Nobuaki Hirata

Quantitative Ultrasonic Tissue Characterization Can Identify High-Risk Atherosclerotic Alteration in Human Carotid Arteries

BACKGROUND Recently, ultrasonic tissue characterization of the composition of plaques has been performed in a quantitative fashion on the basis of integrated backscatter (IBS) analysis, but most of those studies have used high-frequency ultrasound to obtain microscopic images. METHODS AND RESULTS We performed B-mode measurement and IBS signal analysis with acoustic densitometry with a 7.5-MHz linear-array transducer in freshly excised human aortas (n=58) (normal, atheromatous, and fibrous tissue) obtained at autopsy. Atheromatous and fibrous tissue had a similar intima-media thickness (IMT), but the IBS value in atheromatous specimens was lower than that in fibrous specimens. We further applied this method to human carotid ultrasonography. The subjects were young (80 regions), middle aged with 1 or no coronary risk factors (low risk) (120 regions), middle aged with >/=2 coronary risk factors (high risk) (240 regions), or elderly (80 regions) or were patients with myocardial infarction (MI) with multivessel disease (90 regions). The IMT was similar in middle-aged, elderly, and MI subjects. In contrast, the IBS value was significantly higher in elderly subjects and lower in high-risk middle-aged and MI subjects compared with that in low-risk middle-aged subjects. The percent of regions diagnosed as atheromatous (IBS less than mean minus 2-SD value of IBS in young subjects) was 11% in low-risk middle-aged subjects, 29% in high-risk middle-aged subjects, and 63% in the MI group. CONCLUSIONS In conjunction with conventional B-mode imaging, IBS analysis with carotid ultrasonography appeared to provide prognostic information to identify a high-risk group with systemic atherosclerosis, which could lead to coronary heart disease in individuals with early-stage disease.

The long-term outcome of a surgical repair of sinus of valsalva aneurysm.

BACKGROUND In order to clarify the long-term outcome after surgical repair of a sinus of Valsalva aneurysm, we retrospectively assessed the operative results for patients treated in our institute. METHODS The subjects were 27 patients who had undergone an operation between 1958 and 1996. For associated aortic regurgitation (AR) aortic valve repair was performed in 13 patients, 12 of whom had a ventricular septal defect (VSD); and an aortic valve replacement was performed in 3 patients, 1 of whom had a VSD. RESULTS Five of the 13 patients who had aortic valve repair needed aortic valve replacement because AR developed after a period of between 7 and 13 years; those cases were complicated by VSD. Another 2 patients with mild AR also complicated by VSD are currently under observation. CONCLUSIONS Although the postoperative outcome of the aortic valve repairs was good, cases that were complicated by VSD plus associated AR tended to develop AR later after surgery. Therefore, careful observation of the postoperative course is necessary.

Predictive value of preoperative serum cholinesterase concentration in patients with liver dysfunction undergoing cardiac surgery.

AbstractObjective There are an increasing number of patients with severe liver dysfunction subjected to open heart surgery. This retrospective study was designed to assess operative results and clarify the degree of liver injury in patients with liver dysfunction undergoing open heart surgery. In addition, determinants influencing their prognosis were assessed. Methods In a 9‐year period from 1988 to 1996, we operated on 31 patients with posthepatitis liver dysfunction and 16 with chronic passive congestion of the liver. This group was 2.3% and 1.6% of the 1368 patients undergoing cardiac surgery in the same period. We compared several perioperative factors between survivors and nonsurvivors to determine risk factors affecting mortality. Results In the group with posthepatitis liver dysfunction, the postoperative course of 5 patients among 31 (16.1%) was poor. Serum cholinesterase concentration was lower only in the nonsurvivor group (nonsurvivor vs survivor: 1979 ± 949 vs 3515 ± 1424 lU/l, p < 0.05). All patients with cholinesterase < 2000 IU/L died. The duration of CPB (212 ± 53 vs 150 ± 54 minutes, p < 0.03) and ACC time (151 ± 38 vs 96 2 40 minutes, p < 0.02) was longer in the nonsurvivor group. In the group with chronic passive congestion, the postoperative course of 5 of 16 (31.3%) patients with valvular disease was poor. Serum cholinesterase concentration was lower only in the nonsurvivor group (nonsurvivor vs survivors: 2006 ± 435 vs 3483 ± 1442 IU/L, p < 0.021, and all patients with cholinesterase < 2000 IU/L died. Postoperative bleeding was greater in the nonsurvivor group (3327 ± 2106 vs 1428 ± 643 mL, p < 0.05). Multivariate logistic regression analysis including the described pre‐ and intraoperative factors identified only serum cholinesterase concentration (F = 9.18) as significant. Conclusions A low value of preoperative serum cholinesterase (< 2,000 IU/L) is thought to be the predictor of prognosis after open heart surgery in patients with severe posthepatitis and congestive liver dysfunction. operative factors (cardiopulmonary time in posthepatitis liver dysfunction and postoperative bleeding in the congestive liver dysfunction) also influenced the prognosis.

