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Abstract
Background—Doppler ultrasound is the clinical gold standard for noninvasive blood pressure (BP) measurement among continuous-flow left ventricular assist device patients. The relationship of Doppler BP to systolic BP (SBP) and mean arterial pressure (MAP) is uncertain and Doppler measurements require a clinic visit. We studied the relationship between Doppler BP and both arterial-line (A-line) SBP and MAP. Validity and reliability of the Terumo Elemano BP Monitor, a novel slow cuff-deflation device that could potentially be used by patients at home, were assessed.
Methods and Results—Doppler and Terumo BP measurements were made in triplicate among 60 axial continuous-flow left ventricular assist device (HeartMate II) patients (30 inpatients and 30 outpatients) at 2 separate exams (360 possible measurements). A-line measures were also obtained among inpatients. Mean absolute differences (MADs) and correlations were used to determine within-device reliability (comparison of second and third BP measures) and between-device validity. Bland–Altman plots assessed BP agreement between A-line, Doppler BP, and Terumo Elemano. Success rates for Doppler and Terumo Elemano were 100% and 91%. Terumo Elemano MAD for repeat SBP and MAP were 4.6±0.6 and 4.2±0.6 mm Hg; repeat Doppler BP MAD was 2.9±0.2 mm Hg. Mean Doppler BP was lower than A-line SBP by 4.1 (MAD=6.4±1.4) mm Hg and higher than MAP by 9.5 (MAD=11.0±1.2) mm Hg; Terumo Elemano underestimated A-line SBP by 0.3 (MAD=5.6±0.9) mm Hg and MAP by 1.7 (MAD=6.0±1.0) mm Hg.
Conclusions—Doppler BP more closely approximates SBP than MAP. Terumo Elemano was successful, reliable, and valid when compared with A-line and Doppler.
Introduction
Continuous-flow (CF) left ventricular assist devices (LVADs) have become the standard of care in patients with end-stage heart failure as bridge to transplantation and destination therapy. They offer several advantages compared with the older version pulsatile devices, such as smaller size, enhanced durability, and better long-term outcomes.1,2
Editorial see p 879
Clinical Perspective on p 1012
Accurate monitoring of arterial blood pressure (BP) is required for optimization of early postoperative and of long-term care in CF-LVAD patients. An arterial line (A-line) is routinely used to measure BP during the initial postoperative period. Once the A-line is removed, BP can be obtained noninvasively using automated BP monitors or Doppler ultrasound. Automated BP monitors are accurate, but their success rate is low (≈50%),3 due to reduced pulse pressure (PP) in CF-LVAD patients. Consequently, Doppler ultrasound is commonly used to assess BP in patients with CF-LVAD during clinical visits. Current clinical understanding is that Doppler BP represents mean arterial pressure (MAP) rather than systolic BP (SBP); however this remains controversial.3 Although Doppler assessments have excellent success rates (≈95%) and high validity,3 these measurements are time-consuming and cannot be performed by patients at home, requiring highly trained personal in the hospital setting.
In an attempt to overcome the shortcomings of current noninvasive methods for BP measurement in CF-LVAD patients, we tested the success rate, reliability, and validity of a novel slow cuff-deflation system, which enhances sensitivity for detection of BP in patients with reduced arterial PP. The Terumo Elemano BP Monitor was compared with BP measurements taken with either A-line (gold standard) or Doppler ultrasound (clinical standard). We also compared the performance of an automated BP monitor (GE CARESCAPE V100) with A-line and Doppler, as this automated device is routinely used at our Institution, in patients on CF-LVAD support.
Methods
Patient Population
A total of 60 patients were prospectively studied at 2 time points as follows: (1) 30 inpatients were assessed immediately following implantation of an axial flow CF-LVAD, the Heart Mate II (Thoratec Corporation, CA; inpatient visit v1), and the second encounter (inpatient v2) occurred a minimum of 3 days later after the patient was no longer in the intensive care unit and no longer had an A-line; and (2) a separate group of 30 outpatients on Heart Mate II LVAD support, who presented to clinic for routine follow-up, were assessed at 2 separate visits (outpatient v1 and outpatient v2, respectively). Patients enrolled in the inpatient group could not be enrolled in the outpatient group.
