Effect of isosorbide dinitrate (sorbonit) on the exercise reaction in patients with coronary disease and in healthy individuals

The study aimed at evaluating an effect of a single dose of isosorbide dinitrate (Sorbonit) on the exercise reaction in the patients with coronary disease of various degree and in healthy individuals. The study involved 20 male patients of mean age 54.0 +/- 4.5 years with history of myocardial infarction and 12 healthy males of mean age 45.6 +/- 5.0 years. Ergometric test has been performed twice: prior to and 15 minutes after sublingual administration of isosorbide dinitrate in the dose of 10-15 mg. The first test has been interrupted when horizontal ST load exceeded 1 mm or contractions rate was 60% of the maximum value. Similar loads have been used after the administration of Sorbonit. The following parameters have been evaluated: heart rate (HR), systolic blood pressure (BPS), HR x BPS, lactate level (LA), and cardiac index. The value of the load has been measured with the aid of oxygen consumption (VO2). Significant depression of ST segment (less than 3 mm) in the exercise ECG has been noted in 8 patients following isosorbide dinitrate. Exercise tolerance has increased in these patients - CI increased during exercise following drug administration (VO2 the same as prior to the drug administration), and VO2/CI has became closer - physiological.     

Reciprocal change in ST segment in acute myocardial infarction: correlation with findings on exercise electrocardiography and coronary angiography.

The clinical relevance of reciprocal changes in the ST segment occurring at the time of acute myocardial infarction was studied prospectively in 85 consecutive uncomplicated cases. Reciprocal depression of the ST segment was defined as depression of 1 mm or more in electrocardiogram leads other than those reflecting the infarct. All patients underwent maximal, symptom limited treadmill stress testing two weeks after the infarct and coronary angiography six weeks after infarction. Forty six patients had inferior, 34 anterior, and five true posterior infarction. Of the 51 patients with reciprocal changes, 45 (88%) developed exercise induced ST segment depression in areas remote from the infarction zone. At angiography all 45 patients were shown to have stenoses greater than 70% in at least two major vessels. Four patients had negative exercise electrocardiograms and were sequently shown to have single vessel disease subtending their infarct, and the remaining two patients had a false negative treadmill test result. Of the 27 patients without reciprocal changes, 21 (78%) had negative treadmill stress test results associated with single vessel coronary disease. Five had positive stress test results and multivessel coronary disease, and one had a false negative stress test result. The remaining seven patients had ST segment elevation without Q wave formation in the reciprocal areas and were assessed separately. Of these, six had positive stress test results and multivessel coronary disease and one had a negative stress test result and single vessel coronary disease to the infarct area. Twenty one patients with anterior infarcts (62%) and 27 with inferior infarcts (59%) had reciprocal changes. No differences emerged in the relation between infarct site, reciprocal change, and presence of additional coronary disease. At follow up of the 51 patients with reciprocal changes in the ST segment 36 had become symptomatic, of whom 29 had undergone coronary artery bypass surgery. By contrast, only four of the 27 patients without reciprocal changes in the ST segment had developed symptoms, and two of these had undergone coronary revascularisation. Reciprocal ST segment depression at the time of acute myocardial infarction may identify patients with severe coronary disease who are at risk of subsequent cardiac events and appears to be as reliable as results of early postinfarction treadmill stress testing in predicting the underlying coronary anatomy. When the electrocardiogram does not show reciprocal changes treadmill testing provides valuable additional information.     

Pronounced HR variability after exercise in inferior ischemia: evidence that the cardioinhibitory vagal reflex is invoked by exercise-induced inferior ischemia

