Use of echocardiography for predicting myocardial viability in patients with reperfused anterior wall myocardial infarction

Dobutamine stress echocardiography (DSE), myocardial contrast echocardiography (MCE), and ultrasonic tissue characterization with integrated backscatter are useful methods for assessing myocardial viability in acute myocardial infarction. In this study, we compared the potential of 3 methods for predicting myocardial viability in 38 patients with reperfused anterior wall acute myocardial infarction. We performed MCE shortly after coronary reperfusion with an intracoronary injection of microbubbles. We recorded 2-dimensional integrated backscatter images at rest and, then, performed low-dose (10 microg/kg/min) DSE 3 days later. In integrated backscatter images, we placed the region of interest in the midwall of the myocardial segment to reconstruct the cyclic variation of myocardial integrated backscatter. The myocardial segment was judged viable when it showed active contraction 3 months later. Among 74 segments analyzed, 34 were judged viable. Presence of contractile response during DSE predicted segmental viability with 91% sensitivity and 78% specificity. Intense and homogenous contrast enhancement with MCE predicted viability with 82% sensitivity and 73% specificity. The presence of synchronous contraction of cyclic variation predicted myocardial viability with 79% sensitivity and 83% specificity. There were no differences in sensitivity and specificity among the 3 methods. Thus, MCE and ultrasonic tissue characterization can predict myocardial viability as accurately as DSE in patients with acute myocardial infarction. The logistics of the methods may determine clinical application.

[Intravenous contrast echocardiography]

Intravenous contrast echocardiography has become possible in Japan because of the release of the commercially available contrast agent, Levovist. Intravenous administration of Levovist satisfactorily stains the left ventricular cavity, which makes it possible to clearly delineate the endocardial border. Clear delineation of the endocardial border provides easy and accurate measurement of left ventricular dimension and wall thickness, and wall motion abnormalities can be easily and accurately judged, too. Another benefit of intravenous contrast echocardiography is the assessment of myocardial perfusion. Our preliminary experimental and clinical experiences showed the possibility of myocardial staining with intravenous contrast echocardiography. Impressive myocardial staining is obtainable with the combined use of intermittent and contrast harmonic power Doppler imaging. In order to obtain reproducible and clear myocardial contrast images, we have to pay attention to how to inject contrast and settings of ultrasound equipment, i.e., mechanical index, gain setting, depth of focus point, and pulse repetition frequency, artifacts. In the near future, a lot of issues should be standardized to make it possible to compare myocardial contrast echo studies.

Use of the abdominal wall fat index determined ultrasonographically for assessing the risk of post-operative pulmonary embolism

OBJECTIVE

To assess the usefulness of the abdominal wall fat index (AFI) for predicting pulmonary embolism (PE) after gynecologic surgery.

METHOD

The subjects were 115 female patients who underwent laparotomy for gynecologic disease. They were divided into low-dose heparin therapy (n=28) and control, without heparin (n=87) groups. The AFI ratio of the maximum preperitoneal fat thickness to the minimum subcutaneous fat thickness was determined using ultrasonography.

RESULT

Post-operative PE occurred in four control patients. If the cut-off value of the AFI for predicting PE development was set at more than or equal to 0.85, the sensitivity was 1.00 and the specificity was 0.60 (P=0.03). If we restricted the criteria, and set the cut-off value of the AFI to more than or equal to 0.85 in patients with hypertension [systolic blood pressure (BP)>/=140 mmHg, diastolic BP>/=90 mmHg or patients were taking antihypertensive medication], the sensitivity and specificity were 0. 75 and 0.92, respectively (P=0.001).

CONCLUSION

Visceral fat obesity is a risk factor for PE after gynecologic surgery, and the AFI is useful for predicting PE and for whom post-operative low-dose heparin therapy may be indicated.

Sex chromosomal analysis of spermatozoa from infertile men using fluorescence in situ hybridization

PURPOSE

To confirm an association between male infertility and chromosome aberrations of spermatozoa, we demonstrated the frequency of numerical abnormalities of spermatozoa from infertile men with abnormal semen parameters compared with fertile controls.

METHOD

Sperm cells from 10 infertile patients were investigated for disomy rates of sex chromosomes and chromosome 18 and diploidy by fluorescence in situ hybridization (FISH). All patients showed oligoasthenozoospermia with sperm counts 3-20 x 10(6)/ml and motile rates 0-40%.

