The Significance of Hyperventilative and Orthostatic T-Wave Changes on the Electrocardiogram

Kemp, George L.

doi:10.1001/archinte.1968.03640060032006

Cited by 36 publications

(7 citation statements)

References 11 publications

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“…Furthermore, our reduction was detected after 10 min of hypocapnia, whereas measurements during voluntary hyperventilation are sometimes made after only 60 s or less and without Pa CO 2 measurement (22,26,31,58). This reduction occurred in 13 of 15 normal subjects and is therefore much more reproducible than any effect during voluntary hyperventilation (16,20,22,58).…”

Section: Ajp-regul Integr Comp Physiolmentioning

confidence: 69%

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Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

Rutherford¹,

Clutton-Brock²,

Parkes³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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During voluntary hyperventilation in unanesthetized humans, hypocapnia causes coronary vasoconstriction and decreased oxygen (O 2) supply and availability to the heart. This can induce local epicardial coronary artery spasm in susceptible patients. Its diagnostic potential for detection of early heart disease is unclear. This is because such hypocapnia produces an inconsistent and irreproducible effect on electrocardiogram (ECG) in healthy subjects. To resolve this inconsistency, we have applied two new experimental techniques in normal, healthy subjects to measure the effects of hypocapnia on their ECG: mechanical hyperventilation and averaging of multiple ECG cycles. In 15 normal subjects, we show that hypocapnia (20 Ϯ 1 mmHg) significantly reduced mean T wave amplitude by 0.1 Ϯ 0.0 mV. Hypocapnia also increased mean heart rate by 4 beats/min without significantly altering blood pressure, ionized calcium or potassium levels, or the R wave or other features of the ECG. We therefore provide the first unequivocal demonstration that hypocapnia does consistently reduce T wave amplitude in normal, healthy subjects. coronary circulation; carbon dioxide; angina DURING VOLUNTARY HYPERVENTILATION in unanesthetized humans, hypocapnia causes coronary vasoconstriction and decreased oxygen (O 2 ) supply and availability to the heart. Thus cardiac catheterization studies show that voluntary hyperventilation [to partial pressure levels of carbon dioxide in arterial blood (Pa CO 2 ) of 20 mmHg] increases coronary vascular resistance by 17% (47), decreases coronary blood flow by 30% (47), and increases the affinity of hemoglobin for O 2 by 25% (35). During voluntary hyperventilation, hypocapnia can induce local epicardial coronary artery spasm in single or multiple vessels with associated ST displacement, both in susceptible patients with voluntary hyperventilation syndrome (but without symptoms of heart disease) (15, 24) and in the rare group of patients with Prinzmetal's variant angina (29,59).It is unclear whether this effect has any diagnostic potential for early coronary heart disease. This is because numerous studies in healthy subjects report that hypocapnia produces only inconsistent decreases in the amplitude of the ECG T wave that are not reproducible in every subject (5,6,8,16,20,22,30,49,54,58).Such inconsistency is not surprising because of the methodological difficulties inherent with voluntary hyperventilation in the variability of inflation volumes achieved and of the duration, level, and stability of hypocapnia. Variability in movement of the body surface (and its attached electrodes) relative to the heart with each inflation introduces a crucial artifact that alone might explain this inconsistency. These difficulties are compounded by the lack of a standardized procedure for ECG analysis during hyperventilation. It is unclear precisely how many ECG complexes were measured, how they were selected, and what was their precise relationship to the inflation cycle (6,16,58,60).We have therefore applied two novel ap...

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Section: Ajp-regul Integr Comp Physiolmentioning

confidence: 69%

“…This is because numerous studies in healthy subjects report that hypocapnia produces only inconsistent decreases in the amplitude of the ECG T wave that are not reproducible in every subject (5,6,8,16,20,22,30,49,54,58).…”

mentioning

confidence: 99%

Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

Rutherford¹,

Clutton-Brock²,

Parkes³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Other physiologic explanations for minor NSSTTA include hyperventilation, hyperkinetic heart syndrome, lesions of the central nervous system, abnormalities in left ventricular wall motion in the absence of coronary artery disease, persistent juvenile pattern, electrolyte disturbance, use of drugs (ie, digitalis, antiarrhythmic, and psychotrophic drugs), or athletic ability. [33][34][35][36] None of these diverse mechanisms, however, seems to explain the significant independent association between isolated minor NSSTTA and incident CVD that has been observed in large population-based studies. It has been suggested, therefore, that minor NSSTTA may represent subclinical coronary artery disease, 1 early left ventricular hypertrophy (LVH), or increased left ventricular (LV) mass, 37 or autonomic imbalance.…”