Potent cardioinhibitory vagal reflex resulting in bradycardia and hypotension has been observed under particular conditions of transmural inferior ischemia and its reperfusion, such as those observed with acute infarction. However, whether exercise-induced ischemia with ST depressions that is subendocardial and that might be recurrently experienced in daily activities can evoke this reflex remains unknown. In patients with exercise-induced ST depressions due to either inferior [right coronary artery stenosis (RCA), n = 52] or anterior ischemia [left anterior descending artery stenosis (LAD), n = 51], we evaluated post exercise vagal activity (from 0 to 6 min) by the time constant of heart rate (HR) decay and HR variability by 30-s averages of the absolute values of successive RR interval differences (DeltaRR). Exercise parameters were similar between groups. The time constant was slightly but significantly shorter in RCA than LAD patients (79 +/- 24 vs. 93 +/- 29 s, P < 0.01). More significantly, DeltaRR early after exercise (0.5-2.5 min) was approximately twofold greater in RCA than LAD patients (from +76 to +118%, P < 0.001), indicating pronounced vagal activity stimulated by inferior ischemia. Revascularization prolonged the time constant (P < 0.05) and attenuated recovery DeltaRR in RCA patients (P < 0.05, n = 10) but did not change both parameters in LAD patients (n = 12). As well as acute inferior infarction, exercise-induced inferior subendocardial ischemia, which might recurrently occur in daily activities, activates the cardioinhibitory reflex. These new findings must be taken into account in interpreting vagal activity in patients with coronary artery disease.     

心电图ST段不同改变与急性心肌梗死患者冠脉造影病变特点及生活质量的相关性研究

目的:探讨心电图ST段不同改变与急性心肌梗死患者冠脉造影病变特点及生活质量的相关性。方法:选取选取2015年6月到2017年6月在本院接受治疗的急性心肌梗死患者208例,根据心电图ST段的改变情况将患者分为ST段抬高组(124例)、ST段压低组(64例)、ST段无偏移组(20例),所有患者进行冠脉造影检查和常规治疗,比较治疗前三组患者的冠脉造影情况和冠脉狭窄程度,比较治疗1个月后三组患者的生活质量评分。结果:在ST段抬高组中,共检测出单支血管闭塞病变99例,占79.84%,两支或两支以上血管病变25例,占20.16%,其中侧支循环开放19例,开放率为15.32%。在ST段压低组中,共检测出单支血管非闭塞病变6例,占9.38%,两支或两支以上血管非闭塞病变56例,占87.50%,单支血管闭塞病变2例,占3.13%,其中侧支循环开放34例,开放率为53.13%。在ST段无偏移组中,单支血管闭塞病变15例,占75.00%,单支或多支血管非闭塞病变5例,占25.00%,其中侧支循环开放7例,开放率为35.00%。ST段抬高组、ST段无偏移组患者的冠脉狭窄程度以重度狭窄为主,ST段压低组患者的冠脉狭窄程度以中度狭窄为主,三组患者的轻度狭窄、中度狭窄、重度狭窄整体比较存在统计学差异(P0.05)。三组患者的疼痛评分、躯体受限评分、精神及活动评分整体比较具有统计学差异(P0.05),ST段压低组的上述评分均显著高于ST段抬高组和ST段无偏移组(P0.05)。结论:心电图ST段不同改变与急性心肌梗死患者冠脉造影病变密切相关,且ST段压低患者的预后通常较好。     

Arterial baroreflex control of heart rate during exercise in postural tachycardia syndrome.

Patients with postural tachycardia syndrome (POTS) have excessive tachycardia without hypotension during orthostasis as well as exercise. We tested the hypothesis that excessive tachycardia during exercise in POTS is not related to abnormal baroreflex control of heart rate (HR). Patients (n = 13) and healthy controls (n = 10) performed graded cycle exercise at 25, 50, and 75 W in both supine and upright positions while arterial pressure (arterial catheter) and HR (ECG) were measured. Baroreflex sensitivity of HR was assessed by bolus intravenous infusion of phenylephrine at each workload. In both positions, HR was higher in the patients than the controls during exercise. Supine baroreflex sensitivity (HR/systolic pressure) in POTS patients was -1.3 +/- 0.1 beats.min(-1).mmHg(-1) at rest and decreased to -0.6 +/- 0.1 beats.min(-1).mmHg(-1) during 75-W exercise, neither significantly different from the controls (P > 0.6). In the upright position, baroreflex sensitivity in POTS patients at rest (-1.4 +/- 0.1 beats.min(-1).mmHg(-1)) was higher than the controls (-1.0 +/- 0.1 beats.min(-1).mmHg(-1)) (P < 0.05), and it decreased to -0.1 +/- 0.04 beats.min(-1).mmHg(-1) during 75-W exercise, lower than the controls (-0.3 +/- 0.09 beats.min(-1).mmHg(-1)) (P < 0.05). The reduced arterial baroreflex sensitivity of HR during upright exercise was accompanied by greater fluctuations in systolic and pulse pressure in the patients than in the controls with 56 and 90% higher coefficient of variations, respectively (P < 0.01). However, when baroreflex control of HR was corrected for differences in HR, it was similar between the patients and controls during upright exercise. These results suggest that the tachycardia during exercise in POTS was not due to abnormal baroreflex control of HR.     

