Biomedical subjects

C T Ting

Publications and source records attributed to C T Ting.

At least 55 records · Page 3Linked to original sources

PubMed1996

Tc-99m sestamibi myocardial SPECT in syndrome X.

The authors reviewed the stress Tc-99m MIBI SPECT results and clinical data of 15 patients with syndrome X. The results of exercise EKG and resting left ventricular ejection fraction (LVEF) were compared with the results of Tc-99m MIBI SPECT. Of the 15 patients, 9 (60%) had a normal Tc-99m MIBI SPECT study and 6 (40%) had an abnormal Tc-99m MIBI SPECT. The authors found that 1) an abnormal Tc-99m MIBI SPECT was common in syndrome X, 2) the results of the exercise EKG were not related to perfusion defects on Tc-99m MIBI SPECT, and 3) for patients with an abnormal Tc-99m MIBI SPECT, the incidence of an abnormal resting LVEF and cardiac abnormalities were not higher than in patients with normal Tc-99m MIBI SPECT studies.

Aged↗

PubMed1996

'Reverse redistribution pattern' during myocardial perfusion imaging with 99Tcm-MIBI.

We retrospectively studied 540 consecutive patients with coronary artery disease (CAD) undergoing 99Tcm-methoxy-isobutyl-isonitrile (99Tcm-MIBI) myocardial single photon emission tomography (SPET) to determine the incidence of the 'reverse redistribution pattern' (RRP). RRP is similar to reverse redistribution (RR) in 201Tl myocardial SPET and is defined as the presence of a perfusion defect on the resting cardiac image, rather than on the exercise image. Our results confirmed 30 (5.6%) patients to have RRP, all of whom underwent diagnostic coronary angiography. None of the 30 patients showed RRP in the territory of the left circumflex coronary artery. RRP occurred in the territory of the left anterior descending coronary artery (LAD) in 16 patients, 12 of whom had a normal LAD. Fourteen patients presented with RRP in the territory of the right coronary artery, all of whom had normal coronary arteries. RRP in 99Tcm-MIBI myocardial SPET is less common than RR in 201Tl myocardial SPET and is frequently associated with normal coronary arteries. RRP with 99Tc(m)-MIBI seems to be of little value in the diagnosis of CAD.

Coronary Angiography↗

PubMed1996

Validation of carotid artery tonometry as a means of estimating augmentation index of ascending aortic pressure.

Our objective was to validate a carotid artery tonometry-derived augmentation index as a means to estimate augmentation index (AI) of ascending aortic pressure under various physiological conditions. A total of 66 patients (50 men, 16 women; mean age, 55 years; range, 21 to 78 years; 44 in Taiwan and 22 in the United States) undergoing diagnostic catheterization were studied. Arterial pressure contours were obtained simultaneously from the right common carotid artery by applanation tonometry with an external micromanometer-tipped probe and from the ascending aorta by a micromanometer-tipped catheter at baseline (n = 62), after handgrip (n = 36), or after sublingual nitroglycerin administration (n = 17). The AI (expressed as percentage values) was calculated as the ratio of amplitude of the pressure wave above its systolic shoulder to the total pulse pressure. The carotid AI was consistently lower than the aortic AI, but the two were highly correlated at baseline and after both handgrip and nitroglycerin. Mean +/- SD and correlation coefficients were baseline (14 +/- 16, 28(+) +/- 17, .77), handgrip (18 +/- 19, 32(+) +/- 15, .86), and nitroglycerin (7 +/- 12, 18(+) +/- 13, .52). In addition, after adjusting for age, sex, height, blood pressure, heart rate, and study site, the changes of both AIs from baseline values with handgrip or nitroglycerin were highly associated such that the aortic AI could be approximated from the carotid AI with appropriate regression equations. The high correlations and predictable changes after interventions between the central AI and those estimated from noninvasive carotid tonometry suggest that this technique may have wide applicability for many cardiovascular studies.

Adolescent↗

PubMed1996

Changes in cardiac autonomic activities in patients with syndrome X. A study of spectral analysis of heart rate variability.

