John Yiannikas

Cardiac cinefluoroscopy as an inexpensive aid in the diagnosis of coronary artery disease.

To compare the accuracy of cinefluoroscopy, exercise electrocardiography and thallium perfusion imaging in diagnosing coronary artery disease (CAD), these 3 studies were performed in 297 subjects without prior acute myocardial infarction who were referred for coronary angiography. Of the 137 patients who had more than 50% angiographic diameter narrowing in at least 1 major coronary artery, 91 (67%) were correctly identified by cinefluoroscopy, 90 (66%) by stress electrocardiography and 100 (73%) by thallium imaging. Of the 164 patients with no more than 50% diameter narrowing, the proportion of patients correctly identified as normal were 81%, 72% and 79%, respectively. Cardiac cinefluoroscopy correctly classified 74% of the 297 subjects as to their disease status (more than 50% coronary narrowing), compared to 69% for stress electrocardiography and 76% for thallium imaging. There was no significant difference between the sensitivity or specificity of the test combination of stress electrocardiography and cinefluoroscopy and the combination of stress electrocardiography and thallium imaging. Cardiac cinefluoroscopy, a relatively cost-effective diagnostic test, is similar in accuracy to other, more expensive noninvasive diagnostic examinations for CAD.

Variant Angina: Comparison of Patients With and Without Fixed Severe Coronary Artery Disease

To determine if the clinical features of variant angina are predictive of the severity of underlying coronary artery disease, 43 patients with variant angina who had less than 50% fixed coronary luminal diameter narrowing (group 1) were compared with 65 patients with variant angina who had 70% or greater diameter narrowing (group 2). Statistically significant differences were found in 3 clinical features between group 1 and group 2: (1) a more than 3-month history of angina at rest before diagnosis (80% vs 23%, p less than 0.001); (2) an abnormal electrocardiogram at rest (19 vs 48%, p less than 0.01); and (3) an abnormal stress test (26% [8 of 30] vs 84% [15 of 18], p less than 0.01). However, these features were not clinically reliable in separating patients with variant angina with and without fixed severe obstructions because of overlap between the 2 groups. No difference was found between the 2 groups in age, sex, predominant symptom at the time of catheterization, history of exertional angina, syncope with angina, prolonged angina, previous myocardial infarction or risk factors for coronary artery disease. There was also no difference in the location of ST elevation or occurrence of major arrhythmias during angina. Thus, among patients with Prinzmetals variant angina, those with normal or mildly abnormal coronary arteriograms cannot be differentiated reliably by clinical features from those with fixed severe coronary obstructions. Coronary arteriography should be performed to define the underlying coronary anatomy and to determine optimal therapy in patients with variant angina.

Prediction of improvement in left ventricular function after ventricular aneurysmectomy using fourier phase and amplitude analysis of radionuclide cardiac blood pool scans

Postoperative improvement in left ventricular (LV) function is a common objective of LV aneurysmectomy, but is difficult to predict. The first Fourier component of time-activity curves of pre- and postoperative gated radionuclide angiographic studies was evaluated for this purpose in 20 patients who had undergone aneurysmectomy. LV aneurysms had portions that characteristically exhibited marked phase delay with varying degrees of amplitude. Total aneurysmal amplitude was obtained preoperatively by summing the amplitude component of all pixels that exhibited phase delay, suggesting paradoxical motion. LV ejection fraction (EF) before and after aneurysmectomy and the absolute postoperative increase in LVEF were calculated. Nine of 20 patients had an absolute increase of EF less than 10% despite resection of large aneurysms. A strong correlation was found between the absolute increase in EF after aneurysmectomy and the total amplitude within paradoxically moving areas (r = 0.93, p less than 0.0001). Thus, preoperative measurement of the total paradoxical amplitude predicts absolute change in EF and may be important in selecting patients for aneurysmectomy. The data also suggest that the total aneurysmal amplitude reflects the stroke volume ejected into an aneurysm in systole and that paradoxical expansion of an aneurysm contributes to LV dysfunction in some of these patients.