Reduced stroke volume during exercise in postural tachycardia syndrome.

Postural tachycardia syndrome (POTS) is characterized by excessive tachycardia without hypotension during orthostasis. Most POTS patients also report exercise intolerance. To assess cardiovascular regulation during exercise in POTS, patients (n = 13) and healthy controls (n = 10) performed graded cycle exercise at 25, 50, and 75 W in both supine and upright positions while arterial pressure (arterial catheter), heart rate (HR; measured by ECG), and cardiac output (open-circuit acetylene breathing) were measured. In both positions, mean arterial pressure, cardiac output, and total peripheral resistance at rest and during exercise were similar in patients and controls (P > 0.05). However, supine stroke volume (SV) tended to be lower in the patients than controls at rest (99 +/- 5 vs. 110 +/- 9 ml) and during 75-W exercise (97 +/- 5 vs. 111 +/- 7 ml) (P = 0.07), and HR was higher in the patients than controls at rest (76 +/- 3 vs. 62 +/- 4 beats/min) and during 75-W exercise (127 +/- 3 vs. 114 +/- 5 beats/min) (both P < 0.01). Upright SV was significantly lower in the patients than controls at rest (57 +/- 3 vs. 81 +/- 6 ml) and during 75-W exercise (70 +/- 4 vs. 94 +/- 6 ml) (both P < 0.01), and HR was much higher in the patients than controls at rest (103 +/- 3 vs. 81 +/- 4 beats/min) and during 75-W exercise (164 +/- 3 vs. 131 +/- 7 beats/min) (both P < 0.001). The change (upright - supine) in SV was inversely correlated with the change in HR for all participants at rest (R(2) = 0.32), at 25 W (R(2) = 0.49), 50 W (R(2) = 0.60), and 75 W (R(2) = 0.32) (P < 0.01). These results suggest that greater elevation in HR in POTS patients during exercise, especially while upright, was secondary to reduced SV and associated with exercise intolerance.     

Early exercise testing after treatment with thrombolytic drugs for acute myocardial infarction: importance of reciprocal ST segment depression.

OBJECTIVE--To investigate the clinical importance of reciprocal ST depression induced by exercise testing early after acute myocardial infarction in patients treated with thrombolysis. DESIGN--Prospective observational study. SETTING--District general hospital in London. SUBJECTS--202 patients (170 men) aged 33-69 with acute myocardial infarction treated with thrombolysis. MAIN OUTCOME MEASURES--All patients underwent exercise testing and coronary arteriography. ST depression induced by exercise was classified as either reciprocal (associated with ST elevation) or isolated (occurring on its own). The relation between reciprocal ST depression and the following end points was studied: characteristics of the infarct, left ventricular ejection fraction, extent of coronary artery disease on arteriography, and presence of angina induced by exercise. RESULTS--Reciprocal ST depression occurred almost exclusively in Q wave infarctions and was associated with a lower overall ejection fraction than isolated ST depression. It tended to be associated with persistent occlusion of the coronary artery related to the infarct and did not indicate remote ischaemia due to multivessel coronary disease. Unlike isolated ST depression, reciprocal ST depression was not associated with angina induced by exercise. CONCLUSIONS--Reciprocal ST depression induced by exercise is usually associated with extensive Q wave infarctions and persistent occlusion of the artery related to the infarct. It does not seem to indicate reversible ischaemia and should not be used as a non-invasive marker of multivessel disease in the assessment of requirements for further investigation soon after acute myocardial infarction.     

