Effects of endothelin-1 on coronary microcirculation in isolated beating hearts of rats

An intravital fluorescence videomicroscope system was used to investigate the pharmacological effects of endothelin-1 (ET-1) on the coronary microcirculation in isolated beating hearts of rats. The heart was perfused by retrograde aortic steady flow with an oxygenated Krebs-Ringer solution containing FITC-dextran. Cumulative injections of ET-1 (1-30 pmol) elicited a dose-dependent increase in perfusion pressure from 52 +/- 15 mm Hg (mean +/- SEM; n = 6) before the ET-1 injection to 104 +/- 23 mm Hg at the ET-1 dose of 30 pmol. A dose-dependent narrowing of microvessels was also observed on a monitor screen. This diffuse vasoconstriction was especially prominent in small arterioles; the maximum vasoconstriction of the smaller arterioles was significantly higher than that of the larger arterioles. These findings suggest that ET-1 may have an important role in governing the coronary resistance and regulating the capillary flow in myocardium.

Involvement of endothelin in the regulation of human vascular tonus. Potent vasoconstrictor effect and existence in endothelial cells

Endothelin, a recently discovered endothelium-derived peptide, has been reported to produce potent vasoconstriction in various vessels of experimental animals. To study the involvement of endothelin in the regulation of vascular tonus in humans, isolated human mesenteric arteries were investigated by both pharmacological and immunohistochemical methods. The vasoconstrictor action of endothelin-1 was examined on ring segments of human mesenteric arteries. Endothelin-1 induced a slowly developing and sustained contraction, with an EC50 value (half-maximal effective concentration) of 2.9 x 10(-9) M, two orders of magnitude smaller than that of norepinephrine (EC50 of 3.9 x 10(-7) M), indicating that the vasoconstrictor action of endothelin-1 is about 100 times more potent than that of norepinephrine. The contractile effect of endothelin-1 was affected neither by adrenergic, cholinergic, histaminergic, nor serotonergic antagonists, nor by inhibitors of arachidonic acid metabolism. The vasoconstrictor response to endothelin-1 was effectively antagonized by nicardipine, a dihydropyridine Ca2+ channel blocker. Endothelin-1 profoundly augmented contractile response to Ca2+ in partially depolarized tissues. Immunohistochemical studies revealed for the first time that endothelin-like immunoreactivity was localized in endothelial cells of human mesenteric artery. The results of the present study indicate that endothelin-1 is one of the most potent vasoconstrictors in the human mesenteric artery and that it induces vasoconstriction via an ultimately accelerating Ca2+ influx through voltage-dependent Ca2+ channels. Since endothelin-1 can be located in human endothelial cells, it may play an important physiological or pathophysiological role.

Effects of acutely impaired regional function on remote myocardial wall motion and blood flow in the canine left ventricle studied by coronary occlusion and hypoxic perfusion

STUDY OBJECTIVE

The aim was to examine whether regional myocardial dysfunction has a significant effect on the wall motion and blood flow in remote non-ischaemic regions.

DESIGN

Two different severities of regional dysfunction were produced by occluding the left anterior descending coronary artery and perfusing it with a hypoxic solution. Haemodynamic variables were otherwise identical in the two conditions. The relationship of regional dysfunction in the left anterior descending artery region to regional wall motion and regional myocardial blood flow in the left circumflex artery region were examined.

EXPERIMENTAL MATERIAL

22 anaesthetised mongrel dogs, 9-16 kg, were used for the studies: 14 for the regional wall motion studies, and eight for the regional myocardial blood flow studies.

MEASUREMENTS AND MAIN RESULTS

Segment shortening in the left anterior descending artery region was impaired differently in the two conditions: arterial occlusion caused a bulge, while hypoxic perfusion caused only mild hypokinesis. Segment shortening and the myocardial blood flow in the left circumflex artery region were augmented similarly in the two conditions. Left ventricular end diastolic pressure and end diastolic segment length in the left circumflex region were increased and aortic pressure was slightly decreased by left anterior descending artery occlusion and hypoxic perfusion, but there was no significant difference between the two conditions. Heart rate was not affected.

CONCLUSION

The augmentation of wall motion and blood flow of the remote myocardium does not depend on the magnitude of acutely induced regional dysfunction per se. The augmented wall motion in the remote region is unlikely to be due to mechanical unloading of the remote myocardium due to an intraventricular regional interaction, but rather to the Frank-Starling mechanism and left ventricular afterload reduction following acute ischaemia.

Mechanical and non-mechanical factors in hypertensive hypertrophy, their clinical roles

To investigate the clinical roles of mechanical and non-mechanical factors in hypertensive hypertrophy, 125 patients with essential hypertension, 20 with hypertrophic cardiomyopathy (HCM) and 20 with dilated cardiomyopathy (DCM), were studied using echocardiography. The hypertensive patients were separated into 3 groups: those with left ventricular (LV) hypertrophy (H), those without hypertrophy (H(-)) and those with dilatation (D). Group H patients were separated into 3 subgroups: those with subnormal LV end-systolic wall stress (ESS) (HI), those with normal ESS and mild hypertrophy (HIIA), and those with normal ESS and severe hypertrophy (HIIB). The inotropic response to isoproterenol infusion (0.02 microgram/kg/min for 5 min) was measured by the increase of fractional shortening (FS) corrected for the decrease of ESS (delta FS/delta ESS). After antihypertensive treatment for 4.4 +/- 1.7 years, echocardiography was repeated. delta FS/delta ESS was significantly larger in HI and HCM than in HIIA, was significantly larger in HIIA than in HIIB in which it was significantly larger than in D and DCM. After the treatment, LV mass decreased significantly except in HI. In conclusion, hypertensive hearts are regulated by mechanical and non-mechanical factors. Non-mechanical factors, for example the function of beta-adrenergic receptors in myocardium, have a variety of influences on myocardium, causing a broad spectrum of clinical features and courses.

Mechanisms of stress-induced ST elevation and negative T-wave normalization studied by serial cardiokymogram in patients with a previous myocardial infarction

Seventeen patients with a previous myocardial infarction were studied during pacing to characterize the clinical correlates of ST elevation, to analyze the relation between ST elevation and negative T-wave normalization and to investigate the mechanism of these electrocardiographic changes. Myocardial ischemia was evaluated by measurement of blood lactate, and wall motion was analyzed using cardiokymographs concurrently and serially. Results show that ST elevation and negative T-wave normalization were most marked in leads containing abnormal Q waves, that ST elevation greater than or equal to 1 mm during pacing was associated with a significant increase in left ventricular end-diastolic pressure and deterioration of left ventricular wall motion and that the magnitude of ST elevation and negative T-wave normalization was significantly correlated, but the latter appeared earlier and more markedly. In addition, there was no significant correlation between the extent of either ST elevation or negative T-wave normalization and myocardial lactate production. Thus, ST elevation and negative T-wave normalization are caused by abnormal left ventricular wall motion rather than myocardial ischemia. Negative T-wave normalization is a more sensitive marker of abnormal wall motion than ST elevation in patients with a previous myocardial infarction.