The present study was designed to assess cardiac autonomic activities, coronary microvascular function, and their relationship in patients with syndrome X. Control of coronary blood flow is complex, and impaired coronary flow reserve has been attributed as the cause of myocardial ischemia in patients with syndrome X. It is unknown whether cardiac autonomic activities are altered in the presence of coronary microvascular dysfunction in patients with syndrome X. Eighteen patients with syndrome X were studied. Great cardiac vein flow was measured by the thermodilution method and the coronary flow reserve was determined by intravenous dipyridamole (0.56 mg/kg) infusion. Twenty-four-hour ambulatory electrocardiograms were obtained in a drug-free state. Another 14 age- and sex-matched normal subjects served as a control group. The amplitude (in ms) of ultralow (ULF), very-low (VLF), low (LF), and high (HF) frequency bands and total spectra of heart rate variability were measured for twenty-four-hour and every four-hour interval of the day.

Adult↗

PubMed1996

Coronary microvascular dysfunction is associated with ischemic-like electrocardiogram during exercise in patients with anginal chest pain and normal coronary angiograms.

To determine the possible mechanism of the ischemic-like electrocardiogram (ECG) during exercise in the presence of anginal chest pain and normal coronary angiograms, both a treadmill exercise test (TET) and coronary hemodynamic study were prospectively performed in 33 consecutive patients (18 females and 15 males, aged 48 +/- 10 years) with angina of unknown cause. Although baseline characteristics and coronary hemodynamics were similar between patients with (TET+, n = 17) and those without (TET-, n = 16) ischemic-like ECG during TET, effort angina was more frequently seen in the former group (p < 0.01). Compared to TET- patients, TET+ patients had a significantly lower maximum great cardiac vein flow (GCVF, 108.8 +/- 47.0 vs 146.4 +/- 23.4 ml/min, p = 0.007), higher minimum coronary vascular resistance (0.94 +/- 0.41 vs 0.61 +/- 0.09 mmHg/ml/min., p = 0.003), and lower corrected GCVF (GCVF/rate-pressure product, 0.0087 +/- 0.0036 vs 0.0125 +/- 0.0019, p = 0.001) after dipyridamole infusion (0.56 mg/kg for 4 min). Though coronary flow reserve was significantly lower in TET+ than in TET- patients (2.26 +/- 0.59 vs 3.08 +/- 0.48, p = 0.0001), myocardial oxygen consumption and myocardial efficiency (rate-pressure product/myocardial oxygen consumption) were still similar between these two groups after dipyridamole infusion. Thus, coronary microvascular dysfunction rather than altered cardiac metabolism could contribute to effort angina and ischemic-like ECG during exercise in patients with anginal chest pain and normal coronary angiograms.

Adult↗

PubMed1996

Evidence of genetic heterogeneity of hypertrophic cardiomyopathy in eight Chinese patients.

BACKGROUND: The genetic basis causing hypertrophic cardiomyopathy (HCM) was found due to missense mutations in cardiac beta-myosin heavy chain (beta-MHC), cardiac troponin T and alpha-tropomyosin genes in certain affected families. However, most mutations and majority of the affected families were reported to be related to beta-MHC gene. Till now, 20 different missense mutations of beta-MHC gene identified in more than 40 independent families were distributed in exons 8, 9, 13, 14, 15, 16, 19, 20, 21 and 23. Therefore, we chose these 10 exons for screening. METHODS: Eight probands with HCM and 1 normal control were included for screening. 32P-labeled PCR products of these 10 exons of beta-MHC gene were amplified from genomic DNA obtained from peripheral lymphocytes. PCR-DNA single strand conformation polymorphism (PCR-SSCP) analysis was performed using electrophoresis with polyacrylamide gels with and without 10% glycerol. Large amount copies of these 10 exons were also made from genomic DNA with PCR. Detection of sequencing variation of these exons was determined by the direct sequencing method with dideoxy chain termination method and 35S. RESULTS: No abnormal extra bands were noted on PCR-SSCP analysis. Sequencing analysis showed no missense mutation in these probands. CONCLUSIONS: Genetic heterogeneity of HCM is evident in Chinese patients with HCM.

Aged↗

PubMed1996

Effect of quinapril therapy on blood pressure and serotonin change in patients with mild to moderate hypertension.

