Increased pulse-wave velocity in patients with anxiety: implications for autonomic dysfunction

Decreased vagal function is associated with vascular dysfunction. In this study, we compared vascular indices and correlated heart rate and QT variability measures with vascular indices in patients with anxiety disorders and normal controls. We compared age- and sex-matched controls (n=23) and patients with anxiety (n=25) using the Vascular Profiler (VP-1000; Colin Medical Instruments, Japan), approved by the US Food and Drug Administration. Using this machine, we obtained ankle and brachial blood pressure (BP) in both arms (brachial), both legs (ankle), and carotid artery, and lead I electrocardiogram (ECG) and phonocardiogram. Using these signals, pulse-wave velocity (PWV), and arterial stiffness index % and preejection period can be calculated. We also obtained ECG sampled at 1000 Hz in lead II configuration in supine posture to obtain beat-to-beat interbeat interval (R-R) and QT interval variability for 256 s. Patients with anxiety had significantly higher carotid mean arterial pressure (MAP) %, brachial-ankle PWV (BAPWV), arterial stiffness index %, MAP, and diastolic BP of the extremities compared to controls. We found significant negative correlations (r values from .4 to .65; P<.05 to .007) between R-R interval high-frequency (0.15-0.5 Hz) power (which is an indicator of cardiac vagal function), and increased BAPWV and systolic BP of the extremities only in patients. We were unable to find such correlations in controls. We also found significant positive correlations between QT variability index (a probable indicator of cardiac sympathetic function) and MAP of the extremities and BAPWV only in the patient group. These findings suggest an important association between decreased vagal and increased sympathetic function, and decreased arterial compliance and possible atherosclerotic changes and increased BP in patients with anxiety.

Evaluation of blood pressure changes using vascular transit time

Imbalance of the human haemodynamic system can provide a prognosis of syncope, dizziness or hypertension. This can be assessed by monitoring its responses to postural change. Examining variations in blood pressure (BP) is deemed an effective means to identify symptoms of this associated condition. However, conventional methods do not promote prolonged monitoring due to the discomfort caused to patients. Established correlations between BP and pulse wave transmission have shown its usefulness in clinical applications. In this study, photoplethysmography and phonocardiography were used to estimate BP changes via observed variations in delay transmission or vascular transit time (VTT) at the upper limb. Thirty-one healthy adults (21 male) were recruited to perform three test activities, namely the arm held at heart level, fully raised up and held down. Association of the three BP indices and heart rate variations with transit time changes was then computed. The results showed that observed VTT changes were related to systolic BP (R(2) = 0.820; p < 0.05), diastolic BP (R(2) = 0.517; p < 0.05), mean arterial pressure (R(2) = 0.673; p < 0.05) and heart rate (R(2) = 0.000; p > 0.05). As systolic BP had the strongest correlation, a regression equation was formulated to associate the two parameters. The non-invasive measuring nature of VTT can be more accommodating to patients, especially during continual monitoring. Moreover, it has the added advantage that the pre-ejection period is not included in its time-related derivations.

Detection of microbubble formation during radiofrequency ablation using phonocardiography

AIMS

To detect and characterize the acoustic energy generated by microbubble (MB) formation in an isolated tissue preparation. MB formation during radiofrequency (RF) ablation indicates excessive tissue heating and may precede explosive 'pops'. Currently, MB formation can only be detected with echocardiography. We hypothesized that MB formation can be detected with high-sensitivity phonocardiography.

METHODS AND RESULTS

In a saline bath, RF lesions were created in sections of porcine left ventricle, using a 4 mm tip irrigated catheter. MB formation was visualized with an echocardiography probe. In 20 preparations, RF energy was begun at 25 W and increased by 5 W every 20 s until a pop occurred. A high-sensitivity computerized phonocardiography transducer with frequency bandwidth of 2 kHz and system noise -90 dB (SonoMedica, Inc., Vienna, VA, USA) was coupled to the external glass wall of the bath. In 15 of 20 (75%) preparations, a characteristic acoustic signature corresponding to MB formation was noted before the pop. These signals were within the 600-2000 Hz range and had an intensity range of 10-40 dB. The earliest MB and acoustic signals occurred 51.3+/-51.5 s before the pop. The acoustic signals continued intermittently up to 10.3+/-12.9 s before the pop.

