Radionuclide Angiograms Research Articles

Utility of Equilibrium Radionuclide Angiogram-Derived Measures of Dyssynchrony to Predict Outcomes in Heart Failure Patients Undergoing Cardiac Resynchronization Therapy.

Sixty-six advanced heart failure patients referred for CRT with an LV ejection fraction (EF) of < 35% and QRS ≥ 120 ms were studied. We performed equilibrium radionuclide angiography (ERNA) before and 6 mo after CRT. We assessed ventricular dyssynchrony with parameters derived from the first harmonic phase (Ø) analysis of the ERNA time-activity curve and evaluated change in these parameters after 6 mo of CRT. These parameters include novel indices of synchrony (S), a measure of intraventricular contraction order, and entropy (E), a measure of intraventricular contraction disorder, and interventricular synchrony (IVS), a measure of synchronous biventricular function. Forty-seven (71%) patients improved clinically (responders) at 6 mo after CRT whereas 19 (28.8%) showed no change in New York Heart Association class or worsened (nonresponders). The post-CRT changes in QRS duration (P = 0.006), echocardiographic (P = 0.03) and ERNA LVEF (P = 0.0007), LVS (P = 0.004), LVE (P = 0.006), LV standard deviation of ventricular phase (LVSDØ) (P = 0.004), and IVS (P = 0.05) were significantly different between responders and nonresponders. Sixty-two percent of responders had either an LVS < 0.84 or an IVS ≥ 18.8° as opposed to only 16% of nonresponders (P = 0.001). Twenty-nine of 32 (91%) patients with either of these measures responded to CRT (P < 0.01). LVS and IVS are novel measures of LV dyssynchrony derived from ERNA planar analysis. A baseline value of LVS < 0.84 or IVS ≥ 18.8° predicts a positive response to CRT.

Should ancillary brain blood flow analyses play a larger role in the neurological determination of death?

We present two patients who regained spontaneous respiration following clinical neurological determination of death (NDD) while ancillary radiological imaging demonstrated brain blood flow. A 26-yr-old male with chronic otitis media presented with a Glasgow Coma Scale (GCS) score of 3 and fixed 7-mm pupils. Computed tomography demonstrated right-sided mastoiditis and a temporal lobe abscess associated with uncal herniation. The patient was diagnosed brain dead seven-hr later when motor responses and brainstem reflexes were absent and his apnea test was positive. Approximately 28-hr after NDD, during post-declaration organ resuscitation, the patient regained spontaneous respiration and magnetic resonance imaging revealed brain blood flow. Spontaneous respirations persisted for five-days before cardiovascular collapse occurred. In the second case, a 50-yr-old female presented with a GCS score of 3 and fixed 6-mm pupils following a traumatic brain injury and a five-minute cardiac arrest. The patient was deemed clinically brain dead six-hr later when physical examination revealed absent motor responses and brainstem reflexes and her apnea test was positive. As confirmation of brain death, a cerebral radionuclide angiogram was performed, which surprisingly revealed intracranial arterial flow. During organ resuscitation, 11-hr after NDD, the patient regained spontaneous respiration. She expired hours after family decision to withdraw treatment. For both patients, several unrecognized confounding factors for NDD were present. These cases illustrate the difficulties encountered by experienced clinicians in determining brain death using clinical criteria alone, and they suggest that more routine use of ancillary brain blood flow analyses should be recommended.

The effects of β-blockers in patients with stable chronic heart failure. Predictors of left ventricular ejection fraction improvement and impact on prognosis

