Twenty (16 females and 4 males) patients with rare cardiac arrhythmias were investigated with simultaneously recorded ECG and M-mode echocardiographic tracings. In some of the patients a pulsed Doppler echocardiographic registration was also performed in subcostal view to detect the reverse flow towards the inferior vena cava. Our study proves, that the registration of the motion of cardiac structures including mitral valves in parasternal long axis view, the tricuspid a-v groove in subcostal view, and the registration of reverse flow's mass towards the inferior vena cava from subcostal view simultaneously with ECG tracing is very useful for the analysis of cardiac arrhythmias.

Key words: Echocardiography - Atrioventricular block - Premature beat - Atrial fibrillation and flutter - Atrial standstill.

GELLÉRI D. Význam echokardiografie pri vyšetrovaní porúch srdcového rytmu. Noninvas Cardiol 1996;5(2):

Dvadsa? pacientov (16 ?ien a 4 mu?i) so zriedkavými poruchami srdcového rytmu bolo vyšetrených pomocou simultánneho pou?itia EKG záznamu a M-mode echokardiografie. U niektorých pacientov sa vykonalo vyšetrenie s pou?itím pulzného Dopplera v subkostálnom poh3ade so zameraním na detekciu reverzného prietoku smerom k dolnej dutej ?ile. Naše výsledky dokázali, ?e simultánna registrácia EKG záznamu a pohybu mitrálnej chlopne v parasternálnej dlhej osi, trikuspidálnehej atrio-ventrikulárnej ryhy zo subkostálneho poh3adu a registrácia spätného prietoku do dolnej dutej ?ily zo subkostálneho poh3adu sú pre analýzu porúch srdcového rytmu ve3mi u?itoené.

K3úeové slová: Echokardiografia - Atrioventrikulárna blokáda - Extrasystoly - Fibrilácia a flutter predsiení - Zastavenie predsiení

From Cardiovascular Care Station of county Jász-Nagykun-Szolnok, Szolnok, Hungary

Manuscript received April 28, 1995; accepted December 12, 1995

Address for correspondence: Dezso Gelléri, M.D. Ph.D., Cardiovascular Care Station of County Jász-Nagykun-Szolnok, Szolnok, Hosök tere 2-4, 5000-Hungary.

Before the advent of the echocardiographic method Benchimol demonstrated the developing of giant "a" waves in jugular venous pulse tracing during third degree a-v block showing that this situation was unfavourable from a hemodynamical point of view (1).

The above mentioned facts persuaded us to publish our observations in association with echocardiographic investigation of arrhythmias. Until now investigations have not played an important role in cardiological literature.

Group of patients and methods

Since 1985 we have been using echocardiography in the investigation of patients with cardiac arrhythmias. The most interesting cases have been collected in this study. The data of twenty patients (16 females and 4 males) was studied. Their distribution according to age, sex, diagnosis and others can be seen in table 1.

Table 1 Distribution of the patients with regard to age, sex, diagnosis and others
f.= female, m.= male, d. = disease, M.= mitral valve, A.= aortic valve, TR. = tricuspid a-v groove, IVC. = inferior vena cava, +++ = unfavourable, ++ = less unfavourable, + = not unfavourable, - = favourable, detto = see above.

Each patient underwent a full echocardiographic examination which observed and recorded the movement of the following cardiac structures: aortic root, aortic valves, left atrium and the mitral valves in parasternal long-axis view as well as tricuspid a-v groove in subcostal view. In some cases pulsed Doppler echocardiography was also carried out. For the echocardiographic investigations a Philips SDU-3000 and an ATL Ultramark-7 were used.

Results

The clinical problems and dates are demonstrated in the table. Occasionally the absence of the mitral valves' opening in the presystolic phase during sinus tachycardia was observed (case 1). This is so in a case where a prolonged PR interval is present simultaneously (case 3), which is unfavourable from a hemodynamic viewpoint.

In a first degree a-v block with extremely long PR interval, the P wave may be hidden in the end of the T wave of the previous cardiac cycle, causing possible difficulty in ECG diagnosis (case 6, Fig. 2, left side). In this case, the movement of the tricuspid a-v groove (Fig. 1) shows well the hidden P waves. Later a Wenckebach periodicity with an inverse behaviour of the first heart sound's intensity developed in this case. (Fig. 3) Interestingly, when the PR interval is extremely long, the mitral valve may reopen during the presystolic phase without any atrial contraction, a very favourable situation for mitral inflow. In this case, a very accentuated first heart sound may be heard (case 6). So far two similar cases have been observed. In another patient with second degree a-v block, the blocked atrial contraction coincided with rapid left ventricular inflow resulting in the impact of the anterior mitral leaflet into the septum, causing a little movement. The prescribed treatment for this patient was prophylactic antibiotics preceding surgical intervention to avoid bacterial endocarditis (case 7).