CONCLUSION

The acoustic energy created by MB formation can be detected in an isolated tissue preparation, using a computer-based phonocardiography system. Characteristic acoustic signatures are present before pops and correspond to MB formation. Acoustic monitoring for MB formation may allow for the titration of cooled RF ablation without echocardiography.

Competency in cardiac examination skills in medical students, trainees, physicians, and faculty: a multicenter study

BACKGROUND

Cardiac examination is an essential aspect of the physical examination. Previous studies have shown poor diagnostic accuracy, but most used audio recordings, precluding correlation with visible observations. The training spectrum from medical students (MSs) to faculty has not been tested, to our knowledge.

METHODS

A validated 50-question, computer-based test was used to assess 4 aspects of cardiac examination competency: (1) cardiac physiology knowledge, (2) auditory skills, (3) visual skills, and (4) integration of auditory and visual skills using computer graphic animations and virtual patient examinations (actual patients filmed at the bedside). We tested 860 participants: 318 MSs, 289 residents (225 internal medicine and 64 family medicine), 85 cardiology fellows, 131 physicians (50 full-time faculty, 12 volunteer clinical faculty, and 69 private practitioners), and 37 others.

RESULTS

Mean scores improved from MS1-2 to MS3-4 (P = .003) but did not improve or differ significantly among MS3, MS4, internal medicine residents, family medicine residents, full-time faculty, volunteer clinical faculty, and private practitioners. Only cardiology fellows tested significantly better (P<.001), and they were the best in all 4 subcategories of competency, whereas MS1-2 were the worst in the auditory and visual subcategories. Participants demonstrated low specificity for systolic murmurs (0.35) and low sensitivity for diastolic murmurs (0.49).

CONCLUSIONS

Cardiac examination skills do not improve after MS3 and may decline after years in practice, which has important implications for medical decision making, patient safety, cost-effective care, and continuing medical education. Improvement in cardiac examination competency will require training in simultaneous audio and visual examination in faculty and trainees.

Relationship Between Accurate Auscultation of a Clinically Useful Third Heart Sound and Level of Experience

BACKGROUND

Poor performance by physicians-in-training and interobserver variability between physicians have diminished clinicians' confidence in the value of the third heart sound (S3).

METHODS

To determine whether auscultation of a clinically useful S3 improves with advancing levels of experience, we performed a prospective, blinded, observational study of 100 patients undergoing left-sided heart catheterization. Patients underwent blinded auscultation by 4 physicians (each from 1 of 4 different levels of experience), phonocardiography, measurement of blood B-type natriuretic peptide levels, echocardiography for measurement of left ventricular ejection fraction, and cardiac catheterization for measurement of left ventricular end-diastolic pressure.

RESULTS

Whereas residents' and interns' auscultatory findings demonstrated no significant agreement with phonocardiographic findings, an S3 auscultated by cardiology fellows (kappa = 0.37; P<.001) and cardiology attendings (kappa = 0.29; P = .003) agreed with phonocardiographic findings. Although the sensitivities of the S3 were low (13%-52%) for identifying patients with abnormal measures of left ventricular function, the specificities were high (85%-95%), with the best test characteristics exhibited by phonocardiography and more experienced physicians. The S3 detected by attendings and fellows was superior in distinguishing an elevated B-type natriuretic peptide level, a depressed left ventricular ejection fraction, or an elevated left ventricular end-diastolic pressure (P = .002-.02 for attendings and .02-.03 for fellows) compared with residents (P = .02-.47) or interns (P = .09-.64).

