A synchronous, pulsatile angioplasty system utilizes a control apparatus which controls balloon inflation and deflation in a pulsatile fashion synchronized with the heartbeat of a patient. A heart monitor provides an input, a signal to the control apparatus which serves as a baseline for operation of the pulsatile inflation and deflation of the balloon. A triggering circuit reads the baseline signal and generates a control signal to selectively generate valves interconnecting the angioplasty catheter with sources of inflation media and low pressure. Time delay circuits may be utilized which delay either the duration of the control signal or the receipt thereof by the control valves.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates generally to equipment and procedures 
employed in the performance of perfusion catherization procedures, and 
more particularly to a system for operating an angioplasty catheter in a 
pulsatile fashion in synchronization with a heartbeat. 
The use of inflatable balloon catheters in the treatment of coronary 
conditions is widespread. Balloon catheters are commonly used to expand 
blockages in arteries. These blockages are a narrowing of an artery or 
other body vessel, and are referred to as stenoses. In angioplasty 
procedures, a guide catheter is introduced into the artery of the patient 
and guided through the artery until the distal tip of the catheter is at 
the desired location of the coronary artery near the stenosis. A dilation 
catheter having an inflatable balloon affixed to its distal end is 
introduced along the guide catheter and advanced into the patient until 
the balloon end is located at the stenosis. The balloon is subsequently 
inflated to expand it against the artery walls to expand, or dilate, the 
artery and compress the stenosis. This expansion can remove all of or a 
significant portion of the blockage when the balloon is inflated against 
the arterial walls for a preselected time or repeatedly inflated and 
deflated in a cycle to match that of the heartbeat of the patient. 
Once the artery has been expanded, the balloon is deflated and it and the 
guide catheter are removed so that blood may again flow on its own through 
the artery. Restenosis is a condition where the arterial wall has been 
initially expanded by the balloon and the arterial blockage is open but 
the arterial wall contracts and adopts all of or part of its original, 
restricted state sometime after the balloon is deflated and removed. The 
rate of restenosis is believed to be lowered if longer inflation times are 
used during angioplasty balloon catheterization procedures. 
The use of longer balloon inflation times may promote the occurrence of 
ischemia of the cardiac muscles. Ischemia is a local deficiency of oxygen 
in an area of the body caused by an obstruction in the blood vessels 
supplying blood to that area. To prevent ischemia, perfusion catheters are 
used in association with coronary angioplasty catheters. Perfusion 
catheters are catheters which permit the continuous flow of blood through 
the blockage during the inflation of the balloon in the artery. 
An external pump is often used in perfusion angioplasty procedures in order 
to draw blood from the patient by way of an aspiration catheter and 
circulate it back through the perfusion catheter and past the distal end 
of the balloon. External blood pumps have been commonly used for 
regulating blood through coronary arteries during open-heart surgeries. 
These pumps may generally provide either a high or low pressure output. 
External perfusion pumps are well known, such as the one described in U.S. 
Pat. No. 5,066,282 issued Nov. 19, 1991. This patent is directed to a 
perfusion pump with a pulsation-damping mechanism that serves to smooth 
out pressure pulses of the pump during pumping. Other external pumps are 
known which use syringes as their primary components, such as that 
described in U.S. Pat. No. 3,447,479, issued Jun. 2, 1967 which discloses 
an arrangement of syringe pumps which perform alternating suction and 
pumping strokes. In the multiple syringe pump arrangement shown in this 
patent, four syringe pumps are powered by a motor-driven eccentric cam 
drive which utilizes return springs connected to the plungers of the 
syringe pumps in order to ensure a prompt return of the syringe pump 
plungers to their original, ready position within the syringes. The 
pumping cycle of such a mechanism is essentially "fixed" because of the 
curvature of the cam surfaces of the cam. It is not possible to adjust 
such a mechanical type system to mate its pumping action with a heartbeat. 
The present invention is therefore directed to an angioplasty system with a 
control means for selectively controlling the inflation and deflation of 
an angioplasty balloon in synchronization with a patient's heartbeat in 
order to deflate the balloon while the heart is pumping and to inflate the 
balloon while the heart is at rest. The present invention therefore also 
dispenses with the need to utilize a perfusion catheter and its external 
perfusion pump. 
