Hiroshi Sugiki

Wavelet analysis of bileaflet mechanical valve sounds

It has been reported that asynchronous leaflet closure in a bileaflet mechanical valve causes a split in the valve closing sound. We have previously reported that the continuous wavelet transform (CWT) with the Morlet wavelet as modified by Ishikawa (the Morlet wavelet) is the most suitable method among the CWTs for detecting a split in the bileaflet mechanical valve sound because this method can detect the highest frequency signal among the CWT methods with higher time resolution. This is the first article which discusses the acoustic properties of five types of bileaflet valves using the Morlet CWT. Similar behavior of the valve sound split intervals with wide fluctuations over consecutive heartbeats was found to be the common finding for all the bileaflet valves. This result suggests that fluctuation of the split interval proves the normal movement of both leaflets without movement disturbance. The mean differences in the split interval between these bileaflet valves were statistically significant, and the wavelet coefficients of the CWT showed characteristic scalographic patterns, such as a teardrop shape or a triangle beneath the split. However, these two findings gave no valuable information for the diagnosis of bileaflet valve malfunction. A split in the valve closing sound with a fluctuating interval was the common finding in these five normally functioning bileaflet valves, and careful observation of the splits behavior may be a key to diagnosis of bileaflet valve malfunction.

Bileaflet mechanical valve sound analysis using a continuous wavelet transform

Bileaflet mechanical valve closing sounds have splits, the duration of which is not constant in normally functioning valves. However, no reports have discussed the influences of valve malfunction on the split interval, neither have any studies discussed the fact that mechanical valve closing sound signals must be analyzed using a time-frequency analysis because they are nonstationary signals. The continuous wavelet transform (CWT), a time-frequency analyzing method using mother wavelets modified by scale numbers, was selected in this study for analyzing bileaflet valve closing sounds because it is easy to understand and has no limitations such as the cross-terms in the Wigner–Ville distribution or the tradeoff between time and frequency resolutions of the short-time Fourier transform. This study compares the properties of the mother wavelets of various CWTs and selects one that is suitable for detection of the clear split in bileaflet mechanical valve closing sound signals. This article also establishes a standard frequency analyzing system for bileaflet mechanical valve sounds. A preliminary study with chirp Doppler signals for comparing the frequency properties of the mother wavelets of various CWTs suggested that Ishikawas modified Morlet CWT has better time and frequency resolution at the highest frequency scale. Morlet/power CWT analysis of normal in vivo bileaflet valve closing sounds of the ST. Jude Medical (SJM), ATS, and Carbomedics (CM) valves demonstrated clear splits of very short interval at the highest level of frequency. Detection of the disappearance of the split by using this analytical method may be the key to identifying bileaflet mechanical valve malfunction in outpatient departments.

Wavelet analysis of valve closing sound detects malfunction of bileaflet mechanical valve

Several studies have reported the asynchronous closure of normal bileaflet valves (NBVs), resulting in a split in its closing sound; however, the clinical significance of this split has never been studied in malfunctioning bileaflet valves (MBVs). The study comprised 218 valves in 184 patients, including normal monoleaflet valves (n = 10), NBVs (n = 198), and MBVs (n = 10). Valve function was confirmed by cinefluoroscopy prior to analysis of the valve sound by the Morlet continuous wavelet transform (CWT). The split interval (SI) for each heartbeat was measured, and the coefficient of variation (CV) of its mean (valve SI) was calculated as a parameter for the fluctuation of the SI. The CWT of monoleaflet valves showed a single spike, whereas NBVs exhibited a clear split. There was no significant difference in valve SI between the aortic and mitral positions; however, the mean of the CV was significantly greater in the mitral position (n = 90, 0.507 ± 0.254) than in aortic position (n = 108, 0.353 ± 0.228, P = 0.000045). The split was not found in six (aortic; three, mitral; three) of ten patients with MBVs. The other four patients had a distinct split, but the CV was significantly lower for MBVs (0.138 ± 0.105) than for NBVs (0.343 ± 0.221, P = 0.042). Receiver-operating characteristics analysis demonstrated the cutoff line of the CV to be 0.112 for detecting malfunctioning aortic valves with the highest accuracy of 86.1%. This new system using the Morlet CWT can detect MBVs. It will be a useful modality for screening the function of bileaflet valves.