Role of exercise testing early after myocardial infarction in identifying candidates for coronary surgery.

It has been suggested that ST depression in lead V5 or equivalent on early exercise testing after acute myocardial infarction predicts a high risk of death. To evaluate exercise testing and radionuclide ventriculography in this context 103 consecutive patients with myocardial infarction who were able to undertake a limited exercise test before discharge from hospital were exercised and underwent gated blood pool scanning. No serious complications resulted from exercise testing. Twenty nine patients developed ST depression in lead V5, 19 had exertional hypotension, 31 developed a heart rate of greater than or equal to 130 beats/min, and 15 had complex ventricular arrhythmias. Death during the first year after discharge from hospital was associated with exertional hypotension (p less than 0.001) and a heart rate on exercise testing of greater than or equal to 130 beats/min (p less than 0.05); these two variables identified all nine deaths. Inability to complete the exercise protocol for any reason was also predictive of death (p less than 0.01). Ventricular arrhythmias and ST depression in lead V5 induced by exercise were not significantly associated with an increased risk of death. The mean (SD) radionuclide ejection fraction in the patients who died was 29 (16%) compared with 43 (11)% in the patients who survived (p less than 0.001). ST changes on exercise testing after myocardial infarction appear to be less predictive of later complications than haemodynamic signs, which may indicate left ventricular damage rather than ischaemia.     

Skin testing versus radioallergosorbent testing for indoor allergens

BACKGROUND: Skin testing (ST) is the most common screening method for allergy evaluation. Measurement of serum specific IgE is also commonly used, but less so by allergists than by other practitioners. The sensitivity and specificity of these testing methods may vary by type of causative allergen and type of allergic manifestation. We compared ST reactivity with serum specific IgE antibodies to common indoor allergens in patients with respiratory allergies. METHODS: 118 patients (3 mo-58 yr, mean 12 yr) with allergic rhinitis and/or bronchial asthma had percutaneous skin testing (PST) supplemented by intradermal testing (ID) with those allergens suspected by history but showed negative PST. The sera were tested blindly for specific IgE antibodies by the radioallergosorbent test (Phadebas RAST). The allergens were D. farinae (118), cockroach (60), cat epithelium (90), and dog epidermal (90). Test results were scored 0-4; ST >/= 2 + and RAST >/= 1 + were considered positive. RESULTS: The two tests were in agreement (i.e., either both positive or both negative) in 52.2% (dog epidermal) to 62.2% (cat epithelium). When RAST was positive, ST was positive in 80% (dog epidermal) to 100% (cockroach mix). When ST was positive, RAST was positive in 16.3% (dog epidermal) to 50.0% (D. farinae). When RAST was negative, ST was positive in 48.5% (cat epithelium) to 69.6% (D. farinae). When ST was negative, RAST was positive in 0% (cockroach) to 5.6% (cat epithelium). The scores of ST and RAST showed weak to moderate correlation (r = 0.24 to 0.54). Regardless of history of symptoms on exposure, ST was superior to RAST in detecting sensitization to cat epithelium and dog epidermal. CONCLUSION: For all four indoor allergens tested, ST was more sensitive than RAST. When both tests were positive, their scores showed poor correlation. Sensitizations to cat epithelium and dog epidermal are common, even in subjects who claimed no direct exposure.     

