XML Template (2014) [6.11.2014–1:31pm] //blrnas3.glyph.com/cenpro/ApplicationFiles/Journals/SAGE/3B2/CPRJ/Vol00000/140155/APPFile/SG-CPRJ140155.3d
(CPR)
[1–7] [PREPRINTER stage]
EURO PEAN SO CIETY O F CARDIOLOGY ®
Original scientific paper
Safety and efficacy of cardiac rehabilitation for patients with continuous flow left ventricular assist devices
European Journal of Preventive Cardiology 0(00) 1–7 ! The European Society of Cardiology 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/2047487314558772 ejpc.sagepub.com
Christiane Marko1, Georg Danzinger2,3, Michael Ka¨ferba¨ck2,3, Thomas Lackner1, Rudolf Mu¨ller4, Daniel Zimpfer3,5, Heinrich Schima2,3,5 and Francesco Moscato2,3
Abstract Background: Despite the increasing use of left ventricular assist devices (LVADs) in terminal heart failure, cardiac rehabilitation protocols have not yet been documented in larger LVAD patient cohorts. The aim of this study was to investigate safety and efficacy of exercise training during a rehabilitation programme after post-operative discharge of LVAD patients. Methods: Rehabilitation data obtained between 2010–2012 from 41 LVAD patients (mean age 54.8 11.6 years; 20% female) were retrospectively analysed. The exercise protocol consisted of strength exercises for lower limbs, bicycle ergometry, walking and gymnastics. The numbers of training sessions, their duration and intensity as well as adverse events were documented. Spiroergometry was performed at least once and twice in a subgroup of 15 patients (at the beginning and end of rehabilitation). Results: Rehabilitation started 48 38 days post LVAD implantation with an average duration of 32 6 days. An increase in exercise capacity was observed. Duration (19 4 vs 14 2 min, p < 0.001) and intensity of bicycle ergometry increased (module number 6.2 2.8 vs 2.0 1.9, p < 0.001) as well as muscular strength all muscle groups trained (e.g. 33.6 15.2 vs 26.6 11.9 kg at the leg press, p ¼ 0.002). Spiroergometry revealed an increase of maximal oxygen consumption (14.5 5.2 vs 11.3 4.1 ml/min/kg, p ¼ 0.007) in the subgroup that underwent two examinations. In the whole population the average increase was lower (12.81 4.35 ml/min/kg). One training-related adverse event (nonsustained ventricular tachycardia) was observed. Conclusion: Exercise training for LVAD patient as part of a multidisciplinary rehabilitation programme is effective and safe. This warrants the broad application of exercise training after LVAD implantation.
Keywords Continuous flow left ventricular assist devices, cardiac rehabilitation, exercise capacity, exercise training Received 22 July 2014; accepted 16 October 2014
Introduction
1
Rehabilitation Center Felbring, Austria Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria 3 Ludwig Boltzmann Cluster for Cardiovascular Research, Austria 4 Pensionsversicherungsanstalt, Austria 5 Department of Cardiac Surgery, Medical University of Vienna, Austria 2
The implantation of continuous-flow left ventricular assist devices (LVADs) has become an established treatment for patients with end-stage heart failure.1,2 Current guidelines recommend LVAD implantation in selected end-stage heart failure patients both as a bridge to heart transplant (Class I, Level B) and as permanent implant (Class IIa, Level B).3 LVAD therapy allows an enhanced mobility in patient daily life in an increasing
Corresponding author: Christiane Marko, Rehabilitationszentrum Felbring der Pensionsversicherungsanstalt, Felbring 71, 2723 Muthmannsdorf, Austria. Email: [email protected]
Downloaded from cpr.sagepub.com at UNIV OF LETHBRIDGE on October 16, 2015
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(CPR)
[1–7] [PREPRINTER stage]
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European Journal of Preventive Cardiology 0(00)
number of patients and over longer periods of implant duration; exercise therapy thus contributes to an overall improvement in quality of life. However the numerous studies investigating cardiac rehabilitation and its benefit after heart transplantation,4 have not yet, in large patient cohorts, been extended to LVAD patients. To the authors’ knowledge there are very few reports5–10 about the safety and effectiveness of cardiac rehabilitation in LVAD patients. In particular, cardiac rehabilitation has not been evaluated when performed on a routine clinical basis involving all patients receiving an LVAD, including even the more critical ones. The present study seems therefore to be the first that assesses a stationary and structured cardiac rehabilitation programme involving exercise training of LVAD patients early after hospital discharge. The rehabilitation programme assessed here was aimed, first, to achieve patient independence and mobility in daily life and confidence in handling the assist device peripherals and then, to provide an overall improvement in the physical conditioning and therefore quality of life. Due to the complex interaction between a continuousflow LVAD and the patient haemodynamics, questions related to safety and efficacy of cardiac rehabilitation, especially in more critical patients, were expected and did arise.