New strategy for treatment of MRSA mediastinitis: one-stage procedure for omental transposition and closed irrigation

Mediastinitis due to methicillin-resistant Staphylococcus aureus is a devastating potential complication of cardiac surgery. We treated 4 patients with this condition using a new technique. First we performed an early radical removal of infected tissue and omental transposition with direct primary closure of the sternum and closed continuous irrigation with saline/vancomycin hydrochloride; that was followed by an administration of intravenous antibiotics. We obtained good clinical results, which are reported herein along with the clinical courses.

The freestyle stentless bioprosthesis for prosthetic valve endocarditis

We report a case of methicillin-resistant Staphylococcus aureus-induced prosthetic valve endocarditis, which was successfully treated with aortic valve replacement using the Freestyle stentless bioprosthesis. The total root and stentless design of this bioprosthesis allows for more radical removal of infected tissue and easier treatment for annular abscess, while requiring less prosthetic materials than a conventional prosthesis. This bioprosthesis thus seems to be a valuable option for active endocarditis.

Assessment of myocardial distribution of retrograde and antegrade cardioplegic solution in the same patients.

OBJECTIVE In order to clarify intramyocardial delivery and distribution of retrograde cardioplegic solution in humans, we induced both ante- and retrograde methods in the same patients to compare their respective delivery and distribution using myocardial contrast echocardiography during surgery. METHODS 15 patients consisting of nine patients with valvular heart diseases and six patients with coronary artery diseases (including two patients with myocardial infarcted areas and two patients with areas supplied by coronary collateral situation associated with totally occluded coronary arteries without myocardial infarction). Induction of cardioplegia was initially accomplished antegradely and thereafter retrogradely. RESULTS In valvular heart disease, retrograde cardioplegic solution was distributed less homogeneously, and was not delivered to the midportion of the interventricular septum in two-thirds of the patients (6/9). The transmural myocardial distribution in the anterior, lateral, and posterior walls in the left ventricle were similar for both ante- and retrograde cardioplegic solution, while delivery to the endocardial halves was better than to the epicardial halves (endo-/epicardial intensity ration in antegrade versus retrograde: 1.31 +/- 0.24 versus 1.29 +/- 0.26; 1.19 +/- 0.05 versus 1.36 +/- 0.23; 1.33 +/- 0.28 versus 1.44 +/- 0.35, respectively (all NS)). For delivery to the right ventricle, the existence of small cardiac vein was important. In patients with small cardiac vein (34% in our study), the delivery to the right ventricular dorsal walls was shown. In coronary heart disease, retrograde cardioplegic solution was well delivered to the areas by coronary collateral situation associated with totally occluded coronary arteries, but antegrade solution was not. Neither ante- nor retro grade solution was delivered to myocardial infarcted areas. CONCLUSIONS These results have important implications for planning strategies for myocardial protection. We think that it is necessary to fully grasp the coronary arterial and venous anatomy of individual patients and to know how to use either ante- or retrograde cardioplegia properly.