The Diagnostic Value of Treadmill Exercise Test Parameters for Coronary Artery Disease

The aim of this study was to determine the diagnostic value of treadmill exercise test (TET) in patients with coronary heart disease (CHD) by comparing the diagnostic conclusions with coronary angiography (CAG). Patients (445) with CHD and suspected CHD underwent TET and CAG, and the corresponding diagnostic conclusions were compared. (1) Out of the 200 cases that had the positive result with TET, 150 cases had been diagnosed CHD by means of CAG; Out of the 245 cases that had the negative result during TET, only 39 cases had been diagnosed CHD by means of CAG. The sensitivity, specificity, positive predictive value, negative predictive value, the false positive incidence, the false negative incidence, and agreement rate in diagnosis of CHD by TET were 79.36, 80.40, 75.00, 84.08, 25.00, 15.92, and 80.00 %, respectively. The patients with multi-vessel disease had a higher positive rate of TET as compared with those with single-vessel disease (P < 0.05). (2) The parameters for 189 cases positive CAG (patients diagnosed CHD by CAG) and 256 cases negative CAG (the control group), including the general exercise time, peak heart rate, and the beginning time of ST depression, were lower than that of control group (P < 0.05). However, the extent of ST depression and duration of ST depression were higher in these patients than in the control group (P < 0.05). (3) 189 cases positive CAG, include 87 cases of single coronary artery and 102 cases of binary or more coronary arteries (the control group). The parameters, including the general exercise time, peak heart rate, and the beginning time of ST depression, were lower than the control group (P < 0.05). However, the extent of ST depression and duration of ST depression were higher in these patients than the control group (P < 0.05). The TET is valuable for noninvasive diagnosis of CHD, especially for patients with multi-vessel disease.     

Value of measuring end tidal partial pressure of carbon dioxide as an adjunct to treadmill exercise testing

The end tidal partial pressure of carbon dioxide (Pco₂) was measured during treadmill exercise in 30 normal controls and 113 patients referred for assessment of chest pain. Among the 92 patients without significant ST depression hypocapnia occurred more often in those reporting “typical” than “atypical” chest pain (17 of 22 patients compared with 29 of 70; p<0·01). Hypocapnia was uncommon in patients with significant ST depression whether reporting typical or atypical chest pain (one of 10 patients and two of 11, respectively).Hypocapnia at rest (Pco₂ <4 kPa) occurred in 16 (14%) patients but in only one control. Hypocapnia occurred during or after exercise in only one control and three of the 21 patients with significant ST depression on exercise (group 1). The remaining 92 patients were divided into those with a history suggestive of hyperventilation (group 2; n=30) and those without (group 3; n=62). Hypocapnia developed significantly more often in both these groups (21 and 25 patients respectively) than in controls or patients with significant ST depression.An abnormal response of the Pco₂ to exercise provided objective data to support a clinical suspicion of chest pain induced by hyperventilation in 24 cases, suggested a cause for equivocal ST depression other than coronary stenosis in five patients, and led to the diagnosis of previously unsuspected respiratory disease in 14 patients.Measurement of end tidal Pco₂ gives additional valuable diagnostic information during the conventional treadmill exercise test in patients with both typical and atypical chest pain.     

Maximal lactate steady-state prediction through quadratic modeling of selected stages of the lactate minimum test

In this study, we compared the maximal lactate steady state (MLSS) with lactate minimal (LM) intensities determined visually and through a quadratic polynomial function of selected stages of LM test. Eleven male recreational cyclists (27.7 +/- 4.5 years, 175.7 +/- 5.6 cm, 69.5 +/- 10.8 kg, and 12.0 +/- 5.5% body fat) performed one LM test under previous induction of hyperlactaemia with an initial intensity of 75 W with 30-W increments every 3 minutes with blood lactate concentration (HLa) and rating of perceived exertion (RPE) measurements. The LM intensity was determined visually (VLM) and by modeling the lactate response through polynomial function by using: 1) all stages (LMP); 2) the first stage, the stage corresponding to RPE-13 and the last stage/exhaustion (LMP3max); 3) the three lowest lactate concentration stages (LMP3adj); and 4) the initial, RPE-13, and RPE-16 stages (LMP3sub). The MLSS was determined as the highest intensity at a variation not greater than 0.05 mmol.l.min of HLa during the last 20 minutes of a 30-minute exercise session. The MLSS (204.0 +/- 16.0 W), VLM (198.6 +/- 15.2 W), LMP3adj (190.4 +/- 12.9 W), and LMP3sub (192.1 +/- 27.2 W) were not different, well correlated, and in agreement to each other. In conclusion, the polynomial modeling of HLa response to three submaximal stages produced exercise intensities that did not differ from MLSS.     