Materials and methods Patient data from consecutive patients who had a ventricular assist device implanted at the General Hospital in Vienna from 1 February 2010–1 March 2012, were considered. Patients were included in the analysis if they underwent at least 21 consecutive days of rehabilitation from 1 March 2010–1 April 2012. Paediatric patients or those with a biventricular assist device (BiVAD) were excluded from the analysis. Since in Austria cardiac rehabilitation is funded by the government, nobody was excluded because of financial issues. Data collection and analysis were approved by the Institutional Review Board of Lower Austria.
Diagnostic tests Baseline examinations at the time of admission to the rehabilitation centre included echocardiography and electrocardiography (ECG) in all patients and, in patients rated stable enough, a cardiopulmonary stress test. At the end of rehabilitation a cardiopulmonary stress test was again performed in those patients rated stable enough. The loading protocol for the cardiopulmonary stress test was adapted to the estimated workload of the patient and a duration of the test was varied from 8–12 min.
Rehabilitation programme and the medical training therapy If patients were haemodynamically stable, which meant that during early mobilisation no clinical signs of orthostatic dysregulation, hypovolaemia, infections as well as no low-flow and suction alarms were observed, the medical training therapy could be initiated. It consisted of strength as well as endurance training together with walking and gymnastics, according to the exercise recommendation for patients suffering from heart failure.11 To determine the intensity of the training sessions the perceived level of exertion according to the Borg scale12 was used. An exertion of somewhat hard intensity (grade 13 in the Borg scale) was aimed for. This intensity corresponds to training between the anaerobic threshold and the respiratory compensation point.13 Usual methods for continuously monitoring the intensity of training could not be used, e.g. arterial blood pressure was not measurable using an automatic oscillometric system because of the low arterial pressure pulsatility characteristic of patients with continuous flow LVADs.14 The measurement of arterial blood pressure was only performed before and after the training sessions. The patient did not start the exercise training if a blood pressure higher than 90 mm Hg15 was observed. Strength training was directed to muscle groups of the lower extremities (leg press, leg extensor, leg flexor, lower limb abductor, lower limb adductor) with two series of 12 repetitions each. Special care was taken to avoid forced respiration during exercise. Aerobic training consisted of bicycle ergometry, using an interval training schema that included continuous ECG monitoring. Interval training has been employed previously for patients with chronic heart failure16 and consists of alternating periods of high and low intensity in order to increase time spent at a high effort and to stimulate cardiovascular and muscular adaptation more strongly. Twelve modules of increasing intensity (coded B1–B12, see Table 1) were standardised. The training protocol included 3 min bicycling with no load at the beginning and at the end of the session to warm up and cool down. Walking training was performed in groups of patients having approximately the same physical capabilities. There were five different groups that walked along paths covering different distances and elevations in different amounts of time (W1–W5, see also Table 1). Gymnastic training was organised in groups as well as in individual sessions. Five different groups performed different kinds of exercises (coordination, strength and balance training) in different intensity grades and body positions (G1–G5 as described in Table 1). Patients were assigned to their groups
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XML Template (2014) [6.11.2014–1:31pm] //blrnas3.glyph.com/cenpro/ApplicationFiles/Journals/SAGE/3B2/CPRJ/Vol00000/140155/APPFile/SG-CPRJ140155.3d
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Table 1. Rehabilitation training schema.