Previous studies, with limited number of patients, have tried to determine the predictors of left ventricular ejection fraction (LVEF) improvement after beta-blockade. No study has demonstrated that LVEF improvement was an independent predictor of cardiac survival. The aims of the study were to determine in a large group of patients with stable chronic heart failure associated with reduced LVEF the predictors of LVEF improvement (difference in LVEF [deltaLVEF], ie, the value after beta-blockade minus the value before beta-blockade) after beta-blockade and to analyze prognostic impact of deltaLVEF. Three hundred fourteen consecutive patients underwent an echocardiogram, a radionuclide angiogram, and a maximum cardiopulmonary exercise test before and 3 months after maximal tolerated doses of beta-blockers have been reached. After beta-blockade, LVEF improved from 30% +/- 11% to 40% +/- 13%. In the whole population, independent predictors of deltaLVEF were nonischemic etiology, baseline LVEF (negative correlation), and baseline heart rate (positive correlation). In ischemic patients, independent predictors of deltaLVEF were absence of history of myocardial infarction, baseline heart rate, and baseline LVEF; whereas in nonischemic patients, independent predictors were baseline LVEF and baseline QRS width (negative correlation). After 1082 days of follow-up, there were 53 cardiovascular deaths and 2 urgent transplantations. Left ventricular ejection fraction improvement (defined as an absolute increase in LVEF > 5%) was an independent predictor of cardiac survival. Patients who had an LVEF < or = 45% after beta-blockade with a deltaLVEF < or = 5% represented a high-risk subgroup. In patients with chronic heart failure, predictors of LVEF improvement after beta-blockade were different according to etiology. Left ventricular ejection fraction improvement was an independent predictor of cardiac survival.

Positron emission tomography and recovery following revascularization (PARR-1): the importance of scar and the development of a prediction rule for the degree of recovery of left ventricular function

ObjectivesThe aim of this study was to determine whether the extent of viability or scar is important in the amount of recovery of left ventricular (LV) function, and to develop a model for predicting recovery after revascularization that could be tested in a randomized trial. BackgroundF-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) is used to define viable myocardium in patients with coronary artery disease (CAD) and severe LV dysfunction and to guide revascularization decisions. Whether this approach improves clinical outcomes has not been tested in a randomized trial. Before doing so, an objective model for prediction of recovery is required. MethodsA total of 82 patients with CAD and an ejection fraction (EF) ≤35% had FDG PET perfusion imaging before revascularization. Complete follow-up was available on 70 patients (86%). Patients had radionuclide angiograms at baseline and three months post-revascularization. ResultsDiabetes (p = 0.029), time to operation (p = 0.008), and scar score (p = 0.001) were significant independent predictors of the change in EF. Previous coronary artery bypass graft confounded the effect of age. There was a significant interaction between the perfusion tracer used and mismatch score (p = 0.02). The multivariable prediction model incorporating PET and clinical variables had a goodness of fit with p = 0.001. Across tertiles of scar scores (I, small: 0% to 16%; II, moderate: 16% to 27.5%; III, large: 27.5% to 47%), the changes in EFs were 9.0 ± 1.9%, 3.7 ± 1.6%, and 1.3 ± 1.5% (p = 0.003: I vs. III), respectively. ConclusionsIn patients with severe LV dysfunction, the amount of scar was a significant independent predictor of LV function recovery after revascularization. A combination of PET and clinical parameters predicts the degree of recovery. This model is being applied in a large randomized controlled trial to determine the effectiveness of therapy guided by FDG PET.

Twelve-year outcome of patients with an abnormal exercise radionuclide left ventricular angiogram and angiographically insignificant coronary artery disease

This study examines the long-term prognosis of patients with an abnormal exercise radionuclide angiogram in the absence of significant angiographic coronary artery disease (CAD). In general, patients without significant CAD have an excellent prognosis, but the long-term outcome for the subset of patients with an “ischemic” exercise test is not known. In this study, 161 patients with normal coronary arteries or insignificant CAD (<50% left main and <70% left anterior descending, left circumflex, or right), resting left ventricular (LV) ejection fraction ≥0.50, and an abnormal exercise radionuclide angiogram (LV ejection fraction that decreased with exercise or peak exercise LV ejection fraction <0.60) were followed for a median duration of 11.3 years. The mean Δ LV ejection fraction was −0.07, 98 patients (61%) had a decrease in LV ejection fraction of ≥5 units, and 40 patients (25%) had peak exercise LV ejection fraction <0.50. During follow-up there were 19 deaths (only 1 of which was cardiac), 7 nonfatal myocardial infarctions, and 9 revascularization procedures. At 12 years, overall survival was 88%, better than the expected survival for the age- and sex-matched general population. Survival free of cardiac death or myocardial infarction was 94% and survival free of any cardiac event including revascularization was 88%. Thus, patients with an abnormal exercise radionuclide angiogram but without significant CAD have an excellent long-term prognosis.

