Successful Catheter Ablation for Paroxysmal Supraventricular Tachycardia with Two Alternating Cycle Lengths

A 62-year-old male was transferred to our hospital complaining of palpitations. His heart rate was 185/min. Electrocardiogram showed a narrow QRS regular tachycardia and the tachycardia changed spontaneously to another narrow QRS tachycardia with two alternating cycle lengths. The arrhythmia was stopped by the administration of adenosine triphosphate. Findings from electrophysiological study suggested that there was an accessory pathway (AP) and dual atrioventricular (AV) nodal pathways. After AP ablation, any other tachyarrythmias were not induced. We supposed that the tachycardia was paroxysmal supraventricular tachycardia involving AP and anterograde conduction alternating between slow and fast AV nodal pathways.

Successful left ventricular lead placement by way of an azygos vein for a patient performing cardiac resynchronization therapy implantation with an occluded left subclavian vein: A case report

Central venous obstruction following pacemaker implantation is not uncommon and can prove challenging in the case of a system upgrade to a cardiac resynchronization therapy pacemaker (CRT-P). We describe the case of a patient who underwent a successful upgrading procedure of a pacemaker to a CRT-P in the presence of an occluded left subclavian vein and superior vena cava, using collateral veins that drained into right atrium.

Machine Learning for Prediction of Technical Results of Percutaneous Coronary Intervention for Chronic Total Occlusion

(1) Background: The probability of technical success in percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) represents essential information for specifying the priority of PCI for treatment selection in patients with CTO. However, the predictabilities of existing scores based on conventional regression analysis remain modest, leaving room for improvements in model discrimination. Recently, machine learning (ML) techniques have emerged as highly effective methods for prediction and decision-making in various disciplines. We therefore investigated the predictability of ML models for technical results of CTO-PCI and compared their performances to the results from existing scores, including J-CTO, CL, and CASTLE scores. (2) Methods: This analysis used data from the Japanese CTO-PCI expert registry, which enrolled 8760 consecutive patients undergoing CTO-PCI. The performance of prediction models was assessed using the area under the receiver operating curve (ROC-AUC). (3) Results: Technical success was achieved in 7990 procedures, accounting for an overall success rate of 91.2%. The best ML model, extreme gradient boosting (XGBoost), outperformed the conventional prediction scores with ROC-AUC (XGBoost 0.760 [95% confidence interval {CI}: 0.740-0.780] vs. J-CTO 0.697 [95%CI: 0.675-0.719], CL 0.662 [95%CI: 0.639-0.684], CASTLE 0.659 [95%CI: 0.636-0.681]; p < 0.005 for all). The XGBoost model demonstrated acceptable concordance between the observed and predicted probabilities of CTO-PCI failure. Calcification was the leading predictor. (4) Conclusions: ML techniques provide accurate, specific information regarding the likelihood of success in CTO-PCI, which would help select the best treatment for individual patients with CTO.

Impact of the Temporal Distribution of Coronary Artery Disease Progression on Subsequent Consequences in Patients with Acute Coronary Syndrome

The late consequences of acute coronary syndrome (ACS) have been underestimated. We hypothesized that the temporal distribution of the clinically silent coronary artery disease progression (CP) is associated with the subsequent consequences of ACS.We studied 243 patients (202 men, 64 ± 10 years) with ACS undergoing percutaneous coronary intervention (PCI) during initial hospitalization. All patients underwent serial coronary angiograms (CAGs) immediately before PCI and at 7 ± 3 and 60 ± 10 months after presentation. CP was defined as an increase ≥ 15% in stenosis severity of the lesion between 2 serial CAGs. The impact of CP between each 2 serial CAGs on subsequent major adverse cardiovascular and cerebrovascular events (MACCEs) after the final CAG was examined using multivariate Cox and propensity-matched analyses.During the median follow-up duration after the final CAG of 67 months, 76 MACCEs (31.3%) were observed. Multivariate Cox proportional hazards analysis revealed that CP between the first and second CAGs (hazard ratio [HR], 2.28; 95% confidence interval [CI], 1.32-3.94; P = 0.003) and CP between the second and final CAGs (HR, 1.96; 95% CI, 1.20-3.21; P = 0.008) were independently associated with a higher rate of MACCEs beyond the final CAG. Consistent results were obtained in the propensity score-matched analyses.CP in both the early (0-7 months) and late phases (7-60 months) were independently associated with subsequent clinical events. This may indicate the prognostic significance of persistent widespread coronary disease activity following presentation in patients with ACS undergoing PCI.

