Heart failure: clinical implications of systolic and diastolic dysfunction

Morbidity and mortality from congestive heart failure (CHF) remain high for older patients with systolic or diastolic dysfunction. These two disease processes differ in clinical manifestations, physical findings, treatment options, and prognosis. No one physical findings is diagnostic, which underlines the importance of assessing LV function with Doppler echocardiography. Diastolic dysfunction has been shown to increase with age, although most data demonstrating effective medical therapy for CHF applies to patients with systolic dysfunction. The treatment of older patients with preserved systolic function and CHF is therefore difficult, due to incomplete understanding of diastolic dysfunction and limited data about specific drug therapies.

Heart protection: controlling risk factors for cardiovascular disease

Cardiovascular disease is the leading cause of illness and death in the United States. Clinical data continue to support primary prevention through the aggressive treatment of well-defined cardiovascular risk factors. Three risk factors that can be modified to lower the risk of cardiovascular disease and death are hypercholesterolemia, hypertension, and cigarette smoking. Even patients with asymptomatic cardiovascular disease have been shown to benefit from aggressive cholesterol-lowering therapy. New JNC-VI guidelines for managing hypertensive disease recommend that treatment decisions be based on level of blood pressure plus presence or absence of target organ damage or other risk factors. The risk of myocardial infarction in former smokers approaches that of nonsmokers after 3 years.

Mitral valve repair is superior to valve replacement for the early preservation of cardiac function: relation of ventricular geometry to function

The immediate effect or mitral valve repair (MVP) or replacement (MVR) on cardiac function was compared in patients with mitral regurgitation in relation to the changes in left ventricular (LV) function and geometry by using intraoperative transesophageal echocardiography in 29 patients with MVP and 21 patients with MVR, before and immediately after cardiopulmonary bypass. The LV volumes, ejection fraction, and long-axis and short-axis lengths and eccentricity index (ratio of long axis to short axis) at end-systole and end-diastole were measured. After both MVP and MVR, there were significant decreases in LV end-diastolic volume (p < 0.0001). However, the ejection fraction did not change after MVP, whereas it decreased after MVR (p < 0.0001). After MVP, there was an increase in eccentricity index at end-systole (p < 0.0001). After MVR, there was no decrease in end-systolic volume, and the eccentricity index was lower than that after MVP (p < 0.0001). The change in LV ejection fraction correlated with the changes in eccentricity index at end-systole (r = 0.55; p < 0.0001) and end-diastole (r = 0.42; p < 0.0003). Immediate intraoperative LV function is preserved after MVP but is depressed after MVR for mitral regurgitation. The changes in ejection fraction correlate with changes in ventricular geometry.

Ventricular tachycardia: progress in acute and chronic patient care

Patients with ventricular tachycardia (VT) typically have significant structural heart disease and therefore benefit from all advances made in the past 50 years in cardiovascular care. Once sinus rhythm is restored, subsequent treatment goals include detecting the primary causes of VT and treating acute recurrences, determining the extent of structural heart disease and assessing the need for treatment of heart failure and ischemia, and prescribing chronic antiarrhythmic therapy. Implantable-device therapy has revolutionized the treatment of patients with VT.

Sudden cardiac death from coronary artery spasm in a healthy subject

The true incidence of sudden cardiac death (SCD) from coronary artery spasm is unknown. The following case involves SCD in a previously asymptomatic young man with reasonable evidence to implicate coronary artery spasm as a potential cause for his clinical event. Ergonovine provocation may be warranted in patients who present with SCD and no discernable cause.

Doppler echocardiographic evaluation of the spectrum of left ventricular diastolic dysfunction in essential hypertension

Left ventricular topography and diastolic and systolic functions were studied in 41 patients with essential hypertension (group 1) and 33 age-matched normal adults (group 2) by Doppler echocardiography. In group 1 54% had LV concentric hypertrophy, 19% had combined concentric hypertrophy and eccentric remodeling, and 27% had concentric remodeling. LV systolic function was within the normal range. In concentric LV remodeling, the EDV was significantly decreased (compared with group 2) (84 +/- 15 vs 130 +/- 38 ml, p < 0.05), whereas the NPFR was normal (2.89 +/- 0.65 vs 3.22 +/- 0.83 sec-1, p = NS). In concentric hypertrophy, LV end-diastolic and end-systolic volumes were normal, but the NPFR was decreased (2.04 +/- 0.59 sec-1). Patients with concentric hypertrophy and eccentric remodeling had the largest end-diastolic (140 +/- 48 ml) and end-systolic (62 +/- 32 ml) volumes and the lowest NPFR (1.67 +/- 0.69 sec-1). The LVMI inversely correlated with the NPFR (r = -0.89, p < 0.0001). Thus LV concentric hypertrophy with or without concentric or eccentric remodeling is seen in patients with systemic hypertension. A decrease in peak filling occurs early in the evolution of hypertensive heart disease and is observed even when systolic performance is still normal.

