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Clin. Cardiol. 23, 557–558 (2000)
Key words: ventricular function, angiography, echocardiography, radionuclides, magentic resonance angiography
Prognosis of most patients with cardiac disease is related to left ventricular function. This was shown clearly in reports of the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) angiographic substudy, the Gruppo Italiano per lo Studio della Sopravvivenza nell' Infarto miocardico (GISSI) trial, and a trial in which ventricular function was determined by echocardiography in patients with unstable angina.1–3 When ventricular function is determined by any method, it provides a snapshot at one point in time indicating what might happen in the future. Obviously, assessment of ventricular function at another point in time might show improvement or deterioration and further refine the prognostic implications of the assessment. Thus, ideally, it would be useful to have a method that can be repeated, costs little, and is not potentially harmful to the patient.
All clinicians rely on the physical examination, chest x-ray, and electrocardiogram when assessing ventricular function in cardiac patients. A patient who is hypotensive, tachycardic, has distended neck veins, peripheral edema, rales in the chest, a third heart sound, an apex impulse in the anterior axillary line, cardiomegaly and pulmonary venous congestion on chest x-ray, and Q-waves from V1 to V6 on the electrocardiogram obviously will have poor ventricular function by any method used; but any one of the above findings taken out of context may not have anything to do with ventricular dysfunction. Thus, quantification of ventricular function may not be possible in the usual stable cardiac patient, but it certainly is repeatable, inexpensive, and does not harm the patient.
As someone who was trained in the catheterization laboratory, I tend to think of ventricular function as a combination assessment of ventricular pressure and ventricular angiography. Unfortunately, this is a snapshot of ventricular performance in systole and diastole that is not readily repeatable, may endanger the patient, and certainly is not inexpensive. In addition, the majority of ventriculograms are in the right anterior oblique projection, thus allowing assessment of the anterior wall, apex, and inferior wall of the heart. The septum and lateral wall are not seen unless biplane angiography is performed. Because the contrast must be injected with high pressure and flow, sinus rhythm is often not accomplished. Hibernating or ischemic myocardium can be identified with some degree of accuracy by repeating the ventriculogram after infusing glycerol trinitrate, following a premature ventricular contraction, or by infusing an inotrope such as dobutamine. This, however does add some additional risk to the procedure since additional radio opaque contrast must be given to the patient, perhaps increasing the incidence of contrast-induced renal dysfunction.
Radionuclide angiography does provide an assessment of global ventricular function (ejection fraction) and is readily available, but because it is not inexpensive and there is an exposure to radioactive tracers, it is not readily repeatable. In addition, very little information about diastolic function of the ventricle is obtained from radionuclide studies. One can, however, exercise the patient or stimulate the ventricle with inotropic and chronotropic agents in order to provoke ischemic changes and assess ventricular function under conditions stressing the heart.4 Right ventricular function can also be assessed using radionuclide ventriculography. Obviously, this technique does not provide pressure measurements or assessment of valve function.
Magnetic resonance angiography provides an excellent picture of the ventricle in systole and diastole (if gated), but regional wall motion abnormalities are more difficult to visualize. In addition, there are no pressure measurements and no assessment of valve function. Although noninvasive and repeatable, magnetic resonance angiography will not be repeated very often because of the expense and relative unavailability of the technique. Diastolic function is not assessed and inotropic or chronotropic stimulation may be difficult to accomplish. Exercise studies cannot be done.
Cine magnetic resonance angiography will provide an excellent assessment of left ventricular function, right ventricular function, and valve function and can be accomplished in sinus rhythm. However, ventricular pressure is not measured. This technique is not readily available, therefore not readily repeatable, and it is not inexpensive. Diastolic function can be assessed but it is not easy to stimulate the patient with inotropic and chronotropic drugs. Exercise studies cannot be done.
Cardiac ultrasound provides information on left ventricular systolic (ejection fraction and wall motion score index) and diastolic function (Doppler) in sinus rhythm. Left ventricular size, end-systolic and end-diastolic dimension, left ventricular shape, presence or absence of aneurysm, and left ventricular septal and lateral wall motion and integrity of the septum (ventricular septal defect) can be evaluated. Valve function, including mitral, tricuspid, aortic, and pulmonic valves, as well as chordae tendineae and papillary muscles, are easily assessed with this technique. Right ventricular size, shape, and contraction patterns can be evaluated in, for example, patients with right ventricular infarction and so forth. Ventricular end-diastolic pressure can be estimated. This technique is readily available, repeatable, relatively inexpensive, and patients can be exercised or stimulated with inotropic or chronotropic agents to assess performance under these conditions.
It seems to me that when evaluating ventricular function in cardiac patients the best buys for the money are the combination of physical examination, chest x-ray, electrocardiogram, and cardiac ultrasound. Opponents will argue that adequate images of the heart using cardiac ultrasound cannot be obtained in all patients undergoing assessment of ventricular function. Most ultrasonographers used to agree with this assessment, but modern equipment using harmonic imaging and contrast echocardiography makes that argument less plausible. At the moment, in patients with a recent myocardial infarction, I find cardiac ultrasound to be the most useful test for assessment of ventricular function and thus for risk stratification of the patient in the immediate postinfarction state, that is, within 24 h. Assessment can be made regardless of the stability of the patient at the time of this assessment.
| Table I Summary of various aspects of the different methods used to evaluate ventricular function (see text for details) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
Pressure LV EDP
|
Valve gradients
|
Diastolic function
|
RV function
|
Global function
|
Sinus rhythm
|
Exercise stress
|
Inotropic stress
|
Readily available
|
Easily repeatable
|
Inexpensive
|
Noninvasive
|
| Physical exam |
+/2 (1)
|
+
|
+/2 (2)
|
+/2 (3)
|
+/2
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
| Chest x-ray |
+/2 (4)
|
+/2 (5)
|
2
|
2
|
+/2 (6)
|
+
|
2
|
2
|
+
|
+
|
+
|
+
|
| ECG |
+/2 (7)
|
2
|
2
|
2
|
+/2 (8)
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
| Hemodynamics |
+
|
+
|
+
|
+
|
+/2
|
+
|
+
|
+
|
+
|
2
|
2
|
2
|
| Angiography |
2
|
2
|
2
|
2
|
+
|
+/2
|
2
|
+
|
+
|
2
|
2
|
2
|
| Radionuclide |
2
|
2
|
2
|
+
|
+
|
+
|
+
|
+
|
+
|
2
|
2
|
2
|
| MRA |
2
|
2
|
2
|
+
|
+
|
+
|
2
|
2
|
2
|
+
|
+/2
|
+
|
| Cine MRA |
2
|
+/2
|
+/2
|
+
|
+
|
+
|
2
|
2
|
2
|
+
|
+/2
|
+
|
| Ultrasound |
+/2
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
+
|
| (1) = Pulmonary rales, (2) = S4, (3) = parasternal lift, (4) = pulmonary edema, (5) = calcium, (6) = cardiomegaly, (7) = negative pV1, (8) = Q-waves. | ||||||||||||
| Abbreviations: LV EDP = left ventricular end-diastolic pressure, RV = right ventricular, ECG = electrocardiogram, MRA = magnetic resonance angiography. | ||||||||||||
C. Richard Conti, M.D., M.A.C.C.
Editor-in-Chief