Section: Physiological Significance Of Isolated Minor Nssttamentioning

confidence: 99%

Clinical Significance of Minor Nonspecific ST-Segment and T-Wave Abnormalities in Asymptomatic Subjects: A Systematic Review

Kumar

Lloyd‐Jones

2007

Cardiology in Review

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The purpose of the study is to examine the prevalence and significance of minor nonspecific ST-segment and T-wave abnormalities (NSSTTA) in the prediction of future cardiovascular disease (CVD) events. Minor NSSTTA are commonly encountered in clinical practice. To date, there have been no systematic reviews focusing on the prevalence and prognostic importance of these findings. Literature searches of MEDLINE (1966-2005) were supplemented with searches of bibliographies from key articles. We focused on isolated minor NSSTTA in healthy middle-aged or elderly populations, including men, women, blacks, and whites, and the association of isolated minor NSSTTA with incident cardiovascular and coronary events. Isolated minor NSSTTA are common in middle-aged white men (ranging from 3.6% to 10.3%), and seem to be even more prevalent in women, blacks, and the elderly. In the 3 studies that examined isolated minor NSSTTA, the multivariable-adjusted hazard ratios for coronary mortality ranged from 1.24 to 1.66. Although gender, race, and age-specific differences in the prognostic significance of minor NSSTTA are not clear because of limited data, minor NSSTTA in asymptomatic patients are an important risk factor for coronary and cardiovascular mortality, independent of traditional risk factors. Minor NSSTTA are prevalent in asymptomatic individuals, and they confer increased risk for CVD and coronary heart disease (CHD), independent of traditional risk factors. Future studies with standardized methodology are needed to elucidate the physiological significance of minor NSSTTA and to further describe gender, race, and age-related differences in the prevalence and prognostic significance of minor NSSTTA.

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“…ST-T abnormalities may well reflect different proportions of various entities in men and women. ST-T abnormalities have been described in a number of situations besides coronary artery disease, including change in posture, 23 abnormal ST-T waves have myocardial ischemia without significant coronary atherosclerosis. Possible mechanisms include abnormal oxyhemoglobin dissociation`and small-vessel disease, perhaps related to estrogen-induced changes in the clotting mechanism28 or to changes in myocardial lactate metabolism.30 It may be that prognosis for individuals with such myocardial ischemia is different than that for those with ST-T related ischemia due to coronary atherosclerosis.…”

Section: Circulationmentioning

confidence: 99%

Sex differential in the relationship of electrocardiographic ST-T abnormalities to risk of coronary death: 11.5 year follow-up findings of the Chicago Heart Association Detection Project in Industry.

Liao¹,

Liu²,

Dyer³

et al. 1987

Circulation

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The independent contributions of ST segment depression and/or T wave abnormality (ST-T abnormalities) on the baseline resting electrocardiogram to risk of 11.5 year coronary heart disease (CHD) mortality were explored among 9203 white men and 7818 white women who were 40 to 64 years old and without definite CHD at entry in the Chicago Heart Association Detection Project in Industry. At baseline, prevalence rates of ST-T abnormalities were age related for both sexes, and at every age the rate was higher in women than men (age-adjusted prevalence rates 12.3% and 8.1%, respectively). Univariate analysis showed that ST-T abnormalities were associated with significantly increased risk of death from CHD for both men and women. However, men with ST-T abnormalities had much greater age-adjusted and multiple risk factor-adjusted absolute excess risk and relative risk than women with such electrocardiographic abnormalities. When baseline age, diastolic pressure, serum cholesterol, cigarettes/day, history of diabetes, and baseline use of antihypertensive medication were included in the multivariate analysis, ST-T abnormalities remained significantly related to death from CHD in men but not women. The interaction term between sex and ST-T abnormalities was at a borderline level of statistical significance by Cox regression analysis. In conclusion, ST-T abnormalities indicate an increased risk of subsequent death from CHD independent of major coronary risk factors for middle-aged U.S. men, but this is not clearly so for women. Circulation 75, No. 2, 347-352, 1987. ST SEGMENT DEPRESSION and/or T wave abnormalities on the resting electrocardiogram are among the most common findings encountered in clinical examination of patients, in screening asymptomatic adults, and in epidemiologic surveys. The association of ST-T abnormalities with increased coronary heart disease (CHD) mortality was reported in insurance experience over 30 years ago.`2 Subsequently, the

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The Significance of Hyperventilative and Orthostatic T-Wave Changes on the Electrocardiogram

Cited by 36 publications

References 11 publications

Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

Clinical Significance of Minor Nonspecific ST-Segment and T-Wave Abnormalities in Asymptomatic Subjects: A Systematic Review

Sex differential in the relationship of electrocardiographic ST-T abnormalities to risk of coronary death: 11.5 year follow-up findings of the Chicago Heart Association Detection Project in Industry.

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