CONCLUSIONS

The S3 auscultated by more experienced physicians demonstrated fair agreement with phonocardiographic findings. Although correlations were superior for phonocardiography, the associations between the S3 and abnormal markers of left ventricular function improved with each level of auscultator experience.

Heart murmur and anaemia in the pediatric population

Innocent heart murmurs are hearth murmurs that occur in patients with a normal heart structure. They do not represent a disease of the heart and vascular system, and should not be treated as such. Iron-deficiency anaemia often causes, along with other symptoms, systolic heart murmurs and tachycardia. It appears in children of all ages representing a most common haematological paediatric disease. To establish the influence of iron-deficiency anaemia on genesis of innocent murmurs and to compare auscultatory and phono-electrocardiographic findings in patients with anaemia and heart murmurs before and after iron therapy. The study includes 120 patients with innocent heart murmurs that have been auscultated at cardio-rheumatic outpatient department of Pediatric Clinic of the Clinical Center of the University of Sarajevo, during the period from 01/01/2004 to 31/12/2004. Further diagnostic procedure, i.e. laboratory tests, diagnosed iron-deficiency anaemia in 30/120 patients. These patients have been followed in this study. 22/30 patients had systolic murmur I/II intensity of Levin scale; 8/30 patients had II/VI systolic murmurs of intensity by Levin. The highest number of examinees had 0-1 years of age, and in this group the number of boys was higher than the number of girls (M: F = 12:4). During the auscultatory and phono-ECG examinations of murmurs, 6 patients had haemoglobin values less than 95 g/l, which corresponds to an average and severe type of anaemia. 24 patients had haemoglobin values between 95 and 110 g/l, which corresponds to benign type of anaemia. The most numerous were patients aged between 0 - 1 year (3 patients with hemoglobin value Hb < 95 g/l, 13 patients with hemoglobin value Hb 95-110 g/l). All patients were treated with iron medicaments. After three months, clinical and laboratory re-evaluation was performed and it has demonstrated that after iron therapy 24 patients had level of a haemoglobin Hb >110 g/l and 6 patients had haemoglobin levels between 95 and 110 g/l. By auscultatory and phono-ECG examinations, murmurs of a level of intensity I/II was registered in only one child, while in the other 29 patients there were not any registered heart murmurs. Diagnosis of anaemia in the paediatric population group delays definitive diagnosis of heart murmurs. Innocent murmurs in children with sideropenic anaemia occur as its consequence. After adequately conducted iron therapy, i.e. cured anaemia, heart murmurs were not auscultated.

Time-frequency analysis of the second cardiac sound in phonocardiogram signals

The paper is concerned with the analysis of the phonocardiogram signals (PCG) in the time-frequency domain. Three techniques are studied and evaluated in PCG signal analysis. These are the short time Fourier transform (STFT), the Wigner distribution function (WD) and the continuous wavelet transforms (CWTs). The analysis is first carried out on the second cardiac sound (S2) in order to show the aptitude of each method in distinguishing the internal components of this sound. The results we obtain show that the STFT cannot detect the two internal components of S2 (A2 and P2, respectively, the aortic and pulmonary components). The WD can provide time-frequency characteristics of S2, but with insufficient diagnostic information: the two components are not accurately detected and appear to be only one component. It is found that the CWT (it can also provide the time-frequency characteristic of S2) is capable of detecting its two components, A2 and P2, allowing therefore the measurement of the delay between them. This delay, called the split, is very important in the diagnosis of many pathological cases, as it is emphasized in the results we obtain by applying the CWT on different pathological cases (mitral stenosis, pulmonary stenosis and atrial septal defect).