Differential arterial blood flow response of splanchnic and renal organs during low-intensity cycling exercise in women

To investigate the regional hemodynamic responses of abdominal arteries at the onset of exercise and to focus on their transient responses, eight female subjects (21-30 yr) performed ergometer cycling exercise at 40 W for 4 min in a semi-supine position. Mean blood velocities (MBVs) in the right renal (RA), superior mesenteric (SMA), and splenic (SA) arteries were measured by pulsed echo-Doppler ultrasonography, with beat-by-beat measurements of heart rate (HR) and mean arterial pressure (MAP). The vascular resistance index (RI) of each artery was calculated from MBV/MAP. MAP (76 +/- 9 to 83 +/- 8 mmHg at 4 min) and HR (60 +/- 7 to 101 +/- 9 beats/min at 4 min) increased during exercise (P < 0.05). The MBV of RA and SA rapidly decreased after the onset of exercise (30 s; -19 +/- 5% and -19 +/- 12%, respectively), reaching -27 +/- 7% and -27 +/- 15% at the end of exercise (P < 0.05). RI did not change during the initial 30 s of exercise, reflecting a reduction in MAP, and increased toward the end of the exercise (+55 +/- 21% and +59 +/- 39%, respectively). In contrast, both the MBV and RI in the SMA remained constant throughout the exercise. The results indicate that, whereas the responses of renal and splenic vessels changed similarly throughout the protocol, the vascular response of SMA that mainly supplies blood to the intestinal tract was unchanged during exercise. We, therefore, conclude that low-intensity cycling exercise resulted in differential blood flow responses in arteries supplying the abdominal organs.     

H-FABP、cTnI及copeptin在老年急性非ST段抬高型心肌梗死患者早期诊断中的应用价值

目的:研究心肌型脂肪酸结合蛋白(H-FABP)、肌钙蛋白I(cTnI)及和肽素(copeptin)在老年急性非ST段抬高型心肌梗死患者早期诊断中的应用价值。方法:选取2016年2月-2018年2月我院收治的老年急性非ST段抬高型心肌梗死患者60例为研究对象,记为观察组。另取同期于我院接受治疗的心绞痛患者50例记为对照组。分别比较患者H-FABP与cTnI阳性、阴性分布情况以及copeptin表达水平。绘制受试者工作特征曲线(ROC),分析H-FABP、cTnI、copeptin以及三项联合检测老年急性非ST段抬高型心肌梗死的早期诊断价值。结果:观察组患者H-FABP与cTnI阳性人数占比均高于对照组(P0.05)。观察组患者copeptin表达水平高于对照组(P0.05)。H-FABP、cTnI及copeptin等3个指标均具有一定的早期诊断价值,H-FABP+cTnI+copeptin联合检测的敏感度和特异度更高,分别为86.46%和87.15%。结论:老年急性非ST段抬高型心肌梗死患者H-FABP、cTnI、copeptin表达较高,联合检查上述三项指标水平可提高临床诊断价值。     

Effects of intense exercise training on plasma catecholamines in coronary patients

This paper reports the effect of 12 mo of intense endurance exercise training on the plasma catecholamine response to exercise in 11 male patients [aged 50 +/- 8 yr (mean +/- SD)] with coronary artery disease. A substantial adaptation to training was attained as evidenced by a 42% increase in maximum O2 uptake capacity. At rest, heart rate was lower after training, but resting blood pressure and plasma catecholamines were unchanged. At the same absolute work rate, plasma norepinephrine and epinephrine levels, rate pressure product, and ischemic S-T segment depression were all significantly lower after training. A higher plasma norepinephrine level was attained at maximal exercise after training (2,049 +/- 654 before vs. 3,408 +/- 1,454 pg/ml after, P less than 0.025); this was associated with a higher systolic blood pressure (175 +/- 25 before vs. 188 +/- 22 mmHg after, P less than 0.025) and a higher rate-pressure product (25.3 X 10(3) +/- 4.5 X 10(3) before vs. 27.6 X 10(3) +/- 5.2 X 10(3) after, P less than 0.025). Despite the higher plasma norepinephrine level and rate pressure product, S-T segment depression at maximal exercise was unchanged. These findings suggest that some patients with coronary arterial disease can attain a higher myocardial O2 requirement, without electrocardiographic evidence of increased ischemia, after prolonged strenuous exercise training.     

