Slight Exercise in Ambulatory LVAD Patients Leads to a Severe Compromise of Hemodynamic Parameters

Abstract

PurposeEffects of exercise during LVAD support are still a matter of research. This study aimed to evaluate exercise in this particular patient population by different diagnostic tools in a systematic fashion.Methods and MaterialsAmbulatory patients (n = 9, age 45±13 y, NYHA 2) on LVAD support (Berlin Heart INCOR®, mean support time 465±257d, mean support 4.0±0.3 l/min) on an outpatient basis were exercise evaluated by the means of cycle ergospirometry followed by right heart catheterization during slight cycle exertion (20 watt [W]) through the upper extremity.ResultsThe maximum possible strain over 6±1.2 min during ergospirometry was determined to be 69±13W (35% of normal quota [NQ]). The peak oxygen uptake was 12±2 ml/kg/min (38% NQ). Heart rate increased significantly but not sufficiently from 86±11 beats/min to 125±22 beats/min (69%NQ; p=0.001) during ergospirometry. The arterial lactate concentration increased significantly from 9±2 mg/dl to 40±24 mg/dl (p=0.006). The results of the right heart catheterization on a seating cycle with a controlled 20W strain are depicted in figure 1. In summary, cardiac output increased moderately from 4.7±0.5 l/min to 6.2±1.0 l/min (increase 24%; p = 0.008) at the cost of a 50 % increase in pulmonary wedge pressure (p=0.01), a 40% increase in mean pulmonary artery pressure (p>0.001) and a 55% increase in right atrial pressure (p=0.007) leading to a significant fall in mixed venous saturation from 58±6 % to 32±9 % (p<0.001).ConclusionsDespite left ventricular support slight exercise leads to severe compromise of hemodynamic parameters. Physicians taking care of this patient population must be aware of exertion effects in LVAD patients. Effects of exercise during LVAD support are still a matter of research. This study aimed to evaluate exercise in this particular patient population by different diagnostic tools in a systematic fashion. Ambulatory patients (n = 9, age 45±13 y, NYHA 2) on LVAD support (Berlin Heart INCOR®, mean support time 465±257d, mean support 4.0±0.3 l/min) on an outpatient basis were exercise evaluated by the means of cycle ergospirometry followed by right heart catheterization during slight cycle exertion (20 watt [W]) through the upper extremity. The maximum possible strain over 6±1.2 min during ergospirometry was determined to be 69±13W (35% of normal quota [NQ]). The peak oxygen uptake was 12±2 ml/kg/min (38% NQ). Heart rate increased significantly but not sufficiently from 86±11 beats/min to 125±22 beats/min (69%NQ; p=0.001) during ergospirometry. The arterial lactate concentration increased significantly from 9±2 mg/dl to 40±24 mg/dl (p=0.006). The results of the right heart catheterization on a seating cycle with a controlled 20W strain are depicted in figure 1. In summary, cardiac output increased moderately from 4.7±0.5 l/min to 6.2±1.0 l/min (increase 24%; p = 0.008) at the cost of a 50 % increase in pulmonary wedge pressure (p=0.01), a 40% increase in mean pulmonary artery pressure (p>0.001) and a 55% increase in right atrial pressure (p=0.007) leading to a significant fall in mixed venous saturation from 58±6 % to 32±9 % (p<0.001). Despite left ventricular support slight exercise leads to severe compromise of hemodynamic parameters. Physicians taking care of this patient population must be aware of exertion effects in LVAD patients.