Reliability of enhanced gated SPECT in assessing wall motion of severely hypoperfused myocardium: Echocardiographic validation

Background. A method has been described for improving myocardial visibility on 99mTc-labeled labeled sestamibi gated tomograms, even in the presence of severe hypoperfusion. It is essential to verify that images transformed in this manner truly depict the myocardium and do not contain image artifacts. This is especially important if transformed images are to be used to aid in the discernment of regional wall-motion abnormalities. Methods and Results. All radially detected maximum counts were mapped automatically to the same brightness level for each cinematic frame. This produced tomographic cine images strongly suggestive of myocardium that appeared to translate but not to brighten from diastole to systole. Transformed scintigrams were compared with echocardiographic cine images of horizontal long axis and short axis views for 40 patients. Echocardiograms were of sufficient quality to allow comparison of radial distances from left ventricular center to midmyocardium for 15 short axis images and 25 horizontal long axis images. Readings were graded independently for 10 territories on a five-point scale (normal, mild-to-moderate hypokinesis, severe hypokinesis, akinesis, dyskinesis) of regional wall motion of original and enhanced scintigrams and echocardiograms. comparison of echocardiographic and single photon emission computed tomographic (SPECT) locations of midmyocardial horizontal long axis points yielded a root-mean-square error value of 1.5 ± 0.6 pixels (average absolute error, 11% ± 5%). SPECT versus echocardiographic wall-motion readings were compared by means of contingency table analysis. The log-likelihood ratio (G 2) was 109.3 ( n = 364; df = 16) with probability of no association <10 −6. Although readings of unenhanced SPECT cine images agreed well with those of echocardiograms (G 2 = 94.3; n = 350; df = 16; P < 10 −6), Pearson-corrected contingency coefficients indicated stronger association with echocardiograms of transformed tomograms than with readings of original scintigrams (0.57 versus 0.51). The McNemar χ 2 test indicated this improvement to be significant. The strongest associations were found between readings of unenhanced and enhanced scintigrams. Overall, similar results were obtained for horizontal long axis and short axis territories when analyzed separately. Linear regression analysis indicated strong correlations ( r = .80 to r = .92) of ejection fractions from unenhanced gated SPECT images, enhanced gated SPECT images, echocardiograms, and first-pass radionuclide angiograms with no significant differences among correlations. Conclusions. Regional image enhancement succeeded in revealing shapes that genuinely represented myocardium in this population with hypoperfusion. Wall-motion conclusions were similar whether drawn from original or enhanced scintigrams, although enhancement significantly improved agreement with echocardiographic readings. Enhanced SPECT cine images allowed sensitive discrimination of regional wall-motion abnormalities, even in areas of severely hypoperfused myocardium, in excellent agreement with visual echocardiographic assessment for which myocardial visualization is independent of perfusion.

Relation of Changes in Left Ventricular Peak Filling Rate During Exercise to Exercise Performance in Systemic Hypertension and in Healed Myocardial Infarction

Patients with systemic hypertension and coronary artery disease (CAD) often manifest abnormalities at rest in left ventricular (LV) diastolic function and reduced exercise tolerance. It is possible that abnormalities in filling persist during exercise and are partially related to abnormal exercise tolerance. We examined rest and exercise peak filling rate (PFR) to determine if changes in PFR during exercise influence exercise performance. We studied 20 patients with systemic hypertension who had no evidence of CAD (negative thallium-201 stress imaging) and 15 patients with prior myocardial infarction, preserved ejection fraction, and no ischemia by thallium-201 stress imaging. Results were compared with 20 normal subjects. All 55 subjects had rest and exercise radionuclide angiograms Peak workload, exercise time, and LV ejection fraction were reduced in subjects with CAD (57 ± 24 W, 7.41 ± 2.91 min, and 60 ± 9%) compared with subjects with hypertension (72 ± 21 W, 9.69 ± 3.03 min, and 70 ± 6%, p <0.05) and controls (80 ± 30 W, 10.82 ± 3.50 min, and 67 ± 6%, p <0.05). PFR at rest was reduced in CAD subjects (2.40 ± 0.70 end-diastolic volume per second [EDV/s]) compared with those with hypertension (2.89 ± 0.70 EDV/s, p <0.02) and controls (3.23 ± 0.52 EDV/s, p <0.0002). The increments in PFR during exercise were reduced in CAD patients (+1.76 ± 0.95 EDV/s) compared with hypertensive subjects (+2.93 ± 1.7 EDV/s) and controls (+3.22 ± 1.4 EDV/s, p <0.05). The increment in PFR during exercise was related to exercise performance (r = 0.49, p <0.0002). These findings suggest that alterations in LV diastolic filling during exercise are important determinants of exercise performance.