BACKGROUND: Previous studies have shown that serotonin plays an important role in hypertension because of its vasoconstrictive effect, mediated through serotonergic receptors. Angiotensin-II is a potent vasopressor which facilitates the aggregation of platelets, subsequently releases serotonin. Because quinapril is an angiotensin-converting enzyme inhibitor and could result in a decrease of angiotensin-II, Quinapril was used to treat patients with mild or moderate hypertension in order to observe the change of plasma serotonin. METHODS: Twenty-two patients, (10 males, 12 females, mean age 45 yrs) without other major medical diseases and secondary causes of hypertension, were selected for this study. High performance liquid chromatography (HPLC) with electrochemical detection was used to detect the plasma serotonin. These patients were given placebos for two weeks before the first dose of quinapril (5 mg). Thereafter, the dosage was adjusted according to the response of blood pressure to a desired value (BP < 140/90 mmHg). At about 14:00 hours on the first day, after the patient had rested for an hour and was in a quiet condition, blood was drawn by venipuncture with heparin as anti coagulant; the plasma serotonin concentration was determined for the baseline value. The plasma serotonin level was rechecked eight weeks later. RESULTS: It was found that systolic blood pressure began to decrease significantly two weeks after quinapril therapy, and then reached a constant state. Blood pressure decreased from 174/107 mmHg to 134/87 mmHg. Among these 22 patients, there were 14 (65%) whose blood pressure reduced to a normal range. Plasma serotonin also decreased significantly from 4.69 +/- /3.67 ng/ ml to 2.89 +/-2.64 ng/ml (p < 0.05). According to this data, 15 in 22 patients (68%) had reduction of plasma serotonin. There was little correlation between change in blood pressure and change of plasma serotonin; the correlation co-efficiency is only 0.019. CONCLUSIONS: This study shows that quinapril has an antihypertensive property and serotonin-lowering effect. Since there was no correlation between the change of serotonin and blood pressure, these two actions of quinapril might have been mediated through different mechanisms.

Adult↗

PubMed1996

The effect of thrombolytic therapy on short- and long-term cardiac autonomic activity in patients with acute myocardial infarction.

BACKGROUND: Reduced heart rate variability after acute myocardial infarction is an important risk stratification factor for mortality and life threatening ventricular arrhythmias. In recent years, thrombolytic therapy has revolutionized the therapy of acute myocardial infarction. However, there is little information about the mechanism of the beneficial effect of thrombolysis on cardiovascular mortality. This study was launched to investigate the relationship between thrombolytic therapy and cardiac autonomic activity, and the sequential changes in heart rate variability after acute myocardial infarction. METHODS: From October 1994 to July 1995, all consecutive patients with their first acute myocardial infarction were prospectively enrolled into the study. Patients without contraindication underwent thrombolytic therapy within six hours of the onset of symptoms. Other patients received conventional treatment. Ambulatory electrocardiography (EKG) was recorded on each patient 7, 90 and 180 days after acute myocardial infarction. Heart rate variability in time- and frequency-domain was analyzed. RESULTS: A total of 49 patients, 45 males and 4 females, were included in this study. The short-term heart rate variability (HRV) (seven-day) in the thrombolytic group was significantly higher than in the nonthrombolytic group in SDANN and SDNN. No significant difference in rMSSD, pNN50, LF, HF or LF/HF ratio was found. The location of MI did not influence the short-term HRV following acute myocardial infarction. In patients treated with thrombolytic agent, the follow-up HRV at 90 days and 180 days increased significantly compared to the baseline HRV (seven-day) in SDANN, SDNN, LF and HF bands. For patients without thrombolytic therapy, their follow-up HRV at 90-day and 180-day increased significantly as compared to the baseline HRV (seven-day) in SDANN and SDNN only. After correction of ventricular ejection fraction, the higher short-term (seven day) HRV activities were still present in SDANN and SDNN in patients with thrombolysis as compared to those without. The 90-day and 180-day HRV did not differ between patients with and without thrombolytic agent. Three patients died suddenly during follow-up, and all showed significantly lower values of HRV than the survivors. CONCLUSIONS: The findings of the present study suggest that 1) in patients with uncomplicated AMI, HRV was transiently reduced with progressive improvement within three months after AMI in both those with and without thrombolytic therapy, and 2) patients who had received thrombolytic treatment had more improved HRV early (seven days) after AMI than those who did not. This improvement, independent of the change of left ventricular function, could be associated with the beneficial effect of thrombolytic therapy in patients with AMI.

Adult↗

PubMed1995

Relation between diurnal variation of blood pressure and left ventricular mass in a Chinese population.