Echocardiographic and electrocardiographic study of the normal kangaroo heart

Healthy kangaroos are prone to sudden death. To investigate possible causes of this phenomenon, echocardiographic and electrocardiographic studies were conducted in seven healthy sedated (intramuscular ketamine 20 mg/kg, xylazine 2 mg/kg) kangaroos aged 1.5-5 years weighing 5.5-48 kg. As in human hypertrophic cardiomyopathy, kangaroos showed relative left ventricular hypertrophy measured as a ratio of (internal left ventricular end-diastolic diameter)/(septal + posterior wall thickness): 1.7 (SD 0.2) in kangaroos and 1.3 (SD 0.4) in hypertrophic cardiomyopathy cf 2.6 (SD 0.6) in normal man (p less than 0.001 respectively). Peak left ventricular diastolic filling velocity was smaller in kangaroos (2.6 (SD 0.3)/sec) and hypertrophic cardiomyopathy (3.3 (SD 0.7)/sec) than in normal man (4.1 (SD 1.0)/sec) (p less than 0.01, p less than 0.05). The end of T wave occurred earlier than the closing of aortic valve. Corrected QT interval (0.20 (SD 0.02) sec) was shorter than the normal value for man (0.34-0.40 sec). In conclusion, kangaroos have cardiac hypertrophy of unknown aetiology, with impaired diastolic function, as in non-obstructive hypertrophic cardiomyopathy patients. Corrected QT interval was short. These echocardiographic and electrocardiographic findings may explain the mechanism of sudden death in kangaroos, a species which may be used as an experimental model of non-obstructive hypertrophic cardiomyopathy in man.

Diurnal change of giant negative T wave in patients with hypertrophic cardiomyopathy

To examine the diurnal change of negative T wave (deeper than 10 mm in precordial leads) in apical hypertrophic cardiomyopathy and the mechanism of giant negative T wave, 24-h ambulatory electrocardiographic monitoring was performed in 8 patients with apical hypertrophic cardiomyopathy, and effect of atropine on electrocardiogram was studied. The mean depth of negative T wave at 1, 2, and 3 P.M. was 9.3 +/- 3.0 mm, and that at 1, 2, and 3 A.M. was 12.6 +/- 4.8 mm. The mean R-R interval at 1, 2, and 3 P.M. was 792 +/- 113 ms and that at 1, 2, and 3 A.M. was 1055 +/- 94 ms. In seven patients (88%), negative T wave was deeper during the night than during the daytime. There was a positive correlation between R-R interval and depth of negative T wave in 6 patients (75%). Despite significant shortening of R-R interval (879 +/- 116 to 804 +/- 110 ms, p less than 0.05), atropine did not significantly change the depth of negative T wave (14 +/- 5 to 14 +/- 5 mm). In conclusion, negative T wave is not fixed, but is variable, diurnally, probably due to the change of sympathetic tone.

New trend of cardiac imaging--intravenous coronary arteriography by synchrotron radiation

Synchrotron radiation is a broadspectrum intense X-ray beam. Selected X-ray wavelength was obtained by Bragg reflex. That is a monochromatic beam, which has a high spatial resolution, and has a K-edge discontinuity in attenuation coefficient, which, by energy subtraction, contributes to improve time resolution. An attempt to apply this method to intravenous coronary arteriography was performed in 7 anesthetized dogs. The beam was obtained by synchrotron radiation from accumulation ring, was reflected by silicon crystal, and was detected by 7 inch image intensifier system. Two-dimensional real time images were recorded on video tape. Phantom experiment was also performed. In dogs, coronary arteries were clearly distinguished by synchrotron radiation, especially at real time by video system. Phantom experiment suggested that coronary arteries could be visualized even over the visualized left ventricle. In conclusion, synchrotron radiation using two-dimensional real time images is expected to be useful in intravenous coronary arteriography in man.

Cardiac determinants of regression of left ventricular hypertrophy in essential hypertension with antihypertensive treatment

To study the cardiac determinants of regression of left ventricular hypertrophy in hypertension, left ventricular mass, fractional shortening and end-systolic wall stress were measured echocardiographically in 36 patients with essential hypertension and left ventricular hypertrophy. The patients were classified into two groups. Group I consisted of 15 patients with subnormal end-systolic wall stress, and Group II consisted of 21 patients with normal end-systolic wall stress. There were no significant differences between groups in systolic or diastolic blood pressure. After treatment for 4.4 +/- 1.7 years, echocardiographic studies were repeated. There were no significant differences between groups in the duration of the follow-up period and the kinds of antihypertensive drugs. After treatment, blood pressure decreased significantly in both groups (p less than 0.001 for both), with no significant difference between groups. Left ventricular mass increased significantly in Group I (from 331 +/- 7 to 363 +/- 24 g, mean +/- SEM, p less than 0.05), whereas it decreased significantly in Group II (from 318 +/- 16 to 268 +/- 17 g, p less than 0.001). Myocardial contractility (the relation between end-systolic wall stress and fractional shortening) remained almost the same as before treatment. In conclusion, in patients with hypertensive ventricular hypertrophy with subnormal end-systolic wall stress (inappropriate hypertrophy, probably induced by a neurohumoral factor), a decrease in blood pressure with antihypertensive treatment does not lead to regression of left ventricular hypertrophy, but rather to an increase in left ventricular mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up study of the heart in acromegaly: pre- and post-operative evaluation

Pre-operative and post-operative echocardiographic data were analyzed from 8 patients with acromegaly. Pre-operatively, end-diastolic diameter was greater than 55 mm in 5 patients (63%) and concentric left ventricular hypertrophy was observed in 3 patients (38%). However, left ventricular function was normal (fractional shortening of the left ventricle greater than 28%) in all patients except 1. All patients had increased left ventricular mass. There was no significant correlation between left ventricular mass and basal plasma growth hormone concentration. An average of 23.9 months after hypophysectomy, growth hormone concentration was significantly decreased. However, the abnormal echocardiographic findings remained. In conclusion, echocardiographic abnormalities (left ventricular dilatation and hypertrophy) are common in patients with acromegaly, but systolic function is, in general, maintained. These cardiac abnormalities persist after reduction of plasma growth hormone concentration.

[New trends in diagnostic examinations in clinical cardiology]

There are various kinds of diagnostic examinations in the field of clinical cardiology. In this field, information concerning cardiac structure, dimensions (hypertrophy and dilatation) and cardiac functions are inevitably important. Noninvasive methods are desirable. Except for radiological examinations, electrocardiography and ultrasonic echocardiography are 2 main examinations in cardiology. Holter monitoring is one of the recent topics in clinical electro-cardiology. It is useful for the detection of rest angina or variant angina. Recently "silent myocardial ischemia" has been studied by using this method. This method is also useful for the study of arrhythmia, which is a major cause of sudden death. Quantitative analysis of arrhythmia in the studies of antiarrhythmic drugs can also be done by Holter monitoring. Late potential is also a topic in electro-cardiology. Ultrasonic echocardiography can detect the changes of cardiac structure and function. Doppler echocardiography, developed recently, has made it possible to estimate intracardiac pressure (especially pulmonary arterial pressure) noninvasively. With esophageal echocardiography findings in left atrium, such as thrombus or myxoma in left atrium can be obtained. The most appropriate tool must be selected from the many kinds of diagnostic examinations for efficient clinical diagnosis and therapy.