Intravenous digital subtraction angiography in the assessment of patients with left to right shunts before and after surgical correction

Pre- and postoperative structural changes and pulmonary to systemic flow (QP/QS) ratios were assessed using digital angiography in 34 patients documented to have a left to right shunt at cardiac catheterization. There were 16 men and 18 women whose ages ranged from 4 months to 60 years. The radiographic single mask mode was used for all digital subtraction angiographic studies with a typical radiographic sequence being 80 to 100 kV, 5 to 10 mA/frame at six frames/s for 15 seconds. Renografin-76 was used as a bolus injection at 0.5 to 1.0 ml/kg via an arm vein in most patients. The level of the left to right shunt and any associated anomalies were noted and compared with results from cardiac catheterization. Digital subtraction angiographic flow curves were generated from the pulmonary arteries, and QP/QS ratios were calculated pre- and postoperatively using the gamma variate fit method and compared with the QP/QS ratio from first pass radionuclide studies. A strong correlation between preoperative digital subtraction angiographically derived QP/QS ratio and radionuclide-derived QP/QS ratio was found, with an r value equal to 0.89, p less than 0.0001. Postoperatively, all patients had a QP/QS ratio less than 1.2:1.0 for both digital subtraction angiography and radionuclide studies. The level of left to right shunt was accurately assessed in all patients, and its absence observed postoperatively. Associated anomalies, such as a persistent left superior vena cava, coarctation of the aorta and partial anomalous venous return, were identified in all cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Verification of Fourier phase and amplitude values from simulated heart motion using a hydrodynamic cardiac model

Using pusher-plate-type artificial hearts, changes in the degree of synchrony and stroke volume were compared to phase and amplitude calculations from the first Fourier component of individual-pixel time-activity curves generated from gated radionuclide images (RNA) of these hearts. In addition, the ability of Fourier analysis to quantify paradoxical volume shifts was tested using a ventricular aneurysm model by which the Fourier amplitude was correlated to known increments of paradoxical volume. Predetermined phase-angle differences (incremental increases in asynchrony) and the mean phase-angle difference calculated from RNAs showed an agreement of -7°±4.4° (mean ±SD). A strong correlation was noted between stroke volume and Fourier amplitude (r=0.98; P<0.0001) as well as between the paradoxical volume accepted by the ‘aneurysm’ and the Fourier amplitude (r=0.97; P<0.0001). The degree of asynchrony and changes in stroke volume were accurately reflected by the Fourier phase and amplitude values, respectively. In the specific case of ventricular aneurysms, the data demonstrate that using this method, the paradoxically moving areas may be localized, and the expansile volume within these regions can be quantified.

The Use of Intravenous Digital Subtraction Angiography in the Evaluation of Tetralogy of Fallot

Sixteen patients with tetralogy of Fallot were studied with intravenous digital subtraction angiography (DSA). Of these, 11 were males and five were females, ranging in age from 26 months to 54 years, with a mean age of 22 years at the time of the initial study. Twenty-two DSA studies were performed in the 16 patients, in seven patients preoperatively, in 12 patients postoperatively, and in three patients both pre- and postoperatively. In the seven patients studied preoperatively, all DSA studies were considered technically adequate as corroborative evidence in the diagnosis of tetralogy of Fallot. All associated cardiac abnormalities were adequately demonstrated. The 16 postoperative studies on 12 patients were performed to evaluate the adequacy of the surgery and/or postoperative complications. These studies were judged as technically satisfactory. The authors utilized intravenous DSA in the pre- and postoperative evaluation of 16 patients with tetralogy of Fallot and found that reliable angiographic information was provided and that this technique may serve as a useful adjunct with other noninvasive and invasive tests in the preoperative and postoperative evaluation of these patients.