In accordance with one aspect of the present invention, a heart monitor and 
a programmable controller are linked together so that the controller, in 
effect, "reads" the heart rate or pulse of the patient. The controller 
controls a bank, or a manifold, of valves that control the inflation and 
deflation of the angioplasty balloon using a biocompatible inflation 
media, such as helium or carbon dioxide. The valves are operatively 
connected to a pressurized source of inflation media as well as a vacuum 
source to provide for immediate inflation and deflation upon demand in 
response to a signal generated by the controller. 
In another aspect of the present invention, a series of gas pressure 
regulators interconnect the pressurized inflation media source to a series 
of solenoid valves which are operatively connected to a programmable 
control means in order to regulate the pressure of the inflation fluid 
drawn from its source and used for balloon inflation purposes. 
In yet another aspect of the present invention, the programmable controller 
has an adjustable control means with a timing delay means operatively 
associated therewith in order to adjust the frequency of the inflation and 
deflation cycles of the angioplasty balloon so that the balloon may be 
inflated and deflated in synchronization with the patient's heart so that 
angioplasty may be performed with minimal trauma and ischemia occurring. 
The timing delay means permits the programmable controller to synchronize 
the inflation of the balloon (and its deflation) not only to the heartbeat 
of the patient, but also in synchronization with a particular heartbeat, 
such as the fourth or sixth heartbeat, for example, in a chosen cycle. 
Accordingly, it is a general object of the present invention to provide a 
pulsatile, synchronous inflation system for use in angioplasty which 
reduces trauma and ischemia. 
Another object of the present invention is to provide a pulsatile 
angioplasty system wherein the balloon inflation pressure are adjustable 
and may be increased as required. 
Still another object of the present invention is to provide an angioplasty 
inflation/deflation control system having a programmable controller which 
controls and regulates the inflation/deflation of an angioplasty balloon 
in synchronization with the heart rhythm of the patient, thereby 
permitting preselected longer or shorter periods of time of inflation 
during angioplasty and thereby reduces the trauma associated with 
angioplasty. 
Yet another object of the present invention is to provide a synchronous, 
pulsatile angioplasty system having a control apparatus which synchronizes 
the inflation and deflation of an angioplasty balloon with the heartbeat 
of a patient and which controls the inflation and deflation times so that 
the angioplasty balloon may be inflated or deflated at every Nth 
heartbeat. 
These and other objects, features and advantages of the present invention 
will be clearly understood through consideration of the following detailed 
description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a simplified block diagram of a synchronous, pulsatile 
angioplasty system contacted in accordance with the principles of the 
present invention. An angioplasty balloon, generally designated as 10, is 
illustrated in place within a blood vessel 12 of a patient. The 
angioplasty balloon 10 is mounted on an angioplasty catheter 14 at an 
insertion end 16 thereof. The catheter 14 includes an elongated shaft 18 
having one or more internal lumens 20 extending therethrough in order to 
convey an inflation media to the balloon 10 when it is in place within the 
blood vessel 12. 
The distal, or insertion end 16, of the catheter, carries the balloon 10 
thereon in a normally deflated state so that it may be introduced into a 
blood vessel 12 such as a coronary artery in a conventional manner and 
positioned in place at a stenosis or otherwise occluded section of the 
blood vessel 12. The proximal end 24 of the catheter 14 extends out of the 
blood vessel 12 and the patient's body and is equipped with an inflation 
hub 26 which has an opening 28 therein that communicates with the internal 
inflation lumen 20 of the catheter 14. An appropriate connector 30, such 
as a luer connector, is used to connect the catheter inflation hub 26 to 
an inflation-deflation manifold 32, of valves 34 that are specifically 
used to control the inflation and deflation of the angioplasty balloon 10. 
Focusing specifically now on the inflation-deflation manifold 32, it can be 
seen that the manifold bank 32 includes a plurality of inflation control 
valves 34, such as Skinner Model No. MDB005 mini-solenoid valves, in place 
on an equalizer assembly 36. The solenoid operators of those valves 34 are 
interconnected to an inflation-deflation control apparatus 50 by ways 
well-known in the art and in this regard, the valves 34 may be connected 
as at 37 to various circuits of the control apparatus 50. 
