Laila Hübbert

Effects of long-term nocturnal oxygen treatment in patients with severe heart failure

Sleep-disordered breathing (SDB) is common in patients with heart failure (HF) and leads to disturbed sleep. The objective of this study was to determine the persistent effects of long-term nocturnal oxygen treatment in patients with severe HF regarding (1) objective outcomes, such as sleep, SDB, cardiac function, and functional capacity; (2) subjective outcomes, such as self-assessed sleep difficulties, daytime sleepiness, and health-related quality of life (HRQOL); and (3) the relationship between objective and subjective outcomes. In this open nonrandomized experimental study, 22 patients, median age 71 years, with severe HF were studied before and after 3 months of receiving nocturnal oxygen. The measures used were overnight polysomnography, echocardiography, 6-minute walk test, self-assessed sleep difficulties (Uppsala Sleep Inventory-HF), daytime sleepiness (Epworth Sleepiness Scale), and HRQOL (36-Item Short Form Health Survey and Minnesota Living with Heart Failure Questionnaire). SDB, with a 90% dominance of central sleep apnea, occurred in 41% of the patients with severe HF before intervention. After intervention, functional capacity improved for both the whole group of patients with HF (P < .01) and HF patients with SDB (P < .05). No improvements regarding cardiac function, objective sleep, subjective sleep, or SDB were seen, except for a decrease of ≥4% desaturations (P < .05). HRQOL did not differ significantly between HF patients with and without SDB before or after intervention with nocturnal oxygen. Long-term nocturnal oxygen treatment improved functional capacity in patients with severe HF, with or without SDB. No improvements were seen regarding sleep, daytime sleepiness, SDB, cardiac function, or HRQOL.

Acoustic Analysis of a Mechanical Circulatory Support

Mechanical circulatory support technology is continually improving. However, adverse complications do occur with devastating consequences, for example, pump thrombosis that may develop in several parts of the pump system. The aim of this study was to design an experimental clot/thrombosis model to register and analyze acoustic signals from the left ventricular assist device (LVAD) HeartMate II (HMII) (Thoratec Corporation, Inc., Pleasanton, CA, USA) and detect changes in sound signals correlating to clots in the inflow, outflow, and pump housing. Using modern telecom techniques, it was possible to register and analyze the HMII pump-specific acoustic fingerprint in an experimental model of LVAD support using a mock loop. Increase in pump speed significantly (P < 0.005) changed the acoustic fingerprint at certain frequency (0–23 000 Hz) intervals (regions: R1–3 and peaks: P1,3–4). When the ball valves connected to the tubing were narrowed sequentially by ∼50% of the inner diameter (to mimic clot in the out- and inflow tubing), the frequency spectrum changed significantly (P < 0.005) in P1 and P2 and R1 when the outflow tubing was narrowed. This change was not seen to the same extent when the lumen of the ball valve connected to the inflow tube was narrowed by ∼50%. More significant (P < 0.005) acoustic changes were detected in P1 and P2 and R1 and R3, with the largest dB figs. in the lower frequency ranges in R1 and P2, when artificial clots and blood clots passed through the pump system. At higher frequencies, a significant change in dB figs. in R3 and P4 was detected when clots passed through the pump system. Acoustic monitoring of pump sounds may become a valuable tool in LVAD surveillance.

Myocardial tissue motion influence on laser Doppler perfusion monitoring using tissue Doppler imaging

Tissue motion of the beating heart generates large movement artifacts in the laser Doppler perfusion monitoring (LDPM) signal. The aim of the study was to use tissue Doppler imaging (TDI) to localise intervals during the cardiac cycle where the influence of movement artifacts on the LDPM signal is minimum. TDI velocities and LDPM signals were investigated on three calves, for normal heartbeat and during occlusion of the left anterior descending coronary artery. Intervals of low tissue velocity (TDIint<1 cm s−1) during the cardiac cycle were identified. During occlusion, these intervals were compared with low LDPM signal intervals (LDPMint<50% compared with baseline). Low-velocity intervals were found in late systole (normal and occlusion) and late diastole (normal). Systolic intervals were longer and less sensitive to heart rate variation compared with diastolic ones. The overlap between LDPMint and TDIint in relation to TDIint length was 84±27% (n=14). The LDPM signal was significantly (p<0.001, n=14) lower during occlusion if calculated during minimum tissue motion inside TDIint), compared with averaging over the entire cardiac cycle without taking tissue motion into consideration. In conclusion, movement artifacts are reduced if the LDPM signal is correlated to the ECG and investigated during minimum wall motion. The optimum interval depends on the application; late systole and late diastole can be used.

Clinical implications of physiological flow adjustment in continuous-flow left ventricular assist devices.

There is increasing evidence for successful management of end-stage heart failure with continuous-flow left ventricular assist device (CF-LVAD) technology. However, passive flow adjustment at fixed CF-LVAD speed is susceptible to flow balancing issues as well as adverse hemodynamic effects relating to the diminished arterial pulse pressure and flow. With current therapy, flow cannot be adjusted with changes in venous return, which can vary significantly with volume status. This limits the performance and safety of CF-LVAD. Active flow adjustment strategies have been proposed to improve the synchrony between the pump and the native cardiovascular system, mimicking the Frank–Starling mechanism of the heart. These flow adjustment strategies include modulation by CF-LVAD pump speed by synchrony and maintenance of constant flow or constant pressure head, or a combination of these variables. However, none of these adjustment strategies have evolved sufficiently to gain widespread attention. Herein we review the current challenges and future directions of CF-LVAD therapy and sensor technology focusing on the development of a physiologic, long-term active flow adjustment strategy for CF-LVADs.