Distinction Between Precapillary and Postcapillary Pulmonary Hypertension by the Atrial Volume Ratio on Transthoracic Echocardiography

OBJECTIVES

The differential diagnosis between precapillary and postcapillary pulmonary hypertension (PH) is important for deciding on the appropriate therapeutic strategy. The aim of this study was to assess whether the atrial volume ratio can differentiate precapillary and post-capillary PH.

METHODS

Seventy-seven patients with PH who underwent transthoracic echocardiography (TTE) and right heart catheterization were retrospectively studied. Pulmonary hypertension was defined as a mean pulmonary arterial pressure of 25 mm Hg or higher by right heart catheterization. Patients with a pulmonary capillary wedge pressure higher than 15 mm Hg were classified as having postcapillary PH, and patients with a pulmonary capillary wedge pressure of 15 mm Hg or lower were classified as having precapillary PH. The atrial volume ratio derived from TTE was defined as right atrial volume divided by left atrial volume.

RESULTS

Forty-four (57%) of 77 patients had precapillary PH by the right heart catheterization classification. The atrial volume ratio was significantly higher in precapillary PH than in postcapillary PH (1.03 ± 0.69 versus 0.50 ± 0.19; P < .001). The area under the receiver operating characteristic curve of the atrial volume ratio for detecting postcapillary PH was 0.84 (95% confidence interval: 0.75-0.93). Adding the atrial volume ratio to the left ventricular ejection fraction yielded a high area under the curve of 0.90 (95% confidence interval, 0.83-0.96) for distinguishing precapillary and postcapillary PH.

CONCLUSIONS

The atrial volume ratio assessed by TTE might be useful for differential diagnosis between precapillary and postcapillary PH.

Impact of Hemodialysis on Procedural Outcomes of Percutaneous Coronary Intervention for Chronic Total Occlusion: Insights From the Japanese Multicenter Registry

Background

Among patients treated with percutaneous coronary intervention for chronic total occlusion (CTO‐PCI), patients on long‐term hemodialysis are at significantly high risk for cardiovascular mortality and morbidity. However, clinical or angiographic predictors that might aid in better patient selection remain unclear. We aimed to assess the acute impact of hemodialysis in patients who underwent CTO‐PCI.

Methods and Results

The Retrograde Summit registry is a multicenter, prospective registry of patients undergoing CTO‐PCI at 65 Japanese centers. Patient characteristics and procedural outcomes of 4749 patients were analyzed, according to the presence (n=313) or absence (n=4436) of baseline hemodialysis. A prediction model for technical failure among hemodialysis patients was also developed. The technical success rate of CTO‐PCI was significantly lower in hemodialysis than in nonhemodialysis patients (78.0% versus 89.1%, P<0.001). The rates of in‐hospital major adverse cardiac and cerebrovascular events were similar between the 2 groups (1.6% versus 0.9%, P=0.24). Irrespective of clinical/angiographic characteristics or previously developed scoring systems, hemodialysis independently predicted technical failure for CTO‐PCI. Among hemodialysis patients, predictors of technical failure were blunt stump (odds ratio 2.45, 95% confidence interval, 1.15–5.21, P=0.021), severe lesion calcification (odds ratio 2.50, 95% confidence interval, 1.19–5.24, P=0.015), and absence of diabetes mellitus (odds ratio 3.15, 95% confidence interval, 1.49–6.64, P=0.003). In hemodialysis patients without these predictors, the technical success rate was 96.2%.

Conclusions

Hemodialysis is significantly associated with technical failure. Contemporary CTO‐PCI seems feasible and safe in selected hemodialysis patients.