The study protocol was approved by the local institutional review board and all subjects signed provided informed consent.
Study Protocol
During their first encounter (inpatient v1), LVAD inpatients had BP measurements by a radial A-line obtained immediately prior to each of the 3 noninvasive modalities tested (see below). Before measurements were recorded, the A-line was flushed once and leveled to the pressure transducer (IntelliVue, Phillips, the Netherlands). BP measurements were done in triplicate for each method. A-line BP was recorded in a paired fashion, prior to each of the triplicate measurements by each noninvasive modality. All BP measurements were obtained in the same arm as the A-line.
For all patients, 3 separate BPs were taken4 with each of the following 3 different noninvasive BP measurement methods: Doppler ultrasound (Lumeon Doppler System, Houston, TX), GE CARESCAPE V100 (Fairfield, CT) automated BP monitor, and Terumo Elemano BP (Somerset, NJ) monitor.
Doppler ultrasound BP measurements were obtained using a calibrated sphygmomanometer as previously described.4 Briefly, the Doppler probe was placed over the brachial artery while the examiner verified that the brachial pulse could be auscultated. The cuff was placed proximal to the Doppler probe, attached to a manometer, and inflated until the pulse was no longer audible by Doppler. The cuff was then slowly deflated (2–3 mm Hg/s) allowing the reestablishment of blood flow and a reading was taken when the pulse became audible again. The Terumo Elemano BP monitor uses a double-cuff oscillometric, slow-deflation technology. BP measures were taken according to manufacturer defaults.5 The GE CARESCAPE V100 monitor was chosen for its routine use at our hospital, to be taken as representative of a standard automated BP monitor. Appropriately sized BP cuffs were chosen for all noninvasive modalities, as previously described.4
BP measurements were taken in the upper arm in triplicate, and the average of the last 2 measurements was used for subsequent analyses.4 Because the Terumo Elemano provides only the SBP, diastolic BP, and heart rate (HR), MAP was calculated as follows: (SBP+2×diastolic BP)/3. The GE CARESCAPE V100 monitor provides a MAP automatically. Whenever possible, the same settings were used during the first and second encounter: the patient was seated, with legs uncrossed, and the back and arm supported, such that the middle of the cuff on the upper arm is at the level of the right atrium (the midpoint of the sternum). In the CTICU, the patient was permitted to be supine. All noninvasive measurements were taken in the same arm as the A-line.
BP measures were performed in the following order: Doppler ultrasound, GE CARESCAPE V100, and Terumo Elemano. The second encounter (inpatient v2) occurred a minimum of 3 days later and when the patient was no longer in the intensive care unit and no longer had an A-line. The BP measurements for outpatients were performed on 2 separate follow-up visits (outpatient v1 and outpatient v2), and with the same methodology and sequence described above, except that no A-line measurement was available. Ability to provide a reading on any BP measurement attempt was defined as success.
At the time of each encounter, HR and Heart Mate II LVAD data including LVAD speed and pulsatility index were recorded. In inpatients, HR regularity, that is, regular versus irregular, was also assessed, based on ECG and telemetry monitoring. Of note, patients in atrial fibrillation but with regular ventricular pacing were labeled as regular; atrial fibrillation with an irregular ventricular rate and sinus rhythm with frequent premature atrial or ventricular complexes were labeled as irregular.
Two inpatients had their A-line data recorded at the beginning of the first visit, that is, prior to Doppler, but not prior to subsequent BP measurements using the other modalities; in these 2 patients these initial (and only) A-line readings were used for all comparisons. Additionally, 2 inpatients did not have a second set of BP measurements during a second visit (v2) prior to hospital discharge because of logistical reasons.
