Rapid fall in elevated plasma atrial natriuretic peptide levels after successful catheter balloon valvuloplasty of mitral stenosis

Natriuretic Peptides in Cardiac Anesthesia and Intensive Care

Natriuretic peptides, predominantly B-type, are widely used in cardiology as prognostic and diagnostic biomarkers or, much less often, as a substantive treatment tool. They are hormones that are produced mainly in the myocardium in response to overload and ischemia, and their level quite accurately reflects the degree of myocardial dysfunction. Although their use in cardiac anesthesia and intensive care setting seems to be very beneficial for assessing the risk of acute disturbance of myocardial function or its laboratory monitoring, the actual significance of natriuretic peptides in this area is not yet recognized. This is due to the lack of clear diagnostic and prognostic values for these biomarkers supported by high-quality researches. On the basis of the available data, main advantages, existing difficulties, and most effective ways of using natriuretic peptides for determining the risk of heart surgery and assessing the severity of sepsis, pneumonia, and other critical conditions have been discussed in this review. In addition, the expediency of using natriuretic peptides as target parameters for goal-oriented therapy and as a substantive tool for treatment is considered.

The Atrial Natriuretic Peptide and Its Relation to Hemodynamic and Laboratory Values in Mitral Valve and Coronary Surgery

In 22 patients who underwent mitral valve replacement (13) or coronary bypass surgery (9), preoperative and postoperative plasma atrial natriuretic peptide (p-ANP) concentration, hemodynamic changes, plasma aldosterone, and twenty-four-hour urine sodium-potassium concentrations were studied.

Preoperative ANP levels were 261±172 pg/mL in mitral valve replacement (MVR) and 68±22 in coronary artery bypass grafting (CABG); control levels were 15±4.7 (p < 0.001).

After the induction of anesthesia, ANP levels decreased to 154.5±96.7 pg/mL in MVR and 51±17.5 in CABG (p < 0.01) patients. In the early postop erative period ANP increased to 332±217 pg/mL in MVR and to 94.3 ± 29.7 in CABG (p < 0.001).

In the late postoperative period, the p-ANP of both groups returned to nor mal levels (16 ± 8.05, 11.2 ± 2.82 pg/mL, respectively).

Negative correlations were detected in both MVR and CABG groups be tween p-ANP, p-aldosterone (p < 0.001), p—ANP—cardiac output (p < 0.001), and p—ANP—cardiac index (p < 0.001).

Natriuretic peptides in heart valve disease

Synthesis and release of B-type natriuretic peptide (BNP) are increased in heart failure, and plasma concentrations provide important therapeutic and prognostic information. Recent studies have shown that BNP concentrations are also increased with disease of the mitral and aortic valves. The extent of the increase is broadly related to the severity of the valve abnormality and the degree of consequent cardiac remodelling. BNP concentrations appear to relate to prognosis in these patients and might have a role in identifying suitable candidates for cardiac surgery. This paper reviews the current literature and identifies areas where further research is required if assessment of BNP is to be of practical use.

Endogenous nitric oxide production and atrial natriuretic peptide biological activity in infants undergoing cardiac operations

OBJECTIVES

To examine whether preoperative heart failure and cardiac surgery influence nitric oxide production and atrial natriuretic peptide (ANP) biological activity in infants and whether nitric oxide and ANP participate in the control of postoperative pulmonary vascular tone.

DESIGN

Prospective, clinical study.

SETTING

Tertiary pediatric cardiac intensive care unit in a referral cardiosurgical center.

PATIENTS

Nineteen infants (median age 4 months) undergoing cardiac surgery: 13 infants with ventricular or atrioventricular septal defect associated with heart failure and pulmonary hypertension (group 1); and six infants with tetralogy of Fallot, without heart failure (group 2).

INTERVENTIONS

Blood samples obtained from indwelling catheters or bypass circuit outlets.

MEASUREMENTS AND MAIN RESULTS

Nitrite and nitrate blood concentrations (as a marker for nitric oxide synthesis) and the molar ratio of cyclic guanosine 3',5'-monophosphate (cGMP) to ANP (as a marker for ANP biological activity) were determined before, during, and up to 24 hrs after cardiopulmonary bypass (CPB). In group 1 patients, these biological parameters were related to postoperative pulmonary arterial pressure. Preoperative nitrite and nitrate concentrations were higher in group 1 patients than in group 2 patients (p < .02), and this difference persisted during CPB. Nitrite and nitrate concentrations 24 hrs postoperatively were lower than preoperative values in group 1 patients (p < .05) and were unchanged in group 2 patients. An inverse correlation was observed postoperatively between nitrite and nitrate concentrations and systolic pulmonary arterial pressure (r2 = 0.4, p < .05). Group 1 patients had a lower preoperative cGMP/ANP ratio than group 2 patients (p < .05), despite higher ANP levels (p < .005). The cGMP/ANP ratio decreased during CPB in both groups (p < .0001), and in group 2 patients, cGMP and ANP values remained below preoperative values < or = 24 hrs postoperatively. A correlation was observed between ANP levels and systolic pulmonary arterial pressure 2 and 4 hrs postoperatively (r2 = .4, p < .05, respectively), but no correlation was observed between ANP biological activity and postoperative pulmonary arterial pressure.

CONCLUSIONS

Infants with heart failure and pulmonary hypertension have increased nitric oxide synthesis and decreased ANP biological activity; both phenomena may be involved in the pathophysiology of this clinical condition. CPB has no detectable effect on nitric oxide production but does decrease ANP biological activity. In patients with preoperative heart failure and pulmonary hypertension, endogenous nitric oxide appears to play a role in the control of postoperative pulmonary vascular tone.