Acquired data and statistical analysis
Load phase (W)
Recovery/load phase duration (s)
Bicycle ergometry training B1 1 B2 1 B3 1 B4 5 B5 5 B6 5 B7 5 B8 10 B9 10 B10 10 B11 10 B12 10
5 15 20 25 25 30 40 50 60 70 90 120
60/30 60/20 60/30 60/20 60/30 60/20 60/20 60/20 60/20 60/20 60/20 60/20
Group
Distance (km)
Elevation (m)
Module
Recovery phase (W)
Duration (min)
Walking training W1 30 W2 30 W3 45 W4 60 W5 90
0.6 1.0 1.6–2.0 2.2–2.8 4.5–5.5
0 0 30 60 130
Group
Body position
Gymnastic G1 G2 G3 G4 G5
training Sitting on a chair with a seatback Sitting on a chair with no seatback Standing and sitting Lying, standing and sitting Any body position
according to the underlying cardiac illness, age and, as needed, specific orthopaedic problems and/or postoperative limitations. For this class of training, the aim was to change to a better-performing group. Individual gymnastics were aimed at training coordination, balance and strength, especially of respiratory muscles, depending on the individual patient needs. Throughout the rehabilitation period, patients were closely followed to detect early signs of decompensation or hypovolaemia. Our pharmacological treatment was aimed at increasing the dosage of angiotensin converting enzyme (ACE) inhibitor and/or b-blocker medication in very low steps although the patients were stable as it is recommended for heart failure and also for LVAD patients.3,15 Criteria for interrupting the training were pain (especially localised in the thorax), ventricular arrhythmias, haemodynamic instability (pump low-flow alarm, suction alarm, dizziness), subjective exhaustion and neurologic symptoms.
The number of training sessions performed by each patient was documented during through the whole rehabilitation period. In particular, changes in lifted weight for strength training, changes in training intensity and duration for the bicycle ergometry, and training and changes of group in walking and gymnastic training were recorded. Adverse events and complications associated with training or leading to a withdrawal from the training were also carefully documented. The following parameters from the cardiopulmonary stress tests were analysed: peak workload, peak oxygen consumption (peak-VO2), metabolic equivalents (METs), respiratory exchange ratio (RER) at peak-VO2, minute ventilation-carbon dioxide production relationship (VE/VCO2 slope). The pharmacological therapy with the dose of heart failure drugs was analysed. The most used ACE-inhibitors (such as ramipril, lisinopril), b-blocker (bisoprolol) and diuretics (furosemide, spironolactone) were considered. Blood serum concentration of N-terminal pro-brain natriuretic peptide (NT-proBNP), evaluated using an immunological test, and the glomerular filtration rate (GFR), calculated using the modification of diet in renal disease (MDRD) formula, were included in the analysis. In order to assess statistical significance of the improvement observed during rehabilitation (end vs beginning of the stay) the student’s t-test and the Wilcoxon signed-rank test for paired differences were used, the latter test when the variables were not normally distributed. Normality was tested using the Shapiro–Wilk test. A level of significance p < 0.05 was considered as statistically significant. Statistical analysis was performed using SPSS 17.0 (IBM, Armonk, New York, USA).
