This third edition of what has now become a well-established textbook in cardiovascular medicine is again edited by Dr Eugene Braunwald with the assistance of 65 other authors who read like a Who's Who of American Cardiology. Since the second edition, 12 new chapters have been added or substituted and others have been significantly revised. The first volume includes Part I on "Examination of the Patient" and Part II on "Normal and Abnormal Circulatory Function." The second volume deals with specific diseases. Part III, "Diseases of the Heart, Pericardium and Vascular System," includes new sections on "Risk Factors for Coronary Artery Disease," "The Pathogenesis of Atherosclerosis," and "Interventional Catheterization Techniques." Part IV, "Broader Perspectives on Heart Disease and Cardiologic Practice," includes new chapters on "Genetics and Cardiovascular Disease," "Aging in Cardiac Disease," and "Cost Effective Strategies in Cardiology." The last 200 pages of the book (Part V) are devoted to

Heart Disease: A Textbook of Cardiovascular Medicine

Heart Disease A Textbook of Cardiovascular Medicine

This paper reviews recent progress of portable short-range noncontact microwave radar systems for motion detection, positioning, and imaging applications. With the continuous advancements of modern semiconductor technologies and embedded computing, many functionalities that could only be achieved by bulky radar systems in the past are now integrated into portable devices with integrated circuit chips and printed circuits boards. These portable solutions are able to provide high motion detection sensitivity, excellent signal-to-noise ratio, and satisfactory range detection capability. Assisted by on-board signal processing algorithms, they can play important roles in various areas, such as health and elderly care, veterinary monitoring, human-computer interaction, structural monitoring, indoor tracking, and wind engineering. This paper reviews some system architectures and practical implementations for typical wireless sensing applications. It also discusses potential future developments for the next-generation portable smart radar systems.

A Review on Recent Progress of Portable Short-Range Noncontact Microwave Radar Systems

In this article, we briefly describe the design, construction, and functional verification of a hybrid multichannel fiber-optic sensor system for basic vital sign monitoring. This sensor uses a novel non-invasive measurement probe based on the fiber Bragg grating (FBG). The probe is composed of two FBGs encapsulated inside a polydimethylsiloxane polymer (PDMS). The PDMS is non-reactive to human skin and resistant to electromagnetic waves, UV absorption, and radiation. We emphasize the construction of the probe to be specifically used for basic vital sign monitoring such as body temperature, respiratory rate and heart rate. The proposed sensor system can continuously process incoming signals from up to 128 individuals. We first present the overall design of this novel multichannel sensor and then elaborate on how it has the potential to simplify vital sign monitoring and consequently improve the comfort level of patients in long-term health care facilities, hospitals and clinics. The reference ECG signal was acquired with the use of standard gel electrodes fixed to the monitored person's chest using a real-time monitoring system for ECG signals with virtual instrumentation. The outcomes of these experiments have unambiguously proved the functionality of the sensor system and will be used to inform our future research in this fast developing and emerging field.

A Non-Invasive Multichannel Hybrid Fiber-Optic Sensor System for Vital Sign Monitoring

This paper introduces heart sound detection by radar systems, which enables touch-free and continuous monitoring of heart sounds. The proposed measurement principle entails two enhancements in modern vital sign monitoring. First, common touch-based auscultation with a phonocardiograph can be simplified by using biomedical radar systems. Second, detecting heart sounds offers a further feasibility in radar-based heartbeat monitoring. To analyse the performance of the proposed measurement principle, 9930 seconds of eleven persons-under-tests’ vital signs were acquired and stored in a database using multiple, synchronised sensors: a continuous wave radar system, a phonocardiograph (PCG), an electrocardiograph (ECG), and a temperature-based respiration sensor. A hidden semi-Markov model is utilised to detect the heart sounds in the phonocardiograph and radar data and additionally, an advanced template matching (ATM) algorithm is used for state-of-the-art radar-based heartbeat detection. The feasibility of the proposed measurement principle is shown by a morphology analysis between the data acquired by radar and PCG for the dominant heart sounds S1 and S2: The correlation is 82.97 ± 11.15% for 5274 used occurrences of S1 and 80.72 ± 12.16% for 5277 used occurrences of S2. The performance of the proposed detection method is evaluated by comparing the F-scores for radar and PCG-based heart sound detection with ECG as reference: Achieving an F1 value of 92.22 ± 2.07%, the radar system approximates the score of 94.15 ± 1.61% for the PCG. The accuracy regarding the detection timing of heartbeat occurrences is analysed by means of the root-mean-square error: In comparison to the ATM algorithm (144.9 ms) and the PCG-based variant (59.4 ms), the proposed method has the lowest error value (44.2 ms). Based on these results, utilising the detected heart sounds considerably improves radar-based heartbeat monitoring, while the achieved performance is also competitive to phonocardiography.