Global cardiac function using fast breath-hold MRI: validation of new acquisition and analysis techniques.

Calculation of global cardiac function parameters has been validated using fast, segmented k-space, breath-hold, gradient-echo, magnetic resonance images. Images of phantoms, experimental animals, normal volunteers, and patients were acquired with a 1.5 T clinical scanner. Humans were imaged using two phased-array surface coils in multicoil mode. Myocardial contours were extracted using a new interactive, semi-automated method based on the active contour model method. Images were acquired in the short-axis orientation, and, using a new imaging and analysis strategy, in rotating plane long-axis orientations, to provide better definition of the valve planes and the apex, and also to reduce the number of slices (compared with the short-axis method) required to sample the whole heart. Validation was accomplished through calculation of the volumes of phantoms and left and right ventricular masses of animal hearts. Functional parameters from MRI were compared with those from echocardiograms and radionuclide angiograms in normal volunteers and patients, respectively.

Anthracycline-induced cardiotoxicity in children with malignancies.

The anthracyclines (ATC) have been used in the treatment of many pediatric patients with malignancies. Their use, however, has been limited by a serious and potentially irreversible cardiotoxicity. The medical records of pediatric patients with malignancies who received ATC at the Department of Pediatrics, Kyushu University, from January 1985 to December 1994 were reviewed. Among the 120 children with malignancies who received ATC, six patients (5%) developed congestive heart failure, 33 (28%) had subclinical cardiac dysfunction, whereas 81 (66%) showed no evidence of cardiac dysfunction. The incidence of ATC cardiotoxicity increased at higher cumulative doses. The earliest cardiotoxicity, however, was observed in a patient who received 180 mg/m2 unassociated with other risk factors, showing the marked individual variations in its development. Children younger than 4 years had a higher incidence of cardiotoxicity compared with those older than 4 years (P < 0.01) and are therefore more vulnerable to ATC cardiotoxicity. Because serial myocardial biopsies and stress testing are not practical in younger children, and radionuclide angiogram is rather costly and not appropriate for frequent evaluation, non-invasive tests such as echocardiography and electrocardiography (ECG) still play the main role for serial cardiac monitoring in these age groups. Radionuclide angiogram should be added as the confirmatory test modality.

The role of radionuclide angiocardiography in the treatment of patients receiving doxorubicin-based chemotherapy: a reassessment.

We attempted to evaluate the role of radionuclide angiography in the routine treatment of patients receiving doxorubicin-based therapy in a university hospital setting. We identified 222 cancer patients treated with doxorubicin or who underwent radionuclide angiography with the intent to receive doxorubicin at the University of Iowa in 1989. We examined the cumulative doses of doxorubicin, results of radionuclide angiograms, cardiac risk factors, and clinical outcomes and survival of patients. Of 222 patients, 168 (76%) underwent at least one radionuclide angiogram and received doxorubicin. Only a baseline study was performed in 136 (81%) of these 168 patients. Only 32 underwent follow-up study during therapy; six patients discontinued therapy for an 11-21% decrease in left ventricular function. The mean dose of doxorubicin received was 211 mg/m2, and 193 patients (96%) received a cumulative dose <450 mg/m2. Only two patients (1%) had heart failure. A questionnaire sent to medical oncologists in Iowa showed that use of radionuclide angiography in our institution reflected practice throughout the state. The majority of patients in our population who underwent radionuclide angiography had a single baseline study, which provides little clinically useful information. The majority of patients receiving doxorubicin as currently employed can be safely treated without radionuclide angiography.