RESULTS

Regarding XY disomy, a significantly higher frequency was found in 8 of 10 patients as compared to normal fertile men. The disomy rates of chromosome 18, XX, YY, and diploidy rate were not increased.

CONCLUSIONS

There is an association between male infertility and embryo with aneuploidy of sex chromosomes. Counseling about possible genetic risks should be provided to the infertile couples planning assisted reproduction treatment.

Effects of bypass on ocular ischaemic syndrome caused by reversed flow in the ophthalmic artery

Superficial temporal to middle cerebral artery bypass was useful for ocular ischaemic syndrome caused by reversed flow in the ophthalmic artery as shown by ophthalmic-artery colour doppler flow imaging.

Early temporal changes in coronary flow velocity patterns in patients with acute myocardial infarction demonstrating the "no-reflow" phenomenon

Coronary flow velocity pattern in patients with acute myocardial infarction demonstrating no-reflow phenomenon is characterized with early systolic retrograde flow and rapid deceleration of diastolic flow velocity. In this study, we investigated the early temporal changes in microvascular function in patients with the no-reflow phenomenon. Among 144 patients with a first acute myocardial infarction, 33 exhibited sizable no-reflow phenomenon after coronary reperfusion with myocardial contrast echocardiography. We assessed temporal changes in coronary flow velocity patterns with the Doppler guidewire. The early systolic retrograde flow was observed < or = 10 seconds after reperfusion in 16 patients (group A) or later in 17 patients (331 +/- 327 seconds, group B). Diastolic deceleration rate was higher in group A than in group B at 1 minute after reperfusion. It gradually increased in group B and showed comparable value to group A 10 minutes later. Group A had longer elapsed time from symptom onset to reperfusion and a greater number of infarct Q waves before reperfusion than group B (14 +/- 13 vs 5 +/- 2 hours, p <0.01; and 3 +/- 2 vs 2 +/- 1, p <0.02). In contrast, the incidence of transient ST reelevation shortly after reperfusion was higher in group B (76% vs 25%, p <0.01). Thus, the characteristic coronary flow velocity pattern is either established at the moment of coronary reperfusion or progresses thereafter in patients with no-reflow phenomenon. This suggests different mechanisms of developing ischemic microvascular injury.

[Anesthetic management of a patient with Osler-Weber-Randu disease]

Osler-Weber-Randu disease (Osler disease) is an autosomal dominant disease, sometimes known as hereditary hemorrhagic telangiectasia with its family history. It is not a popular disease and approximately seventy families are known as inheritance lineage in Japan. We experienced anesthetic management of a 49-yr-old woman with Osler disease. She was diagnosed to have the brain abscess following fever and clouding of consciousness for several days and was scheduled for the removal of the abscess. A chest X-ray revealed pulmonary arteriovenous fistula in the right middle lung field. The patient had had life threatening frequent massive bleeding from her nose and/or stomach for the past several years. Her brother and children also had the same symptoms. In addition to Osler disease, the patient had the prolonged coagulation time that was supposed to the due to chronic liver disease. Therefore, fresh frozen plasma (5 units) and platelet concentrates (10 units) were infused during the surgery. Intraoperative blood loss was about 700 grams. We had no difficulties in management of bleeding and respiratory controls during anesthesia.

Comparison of predictive value for colorectal cancer in subjects with and without rectal bleeding

BACKGROUND/AIMS

To clarify the association between a sign of rectal bleeding and colorectal cancer, and to reveal the relationship of rectal bleeding to the results of an immunochemical fecal occult blood test.

METHODOLOGY

In a population-based cross sectional study, 30,138 subjects who received immunochemical fecal occult blood screening with a 2-day method were divided into two groups, according to the results of a questionnaire on a sign of rectal bleeding, and the positivity rate of an immunochemical occult blood test as well as the predictive value for colorectal cancer were compared in the two groups.

RESULTS

The fecal occult blood test was positive in 8.8% of subjects with rectal bleeding and in 6.0% of subjects without rectal bleeding, and the predictive value was 6.4% and 3.3% in subjects with and without rectal bleeding, respectively, showing a significant difference in the positivity rate (p<0.001) as well as the predictive value (p<0.05) between these two groups.

CONCLUSIONS

These findings indicate that there are positive relations between the subjects with rectal bleeding presentation and colorectal cancer, and a sign of rectal bleeding and the results of an immunochemical fecal occult blood test.

