Frank G. Shellock

Evaluation of patients with persistent symptoms after lateral retinacular release by kinematic magnetic resonance imaging of the patellofemoral joint

The arthroscopic lateral retinacular release is typically performed to treat patellar pain and instability. This procedure was previously considered to be relatively benign with a low associated complication rate. However, a high incidence of medial subluxation of the patella was recently reported in patients with persistent symptoms after lateral retinacular release. Because the use of physical examination criteria may not always be sufficient to assess patellar alignment, 40 patients (43 knees) were evaluated by the newly developed technique of kinematic magnetic resonance imaging of the patellofemoral joint. One (2%) patellofemoral joint had normal patellar alignment, 10 (23%) had lateral subluxation of the patella, 1 (2%) had excessive lateral pressure syndrome, 27 (63%) had medial subluxation of the patella, and 4 (9%) had lateral-to-medial subluxation of the patella. Seventeen of 40 patients (43%) with unilateral arthroscopic lateral retinacular releases had medially subluxated patellae on the unoperated joints. Because patellar malalignment commonly affects bilateral joints, medial subluxation of the patella may have been present before the lateral retinacular release but was not recognized in these patients.

Myocardial metabolic and hemodynamic effects of intravenous MDL-17,043, a new cardiotonic drug, in patients with chronic severe heart failure

MDL-17,043, a new inotropic drug with vasodilator properties, has been shown to produce salutary hemodynamic effects in severe heart failure, but its effects on myocardial metabolism are unknown. To determine whether such hemodynamic effects are associated with adverse effects on the myocardial oxygen demand and supply relationship, we evaluated the effects of intravenous MDL-17,043 given in incremental doses to a mean maximum dose of 2.1 mg/kg, in nine patients with severe chronic heart failure. Overall cardiac pump performance was significantly improved by MDL-17,043, as reflected by an 88% increase in stroke work index (17 +/- 11 to 32 +/- 19 gm-m/m2; p less than 0.001), a 43% reduction in left ventricular filling pressure (28 +/- 4 to 16 +/- 5 mm Hg; p less than 0.0001), a 49% reduction in systemic vascular resistance (1832 +/- 490 to 937 +/- 296 dynes-sec-cm-5; p less than 0.0001) with a slight (11%) decrease in mean arterial pressure (86 +/- 17 to 76 +/- 19 mm Hg; p = 0.005) and without significant changes in heart rate (88 +/- 14 to 91 +/- 12 bpm; p = NS). These hemodynamic effects were associated with an 18% reduction in myocardial oxygen consumption (17 +/- 5 to 14 +/- 5 ml/min p = 0.01), a 17% reduction in myocardial arteriovenous oxygen difference (13.2 +/- 2.4 to 10.9 +/- 1.8 volumes %; p = 0.01), and a 120% improvement in external myocardial efficiency (stroke work index/oxygen consumption) (1.0 +/- 0.6 to 2.2 +/- 0.9; p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Radionuclide assessment of sequential changes in left and right ventricular function following first acute transmural myocardial infarction

The purpose of this study was to define the sequential changes in left and right ventricular ejection fraction (LVEF, RVEF) and regional LV wall motion following first transmural acute myocardial infarction (AMI). Fifty-four patients with either anterior (n = 28) or inferior (n = 26) infarction underwent radionuclide ventriculography (RNV) within 48 hours of onset of chest pain (study 1), between days 3 and 6 (study 2), and again between days 7 and 25 (study 3). Twenty-six of the patients with anterior MI (93%) had initial LVEF less than 0.54, compared with 13 of 26 patients (50%) with inferior MI (p less than 0.01). Eleven of 26 patients (42.3%) with inferior MI had initial RVEF less than 0.39, compared with 8 of 27 patients (29.6%) with anterior MI (p less than 0.01). There were no overall significant serial changes in mean LVEF or mean RVEF in patients with either anterior or inferior MI. From study 1 to study 2, LVEF did not change in 24 patients (44%), improved in 13 (24%), and worsened in 17 (31%). From study 1 to study 3, LVEF remained unchanged in 15 patients (35%), improved in 17 (39%), and worsened in 11 (26%). From study 1 to study 2, RVEF did not change in 25 of 51 patients (49%), improved in 17 (31%), and worsened in 9 (17%). From study 1 to study 3, RVEF remained unchanged in 14 (38%), improved in 18 (48%), and worsened in five (14%). Changes in EF tended to occur early in the hospital course, with little subsequent changes. Serial changes in EF could not be predicted by clinical or demographic variables or by location of infarction. Significant changes in LVEF typically occurred without concurrent change in regional LV wall motion, suggesting alteration in ventricular loading rather than change in intrinsic myocardial performance. Initial depression of LVEF correlated with in-hospital mortality as well as with development of congestive heart failure and conduction defects. However, sequential changes in LVEF did not correlate with short-term prognosis. We conclude that sequential changes in LVEF and RVEF occur frequently following AMI, appear to reflect ventricular loading conditions rather than intrinsic change in myocardial performance, and do not correlate well with short-term prognosis.