The contraction of stunned myocardium: isovolumetric bulging and wasted ejection shortening in dog heart

OBJECTIVE

The aim of the study was to assess the contraction of myocardium stunned by repetitive brief coronary occlusions by examining the response to alterations in loading and inotropy of systolic contraction on isovolumetric and ejection phase shortening.

METHODS

Fourteen open chest anaesthetised dogs were used for the studies. After destruction of the sinus node, the heart was atrially paced and atrial extrasystoles were introduced followed by a short (400 ms) or long (700 ms) postextrasystole. The left anterior descending coronary artery was occluded for 5 min and reperfused for 10 min a total of eight times to produce stunned myocardium, followed by a final 60 min of reflow. Regional function was assessed with segment length sonomicrometers.

RESULTS

With successive periods of occlusion there was an increase in the end diastolic segment length and a progressive decrease in total percent systolic shortening (baseline 22.3%, 1st reflow 14.5%, 8th reflow 7.9%) with some recovery after 60 min of reflow (12.0%). This was predominantly due to the development of bulging during isovolumetric systole (4.5%, -4.9%, and -8.3%, respectively) which diminished during 60 min recovery to -3.1%. Ejection shortening was relatively constant (17.8%, 19.4%, 16.3%, and 15.1%, respectively). Postextrasystolic potentiation resulted in an increased in total percent systolic shortening, but not to the baseline value, as slight isovolumetric bulging persisted. Similar changes were seen with the short and long postextrasystoles although the latter had a greater increase in ejection shortening.

CONCLUSIONS

The decrease in function after repetitive occlusion and reflow is predominantly due to bulging during isovolumetric systole which persists after postextrasystolic potentiation in our model of stunned myocardium.

Assessment of coronary artery disease using single-photon emission computed tomography with thallium-201 during adenosine-induced coronary hyperemia

Thallium-201 myocardial imaging during dipyridamole-induced coronary hyperemia has been an accepted method for diagnosing coronary artery disease (CAD) and risk stratification. Adenosine is a powerful short-acting coronary vasodilator. Initial results of thallium imaging during adenosine infusion have been encouraging. In 132 patients with CAD and in 16 patients with normal coronary angiograms, adenosine was given intravenously at a dose of 0.14 mg/kg/min for 6 minutes and thallium-201 was injected at 3 minutes. The thallium images using single-photon emission computed tomography were abnormal in 47 of the 54 patients (87%) with 1-vessel, in 34 of 37 patients (92%) with 2-vessel and in 40 of 41 patients (98%) with 3-vessel CAD. The sensitivity was 92% in the 132 patients with CAD (95% confidence intervals, 86 to 96%). In patients with normal coronary angiograms, 14 of 16 patients had normal thallium images (specificity, 88%; 95% confidence intervals, 59 to 100%). The results were very similar when subgroups of patients were analyzed: those without prior myocardial infarction, elderly patients and women. The nature of the perfusion defects (fixed or reversible) was assessed in relation to whether the 4-hour delayed images were obtained with or without the reinjection technique. In patients who underwent conventional delayed imaging, there were more fixed perfusion defects than in patients with reinjection delayed imaging (16 vs 0%, p less than 0.0001). The adverse effects were mild, transient and well tolerated. Thus, adenosine thallium tomographic imaging provides a high degree of accuracy in the diagnosis of CAD. The use of the reinjection technique enhances the ability to detect reversible defects.

Managing angina in the elderly: an update

Angina pectoris in the elderly is usually due to fixed coronary arteriosclerotic disease. Management includes the use of nitrates and beta- and calcium-blocking drugs. A combination of these drugs may be necessary in patients with severe symptoms. Each of these drugs has potential side effects. These drugs should be started in small dosages and gradually increased, determined by the patient's response. Angina with associated disease states should determine what specific drugs are selected.

The role of nitrates, beta blockers, and calcium antagonists in stable angina pectoris

Numerous controlled studies have shown that nitrates, beta blockers, and calcium antagonists are effective in the treatment of stable angina pectoris. The pharmacokinetics, pharmacodynamics, and hemodynamic effects of these agents are different, and thus combination therapy offers additive improvement and also counterbalancing of the undesirable side effects of each drug. The choice of therapy depends on the severity of symptoms, associated diseases, compliance, side effects, and status of left ventricular function. The main mechanism of improvement is a decrease in myocardial oxygen consumption, though an increase in coronary blood flow is another potential reason for the use of calcium blockers. This review considers the properties of these drugs, their mechanism of action, and the results of randomized studies.