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Radar-Based Heart Sound Detection

This paper presents a millimeter-wave radar in the 24-GHz ISM band for detection, tracking, and classification of human targets. Linear frequency modulation of the transmit signal and two receive antennas enable distance and angle measurements, respectively. Multiple consecutive frequency chirps are used for target velocity calculation. Hardware as well as firmware concepts of the proposed system are described in detail. Various algorithms for human detection and tracking are investigated and combined into a new signal processing routine optimized for compactness and low power to run on a microcontroller. In addition, a novel Doppler-compensated angle-of-arrival estimation method and a one-class support vector machine for human classification are proposed to further enhance the human detection and tracking performance. The achieved performances of the designed hardware and the implemented algorithm are verified in extensive measurements. The distance and angle errors of the realized radar sensor are at most 25 cm along a measurement range of 18 m and 10° for a two-sided angle sweep of 65°, respectively. The achieved range resolution is 0.9 m. The dedicated verifications of the most important signal processing routines are presented to verify their functionality and experiments with several human targets that illustrate the performance and limits of the overall tracking algorithm. It is shown that range, velocity, and angle of up to five humans are correctly detected and tracked. The presented one-class classifier successfully distinguishes the human targets from other quasi-static targets, such as trees and shadowing effects of human subjects on walls.

Human Target Detection, Tracking, and Classification Using 24-GHz FMCW Radar

Microwave technology plays a more important role in modern industrial sensing applications. Pushed by the significant progress in monolithic microwave integrated circuit technology over the past decades, complex sensing systems operating in the microwave and even millimeter-wave range are available for reasonable costs combined with exquisite performance. In the context of industrial sensing, this stimulates new approaches for metrology based on microwave technology. An old measurement principle nearly forgotten over the years has recently gained more and more attention in both academia and industry: the six-port interferometer. This paper reviews the basic concept, investigates promising applications in remote, as well as contact-based sensing and compares the system with state-of-the-art metrology. The significant advantages will be discussed just as the limitations of the six-port architecture. Particular attention will be paid to impairment effects and non-ideal behavior, as well as compensation and linearization concepts. It will be shown that in application fields, like remote distance sensing, precise alignment measurements, as well as interferometrically-evaluated mechanical strain analysis, the six-port architecture delivers extraordinary measurement results combined with high measurement data update rates for reasonable system costs. This makes the six-port architecture a promising candidate for industrial metrology.

Six-Port Based Interferometry for Precise Radar and Sensing Applications.

Radar systems enable a contactless, noninvasive method to simultaneously monitor the respiration and heart rate of a human target. To enhance the stability and accuracy of the detected heart rate, this letter introduces a Kalman filter-based tracking of the heartbeat signal. After providing a first rough estimation, the bandwidth of the applied band-pass filter is successively narrowed down, and the filter limits are steadily updated with respect to the current heart rate of the target. Measurement segments with random body movements are automatically identified and consequentially ignored for the Kalman filter update. The functionality of the proposed algorithm is proven by various verification measurements using a 60-GHz frequency-modulated continuous-wave radar system. The determined heart rates are compared to the output of a commercial chest belt. Measurement data with common breathing, as well as during breath-holding, were recorded for 14 different subjects.

Improved Contactless Heartbeat Estimation in FMCW Radar via Kalman Filter Tracking

Although a lot of research has been done into radar-based heartbeat detection over the past few years, it is still unknown which physiological effects truly underlie these measurement signals. This paper investigates the cardiovascular system, as well as the effects due to the antenna characteristics, and establishes a connection to the variety of heartbeat signals that can be found in comparable publications. For the first time, the cause of the diverging signal shapes is researched, revealing the locally specific pulse wave curves named sphygmograms. Three different types are investigated: the carotid, the venous, and the ventricle sphygmogram. Verification of the measured signal shapes is ensured by a laser sensor. Afterward, the influence of the filtering on the sphygmograms is researched, as well as the influence of the antenna characteristics on the radar signal. Finally, all novel insights are combined to substantiate the variety of published heartbeat signal curves.

Christoph Will

Papers

Radar-Based Heart Sound Detection

Human Target Detection, Tracking, and Classification Using 24-GHz FMCW Radar

Six-Port Based Interferometry for Precise Radar and Sensing Applications.

Improved Contactless Heartbeat Estimation in FMCW Radar via Kalman Filter Tracking

Local Pulse Wave Detection Using Continuous Wave Radar Systems