Fig. 1 Left side. Two-dimensional echocardiography for studying the movement of the tricuspidal a-v groove. Right side. M-mode presentation of the left side picture. The contraction of the atria results in the downward movement of the a-v groove. The movement of the tricuspid a-v groove draws the inferior angles of the triangles in a downward direction. The end or the peak of P wave coincides approximately with the left basic point of the triangle (arrow 1). Arrow 2 shows a hidden P wave in the T wave of the interpolated beat. Abbreviations: L = liver; RV = right ventricle; RA = right atrium; TR = tricuspid a-v groove; ECG II. = ECG lead II.

Fig. 2 Left side (see Tab. 1, case 6). One can not see any P waves on the ECG, which is suspected of having junctional rhythm. The triangles show that the movement of the tricuspid a-v groove begin with the end of T waves indicating that the P waves are hidden in the T waves of previous cardiac cycles (arrow). So the diagnosis is sinus tachycardia with extremely long PR intervals. After the decrease of the heart frequency, the P waves became visible and a second degree a-v block developed (see Fig. 3). Right side (see Tab. 1, case 12.) No P waves are visible on the ECG, but the movement of the tricuspid a-v groove shows a normal mechanical atrial activity preceded by the R wave. The 12 leads of the ECG were reviewed and P waves could be observed in lead V2. So the correct diagnosis was atrial low voltage with normal atrial mechanical activity. Abbreviations: See Fig. 1.

Fig. 3 Second degree a-v block with Wenckebach periodicity (see Tab. 1, case 6). There are some interesting phenomena in this case. First: The longer the PR interval, the more accentuated was the first heart sound. Generally, this happens in reverse namely the longer the PR interval, the less accentuated is the first heart sound. Second: During observation of the anterior mitral leaflet's motion, one could observe that the "A" wave followed by P wave coincided with the "E" point, followed by the mitral leaflet reopening in the presystolic phase ("Á"). This opening increases in size from systole to systole (marked e) so its closing occurs with a higher and higher amplitude, gradually resulting in an increase of the first heart sound's intensity. Third: At the shortest (0,36 sec) PR interval the mitral valve did not reopen in the presystolic phase, so the first heart sound was the softest in this cardiac cycle. Probably, at the shortest PR interval the time is too short for the mitral valve to reopen, while at PR intervals longer than 0,36 sec, there is much more time for the reopening of the mitral valve with help of a "rebound" phenomenon. Abbrevations: A, C, D = the end points of mitral valve echogram. 1, 2, 4 = the number of heart sounds, PCG (35 Hz) = phonocardiogram 35 Hz, M = mitral valve, see Fig. 1.

From a hemodynamic point of view a supraventricular premature beat (case 9, 11) is more favourable than a ventricular one (case 14) because it is preceded by an atrial contraction insuring a good left ventricular filling and a good stroke volume. The exception to this scenario is in the case of diseased aortic leaflets, which prevent the wide separation of the valves (case 10). A ventricular premature beat does not interfere with ventricular filling considerably if it is far from the T wave of the previous cardiac cycle, especially if this is an interpolated beat (case 15, Fig. 4).

Fig. 4 Left side. Interpolated ventricular premature beats (see Tab. 1, case 15.). The motion of the tricuspid a-v groove clearly shows that P waves belonging to the next normal cardiac cycle can be found in the T waves of ventricular premature beats. Right side: This is the anterior mitral valve's motion of the same patient during normal and premature beats. It can be clearly observed that the rhythm of the motion of the mitral valve has not been affected by the ventricular premature beat. The interpretation of this phenomenon is as follows: the extrabeat caused a premature closure of the mitral valve, whose timing was similar to the natural approaching of mitral valves occuring in normal diastole. After the interpolated beat the new opening of the mitral valve was caused by the rapid filling of the left ventricle, while in the nonextrasystolic beat the new opening of the mitral valve was caused by the left atrium's contraction. It is clear that the moving' shape of the mitral valve in extrasystolic and nonextrasystolic beats are similar, but the hemodynamic process is quite different. Abbreviations: see Fig. 1 and Fig. 3.

There may be a considerable difference between the mechanical and the electrical activity of the atria in cases with atrial fibrillation and flutter. In case 13 the ECG showed atrial fibrillation and flutter while the motion of the mitral valves contained many small "a" waves which were proved to be pure atrial flutter. In this case one could observe a downstepped left ventricular inflow with pulsed Doppler echocardiography. It is of interest that the mitral valves of a patient with atrial fibrillation could reopen in presystolic phase as well as those of the three previously mentioned patients with extremely long PR intervals proving that the opening of mitral valves does not necessarily require atrial contraction.