Usefulness of Serial Radionuclide Angiography in Predicting Cardiac Death After Coronary Artery Bypass Grafting and Comparison With Clinical and Cardiac Catheterization Data

This investigation assesses the prognostic value of radionuclide measurements of cardiac function in patients undergoing coronary artery bypass grafting (CABG). Radionuclide angiograms during exercise and at rest were obtained in 182 patients before (≤30 days), early (≤3 months), and late (≤3 years) after CABG. Cox proportional hazard regression analysis was used to identify independent predictors of 44 cardiac deaths that occurred a median 12 years after bypass. Although the exercise ejection fractions before and early after CABG were significantly related to subsequent cardiac death (chi-square = 10.84, p = 0.001, and chi-square = 7.4, p = 0.006, respectively), the late postoperative exercise ejection fraction was the strongest predictor (chi-square = 13.9, p = 0.0002), contributing above and beyond clinical and catheterization data. These data document the validity of the exercise ejection fraction as an important predictor of cardiac death after CABG and suggest the potential clinical application of serial measurements of the exercise ejection fraction as an important noninvasive adjunct to postoperative evaluation of these patients.Exercise ejection fractions before, early, and late after bypass were significantly related to cardiac death (chi-square = 10.84, p = 0.001; chi-square = 7.4, p = 0.006; and chi-square = 13.9, p = 0.0002, respectively). Moreover, peak exercise ejection fraction from the last radionuclide assessment contributed significant information beyond the clinical history or catheterization data (p = 0.0002).

Reproducibility of left ventricular size, shape and mass with echocardiography, magnetic resonance imaging and radionuclide angiography in patients with anterior wall infarction. A plea for core laboratories.

After myocardial infarction, left ventricular volume and ejection fraction can be assessed by echocardiography, magnetic resonance imaging and radionuclide angiography to guide therapy and determine prognosis. Whether a measured parameter gives the same results irrespective of the method used and the observer who performs the analysis is only partly known. Intra-observer and inter-observer variability were determined for echo and magnetic resonance imaging. Left ventricular ejection fraction measured by these techniques was related to radionuclide angiograms performed in the same period. Intra-observer variability for both echo and MRI was low and in most instances below 5%. Inter-observer variability for the echo and MRI measurements were substantially higher than intra-observer variability. Comparison of the three imaging modalities revealed systematic differences. Therefore, in clinical studies, left ventricular volume and function parameters have to be measured with the same technique and by the same observer in qualified core laboratories.

Antihypertensive treatment in hypertensive patients with normal left ventricular mass is associated with left ventricular remodeling and improved diastolic function

Antihypertensive therapy in hypertensive patients with left ventricular (LV) hypertrophy causes hypertrophy regression and improved diastolic filling. Whether similar changes occur in hypertensive patients with diastolic dysfunction and no hypertrophy is unknown. We determined the effect of antihypertensive therapy on LV geometry and function in hypertensive patients without hypertrophy. In 18 mild to moderate hypertensive patients without significant hypertrophy, baseline echocardiograms and rest and exercise radionuclide angiograms were performed. Subjects were treated for 8 to 12 months with the calcium channel blocker felodipine and then restudied 2 weeks after treatment withdrawal. Blood pressure normalized with treatment (165 ± 22/ 98 ± 9 to 128 ± 12/80 ± 5 mm Hg, p < 0.001) and returned to pretreatment levels after therapy withdrawal. Rest ejection fraction and peak oxygen consumption and cardiac outputs were unchanged after treatment, but rest peak filling rate increased (2.63 ± 0.57 to 3.11 ± 0.95 end-diastolic volume/second, p 0.05). Ejection fraction increased with exercise only after treatment (64 ± 5% at rest to 71 ± 8% at peak exercise, p < 0.05). LV mass index was unchanged (97 ± 18 to 101 ± 23 g/m 2), but relative wall thickness declined (0.41 ± 0.05 to 0.37 ± 0.05) and LV end-diastolic dimension increased (4.9 ± 0.4 to 5.2 ± 0.4, p = 0.01). Blood pressure control in hypertensive patients without hypertrophy leads to improved peak filling rates and remodeling with decreased relative wall thickness. Improved diastolic function can occur without alterations in LV mass.

