The hyperventilation challenge test. Another means of identifying coronary vasospasm in patients with angina-like chest pain

Hyperventilation testing in the diagnosis of vasospastic angina: A clinical review and meta-analysis

BACKGROUND

Given the limited access to invasive vasospastic reactivity testing in Western Countries, there is a need to further develop alternative non-invasive diagnostic methods for vasospastic angina (VSA). Hyperventilation testing (HVT) is defined as a class IIa recommendation to diagnose VSA by the Japanese Society of Cardiology.

METHODS

In this systematic review and meta-analysis reported according to the PRISMA statement, we review the mechanisms, methods, modalities and diagnostic accuracy of non-invasive HVT for the diagnostic of VSA.

RESULTS

A total of 106 articles published between 1980 and 2022 about VSA and HVT were included in the systematic review, among which 16 were included in the meta-analysis for diagnostic accuracy. Twelve electrocardiogram-HVT studies including 804 patients showed a pooled sensitivity of 54% (95% confidence intervals [CI]; 30%-76%) and a pooled specificity of 99% (95% CI; 88%-100%). Four transthoracic echocardiography-HVT studies including 197 patients revealed a pooled sensitivity of 90% (95% CI; 82%-94%) and a pooled specificity of 98% (95% CI; 86%-100%). Six myocardial perfusion imaging-HVT studies including 112 patients yielded a pooled sensitivity of 95% (95% CI; 63%-100%) and a pooled specificity of 78% (95% CI; 19%-98%). Non-invasive HVT resulted in a low rate of adverse events, ventricular arrhythmias being the most frequently reported, and were resolved with the administration of nitroglycerin.

CONCLUSIONS

Non-invasive HVT offers a safe alternative with high diagnostic accuracy to diagnose VSA in patients with otherwise undiagnosed causes of chest pain.

Use of intraoperative mild hyperventilation to decrease the incidence of postoperative shoulder pain after laparoscopic gastric sleeve surgery: A prospective randomised controlled study

BACKGROUND AND AIMS

Post-laparoscopic shoulder pain (PLSP) is a common problem. It is a referred type of pain resulting from irritation of phrenic nerve endings. Multiple manoeuvres were used to decrease its incidence with varying success rates. In this study, we tested the use of mild intraoperative hyperventilation to reduce PLSP in patients undergoing laparoscopic sleeve gastrectomy surgery (LSG).

METHODS

Consenting American Society of Anesthesiologists-I and II patients undergoing LSG under general anaesthesia were randomly assigned to two groups. Group A (53 patients) received intraoperative mild hyperventilation with target end-tidal carbon dioxide (ETCO2) of 30-32 mmHg. Group B (51 patients) received conventional ventilation (ETCO2 of 35-40 mmHg). Incidence and severity of PLSP, cumulative analgesic requirements and incidence of nausea and vomiting were recorded at 12 and 24 hours postoperatively and then followed up after discharge over the phone at 48 hours, 1 week, 1 month and 3 months. Statistical significance of differences between the two groups was defined at P < 0.05.

RESULTS

Incidence of PLSP was comparable between the two groups in the first 24 hours. The intervention group had a significantly lower incidence of PLSP throughout the remaining assessment points (56.6% vs. 80.4%, 30.2% vs. 78.4%, 15.1% vs. 70.6%, 3.8% vs. 35.3% at 36 hours, 48 hours, 1 week and 1 month, respectively, P < 0.05). The average PLSP pain score was significantly lower in the mild hyperventilation group at all assessment time points. Nausea and vomiting were non-significantly lower in the mild hyperventilation group.

CONCLUSION

Mild intraoperative hyperventilation could be beneficial in reducing the incidence and severity of PLSP after LSG surgery.

Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association

Cardiovascular disease is the leading cause of mortality in American women. Since 1984, the annual cardiovascular disease mortality rate has remained greater for women than men; however, over the last decade, there have been marked reductions in cardiovascular disease mortality in women. The dramatic decline in mortality rates for women is attributed partly to an increase in awareness, a greater focus on women and cardiovascular disease risk, and the increased application of evidence-based treatments for established coronary heart disease. This is the first scientific statement from the American Heart Association on acute myocardial infarction in women. Sex-specific differences exist in the presentation, pathophysiological mechanisms, and outcomes in patients with acute myocardial infarction. This statement provides a comprehensive review of the current evidence of the clinical presentation, pathophysiology, treatment, and outcomes of women with acute myocardial infarction.

Carbon Dioxide and the Heart: Physiology and Clinical Implications

Carbon dioxide (CO2) is an end product of aerobic cellular respiration. In healthy persons, PaCO2 is maintained by physiologic mechanisms within a narrow range (35-45 mm Hg). Both hypercapnia and hypocapnia are encountered in myriad clinical situations. In recent years, the number of hypercapnic patients has increased by the use of smaller tidal volumes to limit lung stretch and injury during mechanical ventilation, so-called permissive hypercapnia. A knowledge and appreciation of the effects of CO2 in the heart are necessary for optimal clinical management in the perioperative and critical care settings. This article reviews, from a historical perspective: (1) the effects of CO2 on coronary blood flow and the mechanisms underlying these effects; (2) the role of endogenously produced CO2 in metabolic control of coronary blood flow and the matching of myocardial oxygen supply to demand; and (3) the direct and reflexogenic actions of CO2 on myocardial contractile function. Clinically relevant issues are addressed, including the role of increased myocardial tissue PCO2 (PmCO2) in the decline in myocardial contractility during coronary hypoperfusion and the increased vulnerability to CO2-induced cardiac depression in patients receiving a β-adrenergic receptor antagonist or with otherwise compromised inotropic reserve. The potential use of real-time measurements of PmO2 to monitor the adequacy of myocardial perfusion in the perioperative period is discussed.