Statistical Analysis
All analyses were performed in SAS version 9.3. Descriptive data are presented as proportions or means±SD (unless otherwise specified). Reliability and validity were assessed using multiple approaches. For reliability, mean absolute differences (MAD) were computed between the second and third repeat measures within each device. When MADs are presented for the overall patient sample—which includes repeat BP measurements for each patient at 2 time points—a no-intercept random-effects mixed regression model with patient modeled as a random effect was used to generate SEs accounting for the correlated nature of the data. The default correlation structure for these models is variance components. Intraclass correlation coefficients were also calculated using all 3 BP measures among subgroups defined by patient (inpatient or outpatient) and time (v1 or v2). To assess validity, MADs were calculated comparing BP values derived from Doppler, Terumo Elemano, and GE CARESCAPE V100 versus A-line among n=30 inpatients. Bland–Altman plots were constructed for various comparisons of agreement between Terumo Elemano, Doppler, and A-line systolic BP measurements. Because 2 within-patient measures were averaged to compute mean BP values, a corrected SD was computed as previously described.6 Similarly, among outpatients, MADs were calculated comparing BP values derived from Terumo Elemano and GE CARESCAPE V100 versus Doppler, and a Bland–Altman plot was constructed comparing Terumo Elemano and Doppler BP. Mean between-device differences for Bland–Altman plots are presented (as compared with MAD) because this provides information on whether or not comparison measurements over- or underestimate gold standard measures. Therefore, we present both MADs and mean differences for between-device comparisons as both measures provide unique and important information. As a secondary analysis, we also present standard Pearson correlation coefficients as a crude metric of both within- and between-device agreement because they are commonly understood statistics in the medical literature; however, the reader should be cautioned that they are not ideal for studies of reliability and validity6 as Pearson correlation coefficients estimate degree of linear association between variables and not necessarily degree of similarity.
When assessing associations between clinical parameters and device measurement success, we used generalized linear models (PROC GENMOD) in SAS with a logit link to generate odds ratios summarizing these associations. This method allowed us to the multiple within-patient measurements taken (as opposed to 1 measure per patient) and properly account for the correlation of outcomes within patient. Finally, ANOVA was used to compare mean PP among patients with 3 successful BP readings versus <3 successful BP readings.
Results
Patient Characteristics
Baseline characteristics of patients are listed in Table 1. Overall, the average age of patients was 60 years, 57% had heart failure of ischemic etiology, 70% had a Heart Mate II LVAD implanted as a bridge to transplantation. The first inpatient visit (v1) occurred, on average, 4±2 (range, 1–9) days, postoperatively and the second visit (v2) occurred an average of 13±5 (range, 2–24) days after the first encounter. Outpatient visits (v1 and v2) were separated by an average of 49±30 (range, 8–135) days. One notable difference between inpatients and outpatients was the HR, which was higher among inpatients. Irregularity of HR was noted in 21% of inpatients.
Characteristics of Patients With Continuous-Flow Left Ventricular Assist Device
Measurement Success
Among 60 patients (58 of which had both per-protocol encounters) the total number of BP measurement attempts made for Doppler, Terumo Elemano, and GE CARESCAPE V100 were 354. The overall success rate for Doppler was 100%. For Terumo Elemano and GE CARESCAPE V100, the success rates were 91% and 63%, respectively (Table 2).