Results Demographics From 1 February 2010–1 March 2012, 64 patients had a ventricular assist device implanted. Five patients died in hospital and four were transplanted before being transferred to the rehabilitation clinic and they were therefore excluded from the analysis. One patient was excluded because he started rehabilitation but had quit and rehospitalised after 13 days due to an extensive pleural effusion. Three patients (one adult and two children) performed the cardiac rehabilitation in another centre. One Bi-VAD patient was also excluded by the analysis. Three patients were not included in the study because of the unavailability of the rehabilitation records at the time of data collection. Finally, six patients were excluded since their rehabilitation stay occurred later than 1 April 2012. The remaining 41 patients underwent
Downloaded from cpr.sagepub.com at UNIV OF LETHBRIDGE on October 16, 2015
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32 6 days of rehabilitation 48 38 days after LVAD implantation. Nine patients received a Heart Mate II (HMII) (Thoratec Inc., Pleasanton, California, USA) device and 32 patients an HeartWare ventricular assist device (HVAD) device (HeartWare Inc., Miami Lakes, Florida, USA). Detailed demographics are given in Table 2. The average pump speed at admission in the rehabilitation centre was HVAD 2761 141 rpm and HMII 9421 440 rpm. Only small speed changes in three patients during the stay with an HVAD implanted
Diagnostic tests
Table 2. Patient demographics. Mean SD
Min, max
Age (y)
54.8 11.56
20, 75
Weight (kg)
80.0 14.6
47.4, 119.7
Height (m)
1.77 0.08
1.62, 1.96
Body mass index (kg/m2)
25.7 4.3
14.8, 34.4
n (%) Patients
41 (100)
Gender
Male Female
33 (80) 8 (20)
Pump type
HVAD
32 (78)
Thoratec HMII
9 (22)
POD at rehabilitation admission (days)
48 38
19, 188
Duration of rehabilitation (days)
32 6
22, 43
Aetiology
Ischaemic Idiopathic Other
were performed (180 rpm, 40 rpm and þ 20 rpm). In 34 patients the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) classification for pre-operative status was employed: level I 22%, level II 17%, level III 17%, and level IV–VII 27%. The first seven patients (17%) were not classified since the INTERMACS classification was not used at the time of implantation. An implantable cardioverter defibrillator, combined with cardiac resynchronization therapy (ICD/ CRT) device was implanted in 29 patients (71%).
19 (43) 17 (41) 5 (16)
HVAD: HeartWare ventrcular assist device; HMII: Heart Mate II; POD: post-operative day; SD: standard deviation.
Initial echocardiography did not show any signs of pericardial effusion or intracardiac thrombus formation, which would have been a contraindication for the exercise training. Twelve patients (29%) presented with atrial fibrillation and the remaining had normal sinus rhythm at the initial ECG examination. No patients presented with severe tachycardia or bradycardia. In 35 out of the 41 patients at least one cardiopulmonary stress test could be performed (Table 3). In the remaining six patients the cardiopulmonary stress test was not possible because of very poor general condition, orthopaedic limitations or inability to sit on the bicycle. The peak workload reached was 51 22 W, the peak-VO2 was 12.8 4.35 ml/min/kg (45 % of the ageand gender-matched reference value), corresponding to 3.7 1.2 METs. In 15 patients two tests could be performed: one at the beginning and one at the end of the rehabilitation stay. In this subgroup an improvement in the spiroergometry parameters could be observed (Table 3). The VE/VCO2 slope was measured until the respiratory compensation point, which was reached by 18 out of the 35 patients undergoing one single
Table 3. Spiroergometry data for all patients and for a subgroup that underwent two examinations (at the beginning and at the end of the rehabilitation stay). Data are reported as mean standard deviation. Patient subgroup (n ¼ 15)
Examination day (PrAD) Peak workload (W) Peak workload per kg (W/kg) Peak-VO2 (ml/min) Peak-VO2 per kg (ml/min/kg) % Reference value Metabolic equivalents RER at peak-VO2 VE/VCO2 slope
All patients (n ¼ 35)
Beginning
End
p-value
22.5 7.8 51.0 22.5 0.63 0.25 1031 393 12.81 4.35 45 15 3.7 1.2 1.07 0.12 34.0 7.3
6.7 2.6 44.4 17.6 0.60 0.26 790 510 11.32 4.12 40 14 3.3 1.2 1.09 0.13 37.8 7.9
27.3 5.7 61.5 24.6 0.79 0.28 1144 496 14.51 5.20 51 18 4.2 1.5 1.13 0.15 33.7 5.8
(CPR)
[1–7] [PREPRINTER stage]
EURO PEAN SO CIETY O F CARDIOLOGY ®
Original scientific paper
Safety and efficacy of cardiac rehabilitation for patients with continuous flow left ventricular assist devices
European Journal of Preventive Cardiology 0(00) 1–7 ! The European Society of Cardiology 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/2047487314558772 ejpc.sagepub.com