Pulmonary blood flow distribution after the total cavopulmonary connection for complex cardiac anomalies.

SummaryIn total cavopulmonary connection (TCPC), the anastomotic portion of the caval veins to the pulmonary artery (PA) is decided empirically based on personal experience. To compare the pulmonary flow distribution from both caval veins in various types of cavopulmonary anastomosis, intrapulmonary ventilation-perfusion distribution after TCPC was studied using lung scanning. We studied 11 patients, 2 to 37 years old, at 30–84 months after TCPC. Lung scanning was performed by administering 185 MBq of xenon-133 saline solution from their upper extremities and, after xenon-133 was washed out, from their lower extremities. Radionuclide counts on both lungs were obtained and intrapulmonary ventilation-perfusion distribution was assessed. In 4 patients whose superior vena cava (SVC)-PA anastomosis was on the right side of the inferior vena cava (IVC)-PA anastomosis, the blood flow distribution of the right and left lungs was 57.4%: 42.6%. In 3 patients whose SVC-PA anastomosis was on the left side of the IVC-PA anastomosis, the blood flow distribution of the right and left lungs was equal in both lungs (right, 53.1%; left, 46.9%). Systemic arterial oxygen saturation increased after TCPC (before TCPC, 85.3% ± 2.7% and after TCPC, 89.8% ± 2.3% (P < 0.05) in group R; before TCPC, 86.1% ± 2.8% and after TCPC, 93.6% ± 0.6% (P < 0.02) in group L). After TCPC, the value in group L had a tendency to be greater than that in group R (P < 0.04), in spite of the same values of systemic arterial oxygen saturation before TCPC and cardiac index (group R, 2.9 ± 0.96; group L, 3.4 ± 0.37). Lung scanning with xenon-133 revealed the distribution of pulmonary blood flow in the patients after TCPC quantitatively, and in the patients whose SVC-PA anastomosis was on the left side of the IVC-PA anastomosis, the right and left balance of the pulmonary blood flow distribution appeared to be more balanced compared with patients whose connection was done the opposite way.

Is median sternotomy invasive? A comparison between minimally invasive direct coronary artery bypass and off-pump bypass

Although minimally invasive direct coronary artery bypass (MIDCAB) eliminates the need for median sternotomy and cardiopulmonary bypass, its indications are limited. Conversely, coronary artery bypass without cardiopulmonary bypass (off-pump bypass) enables complete surgical revascularization under an optimal surgical field established by median sternotomy, even if patients have multivessel disease. The present study was designed to determine the invasiveness of median sternotomy by comparing 11 patients who underwent MIDCAB and 5 who underwent off-pump bypass between May 1997 and April 1998. There were no significant differences between the MIDCAB group and the off-pump group in age, being 57 ± 11vs 66 ± 8 years old, the operative time, being 321 ± 149vs 441 ± 205 min, the number of grafts, being 1.0vs 1.4/patient, peak creatine kinase (CK) values, being 662 ± 436vs 609 ± 56 IU/l, the peak CK-muscle-brain values, being 12 ± 9vs 16 ± 5 IU/l, and the postoperative blood loss, being 369 ± 198vs 541 ± 204 ml. Although there was no significant difference in peak C-reactive protein, at 17 ± 5vs 20 ± 2 mg/dl, the periods declining within the normal ranges were shorter in the MIDCAB group than in the offpump group, at 7 ± 1 vs 15 ± 2 days (P>0.01). The hospital stay was almost the same in both groups, at 16 ± 8vs 26 ± 14 days. These findings suggest that off-pump bypass is more invasive than MIDCAB, which may be attributed to the median sternotomy.

Noninvasive evaluation of internal thoracic artery and left anterior descending coronary artery anastomotic sites using transthoracic Doppler echocardiography: comparison with coronary arteriography.