Blood Pressure Measurement Success Rates [95% Confidence Intervals] by Device Among Patients With Continuous-Flow Left Ventricular Assist Device
A-line PP (range, 3–41 mm Hg; median, 20 mm Hg) and HR regularity were associated with Terumo Elemano and GE CARESCAPE V100 measurement success. Among inpatients with A-line measurements, a 9 mm Hg (equivalent to 1 SD) increase in PP was associated with an ≈100% increase in the odds of Terumo Elemano success (P=0.06) and an ≈300% increase in the odds of GE CARESCAPE V100 success (P<0.001); respective odds ratios [95% confidence interval] for Terumo Elemano and GE CARESCAPE V100 success are 1.99 [0.98, 2.06] and 3.93 [1.90, 7.81]. The mean A-line PP with <3 successful Terumo Elemano readings versus those with 3 successful Terumo Elemano readings was 15 versus 22 mm Hg (P=0.06). Similarly, mean A-line PP was 15 versus 23 mm Hg (P=0.009) among patients with <3 versus 3 successful GE CARESCAPE V100 readings (P=0.33).
Cardiac rhythm was also associated with measurement success. A regular HR was strongly associated with an increase in the odds of GE CARESCAPE V100 success; 7.0 [2.3, 21.5], P<0.001. However, results were substantially weaker and nonstatistically significant for associations between regular cardiac rhythm and Terumo Elemano success: 2.1 [0.5, 9.3], P=0.33.
Reliability of Repeat Within-Device Measures
All devices demonstrated good reliability. The overall correlation between the second and third SBP measures for A-line, Doppler, Terumo Elemano, and GE CARESCAPE V100 were: 0.99 (P<0.0001), 0.95 (P<0.0001), 0.82 (P<0.0001), 0.93 (P<0.0001). For MAP, the overall correlation between the second and third measures for A-line, Terumo Elemano, and GE CARESCAPE V100 were: 0.98 (P<0.0001), 0.87 (P<0.0001), 0.95 (P<0.0001). Table I in the online-only Data Supplement presents inter- and intraclass correlation coefficients for repeat measures according to device, clinical setting, and time point. Overall, the respective MADs±SE between second and third SBP measures for A-line, Doppler, Terumo Elemano, and GE CARESCAPE V100 were: 1.6±0.3, 2.9±0.2, 4.6±0.6, and 3.7±0.5 mm Hg. For MAP, the respective MADs±SE between second and third measures for A-line, Terumo Elemano, and GE CARESCAPE V100 were: 1.2±0.4, 4.2±0.7, and 2.7±0.3 mm Hg. Within-device MAD values for SBP, diastolic BP, and MAP across all methods, clinical setting, and patient visit are presented in Table II in the online-only Data Supplement.
Validity of Doppler, Terumo Elemano, and GE CARESCAPE Versus A-line (Gold Standard)
Doppler, Terumo Elemano, and GE CARESCAPE V100 SBP measurements demonstrated strong correlations (ranging from 0.73 to 0.88; all P<0.0001) with gold standard A-line SBP measurements (Table 3). Overall, the respective MADs±SE between A-line SBP and either Doppler BP, Terumo Elemano, or GE CARESCAPE V100 SBP were: 6.4±1.4, 5.6±0.9, and 5.2±0.7 mm Hg. While successful in fewer patients, GE CARESCAPE V100 often performed as well as Doppler and Terumo Elemano, and in some instances marginally better, depending on the clinical setting (Table 3). As shown in Table 3, restricting the analysis to a fixed sample of patients on which all devices yielded a measurement (n=17) had minimal influence on which device performed best.
Between-Device Mean Absolute Differences (SE) and Correlations Among Patients With Continuous-Flow Left Ventricular Assist Device
Among both inpatients and outpatients, Doppler BP tended to more closely reflect SBP rather than MAP by A-line, Terumo Elemano, or GE CARESCAPE V100 (Figure 1). For example, among inpatients, the mean differences (as opposed to MAD) between Doppler BP and A-line BP showed that Doppler BP was lower than SBP by 4.1 mm Hg, while Doppler BP was higher than MAP by 9.5 mm Hg. However, although Doppler BP consistently reflects SBP, in situations of low PP Doppler BP may also closely approximate MAP. For example, the mean difference between Doppler BP and A-line SBP was consistent among patients with A-line PP below the median (20 mm Hg) versus above the median: −5.5 versus −3.2 mm Hg, respectively (P=0.46). In contrast, the mean difference between Doppler BP and A-line MAP was markedly different among patients with A-line PP below the median versus above the median: 3.0 versus 13.6 mm Hg, respectively (P<0.01). Similarly, Figure 2 shows that increased A-line PP is also related to a greater difference between Doppler BP and Terumo Elemano MAP. Nevertheless, despite a strong correlation, there remains a sizeable number of patients who have a difference between Doppler BP and Terumo Elemano MAP of >5 mm Hg even when PP is low. This observation reinforces the importance of using Terumo Elemano rather than Doppler to assess MAP in CF-LVAD patients.
