricuspid annulus velocities (Et and At waves) were assessed by tissue Doppler imaging (TDI). Assessment of diastolic dysfunction was graded from normal to severe using a scale score.

RESULTS

Cardiac index and heart rate were higher in the milrinone group compared to placebo after the administration of study drug (2.8 +/- 0.6 vs 2.1 +/- 0.5 L.min(-1)m(-2)) (P < 0.0001) and (67 +/- 8 vs 60 +/- 12 beats.min(-1)) (P < 0.05) respectively. There were no changes in left and right ventricular diastolic dysfunction scores between study groups. Higher PVF S wave, HVF S wave, TTF A wave and At measured by TDI in the milrinone group compared with placebo suggested an improvement in ventricular systolic and atrial contraction.

CONCLUSION

Distinct from its effects on systolic function, milrinone administered before CPB is not with associated improved biventricular diastolic function in patients undergoing CABG.

Inhaled milrinone: a new alternative in cardiac surgery?

The administration of milrinone through inhalation has been studied in only a few animal and human studies. Compared to the intravenous administration, inhaled milrinone has been shown to reduce pulmonary artery pressure without systemic hypotension. Therefore, this approach could represent an alternative to nitric oxide. This current state of knowledge of intravenous and inhaled milrinone is presented and summarized.

Left and right ventricular diastolic dysfunction as predictors of difficult separation from cardiopulmonary bypass

PURPOSE

As the evaluation of diastolic function can be complex in the setting of a busy cardiac operating room, its assessment may benefit from an algorithmic approach using transesophageal echocardiography. We developed a diagnostic algorithm which was then applied in a series of cardiac surgery patients to determine whether moderate to severe left ventricular diastolic dysfunction (LVDD) and right ventricular diastolic dysfunction (RVDD) can predict difficult separation from cardiopulmonary bypass (DSB).

METHODS

An algorithm using pulsed-wave Doppler interrogation of the mitral and tricuspid valve, the pulmonary and hepatic venous flow, and tissue Doppler interrogation of the mitral and tricuspid annulus was developed. The study was divided in two phases involving two groups of patients undergoing cardiac surgery. In phase I, echocardiographic evaluations of patients (n = 74) were used to test the reproducibility of the algorithm and to evaluate inter-observer variability using Cohen's kappa values which were calculated in three specific periods. In phase II, the algorithm was applied to a second group of patients (validation group, n = 179) to explore its prognostic significance. The primary end-point in phase II was DSB.

RESULTS

In phase I, the kappa coefficients for LVDD and RVDD algorithms were 0.77 and 0.82, respectively. In phase II, moderate or severe degrees of LVDD were observed in 29 patients (16%) and moderate to severe RVDD was observed in 18 patients (10%) before cardiac surgery. Both moderate and severe LVDD (P = 0.017) and RVDD (P = 0.049) before surgery were observed more frequently in patients with DSB.

CONCLUSION

Moderate and severe LVDD and RVDD can be identified with very good reproducibility, and both degrees of diastolic dysfunction are associated with DSB.

Effects of prostacyclin and milrinone on pulmonary hemodynamics in newborn lambs with persistent pulmonary hypertension induced by ductal ligation

Prostacyclin (PGI(2)) stimulates adenyl cyclase to synthesize cAMP within the vascular smooth muscle resulting in vasodilatation. Milrinone inhibits cAMP clearance by phosphodiesterase type III. We studied the dose response of pulmonary and systemic hemodynamics to intratracheal (IT) PGI(2) in newborn lambs with pulmonary hypertension (PH) and whether intravenous milrinone potentiate these effects. IT-PGI(2) at varying doses was administered to lambs with PH induced by prenatal ductal ligation. IT-PGI(2) doses were repeated in the presence of intravenous milrinone (bolus-100 microg/kg followed by infusion at 1 microg/kg/min). Increasing doses of IT-PGI(2) significantly decreased mean pulmonary arterial pressures (PAP) and pulmonary vascular resistance (PVR) and increased pulmonary blood flow (PBF). Intravenous milrinone by itself produced a significant reduction in PVR and a significant increase in PBF. Intravenous milrinone significantly shortened the onset, prolonged the duration and degree of pulmonary vasodilation produced by PGI(2). We conclude that intravenous milrinone potentiates the pulmonary vasodilator effects of PGI(2) at lower doses.

Importance of relative pulmonary hypertension in cardiac surgery: the mean systemic-to-pulmonary artery pressure ratio

OBJECTIVE

To determine the importance of the mean arterial pressure-to-mean pulmonary artery pressure ratio (MAP/MPAP) in cardiac surgical patients.

DESIGN

Retrospective and prospective studies (3 groups).

SETTING

Tertiary care hospital.

PARTICIPANTS

Cardiac surgical patients (1,557).

INTERVENTION

Retrospective analysis (group 1), induction of general anesthesia (group 2), and transesophageal Doppler echocardiography (group 3).

