Volume loading in predominant right ventricular infarction: bedside haemodynamics using rapid response thermistors.

Intravenous fluid loading is commonly used for the treatment of low cardiac output (CO) syndrome complicating severe right ventricular infarction (RVMI). We prospectively evaluated the effectiveness of this method in 11 consecutive patients (age 66 +/- 14 years) with severe RVMI, using a newer thermodilution method with rapid response thermistors. Volume loading was performed until pulmonary wedge pressure (PWP) reached 18 to 24 mmHg. Right atrial pressure (RAP), pressures of the right ventricle (RV) and pulmonary artery (PA), PWP, RV volumes, RV ejection fraction (RVEF), stroke volume (SV), CO, pulmonary vascular resistance (PVR) and RAP/PWP ratio were measured before and after volume loading. RAP rose from 12 +/- 4 to 19 +/- 5 mmHg (P < 0.0001) and its tracing showed a non-compliant pattern in all patients. RV end-diastolic pressure rose from 13 +/- 4 to 20 +/- 5 mmHg (P < 0.0001) and PWP from 14 +/- 3 to 20 +/- 6 mmHg (P < 0.0001). Mean PA pressure rose from 20 +/- 3 to reach 25 +/- 6 mmHg (P < 0.001), while PVR did not change significantly (117 +/- 39 vs 101 +/- 49 dyn.s.cm-5, P ns). RAP/PWP ratio rose from 0.85 +/- 0.14 to 1.05 +/- 0.07 (P < 0.01). The end-diastolic RV volume increased from 95 +/- 26 to 113 +/- 24 ml.m-2 (P < 0.001); however, RV end-systolic volume increased from 65 +/- 28 to 83 +/- 29 ml.m-2 (P < 0.01), thus SV did not change significantly (30 +/- 6 vs 30 +/- 8 ml.beat-1.m-2, P ns). RVEF decreased from 32 +/- 11 to 28 +/- 11% (P < 0.001). CO did not improve significantly (2.3 +/- 0.42 vs 2.4 +/- 0.62 l.min-1.m-2, P ns) neither did the clinical status.(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting coronary artery disease with treadmill stress testing: changes in R-wave amplitude compared with ST segment depression.

Coronary angiograms and treadmill stress tests were reviewed independently in 108 nonconsecutively selected cases. There were 16 patients (15%) with infarcts on ECG. Changes in R-wave amplitude and ST segments during exercise were evaluated to determine the sensitivity and specificity of each as a predictor of coronary artery disease (CAD). ST segment changes had a sensitivity of 49%, and a specificity of 74%. The sensitivity increased to 55% when infarcts were excluded. R-wave amplitude changes had a sensitivity of 68% and a specificity of 84%. The sensitivity increased to 78% when infarcts were excluded. An index formed by the sum of the change in R-wave amplitude and the magnitude of ST segment change yielded a sensitivity of 76% and specificity of 78%. The sensitivity increased to 84% when infarcts were excluded. There was no statistical difference between specificities for each criteria. Of those patients with an R-wave amplitude decrease, 69% had no coronary artery atherosclerosis, while 31% had significant lesions. Of those patients with no change or an increase in R-wave amplitude, 83% had coronary artery atherosclerosis, while 17% were normal. Of the 83% with coronary artery atherosclerosis, 81% had two and three vessel disease, while only 19% had single vessel disease. No change or an increase in R-wave amplitude during treadmill stress testing is a more reliable indicator of CAD in our laboratory than ST segment changes.

Evaluation of R wave amplitude changes versus ST-segment depression in stress testing.

Exercise ECGs and coronary angiograms were reviewed in 266 patients (81 normals and 185 with significant coronary artery disease). Thirty-three false positive and 96 false negative ST responses to stress testing were purposely chosen to determine if the R wave could reduce the number of false ST responses. R wave amplitude changes were measured in the control and in the immediate postexercise period. An increase or no change in R wave was taken as evidence of an abnormal response, while a decrease in the R wave was a normal response. The sensitivity by ST segment was 48% and the specificity was 59%. These values were low because of the large number of false positive and negative ST responses in the study. It was our purpose to determine if these lowered values could be significantly improved by the R wave. Using R wave criteria, the sensitivity was 63% (P is less than 0.01) while the specificity was 79% (P is less than 0.01). The sensitivity and specificity of stress testing can be significantly improved using R wave changes.

Significance of changes in R wave amplitude during treadmill stress testing: angiographic correlation.

Coronary angiograms and treadmill stress tests were reviewed in 89 patients. Changes in R wave amplitude were measured in the control and immediate postexercise periods. Of 45 patients with normal coronary arteries, 41 (91 percent) had a decrease in R wave amplitude (P less than 0.01); 3 (7 percent) had an increase in amplitude, including 2 with abnormal left ventriculograms. The remaining patient (2 percent) had abnormal wall motion but no change in R wave amplitude. Among the 44 patients with significant coronary artery disease (70 percent or greater luminal narrowing in one or more vessels), R wave amplitude increased after exercise in 26 (59 percent) with more severe coronary artery disease. R wave amplitude decreased in 18 patients (41 percent) with normal or minimally abnormal resting ventriculograms and less severe coronary artery disease (P less than 0.01). Changes in R wave amplitude reflect ventricular function, an increase in R wave amplitude reflecting more severe dysfunction and severe coronary narrowing. A decreased R wave amplitude indicates normal or minimal dysfunction and is strongly associated with normal coronary angiograms.