lectrocardiographic (ECG) and echocardiographic examinations are 2 major tools for the identification of patients with hypertrophic cardiomyopathy (HCM). In almost all patients with HCM, echocardiography is more valuable not only for the diagnosis of the disease but also for the localization and the quantification of the hypertrophy when left ventricular hypertrophy (LVH) and ST-T abnormalities with or without abnormal Q waves are present on ECG. It is well known that asymmetric septal hypertrophy is the most common feature, 1 but many subgroups 2 or other forms of hypertrophy, such as apical, 3,4 symmetric, 5,6 or reversed posterior hypertrophy, 7 have been reported in the literature.In our daily practice, we occasionally encounter patients with ECG evidence of LVH that cannot be explained even with other invasive or noninvasive examinations. We recognized that in some of these patients, the papillary muscles of the left ventricle were hypertrophied on echocardiography, but no other hypertrophic segment could be detected. We also found this papillary muscle hypertrophy in the relatives of the patients with typical HCM in a family survey using echocardiography. Therefore, this present study was performed to examine whether solitary papillary muscle hypertrophy of the left ventricle is a new subtype of or an early form of HCM.
Japanese Circulation Journal Vol.62, November 1998
Methods
EchocardiographyTwo-dimensional echocardiographic observations were made via the transthoracic approach in the left lateral decubitus position with a 3.75 MHz transducer using a Toshiba SSH-140A or 160A apparatus (Toshiba Medical Co, Tokyo, Japan). When the visualization via the transthoracic approach was poor, echocardiographic evaluation was performed by the transesophageal approach with a 5 MHz transesophageal echocardiographic probe (Model PEF-507SB, Toshiba Medical Co) using the same apparatus.
Definition of Papillary Muscle HypertrophyAt present, there are no data concerning the size of the papillary muscle in normal subjects. Therefore, we determined the normal size of the papillary muscle by conducting an echocardiographic study in 40 healthy volunteers (23 males and 17 females, age range, 15-77 years) who showed normal physical and ECG findings. From the parasternal view of the transverse section of the left ventricle, where the bases of the papillary muscles were clearly visualized as circles and the muscles probably had their maximum sizes, the horizontal and vertical diameters of the anterolateral and posteromedial papillary muscles were measured at end-diastole. The horizontal diameter was measured in parallel with a line drawn between the centers of the anterolateral and posteromedial papillary muscles, and the vertical diameter perpendicularly to it (Fig 1). In the 3 patients whose left ventricles were poorly visualized on the parasternal approach, the measurements were made similarly but using the transgastric short-axis view via the Jpn Circ J 1998; 62: 811 -816 (Received May 6, 1998; revised manuscript received Ju...