Modified scaled Fourier linear combiner in thoracic impedance cardiography

New filtering algorithms; a modified scaled Fourier linear combiner (mSFLC) and a modified ensemble averaging (mEA) are proposed to remove the phase distortion of the impedance waveform caused by SFLC. Performance of the filters is assessed from the shape of the filtered waveform and the estimation of systolic time intervals. It was found that the mSFLC and mEA could compensate for drawbacks of the SFLC and precisely reproduce the impedance waveforms; however, misinterpretation and attenuation in the cardiac variables may be caused when abrupt changes or irregularities occur in the source waveform.

Detection of the third heart sound using a tailored wavelet approach: method verification

Heart sounds can be considered as mechanical fingerprints of myocardial function. The third heart sound normally occurs in children but disappears with maturation. The sound can also appear in patients with heart failure. The sound is characterised by its low-amplitude and low-frequency content, which makes it difficult to identify by the traditional use of the stethoscope. A wavelet-based method has recently been developed for detection of the third heart sound. This study investigated if the third heart sound could be identified in patients with heart failure using this detection method. The method was also compared with auscultation using conventional phonocardiography and with characterisation of the patients with echocardiography. In the first study, 87% of the third heart sounds were detected using the wavelet method, 12% were missed, and 6% were false positive. In study 2, the wavelet-detection method identified 87% of the patients using the third heart sound, and regular phonocardiography identified two (25%) of the subjects.

Familial biventricular myocardial noncompaction associated with Ebstein's malformation

BACKGROUND

Noncompaction of the ventricular myocardium is a rare congenital cardiomyopathy characterized by numerous excessively prominent trabeculations and deep intertrabecular recesses. Noncompaction of the ventricular myocardium is most often an isolated cardiac malformation presenting as a sporadic disease. Associated cardiac anomalies are present in some patients. We report a family with three adult males from consecutive generations having a biventricular form of noncompaction of the myocardium. Two of the patients have an associated Ebstein's malformation of the tricuspid valve.

METHODS

Clinical evaluation and follow-up, electrocardiography, echocardiography, heart catheterization, coronary angiography, contrast cineventriculography, and magnetic resonance imaging.

RESULTS AND CONCLUSIONS

The association of noncompaction of the ventricular myocardium and Ebstein's malformation has not been reported so far. We believe that both defects were caused by a developmental arrest of the right ventricular myocardium. Echocardiography is the diagnostic modality of choice in patients and in the male relatives, irrespective of their clinical status. Thromboembolic events, cardiac rhythm disorders and heart failure mandate treatment. Anticoagulation treatment and implantation of cardioverter-defibrillator pacemaker have to be strongly considered in these patients.

Effects of high intensity resistance training on arterial stiffness and wave reflection in women

BACKGROUND

Cross-sectional studies reported that chronic resistance training is associated with arterial stiffening in men. These findings are in marked contrast to those found with aerobic exercise and may have important clinical relevance with regard to cardiovascular disease risk. However, the effect of resistance training on arterial stiffness has not been confirmed by interventional studies nor has this relation been investigated in women.

METHODS

To determine whether a strength training program increases regional and central arterial stiffness in women, 23 healthy young women (29+/-1 years; mean+/-SD) participated in a high-intensity strength and power training program for 11 weeks. Ten other women (27+/-2 years) served as time controls.

RESULTS

In the intervention group, one repetition maximal strength increased 12% to 17% (P<.0001), and leg fat-free mass (via DEXA) increased significantly. Brachial blood pressure (BP) and fasting plasma lipid and lipoprotein concentrations did not change across the 11 weeks. Carotid augmentation index, a measure of arterial wave reflection and arterial stiffness, increased from -8%+/-13% to 1%+/-18% (P<.05), and carotid-femoral pulse wave velocity increased (791+/-88 v 833+/-96 cm/sec; P<.05). There were no changes in femoral-ankle pulse wave velocity, a segmental measure of peripheral arterial stiffness.

CONCLUSIONS

We concluded that a high-intensity resistance training program increases arterial stiffness and wave reflection in young healthy women. Our present interventional results are consistent with the previous cross-sectional studies in men in which high-intensity strength training is associated with arterial stiffening.