ST-segment category at acute presentation is associated with the time course of coronary artery disease progression in patients with acute coronary syndromes

BACKGROUND

Several studies have shown higher early mortality for ST-segment elevation acute coronary syndrome (STEACS), but late mortality remains consistently higher for non-ST-segment elevation acute coronary syndrome (NSTEACS). We hypothesized that ST-segment category at acute presentation is associated with the time course of coronary artery disease progression (CP) of nonculprit lesions in patients with acute coronary syndrome (ACS).

METHODS

A total of 226 patients (182 men, age 65 ± 10 years) with STEACS (n = 95) or NSTEACS (n = 131) who underwent percutaneous coronary intervention (PCI) during initial hospitalization were studied. All patients underwent serial coronary angiograms (CAGs) performed immediately before PCI and at 7 ± 3 months and 60 ± 10 months after presentation. CP was defined as an increase in stenosis severity >15% of a nonculprit lesion between 2 serial CAGs.

RESULTS

The rate of CP between the first and second CAGs did not differ by ST-segment category at acute presentation. Compared to STEACS, NSTEACS had a higher rate of CP between the second and final CAGs (27.4 vs. 42.7%, P = 0.018). Multivariate analysis showed that the independent predictors of CP between the second and final CAGs were NSTEACS (odds ratio 2.709, P = 0.003), estimated glomerular filtration rate <60 ml/min/1.73 m² (odds ratio 2.447, P = 0.015), and diabetes mellitus (odds ratio 2.135, P = 0.021).

CONCLUSIONS

Irrespective of conventional risk factors and angiographic findings, ST-segment category at initial presentation is associated with the persistency of widespread coronary disease activity following presentation in ACS patients undergoing PCI. This may partly explain the time-dependent differences in outcomes of patients with STEACS and NSTEACS.

Higher CHADS2 score is associated with impaired coronary flow reserve: A study using phase contrast cine magnetic resonance imaging

BACKGROUND

The presence of coronary microvascular dysfunction (CMD) is an important prognostic marker for coronary artery disease (CAD) patients. The purpose of this study was to investigate whether the CHADS2 score is associated with CMD evaluated by magnetic resonance imaging (MRI).

MATERIALS AND METHODS

One hundred forty three patients with known or suspected CAD (mean age 70.3±9.5years) were enrolled. All patients did not have any significant coronary stenosis on X-ray coronary angiography (CAG) at the time of MRI acquisition. By using a 1.5T MRI scanner, breath-hold phase contrast cine MRI images of coronary sinus (CS) were obtained to assess the blood flow of CS both at rest and during adenosine triphosphate (ATP) infusion. Coronary flow reserve (CFR) was calculated as CS blood flow during ATP infusion divided by CS blood flow at rest. CMD was defined as CFR<2.5 according to a previous study. Patients were allocated to four groups based on the CHADS2 score (group1: CHADS2 score=0, group2: CHADS2 score=1; group3: CHADS2 score=2, and group4: CHADS2 score≥3).

RESULTS

Mean CFR was 2.81±0.95 (77.6±32.7mL/min at rest; 208.2±86.5mL/min during ATP infusion, p<0.001). Patients with higher CHAD2 score had lower CFR. In the multiple logistic regression analysis, CHADS2 score was independently associated with CFR (odds ratio=0.61, 95% confidence interval: 0.37-0.99, p=0.049).

CONCLUSIONS

Higher CHADS2 score was significantly associated with lower CFR evaluated by phase contrast cine MRI.

Impairment of Coronary Flow Reserve Evaluated by Phase Contrast Cine-Magnetic Resonance Imaging in Patients With Heart Failure With Preserved Ejection Fraction

BACKGROUND

Phase contrast (PC) cine-magnetic resonance imaging (MRI) of the coronary sinus allows for noninvasive evaluation of coronary flow reserve (CFR), which is an index of left ventricular microvascular function. The objective of this study was to investigate coronary flow reserve in patients with heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