Intravenous nicorandil can preserve microvascular integrity and myocardial viability in patients with reperfused anterior wall myocardial infarction

OBJECTIVES

We assessed whether the intravenous administration of nicorandil, an adenosine triphosphate (ATP)-sensitive K+ channel opener, exerts beneficial effect on microvascular function and functional and clinical outcomes in patients with acute myocardial infarction (AMI).

BACKGROUND

Experimental studies documented that ATP-sensitive K+ channel opener exerts cardioprotection after prolonged ischemia.

METHODS

We randomly divided 81 patients with a first anterior AMI into two groups, nicorandil (n = 40) and control groups (n = 41). All patients received successful coronary angioplasty within 12 h after the symptom onset and underwent myocardial contrast echcardiography (MCE) with the intracoronary injection of sonicated microbubbles. In the nicorandil group, we injected 4 mg of nicorandil followed by the infusion at 6 mg/h for 24 h and by oral nicorandil (15 mg/day).

RESULTS

The improvement in regional left ventricular function, wall motion score and regional wall motion was significantly better in the nicorandil group then in the control group. Intractable congestive heart failure, malignant ventricular arrhythmia and pericardial effusion were more frequently found in the control group than in the nicorandil group (15% vs. 37%, 5% vs. 20% and 8% vs. 37%, p < 0.05, respectively). The frequency of sizable MCE no reflow phenomenon was significantly lower in the nicorandil group than in the control group (15% vs. 33%, p < 0.05).

CONCLUSIONS

Intravenous nicorandil in conjunction with coronary angioplasty is associated with better functional and clinical outcomes compared to angioplasty alone in patients with an anterior AMI. Myocardial contrast echocardiography findings imply that an improvement in microvascular function with nicorandil may be attributable to this better outcome.

[The effect of epidural anesthesia on reducing blood loss during upper abdominal surgery]

We examined the advantage of the combined epidural anesthesia with general anesthesia for the upper abdominal surgery One hundred and thirty-five gastric cancer patients were subjected to the study. They were divided into four groups. Group A (n = 46) and B (n = 44) received distal gastrectomy, and group C (n = 27) and D (n = 18) received total gastrectomy. In group A and C, anesthesia was maintained with combined epidural and general anesthesia. In group B and D, only general anesthesia was administered. We compared group A versus B and groups C versus D. The parameters for the comparisons were intraoperative blood loss, averaged mean blood pressure, surgical operation time, etc. The patient background was not different between group A and B, and also between group C and D. The blood loss and mean blood pressure were significantly lower in groups A and C than in groups B and D. But there was no correlation between the blood loss and mean blood pressure. The results suggest that the fall of the mean blood pressure is one of the causes of reduced blood loss, but the causes may include other complicated parameters. We conclude that the combined use of epidural anesthesia with general anesthesia is useful for reducing the amount of blood loss for upper abdominal surgery.

Antecedent angina pectoris as a predictor of better functional and clinical outcomes in patients with an inferior wall acute myocardial infarction

We examined whether angina pectoris (AP) occurring shortly before the onset of acute myocardial infarction (AMI) can render the right ventricle and the conducting tissue resistant to ischemia in 75 patients with an inferior wall AMI. Each patient had total occlusion in the proximal right coronary artery and underwent successful coronary angioplasty < or =24 hours from the onset. We divided patients into 2 groups based on presence or absence of antecedent AP < or =24 hours before the system onset: group 1 (absent) = 57 patients; group 2 (present) = 18 patients. Collateral circulation was more frequently observed in group 2 than in group 1 (group 1 vs 2, 28% vs 61%, p <0.01). Elevation in ST segment > or =1 mm in lead V4R, hemodynamic right ventricular dysfunction, and frequency of high-degree heart block were more frequent in group 1 than in group 2 (75% vs 44%, 79% vs 39%, 53% vs 11%, p <0.05, respectively). Multivariate analysis demonstrated that antecedent AP is the only factor related to these complications. Thus, episodes of AP occurring shortly before onset may restrain development of ischemic damage of the right ventricle and conducting tissue, and are associated with better clinical and functional outcomes among patients with an inferior wall AMI.

