Background: If invasive measurement of arterial blood pressure is not warranted, finger cuff technology can provide continuous and noninvasive monitoring. Finger and radial artery pressures differ; Nexfin (BMEYE, Amsterdam, The Netherlands) measures finger arterial pressure and uses physiologic reconstruction methodologies to obtain values comparable to invasive pressures. Methods: Intra-arterial pressure (IAP) and noninvasive Nexfin arterial pressure (NAP) were measured in cardiothoracic surgery patients, because invasive pressures are avail-

Patients on continuous flow left ventricular assist devices (cf-LVADs) are able to return to an active lifestyle and perform all sorts of physical activities. This study aims to evaluate exercise hemodynamics in patients with a HeartMate II cf-LVAD (HM II). Thirty (30) patients underwent a bicycle exercise test. Along with exercise capacity, systemic cardiovascular responses and pump performance were evaluated at 6 and 12 months after HM II implantation. From rest to maximum exercise, heart rate increased from 87 ± 14 to 140 ± 32 beats/minute (bpm) (P<0.01), while systolic arterial blood pressure increased from 93 ± 12 to 116 ± 21 mm Hg (P<0.01). Total cardiac output (TCO) increased from 4.1 ± 1.1 to 8.5 ± 2.8 L/min (P<0.01) while pump flow increased less, from 5.1 ± 0.7 to 6.4 ± 0.6 L/min (P<0.01). Systemic vascular resistance (SVR) decreased from 1776 ± 750 to 1013 ± 83 dynes.s/cm(5) (P<0.001) and showed the strongest correlation with TCO (r= -0.72; P<0.01). Exercise capacity was affected by older age, while blood pressure increased significantly in men compared with women. Exercise capacity remained consistent at 6 and 12 months after HM II implantation, 51% ± 13% and 52% ± 13% of predicted VO2 max for normal subjects corrected for age and gender. In conclusion, pump flow of the HM II may contribute partially to TCO during exercise, while SVR was the strongest determinant of TCO.

Noninvasive blood pressure measurements are difficult when arterial pulsations are reduced, as in patients supported by continuous flow left ventricular assist devices (cf-LVAD). We evaluated the feasibility of measuring noninvasive arterial blood pressure with the Nexfin monitor during conditions of reduced arterial pulsatility. During cardiopulmonary bypass(CPB) in which a roller pump based or a centrifugal pump based heart-lung machine generated arterial blood pressure with low pulsatility, noninvasive arterial pressures (NAP)measured by the Nexfin Monitor were recorded and compared with invasively measured radial artery pressures (IAP).We also evaluated NAP in 10 patients with a cf-LVAD during a pump speed change procedure (PSCP). During CPB in 18 patients, the NAP-IAP average difference was -1.3 +/- 6.5 mmHg. The amplitude of pressure oscillations were 4.3 +/- 3.8 mmHg measured by IAP. Furthermore, in the cf-LVAD patients, increase in pump speed settings led to an increase in diastolic and mean arterial pressures (MAP) while the NAP acquired a sinusoidal shape as the aortic valve become permanently closed. In conclusion, NAP was similar to IAP under conditions of reduced arterial pulsatility. The device also measured the blood pressure waveform noninvasively in patients supported by a cf-LVAD.