Characteristics of pressor response to endothelin in spontaneously hypertensive and Wistar-Kyoto rats

Endothelin, an endothelium-derived vasoconstrictor peptide, and angiotensin II were intravenously injected into the femoral vein of normotensive Wistar-Kyoto (WKY) rats that had been anesthetized with urethane. Blood pressure and heart rate were recorded from a cannula inserted into the carotid artery. All experiments were carried out after treatment with adrenergic and cholinergic antagonists. Endothelin showed a potent, dose-dependent pressor action. The dose-response relations for the increase in blood pressure of rats receiving endothelin were comparable with those of rats receiving angiotensin II. However, endothelin showed far more long-lasting effects. Endothelin-induced responses consisted of three phases: a rapid and transient depressor phase and then two phases of pressor (transient and long-lasting) response. Nicardipine (0.1 mg/kg), a dihydropyridine Ca2+ channel blocker, markedly attenuated the slow phase of the pressor response but only slightly attenuated the rapid one. The pressor action of endothelin was not inhibited by continuous infusions of saralasin, which almost abolished the angiotensin II-induced pressor response. Endothelin-induced pressor response was also not attenuated by indomethacin, a prostaglandin synthesis inhibitor. These data provide evidence that endothelin produces a unique, potent, and long-lasting pressor response, which appears to be in part related to the activation of Ca2+ channels. In 12-week-old spontaneously hypertensive rats (SHR), the maximal pressor response to endothelin was slightly but significantly greater than that in age-matched WKY rats, but the dose dependency of the response was approximately consistent with that in WKY rats.(ABSTRACT TRUNCATED AT 250 WORDS)

[Quantitative evaluations of left ventricular function obtained by electrocardiographically-gated magnetic resonance imaging]

Using electrocardiographically-gated magnetic resonance imaging, regional cardiac function was evaluated in 12 normal volunteers and in 10 cases of old myocardial infarction. The optimal short axis of the left ventricle was selected at the chordae tendineae level. The left ventricle was divided into 12 segments using a computer-aided system, and percentile shortening fraction (%SF) and percentile wall thickening (%WT) were calculated in each segment by the fixed coordinate method. In the normal volunteers, heterogeneity of both %FS and %WT was observed, ranging from 25 +/- 13% and 37 +/- 13%, respectively in the septal segment, to 49 +/- 13% and 60 +/- 21%, respectively in the posterior segment. In the cases of myocardial infarction, decreased %FS and %WT were detected at the affected regions. The abnormal regions revealed by %WT tended to be narrower than those revealed by %FS. Thus the MR technique at the optimal axis may be useful for quantitative evaluations of regional cardiac function.

Isoproterenol stress thallium scintigraphy for detecting coronary artery disease

The value of exercise thallium scintigraphy in detecting coronary artery disease is well established. However, there are at times situations in which the exercise test cannot be readily used. Isoproterenol (ISP) stress ECG (ISP-ECG) is reportedly a useful method in diagnosing coronary artery disease. In the present study, we assessed the diagnostic value of ISP thallium scintigraphy, comparing it with those of ISP-ECG and exercise thallium scintigraphy. The study population consisted of 24 patients who had histories of chest pain without previous myocardial infarction. ISP was given at increasing doses of 0.02, 0.04, 0.08 micrograms/kg/min at 3-minute intervals, and was terminated for any of the following reasons: angina, significant arrhythmia, significant ST segment depression (greater than or equal to 0.1 mV) or target heart rate. Thallium scintigrams were obtained immediately after terminating ISP infusion, and after a 3-hour delay, redistribution scans were obtained. Scintigrams were considered positive when a reversible defect was present. In nine patients who underwent exercise tests, exercise thallium scintigraphy was also performed. After the stress tests, coronary angiography was performed. According to the presence or absence of significant coronary artery stenosis (greater than or equal to 75%), all subjects were divided into two groups: coronary artery disease (CAD) group (n = 12) and so-called normal coronary (NC) group (n = 12). 1. Among 12 patients in the CAD group, ISP induced anginal pain in six (50%), and ISP-ECG and ISP thallium scintigraphy were positive in 10 (83%) and in 11 (92%), compared with four (33%), four (33%) and two (17%) in the NC group.(ABSTRACT TRUNCATED AT 250 WORDS)

[The heart rate alternative sequence during pharmacologic total autonomic blockade in patients with sick sinus syndrome: differential effects in relation to age]

To study the age-related changes of the sinus node function and the variations of influence of autonomic nervous system, pharmacologic total autonomic blockade (TAB) was conducted in 35 patients with symptomatic sinus bradycardia (21 men and 14 women, 50 +/- 21 years, mean +/- SD). Twenty-one patients [Group I, consisting of 14 patients younger than 60 years (group IY) nd 7 patients 60 years or older (group IE)] had a normal intrinsic heart rate (IHRo), and 14 patients had an abnormal IHRo [Group II, consisting of 8 patients younger than 60 years (group IIY) and 5 patients 60 years or older (group IIE)]. The basic cycle length was significantly longer in group II than in group I, suggesting that intrinsic sinus node function was more seriously deteriorated in group II in spite of the compensatory effect of autonomic regulation. In group II it was characteristic that the cycle length (CL) after atropine sulfate administration was longer than the CL of the predicted intrinsic heart rate (IHRp). Otherwise, some group II patients might be regarded as normal by atropine sulfate administration alone. Parasympathetic tone showed a negative correlation with age, and it was most enhanced in group IIY, suggesting that parasympathetic negative chronotropy was stronger in this group. In the course of propranolol administration, prolongation of CL was significantly larger in group IIE than in group IIY, but there was no age-related difference in group I. In group II, beta-adrenergic blockade with propranolol administration showed that sympathetic positive chronotropy was a critical compensatory factor around the upper limit of the CL of IHRp.(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of abnormal systolic blood pressure response during supine ergometer exercise and postexercise in ischemic heart disease, studied by exercise radionuclide ventriculography