[Propofol combined with epidural anesthesia for a patient complicated with myelodysplastic syndrome (MDS)]

A 55 year-old-female with myelodysplastic syndrome (MDS) underwent hemi-colectomy. We planned to avoid the use of nitrous oxide, because of its myelo suppressive effects. Therefore, we maintained the anesthesia with propofol combined with epidural anesthesia. After the surgical operation, the patient developed no hematological complications.

[Effect of the continuous epidural buprenorphine injection in patients after lower extremity arthroplasty]

We studied the analgesic effects of continuous epidural injection of buprenorphine in patients after lower extremity arthroplasty. In these patients anesthesia was maintained only with lumbar epidural anesthesia with 2% mepivacaine. We employed a balloon type continuous infuser (DIB Catheter, 40 ml.day-1) for postoperative analgesia for twenty-four hours. The patients were classified into three groups according to the method of buprenorphine injection and the content of DIB Catheter. First group (group A ; N = 37) received buprenorphine (0.2 mg) with 0.25% bupivacaine (40 ml) for twenty-four hours. Next group (group B ; N = 27) received bolus injection of buprenorphine (0.2 mg) for the first additional epidural injection of local anesthetic and received continuous injection of buprenorphine (0.2 mg) with 0.25% bupivacaine (40 ml) for twenty-four hours. The last group (Group C ; N = 40) also received bolus injection of buprenorphine as in group B, but received continuous buprenorphine infusion with normal saline instead of local anesthetics. The analgesic effect was determined by the postoperative usage of other analgesics (NSAID or pentazocine) by request of patients. In twenty-four hours, the numbers of patients who did not request other analgesics were 6 (Group A. 16%), 9 (Group B. 33%) and 19 (Group C. 48%), respectively. In Group A, 18 patients requested analgesics, but only 8 patients requested in Group C. It was effective for the postoperative analgesia to use the continuous epidural injection with DIB Catheter for patients after lower extremity arthroplasty. It was necessary to give a bolus injection of buprenorphine before the end of surgery for sufficient analgesia, but it was not necessary to add local anesthetics in the content of DIB Catheter.

Ultrasonic tissue characterization predicts myocardial viability in early stage of reperfused acute myocardial infarction

BACKGROUND

The aim of the present study was to characterize temporal changes in cyclic variation of ultrasonic integrated backscatter (IBS), which reflects intrinsic contractile performance, in patients with reperfused acute myocardial infarction (AMI) and to elucidate the clinical value of tissue characterization in predicting myocardial viability.

METHODS AND RESULTS

We recorded short-axis IBS images before and 3, 7, and 21 days after reperfusion in 26 patients with AMI and obtained the cyclic variation of IBS in the normal and infarct zones. When cyclic variation showed synchrony and asynchrony, we expressed its magnitude as positive and negative values, respectively, called the phase-corrected magnitude. We also measured average wall motion score (dyskinesis, 4; normal, 0) of the infarct segments. The phase-corrected magnitude was lower in the infarct zone than in the normal zone before reperfusion (0.3+/-2.5 versus 5.2+/-1.7 dB, P<.05). At day 3, the phase-corrected magnitude increased by 2.1+/-2.6 dB despite no improvement in wall motion. Improvement in wall motion was observed only at day 21. The patients with the phase-corrected magnitude of > or =2.0 dB at day 3 showed significantly lower wall motion score at day 21 than did the other patients (1.7+/-0.6 versus 2.4+/-0.5, P<.01).

CONCLUSIONS

In patients with AMI, cyclic variation of IBS is blunted during ischemia but recovers much faster after reperfusion than the improvement in wall motion. The greater phase-corrected magnitude at day 3 may be a predictor of better functional improvement.

A new pseudo-peptide of Arg-Gly-Asp (RGD) with inhibitory effect on tumor metastasis and enzymatic degradation of extracellular matrix