A classifier based on the artificial neural network approach for cardiologic auscultation in pediatrics

OBJECTIVE

This research work was aimed at developing a reliable screening device for diagnosis of heart murmurs in pediatrics. This is a significant problem in pediatric cardiology because of the high rate of incidence of heart murmurs in this population (reportedly 77-95%), of which only a small fraction arises from congenital heart disease. The screening devices currently available (e.g. chest X-ray, electrocardiogram, etc.) suffer from poor sensitivity and specificity in detecting congenital heart disease. Thus, patients with heart murmurs today are frequently assessed by consultation as well with advanced imaging techniques. The most prominent among these is echocardiography. However, echocardiography is expensive and is usually only available in healthcare centers in major cities. Thus, for patients being evaluated with a heart murmur, developing a more accurate screening device is vital to efforts in reducing health care costs.

METHODS AND MATERIAL

The data set was collected from incoming pediatrics at the cardiology clinic of The Children's Hospital (Denver, Colorado), on whom echocardiography had been performed to identify congenital heart disease. Recordings of approximately 10-15s duration were made at 44,100Hz and the average record length was approximately 60,000 points. The best three cycles with respect to signal quality sounds were extracted from the original recording. The resulting data comprised 241 examples, of which 88 were examples of innocent murmurs and 153 were examples of pathological murmurs. The selected phonocardiograms were subject to the digital signal processing (DSP) technique of fast Fourier transform (FFT) to extract the energy spectrum in frequency domain. The spectral range was 0-300Hz at a resolution of 1Hz. The processed signals were used to develop statistical classifiers and a classifier based on our in-house artificial neural network (ANN) software. For the latter, we also tried enhancements to the basic ANN scheme. These included a method for setting the decision-threshold and a scheme for consensus-based decision by a committee of experts.

RESULTS

Of the different classifiers tested, the ANN-based classifier performed the best. With this classifier, we were able to achieve classification accuracy of 83% sensitivity and 90% specificity in discriminating between innocent and pathological heart murmurs. For the problem of discrimination between innocent murmurs and murmurs of the ventricular septal defect (VSD), the accuracy was higher, with sensitivity of 90% and specificity of 93%.

CONCLUSIONS

An ANN-based approach for detection and identification of congenital heart disease in pediatrics from heart murmurs can result in an accurate screening device. Considering that only a simple feature set was used for classification, the results are very encouraging and point out the need for further development using improved feature set with more potent diagnostic variables.

Association between phonocardiographic third and fourth heart sounds and objective measures of left ventricular function

CONTEXT

The third (S3) and fourth (S4) heart sounds detected by phonocardiography are considered to represent the criterion standards of the gallop sounds, but their test characteristics have not been explored.

OBJECTIVE

To determine the diagnostic test characteristics of the S3 and S4 for prediction of left ventricular dysfunction using a computerized heart sound detection algorithm.

DESIGN, SETTING, AND PARTICIPANTS

Prospective study of 90 adult patients undergoing elective left-sided heart catheterization at a single US teaching hospital between August 2003 and June 2004. The mean age was 62 (SD, 13) years (range, 24-90 years) and 61 (68%) were male. Within a 4-hour period, participants underwent computerized heart sound phonocardiographic analysis, cardiac catheterization, transthoracic echocardiography, and blood sampling for assessment of an S3/S4, left ventricular end-diastolic pressure (LVEDP), left ventricular ejection fraction (LVEF), and B-type natriuretic peptide (BNP), respectively.

MAIN OUTCOME MEASURES

Diagnostic test characteristics of the computerized phonocardiographic S3 and S4 using markers of left ventricular function as criterion standards.