Dipyridamole cardiac imaging

Dipyridamole cardiac imaging is a useful alternative technique to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole is still in the investigational phase, while oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow (due to coronary vasodilation) which is in excess of the increase in myocardial oxygen consumption and cardiac output. The disparity in the increase in coronary blood flow relative to the cardiac output results in an increase in myocardial thallium activity and an increase in the myocardial/background activity ratio. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg, and of the oral dose it is 300 to 400 mg, although higher doses may be necessary in some patients. Analysis of the thallium images has been to a large extent based on visual inspection of the planar images. Delayed images are helpful to establish the nature of the perfusion abnormalities (transient or fixed). The process of redistribution is based on disparate rates of washout from the normal and abnormal zones. The sensitivity and specificity of dipyridamole thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole two-dimensional echocardiography has also been used in the detection of coronary artery disease; transient (new or worsening of preexisting) wall motion abnormalities have been found to be a specific marker of coronary artery disease. Transmural as well as regional coronary steal phenomena have been postulated as the mechanism for dipyridamole-induced regional wall motion abnormalities. Compared to exercise two-dimensional echocardiography, dipyridamole echocardiography provides high-quality studies and in higher proportions of patients. The results of dipyridamole thallium imaging have also been extremely important in identifying high-risk patients after acute myocardial infarction or patients with peripheral vascular disease undergoing elective vascular surgery; the presence of a dipyridamole-induced perfusion abnormality identifies patients at high risk for future cardiac events. Thus, dipyridamole cardiac imaging is helpful in the diagnosis of coronary artery disease and in risk stratification.

Use of exercise thallium-201 imaging for risk stratification of elderly patients with coronary artery disease

Although coronary artery disease (CAD) may be asymptomatic, it is the most common cause of death in elderly patients in the U.S. This study examined the prognosis of 449 patients with a mean age of 65 years using exercise thallium-201 imaging. At a follow-up of 25 months, 45 patients underwent coronary artery revascularization, 8 died of cardiac causes and 10 had nonfatal acute myocardial infarctions (AMIs). Thus the total of patients with "hard" events was 18. The events included 12 of 276 patients with atypical or non-anginal symptoms versus 6 of 128 with typical angina (p = not significant); 7 of 51 patients (14%) with Q-wave AMI versus 11 of 353 (3%) without Q-wave AMI (p less than 0.001); 1 of 183 patients (1%) with normal versus 17 of 221 (8%) with abnormal exercise thallium-201 images (p less than 0.002); 10 of 76 patients (13%) with multi vessel thallium-201 abnormality vs 8 of 328 (2%) with no or 1-vessel thallium-201 abnormality (p less than 0.001) and 10 of 96 patients (10%) with greater than or equal to 3 abnormal segments by thallium-201 imaging (total segments = 9) versus 8 of 308 patients with no or less than 3 abnormal segments (p less than 0.001). The number of segments with thallium-201 defects was 1 +/- 2 patients without and 3 +/- 2 in patients with hard events (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Thallium imaging with single photon emission computed tomography

Evaluation of myocardial perfusion with thallium-201 SPECT has advantages over planar images. These advantages are related to better contrast of the images, lack of superimposition of normal and abnormal areas, and a three-dimensional representation of the site and extent of perfusion abnormalities (ischemia, scar, or both). For this reason, rotational tomography is superior to planar imaging in assessing the extent of coronary artery disease, in the detection of small infarcts, and for quantitative measurements. Several techniques have provided accurate quantitative data for infarct sizing both in animals and men. The ability to quantitate infarct size (or ischemia) will be extremely important in studies of myocardial salvage, risk stratification, and longitudinal studies to evaluate the effects of medical and surgical interventions.

Role of exercise thallium 201 imaging in decision making

This prospective study examined the impact of results of exercise thallium 201 imaging on the estimation of probability of coronary artery disease (CAD) and patient management among cardiologists and internists in our institution. Before exercise testing, the probability of CAD in the 100 patients enrolled in this study was considered low in 31, intermediate in 28, and high in 41 patients. The probability of CAD after exercise thallium imaging was different in four patients (10%) in the high group, 22 patients (79%) in the intermediate group, and three patients (10%) in the low group. Further, the results of exercise testing resulted in changes in patient management in 29 patients (71%) in the high group, 26 patients (93%) in the intermediate group, and 16 patients (52%) in the low group. Overall, the management changed in 71% of the patients. This change included changes in medications, physical activity, frequency of office visits, need for cardiac catheterization, and need for coronary arterial bypass grafting. Thus, exercise thallium imaging is useful in clinical decision making: the diagnostic certainty is improved in patients with intermediate pretest probability of CAD; and some degree of change in patient management is observed, even in patients in whom the probability of CAD is not altered.