The nature of the background in radionuclide ventriculography: deductions from the mathematical behaviour of the ejection fraction.

The relationship between the ejection fractions calculated from 'uncorrected' radionuclide time activity curves (UEF) and angiographic ejection fractions (AEF) in 200 catheterized patients yielded the regression equation AEF = 1.74 UEF + 0.21.

Asymmetric distribution of left ventricular asynergy in coronary artery disease and its relation to coronary stenoses.

In 100 patients with coronary artery disease (CAD), the prevalence and severity of asynergy was determined for 9 left ventricular (LV) segments by both radionuclide and contrast angiography. The anterior, septal and lateral LV walls had significantly more prevalent and more severe asynergy in the medial segments than in the basal segments. In contrast, the inferior LV wall exhibited equally severe asynergy in both the medial and basal segments.

No increase in serum digoxin concentration with high-dose diltiazem.

The effect of incremental diltiazem dosing during concomitant digoxin administration over a four-week period in eight healthy adult volunteers (mean age, 28 +/- 4 years) was studied. The study group received 0.25 mg of digoxin twice daily for two days, after which they received 0.

Prevalence and severity of circumflex coronary artery disease in electrocardiographic posterior myocardial infarction.

To determine the coronary anatomy responsible for electrocardiographic posterior myocardial infarction, the prevalence and severity of disease in the right coronary and left circumflex coronary arteries were compared in 21 patients with electrocardiographic posterior infarction (17 of whom had associated inferior infarction) and 23 patients with isolated electrocardiographic inferior infarction. Significant circumflex coronary artery disease (greater than or equal to 75% stenosis) was more prevalent in patients with posterior or inferoposterior infarction (17 of 21) than in those with isolated inferior infarction (11 of 23) (p less than 0.02).

Beneficial effects of high-dose diltiazem in patients with persistent effort angina on beta-blockers and nitrates: a randomized, double-blind, placebo-controlled cross-over study.

The effects of orally administered diltiazem combined with maximally tolerated doses of beta-blockers and nitrates were assessed in 12 patients, who during stress testing exhibited persistent effort angina and continued objective evidence for inducible myocardial ischemia. Patients performed multistage semisupine exercise on a bicycle ergometer during equilibrium-gated radionuclide angiography after consecutive 2 week treatment periods of placebo or diltiazem 90 mg qid (mean dose 340 mg/day) combined with maximally tolerated propranolol (mean dose 178 mg/day) and isosorbide dinitrate (mean dose 137 mg/day). All medications (including diltiazem or placebo) were administered four times daily for the duration of the study.

Nifedipine-induced hypotension and myocardial ischemia in refractory angina pectoris.

Combined nitrate/beta-blocker/nifedipine therapy is commonly used to treat refractory angina pectoris. We have observed "paradoxical" myocardial ischemia in ten patients with refractory angina (seven receiving combined beta-blocker and nitrate therapy, and three receiving nitrate treatment alone) in whom nifedipine (mean dosage, 92 mg/day; range, 60 to 120 mg/day) induced a decrease in blood pressure, angina pectoris (10/10 patients), and ischemic ECG changes (7/10 patients). These ten patients, all of whom regularly reported angina within 20 to 30 minutes of nifedipine ingestion, were prospectively studied before and after usual nifedipine dose administration, while blood pressures, heart rate, and ECGs were recorded.

Inferoseptal myocardial infarction: another cause of precordial ST-segment depression in transmural inferior wall myocardial infarction?

Electrocardiographic ST-segment depression in the anterior precordial leads is a frequent observation during the initial hospital phase of acute transmural inferior myocardial infarction (MI), but is of uncertain significance. No available clinical studies have examined the prevalence of inferoseptal necrosis complicating inferior MI. Therefore, the clinical course, electrocardiographic features, radionuclide angiograms and cardiac enzyme changes in 57 patients with transmural inferior MI who did not have prior anterior or concomitant "true posterior" MI, associated anterior or posterolateral asynergy by radionuclide ventriculography, or left or right bundle branch block were reviewed retrospectively.

Left ventricular asynergy in electrocardiographic "posterior" myocardial infarction.

P2 300 selected patients, scalar electrocardiograms and contemporaneous radionuclide angiograms were analyzed retrospectively to assess the association between prominent right precordial R waves (duration greater than or equal to 0.04 second, R greater than or equal to S in lead V1 or V2), traditionally considered diagnostic of "posterior" infarction, and asynergy in various left ventricular segments. Mathematical methods for analysis of association between nonparametric variables clearly demonstrated that prominent right precordial R waves were strongly associated with asynergy of the basal lateral left ventricular wall, although asynergy of adjacent inferior and lateral segments was common.

Unstable angina with episodic ST segment elevation and minimal creatine kinase release culminating in extensive, recurrent infarction.

The syndrome of episodic angina at rest, recurrent ST segment elevation (mean = 9 mV) and nontransmural infarction characterized by minimal serum creatine kinase (CK) (mean 243 IU; upper normal limit 132 IU) was studied in 15 patients who presented with these findings. All were initially managed with intensive nitrate and beta-receptor blocker therapy. Eleven patients underwent intraaortic balloon counterpulsation for refractory angina and 13 underwent cardiac catheterization.