RESULTS

Mean (SD) LVEDP was significantly elevated (18.4 [6.9] mm Hg vs 12.1 [7.3] mm Hg; P<.001), mean (SD) LVEF was reduced (49.4% [20.2%] vs 63.6% [14.8%]; P<.001), and median (interquartile range) BNP was elevated (330 [98-1155] pg/mL vs 86 [41-192] pg/mL; P<.001) in those with an S3, S4, or both compared with patients without a diastolic heart sound. The sensitivities of these heart sounds to detect an elevated LVEDP, reduced LVEF, or elevated BNP were 41%, 52%, and 32% for an S3, and 46%, 43%, and 40% for an S4, respectively. For abnormal levels of the same markers of ventricular function, the specificities of the S3 were 92%, 87%, and 92%, while the specificities of the S4 were 80%, 72%, and 78%, respectively.

CONCLUSIONS

Neither the phonocardiographic S3 nor the S4 is a sensitive marker of left ventricular dysfunction. The phonocardiographic S3 is specific for left ventricular dysfunction and appears to be superior to the moderate specificity of the phonocardiographic S4.

Usefulness of a new sound spectral averaging technique to distinguish an innocent systolic murmur from that of aortic stenosis

We present a new method to record and display heart sounds that uses a hand-held computer and stethoscopic recording device. It allows for rapid spectral and waveform displays of murmurs and provides a means for signal averaging of spectral frequency content. Compared with aortic stenosis, innocent murmurs primarily contain frequencies of <300 Hz and persist for a shorter duration at the upper-frequency levels. This method provides for rapid characterization of innocent murmurs, a means for comparison with other murmurs, and transmission of acoustic data to distant sites.

[Long-surviving patient with isolated absent pulmonary valve syndrome: a case report]

A 79-year-old woman was admitted for exertional dyspnea in September 2001. She had begun to experience unusual fatigue from the age of 40 years. Cardiac examination revealed a single S2, Levine grade II/VI presystolic murmur in the 5th left sternal border, and a right parasternal impulse. Echocardiography showed dilated right chambers and absence of pulmonary valve leaflets. Doppler echocardiography at the pulmonary annulus revealed a 'to and fro' pattern. Cardiac catheterization indicated the same diastolic pressures in the pulmonary artery and right ventricle. The diagnosis was absent pulmonary valve syndrome. Administration of a diuretic agent resulted in almost immediate improvement of symptoms. Absent pulmonary valve syndrome, generally associated with tetralogy of Fallot, often causes severe respiratory failure or right heart failure during infancy. A case of such long survival without associated cardiac anomalies is very rare.

Myocardial Acceleration During Isovolumic Contraction

Background— Acceleration of the mitral ring during isovolumic contraction has been proposed as a load-independent index of global left ventricular (LV) contractility. This study investigates whether myocardial isovolumic acceleration (IVA) reflects regional contractility.

Methods and Results— In acutely instrumented, anesthetized dogs, we measured LV pressure, myocardial long-axis velocities, and IVA by tissue Doppler imaging (TDI) and sonomicrometry at different levels of global LV contractility and preload and during regional myocardial ischemia (reduced flow in the left anterior descending coronary artery). Dobutamine caused dose-dependent increments in IVA from 3.6±0.6 (mean±SEM) to a maximum of 7.1±1.4 m/s 2 ( P <0.01) by TDI, and there were parallel increments in LV dP/dt max ( P <0.01). However, volume loading decreased IVA from 3.6±0.6 to 2.5±0.4 m/s 2 ( P <0.05), whereas LV dP/dt max was unchanged, and LV pressure–segment length loop analysis confirmed unchanged regional contractility. During myocardial ischemia, sonomicrometry indicated severely depressed regional function, whereas IVA remained unchanged. These findings were confirmed when IVA was measured by sonomicrometry. In contrast to peak ejection velocity that increased from apex toward the LV base, peak IVC velocity was maximum midway between apex and base. The onset of IVA coincided with onset of the first heart sound by phonocardiography. Peak IVA occurred at a LV pressure of 14±1 mm Hg, ie, close to end-diastole.