A series of pseudo-peptide analogs of the Arg-Gly-Asp (RGD) sequence of fibronectin have been synthesized, and their anti-metastatic effects in mice and inhibitory effects on tumor cell invasion in vitro have been examined. The partially modified retro pseudo-peptide of RGD, Rrev-COCH2CO-D (FC-63), was more effective in inhibiting tumor metastasis than the original RGDS peptide. Replacement of the malonyl moiety of FC-63 with a carboxyethylene linkage (Rrev-COCH2CH2-D, FC-303 ) achieved more potent inhibition of lung metastasis of melanoma cells than FC-63. Among the analogs, FC-336, a p-xylylendiamine derivative having two FC-303 moieties, showed the most potent inhibitory effect on experimental lung metastasis produced by i.v. co-injection with B16-BL6 melanoma or colon 26 M3.1 cells in a dose-dependent manner. Multiple administrations of FC-336 after tumor inoculation also showed efficient therapeutic potency against spontaneous lung metastasis of B16-BL6 melanoma in mice. Furthermore, FC-336 effectively inhibited the invasion, migration and adhesion of tumor cells in vitro, but its inhibitory effects were not more than those of RGDS peptide. Zymography analysis revealed that FC-336 inhibited the degradation of gelatin substrate by matrix metalloproteinases (MMPs) produced by tumor cells, while the RGDS peptide did not affect the enzymatic degradation. These findings indicate that the pseudo-peptides of the RGD sequence, possessing the inhibitory property of the degradation by MMPs differently from original RGD-containing peptides, may be advantageous and useful in preventing tumor metastasis.

Beneficial effect of intracoronary verapamil on microvascular and myocardial salvage in patients with acute myocardial infarction

OBJECTIVES

We assessed the acute effect of intracoronary injection of verapamil on microvascular function after primary percutaneous translumanal coronary angioplasty (PTCA) for acute myocardial infarction (AMI) with myocardial contrast echocardiography (MCE) in relation to functional outcomes.

BACKGROUND

Recent clinical studies have documented the potential of verapamil for possible increase in coronary blood flow after primary PTCA.

METHODS

Forty patients with a first AMI were randomly assigned to the verapamil group (n = 20) or the control group (n = 20). In the verapamil group, verapamil (0.5 mg) was injected into the infarct-related artery shortly after PTCA, followed by the oral administration. We performed MCE with an intracoronary injection of sonicated microbubbles before and after verapamil. To assess microvascular integrity, we determined the baseline-subtracted peak intensity in the risk area and the ratio of the no reflow zone plus the low reflow zone to the risk area (low reflow ratio). We determined the average wall motion score (dyskinesia/akinesia = 3; normal = 0) in the risk area on the day of AMI and a mean of 24 days later.

RESULTS

The low reflow zone was observed shortly after PTCA in 14 verapamil group patients, and the low reflow ratio decreased after verapamil (0.39 +/- 0.23 vs. 0.29 +/- 0.17 [mean +/- SD], p < 0.05). Peak intensity significantly (p < 0.05) increased from 6 +/- 5 to 12 +/- 6 after verapamil. The reduction in wall motion score from the acute (day -1) to the late stage (day -24) was significantly greater in the verapamil group than in the control group (0.7 +/- 0.8 vs. 0.2 +/- 1.3, respectively, p < 0.05).

CONCLUSIONS

Intracoronary administration of verapamil after primary PTCA can attenuate microvascular dysfunction and thereby augment myocardial blood flow in patients with AMI, leading to better functional outcome than with PTCA alone.

Enrichment of oligo(dG).oligo(dC)-containing fragments from human genomic DNA by Mg 2+-dependent triplex affinity capture

Oligo(dG).oligo(dC)- or short poly(dG).poly(dC)-containing fragments were enriched and cloned by means of Mg2+-dependent triplex affinity capture and subsequent cloning procedures. A library constructed after three cycles of enrichment showed that approximately 80% of the clones in the supercoiled form formed a complex with labeled oligonucleotide (dG)34. However, while the rest of the clones retained the ability to form a complex (type I clones), 90.9% failed to form a complex when they were linearized. This group of DNA was abundant in the genomic DNA, although it showed only approximately 3-fold enrichment by one cycle of affinity capture. This group was further classified into two species (types II and III) based on complex formation ability after phenol extraction. Type II clones retained the complex formation ability after treatment, while the human telomere [(TTAGGG)n] and telomere-like [(TGGAA)n] or [(TGGAG)n] sequences belonging to type III clones did not. Serial deletion experiments and the binding assays using oligonucleotides confirmed that the repetitive units containing T(G)nT ( n = 3-5) tracts or (G)n-motifs (n >/= 3) were the sites of complex formation for type II and III clones. On the other hand, type I clones contained poly(dG).poly(dC) tracts at least 10 nt long, and DNase I-footprinting analysis indicated that these tracts were the sites of complex formation.

[Optic neuritis and measles infection]

Optic neuritis has been reported as a complication of measles encephalitis. This resembles to parainfectious optic neuritis following other virus infections. We mentioned pathology, therapy of this disease, and summarized our previous cases. Intravenous methylpredonisolone treatment is effective from our experience.

