Altitude and the heart: is going high safe for your cardiac patient?

Our aging population combined with the ease of travel and the interest in high altitude recreation pursuits exposes more patients to the acute physiologic effects of high altitude and lower oxygen availability. Acute exposure to high altitude is associated with significant alterations to the cardiovascular system. These may be important in patients with underlying cardiovascular disease who are not able to compensate to such physiologic changes. Exacerbating factors pertinent to patients with cardiovascular disease include acute hypoxia, increased myocardial work, increased epinephrine release, and increased pulmonary artery pressures. This review summarizes the physiology and clinical evidence regarding acute altitude exposure on the cardiopulmonary system with practical recommendations to address the question: "Is it safe for me to ski in the Rockies or climb Mt. Kilimanjaro?"

Electrocardiographic exercise stress testing: an update beyond the ST segment.

Routine exercise testing is frequently ordered to evaluate a patient's cardiovascular performance. The test is more direct and less expensive than imaging technology, and derives valuable information. New variables such as dyspnea and heart rate recovery, as well as integrated scores, provide incremental value to conventional analysis of exercise-induced angina or electrocardiographic changes. Considerations relating to test accuracy in women need to be weighed. This paper seeks to make physicians aware of the current status of the test, and improve their understanding of and ability to integrate new variables and scores to more effectively manage their patients.

Stress-induced abnormalities in myocardial perfusion imaging that are not related to perfusion but are of diagnostic and prognostic importance.

INTRODUCTION: Certain stress-induced ancillary findings on myocardial perfusion scintigraphy increase the likelihood that the patient has coronary artery disease (CAD); furthermore, among CAD patients, they indicate more severe and extensive disease, placing these patients at higher risk for future cardiac events. Indeed, in studies with no obvious perfusion defect yet with serious CAD--for example, balanced ischemia--it can be these high-risk findings that necessitate invasive intervention. DISCUSSION: Besides reversible perfusion defects, such findings include increased pulmonary radiotracer uptake, transient cavity dilatation, increased end-diastolic or end-systolic volume, decreased post-stress ejection fraction, and increased right ventricular tracer uptake on stress images. The pathophysiology underlying these findings is clearly different as they do not always occur together, and each independently predicts more severe and extensive CAD. In the current review, these findings are defined and their significance in diagnosing patients with suspected or known CAD is discussed.

Left bundle-branch block artifact on single photon emission computed tomography with technetium Tc 99m (Tc-99m) agents: mechanisms and a method to decrease false-positive interpretations.

Myocardial perfusion scintigraphy is a well validated noninvasive method of evaluating for significant coronary artery disease, especially in cases where electrocardiographic changes are nondiagnostic, including left bundle-branch block. However, such testing with a technetium Tc 99m agent is often confounded by left ventricular septal-based false-positive perfusion defects. These defects can be either reversible or irreversible in the septal or anteroseptal wall, problematically then, in the territory supplied by the left anterior descending coronary artery. Mechanisms explaining false-positive defects include decreased perfusion via impaired microvessel flow and normal perfusion with apparent decrease in counts in a relatively thin septum (partial-volume effect). Key findings in myocardial perfusion images in the presence of left bundle-branch block that define true positives (ischemia) are reversible perfusion defects (especially at end diastole), a concomitant apical defect, and systolic dysfunction matching the perfusion defect.

Elevation of cardiac troponin I indicates more than myocardial ischemia.

Elevated cardiac troponin I (cTnI) levels in patients hospitalized with chest pain often lead to a diagnosis of acute myocardial infarction (MI) or unstable angina. However, as we describe in this review, this finding may occur in other conditions, leading to an incorrect diagnosis and other, sometimes invasive, tests. We review briefly cTnI, its release and detection. We describe the various conditions that may cause an elevated cTnI level and give possible explanations for these findings, and we offer some guidelines for diagnosis in patients with an elevated cTnI.

Peripheral arterial disease--Part II: Management.

While knowledge about peripheral arterial disease (PAD) appears well disseminated, the condition still goes largely undiagnosed and untreated. In PART 1 of this paper, we summarized the diagnosis, epidemiology and risk factors for PAD. Non-invasive treatment involves management of risk factors and targeted drug therapy. Invasive strategies include angioplasty, angiogenesis and surgery. Dealing with both the structural factors (physical plaque morphology) and functional ones (endothelial function) are important in effectively managing PAD. This paper (PART 2) deals with the management (medical and surgical) of PAD.

Epidemiology of peripheral arterial disease in women.

BACKGROUND: Peripheral arterial disease is a common disease, which increases with age and presence of vascular risk factors. The extended longevity in industrialized nations coupled with the expanding elderly female population is predicted to lead to an increase in the prevalence of this condition. Little attention has been focussed on gender differences in peripheral arterial disease, or its epidemiology in women. METHODS: MEDLINE search of English-language reports published between 1966 and 2002 and search of references of relevant papers. RESULTS: Across various populations of women with different ages and risk factor levels, the prevalence of peripheral arterial disease ranged between 3% and 29%. Diagnosis in women using a sensitive and specific non-invasive test, the ankle-brachial index, detects about 3-5 times the cases than those diagnosed by history of intermittent claudication alone. Contrary to earlier beliefs, prevalence of peripheral arterial disease is similar in women and men, and women may have more asymptomatic disease. Importantly, women with peripheral arterial disease have 2-4 fold increases in cardiovascular morbidity and mortality. Risk factors for peripheral arterial disease appear to be similar in men and women, however relative risks vary somewhat. CONCLUSIONS: Performing non-invasive testing (e.g. ankle-brachial index) can better diagnose peripheral arterial disease in women than history alone. These women share risk factors with other vascular diseases (coronary and cerebrovascular disease) and should undergo risk factor modification to reduce their cardiovascular morbidity and mortality. More research is needed including aggressive risk factor management in women with asymptomatic peripheral arterial disease.

Chlamydia pneumoniae and coronary artery disease: legitimized linkages?

Chlamydia pneumoniae (Cp) infection in early life may accelerate atherosclerosis over ensuing decades, leading to cardiovascular complications. Cp promotes endothelial dysfunction and may modulate inflammation underlying atherosclerosis. It represents a biologically plausible candidate for the causation of atherosclerosis. Other infections simultaneously occurring with Cp may result in a synergistic effect to promote atherosclerosis. Studies on the treatment of Cp with antibiotics indicates decreased rates of infection, modulation of inflammation and in some settings, fewer cardiovascular complications.

Peripheral arterial disease--Part I: Diagnosis, epidemiology and risk factors.

While knowledge about peripheral arterial disease (PAD) appears well disseminated, the condition still goes largely undiagnosed and untreated. We reviewed the current literature and found that PAD is a common condition that is equally prevalent in men and women. Most cases are asymptomatic and more so in women. Having PAD increases morbidity and mortality, as well as concomitant cardiovascular disease. Given the lack of symptoms in most patients, we recommend diagnosing PAD using non-invasive instruments such as the Ankle-Brachial Index (ABI). This paper deals with the diagnosis, epidemiology and risk factors for PAD.