Christiane Marko1, Georg Danzinger2,3, Michael Ka¨ferba¨ck2,3, Thomas Lackner1, Rudolf Mu¨ller4, Daniel Zimpfer3,5, Heinrich Schima2,3,5 and Francesco Moscato2,3
Abstract Background: Despite the increasing use of left ventricular assist devices (LVADs) in terminal heart failure, cardiac rehabilitation protocols have not yet been documented in larger LVAD patient cohorts. The aim of this study was to investigate safety and efficacy of exercise training during a rehabilitation programme after post-operative discharge of LVAD patients. Methods: Rehabilitation data obtained between 2010–2012 from 41 LVAD patients (mean age 54.8 11.6 years; 20% female) were retrospectively analysed. The exercise protocol consisted of strength exercises for lower limbs, bicycle ergometry, walking and gymnastics. The numbers of training sessions, their duration and intensity as well as adverse events were documented. Spiroergometry was performed at least once and twice in a subgroup of 15 patients (at the beginning and end of rehabilitation). Results: Rehabilitation started 48 38 days post LVAD implantation with an average duration of 32 6 days. An increase in exercise capacity was observed. Duration (19 4 vs 14 2 min, p < 0.001) and intensity of bicycle ergometry increased (module number 6.2 2.8 vs 2.0 1.9, p < 0.001) as well as muscular strength all muscle groups trained (e.g. 33.6 15.2 vs 26.6 11.9 kg at the leg press, p ¼ 0.002). Spiroergometry revealed an increase of maximal oxygen consumption (14.5 5.2 vs 11.3 4.1 ml/min/kg, p ¼ 0.007) in the subgroup that underwent two examinations. In the whole population the average increase was lower (12.81 4.35 ml/min/kg). One training-related adverse event (nonsustained ventricular tachycardia) was observed. Conclusion: Exercise training for LVAD patient as part of a multidisciplinary rehabilitation programme is effective and safe. This warrants the broad application of exercise training after LVAD implantation.
Keywords Continuous flow left ventricular assist devices, cardiac rehabilitation, exercise capacity, exercise training Received 22 July 2014; accepted 16 October 2014
Introduction
1
Rehabilitation Center Felbring, Austria Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria 3 Ludwig Boltzmann Cluster for Cardiovascular Research, Austria 4 Pensionsversicherungsanstalt, Austria 5 Department of Cardiac Surgery, Medical University of Vienna, Austria 2
The implantation of continuous-flow left ventricular assist devices (LVADs) has become an established treatment for patients with end-stage heart failure.1,2 Current guidelines recommend LVAD implantation in selected end-stage heart failure patients both as a bridge to heart transplant (Class I, Level B) and as permanent implant (Class IIa, Level B).3 LVAD therapy allows an enhanced mobility in patient daily life in an increasing
Corresponding author: Christiane Marko, Rehabilitationszentrum Felbring der Pensionsversicherungsanstalt, Felbring 71, 2723 Muthmannsdorf, Austria. Email: [email protected]
Downloaded from cpr.sagepub.com at UNIV OF LETHBRIDGE on October 16, 2015
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[1–7] [PREPRINTER stage]
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European Journal of Preventive Cardiology 0(00)
number of patients and over longer periods of implant duration; exercise therapy thus contributes to an overall improvement in quality of life. However the numerous studies investigating cardiac rehabilitation and its benefit after heart transplantation,4 have not yet, in large patient cohorts, been extended to LVAD patients. To the authors’ knowledge there are very few reports5–10 about the safety and effectiveness of cardiac rehabilitation in LVAD patients. In particular, cardiac rehabilitation has not been evaluated when performed on a routine clinical basis involving all patients receiving an LVAD, including even the more critical ones. The present study seems therefore to be the first that assesses a stationary and structured cardiac rehabilitation programme involving exercise training of LVAD patients early after hospital discharge. The rehabilitation programme assessed here was aimed, first, to achieve patient independence and mobility in daily life and confidence in handling the assist device peripherals and then, to provide an overall improvement in the physical conditioning and therefore quality of life. Due to the complex interaction between a continuousflow LVAD and the patient haemodynamics, questions related to safety and efficacy of cardiac rehabilitation, especially in more critical patients, were expected and did arise.