An approach to the detection of autonomic neuropathy by use of signal-averaged electrocardiography

The beat-to-beat variation of PR interval, which is thought to be a reflection of autonomic nervous system, is difficult to measure with accuracy because the variation is too subtle. However, R wave amplitude in the P wave triggered SAECG is easily attenuated in comparison to that in the R wave triggered SAECG, which might be due to PR interval fluctuation. To determine whether autonomic neuropathy could be detected by use of SAECG, two types of SAECGs triggered by P and R waves were recorded in 23 diabetics with autonomic neuropathy and 41 age matched controls. The peak voltage of filtered QRS complex was measured in the R wave and P wave triggered SAECGs. Percent attenuation of the filtered QRS voltage was calculated by dividing the difference between the voltages in the R wave and P wave triggered SAECGs by the voltage in R wave triggered SAECG. The percent attenuation of filtered QRS voltage was significantly smaller in diabetics with autonomic neuropathy than controls (4.6% +/- 4.9% vs 16.3% +/- 15.0%; P < 0.001). These results suggest that the degree of attenuation of filtered QRS voltage in the P wave triggered SAECG would be useful for the detection of autonomic neuropathy.

Liposomal Arg-Gly-Asp analogs effectively inhibit metastatic B16 melanoma colonization in murine lungs

Analogs of a synthetic peptide having the L-arginine-L-glycine-L-aspartic acid (RGD) sequence have been found to decrease metastatic colonization. To enhance the metastasis-suppressing efficacy of these analogs, we sought to stabilize these analogs and to prolong their circulation time by incorporating them into a liposomal formulation. Various structures of RGD analogs grafted to hydrophobic groups were synthesized and then incorporated into liposomes. Liposomes composed of distearoylphosphatidylcholine, cholesterol, dipalmitoylphosphatidylglycerol and appropriate RGD analogs were injected intravenously along with B16BL6 murine melanoma cells into mice. Liposomal RGD (0.6 mumol of the analog equivalent to ca. 200 micrograms RGD peptides) inhibited lung colonization up to 76%. This dose is an order of magnitude lower than that for comparable inhibition reported for free RGD. Multi-dose administration of liposomal RGD (0.15 mumol of the analog) also inhibited the spontaneous lung metastasis of cells from a primary tumor site of B16BL6 cells subcutaneously implanted into the footpad of mice. Taken together, our data indicate that liposomal RGD may serve as a useful anti-metastatic agent.

Construction of a human genomic library of clones containing poly(dG-dA).poly(dT-dC) tracts by Mg(2+)-dependent triplex affinity capture. DNA polymorphism associated with the tracts

Microsatellite DNA is a useful tool for detecting DNA polymorphisms among species or individuals, especially those among closely related individuals. We constructed a library of clones that contained poly(dG-dA).poly(dT-dC) tracts from human genomic DNA by Mg(2+)-dependent triplex DNA formation. Examination of triplex DNA formation in the presence of various metal ions Mg2+, Mn2+, or Zn2+ revealed that the procedure worked best in the presence of Mg2+. Affinity enrichment was performed with AluI-digested chromosomal DNA mixed with biotinylated (dG-dA)17 in the presence of Mg2+. A library constructed after three cycles of affinity enrichment showed that over 80% of the clones contained at least one poly(dG-dA).poly(dT-dC) tract. Most of them contained a perfect (dG-dA)n repeat 30-84 base pairs in length, while some contained variants such as (dC-dT)10-(dC)-(dC-dT)9. Using the clones from the library as a probe, we detected DNA polymorphisms associated with the repeat length of the tracts in the Japanese population. We also detected a microsatellite instability among the tracts in a cancer tissue sample.

Effect of acoustic overstimulation on the hydropic ear

The effect of acoustic overstimulation (2 kHz pure tone) on the compound action potential (CAP) threshold was investigated at frequencies ranging from 2 to 16 kHz using albino guinea pigs, both normal and with experimentally induced endolymphatic hydrops. The hydropic ears were less susceptible to acoustic overstimulation than the normal ears. As the CAP threshold was raised, the frequency exhibiting the greatest CAP threshold shift increased in both animal groups. The tendency was more noticeable in the hydropic ears than in the normal ears. These results are discussed from the aspect of cochlear hydrodynamics.