Relationship between plasma atrial and brain natriuretic peptide concentration and hemodynamic parameters during percutaneous transvenous mitral valvulotomy in patients with mitral stenosis

Brain natriuretic peptide (BNP), a family of peptides with structural and biologic homologies to previously identified atrial natriuretic peptide (ANP), has been found in human cardiac tissue and plasma. To examine the secretion mechanism of these peptides, we have studied the relationship between their plasma concentrations and hemodynamic parameters before and at 0.5 and 24 hours after percutaneous transvenous mitral commissurotomy (PTMC) in 14 patients with mitral stenosis. We have also investigated the validity of measuring plasma natriuretic peptides as a means for estimating changes in hemodynamic parameters after PTMC. The procedure decreased left atrial pressure (p < 0.01) with an elevation in left ventricular end-diastolic pressure (p < 0.05). Plasma ANP levels decreased significantly after PTMC (before, 64.1 +/- 33.7 fmol/ml; at 0.5 hour, 58.9 +/- 27.7 fmol/ml; at 24 hours, 45.7 +/- 18.3 fmol/ml; p < 0.01), whereas plasma BNP levels remained unchanged after the procedure (before, 5.3 +/- 1.5 fmol/ml; at 0.5 hour, 5.6 +/- 1.9 fmol/ml; at 24 hours, 5.0 +/- 1.9 fmol/ml; p = NS). There was a significant relationship between basal plasma ANP and left atrial pressure (r = 0.88; p < 0.001), and changes in plasma ANP were correlated with those in left atrial pressure (r = 0.69; p < 0.01). Basal plasma BNP was significantly correlated with basal left ventricular end-diastolic pressure (r = 0.65; p < 0.05) but not with the other measured hemodynamic parameters or with plasma volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of atrial natriuretic peptide and vasopressin during retrograde mitral valvuloplasty

Acute mitral obstruction may lead to an increase in atrial natriuretic peptide (ANP) due to increased atrial pressure and a large increase in arginine vasopressin (AVP) due to simultaneous arterial and ventricular baroreceptor unloading. We measured ANP and AVP concentration after transseptal puncture and during percutaneous retrograde mitral balloon valvuloplasty (PRMV) in 11 patients (mean age 57 +/- 12 years; nine women) with mitral stenosis and congestive heart failure. Atrial septal puncture per se resulted in a significant increase in ANP and AVP without a significant change in aortic pressure. Subsequent PRMV led to a further increase in ANP, a transient decrease in aortic pressure from 89 +/- 7 to 45 +/- 4 mm Hg, and a large (fivefold) increase in AVP. ANP and AVP were no longer different from baseline values 18 to 24 after the procedure. This study suggests that transseptal puncture and acute mitral obstruction are major stimuli to ANP release and that combined unloading of arterial and left ventricular mechanoreceptors is a very potent vasopressinergic stimulus.

Atrial natriuretic peptide and vasopressin during percutaneous transvenous mitral valvuloplasty and relation to renin-angiotensin-aldosterone system and renal function

To study the relation between plasma atrial natriuretic peptide (ANP) and cardiac pressure, and to assess the pathophysiologic significance of ANP in water and electrolyte metabolism, the changes in plasma levels of ANP and arginine vasopressin (AVP) were examined in 11 patients with mitral stenosis who underwent percutaneous transvenous mitral valvuloplasty, and compared with the changes in the renin-angiotensin-aldosterone system and renal function. Immediately after valvuloplasty, plasma ANP levels decreased significantly with a concomitant decrease in mean pressures in the left atrium, the pulmonary artery and the right atrium. Plasma ANP levels decreased to the normal range in 4 of the 6 patients with normal sinus rhythm, while all 5 patients with atrial fibrillation had higher levels despite a similar degree of decrease in atrial pressure. There were significant positive correlations between plasma ANP levels and the mean left atrial pressure (r = 0.61, p less than 0.01), the mean pulmonary arterial pressure (r = 0.49, p less than 0.01) and the mean right atrial pressure (r = 0.54, p less than 0.01). The mean plasma AVP levels, on the other hand, showed a transient increase after valvuloplasty from 0.5 +/- 0.1 to 1.2 +/- 0.4 pg/ml (p less than 0.05). The mean plasma renin activity (1.3 +/- 0.3 vs 2.7 +/- 0.8 ng/ml/hr, p less than 0.05) and plasma aldosterone concentration (8.6 +/- 2.3 vs 17.2 +/- 5.2 ng/dl, p less than 0.05) also increased significantly 30 minutes after valvuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Baseline and post-atrial pacing release of atrial natriuretic factor in mitral stenosis

To investigate the release of atrial natriuretic factor (ANF) in mitral stenosis and the influence of the increase on the frequency of atrial contraction or atrial distention on ANF secretion, we studied 10 patients with symptoms of congestive heart failure (New York Heart Association classes II and III) in sinus rhythm, who were undergoing cardiac catheterization as part of an evaluation workup for mitral stenosis. Echocardiographic tracings, repeat determinations of mean pulmonary artery wedge pressure (MPAWP) and mean right atrial pressure, and blood sampling from the pulmonary artery for measurements of ANF were performed at baseline, during atrial pacing (pacing rate of 125 beats/min for 5 minutes), and 5 minutes after the pacing protocol was completed. Baseline ANF levels were closely related to right atrial pressure (r = 0.89; p less than 0.001) and increased markedly after atrial pacing from 205.6 +/- 39.8 (SEM) to 343.9 +/- 57.9 (SEM) pg/ml. A similar pacing-induced increase was shown for MPAWP and left atrial size. Our data indicate that pacing-induced increases in atrial distention and intracavitary pressure further stimulate release of ANF. However, an independent effect of frequency of atrial pacing on plasma ANF in humans could not be identified.