Each regulating valve 34 has an inflation media regulator 38 associated 
therewith, preferably a gas pressure regulator, such as a Wilkerson 
R04-01-N00 non-relieving pressure regulator. These inflation media 
regulators are interposed between the regulating valves 34 and a 
pressurized inflation media supply 39 in order to control and vary (if 
desired) the inflation pressure of the media entering the inflatable 
balloon 10. The inflation media supply 39 is shown schematically as a 
pressurized tank 40, which has a charging valve 41 associated therewith 
which controls the flow of inflation-media out of the supply tank 40 and 
into the inflation-deflation manifold 32. The inflation media regulating 
valves 34 and the supply tank charging valve 41 are preferably linked in 
operative communication with the control apparatus 50 by circuitry 37 
extending between the control apparatus 50 and the solenoids on the valves 
34 and 41, and are further preferably all independently adjustable. The 
three pressure regulators 38 independently feed the inflation manifold 
through the three associated solenoid valves 34 which are ganged together 
as depicted on the pressure side "P" of the system. 
A vacuum assembly 40 is also interconnected to the manifold 42 and includes 
a source of low pressure disposed on the vacuum side "V" of the system, 
such as the vacuum pump 44 and a ballast or holding tank 45, illustrated. 
This vacuum line also includes a control valve 46, preferably in the form 
of a solenoid operated valve as described above for the inflation control 
valves 34 of the pressure bank 32. Two such valves 46 may be used in 
conjunction with a vacuum portion of the manifold 32 so that three valves 
34 are dedicated to the pressure made of the system, while two such valves 
46 are dedicated to the vacuum side of the system. 
The solenoids that operate these valves 34, 46 are timed by the controller 
50 and may be operated by a time-delay circuit thereof as explained below. 
The vacuum valves 46 are also preferably operatively connected to the 
control apparatus 50. The inflation media used for inflating the balloon 
10 may be a biocompatible liquid, such as a saline solution, or as used in 
the preferred embodiment of the present invention, it may be a 
biocompatible gas, such as helium or carbon dioxide, both of which are 
inert with respect to body tissues and which are readily absorbed by body 
tissues. 
As will become evident from further reading of this detailed description, 
the ballast tank 45, when a vacuum is maintained on it, importantly 
provides a means for collecting the inflation media from the catheter 14 
during balloon deflation, thereby providing rapid deflation with any range 
of inflation times. This rapid deflation is effected by a signal from the 
controller 50 which is used to control the sequence and timing of 
inflation and deflation of the angioplasty balloon 10. 
Focusing now on FIG. 4, the circuitry 51 of the control apparatus 50 is 
shown schematically. The circuitry 51 is contained within an apparatus 
housing 53 as shown in FIG. 3, and it includes an input circuit 52 which 
receives the pulse from a heart monitoring system, such as an EKG 54 and 
provides a means for monitoring the heartbeat of a patient and a baseline 
pattern for use with the control apparatus 50. The control apparatus 
receives a QRS signal from the EKG monitor 54 applied to the patient. This 
signal is passed through a TTL (transistor-transistor logic) input portion 
of the input circuit 51 and also may also be passed through a filter 
circuit 55 in order to screen undesirable "noise" received in conjunction 
with the input from the EKG monitor 54. 
Means for visually observing the heartbeat, as well as the synchronization 
of the balloon inflation and deflation with the heartbeat may be provided 
in the form of one or more external LEDs ("light-emitting diodes") mounted 
on the panel in positions which are easily visible by the operator. One 
such LED is associated with the heartbeat, or pulse of the patient that is 
received as an input to the control apparatus 50 and is indicated at 56. 
This LED 56 flashes in synchronization with the pulse input of the patient 
so that the operator of the control apparatus can easily visually observe 
it. 
Once the heartbeat or pulse of the patient has been established, that 
baseline signal is sent from the input circuit 52 to a triggering circuit 
58 which provides the operator of the control apparatus 50 with a means of 
selecting a desired synchronization of the operation of the system, i.e., 
a pulsatile inflation and deflation of the angioplasty balloon 10 with the 
heartbeat of the patient or with a particular synchronized heartbeat cycle 
thereof. This cycle may be synchronized to the patient heartbeat input by 
means of a filter circuit 55 in a one-to-one relationship where the 
balloon 10 is inflated and deflated successively with respect to every 
systolic and diastolic beat of the heart. 
