‘TAP, TAP, TAP,’ demanded the conductor’s baton. Activity ceased as all eyes focused on the determined looking fellow behind the music stand. Poised and ready, the orchestra fairly steamed with excitement in anticipation of their cue. Slowly, but precisely, the conductor turned towards the audience and announced, “For our first movement, we present… Sinus Rhythm.” With that, he made a dignified turn back towards his musicians, reveling in the sense of awe his announcement had awarded him. Indeed, he was the conductor, the pacemaker, the SA node, and with a flick of the wrist, he proceeded to direct the ‘Symphony of Life.’
Softly and rhythmically the music began. Steadily it continued as the Cardiac Orchestra followed along with his every command. ‘lub-DUB, lub-DUB, lub-DUB’ went the melodious notes in perfect synchronization. Oh, how he loved conducting such a superb ensemble of musicians with each cell-mate performing the vital role perfectly. He made a mental note to congratulate the mitral and tricuspid sections on closing perfectly to make their soft, low-pitched lub. Indeed, the pulmonic and aortic valve sections deserved recognition as well for their strong and distinct DUB. Directing such a concert was no trifle matter, so it was in flawless performances that the conductor found his heart swelling with pride and a sense of accomplishment. They sounded wonderful.
On and on the rhythm continued in harmonious unison as the conductor swayed along with the music, nearly losing himself in the beauty he deftly led. ‘lub-DUB, lub-DUB, lub-DUB, lub-DUB-plop, lub-DUB-plop.’ Abruptly woken from his reverie, the conductor lost his composure for a moment and scowled at the left ventricle portion of the orchestra. He had not given permission for them to skip ahead to the Ken-TUCK-y gallop! That was reserved for the 3rd movement. True, the low-pitched ‘plop’ notes were faint, but to the astute ear they rang out like a bell and he should not have to put up such an affront to his leadership!
Closing his eyes and breathing in deeply, the composer regained his composure and firmly took control of the rhythmic tune yet again. Afresh, the melody rang out, fulfilling its vital purpose flawlessly. The ventricular musicians took his silent reprimand to heart and vowed to remain vigilant lest they forget themselves again. Keeping a close eye on the musicians, the prideful conductor began reasoning that it wouldn’t necessarily be a concert ending mistake. The S3 cadence was often tolerable and, with any luck, the audience would consider it part of the performance. Of course, there were always some who kept a wary eye out for mistakes and were quick to accuse them of failure. But with the symphony being so young, it could easily all be explained away. Relaxing his shoulders and loosening his white-knuckled grip on the baton, the conductor slipped back into the music and tried to let the rhythm of the music calm his concerns.
‘Lub-DUB, lub-DUB, lub-DUB,’ went the rhythm and on it continued for many a stanza before the inevitable deterioration began. Once overly compliant and forgetting themselves, the left ventricle section had become more stiff as time wore on. Instead of the melodious synchronization, a faint extra sound began to emerge until the rhythm turned into a galloping, ‘da-lub-DUB, da-lub-DUB, da-lub-DUB.’
Looking up sharply at the sound of the offending notes, the conductor’s face turned a brilliant red. This would not do! Jumping to the third movement could have been explained away, but suddenly progressing all the way to the fourth meant certain ruin. Try as he might, the conductor could not seem to stop the ten-ness-EE movement. As beads of sweat trickled down his face, the rest of the orchestra felt the strain and the atrial section even began to tremble under the stress.
‘Oh no, I can’t lose the atrial ensemble as well!’ the conductor thought as his hands frantically moved to indicate the proper rhythm. But try as he might, the persisted. Faster and faster the atria fibrillated and on persisted the ‘da-lub-DUB’ until finally the conductor threw up his hands in despair. Gathering up what was left of his dignity, the defeated conductor declared, “I now presenting the concertmistress, AV Node, to complete the refrain.”
Medical Morales to Remember:
· Normal Heart Sounds
o S1 – first heart sound, sound of mitral and tricuspid valves closing at the beginning of ventricular contraction (systole)
o S2 – second heart sound, sound of pulmonic and aortic valves closing at the beginning of ventricular relaxation (diastole)
· Gallop Sounds – low frequency sounds typically heard best with bell of stethoscope placed lightly at apex of the heart
o S3 – Ken-tuck-y, low-pitched and occurs during diastole right after S2, caused by rapid ventricular filling (normal finding in children and young adults)
o S4 - Ten-ness-ee, occurs with atrial kick right before S1, caused by ventricle stiffness and decreased compliance
· Sinoatrial Node – pacemaker of the heart, generates and transmits electrical signal for contraction through the atria and to the AV Node
· Atrialventricular Node – slows impulse then initiates ventricular depolarization and contraction