Materials and methods Patient data from consecutive patients who had a ventricular assist device implanted at the General Hospital in Vienna from 1 February 2010–1 March 2012, were considered. Patients were included in the analysis if they underwent at least 21 consecutive days of rehabilitation from 1 March 2010–1 April 2012. Paediatric patients or those with a biventricular assist device (BiVAD) were excluded from the analysis. Since in Austria cardiac rehabilitation is funded by the government, nobody was excluded because of financial issues. Data collection and analysis were approved by the Institutional Review Board of Lower Austria.
Diagnostic tests Baseline examinations at the time of admission to the rehabilitation centre included echocardiography and electrocardiography (ECG) in all patients and, in patients rated stable enough, a cardiopulmonary stress test. At the end of rehabilitation a cardiopulmonary stress test was again performed in those patients rated stable enough. The loading protocol for the cardiopulmonary stress test was adapted to the estimated workload of the patient and a duration of the test was varied from 8–12 min.
Rehabilitation programme and the medical training therapy If patients were haemodynamically stable, which meant that during early mobilisation no clinical signs of orthostatic dysregulation, hypovolaemia, infections as well as no low-flow and suction alarms were observed, the medical training therapy could be initiated. It consisted of strength as well as endurance training together with walking and gymnastics, according to the exercise recommendation for patients suffering from heart failure.11 To determine the intensity of the training sessions the perceived level of exertion according to the Borg scale12 was used. An exertion of somewhat hard intensity (grade 13 in the Borg scale) was aimed for. This intensity corresponds to training between the anaerobic threshold and the respiratory compensation point.13 Usual methods for continuously monitoring the intensity of training could not be used, e.g. arterial blood pressure was not measurable using an automatic oscillometric system because of the low arterial pressure pulsatility characteristic of patients with continuous flow LVADs.14 The measurement of arterial blood pressure was only performed before and after the training sessions. The patient did not start the exercise training if a blood pressure higher than 90 mm Hg15 was observed. Strength training was directed to muscle groups of the lower extremities (leg press, leg extensor, leg flexor, lower limb abductor, lower limb adductor) with two series of 12 repetitions each. Special care was taken to avoid forced respiration during exercise. Aerobic training consisted of bicycle ergometry, using an interval training schema that included continuous ECG monitoring. Interval training has been employed previously for patients with chronic heart failure16 and consists of alternating periods of high and low intensity in order to increase time spent at a high effort and to stimulate cardiovascular and muscular adaptation more strongly. Twelve modules of increasing intensity (coded B1–B12, see Table 1) were standardised. The training protocol included 3 min bicycling with no load at the beginning and at the end of the session to warm up and cool down. Walking training was performed in groups of patients having approximately the same physical capabilities. There were five different groups that walked along paths covering different distances and elevations in different amounts of time (W1–W5, see also Table 1). Gymnastic training was organised in groups as well as in individual sessions. Five different groups performed different kinds of exercises (coordination, strength and balance training) in different intensity grades and body positions (G1–G5 as described in Table 1). Patients were assigned to their groups
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XML Template (2014) [6.11.2014–1:31pm] //blrnas3.glyph.com/cenpro/ApplicationFiles/Journals/SAGE/3B2/CPRJ/Vol00000/140155/APPFile/SG-CPRJ140155.3d
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Table 1. Rehabilitation training schema.