We studied 25 patients with HFpEF (mean and SD of age: 73±7 years), 13 with hypertensive left ventricular hypertrophy (LVH) (67±10 years), and 18 controls (65±15 years). Breath-hold PC cine-MRI images of the coronary sinus were obtained to assess blood flow at rest and during ATP infusion. CFR was calculated as coronary sinus blood flow during ATP infusion divided by coronary sinus blood flow at rest. Impairment of CFR was defined as CFR <2.5 according to a previous study. The majority (76%) of HFpEF patients had decreased CFR. CFR was significantly decreased in HFpEF patients in comparison to hypertensive LVH patients and control subjects (CFR: 2.21±0.55 in HFpEF vs 3.05±0.74 in hypertensive LVH, 3.83±0.73 in controls; P<0.001 by 1-way ANOVA). According to multivariable linear regression analysis, CFR independently and significantly correlated with serum brain natriuretic peptide level (β=-68.0; 95% CI, -116.2 to -19.7; P=0.007).

CONCLUSIONS

CFR was significantly lower in patients with HFpEF than in hypertensive LVH patients and controls. These results indicated that impairment of CFR might be a pathophysiological factor for HFpEF and might be related to HFpEF disease severity.

Glycemic Variability on Continuous Glucose Monitoring System Predicts Rapid Progression of Non-Culprit Lesions in Patients With Acute Coronary Syndrome

BACKGROUND

Although rapid progression (RP) of coronary artery disease (CAD) has been shown to be a powerful predictor of cardiovascular events, predictors of RP are not fully understood in patients with acute coronary syndrome (ACS).

METHODS AND RESULTS

We prospectively investigated the clinical impact of glycemic variability (GV), as determined on continuous glucose monitoring system (CGMS), on RP of non-culprit lesions in 88 patients with ACS. RP was defined as ≥10% diameter reduction in a pre-existing stenosis ≥50%; ≥30% diameter reduction in a stenosis <50%; development of a new stenosis ≥30% in a previously normal segment; or progression of any stenosis to total occlusion. Patients were classified into 2 groups according to the presence (progressor, n=20) or absence (non-progressor, n=68) of RP. All patients were equipped with a CGMS during the stable phase, and mean amplitude of glycemic excursion (MAGE) was calculated as a marker of GV. Mean MAGE was significantly higher in progressors than in non-progressors (55±19 mg/dl vs. 37±18 mg/dl, P<0.01). On multiple logistic regression analysis, MAGE was an independent predictor of RP (odds ratio, 1.06 per 1 mg/dl; P<0.01).

CONCLUSIONS

MAGE early after the onset of ACS is a predictor of RP of non-culprit lesions.

Prognostic significance of quantitative assessment of focal myocardial fibrosis in patients with heart failure with preserved ejection fraction

BACKGROUND

The aim of this study was to investigate the prognostic value of myocardial focal fibrosis quantified by late gadolinium enhanced (LGE) magnetic resonance imaging (MRI) in patients with heart failure with preserved ejection fraction (HFpEF).

METHODS

One-hundred eleven HFpEF patients (mean age: 70 ± 14 years, 55 (50%) female) were enrolled. We excluded patients with previous history of coronary artery disease and/or ischemic pattern of hyper enhancement on LGE MRI. Myocardial enhancement was defined using signal intensity >2SD above the mean signal intensity of a remote myocardium. Major adverse cardiovascular events were defined as cardiovascular death and heart failure requiring hospitalization.

RESULTS

During a mean follow up period of 851 ± 609 days, 10 events (2 cardiovascular death, 8 hospitalization for heart failure decompensation) were observed. Area under the receiver operating characteristics curve of LGE% for the detection of future events was 0.721 (95% CI: 0.628-0.802). Multivariate Cox proportional hazard analysis showed that LGE% is an independent predictor of future events after the adjustment with prognostic 5 factors - age, diabetes mellitus, New York Heart Association classification, history of heart failure hospitalization and left ventricular ejection fraction - which were identified in the I-PRESERVE study (Irbesartan in Heart Failure with Preserved Ejection Fraction Study) (hazard ratio=7.913, 95% CI: 1.603-39.05, P=0.012).