Anginalike pain and normal coronary arteries

Atherosclerotic CAD is the most common cause of cardiac chest pain in Western countries. Other cardiac syndromes may also cause anginalike pain and may be difficult to differentiate from atherosclerotic CAD. It is essential to make this distinction, because management and prognosis of these conditions are entirely different. A detailed history and, in some cases, special diagnostic methods can help make the diagnosis. When evaluating patients with anginalike chest pain and normal coronary arteries, physicians need to consider this group of diseases and tailor workup and diagnosis on an individual basis.

Disruption of coronary vasomotor function: the coronary spasm syndrome

Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically as a coronary syndrome and plays an important role in the genesis of myocardial ischemia. Over the past half century, coronary angiography allowed the in vivo demonstration of spasm in patients who fit the initial clinical description of the condition as reported by Prinzmetal et al. Several clinical, basic, and more recently, genetic studies have provided insight into the pathogenesis, manifestations, and therapy of this condition. It is not uncommonly encountered in patients with coronary syndromes and absence of clearly pathologic lesions on angiography. Provocation tests utilizing pharmacologic and nonpharmacologic stimuli combined with imaging (echocardiography or coronary angiography) can help make the correct diagnosis. The use of calcium channel blockers and long-acting nitrates is currently considered standard of care and the overall prognosis appears to be good. The recent discovery of genetic abnormalities predisposing to abnormal spasm of the coronaries has stimulated interest in the development of targeted therapies for the management of this condition.

Depression with panic episodes and coronary vasospasm

Variant (Prinzmetal's) angina is an uncommon cause of precordial pain caused by coronary vasospasm and characterized by transient ST elevation and negative markers of myocardial necrosis. This is the case of a female patient with a prior history of depression and panic attacks who presented with recurrent symptoms including chest pain. A cardiac event monitor positively documented coronary vasospasm associated with anxiety-provoking chest pain, whereas the coronary arteries were angiographically normal. We noted that the frequency of angina attacks apparently increased during the period that coincided with the introduction of Bupropion SR for treatment of the patient's depression. Considering the possibility of bupropion-associated negative impact on coronary vasospasm, the antidepressant therapy was adjusted to exclude this drug. Although Prinzmetal's angina is relatively uncommon, we suspect that a routine use of cardiac event monitors in subjects with panic disorder might reveal a greater incidence of coronary vasospasm in this patient population.

Detection of coronary vasospasm by posthyperventilation technetium-99m sestamibi single-photon emission computed tomography imaging in patients with coronary artery disease

Forced hyperventilation is simple, safe to perform, and can be used as a provocative test for coronary vasospasm. This study assesses whether a vasospastic component of angina might be detected in patients with angiographically "nonobstructive" coronary artery disease by posthyperventilation technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) cardiac imaging. Eleven patients with angiographically nonobstructive coronary artery disease underwent Tc-99m sestamibi SPECT imaging at rest and after forced hyperventilation. Vessel diameters were measured by quantitative angiography before and after forced hyperventilation, and posthyperventilation SPECT images were compared with dipyridamole Tc-99m sestamibi stress images. Forced hyperventilation resulted in a 15% reduction in coronary artery diameter in stenotic segments (p <0.01), and a 17% reduction in adjacent nonstenotic segments (p <0.001). Myocardial uptake of Tc-99m sestamibi in segments perfused by vessels with angiographically nonobstructive stenoses was reduced by 24% following forced hyperventilation (p <0.001) compared with only 4% following dipyridamole (p <0.02). These findings suggest that posthyperventilation Tc-99m sestamibi SPECT imaging in patients with angina pectoris and nonobstructive coronary artery disease may be useful in identifying a vasospastic component of angina.

Plasma protein acute-phase response in unstable angina is not induced by ischemic injury

BACKGROUND

Elevated levels of C-reactive protein (CRP) are associated with an unfavorable clinical outcome in patients with unstable angina. To determine whether ischemia-reperfusion injury causes this acute-phase response, we studied the temporal relation between plasma levels of CRP and ischemic episodes in 48 patients with unstable angina and 20 control patients with active variant angina, in which severe myocardial ischemia is caused by occlusive coronary artery spasm.

METHODS AND RESULTS

Blood samples were taken on admission and subsequently at 24, 48, 72, and 96 hours. All patients underwent Holter monitoring for the first 24 hours and remained in the coronary care unit under ECG monitoring until completion of the study. On admission, CRP was significantly higher in unstable angina than in variant angina patients (P < .001). In unstable angina, 70 ischemic episodes (1.5 +/- 2 per patient) and in variant angina 192 ischemic episodes (9.6 +/- 10.7 per patient) were observed during Holter monitoring (P < .001), for a total ischemic burden of 14.8 +/- 30.2 and 44.4 +/- 57.2 minutes per patient, respectively (P < .001). The plasma concentration of CRP did not increase in either group during the 96 hours of study, even in patients who had episodes of ischemia lasting > 10 minutes.

CONCLUSIONS

The normal levels of CRP in variant angina, despite a significantly larger number of ischemic episodes and greater total ischemic burden, and the failure of CRP values to increase in unstable angina indicate that transient myocardial ischemia, within the range of duration observed, does not itself stimulate an appreciable acute-phase response.