In western populations, patients with hypertension who have a nocturnal decrease in blood pressure (BP) may have less left ventricular (LV) hypertrophy and cardiovascular morbidity than those without a diurnal variation in BP. To further examine this association between nocturnal BP reduction and LV mass index, we studied 720 normotensives (< 140/90 mm Hg), 380 borderline hypertensives (140 to 159/90 to 94 mm Hg), and 582 hypertensives (> or = 160/95 mm Hg) from Taiwan and Quemoy island by using 24-hour ambulatory BP monitoring and 2-dimensional echocardiography to obtain LV mass index during a community-based cardiovascular survey. After controlling for age, sex, height, weight, daytime BP, and daytime heart rate, the nocturnal reduction of systolic BP was found to associate weakly with LV mass index, for the whole population (partial correlation coefficient = -0.06, p < 0.05), as well as for the patients with hypertension (partial correlation coefficient = -0.09, p < 0.05), but these associations were eliminated when 24-hour BP and heart rate were accounted for. The average and percent nocturnal decrease of systolic BP (mean +/- SD; mm Hg, [%]) of 3.2 +/- 5.9 (2.7 +/- 4.8%); 3.3 +/- 7.3 (2.4 +/- 5.4%); and 4.6 +/- 9.0 (3.0 +/- 6.1%) in normotensives, borderline hypertensives, and hypertensives, respectively, was smaller than that found in previous studies. Hence, in this large Chinese population, a small nocturnal BP drop was found and it was only weakly associated with LV mass index. These results emphasize the general need for ambulatory BP reference values based on internal controls.

Adult↗

PubMed1995

Thallium-201 myocardial SPET in strictly defined syndrome X.

We reviewed the exercise thallium-201 (201Tl) myocardial single photon emission tomography (SPET) results and clinical data of 28 patients, adhering to a strict definition of syndrome X. All of the patients had a normal resting left ventricular ejection fraction (LVEF) and no cardiac abnormalities. The results of the exercise electrocardiography (ECG) studies were evaluated and compared with the results of 201Tl SPET. Of the 28 patients, only 3 (11%) had a normal 201Tl SPET scan and 25 (89%) had an abnormal 201Tl SPET scan. We found that a normal 201Tl SPET scan was rare when adhering to a strict definition of syndrome X, and the results of exercise ECG did not correlate well with the perfusion defects observed on the 201Tl SPET scan.

Aged↗

PubMed1995

Different effects of fosinopril and atenolol on wave reflections in hypertensive patients.

We conducted this study to compare the effects of fosinopril versus atenolol on peripheral blood pressure, central arterial wave reflection, and left ventricular mass in a group of patients with essential hypertension. We conducted a double-blind, randomized trial of fosinopril and atenolol in 79 hypertensive patients (52 men, 27 women; mean age, 45.8 +/- 8.5 years; range, 30 to 68 years). Carotid pressure waveforms were recorded noninvasively by applanation tonometry with a Millar micromanometer-tipped probe. The extent of wave reflection was estimated by the augmentation index defined as the ratio of the amplitude of pressure wave above its systolic shoulder to the pulse pressure. The augmentation index, left ventricular mass index by two-dimensional echocardiography, and 24-hour ambulatory blood pressures were determined before and after 8 weeks of daily treatment with fosinopril (10 to 20 mg) or atenolol (50 to 100 mg) with or without diuretics and compared with those values in 79 normotensive control subjects. After 8 weeks of treatment, both drugs lowered 24-hour ambulatory peripheral systolic and diastolic pressures into the normal range to a similar extent (fosinopril, -18/-13 mm Hg; atenolol, -23/-17 mm Hg, both P = NS). On the other hand, whereas the elevated augmentation index in hypertensive patients compared with normotensive subjects (16 +/- 11% versus 10 +/- 8%) was completely normalized by fosinopril (-9.3 +/- 9.8%, P < or = .002), it was lowered by atenolol (-4.8 +/- 8.9%, P < .002) but to a significantly smaller extent (fosinopril versus atenolol effect, P = .04).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Arterial hemodynamics in human hypertension. Effects of the calcium channel antagonist nifedipine.