Comparative hemodynamic effects of intravenous dobutamine and MDL-17,043, a new cardioactive drug, in severe congestive heart failure☆

In 14 patients with severe congestive heart failure (CHF) due to ischemic heart disease or idiopathic dilated cardiomyopathy, the hemodynamic response to intravenous infusion of dobutamine (D) was compared to that of a new non-catechol, non-glycoside, inotropic and vasodilator agent, MDL-17,043 (MDL) administered in incremental intravenous doses. D and MDL produced comparable increases in cardiac index (L/min/m2) (1.8 +/- 0.4 to 2.9 +/- 0.8 and 1.7 +/- 0.3 to 3.3 +/- 0.6, respectively; both p = 0.001) and stroke volume index (ml/beat/m2) (24 +/- 8 to 35 +/- 9 and 22 +/- 7 to 39 +/- 11, respectively; both p = 0.001). Both D and MDL reduced left ventricular filling pressure (29 +/- 5 to 24 +/- 5 and 29 +/- 6 to 17 +2- 6 mm Hg, respectively; both p less than 0.05), and mean right atrial pressure (11 +/- 4 to 8 +/- 4 and 13 +/- 5 to 6 +/- 4 mm Hg, respectively; both p = 0.001). The overall changes in heart rate and mean arterial pressure were small with both D and MDL. However, MDL in comparison to D resulted in a significantly lower left ventricular filling pressure (p = 0.001), mean pulmonary arterial pressure (p = 0.001), and mean arterial pressure (p less than 0.05). The salutary hemodynamic effects of MDL on cardiac index and left ventricular filling pressure were sustained for an average of 9.6 hours, whereas the effects of D dissipated within 30 minutes of stopping the infusion. No serious adverse effects were noted during acute administration with either drug. Therefore, intravenous MDL may be a useful substitute for D in the acute therapy of severe CHF.

Comparative acute hemodynamic effects of intravenous sodium nitroprusside and MDL-17,043, a new inotropic drug with vasodilator effects, in refractory congestive heart failure

We compared the acute hemodynamic effects of intravenous nitroprusside (NTP), a pure vasodilator, to those of intravenous MDL-17,043 (MDL), a phosphodiesterase inhibitor with inotropic and vasodilator effects, in 12 patients with chronic refractory congestive heart failure (CHF). Intravenous NTP was infused and titrated to achieve optimal hemodynamic effects, whereas MDL was given intravenously in 0.5 mg/kg increments every 10 to 15 minutes until no further increase occurred in cardiac output or until a maximum cumulative dose of 4.5 mg/kg had been given. Both NTP and MDL reduced pulmonary capillary wedge pressure (27 +/- 5 to 15 +/- 6 and 29 +/- 3 to 15 +/- 7 mm Hg, respectively; both p less than 0.0001), systemic vascular resistance (2173 +/- 1137 to 1118 +/- 306 and 1805 +/- 425 to 956 +/- 235 dynes-sec-cm-5, respectively; both p less than 0.0002), mean arterial pressure (85 +/- 18 to 69 +/- 14 and 83 +/- 15 to 75 +/- 16 mm Hg respectively; both p less than 0.05), and increased cardiac index (1.7 +/- 0.4 to 2.6 +/- 0.4 and 1.8 +/- 0.2 to 3.3 +/- 0.5 L/minute/m2, respectively; both p less than 0.05) without an overall significant change in heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained benefits of oral pentaerythritol tetranitrate on ventricular function in chronic congestive heart failure

The hemodynamic effects of a single oral dose of 80 mg pentaerythritol tetranitrate (PETN) were determined over a 5‐hr period in 16 patients with chronic congestive heart failure. PETN decreased (p < 0.05) pulmonary capillary wedge pressure (27 to 18 mm Hg), right atrial pressure (15 to 9 mm Hg), mean systemic arterial pressure (89 to 80 mm Hg), and systemic vascular resistance (1,812 to 1,466 dynes · sec · cm−5). There were increases (p < 0.01) in cardiac index (2.0 to 2.31/m2/min), stroke volume index (24 to 28 ml/m2), and stroke work index (25 to 31 gm‐m/m2). Peak reduction in pulmonary capillary wedge pressure occurred 2 hr after PETN and hemodynamic effects were still apparent at 5 hr. In nine patients in whom left and right ventricular ejection fractions were determined by radionuclide ventriculography before and after PETN, no changes were found in left ventricular ejection fraction (0.20 to 0.22, p = NS) although there was a modest increase in right ventricular ejection fraction (0.29 to 0.34, p < 0.05). The data indicate that oral PETN may induce beneficial effects on preload and afterload in congestive cardiac failure that may last 5 or more hours.

Magnetic resonance imaging-guided interstitial application of laser aided by fiber optic temperature sensing

In order to further understand signal variations observed on magnetic resonance imaging scans of interstitial laser heating, a commercial multichannel fluoroptic thermometer, equipped with fiber optic sensors, was employed in conjunction with the laser/MRI phototherapy system. Three calibrated fiber optic sensors of the thermometer were used to measure temperature changes in ex-vivo sheeps brain at various distances directly across from the beam of a Nd:YAG laser emitted from a bare fiber. Laser was operated at 5 W for 220 sec. Temperature was measured every 10 seconds and MR images were acquired during and after laser irradiation until temperature in all probes returned to the equilibrium level of prelaser irradiation. Image contrast analysis of the heated region showed that MRI signal variations, during heating and cooling periods, correlated well with the changes in temperature. It is concluded that direct thermometry of MRI-monitored laser application will aid in understanding the effects of high focal heating on the MRI signal.

Chronic effects in temperature-controlled application of MRI-monitored interstitial laser therapy

The goal of interstitial laser therapy is to destroy neoplastic tissue through localized heating. Temperature elevations to the necrotic coagulation threshold of about 60 degree(s)C cause the induction of irreversible, as well as, reversible alterations to tissues. While chronic effects prevail days following the treatment, the relevant issue from the perspective of magnetic resonance imaging-monitoring of laser therapy, is the ability of MRI in detecting these effects. In this study time-course MRI images of rabbit musculature, treated with temperature controlled Nd:YAG laser irradiation were correlated with histological changes. The MRI appearance of the interstitial laser lesion can be divided into three categories of acute, sub- acute, and chronic. The dynamics of chronic lesion development, including variations in shape, size and composition of the lesion were successfully documented by T2-weighted spin echo MRI.