CONCLUSIONS

Larger size of LGE was significantly associated with high rate of future cardiovascular death and heart failure hospitalization, suggesting that the quantification of myocardial focal fibrosis by LGE MRI could be useful for the risk stratification in HFpEF patients.

Prognostic value of cardiovascular magnetic resonance derived right ventricular function in patients with interstitial lung disease

BACKGROUND

Cardiovascular magnetic resonance (CMR) provides non-invasive and more accurate assessment of right ventricular (RV) function in comparison to echocardiography. Recent study demonstrated that assessment of RV function by echocardiography was an independent predictor for mortality in patients with interstitial lung disease (ILD). The purpose of this study was to determine the prognostic significance of CMR derived RV ejection fraction (RVEF) in ILD patients.

METHODS

We enrolled 76 patients with ILD and 24 controls in the current study. By using 1.5 T CMR scanner equipped with 32 channel cardiac coils, we performed steady-state free precession cine CMR to assess the RVEF. RV systolic dysfunction (RVSD) was defined as RVEF ≤45.0% calculated by long axis slices. Pulmonary hypertension (PH) was defined as mean pulmonary artery pressure (mPAP) of more than 25 mmHg at rest in the setting of pulmonary capillary wedge pressure ≤15 mmHg.

RESULTS

The median RVEF was 59.2% in controls (n = 24), 53.8% in ILD patients without PH (n = 42) and 43.1% in ILD patients with PH (n = 13) (p < 0.001 by one-way ANOVA). During a mean follow-up of 386 days, 18 patients with RVSD had 11 severe events (3 deaths, 3 right heart failure, 3 exacerbation of dyspnea requiring oxygen, 2 pneumonia requiring hospitalization). In contrast, only 2 exacerbation of dyspnea requiring oxygen were observed in 58 patients without RVSD. Multivariate Cox regression analysis showed that RVEF independently predicted future events, after adjusting for age, sex and RVFAC by echocardiography (hazard ratio: 0.889, 95% confidence interval: 0.809-0.976, p = 0.014).

CONCLUSIONS

The current study demonstrated that RVSD in ILD patients can be clearly detected by cine CMR. Importantly, low prevalence of PH (17%) indicated that population included many mild ILD patients. CMR derived RVEF might be useful for the risk stratification and clinical management of ILD patients.

Relationship between coronary flow reserve evaluated by phase-contrast cine cardiovascular magnetic resonance and serum eicosapentaenoic acid

BACKGROUND

Long-term intake of long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs), especially eicosapentaenoic acid (EPA) is associated with a low risk for cardiovascular disease. Phase-contrast cine cardiovascular magnetic resonance (PC cine CMR) can assess coronary flow reserve (CFR). The present study investigates the relationship between CFR evaluated by PC cine CMR and the serum EPA.

METHODS

We studied 127 patients (male, 116 (91%); mean age, 72.2 ± 7.4 years) with known or suspected coronary artery disease (CAD). X-ray coronary angiography revealed no significant coronary arterial stenoses (defined as luminal diameter reduction ≥ 50% on quantitative coronary angiogram (QCA) analysis) in all study participants. Breath-hold PC cine CMR images of the coronary sinus (CS) were acquired to assess blood flow of the CS both at rest and during adenosine triphosphate (ATP) infusion. We calculated CFR as CS blood flow during ATP infusion divided by that at rest. Patients were allocated to groups according to whether they had high (n = 64, EPA ≥ 75.8 μg/mL) or low (n = 63, EPA < 75.8 μg/mL) median serum EPA.

RESULTS

CFR was significantly lower in the low, than in the high EPA group (2.54 ± 1.00 vs. 2.91 ± 0.98, p = 0.038). Serum EPA positively correlated with CFR (R = 0.35, p < 0.001). We defined preserved CFR as > 2.5, which is the previously reported lower limit of normal flow reserve without obstructive CAD. Multivariate analysis revealed that EPA is an independent predictor of CFR > 2.5 (odds ratio, 1.01; 95% confidence interval, 1.00 - 1.02, p = 0.008).

CONCLUSIONS

The serum EPA is significantly correlated with CFR in CAD patients without significant coronary artery stenosis.