The prognostic value of abnormal postexercise systolic blood pressure (BP) response has not been investigated. Therefore, the significance of abnormal BP response during exercise and postexercise was examined in 169 patients with ischemic heart disease subjected to supine ergometer exercise gated equilibrium radionuclide ventriculography, coronary arteriography, and follow up averaging 3.6 years. Abnormal BP response during exercise (exertional "hypotension") was defined as 1) a failure of BP to rise by at least 11 mmHg or 2) an initial rise in BP but subsequent fall by more than 10 mmHg during exercise. Abnormal BP response during postexercise (postexercise "hypertension") was defined as an increase of more than 10 mmHg above the peak exercise BP. Of 169 patients, 51 (30%) had an abnormal BP response. Four types of BP response were identified: exertional "hypotension" (group 1a, n = 11), postexercise "hypertension" (group 1b, n = 30), exertional "hypotension" with postexercise "hypertension" (group 1c, n = 10) and normal BP response (group 2, n = 118). Both average exercise duration and peak heart rate were significantly lower in groups 1a, 1b and 1c than in group 2. The severity of exercise ST-segment depression was greater in groups 1b and 1c than in group 2. However, there was no significant difference in the severity of exercise ST-segment depression between group 1a and group 2. A decline in ejection fraction occurred more frequently in groups 1b and 1c than in group 2. Patients in groups 1a, 1b and 1c had more extensive coronary artery disease (CAD) than did patients in group 2. Medically treated patients with an abnormal BP response (groups 1a, 1b and 1c) had a poorer prognosis than did those with a normal BP response (group 2). These findings suggest that an abnormal BP response during supine exercise is infrequent, but is usually associated with impaired exercise tolerance and severe CAD. An abnormal postexercise BP response is also infrequent, but is more closely associated with evidence of myocardial ischemia and global left ventricular dysfunction than exertional "hypotension". In conclusion, postexercise "hypertension" has the same value as exertional "hypotension" as a predictor of poor prognosis.

Evaluation of myocardial perfusion abnormality by profile analysis for digital subtraction angiogram

For quantitative estimation of ischemia, ECG-synchronized digital subtraction angiography was performed for selective coronary arteriography. The authors obtained sequential myocardial perfusion images at the arterial, capillary, and venous phases. Profile densitometry was performed along the cross section perpendicular to the long axis of the left ventricle to assess regional myocardial perfusion at the capillary phase quantitatively. By this densitometry, the volumes of vascular bed perfused by the left coronary artery could be estimated, and further, nontransmural myocardial infarction could be differentiated from transmural myocardial infarction through the profile of its density curve. This method appears to be useful for the analysis of myocardial perfusion of ischemic heart disease.

Involvement of calcitonin gene-related peptide in the positive chronotropic and inotropic effects of piperine and development of cross-tachyphylaxis between piperine and capsaicin in the isolated rat atria

Piperine as well as capsaicin showed positive chronotropic and inotropic effects in the isolated spontaneously beating right atria and electrically driven left atria of rats, respectively. The responses to piperine were not affected by the presence of the antagonists to norepinephrine, acetylcholine, histamine and serotonin. However, once the tissue was pretreated with piperine or capsaicin, the response to subsequent application of piperine was reduced significantly. Both positive chronotropic and inotropic effects of capsaicin were also attenuated after the tissue was treated with piperine or capsaicin. Thus, not only a tachyphylaxis to either piperine or capsaicin itself but also a cross-tachyphylaxis between piperine and capsaicin developed. Nonadrenergic noncholinergic calcitonin gene-related peptide (CGRP)-like immunoreactive nerves were distributed in the muscle layers of both atria. CGRP-like immunoreactivity was depleted considerably by treatment of the tissue with piperine or capsaicin. When endogenous CGRP was depleted, although the positive chronotropic and inotropic effects of piperine and capsaicin were abolished, the effects of CGRP and isoproterenol were not affected. These results indicate that both piperine and capsaicin cause positive chronotropic and inotropic responses by releasing CGRP from nonadrenergic noncholinergic nerves, and that the development of cross-tachyphylaxis between piperine and capsaicin is due to the depletion of endogenous CGRP.

Effect of nifedipine on left ventricular function during exercise in patients with stable effort angina. Relation of its efficacy to the severity of coronary artery disease

To evaluate whether the effect of nifedipine on left ventricular function relates to the severity of coronary artery disease (CAD) or not, supine graded ergometer exercise testing was performed before and after sublingual administration of 10 mg nifedipine in 24 patients with stable effort angina. To minimize the effect of nifedipine on myocardial oxygen consumption, exercise before and after nifedipine was discontinued at the same target rate pressure product. Percent (%) left ventricular ejection fraction (EF) [EF during exercise/EF at rest.100] was measured before and after nifedipine by radionuclide angiocardiography. The angiographic degree of CAD was defined by Gensini's CAD scoring as follows: severe CAD: greater than or equal to 50, moderate: less than 50 greater than 20 and mild: less than or equal to 20. After nifedipine, left ventricular function (%EF) was improved in all 6 patients with mild CAD, but was worsened in all 9 patients with severe CAD. Maximal ST segment depression during exercise was improved in 5 of 6 patients with mild CAD, while improvement was induced in 5 of 9 patients with moderate CAD and in 3 of 9 patients with severe CAD. Jeopardy of coronary collateral vessels may have an influence on the effect of nifedipine. It is suggested that the effect of nifedipine on left ventricular function is influenced by the severity of CAD when most of its effect on myocardial oxygen consumption is eliminated.

Effects of piperine on calcitonin gene-related peptide (CGRP)-containing nerves in the isolated rat atria

Piperine, a major pungent agent of black peppers, induced both positive chronotropic and inotropic responses in the isolated atria of rats. These responses were not blocked by various antagonists but exhibited rapid tachyphylaxis. After exposure to piperine in vitro, endogenous calcitonin gene-related peptide (CGRP) was profoundly depleted from intracardiac nerves. These results suggest that piperine releases endogenous CGRP from intracardiac non-adrenergic non-cholinergic nerves and that released CGRP exerts positive chronotropic and inotropic effects.

Positive inotropic effects and receptors of calcitonin gene-related peptide (CGRP) in porcine ventricular muscles

Calcitonin gene-related peptide (CGRP) in porcine ventricular muscles. positive inotropic effects in the isolated, electrically driven false tendon of the porcine heart. Specific CGRP-binding sites were present in solubilized membrane fractions; the dissociation constant (Kd) and the maximum binding (Bmax) were 50.4 pM and 180 fmol/mg protein, respectively. SDS-PAGE analysis of CGRP-binding sites revealed the molecular mass of 70 K and 120 K. Few CGRP-like immunoreactive nerves were present in the ventricular muscle layer. These results indicate that CGRP activates specific receptor sites on the ventricular muscles and causes positive inotropic responses. CGRP receptors in ventricles are likely to be activated by circulating CGRP.