Measured Tube Technique for Ensuring the Correct Length of Slippery Artificial Chordae in Mitral Valvuloplasty

Mitral valvuloplasty using Gore-Tex (W.L. Gore & Associates, Inc, Flagstaff, AZ) as artificial chordae is often associated with difficulties in determining the length of the artificial chordae, as well as preventing knot slippage, especially for patients with broad anterior leaflet prolapse. We describe a simple technique that enables surgeons to easily determine the correct length of the artificial chordae and tie slippery knots without using a specific device.

Heparin reduction with the use of cardiotomy suction is associated with hyperfibrinolysis during distal aortic perfusion with a heparin-coated semi-closed cardiopulmonary bypass system

We sought to elucidate the effects of different anticoagulation levels and the use of cardiotomy suction on the postoperative coagulatory and fibrinolytic systems in patients undergoing distal aortic perfusion using a fully heparin-coated (semi-)closed cardiopulmonary bypass (CPB) system incorporating a soft reservoir bag. Thirty-two patients were divided into two groups: those who underwent cardiotomy suction (S group, 18 patients) and those who did not (N group, 14 patients). We administered 1–2 mg/kg heparin in the S group, which achieved an activated clotting time (ACT) of 345 ± 71 s. In the N group, we administered 0.7–1 mg/kg heparin, which achieved an ACT of 297 ± 52 s. Data on platelet counts and serum levels of fibrinogen, antithrombin III, D-dimer, and fibrin degradation products (FDP) were collected, and factors influencing these variables were analyzed by multiple regression analysis. Both the patient group and the initial ACT level were independent factors influencing postoperative levels of FDP and D-dimer, whereas peak ACT level and the use of selective visceral/renal shunt/perfusion, but not the patient group, were independent factors influencing the postoperative platelet counts. In the S group, a significant inverse correlation was found between the ACT and levels of FDP or D-dimer, whereas no correlation was found in the N group. The use of cardiotomy suction was associated with elevated FDP and D-dimer levels even when a fully heparin-coated semi-closed CPB system was used. Lower ACT levels with the use of cardiotomy suction were associated with higher FDP and D-dimer levels, whereas such a relationship did not exist when cardiotomy suction was not used.

New automated wavelet analytical system with a cellular phone for recording intercellular phone remote transmitted bileaflet valve sound.

The wavelet analytical system developed in our institute can detect a malfunctioning bileaflet valve by analyzing the split interval (SI) of bileaflet valve sound (BLVS) caused by asynchronous closure of both leaflets. However, this system is limited in its clinical application because of the complications of both valve sound recording and analytical protocols. This study established a new system that improved upon these limitations, and evaluated its clinical efficiency and the possibility of intercellular phone remote transmission of BLVS (ICTB). Fifty-one valves in 36 patients with St. Jude Medical bileaflet valve replacement were examined by fluoroscopy, 90 BLVS files (42 mitral and 48 aortic valve files) were recorded, and 1720 individual BLVS recordings in these files were analyzed with the new system. The new system consists of a cellular phone for BLVS recording and an automated algorithm for analysis with the Morlet continuous wavelet transform. ICTB was also investigated clinically. The new system showed great improvement over the original system by simplifying BLVS recording and reducing analysis time by approximately 65%. This system detected two malfunctioning valves with coefficients of variation (CV) for SI below 0.112, a previously proposed criterion for malfunction. ICTB also proved to be a useful BLVS recording method for determining SI. The new system described in this study could eliminate the factors limiting clinical application of the old system, and ICTB was found to be a clinically applicable BLVS recording method.

Surgery for Left Ventricular Outflow Tract Obstruction with a Relatively Thin Interventricular Septum

Abstract Background To examine the results of myectomy and mitral valve surgery for systolic anterior motion (SAM) of the mitral valve and left ventricular outflow tract obstruction (LVOTO) with a relatively thin interventricular septum. Methods The subjects were 12 patients with SAM and LVOTO. Eight had hypertrophic obstructive cardiomyopathy (HOCM) with a mean interventricular septal thickness of 16 mm. Three had sigmoid septum and one had an unknown etiology. For HOCM, isolated extended myectomy was performed when mitral regurgitation was mild (n = 1) and extended myectomy plus mitral valve surgery was performed when mitral regurgitation was more than mild (n = 4) or primary valve etiologies existed (n = 3). Myectomy was performed for the three cases with sigmoid septum. Myectomy plus height reduction of the posterior mitral leaflet was performed for the one case with the unknown etiology of SAM. Results In the patients with HOCM, the maximum LVOT pressure gradient significantly decreased from 140 ± 18 to 16 ± 6 and 3 ± 3 mm Hg, while mitral regurgitation significantly decreased from 2.3 ± 0.5 to 0.5 ± 0.3 and 0.4 ± 0.2 at pre‐op, early post‐op, and last follow‐up (3 ± 1 years), respectively. In the other etiologies, the maximum LVOT pressure gradient changed from 56 ± 15 to 25 ± 15 and 5 ± 4 mm Hg; mitral regurgitation changed from 2.0 ± 0.6 to 1.3 ± 0.3 and 1.3 ± 0.8, at pre‐op, early post‐op, and the last follow‐up (3 ± 2 years), respectively. Conclusion Myectomy with mitral valve surgery is an option for SAM and LVOTO in patients with a relatively thin interventricular septum.