Previous studies have shown some distinct hemodynamic alterations in essential hypertension, including increased resistance, wave reflections, and pulse wave velocity and decreased arterial compliance. These abnormalities are completely normalized by nonspecific smooth muscle dilation with nitroprusside but not by combined alpha- and beta-adrenergic blockade or angiotensin-converting enzyme inhibition, suggesting an enhanced smooth muscle tone that cannot be attributed solely to the sympathetic nervous or renin-angiotensin systems. Since hypertensive patients have an enhanced calcium influx-dependent vasoconstriction, we performed the present study to examine the extent to which the dihydropyridine calcium channel antagonist nifedipine could normalize the hemodynamic abnormalities in essential hypertension. An essential hypertensive patient group was compared with a normotensive group similar in age, body size, and proportion of men and women. During diagnostic cardiac catheterization, ascending aortic micromanometer pressures and electromagnetic flows were measured at baseline and after sufficient sublingual nifedipine (mean, 24 mg) to normalize blood pressure. From the pressures and flows, aortic input impedance, wave reflection magnitude, and compliance were computed. In the hypertensive group, the hemodynamic alterations were indistinguishable from those summarized above. Nifedipine produced sufficient vasodilation to completely normalize all of these hemodynamic alterations, including wave reflections. From these results, together with those reported in our previous studies, it is clear that the various classes of antihypertensive agents affect hemodynamics differently. All are capable of decreasing blood pressure to normotensive levels, but only nitroprusside and nifedipine can also completely normalize all the other pulsatile hemodynamic alterations. Thus, these hemodynamic effects of the different classes of antihypertensive agents should be considered in choosing a therapeutic modality.

Adult↗

PubMed1995

Short- and long-term effects of antihypertensive drugs on arterial reflections, compliance, and impedance.

This article reviews our work on the effects of different classes of antihypertensive agents on the hemodynamic alterations in essential human hypertension. Short-term studies were done during cardiac catheterization in young normotensive subjects (mean age, 33 years; range, 19 to 40) and several different age-matched (range, 25 to 53 years) groups of patients with essential hypertension. Aortic impedance, resistance, wave reflections, and compliance were calculated from high-fidelity recordings of ascending aortic pressure and flow signals during baseline and after nitroprusside, propranolol followed by phentolamine, phentolamine, captopril, and nifedipine, respectively, at doses sufficient to normalize blood pressure in each hypertensive group. Propranolol exacerbated all the hemodynamic parameters; these effects were only partially overcome by phentolamine. Among the other agents only phentolamine did not completely normalize compliance, and only captopril did not completely normalize wave reflections. The long-term study was a randomized, double-blind comparison of fosinopril and atenolol in 79 normotensive subjects and 79 essential hypertensive patients. Baseline 24-hour ambulatory blood pressures and carotid artery tonometry to index wave reflections were performed in all subjects and in hypertensive patients after 8 weeks of therapy. Both fosinopril and atenolol normalized blood pressure and lowered the elevated augmentation index, but fosinopril had a significantly larger effect than atenolol. Both short- and long-term beta-blockade did not have as beneficial an effect as the other agents. Thus, the differing hemodynamic effects of the various classes of antihypertensive agents might be a consideration in the choice of therapy.

Adult↗

PubMed1995

Short-term and long-term effects of benazepril in mild to moderate hypertensives.

BACKGROUND: Benazepril hydrochloride is a non-sulfhydryl-containing, angiotensin-converting enzyme (ACE) inhibitor. The short-term and long-term antihypertensive effects of benazepril remain to be established in Chinese. METHODS: Hypertensive subjects with diastolic blood pressure 95-110 mmHg, after two week placebo run-in first, entered a four-week double-blind phase with treatment of benazepril 10 mg once daily or captopril 25 mg three times daily, then received one-year open treatment of benazepril 10 mg daily with or without diuretics. Ambulatory blood pressure monitoring was performed at the end of placebo run-in, after four-week double-blind phase, and after one-year open treatment. RESULTS: Of the 75 subjects (41 male, 34 female, mean age 57 +/- 12 years, range 34-88 years) who completed the double-blind phase, 42 subjects finished the one-year extension phase. Reasons for withdrawal from the study included irritable cough (16, 21%), hypotension (1, 1%), and poor compliance (16, 21%). During the short-term double-blind phase, benazepril reduced clinic and mean 24-h ambulatory blood pressure by -21/-10 mmHg and by -17/-10 mmHg respectively, and captopril by -21/-13 mmHg and by -17/-10 mmHg respectively. After one-year open treatment by benazepril for the 42 subjects, the one-year average clinic blood pressure was 134/88 mmHg (155/104 mmHg at entry and 135/93 mmHg at the end of the double-blind phase), and the mean 24-h ambulatory blood pressure was 137/87 mmHg (149/95 mmHg at entry and 132/84 mmHg at the end of the double-blind phase). CONCLUSIONS: The antihypertensive effect of benazepril 10 mg daily with or without diuretics is not significantly different from that of captopril 75 mg daily in the short-term and can reasonably be maintained for one year.

