Promising approach for the preclinical assessment of cardiac risks using left ventricular pressure-volume loop analyses in anesthetized monkeys.

INTRODUCTION: Load-independent cardiac parameters obtained from the ventricular pressure-volume relationship are recognized as gold standard indexes for evaluating cardiac inotropy. In this study, for better analyses of cardiac risks, load-independent pressure-volume loop parameters were assessed in addition to load-dependent inotropic, hemodynamic and electrocardiographic changes in isoflurane-anesthetized monkeys. METHODS: The animals were given milrinone (a PDE 3 inhibitor), metoprolol (a ß-blocker), or dl-sotalol (a ß+IKr blocker) intravenously over 10min at two dose levels including clinically relevant doses (n=5/drug). RESULTS: Milrinone and metoprolol produced positive and negative inotropy, respectively. These effects were detected as changes in the slope of the preload-recruitable stroke work, which is a load-independent inotropic parameter. However, dl-sotalol did not alter the slope of the preload-recruitable stroke work. That means dl-sotalol produced no inotropy, although it decreased load-dependent inotropic parameters, including maximal upstroke velocity of left ventricular pressure, attributable to decreased heart rate and blood pressure. Other typical pharmacological effects of the compounds tested were also detected. Both ß-blockers produced PR prolongation, decreased left ventricular end-systolic pressure, increased left ventricular end-diastolic pressure, and increased maximal descending velocity of left ventricular pressure and time constant for isovolumic relaxation. dl-Sotalol also prolonged heart-rate-corrected QT interval. Milrinone induced reflex tachycardia, PR shortening, and decreased left ventricular end-diastolic pressure. DISCUSSION: The overall assessment by not only load-dependent inotropic parameters but also load-independent parameters obtained from the ventricular pressure-volume loop analysis using monkeys can provide further appropriate information for the assessment of drug-induced cardiac risks.

Hemodynamic management and outcome of patients treated for cerebral vasospasm with intraarterial nicardipine and/or milrinone.

BACKGROUND: Vasospasm is a potentially devastating complication after aneurysmal subarachnoid hemorrhage. Although endovascular treatment with intraarterial nicardipine and milrinone is an accepted clinical treatment strategy, there is little information either on hemodynamic management during treatment or on outcome and consequences of the hemodynamic management. We tested 2 hypotheses: (1) intraarterial administration of nicardipine and milrinone to treat cerebral vasospasm would require increased administration of vasoconstrictor to support arterial blood pressure at target levels; and (2) high-dose vasopressors administered to increase blood pressure in these patients would lead to systemic acidosis and end-organ ischemic damage. METHODS: We conducted a single-center, retrospective review of consecutive patients with clinically symptomatic vasospasm after aneurysmal subarachnoid hemorrhage that failed medical management with "triple H therapy" and subsequently received intraarterial nicardipine and/or milrinone between March 2005 and July 2007. RESULTS: Of 160 endovascular interventions in 73 patients (aged 52 +/- 10 years; 50 women), 96 received only nicardipine, 5 only milrinone, and 59 both drugs. General anesthesia with muscle relaxation was performed for 93% of procedures. During treatment, both the number and dose of vasopressors required to maintain arterial blood pressure at target levels increased; the median dose of phenylephrine increased from 200 (n = 121) to 325 microg/min (n = 122), norepinephrine increased from 12 (n = 60) to 24.5 microg/min (n = 87), and vasopressin infusions increased from 7 to 24. Nonetheless, arterial blood pressure decreased 13% during treatment. In >90% of procedures, the postprocedure angiogram showed improved vessel caliber. A single patient demonstrated troponin T increase; no patients had a decrease in renal function, bowel or peripheral ischemia, systemic acidosis, or acute stroke. Overall mortality was 11%. CONCLUSIONS: Intraarterial administration of nicardipine and/or milrinone requires use of vasopressors to maintain arterial blood pressure. Despite high doses of vasoconstrictors, treatment has low mortality, minimal end-organ ischemic damage or systemic acidosis, and results in improved caliber of cerebral vessels affected by vasospasm.