Tricuspid regurgitation diagnosed by intravenous digital subtraction angiography

In spite of numerous available diagnostic methods, controversies concerning the precise diagnosis of tricuspid regurgitation (TR) still remain. In right ventriculography, catheter placement may modify tricuspid valvular function. Though noninvasive Doppler echocardiography is a useful method, it is sometimes too sensitive for clinical use. Furthermore, it is not applicable to cases in which ultrasound penetration is limited. In this study, we evaluated TR using intravenous digital subtraction angiography (DSA), which can provide good images even in cases with poorly recorded echocardiograms. For this study, we placed a catheter in the superior vena cava. Cardiac DSA examinations were performed in one hundred and one patients with heart disease. We injected 35 ml of contrast medium at a speed of 18 ml/sec via a catheter introduced in the superior vena cava. DSA images by continuous mode were obtained in the RAO projection for 15-20 sec. Sequential DSA images were observed and analyzed by time-density curves of the regions of interest (ROI) which were placed in the right ventricle (RV) and inferior vena cava (IVC). Doppler echocardiography was performed for 16 cases in which TR was suspected. Of these, phonocardiography with jugular pulse tracing was recorded for 14 and contrast echocardiography were performed for six, respectively. In cases without evidence of TR, regurgitation of contrast medium into the IVC during RV systole was not recorded by the DSA method. In cases of clinically-proven TR, regurgitation into the IVC during RV systole was observed. Thus, this was considered a diagnostic feature of positive TR using the DSA method, and 13 of the 16 cases undergoing Doppler echocardiography were diagnosed as having TR using the DSA method. The severity of TR was categorized as mild, moderate and severe according to analyses of time-density curves. The severity established by the DSA method showed a close correlation with the clinical severity of TR. Doppler echocardiography was negative for TR in two of the 13 cases, but positive for TR in two of the 16 suspected cases only by the Doppler method. In cases of moderate to severe TR diagnosed by the DSA method, jugular pulse tracings showed a regurgitant wave. By contrast echocardiography, TR was evident only in cases of severe TR diagnosed by the DSA method. In conclusion, the DSA method proved useful for diagnosing TR.

Assessment by autonomic blockade of age-related changes of the sinus node function and autonomic regulation in sick sinus syndrome

Age-related changes of the sinus node (SN) function and the autonomic influence on the SN function were evaluated in 65 patients with sick sinus syndrome (range 14 to 84 years). Heart rate (HR), corrected SN recovery time and sinoatrial conduction time were measured before (basic) and after (intrinsic) autonomic blockade (propranolol 0.2 mg/kg plus atropine 0.04 mg/kg intravenously). Percent of autonomic chronotropies of the SN function were calculated by the following formulas: (1)--(intrinsic HR--basic HR/intrinsic HR) X 100; (2) (intrinsic corrected SN recovery time--basic corrected SN recovery time/intrinsic corrected SN recovery time) X 100; (3) (intrinsic sinoatrial conduction time--basic sinoatrial conduction time/intrinsic sinoatrial conduction time) X 100. Basic HR, basic corrected SN recovery time and basic sinoatrial conduction time did not vary with age. Intrinsic HR decreased with age, but this correlation was weak (r = -0.54, p less than 0.001). Intrinsic corrected SN recovery time and intrinsic sinoatrial conduction time tended to increase with age (r = 0.26, p less than 0.05; r = 0.29, p less than 0.05, respectively). Percent chronotropies of HR, corrected SN recovery time and sinoatrial conduction time were negative values in younger patients and positive values in elderly patients; they correlated positively with age (r = 0.59, p less than 0.001; r = 0.60, p less than 0.001; r = 0.43, p less than 0.001, respectively). Thus, the basic SN function did not change with age, while the intrinsic SN function deteriorated with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Classification of hypertrophied hearts in essential hypertension: evaluation by left ventricular wall stress and adrenergic responses

Left ventricular mass, fractional shortening, and end systolic wall stress (mechanical indices) measured by echocardiography and the response of fractional shortening and end systolic wall stress to the infusion of isoproterenol (0.02 microgram/kg/min for 5 min) (a non-mechanical index) were studied in 57 patients (mean (SD) age 49(8)) with essential hypertension. Nineteen patients had subnormal end systolic wall stress (group 1), 25 patients had normal end systolic wall stress and slightly increased left ventricular mass (group 2A), and 13 patients had normal end systolic wall stress and considerably increased left ventricular mass (group 2B). Plasma noradrenaline concentration was higher in group 2B than in the other groups. When end systolic wall stress was greater than 12 g/cm2 this variable showed a significant inverse linear relation with fractional shortening before isoproterenol infusion. The inotropic response to isoproterenol was measured as the increase of fractional shortening corrected for the decrease of end systolic wall stress (delta fractional shortening/--delta end systolic wall stress). The mean (SD) change in delta fractional shortening/--delta end systolic wall stress was significantly larger in group 1 (1.40 (0.60) cm2/g) than in group 2A (0.85 (0.39) cm2/g), and was significantly larger in group 2A than in group 2B (0.56 (0.15) cm2/g). In patients with hypertensive hypertrophy with subnormal end systolic wall stress (inappropriate hypertrophy) the beta adrenergic response is increased; in hypertensive hypertrophy with normal end systolic wall stress (appropriate hypertrophy), however, it is normal, or becomes reduced as plasma noradrenaline increases.

The prognostic significance of left ventricular response to isoproterenol infusion in patients with dilated cardiomyopathy

To evaluate the prognostic value of the left ventricular response to isoproterenol infusion in patients with dilated cardiomyopathy (DCM), 25 patients, 17 men and eight women, were studied. According to responses of left ventricular function to isoproterenol (0.02 microgram/kg/min), the patients were classified in two groups: the normal response group, in which fractional shortening increased by more than 10% (n = 10); and the low response group, in which fractional shortening increased by 10% or less (n = 15). A follow-up spanning four to 40 months with an average of 21 months disclosed that six patients died, two deteriorated, and six had no change in the low response group, while seven patients were improved, three stabilized, and no one deteriorated or died in the normal response group. There was a difference in the clinical courses of the two groups. Thus, the left ventricular response to isoproterenol proved useful in predicting the course of DCM.

Effects of capsaicin on nonadrenergic noncholinergic nerves in the guinea pig atria: role of calcitonin gene-related peptide as cardiac neurotransmitter

Transmural nerve stimulation (TNS) in vitro produced positive chronotropic and inotropic responses in the spontaneously beating right atria and electrically driven left atria of guinea pigs, respectively. Both the positive responses of the atria were mediated not only by adrenergic but also by nonadrenergic noncholinergic (NANC) nerves. Numerous calcitonin gene-related peptide (CGRP)-like immunoreactive nerves were found in the sinus node and the muscle layers of both atria of guinea pigs. Exogenously applied CGRP produced positive chronotropic and inotropic responses in a dose-dependent manner. In both the right and left atria, capsaicin (10(-5) M) induced positive chronotropic and inotropic responses. The second application of capsaicin did not cause any responses in the atria, indicating a rapid development of tachyphylaxis. When the tissues developed tachyphylaxis to capsaicin, the intensity of CGRP-like immunoreactivity greatly decreased in the sinus node and in both atria. In the atria that developed tachyphylaxis to capsaicin, the positive chronotropic and inotropic responses to NANC nerve stimulation diminished markedly, but the responses to exogenous CGRP and those attributed to adrenergic nerves were not affected. These results suggest that CGRP is the neurotransmitter of intracardiac NANC nerves and that capsaicin produces positive chronotropic and inotropic responses through the release of CGRP from NANC nerves in the guinea pig atria. It is also suggested that capsaicin depletes endogenous CGRP, thereby accounting for the rapid development of tachyphylaxis to capsaicin and the marked and selective diminution of TNS-induced NANC responses following application of capsaicin.