Esophageal fibrovascular polyp removed by cervical esophagotomy

We report a case of esophageal fibrovascular polyp (FVP) removed by cervical esophagotomy. The patient was a 74-year-old man in whom an intraesophageal mass was detected by a chest CT examination during a complete medical check-up. An upper gastrointestinal series showed a large, pedunculated, cervical esophageal mass for which our preoperative diagnosis was a FVP. We studied its features, as well as removal procedures in 45 patients in the literature. Most patients had marked symptoms, but ours had no complaints, and so this case may be a rare one. Various removal procedures were reported, but thoracotomy and esophagectomy are considered to be the inappropriate procedures since FVP is a benign disorder.

C-reactive protein elevation and rapid angiographic progression of nonculprit lesion in patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

In non-ST-segment elevation acute coronary syndromes (NSTE-ACS), the relation of the level of high-sensitivity C-reactive protein (CRP) to the progression of atherosclerosis remains unclear.

METHODS AND RESULTS

The study group comprised 153 patients with NSTE-ACS who underwent percutaneous coronary interventions (PCI) and follow-up (mean interval, 7 months) coronary angiography. Rapid progression was defined as > or =10% diameter reduction of a preexisting stenosis > or =50%, > or =30% diameter reduction of a stenosis <50%, development of a new stenosis > or =30% in a previously normal segment, or progression of any stenosis to total occlusion. Progressors had higher CRP levels on admission and at 48 h after PCI, a higher level of low-density lipoprotein cholesterol at follow-up, a higher rate of multiple complex lesions, and a lower frequency of statin use at follow-up than nonprogressors. Multivariate analysis showed that admission CRP elevation (CRP level on admission > or =0.166 mg/dl, median value; odds ratio (OR) 2.92, p=0.010), post-PCI CRP elevation (CRP level 48 h after PCI > or =1.586 mg/dl, median value; OR 2.67, p=0.022), and multiple complex lesions (OR 2.66, p=0.017) were independent predictors of rapid progression of nonculprit lesions.

CONCLUSIONS

Enhanced inflammatory response to PCI, as well as baseline inflammatory activity as reflected by CRP level, may be involved in the progression of atherosclerosis in NSTE-ACS.

Clinical implications of serial changes in ST-segment elevation after reperfusion in patients with anterior acute myocardial infarction

BACKGROUND

In patients with acute myocardial infarction (AMI), the relationship of serial changes in ST-segment elevation after reperfusion to left ventricular (LV) function remains unclear.

METHODS AND RESULTS

The study group comprised 164 patients with reperfused anterior AMI within 6 h of symptom onset. The sum of ST-segment deviation was calculated on admission (SigmaST-admission), and 1 h (SigmaST-1 h) and 24 h (SigmaST-24 h) after reperfusion. ST resolution was defined as a reduction in SigmaST-1 h of > or =50% as compared with SigmaST-admission. Patients were classified into 3 groups: group A, 82 patients with ST resolution in whom SigmaST-1 h > or = SigmaST-24 h; group B, 37 patients with ST resolution in whom SigmaST-1 h < SigmaST-24 h; group C, 45 patients without ST resolution. Peak creatine kinase were higher in groups B and C than in group A (4,578+/-2,176, 4,236+/-2,638, 2,222+/-1,926 mU/ml, p<0.01). At 6 months follow-up, the LV ejection fraction were lower in groups B and C than in group A (53+/-8, 54+/-12, 62+/-9%, p<0.01).

CONCLUSIONS

An increase in ST-segment elevation 1-24 h after reperfusion, despite ST resolution, is associated with a larger infarction and poorer LV function in patients with reperfused anterior AMI.

Pharmacokinetics and pharmacodynamics of febuxostat (TMX-67), a non-purine selective inhibitor of xanthine oxidase/xanthine dehydrogenase (NPSIXO) in patients with gout and/or hyperuricemia

The diurnal change of sUA and the effect of febuxostat on this change were investigated in 10 patients with gout and/or hyperuricemia. The diurnal sUA change after the last dose during the 4-week treatment phase (20 mg, QD) was almost the same as the pre-treatment value. Considering the dose, the AUC(obs) and Cmax of unchanged drug in patients with gout and/or hyperuricemia were estimated to be similar to those of healthy male adults. The results show that a 6-week treatment with febuxostat is safe and well-tolerated in the target patient population for this drug.