OBJECTIVES This study was designed to evaluate anastomotic sites located between the internal thoracic artery and left anterior descending coronary artery using transthoracic Doppler echocardiography, and then to clarify the accuracy of those results by comparison with coronary arteriographic findings. METHODS We examined 35 consecutive patients who had undergone bypass surgery. The echocardiographic examinations were performed within approximately 1 week of follow-up coronary arteriography, which occurred at 4.3 +/- 2.2 months after bypass surgery. We measured the diameter using intraluminal flow signals, and we also measured flow velocity. RESULTS Adequate spectral Doppler recordings of coronary flow in the anastomosis were obtained in 31 (89%) of the 35 study patients. In the normal anastomosis group (n = 25), the diameter and the peak blood flow velocity of the internal thoracic artery and left anterior descending coronary artery were 1.5 +/- 0.3 mm and 2.0 +/- 0.4 mm, and 58 +/- 25 cm/s and 47 +/- 20 cm/s, respectively. Stringed internal thoracic artery was found in 4 patients; the echocardiographic findings revealed a greater amount of information regarding the physiologic state in the area of anastomosis compared with angiographic findings. In a stenotic anastomosis found in 2 patients, the blood flow velocity findings at the anastomotic sites (83 +/- 228 cm/s) were higher than those in normal anastomotic patients (59 +/- 28 cm/s). CONCLUSIONS Transthoracic Doppler echocardiography enabled an effective evaluation of anastomotic sites between the internal thoracic artery and left anterior descending coronary artery in over 80% of our patients. This totally noninvasive method is thought to be reliable and able to provide a greater amount of information, compared with coronary arteriography, regarding the physiologic state of an anastomosis, such as a competitive relationship.

Changes in left anterior descending coronary artery flow profiles after coronary artery bypass grafting examined by means of transthoracic Doppler echocardiography

OBJECTIVE We sought to investigate the changes of velocity profiles in the left anterior descending coronary artery after coronary artery bypass grafting using transthoracic Doppler echocardiography. METHODS Forty-five patients who received a bypass graft to the left anterior descending coronary artery were studied. Before coronary artery bypass grafting, Doppler velocity profiles of the distal left anterior descending coronary artery were recorded with transthoracic Doppler echocardiography. Peak systolic velocity, mean systolic velocity, peak diastolic velocity, mean diastolic velocity, total velocity time integral, systolic velocity time integral, and diastolic velocity time integral were measured. Three weeks after coronary artery bypass grafting, left anterior descending coronary artery antegrade flow in the distal portion of the anastomosis was obtained by using the same method. Coronary angiography was performed before and 3 weeks after coronary artery bypass grafting. RESULTS The overall success rate of measuring the left anterior descending coronary artery flow was 60.0% preoperatively and 80.0% postoperatively. In 25 patients, in whom all parameters were obtained both before and after coronary artery bypass grafting, the following increased significantly after coronary artery bypass grafting: peak systolic velocity (14.86 +/- 7.50 vs 25.07 +/- 17.02 cm/s, P =.0045), mean systolic velocity (9.86 +/- 5.42 vs 18.03 +/- 12.94 cm/s, P =.0026), peak diastolic velocity (24.26 +/- 12.54 vs 48.28 +/- 31.66 cm/s, P =.0021), mean diastolic velocity (14.94 +/- 6.65 vs 30.36 +/- 20.71 cm/s, P =.0022), diastolic velocity time integral (7.22 +/- 2.88 vs 15.55 +/- 10.39 cm, P =.0009), total velocity time integral (10.50 +/- 4.48 vs 19.27 +/- 12.63 cm, P =.0034), and diastolic-to-systolic velocity time integral ratio (3.09 +/- 1.53 vs 4.97 +/- 2.75, P =.0044). Angiography showed graft patency and no significant change in left anterior descending coronary artery stenosis in all patients. CONCLUSIONS Transthoracic Doppler echocardiography showed a significant increase in some parameters in left anterior descending coronary artery flow after coronary artery bypass grafting. Measurement of left anterior descending coronary artery flow by means of transthoracic Doppler echocardiography might be a noninvasive method to evaluate the effect of bypass grafting on the left anterior descending coronary artery.