Aneurysm of patent ductus arteriosus in an adult case: findings of cardiac catheterization, angiography, and pathology

A 42-year-old male was admitted to our hospital for evaluation of a left precordial continuous murmur. Results of catheterization revealed a step-up of oxygen content in the pulmonary arteries and the calculated left-to-right shunt flow was 40% of the pulmonary arterial flow. Furthermore, aortography unexpectedly revealed an aneurysm of the patent ductus arteriosus. During surgery, the aneurysm was discovered to arise from the frontal wall of the ductus arteriosus, and histological observation showed focal necrosis and mucoid degeneration of the media of the aneurysmal wall in contrast to a thickened intimal fibroelastosis of the adjacent ductal wall. This is presumed to be the first adult case of patent ductal aneurysm ever reported in which antemortem diagnosis and surgical treatment were successfully conducted. Our case may suggest that the fragility of the ductal wall following the structural change in an incomplete closing process is considered as a potential pathogenesis of ductal aneurysm formation.

Effects of nifedipine on left ventricular systolic and diastolic function in patients with ischemic heart disease. Radionuclide angiocardiographic studies at rest and during exercise

The purpose of this study was to evaluate the acute effects of sublingual nifedipine (10 mg) on left ventricular systolic function (ejection fraction, peak ejection rate, time to peak ejection rate) and diastolic function (peak filling rate, time to peak filling rate, filling fraction during rapid filling) at rest and during exercise using radionuclide angiography in 17 patients with ischemic heart disease. The results of the study were as follows. Diastolic indexes in the patient group were significantly different from the values in the control group at rest and during exercise. Peak filling rate and filling fraction improved significantly after nifedipine administration. These values did not show significant differences from the values in normal subjects which were obtained before nifedipine administration. The peak filling rate during exercise after nifedipine administration increased significantly, although the value was lower than that in the control group. At rest, systolic indexes in the patient group showed abnormal values, although the differences from the control values were not significant. Ejection fraction and peak ejection rate were significantly lower than those in the control group during exercise. After nifedipine administration, peak ejection rate at rest and during exercise, and ejection fraction at rest in the patient group improved significantly. Seven of 17 achieved the same exercise workloads as control conditions without symptoms or ECG changes. These data suggest that nifedipine improved left ventricular systolic and diastolic dysfunction, as well as exercise tolerance in patients with ischemic heart disease.

Effects of the rise in aortic pressure on coronary flow reserve in dogs. Comparison between constriction of the descending thoracic aorta and injection of methoxamine

In order to investigate the effect of a rise in aortic pressure on coronary flow reserve and also on the difference of its effect according to the methods used to raise aortic pressure, this experiment was performed. Using 7 anesthetized dogs with heart rate held constant by a pacemaker, both the resting and the peak reactive hyperemic left circumflex coronary flow were measured following raising of the aortic pressure by either descending thoracic aorta constriction or methoxamine injection. The resting and peak reactive hyperemic coronary flows both increased linearly following the rise in aortic pressure. The magnitude of the resting flow increment and the resting coronary vascular resistance following raising aortic pressure did not differ significantly between the two different methods. However, the magnitude of the peak hyperemic flow increment and the peak hyperemic coronary vascular resistance following raising aortic pressure were significantly smaller with methoxamine injection than with aortic constriction. These data indicate that coronary flow reserve increases proportionally with a rise in aortic pressure. However, the magnitude of the increment of coronary flow reserve is smaller following an alpha-adrenoceptor-mediated rise in aortic pressure, because the maximal coronary vasodilation was reduced by alpha-stimulated coronary vasoconstriction.

Impaired left ventricular rapid filling during exercise in patients with hypertrophic cardiomyopathy

The influence of exercise on left ventricular diastolic filling was evaluated in 14 patients with hypertrophic cardiomyopathy (HCM) and 14 normal controls (NC) by dynamic exercise echocardiography. Using X-Y digitizer and computer, normalized peak rate of change of the left ventricular dimension during systole (pVs) and the rapid filling phase (pVd) were determined from the left ventricular echocardiograms at rest and during exercise when heart rate reached 100 beats/min. At rest and during exercise, pVs was significantly higher in HCM (3.2 +/- 0.4/s at rest, 4.3 +/- 1.4/s during exercise) than in NC (2.4 +/- 0.5/s at rest, 3.0 +/- 0.4s during exercise) (p less than 0.001, p less than 0.001, respectively), but pVd in HCM (4.2 +/- 1.0/s at rest, 5.8 +/- 1.0/s during exercise) was not significantly different from that in NC (4.1 +/- 1.0/s at rest, 6.0 +/- 0.7/s during exercise). The ratio of pVd to pVs (pVd/pVs) in HCM did not show significant increment during exercise (1.35 +/- 0.38 to 1.43 +/- 0.35), though that ratio in NC was significantly increased by exercise (1.67 +/- 0.22/s to 1.97 +/- 0.19/s, p less than 0.001). There was no correlation between pVd and the degree of left ventricular hypertrophy. These results suggest that diastolic reserve to exercise is depressed in HCM and that other factors besides left ventricular hypertrophy may account for diastolic abnormality.

Effects of coronary collaterals on regional myocardial function during temporary coronary occlusion and hypoxic coronary perfusion

The effects of coronary collaterals on regional myocardial function during temporary ischemia and hypoxia were studied in 12 open-chest dogs. Using an ultrasonic dimension gauge, systolic segment shortening in the left anterior descending coronary artery (LAD) area was measured at 1 min after the following three experimental conditions: LAD occlusion and LAD hypoxic perfusion with nonoxygenated solutions at two different pressures (60 mmHg and 120 mmHg). Collateral function was assessed by both LAD diastolic retrograde pressure and the percentage of increase in left circumflex coronary flow at 1 min after LAD occlusion. Systolic segment shortening decreased less with hypoxic perfusion than with occlusion, however, this beneficial effect on regional contraction was greater at a perfusion pressure of 60 mmHg than at one of 120 mmHg. The magnitude of decrease of systolic shortening was variable among individual dogs but correlated linearly with each of the two collateral function indexes, not only during occlusion but also during hypoxic perfusion. In conclusion, the preventive effect of hypoxic coronary perfusion on the early decline of regional myocardial function, in comparison to the changes seen during ischemia, may depend on coronary collaterals in addition to its washout effect on metabolites. In order to maintain myocardial function, perfusion pressure should be at an optimal level.