A mural thrombus of an infrarenal aortic aneurysm demonstrated as photon deficiency in a radionuclide study.

Radionuclide angiogram (RNA) and aortogram may underestimate external aneurysmal diameter. Photon deficient areas are not uncommon along the abdominal aortic aneurysm (AAA) on RNA. To determine whether or not photon deficient areas along the aneurysm could represent a large thrombus, we studied radionuclide aortic angiography in thirty-eight patients during a preoperative cardiac gated study. All the patients (men, ages from 60 to 78) had CT, US, and/or aortogram for comparison. The presence of a thrombus was determined by CT, US, and/or surgical findings. Twelve of 38 (32%) patients' RNA and blood pool images showed photon deficient areas along the aneurysmal walls having a large concentric or eccentric thrombus of the AAA. A large photon deficient area could be detected along the narrowing calibre of the aorta lumen. This finding results from a large mural thrombus being interposed between the left or right bowel/mesentery activity and the activity of the aneurysms functioning patent lumen. We concluded that a photon deficient area along an inferorenal aortic aneurysm may indicate a large thrombus of either eccentric or concentric type within an AAA.

Use of a tantalum-178 generator and a multiwire gamma camera to study the effect of the Mueller maneuver on left ventricular performance: Comparison to hemodynamics and single photon emission computed tomography perfusion patterns

During the Mueller maneuver, there is a decrease in intrathoracic pressure and an increase in transmural left ventricular pressure. The changes in loading conditions cause transient left ventricular dysfunction. This study examined the effects of the Mueller maneuver on left ventricular performance using tantalum (Ta)-178 (half-life 9.3 min) and a multiwire gamma camera. First-pass radionuclide angiograms were obtained at baseline and during Mueller maneuver in 41 patients aged 58 ± 10 years. In 34 patients, stress single photon emission computed tomography (SPECT) myocardial perfusion imaging with thallium-201 or sestamibi was also performed. Hemodynamic measurements during the Mueller maneuver ( n = 10) showed a decrease in systemic pressure (139 ± 25 mm Hg vs 123 ± 24 mm Hg, p < 0.001) and pulmonary artery pressure (24 ± 6 mm Hg vs 14 ± 12 mm Hg, p = 0.01) and an increase in heart rate (67 ± 10 bpm vs 75 ± 14 beats/min, p = 0.001). Among the 34 patients who had perfusion imaging, the left ventricular ejection fraction remained unchanged or increased in 17 patients (group 1) (48% ± 19% vs 49% ± 21%, p not significant) and decreased (≥5%) in 17 patients (group 2) (55% ± 13% vs 40% ± 16%, p = 0.001). The stress SPECT images showed no or only fixed defects in 11 (65%) patients in group 1 and 3 (18%) patients in group 2 ( p = 0.02), and reversible defects in 6 (35%) patients in group 1 and 14 (82%) patients in group 2 ( p = 0.04). Group 2 had more regional dysfunction (measured as regional ejection fraction) than group 1 in the anterior wall and inferior walls ( p < 0.05, each). In 31 regions with regional dysfunction the SPECT images showed reversible defects in 18 (58%) segments and fixed defects in 8 (26%) segments. Thus the Mueller maneuver causes transient left ventricular dysfunction in many patients with coronary artery disease, especially those with stress-induced myocardial ischemia.

The value of radionuclide scrotal imaging in the diagnosis of acute testicular torsion

To assess the accuracy of radionuclide scrotal imaging (RSI) in the diagnosis of testicular torsion and torsion of testicular appendages. Eighty-seven patients (mean age 30.1 years, range 8-65) who presented with acute scrotal pain were evaluated by RSI and the results correlated with the clinical and surgical findings. Of the 87 patients, 44 underwent scrotal exploration and 42 patients were treated conservatively. One patient with a 'missed torsion' pattern on RSI refused operation and was lost to follow-up. Of the 44 patients who underwent surgery, testicular torsion was found in 30 and torsion of testicular appendages in 14 patients. The specificity of the RSI in diagnosing testicular torsion was 100% and the sensitivity was 98%. An area of increased tracer activity in the presence of a normal radionuclide angiogram was suggestive of torsion of testicular appendages with a specificity of 93%. Of the 42 patients who were treated conservatively, 19 had epididymitis, according to clinical and RSI findings, 10 had torsion of testicular appendages, two had orchiepididymitis, two had hydrocele, two had haematocele and seven patients had normal testes. At a follow-up examination, normal testicles were found in all 42 patients. The RSI may assist in the evaluation of nontraumatic acute scrotum, and can clearly distinguish among testicular torsion, torsion of testicular appendages and epididymitis.