MEASUREMENTS AND MAIN RESULTS

In group 1 (n = 1,439), demographic, hemodynamic, and other perioperative variables were collected with follow-up until hospital discharge. The primary outcome was a composite index of hemodynamic complications that included death, resuscitated cardiac arrest, use of vasopressive drugs for >24 hours postoperatively, or the use of an intra-aortic balloon pump that was not present preoperatively. In group 2 (n = 34), the effect of general anesthesia on the MAP/MPAP ratio was studied, and Doppler echocardiography was used to evaluate diastolic profiles in group 3 (n = 74). In group 1, a total of 302 patients experienced hemodynamic complications (21%). The MAP/MPAP ratio was significantly lower in the patients who developed complications (3.3 +/- 1.3 v 4.0 +/- 1.4, p < 0.0001). Multiple stepwise logistic regression analysis showed the MAP/MPAP ratio to be an independent predictor of hemodynamic complications (p < 0.0001). In group 2, the induction of anesthesia decreased both MAP and MPAP, but the ratio remain unchanged (p = 0.242). In group 3, patients with moderate-to-severe diastolic dysfunction (DD) had a lower ratio (3.5 +/- 0.9 v 4.0 +/- 1.1 compared with those with normal-to-mild DD, p = 0.07).

CONCLUSION

The MAP/MPAP ratio is a useful hemodynamic variable in cardiac surgery. It can be used to predict hemodynamic complications after cardiac surgery, is not influenced by the induction of anesthesia, and tends to correlate with the severity of left ventricular diastolic profiles.

Incidence and significance of abnormal hepatic venous Doppler flow velocities before cardiac surgery

OBJECTIVE

The purpose of this study was to determine the incidence and significance of abnormal hepatic Doppler venous flow velocities as signs of an abnormal right ventricular filling pattern before cardiac surgery.

DESIGN

Retrospective and prospective validation study.

SETTING

Tertiary care hospital.

PARTICIPANTS

Cardiac surgical patients (121 patients).

INTERVENTIONS

Not applicable.

MEASUREMENTS

Demographic, hemodynamic, and echocardiographic variables; vasoactive support; and difficult separation from bypass were compared between patients with or without abnormal hepatic venous Doppler flow. Logistic regression analysis was performed to identify predictors of difficult separation from bypass. Abnormal hepatic venous flow was observed in 23 (29%) and 17 patients (41%) in the retrospective and prospective study. Abnormal hepatic venous flow before surgery was associated with more vasoactive support in both the retrospective (p = 0.0362) and prospective study (p = 0.0163). In the prospective study, abnormal hepatic venous flow was associated with a higher Parsonnet score (p = 0.0005), more atrial fibrillation (p < 0.0001), pacemaker requirement (p = 0.0124), mitral valve replacement (p = 0.0325), reoperation (p = 0.0050), lower mean arterial pressure to pulmonary artery pressure ratio (p = 0.0127), higher wall motion score index (p = 0.0491), and higher incidence of abnormal right ventricular systolic function (p = 0.0139). Abnormal hepatic venous flow was not found to be an independent predictor of difficult separation from bypass.

CONCLUSIONS

Abnormal hepatic venous flow velocities before cardiac surgery are frequent and are associated with increased need for vasoactive support after cardiopulmonary bypass. However, it is not an independent predictor of difficult separation from bypass and worse outcome.

Prostacyclin for pulmonary hypertension in adults

BACKGROUND

Primary pulmonary hypertension (PPH) is progressive, resulting in right ventricular failure. Pulmonary hypertension can be idiopathic or associated with other conditions. Prostacyclin is a potent vasodilator and inhibitor of platelet aggregation, and can be given orally, subcutaneously, intravenously or inhaled via a nebuliser.

OBJECTIVES

To determine the efficacy of prostacyclin or one of its analogues in idiopathic primary pulmonary hypertension.

SEARCH STRATEGY

Electronic searches were carried out with pre-specified terms. Searches were current as of July 2004.

SELECTION CRITERIA

Two reviewers selected randomised controlled trials (RCTs) involving adults with pulmonary hypertension for inclusion.

DATA COLLECTION AND ANALYSIS

Study quality was assessed and data extracted independently by two reviewers. Outcomes were analysed as continuous and dichotomous outcomes. We sub-grouped data where possible by aetiology of PH (PPH, PH secondary to connective tissue disorder or mixed populations).