Variable neurohumoral and hemodynamic responses to exercise in patients with exertional angina: influence of the severity of coronary artery disease

To assess neurohumoral and hemodynamic responses to exercise in patients with exertional angina, we measured plasma norepinephrine (NE) concentrations in 23 patients with exertional angina (with no heart failure) and compared the results with their coronary arteriographic findings. The 23 patients were divided into two groups: 14 cases with multiple vessel disease (MVD) and 9 cases with one-vessel disease. At resting state there were no significant differences between the two groups in levels of NE. At maximal exercise there were no significant differences between the groups in increases of heart rate, blood pressure, and rate-pressure product, but exercise-induced increase of plasma NE (%) was significantly larger in MVD (131.6 +/- 95.4%) (mean +/- SD) than in one-vessel disease (69.0 +/- 45.3%) (p less than 0.01). In conclusion, plasma NE responses to exercise differ between patients with multiple vessel disease and patients with one-vessel disease.

Quantitative analysis of left ventricular function by cold pressor two-dimensional echocardiography in patients with coronary artery disease

Quantitative assessment of left ventricular function in patients with coronary artery disease was made by computer analysis of two-dimensional echocardiography performed during a cold pressor test. Short-axis cross-sectional images of the left ventricle at the levels of the mitral valve and chordae tendineae were recorded by a phase array sector scanner in 12 patients with coronary artery disease and 11 normal controls. Endocardial outlines at end-diastole and end-systole were traced and analyzed by a computer system. The short-axis cross-sectional images were divided into octants and were analyzed. The segmental area and its changes during the cardiac cycle were measured and calculated for each octant. Regional function of the left ventricle was evaluated by percent changes of segmental area. The regional segmental area changes in patients with coronary artery disease were compared with those in normal controls. Similar increments were achieved in rate pressure product in the 2 groups. In relation to the perfusing coronary arteries, 8 segments were integrated arbitrarily into 3 walls (anteroseptal wall, lateral wall, and posterior wall and posterior septum). The cold pressor test induced wall motion abnormalities in 12 of 16 walls which were supplied by stenosed coronary arteries. In contrast, wall motion abnormalities were detected in only 5 of 38 walls which were supplied by coronary arteries without significant stenotic lesions. The sensitivity of cold pressor test-induced wall motion abnormalities in detecting coronary artery disease was 75% and the specificity was 87%. No serious complications were encountered in this study. In conclusion, computer-aided cold pressor two-dimensional echocardiography is a safe and sensitive method for the assessment of left ventricular function and diagnosis of coronary artery disease.

Daily variations of ECG and left ventricular parameters at exercise in patients with anginal attacks but normal coronary arteriograms

In 21 patients with typical exercise-induced anginal pain but normal coronary arteriograms (group N) and in 14 patients with angiographically proved coronary stenosis (group C), symptom-limited ergometer exercise ECG and radionuclide angiocardiography were performed twice on two different days. Exercise-induced ST changes showed larger variations between the two exercise tests in group N than in group C ([delta ST1-delta ST2]: 0.07 +/- 0.06 mV in group N, 0.03 +/- 0.03 mV in group C, p less than 0.05). Rate pressure product and left ventricular ejection fraction at exercise also showed larger variations between the two tests in group N than in group C (p less than 0.001, p less than 0.05, respectively). However, substantial overlaps existed in some cases in the two groups. In conclusion, some of the patients with exercise-induced anginal pain but normal coronary arteriograms may have a variable threshold of exertional chest pain probably caused by variation in coronary vascular tone, and the other patients may have a fixed threshold of chest pain caused by other mechanisms.

Reliability of non-invasive estimates of pulmonary hypertension by pulsed Doppler echocardiography

The duration of the acceleration phase of pulmonary systolic flow was measured by pulsed Doppler echocardiography in 39 normal subjects and 67 patients with heart disease to evaluate the reliability of this Doppler index as an estimate of pulmonary arterial pressure. The mean (SD) Doppler index in patients with abnormal mean pulmonary arterial pressure (greater than 15 mm Hg) was significantly shorter than that in normal subjects (110 (30) ms vs 150 (10) ms). The Doppler index was significantly related to the mean pulmonary arterial pressure (r = -0.75) the pulmonary blood flow (r = 0.46), and the total pulmonary vascular resistance (r = -0.68). Forty four of 45 patients with an abnormal index (less than or equal to 120 ms) showed abnormal mean pressure (greater than 15 mm Hg). Without exception patients with a low index (less than or equal to 90 ms) had distinct pulmonary hypertension (greater than or equal to 25 mm Hg). Twelve of 22 patients with a normal index (greater than or equal to 130 ms), however, also showed abnormal pressures. Nine of the 12 had an atrial septal defect and they had high pulmonary arterial pressure associated with high blood flow. Eighteen patients with valvar heart disease, whose mean pulmonary arterial pressure ranged from 16 mm Hg to 24 mm Hg, had a significantly shorter acceleration phase and a higher total vascular resistance than 11 patients with atrial septal defect in whom the pressure range was similar (120(20) ms vs 140 (20) ms, 3.8 (1.1) hybrid resistance unit vs 1.6 (0.5)). Thus although the acceleration time of the pulmonary systolic flow is useful for the evaluation of pulmonary hypertension, it is a complex index that is affected not only by pulmonary arterial pressure but also by pulmonary blood flow and pathological changes in the pulmonary vascular bed.

Isoproterenol infusion stress two-dimensional echocardiography in diagnosis of coronary artery disease in elderly patients. Comparison with the other stress testing methods

Since a dynamic exercise stress test cannot always be performed adequately in elderly patients, an alternative method is needed for evaluation of coronary reserve. We studied two-dimensional echocardiographic (2-DE) and electrocardiographic (ECG) responses to infusion of isoproterenol (ISP) at a rate of 0.02 micrograms/Kg/min in 40 elderly patients with chest pain. The results were compared with exercise ECG (EX-ECG) tests and exercise radionuclide angiocardiography (EX-RNA) in 13 of these patients. No serious complications were encountered in the ISP test. The diagnostic sensitivity for coronary artery disease (CAD) was 71% for ISP-2-DE, 71% for ISP-ECG, 86% for EX-ECG and 71% for EX-RNA. The specificity for CAD was 83% for ISP-2-DE, 33% for ISP-ECG, 50% for EX-ECG and 100% for EX-RNA. In conclusion, the ISP-2-DE test is a safe, easily available and useful method for the assessment of coronary artery disease in elderly patients.

Pregnancy in cardiac patients: possible influence of volume overload by pregnancy on pulmonary circulation

To evaluate the influence of volume overload by pregnancy on heart diseases, the relations between cardiac status before pregnancy and clinical courses during pregnancy were studied, especially from the viewpoint of pulmonary circulation. In 206 pregnant cardiac patients whose prepregnancy laboratory data were known, the deterioration (appearance or advance of heart failure) during pregnancy was prospectively related to: pulmonary congestion (p less than 0.05), enlarged left atrium (p less than 0.05), atrial fibrillation (p less than 0.01) and right ventricular hypertrophy (p less than 0.005) in mitral stenosis; cardiomegaly (p less than 0.05) and atrial fibrillation (p less than 0.005) in mitral regurgitation; cardiomegaly (p less than 0.005) in congenital heart diseases; and to previous congestive heart failure (p less than 0.005) in total cases. All of the cases with systolic pulmonary artery pressure higher than 50 mmHg deteriorated during pregnancy. Some cases with no deteriorating laboratory findings showed dyspnea suddenly at the end of pregnancy. In 1033 cardiac patients who had experienced pregnancy, deterioration during pregnancy was seen more frequently in cases with mitral valvular diseases that in those with aortic valvular diseases. No deterioration was seen in pulmonary stenosis patients. Abnormal status of pulmonary circulation may be one of the important determining factors of deterioration by pregnancy in cardiac patients. The criteria for permitting pregnancy in cardiac patients are proposed.