The importance of indicators of the initial phase of atherosclerosis in patients with microvascular angina

Endothelial dysfunction (ED) is generally considered to be the initial step in the progression to atherosclerosis but there is still much uncertainty about the role of the microvascular form of angina in patients with a normal coronary angiogram with regard to ED. The authors investigated the extent of endothelial perturbation and thereby whether the microvascular form of angina precedens macroscopic atherosclerosis by means of non-invasive ultrasound measurement of the intima-media thickening (IMT) in common carotid artery and flow mediated dilatation (FMD) in the brachial artery. 28 patients with stable angina with positive exercise test and ST segment depression (22 females, 6 males, average age 54 years) were compared with a control group consisting of 28 patients with no clinical signs of coronary artery disease (18 females, 10 males, average age 53 years). No significant difference in FMD% (7.3 vs. 10.8, p = 0.07) was found between the groups, though specific measurements (average dilatation of the brachial artery induced by ischemic insult, peak blood flow and peak hyperemic flow) differed considerably. Also IMT did not vary significantly between the groups (0.74 vs. 0.65, p = 0.08). In patients with IMT > 0.8 mm (6 patients in each group) a significant decrease of FMD was found as compared with patients with normal IMT (p < 0.05). It was concluded that in patients with increased IMT an inverse relationship between FMD and IMT exists both in patients with microvascular angina and in the healthy control subjects whereas in the group of patients with normal IMT no ED was demonstrated. This supports the hypothesis that the microvascular form of angina is the early stage of coronary artery atherosclerosis and this escapes angiographic recognition.     

Plasma norepinephrine and heart rate dynamics during recovery from submaximal exercise in man

The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expression of the sympathetic nervous activity (SNA), was studied in six sedentary young men during recovery from three periods of cycle ergometer exercise at 21% +/- 2.8%, 43% +/- 2.1% and 65% +/- 2.3% of VO2max respectively (mean +/- SE). The HR decreased mono-exponentially with tau values of 13.6 +/- 1.6 s, 32.7 +/- 5.6 s and 55.8 +/- 8.1 s respectively in the three periods of exercise. At the low exercise level no change in [NE] was found. At medium and high exercise intensity: (a) [NE] increased significantly at the 5th min of exercise (delta [NE] = 207.7 +/- 22.5 pg.ml-1 and 521.3 +/- 58.3 pg.ml-1 respectively); (b) after a time lag of 1 min [NE] decreased exponentially (tau = 87 s and 101 s respectively); (c) in the 1st min HR decreased about 35 beats.min-1; (d) from the 2nd to 5th min of recovery HR and [NE] were linearly related (100 pg.ml-1 delta [NE] congruent to 5 beats.min-1). In the 1st min of recovery, independent of the exercise intensity, the adjustment of HR appears to have been due mainly to the prompt restoration of vagal tone. The further decrease in HR toward the resting value could then be attributed to the return of SNA to the pre-exercise level.     

24 Hour ST Segment Analysis in Transient Left Ventricular Apical Ballooning

Objective

The etiologic basis of transient left ventricular apical ballooning, a novel cardiac syndrome, is not clear. Among the proposed pathomechanisms is coronary vasospasm. Long-term ST segment analysis may detect vasospastic episodes but has not been reported.

Methods

30 consecutive patients with transient left ventricular apical ballooning, left ventricular dysfunction and normal or near-normal coronary arteries were investigated. A 24-hour Holter ECG was obtained after emergency admission. ST segment analysis was performed automatically in 2 leads and confirmed by visual inspection. Criteria for an ischemic event were: 1. ST elevation or 2. horizontal or down-sloping ST segments ≥1 min duration and ≥100 µV J+80 point deviation corrected for baseline ST-deviation.