Conclusions— There was no consistent relationship between peak IVA and regional myocardial contractility. Peak IVA was markedly load dependent and did not reflect impaired myocardial function during ischemia. Peak IVA may reflect late-diastolic events and possibly wall oscillations that are related to global LV function. Peak IVA seems to have limited potential in the assessment of regional myocardial function.

Acoustic diagnosis of aortic stenosis

BACKGROUND AND AIM OF THE STUDY

Phonocardiography is a promising non-invasive diagnostic tool for the assessment of aortic stenosis (AS), and time-frequency representation is a potential tool to extract information from the phonocardiogram (PCG) signal. The study aim was to develop an acoustical method to predict the severity of AS.

METHODS

Normalized continuous wavelet transform (NCWT) and fast Fourier Transform (FFT) were used to perform a spectral analysis of the PCG signal. A multi-peak detection algorithm was developed to determine the dominant frequency (DF) of systolic murmurs (SM). The spectral ratio of the SM, integration of the NCWT of SM (SI), and combined information of SM and second heart sound, were also calculated.

RESULTS

The DF correlated best with the hemodynamic data: r = -0.72 with aortic valve (AV) area; r = 0.63 with maximal blood velocity through the AV; and r = 0.57 with mean pressure gradient across the AV. Based on DF and SI data, the study subjects (n = 59) were classified into three categories: severe AS; moderate AS; and other cases. The acoustical and echo classifications were in agreement in 50 subjects (85%).

CONCLUSION

The acoustical method developed cannot predict accurately the severity of AS, but is valuable when conducting a screening classification before an invasive method is used.

Strategy and tactics of instrumental examination of patients with thoracic and thoracoabdominal aortic aneurysm

The paper gives a detailed characterization and describes the importance of instrumental methods for examination of patients in the diagnosis of thoracic and thoracoabdominal aortic aneurysms. Provides a differentiated protocol of the examination of patients as dependent on the clinical course, disease stage and nemodynamic stability of the patient's status. Delineates the tactics of the examination of patients with acute and chronic dissection of the proximal and distal segments of the aorta as dependent on hemodynamic stability. Emphasis is laid on the key role of computed tomography and magnetic resonance tomography in the diagnosis of aortic aneurysms.

The long-term results of surgical treatment of ascending aortic aneurysms

The paper summarizes an experience with surgical treatment of ascending aortic aneurysms, gained at the Russian Scientific Center of Surgery, RAMS. Ninety-two patients operated on for the complicated and uncomplicated forms of ascending aortic aneurysms were entered into the study. A comparative analysis was made of the long-term results of different types of surgical interventions. The authors demonstrate the advantages of operations using valve-containing conduits and of operations which consisted in graded intima-sparing resection of aortic aneurysm and eco-prosthetics. The survival of patients over the period as long as 12 years after operation accounted for 86%.

Development of an Electro-stethoscope System and Design of an Optimum Filter Based on Tissue Sound Transmission for Noninvasive Early Diagnosis of Malfunction of an Implanted Mechanical Total Artificial Heart

Early diagnosis of the malfunction of a mechanical artificial heart implanted in a patient who has been discharged from hospital is very important. We have developed an electro-stethoscope system that enables the malfunction of an artificial heart to be detected from the analysis of sound signals from the artificial heart. The sound data can be transmitted to a hospital via a mobile telephone or the Internet, so that doctors can examine the condition of the artificial heart. The optimum frequency characteristics of a low-pass filter for the elimination of ambient sound through the electro-stethoscope casing were obtained by simulating sound transmission through tissue. We evaluated the usefulness of the electro-stethoscope system using a goat in which an undulation pump total artificial heart had been implanted. A frequency analysis of the sound signal provided information on the degree of degradation of each mechanical component of the artificial heart. The results of this study showed that the electro-stethoscope system is useful for the early detection of the malfunction of an artificial heart at home, and that the use of the system contributes to improvement in the quality of life of patients.