Digital subtraction angiography: image-sequence analysis for regional myocardial perfusion dynamics

Digital subtraction angiography with selective coronary injections of contrast media has enabled us to obtain clear images, not only of the artery, but of the capillary and venous phases of the myocardial perfusion. In the present study, densitometry was used to estimate regional myocardial perfusion dynamics in 10 control cases and 11 anterior myocardial infarction cases. The time density curve showed that contrast material increased rapidly in the arterial phase and appeared to be washed out monoexponentially in the venous phase. The time from the onset of contrast medium injection to the maximal density of the contrast medium (Tp), and the time constant obtained from the washout curve (Tc) were analyzed. In the control group, Tp in the apical region was slightly prolonged as compared with Tp in the anterobasal region, but the difference was not significant (5.2 +/- 0.5 vs 4.2 +/- 0.4 sec: mean +/- SEM). Tc did not definitely change in any portion of the myocardium (anterobasal 5.1 +/- 0.5, anterior 4.8 +/- 0.5, apex 4.6 +/- 0.5 sec, respectively). In anterior myocardial infarction, Tp in the marginal region was significantly prolonged compared to Tp in the control region (6.0 +/- 0.3 vs 4.7 +/- 0.3 sec, p less than 0.01). Tp was prolonged for more than 10 sec in the infarcted region. Tc in the marginal region was markedly prolonged compared to Tc in the control region (7.4 +/- 0.9 vs 4.4 +/- 0.5 sec, p less than 0.025). Tc could not be determined in the infarcted regions because data acquisition time of our apparatus was inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

[Sigmoid septum causing left ventricular outflow tract obstruction: a case report]

A 67-year-old man with a sigmoid septum causing the left ventricular outflow obstruction by inotropic stimulation was reported. This patient was admitted to the Hospital of the University of Tsukuba because of chest pain. Phonocardiography revealed a systolic ejection murmur which was intensified by amyl nitrite inhalation. A carotid pulse tracing showed a mid-systolic dip and a secondary slow wave during amyl nitrite inhalation. M-mode echocardiography demonstrated neither systolic anterior motion of the mitral valve (SAM) nor mid-systolic closure of the aortic valve at rest. Two-dimensional echocardiography revealed a basal interventricular septum markedly protruding into the left ventricle (sigmoid septum). The remainder of the septum and the left ventricular free wall were not hypertrophied, and no enlargement of the left ventricular cavity was observed. During exercise tests, blood pressure dropped significantly. Cardiac catheterization showed a pressure gradient within the left ventricle with isoproterenol infusion and post-extrasystolic potentiation. These findings suggest that left ventricular outflow tract obstruction could occur in a patient with sigmoid septum by inotropic stimulation, producing a fall of blood pressure during exercise.

Difference in the response to isoproterenol between asymmetric septal hypertrophy and symmetric hypertrophy in patients with hypertrophic cardiomyopathy

The response to isoproterenol was studied in 9 patients with hypertrophic cardiomyopathy (HCM) and asymmetric septal hypertrophy (ASH), 9 patients with HCM and symmetric hypertrophy (SH), and 9 normal controls (NC), using digitized M-mode echocardiography. There was no significant difference in fractional shortening (FS) between ASH and SH, nor between SH and NC before isoproterenol infusion. During isoproterenol infusion, however, FS was significantly greater in ASH (60 +/- 6%) than in SH (53 +/- 7%) and NC (49 +/- 5%) (p less than 0.05, p less than 0.01, respectively), and normalized peak rate of change of left ventricular dimension during systole (pVs) was greater in ASH (7.7 +/- 1.5/s) than in SH (5.2 +/- 0.8/s) and in NC (4.9 +/- 0.8/s) (p less than 0.001, p less than 0.001, respectively). This study shows that the response to isoproterenol of ASH differs from those of SH and of NC and suggests hypersensitivity of the beta-adrenergic receptor system in ASH and the possibility that ASH is a different clinical entity than SH.

Adverse effect of nifedipine on left ventricular obstruction detected by pulsed Doppler echocardiography

The effect of nifedipine on the ejection flow pattern in the left ventricular outflow tract was observed using pulsed Doppler echocardiography in 6 patients with hypertrophic cardiomyopathy. After sublingual administration of nifedipine (10 mg) to 1 patient, the turbulent ejection flow pattern became more marked and increased in duration compared with the initial state. An increase in turbulence in the left ventricular outflow tract may increase the pressure gradient between the left ventricle and the aorta. Nifedipine appeared to have the potential of adverse action on left ventricular outflow obstruction.

Mitral valve prolapse syndrome with coronary artery spasm: a possible cause of recurrent ventricular tachyarrhythmia

A 54-year-old man with mitral valve prolapse syndrome diagnosed by echocardiography complained of anginal pain associated with ventricular tachyarrhythmia. One day he suddenly lost consciousness, and ECG at that time revealed ventricular fibrillation. Thereafter, he developed ST elevation, sporadic premature ventricular contractions, and R on T phenomenon leading to ventricular fibrillation during the attack of anginal pain. His coronary arteriogram was normal. This case implies that coronary artery spasm may be one of the causes of chest pain and ventricular tachyarrhythmias in patients with mitral valve prolapse syndrome.

Significance of ST-segment and T wave changes in the resting electrocardiograms of patients with exertional angina, studied by exercise radionuclide angiocardiograms

In order to investigate the clinical significance of ST-T changes in resting ECG in angina pectoris, symptom-limited ergometer exercise radionuclide angiocardiography with ECG was performed in 60 patients with exertional angina. In those with normal ECG at rest (Group N), left ventricular ejection fraction (EF) did not change during exercise (71 +/- 5% to 71 +/- 6%). In those with only ST change at rest (Group ST) and those with only T change at rest (Group T), EF decreased significantly during exercise (68 +/- 5% to 63 +/- 7%, p less than 0.01; 68 +/- 6% to 61 +/- 7%, p less than 0.001). In those with ST and T changes at rest (Group ST + T), EF was low at rest (58 +/- 11%) and decreased further at exercise (52 +/- 8%, p less than 0.001). In those whose negative or flat T wave became more negative during exercise, EF was low both at rest and at exercise. In conclusion, ST and T changes at rest in patients with exertional angina might suggest a depressed reserve of myocardial function for exercise.