Norio Kamiyama

Noninvasive detection of total occlusion of the left anterior descending coronary artery with transthoracic doppler echocardiography

OBJECTIVES The purpose of this study was to evaluate the value of transthoracic Doppler echocardiography (TTDE) for the noninvasive detection of total left anterior descending coronary artery (LAD) occlusion. BACKGROUND Total coronary occlusion is associated with an adverse long-term prognosis, and mechanical revascularization may be required for the patient with total coronary occlusion. However, a noninvasive diagnosis of total coronary occlusion before coronary angiography (CAG) has been difficult, especially in patients without clinical signs. METHODS We studied 103 consecutive patients who underwent CAG for the evaluation of coronary artery disease. The study group consisted of 16 patients with total LAD occlusion (group A) and 87 patients without total LAD occlusion (group B). Coronary flow velocity in the mid-portion of the LAD was recorded by TTDE. RESULTS Adequate spectral Doppler recordings of diastolic flow in the LAD were obtained in 98 study patients (95%; 15 patients in group A and 83 patients in group B). In group A, retrograde LAD flow was obtained in 14 (93%) of 15 patients. The mean diastolic velocity of the retrograde flow was 21.0 +/- 6.1 cm/s. In group B, antegrade LAD flow was obtained in all 83 patients (100%). The mean diastolic velocity of the antegrade flow was 21.5 +/- 7.1 cm/s. Retrograde LAD flow by TTDE had a sensitivity of 93% and a specificity of 100% for the detection of total LAD occlusion. CONCLUSIONS Retrograde flow in the LAD by TTDE is a highly sensitive and specific finding that can be used to noninvasively diagnose total LAD occlusion.

Assessment of coronary flow reserve by coronary pressure measurement ; comparison with flow- or velocity-derived coronary flow reserve

OBJECTIVES This study sought to assess the reliability of pressure-derived coronary flow reserve (CFR) compared with flow- or velocity-derived CFR. BACKGROUND Coronary flow reserve has been reported to have important clinical implications for the evaluation and treatment of coronary artery disease. METHODS Using a pressure guide wire, coronary pressure distal to the stenosis was measured at rest and during hyperemia in seven dogs with various degrees of stenosis and in 30 patients with angina (29 and 34 stenoses in total, respectively). Pressure at the tip of the guiding catheter was also recorded with a fluid-filled transducer system. Pressure-derived CFR was calculated by the square root of the pressure gradient across the stenosis (DeltaP) during hyperemia divided by DeltaP at rest, using a proprietary software system. At the same time, coronary flow was monitored proximal to the stenosis with a flow meter in the experimental dogs, and coronary flow velocity distal to the stenosis was assessed using a Doppler guide wire in patients with angina. Flow-derived (or velocity-derived) CFR was compared with pressure-derived CFR. RESULTS Except for one stenosis that showed no DeltaP at rest, a significant correlation was obtained between pressure- and flow-derived CFR in the animal study (y = 1.05x - 0.03, r = 0.92, p = 0.0001). A significant correlation was also seen between pressure- and velocity-derived CFR in the human study, except in three stenoses with no resting DeltaP (y = 0.70x + 0.37, r = 0.85, p = 0.0001). CONCLUSIONS Similar to flow (or velocity) measurement, CFR can be assessed by pressure measurement, except in stenoses with minor resting DeltaP.

Electrocardiographic features differentiating dilated cardiomyopathy from hypertrophic cardiomyopathy

To determine the usefulness of electrocardiographic (ECG) features in differentiating between hypertrophic cardiomyopathy with features mimicking dilated cardiomyopathy (D-HCM) and true dilated cardiomyopathy (DCM), we compared ECGs of 52 consecutive patients (11 with D-HCM, 41 with DCM). Left atrial dimension, left ventricular internal dimension, and septal and posterior wall thickness were employed as echocardiographic indexes, while QRS duration, amplitude of RV5 or V6 + SV1, number of abnormal Q waves, P-terminal force in V1, and frontal plane QRS axis were used as ECG parameters. The patients with D-HCM demonstrated a larger number of abnormal Q waves (P < .0001), greater prolongation of QRS duration (P < .0001), and lower amplitude of RV5 or V6 + SV1 (P < .0001). In all cases of D-HCM, atrial overload was observed and abnormal QRS axis in 9 (82%) of the 11 patients. These features were noted in 21 (51%) and 17 (41%), respectively, of the 41 DCM patients (P < .005 and P < .05, respectively). Despite significant differences in the echocardiographic parameters between D-HCM and DCM, excluding left ventricular end-diastolic dimension, ECG abnormalities were more significant between the two groups. The results indicate that ECG features are extremely useful in differentiation between DCM and D-HCM.