Results

Patients presented with ST segment elevation (n = 19) and/or T wave inversion (n = 20) on admission ECG. Ejection fraction was 50±12%. No transient ST elevations were observed during Holter ECG analysis. In 3 patients, 8 transient episodes of ST depression were recorded. Durations of episodes varied between 75s and 790s (mean 229s). Maximal ST deviation averaged −191±71 µV. Ischemic burden was −1 to −22 mVs (mean −8 mVs). 27 patients showed no ischemic events.

Conclusions

ST segment analysis of 24 h Holter recordings revealed minor ischemic events in only 10% of patients with transient left ventricular apical ballooning. Overall, ST segment changes were not indicative of recurrent coronary spasm playing a major role in the genesis of transient left ventricular apical ballooning.     

Left ventricular hemodynamics during exercise recovery

The directional response of human left ventricular stroke volume during exercise recovery is unclear. Stroke volume has been reported to increase and decrease over exercise values during early recovery. The confounding variable may be posture. With the use of pulsed Doppler ultrasound, we tested the hypothesis that there is a significant difference between seated and supine stroke index (SI) during passive recovery from seated ergometer exercise. Thirteen subjects aged 26 +/- 2 yr performed two seated cycle ergometer exercise tests to 70% of predicted maximum heart rate (HR). Recovery was supine on one test and seated on the other. Cardiac index (CI), HR, and SI were calculated during rest, exercise, and 10 min of recovery. At rest, SI and CI were significantly (P less than 0.01) less and HR significantly (P less than 0.01) greater when the subjects were seated than when they were supine. At the last exercise work load, no significant differences were found in any measured variable between tests. During recovery, supine SI was maximal 180 s postexercise (99 +/- 14 ml/m2) and exceeded (P less than 0.01) resting supine (81 +/- 14 ml/m2) and peak exercise (77 +/- 14 ml/m2) SI by 22 and 29%, respectively. Seated SI was constant at peak exercise levels for 2 min. Seated and supine recovery CI never exceeded exercise values. Systolic and diastolic blood pressure recovery curves were similar in the two postures. We conclude that posture significantly affects SI during recovery from submaximal seated exercise. These results have implications for choice of recovery posture after stress testing in cardiac patients where it is desirable to minimize ventricular loading.     

Changes in regional cerebral blood flow distribution during postexercise hypotension in humans.

This investigation compared patterns of regional cerebral blood flow (rCBF) during exercise recovery both with and without postexercise hypotension (PEH). Eight subjects were studied on 3 days with randomly assigned conditions: 1) after 30 min of rest; 2) after 30 min of moderate exercise (M-Ex) at 60-70% heart rate (HR) reserve during PEH; and 3) after 30 min of light exercise (L-Ex) at 20% HR reserve with no PEH. Data were collected for HR, mean blood pressure (MBP), and ratings of perceived exertion and relaxation, and rCBF was assessed by use of single-photon-emission computed tomography. With the use of ANOVA across conditions, there were differences (P < 0.05; mean +/- SD) from rest during exercise recovery from M-Ex (HR = +12 +/- 3 beats/min; MBP = -9 +/- 2 mmHg), but not from L-Ex (HR = +2 +/- 2 beats/min; MBP = -2 +/- 2 mmHg). After M-Ex, there were decreases (P < 0.05) for the anterior cingulate (-6.7 +/- 2%), right and left inferior thalamus (-10 +/- 3%), right inferior insula (-13 +/- 3%), and left inferior anterior insula (-8 +/- 3%), not observed after L-Ex. There were rCBF decreases for leg sensorimotor regions after both M-Ex (-15 +/- 4%) and L-Ex (-12 +/- 3%) and for the left superior anterior insula (-7 +/- 3% and -6 +/- 3%), respectively. Data show that there are rCBF reductions within specific regions of the insular cortex and anterior cingulate cortex coupled with a postexercise hypotensive response after M-Ex. Findings suggest that these cerebral cortical regions, previously implicated in cardiovascular regulation during exercise, may also be involved in PEH.