Mean blood pressure values (±SE) among: (A) inpatients according to measurement device among 23 inpatients (results for GE CARESCAPE V100 include n=17 patients with successful measures); and (B) outpatients according to measurement device among 27 outpatients (results for GE CARESCAPE V100 include n=12 patients with successful measures). DBP indicates diastolic blood pressure; MAP, mean arterial pressure; and SBP, systolic blood pressure.
Scatterplot of the difference between Doppler blood pressure and Terumo mean arterial pressure plotted against arterial-line pulse pressure.
Bland–Altman plots demonstrate that agreement between Terumo Elemano and A-line (SBP or MAP) did not vary according to BP level. Ninety-five percent of Terumo Elemano SBP measurements were within 15 mm Hg of A-line SBP (Figure 3A) and 95% of Terumo Elemano MAP measurements were within 16 mm Hg of A-line MAP (Figure 3B). The Bland–Altman plot was similar for Doppler versus A-line SBP (Figure 3C).
Bland–Altman plots comparing: (A) A-line systolic blood pressure to Terumo Elemano systolic blood pressure, mean difference=−0.34, corrected SD=7.9; (B) A-line mean arterial pressure to Terumo Elemano mean arterial pressure, mean difference=−1.7, corrected SD=8.3; (C) A-line systolic blood pressure to Doppler blood pressure, mean difference=−4.1, corrected SD=7.4. Mean blood pressure differences were calculated as Terumo Elemano minus A-line (Figure 2A and 2B) or Doppler minus A-line (Figure 2C).
Validity of Terumo Elemano and CARESCAPE V100 Versus Doppler (Clinical Standard)
Among all patients (at both visits) with successful second and third BP readings, the overall correlations between mean Doppler BP and mean SBP assessed using either Terumo Elemano or GE CARESCAPE V100 were 0.85 (P<0.0001; Figure 4A) and 0.81 (P<0.0001). The overall MADs between Doppler BP and mean SBP assessed using either Terumo Elemano or GE CARESCAPE V100 were 5.7±0.7 and 7.1±1.2 mm Hg. Table 3 shows the between-device MADs and correlation coefficients comparing Doppler BP with Terumo Elemano and GE CARESCAPE V100 SBP among patient subgroups according to clinical setting and time point. The Bland–Altman plot for Doppler versus Terumo Elemano SBP is shown in Figure 4B. Of note, pump speed was not associated with agreement between Doppler BP and Terumo Elemano SBP; for a 1000 point decrease in pump speed, there was <1 point, nonstatistically significant increase in the MAD between Doppler BP and Terumo Elemano SBP (P=0.53).
A, Scatterplot of mean Doppler systolic blood pressure versus mean Terumo Elemano systolic blood pressure among inpatients and outpatients at both visits 1 and 2; and (B) Bland–Altman plot comparing Doppler blood pressure to Terumo Elemano systolic blood pressure among inpatients and outpatients at visit 1; mean difference=−3.1, corrected SD=7.3. Only visit 1 results presented so that the appropriate corrected SD could be presented. Results from visit 2 were consistent with those from visit 1.
Discussion
This study is the largest published series to date analyzing invasive and noninvasive BP measurements in axial CF-LVADs, in both the inpatient and outpatient setting. The results indicate that (1) Doppler BP better reflects SBP rather than MAP; (2) Terumo Elemano BP monitor has a high rate of measurement success, particularly in comparison to traditional automated BP devices; and (3) Terumo Elemano provides an accurate and reliable measurement of SBP and MAP.