Adult↗

PubMed1995

Use of a low profile Doppler angioplasty guidewire to evaluate the effect of percutaneous coronary angioplasty on coronary artery flow velocity.

BACKGROUND: The intracoronary Doppler flow velocity measurement is widely used. The Doppler flow catheter, used in many studies, still cannot always measure distal portions of coronary artery stenosis. However, three years ago, a low profile Doppler angioplasty guide wire (0.018-inch) was started by apply for measurement of changes in proximal and distal flow velocity during coronary angioplasty. METHODS: Blood flow velocity and diastolic/systolic velocity ratio (DSVR) on both proximal and distal portions of the coronary artery were measured with a low profile Doppler angioplasty guide wire in 13 patients with stenosis of the left anterior descending artery (LAD) during coronary angioplasty. RESULTS: Non-significant improvement in maximal peak velocity was noted in the distal portion of the coronary artery immediately after angioplasty (before, 36 +/- 12 cm/s; after, 41 +/- 12 cm/s; p > 0.05); but significant improvement was found after removal of the balloon (from 41 +/- 12 cm/s to 49.5 +/- 15 cm/s, p < 0.01). Increases in proximal maximal peak velocity after angioplasty were less remarkable (before, 38.5 +/- 15 cm/s; after, 45 +/- 13 cm/s; p > 0.05), and there was a significant increase of DSVR on the distal portion of the left anterior descending artery after angioplasty (before, 2.18 +/- 0.51; after, 2.98 +/- 0.44; p < 0.05). However, there was no significant increase of DSVR on the proximal portion of LAD (before, 2.19 +/- 0.16; after, 2.44 +/- 0.1; p > 0.05). The coronary flow reserve ratio showed no significant increase on the distal portion of the LAD (before, 1.03 +/- 0.3; after, 1.02 +/- 0.3) and proximal portion of LAD (before, 1.05 +/- 0.2; after, 1.03 +/- 0.3). CONCLUSIONS: Increase in peak velocity and DSVR of the distal portion of the coronary artery after angioplasty was more significant after removal of the balloon catheter than as if it were assessed immediately, without removing the balloon catheter. No significant increase in flow velocity of the proximal portion of the coronary artery after angioplasty was observed. No significant increase of the coronary flow reserve of the distal and proximal portion of the coronary artery occurred after successful angioplasty.

Adult↗

PubMed1995

Does coronary artery disease with stressed myocardial ischemia alter heart rate variability?

BACKGROUND: Research has shown that decreased heart rate variability (HRV) is independently associated with increased mortality after acute myocardial infarction. However, the relationship between HRV and myocardial ischemia still remains controversial. The purposes of this study were (1) to determine the relationship between HRV and atherosclerosis of the coronary artery; and (2) to determine the relationship between HRV and the extent of coronary stenosis in patients with stressed myocardial ischemia. METHODS: Forty-six patients, 41 males and 5 females, were included in this study. Ages ranged from 50 years to 79 years. Seventeen volunteers served as the control group, which was comprised of 15 males and 2 females of ages ranging from 40 years to 74 years. For each patient a left ventriculogram and a coronary angiogram were performed. According to their coronary angiograms, patients were divided into normal coronary artery group, atherosclerotic coronary artery group and significant coronary artery disease group. An ambulatory EKG was performed on each patient and volunteer. Heart rate variability was defined as SDNN, SDANN, rMSSD, and pNN50 in time domain measures; and low and high frequency in frequency domain measures. RESULTS: There were no significant differences in all variables of heart rate variability between the atherosclerotic coronary artery group and normal coronary artery group. In addition, there were no significant differences in all variables between the significant coronary artery disease group and the control group or between the significant coronary artery disease group and the normal coronary artery group. CONCLUSIONS: These studies have shown that atherosclerotic or significant coronary artery disease with stressed myocardial ischemia does not impair 24-hour heart rate variability.