Acquired data and statistical analysis
Load phase (W)
Recovery/load phase duration (s)
Bicycle ergometry training B1 1 B2 1 B3 1 B4 5 B5 5 B6 5 B7 5 B8 10 B9 10 B10 10 B11 10 B12 10
5 15 20 25 25 30 40 50 60 70 90 120
60/30 60/20 60/30 60/20 60/30 60/20 60/20 60/20 60/20 60/20 60/20 60/20
Group
Distance (km)
Elevation (m)
Module
Recovery phase (W)
Duration (min)
Walking training W1 30 W2 30 W3 45 W4 60 W5 90
0.6 1.0 1.6–2.0 2.2–2.8 4.5–5.5
0 0 30 60 130
Group
Body position
Gymnastic G1 G2 G3 G4 G5
training Sitting on a chair with a seatback Sitting on a chair with no seatback Standing and sitting Lying, standing and sitting Any body position
according to the underlying cardiac illness, age and, as needed, specific orthopaedic problems and/or postoperative limitations. For this class of training, the aim was to change to a better-performing group. Individual gymnastics were aimed at training coordination, balance and strength, especially of respiratory muscles, depending on the individual patient needs. Throughout the rehabilitation period, patients were closely followed to detect early signs of decompensation or hypovolaemia. Our pharmacological treatment was aimed at increasing the dosage of angiotensin converting enzyme (ACE) inhibitor and/or b-blocker medication in very low steps although the patients were stable as it is recommended for heart failure and also for LVAD patients.3,15 Criteria for interrupting the training were pain (especially localised in the thorax), ventricular arrhythmias, haemodynamic instability (pump low-flow alarm, suction alarm, dizziness), subjective exhaustion and neurologic symptoms.
The number of training sessions performed by each patient was documented during through the whole rehabilitation period. In particular, changes in lifted weight for strength training, changes in training intensity and duration for the bicycle ergometry, and training and changes of group in walking and gymnastic training were recorded. Adverse events and complications associated with training or leading to a withdrawal from the training were also carefully documented. The following parameters from the cardiopulmonary stress tests were analysed: peak workload, peak oxygen consumption (peak-VO2), metabolic equivalents (METs), respiratory exchange ratio (RER) at peak-VO2, minute ventilation-carbon dioxide production relationship (VE/VCO2 slope). The pharmacological therapy with the dose of heart failure drugs was analysed. The most used ACE-inhibitors (such as ramipril, lisinopril), b-blocker (bisoprolol) and diuretics (furosemide, spironolactone) were considered. Blood serum concentration of N-terminal pro-brain natriuretic peptide (NT-proBNP), evaluated using an immunological test, and the glomerular filtration rate (GFR), calculated using the modification of diet in renal disease (MDRD) formula, were included in the analysis. In order to assess statistical significance of the improvement observed during rehabilitation (end vs beginning of the stay) the student’s t-test and the Wilcoxon signed-rank test for paired differences were used, the latter test when the variables were not normally distributed. Normality was tested using the Shapiro–Wilk test. A level of significance p < 0.05 was considered as statistically significant. Statistical analysis was performed using SPSS 17.0 (IBM, Armonk, New York, USA).