A single center experience with the HeartMate II (TM) Left Ventricular Assist Device (LVAD)

Objectives: Left ventricular assist devices (LVAD), used in the setting bridge-to-transplantation and destination therapy, for patients with deteriorating severe heart failure are continuously developing. The second generation, the axial flow pumps, have been introduced since some years. Design: Eleven consecutive patients, seven male, with severe heart failure due to ischemic cardiomyopathy (n=5), dilated cardiomyopathy (n=5) and cytotoxic ethiology (n=1) were implanted with the HeartMate-II™. They were preoperatively treated with inotropic support (n=9), ventricular assist device (n=2) and mechanical ventilation (n=4). Results: Eight patients were bridged to transplant after median 155 days (range, 65 to 316 days). One patient is ongoing for 748 days, intended for destination therapy. Ten of eleven patients were discharged after median 64 days (range, 40 to 105 days). Four patients were reoperated due to bleeding. Two embolic events were recorded. One perioperative death. Conclusion: Eleven HM-II™ LVADs have been implanted in our institution with good early results. Eight patients were successfully bridged to heart transplantation. One patient is intended for destination therapy and is ongoing since November 2006. In these severely ill patients, this technique offers a good chance surviving until heart transplantation. In selected cases the technique also offers the possibility of a permanent support and longevity.

Long-term left ventricular support in patients with a mechanical aortic valve

Abstract Objectives. The presence of a mechanical prosthesis has been regarded as an increased risk of thromboembolic complications and as a relative contraindication for a left ventricular assist device (LVAD). Five patients in our center had a mechanical aortic valve at the time of device implantation and were studied regarding thromboembolic complications. Design. Five patients operated upon with an LVAD (1 HeartMate I™, 4 HeartMate II™) between 2002 and 2011 had a mechanical aortic valve at the time of implantation. The first patient had a patch closure of the aortic valve. In four patients, the prosthesis was left in place. Anticoagulants included aspirin, warfarin, and clopidogrel. Results. The average and accumulated treatment times were 150 and 752 days, respectively. Three of the five patients showed early signs of valve thrombosis on echo with concomitant valve dysfunction. Four patients were transplanted without thromboembolic events during pump treatment. One patient died from a hemorrhagic stroke after 90 days on the LVAD. Conclusions. The strategy of leaving a mechanical heart valve in place at the time of LVAD implantation in five patients led to valvular thrombosis in three but did not provoke embolic events. It increased the complexity of postoperative anticoagulation.

Axial flow pump treatment during myocardial depression in calves : an invasive hemodynamic and echocardiographic tissue Doppler study.

The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of &bgr;-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.

Endovascular stenting of an outflow graft thrombosis in a continuous-flow left ventricular assist device.

We report the endovascular stenting of an outflow tract thrombosis in a left ventricular assist device in a patient with relative contraindications to sternotomy and pump exchange. This report highlights the importance of simultaneous prevention of stroke using filter devices in the common carotid arteries.

Left Atrial Pressure Monitoring With an Implantable Wireless Pressure Sensor Following Implantation of a Left Ventricular Assist Device.

After implantation of a continuous-flow left ventricular assist device (LVAD), left atrial pressure (LAP) monitoring allows for the precise management of intravascular volume, inotropic therapy, and pump speed. In this case series of 4 LVAD recipients, we report the first clinical use of this wireless pressure sensor for the long-term monitoring of LAP during LVAD support. A wireless microelectromechanical system pressure sensor (Titan, ISS Inc., Ypsilanti, MI) was placed in the left atrium in four patients at the time of LVAD implantation. Titan sensor LAP was measured in all four patients on the intensive care unit and in three patients at home. Ramped speed tests were performed using LAP and echocardiography in three patients. The left ventricular end-diastolic diameter (cm), flow (L/min), power consumption (W), and blood pressure (mm Hg) were measured at each step. Measurements were performed over 36, 84, 137, and 180 days, respectively. The three discharged patients had equipment at home and were able to perform daily recordings. There were significant correlations between sensor pressure and pump speed, LV and LA size and pulmonary capillary wedge pressure, respectively (r = 0.92–0.99, p < 0.05). There was no device failure, and there were no adverse consequences of its use.

Young woman with breast cancer and cardiotoxicity with severe heart failure treated with a HeartMate IITM for nearly 6 years before heart transplantation.

Cardiotoxicity is a multifactorial problem, which has emerged with the improvement of cancer therapies and survival. Heart transplantation is relatively contraindicated in patients with breast cancer, until at least 5 years after complete remission. We present a case where a young woman who in 2001, at the age of 31, was diagnosed with breast cancer. She was considered cured, but 4 years later she suffered a relapse. During her second treatment, in 2006, she suffered from severe heart failure. She received a HeartMate II, as a long-term bridge to transplantation and 6 years later she was successfully transplanted. In this case report we discuss the use of mechanical circulatory support in cancer patients with drug-induced heart failure.