MAIN RESULTS

Nine RCTs of mixed duration (3 days-52 weeks), recruiting 1175 participants were included (NYHA functional classes II-IV). Intravenous prostacyclin versus usual care (four studies): There were significant improvements in exercise capacity of around 90 metres, cardiopulmonary haemodynamics and NYHA functional class over 3 days-12 weeks. Effects were consistent in primary and secondary pulmonary hypertension. Oral prostacyclin versus placebo (two studies): Short-term data (3-6 months) indicated that there was a significant improvement in exercise capacity, but data from one study of 52 weeks reported no significant difference at 12 months. No significant differences were observed for any other outcome. Subcutaneous treprostinil versus placebo (two studies, 8-12 weeks):One large study reported a significant median improvement in exercise capacity of around 16 metres. Cardiopulmonary haemodynamics and symptom scores favoured treprostinil. Infusion site pain and withdrawals due to adverse events were more frequent with treprostinil. Inhaled prostacyclin versus placebo (one study, 12 weeks):There was a significant increase in exercise capacity of approximately 36 metres. Treatment led to better symptom scores and functional class status than with placebo. Subgroup analyses reported by individual studies showed a better exercise capacity in participants with PPH, than those participants with PH secondary to other diseases. Side effects and adverse events were common in the studies.

AUTHORS' CONCLUSIONS

There is evidence that intravenous prostacyclin in addition to conventional therapy at tolerable doses optimised by titration, can confer some short-term benefits (up to 12 weeks of treatment) in exercise capacity, NYHA functional class and cardiopulmonary haemodynamics. There is also some evidence that patients with more severe disease based upon NYHA functional class showed a greater response to treatment.

Inhaled prostacyclin reduces cardiopulmonary bypass-induced pulmonary endothelial dysfunction via increased cyclic adenosine monophosphate levels

OBJECTIVE

Cardiopulmonary bypass triggers a systemic inflammatory response that alters pulmonary endothelial function, which can contribute to pulmonary hypertension. This study was designed to demonstrate that inhaled prostacyclin, a selective pulmonary vasodilator prostaglandin, prevents pulmonary arterial endothelial dysfunction induced by cardiopulmonary bypass.

METHODS

Three groups of Landrace swine were compared: control without cardiopulmonary bypass (control group); 90 minutes of normothermic cardiopulmonary bypass (bypass group); 90 minutes of cardiopulmonary bypass and treated with prostacyclin during cardiopulmonary bypass (continuous nebulization with continuous positive airway pressure until the end of the cardiopulmonary bypass; prostacyclin group). After 60 minutes of reperfusion, swine were put to death and pulmonary arteries harvested. After contraction to phenylephrine, endothelium-dependent relaxation to bradykinin and acetylcholine was studied in standard organ chamber experiments. The pulmonary artery intravascular cyclic adenosine monophosphate content was compared between the 3 groups (post-cardiopulmonary bypass).

RESULTS

There was a statistically significant improvement of the endothelium-dependent relaxation to bradykinin in the prostacyclin group when compared with the bypass group (P <.05). There was no statistically significant difference for endothelium-dependent relaxation to acetylcholine (P >.05) between the prostacyclin and the bypass groups. There was a statistically significant decrease in the cyclic adenosine monophosphate content and a statistically significant increase of the mean pulmonary artery pressure in the bypass group only (P <.05).

CONCLUSION

Prophylactic use of inhaled prostacyclin has a favorable impact on the pulmonary endothelial dysfunction induced by cardiopulmonary bypass associated with preservation of pulmonary intravascular cyclic adenosine monophosphate content and the pulmonary vascular tone.

Poor correlation between hemodynamic and echocardiographic indexes of left ventricular performance in the operating room and intensive care unit

OBJECTIVES

To compare hemodynamic and echocardiographic indexes of left ventricular performance.

DESIGN

Retrospective database analysis of four clinical trials.

SETTING

University hospital.

PATIENTS

Cardiac surgery patients.

INTERVENTION

Left ventricular performance was evaluated using left ventricular stroke work index (LVSWI) calculated from the pulmonary artery catheter and both fractional area change and regional wall motion score index (RWMSI) measured from transesophageal echocardiography. Measures of left ventricular performance were obtained before and after bypass (group 1, n = 30), during acute increase and decrease in preload (group 2, n = 14), after administration of inhaled prostacyclin or placebo in patients with pulmonary hypertension (group 3, n = 20), and in hemodynamically unstable patients in the intensive care unit at admission and at 2 and 4 hrs (group 4, n = 20).

MAIN RESULTS

A total of 186 simultaneous LVSWI, fractional area change, and RWMSI were analyzed and compared. Patients with RWMSI <1.3 had a LVSWI of 23.4 +/- 10.3 g.m.m compared with 18.4 +/- 7.2 g.m.m in those with RWMSI >1.3 (p =.0349). Subdividing fractional area change into three different groups (> or =50%, 25% to 49%, and < or =24%), the corresponding values of LVSWI were 22.3 +/- 9.7 g.m.m, 22.2 +/- 10.8 g.m.m, and 17.7 +/- 5.5 g.m.m, respectively (p =.5114). Correlations between LVSWI and RWMSI changes ranged from -0.28 to 0.16 (p values from.31 to.94). Correlations between LVSWI and fractional area change changes ranged from -0.62 to 0.22 (p values from.07 to.95).

CONCLUSION

There is a significant discrepancy and limited relationship between the hemodynamic and echocardiographic evaluation of left ventricular performance.