More uniquely, it may be synchronized by the filter circuit 55 to a 
particular heartbeat, N, so that the system may inflate the balloon every 
Nth heartbeat while it deflates the balloon 10 and maintains it in a 
deflated state for the intervening heartbeats. For example, when the N 
value is chosen to be 4, the control apparatus 50 will by way of its input 
circuit 52 count the heartbeats received from a patient and every fourth 
heartbeat, the triggering circuit 58 will send a signal to open the 
charging valve 41 and/or the inflation control valves 34 to inflate the 
balloon 10 for a particular predetermined time simultaneously with that 
Nth (fourth) heartbeat, while deflating it upon receipt of a signal from 
the heartrate input circuit 52 indicating the end of the Nth (fourth) 
heartbeat. Similarly, the triggering signal may be sent to initiate an 
inflation of the balloon 10 for a time longer than just a heartbeat, such 
as a 2-second time period to promote an intermittent, but steady inflation 
against the stenoses of the blood vessel 12. 
Returning now to the schematic diagram, FIG. 3, a triggering circuit 58 is 
shown as interconnected to a series of control circuits 60 A-F which may 
be considered as primarily timing circuits in that for the most part, they 
rely upon an elapsed time before actuating their associated control valves 
and/or regulators. One such control circuit 60A operates the charging 
valve 39 in a selective fashion in order to fill, or charge, the inflation 
manifold with inflation media under pressure. The triggering circuit 58 
receives both the input signal from the EKG 54 and also a signal from an 
array of logic gates 59 into which signals are fed from selected control 
circuits 60 A-F, as well as the heartbeat input signal from the input 
circuit 52. The various inputs received in the triggering circuit 
processor 62 are analyzed and a triggering control signal is generated. 
This signal is received by the charging valve, or inflation, circuit 60A 
which controls the operation (i.e., opening and closing) of the charging 
valve 41 of the pressurized supply 40 of inflation media. The triggering 
circuit 58 may be set to trigger an inflation of the balloon with a 
specific heartbeat by way of a rotary selector switch 59. 
Upon opening of the charging valve 41, the output of this charge valve 
control circuit 60A is received by a charge valve closing time delay 
circuit 60B which may be set to delay closing of the charging valve 41 for 
a predetermined time in order to keep it open for the desired inflation 
period. An inflation control circuit 60C receives a control signal as 
output from the charge valve delay circuit 60B and also receives as input, 
the heartbeat signal in order to control operation of the inflation 
control valves 34 when the triggering signal from the triggering circuit 
58 and the heartbeat input signal match. 
An inflation valve closure delay control circuit is provided at 60D in 
order to maintain the inflation control valves 34 in an open position for 
a preselected amount of time as set by a potentiometer 76 as described in 
detail below. One output of this control circuit 60D leads to a vacuum 
triggering circuit 78 which generates a signal from its processor to 
trigger operation of the low pressure control valve 46. The vacuum 
triggering circuit 78 may include a rotary selector switch 80 for 
selecting a predetermined delay in operating the deflation control 
valve(s) 46. This is used in instances where the operator desires to 
deflate the balloon 10 after a desired number of pulses rather than 
immediately after the inflation of the balloon 10. The rotary selector 
switch 80 of this circuit 78 permits the deflation to be delayed in 
predetermined incremental values, such as an Nth heartbeat, up to a 
maximum of 9 heartbeats. 
The control apparatus 50 further includes a control circuit 60E which 
serves to ensure that the inflatable balloon 10 is fully deflated before 
any new event (i.e. another inflation) is processed. One output 82 of this 
circuit 60E is processed through the logic array 59 and is received by the 
triggering circuit processor 62 where it is read and accepted in order not 
to transmit another triggering signal until balloon deflation is 
completed. 
Lastly, the control circuits also include an inflation inhibiting circuit 
60F serves as a balloon overpressure and rupture alarm. This circuit 
receives as input, a signal from a pressure sensor 86 preferably 
positioned in line with the catheter luer connector 30 and triggers an 
alarm circuit 88 which resets the control apparatus cycle and stopping the 
inflation cycle by closing the charging valve 41. 
