Intraventricular blood flow during isovolumetric relaxation and diastole in hypertrophic cardiomyopathy
C Seiler1, R Jenni, H P Krayenbuehl
1Medical Policlinic, University Hospital, Zurich, Switzerland.
Insights
Doppler echocardiography revealed abnormal intraventricular blood flow in hypertrophic cardiomyopathy patients. These patterns, including retrograde isovolumetric relaxation flow and diastolic antegrade flow, are linked to myocardial relaxation abnormalities.
Area of Science:
- Cardiology
- Medical Imaging
- Physiology
Background:
- Hypertrophic cardiomyopathy (HCM) is a complex cardiac condition characterized by myocardial thickening.
- Intraventricular blood flow dynamics in HCM are not fully understood, particularly during different phases of the cardiac cycle.
- Previous studies have not comprehensively investigated the spectrum of abnormal blood flow patterns in HCM using advanced imaging techniques.
Purpose of the Study:
- To investigate intraventricular blood flow abnormalities in patients with hypertrophic cardiomyopathy using Doppler echocardiography.
- To characterize different types of abnormal blood flow movements during systole, isovolumetric relaxation, and diastole in HCM.
- To explore the relationship between specific blood flow patterns and the type and severity of left ventricular hypertrophy.
Main Methods:
- Doppler echocardiography was performed on 40 patients diagnosed with hypertrophic cardiomyopathy.
- Patients were selected based on the presence of at least one of four defined abnormal left ventricular blood flow patterns.
- Blood flow velocities and patterns were analyzed during systole, isovolumetric relaxation, and diastole.
Main Results:
- Abnormal systolic outflow/midventricular obstruction occurred in 20/40 and 6/40 patients, respectively.
- Retrograde isovolumetric relaxation flow (IVRFretro) was observed in 28/40 patients, with a mean velocity of 0.7 m/s.
- Diastolic antegrade flow (DFante) was present in 10/40 patients, more frequently in apical HCM (9/11) than asymmetric septal hypertrophy (1/29).
- Higher velocities for IVRFretro and DFante were noted in patients with marked asymmetric hypertrophy.
- IVRFretro and DFante were more prevalent in apical HCM, potentially due to apical cavity obliteration.
Conclusions:
- Hypertrophic cardiomyopathy is associated with diverse intraventricular blood flow abnormalities during isovolumetric relaxation and diastole.
- These flow abnormalities are likely caused by asynchronous relaxation of hypertrophied myocardium.
- Diastolic antegrade flow is a significant finding, particularly in apical HCM, suggesting localized ventricular remodeling impacts flow dynamics.
Abstract:
Forty patients with hypertrophic cardiomyopathy were investigated by Doppler echocardiography for intraventricular blood flow abnormalities. None had a bundle branch block. The patients were recruited on the basis of the presence of at least one of four different types of abnormal left ventricular blood flow movements during systole, isovolumetric relaxation, and diastole (time after mitral valve opening). The abnormal blood flow patterns were composed of the following: (1) systolic left ventricular outflow and midventricular obstruction in 20 of 40 and in 6 of 40 patients, respectively; (2) retrograde isovolumetric relaxation flow (IVRFretro; mean velocity, 0.7 +/- 0.3 m/sec), that is, flow toward the apex of the left ventricle, in 28 of 40 patients; (3) antegrade isovolumetric relaxation flow (IVRFante; mean velocity, 1.6 +/- 1.0 m/sec), that is, flow toward the left ventricular outflow tract, in 3 of 40 patients; and (4) diastolic antegrade flow (DFante; mean velocity, 0.9 +/- 0.3 m/sec), that is, flow opposite to mitral inflow, in 10 of 40 patients. There were significantly fewer patients with asymmetric septal hypertrophy (group 1) than with apical hypertrophic cardiomyopathy (group 2) showing DFante (1/29 versus 9/11, p less than 0.01). IVRFretro and DFante revealed higher velocities in patients with marked left ventricular asymmetric hypertrophy than in those with mild hypertrophy. Thus, in hypertrophic cardiomyopathy and especially in patients with marked asymmetric hypertrophy, there are different types of abnormal intraventricular blood flow movements during isovolumetric relaxation and disatole. This phenomenon is probably caused by asynchronous relaxation of the asymmetrically distributed, hypertrophied myocardium. DFante is more often observed in the apical cardiomyopathy than other forms of hypertrophic cardiomyopathy probably attributable to apically localized left ventricular cavity obliteration.
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