Throughout the past years axial and more recently centrifugal CF-LVADs have replaced pulsatile devices (as bridge to transplantation or destination therapy) due to better outcomes and fewer complications in end-stage heart failure patients. Regular and reliable assessment of arterial BP is important for optimization of cardiovascular care postoperatively and after discharge from the hospital. In the early postoperative period, an A-line is routinely used for BP monitoring. After the A-line is removed, noninvasive modalities of assessment are critical for adequate patient care. However, due to the reduced PP, which may fall below the sensitivity range of auscultatory and automated BP methods, it is often difficult or impossible to measure BP using standard techniques during CF-LVAD support. Consequently, current recommendations are to use Doppler ultrasound for arterial BP measurement in patients.7
Clinical recommendations are to maintain the MAP in the range of 70 to 80 mm Hg and not to exceed 90 mm Hg, as high afterload my compromise unloading of the left ventricle.7 Although there is general agreement on these recommendations, there is less consensus on how to accurately measure BP in patients on support with a CF-LVAD. Additionally, without having direct A-line measurements, it is unclear whether Doppler BP represents the SBP or MAP in the absence of a normal arterial waveform, although, based on limited published data,3 many care providers have considered the Doppler BP to reflect the MAP.
A Doppler ultrasound probe can detect flow at any point during the cardiac cycle and can measure a pressure in almost all CF-LVAD patients as demonstrated in our data and by others.3 Knowing whether Doppler more closely measures SBP or MAP is important for clinical decision making, but few studies provide data to address this issue. One group reported that in 17 patients who underwent HeartMate II implantation, the mean difference between Doppler and A-line MAP was 0.2±10.5 mm Hg compared with a mean difference between Doppler and A-line SBP of 8.6±9.5 mm Hg, thus suggesting that Doppler BP values more closely represent the true MAP as opposed to true SBP.3 Conversely, we found that Doppler BP underestimates SBP by 4.1±1.5 mm Hg and overestimates MAP by 9.5±1.9 mm Hg, thus suggesting that Doppler better reflects SBP. We further observed that the relationship between Doppler BP and SBP was not meaningfully affected by PP, while the relationship between Doppler BP and MAP was substantially influenced by PP. This is expected from a hemodynamic perspective because Doppler detects arterial blood flow, which will consistently occur as soon as the cuff pressure falls below the SBP. Therefore, lower PPs in the previous study might have narrowed the difference between SBP and MAP resulting in Doppler BP values that were closer to the MAP values. Other methodological differences in acquisition of Doppler BP, that is, slower versus faster rate of cuff release, may also explain the discrepancy between our study and others.3 This observation has important clinical consequences, as it suggests that titration of outpatient vasoactive medications to a Doppler BP of 70 to 80 mm Hg, as has been suggested previously, may produce adverse side effects of hypotension, such as dizziness or syncope, among patients with substantial pulsatililty where Doppler is a better reflection of SBP than MAP. From this perspective, our data suggest that Terumo Elemano BP Monitor offers a more useful tool to meet recommended MAP goals not only in the outpatient, but also in the inpatient setting when A-line measurements are no longer available. Other critical limitations of Doppler methodology are its time-consuming nature and requirement for trained personal in the hospital setting.
The Terumo Elemano BP Monitor has a slow-deflation setting, which is designed to improve the sensitivity of BP measurements in patients with a reduced PP. In this study, the Terumo Elemano BP Monitor was successful, reproducible, and valid when compared with A-line (gold standard) and Doppler (clinical standard). Specifically, we show that Terumo Elemano measures have less bias in estimating A-line SBP (Figure 3A; Terumo Elemano versus A-line) than Doppler (Figure 3C) and importantly that Terumo Elemano provides a reasonable estimate of MAP in LVAD patients. This portable BP device is relatively inexpensive (≈$200), weighs only120 g, and is powered by a single AA battery. While most centers currently use Doppler ultrasound for BP management, our results suggest that the Terumo Elemano BP monitor, when successful, provides an accurate and more applicable alternative. In addition, it also offers other advantages, which are typical of automated BP devices, such as the elimination of observer error and white coat effect, and the potential for more BP readings.