It is possible to make a differential diagnosis between serious low voltage of the atria and atrial standstill (7) with the observation of the tricuspid a-v groove's motion in subcostal view (case 12, Fig. 2 right side). So far two similar cases have been observed.

The reverse flow towards the inferior vena cava detected by pulsed Doppler echocardiography in subcostal view may be used for the localisation of hidden P wave as well as for the estimation of the reverse flow's mass. Reverse flow with fixed coupled times to the QRS complexes' beginning prove a-v association existing for example in supraventricular tachycardia with 2:1 block (case 16,17) in supraventricular tachycardia with prolonged a-v interval (case 19, Fig. 5 left side) or in retrograde conduction, while reverse flow without fixed coupled times to the QRS complexes prove a-v dissociation existing in ventricular tachycardia (case 18, Fig. 5 right side).

Fig. 5 Left side (see Tab. 1 case 19.) The P waves coincide with the ST segments of the previous cardiac cycles, so they are hidden, but the little reverse flow towards the inferior vena cava (r) show the existence of the P waves. Every second beat has a wide QRS complex. Diagnosis: Supraventricular paroxysmal tachycardia with a long PR interval and with intermittant aberration (a-v association). Right side (see Tab. 1 case 18.). During the run containing 3 beats the two reverse flows' distance (rr) is equal to the PP interval on ECG, but the reverse flows' coupled times to the beginning of QRS complexes vary from 0,26-0,34 sec. Diagnosis: Non sustained ventricular tachycardia (a-v dissociation). Abbreviations: a = anterograde flow, r = reverse flow, ECG III. = ECG lead III. See: Fig. 1.

Discussion

The first attempt to use echocardiography in the investigation of arrhythmias was in the observation of the mitral valves' motion and the first heart sound in third degree a-v block. Shah et al. (8) showed, that the closing amplitude and the closing speed of the mitral valve were closely related to the intensity of the first heart sound. The higher the closing amplitude and the closing speed of the mitral valve (the amplitude of "A" wave and the AC slope) the louder is the first heart sound and vice versa. Our observations were similar in second degree a-v block with extremely long PR intervals adding that it is possible for the mitral valve to reopen in presystolic phase without atrial contraction (this opening might be caused by the rebound phenomenon). The presystolic opening of the mitral valve may be favoured from a hemodynamic point of view insuring a good presystolic inflow which rises to 33 % of the whole diastolic inflow. An exception is the case in which the PR interval is so long that the atrial contraction occurs during late systole of the previous cardiac cycle resulting in a considerable reverse flow towards the inferior vena cava.

Subcostal M-mode echocardiography of the right atrial wall for use as a tool in the analysis of arrhythmias was published by Drinkovic (2). We have used subcostal 2-D echocardiography in investigating cardiac structure and believe it to be the best in this field. We have found that the motion of the tricuspid a-v groove is the best for this purpose. The reasons are as follows: 1. It is very easy to cut and get a good quality of M-mode tracing from the subcostal view. 2. The motion of the tricuspid a-v goove is preserved even in cases in which the left side motion of the groove is limited; caused by impaired left ventricular function (9). 3. Each cardiac arrhythmia shows a specific groove’s motion pattern.

The observation of the tricuspid a-v groove's motion is a reliable tool in the localisation of hidden P waves in the ECG as well as for estimating of the force of the atrials' contraction. This is because there is a considerable difference between the electrical and the mechanical activation of the atria during arrhythmias (2).

It has been known for many years that the electrical restoration of sinus rhythm in patients with atrial fibrillation and flutter, does not mean the immediate restoration of the mechanical activity of the atria. This phenomenon needs hours, days or weeks (10). Observation of the groove's motion gives us a simple method of detecting the revival of atrial contraction after electrical cardioversion or pacing.

The pulsed Doppler echocardiography in subcostal view has probably not yet been used to detect the exact localization of hidden P waves of ECG with help of reverse flow.

Conclusions

1. The most important information in patients with cardiac arrhythmias could be deduced from observation of the motion of the mitral valves and tricuspid a-v groove.

2. During an extremely long PR (PQ) interval the mitral valves can reopen without atrial contraction in the presystolic phase of the cardiac cycle, which has a favourable hemodynamic effect.

3. During atrial fibrillation, or during simultaneous fibrillation and flutter the electrical and mechanical activity of the atria may show a considerable difference.

4. Echocardiography may help us to distinguish between low voltage of the P wave and atrial standstill.

5. The reverse flow towards the inferior vena cava detected by pulsed Doppler echocardiography in subcostal view may be used for the localization of hidden P waves as well as for that of the estimation of the reverse flow's mass in patients with a-v association and dissociation.

Reference

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