Continuous wave Doppler echocardiographic evaluation of St. Jude prosthetic mitral valves in children

The function of 9 St. Jude prosthetic mitral valves in 8 children was evaluated by continuous wave Doppler (CWD) echocardiography 28 +/- 22 months after implantation. All valves were apparently functioning normally on clinical examination. Peak flow velocity, mean flow velocity, pressure half-time and mean pressure gradient were determined from the transmitral flow velocity curve by CWD echocardiography. For comparison, the same parameters were examined in 15 normal children and 14 adults who had undergone mitral valve replacement. All measured values were greater in adults and children who had undergone valve replacement than in normal children. There were no differences in any parameter in adults or children in whom prostheses 25 mm or larger had been implanted. Although 3 children in whom prostheses 23 mm or smaller had been implanted had greater values for each parameter than those who received 25 mm or larger prostheses, there were no symptoms or signs of mitral stenosis. These data may be useful as guidelines for normal Doppler characteristics for St. Jude mitral valves in children. In an asymptomatic child whose prosthetic valve developed obstruction by granulation tissue overgrowth, each parameter significantly worsened as the heart rate increased. The changes in these parameters in 2 normally functioning St. Jude valves during atrial pacing were insignificant. The fluctuation of Doppler characteristics with changes in heart rate is useful for differentiating normally functioning prosthetic valves from impending stenosis.

[Surgical treatment of cor triatriatum: report of four cases]

Four cases of cor triatriatum are reported. Cases 1 and 2 had IIA, case 3 had IA, and case 4 had IIIB 1 type of cor triatriatum according to Lucas-Schmidt classification. Cases 1 and 2 were diagnosed by echocardiography preoperatively. They were not performed cineangiocardiography because of pulmonary congestion. Case 3 had type IA so called classical type, which is hemodynamically identical to mitral stenosis and supravalvular stenosing ring. The clinical features are depend on the size of the communication between accessory chamber and true left atrium. As case 4, he had been diagnosed of simple atrial septal defect preoperatively, careful echocardiographic examination was essential for accurate diagnosis. In case 2 with hypoplastic left heart, secondary surgical repair is considered to be desirable followed by balloon dilatation of two atrial septal defects communicated to accessory chamber and to true left atrium. Thus, we expect development of hypoplastic left ventricle.

Gustatory signal processing in the glossopharyngeo-hypoglossal reflex arc of the frog

The relationship between the gustatory input and motor output in the glossopharyngeo-hypoglossal reflex was analyzed on the basis of neuronal activities in the solitary tract and hypoglossal motor nuclei of bullfrogs. Concentration-response relations for NaCl, quinine and acetic acid, obtained from the glossopharyngeal (IXth) nerve and simultaneously recorded from the hypoglossal (XIIth) nerve, were expressed relative to the response of each nerve to 1 M NaCl. Compared with a relatively small amount of the afferent input for acid, the reflex motor output was much larger in the relative value. A similarly high output relation was obtained for warmed saline but not for quinine and cooled saline. Although the responsiveness of the nucleus tractus solitarius neurons to 1 M NaCl and 1 mM quinine was not significantly different from that of the hypoglossal motoneurons, responses to 10 mM acetic acid were greater in the latter neurons than in the former by a factor of about 5.2. These phenomena were consistent with those in the peripheral nerves. The solitary tract neurons responsive to NaCl, quinine and acid showed both the phasic and tonic components of discharges. According to classification by a transiency index, the discharge mode became more phasic for the hypoglossal motoneurons responsive to NaCl and quinine, but more tonic for those responsive to acid. The above-mentioned chemoreflex is thus regulated by the intrinsic neural network which sends signals to the XIIth nerve after modifying not only the amount but also the temporal pattern of gustatory nerve signals for a particular taste.