Effects of Valve Surgery on Left Ventricular Contractile Function in Patients With Long-term Mitral Regurgitation

Patients with long-term mitral regurgitation were studied both before and 1 year after successful valve surgery to test the hypothesis that impaired left ventricular contractile function improves after surgery for long-term mitral regurgitation in humans. Fifteen patients with long-term mitral regurgitation were studied. Micromanometer left ventricular pressures and radionuclide angiograms for left ventricular volumes were acquired over a range of loading conditions both before and 1 year after successful valve surgery for long-term mitral regurgitation. To assess both left ventriculoarterial coupling to evaluate the interaction of the left ventricle with the arterial system with the use of the left ventricular contractile index, Ees, and effective arterial elastance, Ea. Left ventricular pump efficiency was expressed as the ratio of forward left ventricular stroke work to the corresponding pressure-volume area. All patients had successful mitral valve surgery as manifest by no or only trivial residual mitral regurgitation on physical examination and Doppler echocardiography. The average radionuclide regurgitant index of 1.28 +/- 0.56 was also less than the preoperative value of 2.70 +/- 0.80 (P < .0001). The mean left ventricular end-diastolic volume index decreased from 137 +/- 37 to 90 +/- 31 mL/m2 (P < .001), and the average left ventricular end-systolic volume index also decreased (59 +/- 29 to 45 +/- 27 mL/m2, P < .01), although individual variation was observed. The average left ventricular ejection fraction fell from 0.58 +/- 0.12 to 0.53 +/- 0.16, which was not significant. In contrast, Ees increased from a mean value of 0.95 +/- 0.66 mm Hg/mL during the preoperative study to 2.62 +/- 2.16 mm Hg/mL at the 1-year postsurgical study (P < .01). This improvement in left ventricular contractility was observed in patients with long-term mitral regurgitation, who before surgery had preserved left ventricular ejection fraction (P < .001), less left ventricular dilation at end diastole (P < .01) and end systole (P < .001), and less impaired left ventricular contractility. Because effective arterial elastance was unchanged, left ventriculoarterial coupling also improved from an average of 0.47 +/- 0.39 to 1.81 +/- 1.63 (P < .01). Consequently, left ventricular pump efficiency improved from a mean preoperative value of 0.23 +/- 0.10 to 0.55 +/- 0.22 at the 1-year postsurgical study (P < .0001). The results indicate that left ventricular contractile impairment is reversible in many patients with long-term mitral regurgitation. In fact, these data indicate that mitral valve surgery can be recommended to preserve left ventricular contractility in patients with long-term mitral regurgitation, particularly in those patients who before surgery have normal left ventricular ejection fractions and less left ventricular dilation and contractile impairment.

Incremental value of simultaneous assessment of myocardial function and perfusion with technetium-99m sestamibi for prediction of extent of coronary artery disease

This study assessed the incremental value of technetium-99m myocardial single-photon emission computed tomography (SPECT) and simultaneous first-pass radionuclide angiography, when added to treadmill exercise, for prediction of the extent of coronary artery disease. Technetium-99m count statistics permit the simultaneous assessment of myocardial perfusion and function. However, whether this characteristic improves prediction of the extent of coronary artery disease remains unknown. We studied 70 consecutive patients who had coronary angiography within 6 months of the scintigraphic study. All patients underwent a symptom-limited treadmill exercise test. Treadmill data were summarized using a previously validated score. Left ventricular ejection fraction and regional wall motion were evaluated from a first-pass radionuclide angiogram acquired at peak treadmill exercise in the anterior view. Perfusion was assessed visually. Extent of angiographic disease was expressed as the presence or absence of multivessel disease (more than two coronary artery territories with > 50% stenosis) and as a score that reflects the location of severe (> 75%) stenosis. Stepwise addition of scintigraphic data (perfusion first, followed by function) to the treadmill score showed significant incremental value for prediction of the angiographic score at each step; exercise ejection fraction alone was the strongest independent predictor. Discriminant accuracy for detection of multivessel disease was also improved by the addition of perfusion information to the treadmill score and addition of regional wall motion analysis to both of them. In this case, ejection fraction failed to show independent value. The addition of simultaneously performed sestamibi perfusion SPECT and first-pass radionuclide angiography to the treadmill exercise test significantly improved prediction of the extent of coronary artery disease.