A standard automated BP monitor, the GE Dinamap CARESCAPE V100, was also tested in this study. Our results indicate that this method has a success rate of only 63% compared with 91% of Terumo Elemano, a result which is consistent with the literature on standard automated BP methodologies.3 Nevertheless, when obtainable, readings are accurate and can be used to direct patient care. However, the size (>2 kg) of this on-wheel device and its cost (>$2500) make the use of this automated BP monitor impractical, particularly in the outpatient setting.
Limitations of our study include the lack of blinding between the A-line recordings and the Doppler ultrasound recordings. This may have led to unintentional bias toward (or against) Doppler BP agreement. However, our Doppler correlation results seem consistent overall with previous publications.3 Also, that Terumo Elemano BP measurement is overall successful and valid does not mean that it will provide accurate readings in all patients. There were a substantial number of study subjects in whom the measurement difference compared with A-line (gold standard) or Doppler (current clinical standard) was >10 mm Hg. For this reason, we agree with the current American Heart Association recommendation that Terumo Elemano, as any oscillometric BP monitor, should be validated on each patient, that is, against A-line and Doppler postoperatively after LVAD implantation, before the readings are accepted as reliable and valid.4 One additional limitation is that our study did not include patients supported with centrifugal CF-LVADs.
The present study shows that (1) the Terumo Elemano BP monitor offers reliable measurement of BP in the majority of patients on axial CF-LVAD support; (2) it correlates closely with SBP and adequately with MAP by A-line; (3) the difference between SBP and MAP varies between patients, such that (4) the target for BP management remains to be established for patients with substantial pulsatility. Based on these conclusions, when the targets for BP have been identified for a given patient, the Terumo Elemano offers potential for valid and reliable long-term management using home BP monitoring.
Sources of Funding
This work was supported by Thoratec Corporation from an educational grant to Columbia University Medical Center.
Disclosures
Drs Jorde and Naka are consultants to Thoratec Corporation. The other authors report no conflict.
Footnotes
The online-only Data Supplement is available at http://circheartfailure.ahajournals.org/lookup/suppl/doi:10.1161/CIRCHEARTFAILURE.112.000186/-/DC1.
- Received November 20, 2012.
- Accepted June 20, 2013.
- © 2013 American Heart Association, Inc.
References
Clinical Perspective
This study prospectively analyzes invasive and noninvasive blood pressure (BP) measurements in patients on continuous-flow left ventricular assist device support. Due to the reduced pulse pressure, noninvasive BP measurements are challenging in continuous-flow left ventricular assist device patients; hence, Doppler ultrasound is frequently used. However, the relationship of Doppler BP to systolic BP and mean arterial pressure remains uncertain. In addition, Doppler BP measurement cannot be performed by patients at home, requiring trained personnel in the hospital setting. Our results indicate that (1) contrary to previous reports, Doppler BP better reflects systolic BP rather than mean arterial pressure; (2) Terumo Elemano (an automated BP device with a slow cuff-deflation setting to enhance sensitivity) has a high rate of measurement success, particularly in comparison to traditional automated BP devices; and (3) Terumo Elemano BP monitor provides an accurate and reliable measurement of systolic BP and of mean arterial pressure. The data from this study may allow physicians to more accurately optimize medical treatment both in the inpatient and outpatient setting. Further studies are warranted to test whether home BP monitoring may translate into fewer hypo- and hypertension-related events and, potentially, into a higher rate of myocardial recovery by enabling faster uptitration of neurohormonal blockade.
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