Calculation of the left ventricular ejection fraction by gated radionuclide angiography without direct background correction.

The mathematical characteristics of the cardiac background were studied in 50 patients who underwent both gated radionuclide angiography and cardiac catheterization. The background-corrected ejection fraction (BCEF) was calculated in the standard manner using an operator-defined periventricular background region. The "uncorrected" ejection fraction (UEF) was calculated from the uncorrected left ventricular time-activity curve and compared to both the BCEF and the angiographic ejection fraction (AEF), UEF exhibited remarkable linear correlation with both BCEF and AEF.

Hemodynamic correlates of right ventricular ejection fraction measured with gated radionuclide angiography.

Right ventricular function was studied in 60 patients with equilibrium gated radionuclide angiography. The mean (+/- standard deviation) right ventricular ejection fraction in 20 normal subjects was 53 +/- 6 percent, a value in agreement with previous data from both radionuclide and contrast angiographic studies. This value was similar (55 +/- 7 percent) in 11 patients with coronary artery disease but normal left ventricular function.

Measurement of normal left atrial function with gated radionuclide angiography.

A method is described for measuring relative left atrial volume changes with gated radionuclide angiography, using an approximate computer-generated functional image to locate the atrial region of interest. M mode echocardiographic measurements of left atrial and left ventricular distances from the chest wall allowed calculation of a correction factor for the differential attenuation of atrial and ventricular photons. Background-corrected left atrial time-activity curves obtained from normal subjects exhibited excellent temporal resolution and were used to identify and quantitate the reservoir and contractile phases of left atrial volume change.

Exercise-induced coronary spasm with S-T segment depression and normal coronary arteriography.

The unique association of both exercise-induced coronary arterial spasm and S-T segment depression with normal findings on selective coronary arteriography is described. The patient had a prior history of typical effort angina that had recently progressed to angina at rest. Despite the change in anginal pattern, the electrocardiogram disclosed S-T segment depression that was consistent with subendocardial ischemia, during both exercise testing and spontaneous chest pain.

Measurement of the ventricular stroke volume ratio by gated radionuclide angiography.

The ventricular stroke volume ratio or VSVR (left/right) was measured by gated radionuclide angiography in 33 normal subjects, using a 30 degree caudal slant-hole collimator and computer-generated functional images to aid in definition of the right ventricle. The mean ratio was found to be 1.06 +/- 0.

Tricuspid valve replacement for cardiogenic shock after acute right ventricular infarction.

A 66-year-old man had an acute inferior wall myocardial infarction complicated by hypotension, high-grade atrioventricular block, and distended neck veins, suggesting associated right ventricular infarction. He failed to respond to volume loading, intra-aortic balloon counterpulsation, and pharmacologic afterload reduction. Cardiac catheterization five days after the infarction disclosed severe tricuspid regurgitation and a hemodynamic pattern resembling pericardial constriction.

Gated radionuclide angiographic evaluation of valve regurgitation.

Gated radionuclide angiography is a new noninvasive technique that can be used to calculate the ratio of left and right ventricular stroke volumes. This stroke volume ratio, which must be unity in normal subjects, increases in patients with aortic or mitral regurgitation in direct proportion to the degree of left ventricular volume overload, provided no shunts or regurgitant right heart lesions are present. In 22 patients with aortic or mitral regurgitation there was excellent correlation between the stroke volume ratio determined with gated radionuclide angiography and with standard quantitative catheterization methods (r = 0.

Myocardial function in hypothyroidism. Relation to disease severity and response to treatment.

Systolic time intervals (ST) were used to evaluate myocardial function prospectively in 29 hypothyroid patients. The patients were divided into three categories of disease severity: (1) severe hypothyroidism, (2) mild hypothyroidism, and (3) decreased thyroid reserve or "prehypothyroidism." Groups 1 and 2 showed decreased myocardial contractility with a prolonged preejection period (PEP), shortened left ventricular ejection time (LVET), and increase PEP/LVET, compared with normal controls.

Cardiovascular responses to upper gastrointestinal endoscopy.

Continuous Holter monitoring and serial blood pressure recordings were obtained during upper gastrointestinal endoscopy on 51 unselected patients, 18 with cardiovascular disease. Sedation with intravenous diazepam produced a small but significant fall (P is less than .001) in blood pressure, heart rate and rate-pressure product.

Noninvasive evaluation of cardiac function in hypothyroidism. Response to gradual thyroxine replacement.

Left ventricular performance was studied in 15 patients with severe, primary hypothyroidism (mean serum total thyroxine of 0.8 mug per 100 ml and serum thyrotropin of 160 muU per milliliter). Pretreatment systolic-time intervals were characterized by prolongation of the pre-ejection period (delta PEP = +30) and reduction of the left ventricular ejection period (delta LVET = -23) with a resultant increase in the PEP/LVET ratio (0.