Relationship Between Hemodynamics and Right Ventricular Function in Patients With Cardiomyopathy: Important Role of Tricuspid Regurgitation

Right ventricular (RV) ejection fraction is load sensitive, varying inversely with pulmonary artery pressure. We tested whether this relationship exists in dilated cardiomyopathy. Retrospective chart review. Tertiary care referral medical center. In 25 patients with cardiomyopathy referred for heart transplant evaluation (left ventricular ejection fraction 27 +/- 12%), hemodynamics, radionuclide angiograms, and Doppler echocardiograms were obtained initially (study A) and 8 +/- 8 months later (study B). Right ventricular ejection fraction was 40 +/- 17% on study A and 41 +/- 16% on study B, with a wide range of change between studies (+38 to -28%). Pulmonary artery systolic pressure (PASP) and right atrial pressure increased (52 +/- 9 to 61 +/- 10 mm Hg and 10 +/- 4 to 14 +/- 4 mm Hg, respectively, p < 0.05). There was no relation between PASP and RV ejection fraction (n = 50, r = -0.02, p = 0.87). Also, there was no relation between changes in PASP and RV ejection fraction (n = 25, r = 0.25, p = 0.15) between study A and B. However, there was a significant relation between interstudy changes in PASP and RV ejection fraction (n = 14, r = -0.71, p = 0.005) and end-systolic volume (n = 14, r = 0.53, p < 0.05) in patients in whom the degree of tricuspid regurgitation was either none or mild on both study A and B. In patients with cardiomyopathy, RV ejection fraction cannot be used as a noninvasive marker of pulmonary hypertension. Owing to variation in tricuspid regurgitation, alterations in pulmonary artery pressure over time may not lead to the expected change in RV ejection fraction or end-systolic volume.

Norepinephrine-induced left ventricular dysfunction in anesthetized and conscious, sedated dogs

These studies were conducted to evaluate effects of high dose norepinephrine infusion on left ventricular function in anesthetized and conscious dogs. Separate groups of pentobarbital anesthetized closed-chest dogs received norepinephrine infusion for 90 min followed by 1 h of recovery. Arterial pressure, electrocardiogram, two-dimensional echocardiogram and an equilibrium radionuclide angiogram were monitored. One hour following infusion of norepinephrine, left ventricular ejection fraction was reduced in a dose-dependent fashion. Fractional shortening was similarly reduced, with increased left ventricular systolic and diastolic dimensions also observed. Left ventricular end-systolic wall stress was increased at 60 min following infusion of norepinephrine but not saline: saline, 68 ± 8, norepinephrine, 4 μg/kg/min, 113 ± 8 g/cm 2. The left ventricular end-systolic wall stress/fractional shortening relationship showed reduction of contractility. In 10 conscious dogs pretreated with morphine, norepinephrine at 5 μg/kg/min × 90 min produced similar changes to those seen in anesthetized animals. Ejection fraction was reduced from 0.69 ± 0.3 to 0.36 ± 0.04 at 60 min post infusion. Fractional shortening was also reduced. Left ventricular end-diastolic dimension was increased. However, when animals were followed for 1 week, complete recovery occurred within 48 h. Histology showed mild contraction band necrosis in acute experiments and mild perivascular fibrosis in chronic experiments. Therefore, norepinephrine cardiotoxicity produced significant left ventricular dilation and reduction of ejection phase indices of left ventricular function associated with reduced contractility. In chronic dogs, histologic changes were mild, and left ventricular dysfunction was reversible.