Can we change the operative criteria for the MAZE procedure combined with valve surgery in the era of radiofrequency devices

PurposeAfter radiofrequency (RF) ablation became available, the indication of MAZE procedure conducted with bipolar RF was expanded. We examined the efficacy and feasibility of the RF MAZE procedure in valve surgery and identified the predictors of atrial fibrillation (AF) recurrence.MethodsForty-four patients had permanent AF at the time of operation and underwent a biatrial RF MAZE procedure. Univariate and multivariate analysis for the predictor of permanent AF recurrence and follow-up studies were performed.ResultsOf the patients, 37 (84.1%) were in non-AF rhythm at discharge and 25 (80.6%) were at the latest follow-up (mean, 2.1 ± 1.2 years). In stepwise multivariate analysis, left atrial dimension (LAD) > 61.5 mm was an independent predictor of early-term recurrence of AF (P = 0.006) and late-term recurrence (P = 0.038) as well. F-wave voltage <0.1 mV was significant in univariate analysis but was not significant in multivariate analysis for predictor of late-term AF recurrence. Avoidance of AF in the late term was 56% for LAD > 60 mm whereas it was 91% for LAD ≤ 60 mm (P = 0.043), 67% for F-wave < 0.1 mV compared to 100% for F-wave ≥ 0.1 mV (P = 0.031), and 43% for LAD > 60 mm and F-wave < 0.1 mV compared to 91% for LAD ≤ 60 mm and/or F-wave ≥ 0.1 mV (P = 0.016), respectively. Although avoidance of AF in the late term was lower in patients with LAD > 60 mm or F-wave < 0.1 mV, more than half of these patients were free from AF in the late term.ConclusionLA size was assumed to be a simple and strong predictor of recurrent AF in this procedure. Predictive criteria that had been widely employed for the “cut-and-sew” MAZE procedure accompanied with valve surgery can be expanded in the MAZE procedure with RF devices.

Proximal Aortic Replacement with Ascending-Descending Bypass for a Diffuse Aneurysm : Report of a Case

We performed successful ascending-arch aortic replacement and concomitant ascending-to-descending aorta bypass with exclusion of a descending thoracic aneurysm, via median sternotomy, for a ruptured aortic aneurysm involving the entire thoracic aorta. The patient was an 80-year-old man with cardiopulmonary dysfunction and a history of lung tuberculosis. This operation, which has been used for complex descending thoracic aortic lesions such as recoarctation, is a feasible option for a diffuse thoracic aortic aneurysm when single-stage repair is mandatory.

The scalographic pattern of Morlet continuous wavelet transform can differentiate bileaflet valve function

The authors have discussed the significance of the Morlet continuous wavelet transform of bileaflet mechanical heart valve (BLMHV) sound for detecting its malfunction: consecutive single patterns on the scalogram alway suggested its malfunction, whereas the tandem pattern with two steepled figures was demonstrated in both normal and malfunctioning valves. Therefore, authors have tried to distinguish this pattern between them by manually calculated multiple scalographic parameters. Although only the sum of wavelet coefficients (SWC) is supposed to be closer to valve sound property than other parameters, its calculation was not available in the original wavelet application. Therefore, the application was customized in the current study to semi-automatically calculate the SWC ratio between two figures for classifying the scalographic pattern of malfunctioning valves, and its efficacy to distinguish valve function was compared to other parameters. Among 155 BLMHVs, 6 valves with consecutive single patterns (type-I) and other 6 with two similar needle-like narrow figures (type-II) were confirmed to be a malfunction by fluoroscopic examination, whereas 14 malfunctioning valves with the tandem pattern which showed a great difference between two figure sizes (type-III) were distinguished from 129 normal valves by the cutoff point of the SWC ratio < 0.482 with the highest AUC (0.960) compared to other parameters by the ROC analysis.