Results Demographics From 1 February 2010–1 March 2012, 64 patients had a ventricular assist device implanted. Five patients died in hospital and four were transplanted before being transferred to the rehabilitation clinic and they were therefore excluded from the analysis. One patient was excluded because he started rehabilitation but had quit and rehospitalised after 13 days due to an extensive pleural effusion. Three patients (one adult and two children) performed the cardiac rehabilitation in another centre. One Bi-VAD patient was also excluded by the analysis. Three patients were not included in the study because of the unavailability of the rehabilitation records at the time of data collection. Finally, six patients were excluded since their rehabilitation stay occurred later than 1 April 2012. The remaining 41 patients underwent
Downloaded from cpr.sagepub.com at UNIV OF LETHBRIDGE on October 16, 2015
XML Template (2014) [6.11.2014–1:31pm] //blrnas3.glyph.com/cenpro/ApplicationFiles/Journals/SAGE/3B2/CPRJ/Vol00000/140155/APPFile/SG-CPRJ140155.3d
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32 6 days of rehabilitation 48 38 days after LVAD implantation. Nine patients received a Heart Mate II (HMII) (Thoratec Inc., Pleasanton, California, USA) device and 32 patients an HeartWare ventricular assist device (HVAD) device (HeartWare Inc., Miami Lakes, Florida, USA). Detailed demographics are given in Table 2. The average pump speed at admission in the rehabilitation centre was HVAD 2761 141 rpm and HMII 9421 440 rpm. Only small speed changes in three patients during the stay with an HVAD implanted
Diagnostic tests
Table 2. Patient demographics. Mean SD
Min, max
Age (y)
54.8 11.56
20, 75
Weight (kg)
80.0 14.6
47.4, 119.7
Height (m)
1.77 0.08
1.62, 1.96
Body mass index (kg/m2)
25.7 4.3
14.8, 34.4
n (%) Patients
41 (100)
Gender
Male Female
33 (80) 8 (20)
Pump type
HVAD
32 (78)
Thoratec HMII
9 (22)
POD at rehabilitation admission (days)
48 38
19, 188
Duration of rehabilitation (days)
32 6
22, 43
Aetiology
Ischaemic Idiopathic Other
were performed (180 rpm, 40 rpm and þ 20 rpm). In 34 patients the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) classification for pre-operative status was employed: level I 22%, level II 17%, level III 17%, and level IV–VII 27%. The first seven patients (17%) were not classified since the INTERMACS classification was not used at the time of implantation. An implantable cardioverter defibrillator, combined with cardiac resynchronization therapy (ICD/ CRT) device was implanted in 29 patients (71%).
19 (43) 17 (41) 5 (16)
HVAD: HeartWare ventrcular assist device; HMII: Heart Mate II; POD: post-operative day; SD: standard deviation.
Initial echocardiography did not show any signs of pericardial effusion or intracardiac thrombus formation, which would have been a contraindication for the exercise training. Twelve patients (29%) presented with atrial fibrillation and the remaining had normal sinus rhythm at the initial ECG examination. No patients presented with severe tachycardia or bradycardia. In 35 out of the 41 patients at least one cardiopulmonary stress test could be performed (Table 3). In the remaining six patients the cardiopulmonary stress test was not possible because of very poor general condition, orthopaedic limitations or inability to sit on the bicycle. The peak workload reached was 51 22 W, the peak-VO2 was 12.8 4.35 ml/min/kg (45 % of the ageand gender-matched reference value), corresponding to 3.7 1.2 METs. In 15 patients two tests could be performed: one at the beginning and one at the end of the rehabilitation stay. In this subgroup an improvement in the spiroergometry parameters could be observed (Table 3). The VE/VCO2 slope was measured until the respiratory compensation point, which was reached by 18 out of the 35 patients undergoing one single
Table 3. Spiroergometry data for all patients and for a subgroup that underwent two examinations (at the beginning and at the end of the rehabilitation stay). Data are reported as mean standard deviation. Patient subgroup (n ¼ 15)
Examination day (PrAD) Peak workload (W) Peak workload per kg (W/kg) Peak-VO2 (ml/min) Peak-VO2 per kg (ml/min/kg) % Reference value Metabolic equivalents RER at peak-VO2 VE/VCO2 slope
All patients (n ¼ 35)
Beginning
End
p-value
22.5 7.8 51.0 22.5 0.63 0.25 1031 393 12.81 4.35 45 15 3.7 1.2 1.07 0.12 34.0 7.3
6.7 2.6 44.4 17.6 0.60 0.26 790 510 11.32 4.12 40 14 3.3 1.2 1.09 0.13 37.8 7.9
27.3 5.7 61.5 24.6 0.79 0.28 1144 496 14.51 5.20 51 18 4.2 1.5 1.13 0.15 33.7 5.8