Aged↗

PubMed1995

Measurements of heart rate variability in patients with unexplained syncope.

BACKGROUND: Syncope is a common clinical issue with complex and heterogenous etiologies. Research has shown a large proportion of syncope remained unexplained, even after serial investigations. Head-up tilt test with or without isoproterenol infusion could elicit a recurrence in most patients with unexplained syncope. Therefore, autonomically neural-mediated bradycardia and hypotension have been cited as the mainstays of the mechanism. Since the autonomic function can be reflected by heart rate rariability, this study proposed to determine 24-hour heart rate variability in patients with unexplained syncope. METHODS: Fifteen patients, 14 males and 1 female, who were defined as showing symptoms of unexplained syncope, were the subjects of this study. Their ages ranged from 38 years to 79 years. Seventeen healthy volunteers matching in age and sex served as the control group. For each patient and volunteer, 24-hour ambulatory electrocardiographic monitoring was done. Heart rate variability was defined as SDNN index, SDNN, SDANN, rMSSD, and pNN50 in time domain measures; and low, high, and total frequency in frequency domain measures. RESULTS: There was a significantly lower value at low frequency, high frequency, total frequency, rMSSD, and pNN50 in the syncope group than in the control group (p < 0.05). There was no significant difference in SDNN, SDNN index, SDANN and LF/HF ratio between these two groups. CONCLUSIONS: Patients with unexplained syncope had autonomic withdrawal; this was the case either in both sympathetic and parasympathetic components without changing the sympatho-vagal balance, or in purely parasympathetic component.

Adult↗

PubMed1995

Left atrial appendage flow velocity and spontaneous echo contrast in patients with rheumatic mitral stenosis: a multiplane transesophageal echocardiographic study.

BACKGROUND: Left atrial spontaneous echo contrast (LASEC), a putative marker of thrombo-embolic risk, is commonly located in the left atrial appendage (LAA). The aims of this work were to evaluate, using multiplane transesophageal echography, the echocardiographic determinants, specifically LAA outflow Doppler velocity, in the presence of SEC in patients with rheumatic MS. METHODS: Transthoracic and transesophageal echocardiographic tests were performed on 61 patients. The patients were divided into 3 groups based on the presence and type of valvular disease. Patients in group I (n = 28) presented with rheumatic mitral stenosis (MS). Patients in group II (n = 18) presented with valvular heart disease other than MS, and patients in group III (n = 15) had no history of valvular heart disease. The left atrium and appendage were examined for the presence of spontaneous echocontrast and thrombus, using multiplane echo scopy with transducer rotation. Minimal and maximal appendage areas were measured, on a computer-assisted bablet, by tracing a line from the top of the limbus of the left upper pulmonary vein to the appendage endocardial border. The LAA ejection fraction was calculated according to the formula: (maximal area-minimal area)/maximal area. Mitral valvular condition was evaluated with transthoracic and transesophageal echocardiography. Left atrial appendage blood flow velocity profiles were obtained with pulsed-wave Doppler at the orifice of the LAA. RESULTS: LASEC was present in 18 of 28 patients with mitral stenosis (64.3%). Patients with LASEC showed a greater incidence of atrial fibrillation (14/18 vs 12/43, p < 0.005), larger LAD (53.67 +/- 8.74 vs 40.54 +/- 14.85, p < 0.005), smaller LAAEF (38.7 +/- 1.53 vs 69.5 +/- 24.0, p < 0.05), smaller LAAMEV (20.28 +/- 10.07 vs 2.95 +/- 25.11, p < 0.005) and smaller LAAMFV (24.6 +/- 12.23 vs 36.00 +/- 11.01, p < 0.01), when compared with patients without LASEC. For group I, LAAEF, LAAMEV and LAAFV were smaller in patients with SEC than in patients without SEC (p < 0.005, p < 0.05, p < 0.01). However LAD values were similar for patients with and without SEC (53.67 +/- 8.75 vs 54.20 +/- 18.81, p = NS). Both LAAMEV and LAAMFV were related to SEC in patients with atrial fibrillation. However, LAD did not show the same trend. CONCLUSIONS: LASEC is more commonly observed in patients with rheumatic mitral stenosis or atrial fibrillation. Both LAAMEV and LAAMFV are associated with SEC in these patients.

Adult↗