The triggering circuit 58 is connected to a rotary selector switch 59 
accessible from the front panel of the apparatus 50. This selector switch 
59 selects the desired number of "N" detected heartbeats, or pulses, 
required to trigger an event. Presently, suitable results have been 
obtained using the control apparatus with a maximum limit of 9 heartbeats 
or pulses. An inflation timing control switch 72 extends through the front 
panel of the control apparatus and may be located next to the trigger 
selector switch 59. This control switch 72 preferably takes the form of a 
digital potentiometer 76 with three incremental selectors 73, 74, 75 being 
arranged thereon. This potentiometer has the ability to permit the 
operator to select inflation times of the balloon 10 up to 5 seconds. The 
time is set by choosing the proper incremental valves on the control 
switch 72 ranging from between the baseline setting of 25 milliseconds 
when the switch 59 reads "000" on all these dials thereof and up to the 5 
second maximum. The increments are effected by turning the rightmost 
indicator 75 to obtain a number in the display of between 0 and 9, each 
number representing an integer multiplier of the base value of 5 msec. The 
center indicator 74 results in an increase of 50 msec, while the leftmost 
indicator 73 results in an increase in the inflation time of the balloon 
of 500 msec for each digit. As an example, a setting of "123" on the 
switch 72 yields a total inflation time of 500 msec as shown below: 
EQU Time T=(1.times.500 msec)+(2.times.50 msec)+(3.times.5 msec)+baseline valve 
of 25 msec.=640 msec. 
The control apparatus 50 may be provided with a reset control switch 90 
which will stop all of the functions of the control apparatus by turning 
off all controls to the inflation valves 36 and resetting all of the 
counters of the control apparatus, yet maintaining the vacuum valve(s) 46 
enabled and opened to provide continued deflation. 
The control apparatus 50 also preferably includes inhibit circuits which 
prevent the pressure side P of the system from operating while the vacuum 
side V is operating. A delay is programmed into the inflation valve 
circuits through the inflation delay control circuit 60D in order to 
account for the time it takes for the inflation control valves 34 to 
mechanically close before triggering the vacuum circuit 78. This feature 
is important because if the pressure side P is open at the same time the 
vacuum side V is, the vacuum side will become burdened with the pressure 
and it will take time for the vacuum side to be drawn back down to the 
required vacuum level. The deflation control period circuit 60E which 
controls the vacuum valve(s) 46 inhibits any events from initiating before 
the deflation has run out in order to obtain complete deflation of the 
balloon 10. 
FIG. 5 is a schematic circuit logic diagram that describes the sequence of 
operation of the system of the present invention. As shown in FIG. 5, the 
heart monitor, EKG 54, reads the heartbeat, or pulse, of the patient. The 
pulse input circuit 52 is adjustable to set a predetermined threshold or 
baseline value. Any pulses received from the monitor 54 above this 
threshold or baseline are received by the pulse input circuit 52 and 
identified as a "valid" pulse to the control apparatus. This pulse is then 
passed through the filter circuit 55 which is an adjustable event filter 
that can be selectively adjusted to provide a particular sequence, i.e. it 
passes every pulse, every other pulse, every Nth pulse, etc. 
The selected sequence of the event filter 55 is communicated the trigger 
delay circuit 62 which activates an inflation solenoid valve 34 that is 
connected to a high pressure gas reservoir that serves as the inflation 
media supply 39. The inflation solenoid valve 34 is activated after a 
selected delay time applied to receiving the appropriate signal(s) from 
the circuits 60A, 60B, 60C, and 60D. The vacuum trigger circuit 78 serves 
as a deflation trigger circuit to deflate the balloon 10 by opening the 
deflation solenoid valve 45 either immediately after inflation of the 
balloon 10 or after a selected number N of pulses. 
The deflation refractory circuit 60E overrides any inflation signal from 
activating the inflation valve 34 until the balloon 10 is fully deflated, 
normally 500 to 800 milliseconds, and this circuit 60E further holds the 
deflation solenoid valve 45 open to vacuum until an inflation signal is 
received by the inflation trigger circuit 62. Various "fail-safe" features 
are included as part of the inflation inhibit circuit 60F which serve to 
control the inflation valve 34 and prevent it from operating in the event 
of the balloon 10 or the catheter body 14 bursting or leaking. 
In brief, the present invention takes as input, a heartbeat or pulse 
output, from a suitable heart or blood pressure monitor and correlates the 
inflation and deflation cycles of the controller to the heartbeat input. 
This signal provides the control apparatus with a baseline signal for 
operation so that the balloon may be inflated at particular heartbeats. 
Rather than merely delaying the inflation for a preselected time interval 
after detecting a pulse signal, the present invention correlates the 
pulses to the balloon so that it may be inflated and deflated in 
synchronization with a desired Nth pulse or heartbeat. Once inflated, the 
balloon may be deflated by the operator either immediately after inflation 
or after a preselected number of pulses read by the input. 
While the preferred embodiment of the invention have been shown and 
described, it will be apparent to those skilled in the art that changes 
and modifications may be made therein without departing from the spirit of 
the invention, the scope of which is defined by the appended claims.